Dissertation

Home , Canariella, Chondrula tridens, Discus ruderatus, Granopupa, Harmozica (gastropod), Merdigera

Fakultät Umweltwissenschaften

Investigations on Quaternary environmental changes based on malacological analyses and stable isotope signals

Dissertation

zur Erlangung des akademischen Grades Doctor rerum naturalium (Dr. rer. nat.)

Vorgelegt von: MSc. Christiane Richter Geboren am 13.03.1986 in Dresden

Gutachter: Prof. Dr. habil. Dominik Faust Technische Universität Dresden, Institut für Geographie

Dr. Nicole Limondin-Lozouet Centre National de la Recherche Scientific (CNRS), Paris Laboratoire de Geographie Physique

Prof. Dr. habil. Heinrich Thiemeyer Goethe Universität Frankfurt am Main, Institut für Physische Geographie

Datum der Verteidigung: 04.12.2020

ACKNOWLEDGEMENT

First and foremost, I would like to thank my supervisor Prof. Dominik Faust for his support on my way to a doctorate, for the valuable help whenever needed, the scientific input and constructive criticism, for the trust and room for own ideas but above all for the motivation and encouragement.

Furthermore, I would like to thank Dr. Daniel Wolf for his always open door for questions and problems of all kind, for the precious support with field work(!!), for the constructive criticism and beneficial knowledge in every scientific topic and for the fun when working with him.

I would like to thank Dr. Stefan Meng very much for his help and support, that he was always available to me and for the very pleasant exchange.

I would like to thank Frank Walther for his help and active support, enthusiasm, confidence and valuable knowledge of the gastropod world, which I hope will be retained in future projects.

I thank Dr. Olivier Moine for the good advice and training and Dr. Nicole Limondin-Lozouet for her support and encouragement. Furthermore, I am appreciative to Prof. Michael Zech for his support and to Lucas Bittner, Lisa Zwanzig, Jana Krautz, Dr. Jan Uwe Schmidt and Dr. Christopher Roettig for helpful discussions. I thank Klaus Groh for the pleasant cooperation, help and support with the Canary snail community. Moreover, I sincerely thank Markus Uhlig for the permission and the friendly help regarding the shemozzle in the Geotechnical laboratory of the TU Dresden, where I always felt comfortable and welcome, as well as Luise Hofman and Elisa Marzin for their help. Furthermore, I am appreciative to Dr. Maria Neubauer for the statistical support, Florian Schneider, Philipp Baumgart and Dr. Thomas Kolb for their help with field work, Dr. Stefania Milano for the stable isotope measurements and Dr. Lutz Maul and Prof. Ola Kwiecien for their friendly advice.

I sincerely thank my referees Dr. Nicole Limondin-Lozouet and Prof. Heinrich Thiemeyer for the great kindness to review this doctoral thesis and for their time invested.

I heartly thank the Graduate Academy of the Technical University of Dresden for granting me with a PhD scholarship for young female scientists and enabling me to unify family and PhD.

I thank my parents, without which I would not have gotten this far.

And last, the most important - I thank my husband Uwe for his support, for the process optimisation of the laboratory work and first and foremost for his continuous encouragement, and my children for their constant help with field collections and the positive feedback on my work.

ABSTRACT

Geological sediment archives play a key role in studying the interrelations between ecosystems and environmental changes. The understanding of these interrelations is essential to assess future developments, especially in the light of current climate change. In the study in hand, Quaternary loess-palaeosol sequences of different settings are examined based on biological proxies in the form of gastropods. These (sub)fossil gastropod records allowed us to draw conclusions about environmental and climatic conditions associated with glacial- interglacial cycles of the past up to 400 ka. We compared a highly continental archive in the Southern Caucasus to an oceanic setting on the Canary Islands in order to examine the influence of local peculiarities and to test the applicability of the method in different settings. For this purpose, 180 samples with a total weight of 1800 kg sediment material were processed and wet sieved. They contained gastropod shells of 53.279 individuals and 41 species at least. The investigations comprise three fundamental main compounds:

(I) In the first part we analyse the ecological indication of fossil gastropod assemblages in the sediment archives. The gastropods have proven to be valuable palaeoenvironmental proxies and provide new insights into the environmental history of the study region. Based on our results we assume for the South Caucasian study region, that glacial phases were related to dryer conditions indicated by a predominance of xerophilous shrub steppes, while warmer interglacial and interstadial phases favoured the distribution of mesophilous highgrass- and forest-steppe ecosystems, which indicate moister conditions. Furthermore, we assume that the average July temperatures were never below 10°C even during glacial periods. For the Canary Islands, on the other hand, we found that the ecosystems associated with glacial versus interglacial phases were only secondary influenced by local climate changes. Instead, a strong influx was shown by changes in the substrate, which influence the edaphic moisture properties. These substrate changes were primarily related to volcanism and local sediment availability. In addition, we observed prominent extinction events within the gastropod assemblages on Fuerteventura. In comparison with our stable isotope results and indications by other researchers from marine archives of the Canary Basin, we assume that these extinction events might be related to strong dry-hot winds in the final stages of glacial periods, that were described by Moreno et al. (2001).

(II) We show that it is possible to derive a reliable stratigraphy based on gastropods in the different settings. The Caucasian loess deposits allowed an ecostratigraphic zonation based on displacement and re-immigration of taxa of different ecological groups. In contrast, on the insular setting of the Canary study area, it was even possible to develop a biostratigraphic zonation that includes the extinction of certain taxa on the island. I the latter case, the

II temporary occurrence of particular key species can be used for a first stratigraphic orientation in the field.

(III) In addition, this work includes one of the first studies to investigate stable isotope signals of terrestrial gastropods in geological long-term archives. The Southern Caucasian study region showed, in particular, the difficulty to disentangle the various factors responsible for isotope fractionation, particularly in continental areas. However, the results indicate a strong influence of the prevailing wind systems during different periods. The oceanic position of the Canary Islands, on the other hand, represents a special situation regarding the interpretation of stable isotope signals. We assume, that according stable isotope compositions of certain gastropod taxa allow us to reconstruct mean δ18O signals of the oceanic surface water and to approximate a first correlation of our lithological units with sea level fluctuations. Moreover, we assume, that δ13C shell signals on Fuerteventura enable us to differentiate between substrate- induced (edaphic) and climatic moisture alternations, respectively.

We recommend, that the information that can be derived from stable isotope signals in gastropod shells should not be generalised and that the dominant site-specific factors should always be investigated and taken into account when interpreting the isotope signals.

III

KURZFASSUNG

Geologische Sedimentarchive spielen eine Schlüsselrolle bei der Untersuchung der Wechselwirkungen zwischen Ökosystemen und Umweltveränderungen. Das Verständnis dieser Zusammenhänge ist essentiell, um zukünftige Entwicklungen insbesondere vor dem Hintergrund des aktuellen Klimawandels abschätzen zu können. In der vorliegenden Arbeit werden Quartäre Löss-Paläoboden-Sequenzen verschiedener Untersuchungsgebiete mit biologischen Umweltanzeigern in Form von Gastropodengehäusen untersucht. Diese (sub)fossilen Gastropoden ermöglichen es uns, Rückschlüsse auf Umwelt- und Klimabedingungen zu ziehen, die mit glazial-interglazialen Zyklen der vergangenen bis zu 400 ka in Verbindung stehen. Wir haben ein hochkontinentales Archiv im Südkaukasus mit einem ozeanischen Archiv auf den Kanarischen Inseln verglichen, um den Einfluss lokaler Besonderheiten zu untersuchen und die Anwendbarkeit der Methode in verschiedenen Umgebungen zu testen. Es wurden 180 Proben mit einem Gesamtgewicht von 1800 kg Sedimentmaterial aufbereitet und nassgesiebt. Diese enthielten Gastropodenschalen von 53.279 Individuen und mindestens 41 Arten. Die Untersuchungen umfassen drei grundlegende Hauptbestandteile:

(I) Im ersten Teil analysieren wir die ökologische Indikation fossiler Gastropodengemeinschaften in den Sedimentarchiven. Die Gastropoden haben sich als wertvolle paläoökologische Umweltanzeiger erwiesen und dabei völlig neue Erkenntnisse für die Umweltgeschichte der Untersuchungsregion gebracht. Anhand unserer Ergebnisse gehen wir davon aus, dass die Untersuchungsregion im Südkaukasus während der Glaziale durch xerophile Strauchsteppenvegetation dominiert wurde, welche in feuchteren interglazialen und interstadialen Phasen durch mesophile Feuchtgras- bis Waldsteppenvegetation ersetzt wurde. Des Weiteren gehen wir davon aus, dass die mittleren Juli-Temperaturen selbst während der Glaziale nie unter 10°C lagen. Für die Kanarischen Inseln hingegen gehen wir davon aus, dass die Ökosysteme im Zusammenhang mit glazialen versus interglazialen Phasen nur untergeordnet durch lokale Klimaveränderungen beeinflusst worden. Stattdessen zeigte sich ein starker Einfluss durch Veränderungen im Substrat, welche die edaphischen Feuchtigkeitseigenschaften beeinflussen. Diese Substratveränderungen stehen dabei vermutlich in erster Linie im Zusammenhang mit Vulkanismus und lokalspezifischer Sedimentverfügbarkeit. Zusätzlich beobachteten wir markante Aussterbeevents innerhalb der Gastropodenvorkommen auf Fuerteventura. Im Abgleich mit unseren Isotopenergebnissen und den Indikationen anderer Wissenschaftler aus marinen Archiven des kanarischen Beckens nehmen wir an, dass diese Aussterbeereignisse möglicherweise durch starke trocken-heiße Winde in den Endphasen der Glaziale verursacht worden.

(II) Weiterhin zeigen wir, dass anhand der Gastropodenvorkommen eine zuverlässige Stratigraphie für die unterschiedlichen Untersuchungsgebiete erarbeitet werden kann. Die kaukasischen Gastropodenvorkommen ermöglichen eine ökostratigraphische Zonierung basierend auf Verdrängung und Wiedereinwanderung von Taxa verschiedener ökologischer Gruppen. Im Gegensatz dazu war es aufgrund der Insellage für das kanarische Untersuchungsgebiet sogar möglich, eine biostratigraphische Zonierung zu entwickeln, die das Aussterben bestimmter Taxa auf der Insel einschließt. Bei letzterer kann das zeitlich begrenzte Vorkommen spezifischer Leitarten für eine erste stratigraphische Orientierung im Feld eingesetzt werden.

(III) Darüber hinaus beinhaltet diese Arbeit eine der ersten Studien zur Untersuchung von stabilen Isotopensignalen terrestrischer Gastropoden in geologischen Langzeitarchiven. Die südkaukasische Untersuchungsregion zeigte vor allem die Schwierigkeiten auf, die verschiedenen Faktoren für die Isotopenfraktionierung insbesondere in kontinentalen Gebieten aufzuschlüsseln. Die Ergebnisse deuten auf einen starken Einfluss durch die vorherrschenden Windsysteme während verschiedener Zeiträume hin. Die ozeanische Lage auf den Kanarischen Inseln hingegen stellt eine besondere Situation für die Interpretation der stabilen Isotopenverhältnisse dar. Möglicherweise erlauben uns hier die Isotopensignale ausgewählter Gastropodenarten die mittleren δ18O-Signale der ozeannahen Oberflächengewässer zu rekonstruieren und sich so in einem ersten Schritt einer Korrelation der geologischen Einheiten mit Meeresspiegelschwankungen anzunähern. Darüber hinaus gehen wir davon aus, dass wir für Fuerteventura anhand von δ13C-Signalen der Gastropodengehäuse zwischen substratbedingten (edaphischen) und klimatisch bedingten Feuchtigkeitsänderungen unterscheiden können. Wir empfehlen, die Informationen, die aus den stabilen Isotopensignalen der Gastropoden abgeleitet werden können, nicht zu verallgemeinern und bei der Interpretation stets die ortsspezifisch dominanten Faktoren zu untersuchen und zu berücksichtigen.

TABLE OF CONTENT

ACKNOWLEDGEMENT ...... I ABSTRACT ...... II KURZFASSUNG ...... IV TABLE OF CONTENT ...... VI LIST OF FIGURES ...... IX LIST OF TABLES ...... XI LIST OF ABBREVIATIONS AND SYMBOLS ...... XII 1 INTRODUCTION...... 1

1.1 RELEVANCE AND OBJECTIVE OF STUDYING FOSSIL GASTROPODS IN QUATERNARY DEPOSITS ...... 1 1.2 MAJOR RESEARCH QUESTIONS AND METHODOLOGICAL APPROACH ...... 2 1.3 STUDY SITES...... 3 1.4 REFERENCES ...... 3 2 QUATERNARY GASTROPOD FAUNAS ON THE EASTERN CANARY ISLANDS AND INDICATIONS OF ENVIRONMENTAL CHANGES ...... 7

2.1 INTRODUCTION ...... 8 2.2 GEOGRAPHICAL SETTING ...... 9 2.3 METHODS ...... 11 2.3.1 Fieldwork ...... 11 2.3.2 Laboratory analysis ...... 12 2.3.3 Statistical analyses ...... 12 2.3.4 Generation of malacozones ...... 13 2.4 RESULTS ...... 14 2.4.1 Composition of investigated gastropod assemblages ...... 14 2.4.2 Malacozones ...... 17 2.4.3 Ecological groups based on cluster analysis ...... 21 2.4.4 Taphonomy...... 21 2.5 DISCUSSION ...... 22 2.5.1 Malacological key species as stratigraphic markers ...... 23 2.5.2 Derivation of palaeoconditions from species demands & community palaeoecological indicators 27 2.5.3 Morphogenic aspects derived from taphonomic features ...... 36 2.6 CONCLUSIONS ...... 37 2.7 ACKNOWLEDGEMENT ...... 38 2.8 REFERENCES ...... 38 2.9 SUPPLEMENTARY MATERIAL ...... 47 3 QUATERNARY GASTROPOD FAUNAS IN SOUTHERN CAUCASIA AND INDICATIONS ON ENVIRONMENTAL CHANGES ...... 51

3.1 INTRODUCTION ...... 52 3.2 STUDY AREA ...... 53 3.3 METHODS ...... 54 3.3.1 Fieldwork ...... 54 3.3.2 Laboratory analyses ...... 54 3.3.3 Generation of malacozones ...... 56

3.3.4 Statistical analyses ...... 56 3.4 RESULTS ...... 56 3.4.1 Composition of investigated gastropod assemblages ...... 56 3.4.2 Malacozonation...... 60 3.4.3 Cluster analysis ...... 62 3.4.4 Test of significance ...... 62 3.4.5 Remains of non-mollusc organisms ...... 64 3.5 DISCUSSION ...... 65 3.5.1 Derivation of palaeo ecosystems based on the distribution of modern gastropods ...... 65 3.5.2 What restricted tree growth during glacial phases – drought or cold? ...... 69 3.5.3 Differences between palaeosol-complexes ...... 71 3.5.4 Comparison between sections Sevkar and Bl ...... 72 3.5.5 Reconstruction of palaeoecosystems and humidity conditions ...... 72 3.6 CONCLUSION ...... 76 3.7 ACKNOWLEDGEMENT ...... 77 3.8 REFERENCES ...... 77 3.9 SUPPLEMENTARY MATERIAL ...... 87 4 MALACOLOGICAL INVESTIGATIONS ON EASTERN CANARY SEDIMENT ARCHIVES –STABLE ISOTOPE INTERPRETATION IN AN OZEANIC SETTING ...... 101

4.1 INTRODUCTION ...... 102 4.2 GEOGRAPHICAL SETTING AND STATE OF KNOWLEDGE ...... 103 4.3 METHODS ...... 110 4.4 RESULTS ...... 112 4.5 DISCUSSION ...... 116 4.5.1 Geochemical alteration ...... 116 13 4.5.2 δ Cshell - C3 plants in palaeosurfaces and the role of edaphic humidity ...... 116 4.5.3 Validation of the results with modern shell δ13C signals ...... 118 4.5.4 Influences on δ18O in shells of the genus Theba – a special model for the oceanic setting of Fuerteventura ...... 119 18 4.5.5 δ Oshell and sedimentation patterns – the shift between sea level fluctuations and palaeosurfaces 121 4.5.6 Marine transgressions: Hot winds bring extinction - and subsequent stability induces new communities? ...... 122 ...... 125 4.6 CONCLUSIONS ...... 126 4.7 ACKNOWLEDGEMENT ...... 126 4.8 REFERENCES ...... 127 4.9 SUPPLEMENTARY MATERIAL ...... 133 5 MALACOLOGICAL INVESTIGATIONS AT SOUTH CAUCASIAN SEDIMENT ARCHIVES –STABLE ISOTOPE INTERPRETATION IN A CONTINENTAL SETTING ...... 136

5.1 INTRODUCTION ...... 137 5.2 GEOGRAPHICAL SETTING AND STATE OF KNOWLEDGE ...... 138 5.3 METHODS ...... 143 5.3.1 Fieldwork ...... 143 5.3.2 Laboratory Analyses ...... 143 5.4 RESULTS ...... 144 5.4.1 Gastropod record Achajur ...... 144 5.4.2 Stable isotope results ...... 144

VII

5.5 DISCUSSION ...... 148 5.5.1 Signals in modern snail shells ...... 148 5.5.2 Stable oxygen isotopes in a highly continental setting – the difficulty of the interpretation of δ18O of fossil gastropod shells ...... 150 5.5.3 δ13C signals in Kalitinaia crenimargo – what do nutritional changes tell us? ...... 155 5.6 CONCLUSION ...... 155 5.7 REFERENCES ...... 156 5.8 SUPPLEMENTARY MATERIAL ...... 163 6 SUMMARY AND SYNTHESIS ...... 165

6.1 COMPARATIVE CONSIDERATION OF THE DIFFERENT SETTINGS ...... 165 6.2 MAJOR CONCLUSIONS ...... 169 6.3 PERSPECTIVE ...... 172 6.4 REFERENCES ...... 173

VIII

LIST OF FIGURES

Fig. 2.1 (a) Topographic map of the Canary Islands...... 10 Fig. 2.2 Tributary canyon in the area of Barranco de los Encantados (see Fig. 2.1c) - a succession of various palaeosurfaces has been carved out as terraces due to their higher resistance to erosion ...... 11 Fig. 2.3 Picture plate of the (sub)fossil gastropod species...... 15 Fig. 2.4 Mollusc diagrams for the sections Encantado and Jable, with subdivision into malacozones (see 2.4.2) combined with line plots of Shannon biodiversity index and total abundances for each sample. Sketch and related legend modified from Roettig et al. (2017)...... 16 Fig. 2.5 Mollusc diagram for the section Encantado with subdivision into malacozones (see 4.2) combined with line plots of Shannon biodiversity index and total abundances for each sample. Sketch and related legend modified from Roettig et al. (2017)...... 17 Fig. 2.6 Typically associated gastropod species of the study sites regarding to cluster analysis based on the Morisita similarity index...... 20 Fig. 2.7 Sections Encantado (left) and Melián (right) with line plots of coating rate and breakage ratio. Sketches modified from Roettig et al. (2017)...... 22 Fig. 2.8 Correlation of the sequences Jable, Encantado and Melián based on malacozones (for coloured figures we refer to the web version of the article) ...... 25 Fig. 2.9 Distribution of the four key species Rumina decollata, Pomatias aff. lanzarotensis, Cochlicella n. sp. and Obelus pumilio among the studied sequences (a) and subsequently applied to the standard stratigraphy from Roettig et al., 2017 (b)...... 26 Fig. 2.10 Species richness of modern terrestrial gastropods on Fuerteventura (left) presumably influenced by the relief (right) (Source: left: modified from Alonso & Ibáñez, 2005; right: maps.google.de)...... 27 Fig. 2.11 The map shows the effective climate classification by Köppen-Geiger for the modern distribution area of Obelus pumilio, whereat the species occurs in the small Moroccan patch between Agadir and Essaouira, which corresponds to a cold semiarid climate ..... 31 Fig. 2.12 The most complete sequence Encantado plotted with malacozonation and environmental conditions...... 34 Fig. 3.1 Topographic map of the study region, with the red rectangle marking the study area (modified from maps-for-free.com)...... 53 Fig. 3.2 Mollusc diagram illustrating the species composition and abundances for gastropods of the BL section...... 57 Fig. 3.3 Mollusc diagram illustrating the species composition and abundances for gastropods of the Sevkar section...... 58 Fig. 3.4 Picture plate of the (sub)fossil gastropod species...... 59 Fig. 3.5 Dendrogram showing typically associated gastropod species in the palaeo-record of the studied sections. Assumed ecological categorisations as discussed in Chap. 3.5.1 are marked with brackets...... 62 Fig. 3.6 Diagram showing clay contents and organic carbon contents for all gastropod samples. The ecological implications of the gastropod samples were identified in the sample name labelling and by different signatures as shown in the legend. Different soil colours are distinguished and labelled as shown in the legend. We refer to the digital version for coloured figures...... 63 Fig. 3.7 Categorisation of (orographic) vegetation zones after Akramovski (1976) with modern distributions of the gastropod taxa recorded for sequences Sevkar and BL...... 67 Fig. 3.8 Gastropod results (Mollusc spectrum and malacozonation) and sedimentological parameters (lithofaciestypes, carbonate content and organic carbon content) for

section BL correlated with n-alkane ratios of this study site (Trigui et al., 2019) and palynological record of Litt et al. (2014) for Lake Van...... 68 Fig. 3.9 Proposed changes of treelines related to glacial-interglacial cycles in the study area...... 69 Fig. 4.1 (a) Topographic map of the Canary Islands (Source: modified from stepmap.de), (b) The study area southwest of Lajares with the black arrow indicating the study site (c) The studied outrcrop “Encantado” marked by the black arrow (Source: modified from maps.google.de)...... 104 Fig. 4.2 The section Encantado subdivided into lithological units (according to Roettig et al., 2017 and 2020, modified). All ages are based on infrared stimulated luminescence dating (IRSL), the italic written age was performed on palaeosurface material...... 105 Fig. 4.3 Variables influencing the δ18O signals of land snail shells (according to Siegenthaler (1979) and Schmidt et al. (1999), modified)...... 107 Fig. 4.4 Mollusc diagram for the section Encantado, with subdivision into malacozones and line plots of Shannon biodiversity index and total abundances for each sample (from Richter et al., 2019)...... 110

13 Fig. 4.5 Scatter plot with the δ Cshell signals of fossil shells of the Encantado section and modern snail shells...... 115

18 Fig. 4.6 The boxplot depicts the difference between median δ Oshell for a specific sample position 18 and the average of the median δ Oshell signals for the adjacent sample positions of the surrounding sediment...... 113 Fig. 4.7 Scatter plot with the δ18O signals of the fossil gastropod shells of the Encantado section and modern snail shells (collected at a comparatively moist valley floor close by) and calculated median values, respectively...... 124 Fig. 4.8 The section Encantado plotted with malacozonation and derived environmental conditions according to Richter et al., 2019...... 124 Fig. 4.9 a) Raman spectra of alpine calcite, as well as calcite and aragonite specimens from the RRUFF database, b) Raman spectra of the two modern Theba shells, c) Raman spectra of the four Theba shells of sample E3-8, d) Raman spectra of the four Theba shells of sample E3-1 ...... 124 Fig. 5.1 Topographic map of the study region, with the red rectangle marking the study area (modified from maps-for-free.com)...... 138 Fig. 5.2 Mollusc diagram illustrating the species composition and abundances for gastropods of the BL section...... 142 Fig. 5.3 Mollusc diagram illustrating the species composition and abundances for gastropods of the Achajur section...... 145 Fig. 5.4 Scatter plot and mean values for the δ18O and δ13C signals of the (sub)fossil gastropod shells of the Achajur section...... 146 Fig. 5.5 Scatter plot and mean values for the δ18O and δ13C signals of the (sub)fossil gastropod shells of the BL section. All data refer to the species Kalitinaia crenimargo. The mollusc spectrum (on the left) is based on the ecological information derived from the composition of the gastropod assemblages...... 147 Fig. 5.6 Red arrows show the studied sites for modern gastropod collections of Kalitinaia crenimargo. Coloures refer to average monthly δ18O signals of precipitation for April and are taken from the Waterisotopes database of the University of Utah and are based on models by Bowen & Wilkinson (2002) and refined by Bowen & Revenaugh (2003) and Bowen et al. (2005)...... 150 Fig. 5.7 The figures show the correlation between δ18O in precipitation (A), δ18O of the surface seawater (B) and mean annual temperatures of both surface seawater and air (C) in a global context...... 153

LIST OF TABLES

Tab. 2.1 Gastropod species prevalent in the fossil record and their ecological demands...... 28 Tab. 2.2 Detailed mollusc record for Encantado...... 47 Tab. 2.3 Detailed mollusc record for Melián...... 48 Tab. 2.4 Detailed mollusc record for Jable...... 48 Tab. 2.5 Community ecological and taphonomic indices from gastropod analysis for Encantado...... 49 Tab. 2.6 Community ecological and taphonomic indices from gastropod analysis for Melián...... 49 Tab. 2.7 Community ecological and taphonomic indices from gastropod analysis for Jable...... 50 Tab. 2.8 Record of selective species surveys from fossil deposits in the study area (incomplete) ..... 50 Tab. 3.1 Description of lithofacies types in sections Sevkar and BL...... 55 Tab. 3.2 Vertebrate taxa of the palaeo record represented by micro remains (teeth and bones) sorted by gastropod sample ID`s of the profile site BL...... 64 Tab. 3.3 Supporting information on the luminescence dating procedure...... 87 Tab. 3.4 Regression coefficients and statistics of the correspondence analysis for gastropds and sediment proxies ...... 91 Tab. 3.5 Palaeo-record of the gastropod species for the section BL...... 91 Tab. 3.6 Palaeo-record of the gastropod species for the section Sevkar...... 93 Tab. 3.7 Gastropod taxa included in the palaeo-record and related ecological information...... 94 Tab. 3.8 Checklist of the shelled terrestrial molluscs of Tavush based on a literature survey, own collections and museum material...... 98 Tab. 4.1 Description of the lithological units of section Encantado. Sub units a-e indicate the succession of lithofacies types from the bottom to the top of the referring units...... 106 Tab. 4.2 δ13C signals with mean values and related standard deviation for Encantado (E-1 to E- 27) and modern snail shells (modern) collected at a comparatively moist valley floor close by...... 133 Tab. 4.3 δ18O signals with mean values and related standard deviation and medians for Encantado (E-1 to E-27) and modern snail shells (modern) collected at a comparatively moist valley floor close by ...... 134 Tab. 5.1 Description of the lithofaciestypes of sections BL and Achajur...... 141 Tab. 5.2 Site-specific information and δ18O and δ13C results for the modern gastropod samples. All samples refer to the gastropod species Kalitinaia crenimargo...... 148 Tab. 5.3 Palaeo-record of the gastropod species for the section Achajur...... 163 Tab. 5.4 Palaeo-record of the gastropod species for the section BL...... 164

LIST OF ABBREVIATIONS AND SYMBOLS

App. appendix

CaCO3 calcium carbonate CAM crassulacean acid metabolism (photosynthetic pathway of a plant group with high resistance to aridity) Chap. chapter cf. lat. conifer, similar but not equal to (International Code of Zoological Nomenclature) cm centimetre

CO2 carbon dioxide comp. compare e.g. lat. exempli gratia, for example et al. lat. et alii, and others etc. lat. et cetera, and so on Fig. figure g gram GRIP Greenland ice core HCl hydrochloric acid

HCO3 hydrogen carbonate

H2O water ID identification i.e. lat. id est, that is indet. undetermined ka lat. kilo annos, thousand years kg kilogram km kilometre l litre LSVEC lithium carbonate prepared as reference material for isotope calibration metre m millimetre mm metres above sea level m.a.s.l. north nov. newly discovered species without a name yet NBS name of a reference material made of marble for isotope calibration

XII

O2 oxygen molecule OSL optically stimulated luminescence SEM scanning electron microscope sp. lat. species, the species name cannot or need not to be specified (International Code of Zoological Nomenclature) spp. two or more species of a related genus (International Code of Zoological Nomenclature) ssp. lat. species, following the taxon name it means that the identification subspecies (International Code of Zoological Nomenclature) Tab. table V-PDB Vienna Pee Dee Belemnite (reference material for isotope calibration) W west XRD x ray diffraction 18O oxygen-18 isotope 13C carbon-13 isotope α fractionation index & and � sum of all �� for i = 1 to n ∑ �� =1

% per cent ‰ per mil µm micrometre

XIII

1 INTRODUCTION

1.1 RELEVANCE AND OBJECTIVE OF STUDYING FOSSIL GASTROPODS IN QUATERNARY DEPOSITS

In view of the progressive impact of recent climate change, it is becoming increasingly important to understand and predict the interrelationships between climatic changes and the response of ecosystems. Especially the nature of biosphere and pedosphere is an important indicator for the vitality of ecosystems, their potential to bind pollutants and greenhouse gases and to serve as a resource for humans and other organisms. The effects of changing environmental conditions on ecosystems can at best be investigated by retracing the past. Therefore, one of the most important data sets are geological sediment archives. In this context, Quaternary aeolianite-palaeosol sequences are particularly predestined to investigate terrestrial palaeo-ecosystems and their interplay with climatic conditions (see Pye et al., 1995; Kemp, 2001; Antoine et al., 2001; Zöller & Faust, 2009; Obreht et al., 2019). In general, loess- palaeosol sequences record changes between climatically favourable periods often associated with strongly reduced sedimentation and soil formation, and periods with rather unfavourable climate conditions producing cold steppe or desert-like landscapes (Lieberoth, 1963; Haase et al., 1970; Pecsi & Richter, 1996; Markovic et al., 2008; Antoine et al., 2009; Meszner et al., 2011; Lehmkuhl et al., 2016). These contrasting conditions are generally assumed to be related to glacial-interglacial cycles or stadial-interstadial phases, respectively (see i.a. Kukla et al., 1970). As a great advantage of loess-palaeosol sequences, climatic and environmental changes are recorded by traceable sedimentological or pedogenetic processes. In this context, in addition to stratigraphic evidences, a considerable number of proxies are already known or being developed that offer huge support to reconstruct specific environmental conditions, e.g. based on geochemical methods or sediment facies parameters (e.g. Vandenberghe & Nugteren, 2001; Zech et al., 2009; Obreht et al., 2019; Zeeden et al., 2020). In this dissertation, I want to focus on biological proxies that appear to be most appropriate for assessing certain properties such as the biodiversity or vitality of fossil ecosystems. On the one hand, modifications of biocoenoses indicate climatic or environmental changes, and on the other hand, they directly reflect the feedback of biota to certain environmental influences. In this context, Quaternary gastropods are excellently suited as biological proxy (Ložek,1964 & 1990; Kerney,1977; Mania,1973; Rousseau et al., 1994; Limondin-Lozouet and Preece, 2004; Moine et al., 2005, 2008; Limondin-Lozouet et al., 2017). Due to their robust carbonate shells, they are well preserved in many kinds of sediments and highly sensitive to even minor environmental changes. The present dissertation addresses the methodological enhancement of gastropod analysis as a palaeo-environmental proxy. Beside the application of already

1 established analyses of species compositions, especially stable isotope measurements on fossil gastropod shells were carried out and tested in terms of their suitability to derive palaeoenvironmental information from Quaternary sediment archives.

1.2 MAJOR RESEARCH QUESTIONS AND METHODOLOGICAL APPROACH

The main objectives of this study are: (1) To investigate the effects of environmental conditions on the pedosphere and biosphere in suitable aeolianite-palaeosol archives based on fossil and subfossil gastropod shells (2) To derive information about the environmental history and climate development from long aeolianite-palaeosol records in less studied regions for expanding the scientific knowledge beyond the well-researched regions (3) To attempt a biostratigraphic classification of the chosen sediment archives based on Quaternary gastropod faunas in order to obtain an independent palaeo-ecological classification. (4) To apply stable isotope analyses on gastropod shells to Quaternary archives. As this method is not yet fully developed, it will be examined as to whether stable isotope analyses can provide additional insights into the environmental and climatic history of terrestrial archives. For calibration reasons, stable isotope results will additionally be compared to further independent proxy information and above all with the ecological information derived from the composition of gastropod assemblages.

For answering these questions, we use Quaternary gastropods as environmental and climatic indicators. The application of gastropods as palaeo-environmental proxies is mainly based on two major approaches: First, the compositional analyses of the gastropod assemblages. Hereby species compositions and abundances are examined to achieve a stratigraphic subdivision of geological units and to derive palaeo-environmental conditions (Ložek, 1990; Rousseau & Puisségur, 1990). The second approach is a geochemical approach, which mainly comprises stable isotope analyses on the gastropod shells that can provide information on environmental and climatic conditions. Here we chose to analyse δ18O signals which can serve as indicator for hydrological information (i.a. Yapp, 1979; Magaritz & Heller, 1983; Lécolle, 1985; Zanchetta et al., 2005) and δ13C signals to derive information on the gastropod nutrition (i.a. Goodfriend & Magaritz, 1987; Stott, 2002; Metref et al., 2003). In order to pursue a multi-proxy approach, parameters from both fields are investigated and combined in this study, to be applied to suitable and litho-stratigraphically well processed archives.

1.3 STUDY SITES

In order to approximate a clarification of the above-described objectives, we decided to investigate two independent study areas. As one requirement, the archives should disclose a geological timespan comprising multiple glacial-interglacial cycles. As a second requirement, the archives should provide an adequate fossil gastropod record for the investigated period. Faunal communities are especially sensitive in regions with high endemism that are typically surrounded by geographic barriers. Endemism arises from interruption or impediment of the genetic exchange with populations outside the respective region. A corresponding geographically limited habitat leads to a high degree of specialization and thus sensitivity of the taxa to environmental changes. For such sensitive areas, we investigated the composition of gastropod assemblages across time in a lithostratigraphic context. Therefore, we examined up to 400 ka old aeolianite-palaeosurface sequences on Fuerteventura (described by Roettig et al., 2017) as an isolated oceanic island of the Canary archipelago. Moreover, we processed similarly old aeolianite-palaeosol sequences in the Lesser Caucasus foreland described by Wolf et al. (2016) that belong to an area surrounded by high mountain chains and the Caspian Sea, respectively. Fuerteventura is characterised by a subtropical desert climate with an oceanic influence, while the study area in the Southern Caucasus is today characterised by a humid continental climate of the mid latitudes. We want to compare the morphogenetic and environmental history of both study areas in order to identify local differences and similarities regarding major influencing factors and the methodological approach.

1.4 REFERENCES

Antoine, P., Rousseau, D. D., Zöller, L., Lang, A., Munaut, A. V., Hatté, C. & M. Fontugne (2001). High-resolution record of the last interglacial-glacial cycle in the Nussloch loess- palaeosol sequences, Upper Rhine Area, Germany. Quaternary International, 76, 211-229.

Antoine, P., Rousseau, D.-D., Fuchs, M., Hatté, C., Gauthier, C., Marković, S.B., Jovanović, M., Gaudenyi, T., Moine, O. & J. Rossignol (2009). High-resolution record of the last climatic cycle in the southern Carpathian Basin (Surduk, Vojvodina, Serbia). Quaternary International, 198, 19–36.

Goodfriend, G. A. & M. Magaritz (1987). Carbon and oxygen isotope composition of shell carbonate of desert land snails. Earth and Planetary Science Letters, 86(2), 377-388.

Haase, G., Lieberoth, I., & R. Ruske (1970). Sedimente und Paläoböden im Lößgebiet. In: Richter, H., Haase, G., Lieberoth, I. & R. Ruske (Hrsg.): Periglazial-Löß-Paläolithikum im Jungpleistozän der Deutschen Demokratischen Republik.-Ergänzungsheft, (274), 99-212.

Kemp, R. A. (2001). Pedogenic modification of loess: significance for palaeoclimatic reconstructions. Earth-Science Reviews, 54(1-3), 145-156.

Kerney, M. P. (1977). A Proposed Zonation Scheme for Late-glacial and Postglacial Deposits Using Land Mollusca. Journal of Archaeological Science, Vol. 4, p. 387-390.

Kukla, G. (1970). Correlation between loesses and deep-sea sediments. – Geologiske Foreningen Foerhandlingar, 92: 148–180; Stockholm.

Lieberoth,I. (1963). Lößsedimentation und Bodenbildung während des Pleistozäns in Sachsen. -Geologie,12(2):149–187.

Lécolle, P. (1985). The oxygen isotope composition of landsnail shells as a climatic indicator: applications to hydrogeology and paleoclimatology. Chemical Geology: Isotope Geoscience section, 58(1), 157-181.

Lehmkuhl, F., Zens, J., Krauß, L., Schulte, P. & H. Kels (2016). Loess-paleosol sequences at the northern European loess belt in Germany: distribution, geomorphology and stratigraphy. Quaternary Science Reviews, 153, 11-30.

Limondin‐Lozouet, N. & R. C. Preece (2004). Molluscan successions from the Holo-cene tufa of St Germain‐le‐Vasson, Normandy (France) and their biogeo-graphical significance. Journal of Quaternary Science, 19(1), 55-71.

Limondin-Lozouet, N., Villa, V., Pereira, A., Nomade, S., Bahain, J. J., Stoetzel, E., Aureli, D. & E. Nicoud (2017). Middle Pleistocene molluscan fauna from the Valle Giumentina (Abruzzo, Central Italy): Palaeoenvironmental, biostratigraphical and biogeographical implications. Quaternary Science Reviews, 156, 135-149.

Ložek, V. (1964). Quartärmollusken der Tschechoslowakei. Rozpravy Ústøedního ústavu geologického, Vol. 31, 376 p., Prag.

Ložek, V. (1990). Molluscs in loess, their paleoecological significance and role in geochronology - Principles and methods. Quaternary lnternational, 7(8), 71-79.

Magaritz, M. & J. Heller (1983). Annual cycle of 18 O/16 O and 13 C/12 C isotope ratios in landsnail shells. Chemical geology, 41, 243-255.

Mania, D. (1973). Paläoökologie, Faunenentwicklung und Stratigraphie des Eiszeitalters im mittleren Elbe-Saalegebiet auf Grund von Molluskengesellschaften. Geologie, Beiheft 78/79, p. 1-175, Berlin.

Marković, S. B., Bokhorst, M. P., Vandenberghe, J., McCoy, W. D., Oches, E. A., Hambach,

U., Gaudenyi, T., Jovanovic, M., Zöller, L., Stevens, T. & B. Machalett (2008). Late Pleistocene loess‐palaeosol sequences in the Vojvodina region, north Serbia. Journal of Quaternary Science: Published for the Quaternary Research Association, 23(1), 73-84.

Metref, S., Rousseau, D. D., Bentaleb, I., Labonne, M. & M. Vianey-Liaud (2003). Study of the diet effect on δ 13 C of shell carbonate of the land snail Helix aspersa in experimental conditions. Earth and Planetary Science Letters, 211(3), 381-393. Meszner, S., Fuchs, M. & Faust, D. (2011). Loess-Paleosol-Sequences from the loess area of Saxony (Germany). Quaternary Science Journal, 60(1), 47-65.

Moine, O., Rousseau, D. & P. Antoine (2005). Terrestrial molluscan records of Weichselian Lower to Middle Pleniglacial climatic changes from the Nussloch loess series (Rhine Valley, Germany) - the impact of local factors. Boreas, 34, 363-380.

Moine, O., Rousseau, D. D. & P. Antoine (2008). The impact of Dansgaard-Oeschger cycles on the loessic environment and malacofauna of Nussloch (Germany) during the Upper Weichselian. Quaternary Research, 70(1), 91-104.

Obreht, I., Zeeden, C., Hambach, U., Veres, D., Marković, S. B. & F. Lehmkuhl (2019). A critical reevaluation of palaeoclimate proxy records from loess in the Carpathian Basin. Earth-Science Reviews, 190, 498-520.

Pecsi, M. & G. Richter (1996). Löss: Herkunft - Gliederung - Landschaften. Zeitschrift für Geomorphologie, Supplementband 98, Berlin.

Pye, K. (1995). The nature, origin and accumulation of loess. In: Quaternary Science Reviews 14.7/8, pp. 653-667.

Roettig, C. B., Kolb, T., Wolf, D., Baumgart, P., Richter, C., Schleicher, A., Zöller, L. & D. Faust (2017). Complexity of quaternary aeolian dynamics (Canary Islands). Palaeogeography, Palaeoclimatology, Palaeoecology, 472, 146-162.

Rousseau, D. D. & J. J. Puisségur (1990). A 350,000‐year climatic record from the loess sequence of Achenheim, Alsace, France. Boreas, 19(3), 203-216.

Rousseau, D. D., Limondin, N., Magnin, F. & J. J. Puisségur (1994). Temperature oscillations over the last 10,000 years in western Europe estimated from terrestrial mollusc assemblages. Boreas, 23(1), 66-73.

Stott, L. D. (2002). The influence of diet on the δ13C of shell carbon in the pulmonate snail Helix aspersa. Earth and Planetary Science Letters, 195(3-4), 249-259.

Vandenberghe, J. & G. Nugteren (2001). Rapid climatic changes recorded in loess

5 successions. Global and Planetary Change, 28(1-4), 1-9.

Wolf, D., Baumgart, P., Meszner, S., Fülling, A., Haubold, F., Sahakyan, L., Meliksetian, K. & D. Faust (2016). Loess in Armenia - stratigraphic findings and palaeoenvironmental indications. Proceedings of the Geologists' Association, 127(1), 29-39.

Yapp, C. J. (1979). Oxygen and carbon isotope measurements of land snail shell carbonate. Geochimica et Cosmochimica Acta, 43(4), 629-635

Zanchetta, G., Leone, G., Fallick, A. E. & F. P. Bonadonna (2005). Oxygen isotope composition of living land snail shells: Data from Italy. Palaeogeography, Paleoclimatology, Palaeoecology, 223(1), 20-33.

Zech, M., Buggle, B., Leiber, K., Marković, S.B., Glaser, B., Hambach, U., Huwe, B., Stevens, T., Sümegi, P., Wiesenberg, G. & L. Zöller (2009). Reconstructing quaternary vegetation history in the Carpathian Basin, SE Europe, using n-alkane biomarkers as molecular fossils: problems and possible solutions, potential and limitations. Quaternary Science Journal,58, 148–155.

Zeeden, C., Obreht, I., Veres, D., Kaboth-Bahr, S., Hošek, J., Marković, S. B., Bösken, J., Lehmkuhl, F., Rolf, C. & U. Hambach (2020). Smoothed millennial-scale palaeoclimatic reference data as unconventional comparison targets: Application to European loess records. Scientific reports, 10(1), 1-13.

Zöller, L. & D. Faust (2009). Lower latitudes loess - Dust transport past and present. Quaternary International, 196, 1-2.

2 QUATERNARY GASTROPOD FAUNAS ON THE EASTERN CANARY ISLANDS AND INDICATIONS OF ENVIRONMENTAL CHANGES

Chapter 2 is published in the peer-reviewed journal Quaternary Science Reviews as:

CHANGES IN PLEISTOCENE GASTROPOD FAUNAS ON FUERTEVENTURA (CANARY ISLANDS) AND IMPLICATIONS OF SHIFTING PALAEOENVIRONMENTAL CONDITIONS

Authors: Christiane Richter1, Christopher-Bastian Roettig1, Daniel Wolf1, Klaus Groh², Thomas Kolb³, Dominik Faust1

1Dresden University of Technology, Helmholtzstraße 10, 01069 Dresden 2Hinterbergstr. 15, D-67098 Bad Dürkheim 3University Bayreuth, Universitätsstraße 30, 95440 Bayreuth

Publication history: submitted: November 2018, accepted: February 2019

Full reference: Richter, C., Roettig, C. B., Wolf, D., Groh, K., Kolb, T. & D. Faust (2019). Changes in Pleistocene gastropod faunas on Fuerteventura (Canary Islands) and implications on shifting palaeoenvironmental conditions. Quaternary Science Reviews, 209, 63-81.

Abstract. Malacological studies on Middle to Late Pleistocene aeolianite-palaeosurface sequences have been approached in order to detect environmental changes and system shifts on the eastern Canary Islands. Our results reveal that over the last approximately 360 ka, gastropod associations changed fundamentally, allowing the derivation of eight different biozones. The majority of these malacozones and particular species were limited to specific stratigraphic positions and periods. We therefore assume that Quaternary gastropods on Fuerteventura may offer the opportunity to correlate lithostratigraphic units on the basis of key species. Furthermore, environmental conditions could be derived from these associations pointing to colder semi-arid conditions related to the Obelus Zone around 360 to 340 ±30 ka, a subsequent temperature rise around 340 ±30 ka leading to moderate and dryer conditions for the Cochlicella Zone, a strong environmental change around 300 ±30 ka with frequent ephemeral rainfalls for the Pomatias Zone and an increase in temperature and aridity for Late Pleistocene deposits linked to the Rumina Zone. We assume that shifts in malacozonation were triggered by changing climate conditions. Furthermore, the alternation between sand layers and palaeosurfaces is not continuously in conformity with malacozonation. We therefore assume these stratigraphic changes to be not primarily related to climatic forcing, but instead biased by an overlap of multiple factors. As palaeosurfaces indicate favourable conditions

(increased gastropod biodiversity and distinct shrub vegetation), we assume that these were caused by increased edaphic moisture due to a better water holding capacity in silty palaeosurfaces, rather than by more humid climate conditions.

2.1 INTRODUCTION

During the Quaternary, there has been a continuous changeover between glacial and interglacial periods, as well as stadial and interstadial subperiods. These climatic changes were accompanied by major sea-level fluctuations that exerted particular effects on the palaeoecological and geodynamical situation of coastlines and smaller islands. In this context carbonate aeolianites with intercalated silty reddish palaeosurfaces on the eastern Canary Islands seem to be especially suitable to investigate the impact of Pleistocene environmental changes on island ecosystems. On Fuerteventura, up to 20 m thick unconsolidated aeolianite sequences with intercalated palaeosurfaces are well exposed due to deeply incised modern gully systems. On the eastern Canary Islands, such sequences have been studied first by Meco & Pomel (1985). Further studies have been carried out inter alia by Petit-Maire et al. (1986 & 1987), Rognon et al. (1989), Damnati et al. (1996), Meco et al. (1997), Bouab & Lamothe (1997), Coello et al. (1999) and, more recently, by Ortiz et al. (2006), Meco et al. (2008), Suchodoletz et al. (2010), Criado et al. (2011), Faust et al. (2015) and Roettig et al. (2017 and 2018). It was assumed for a long time that the formation of palaeosols on the Canary Islands would reflect long-lasting geomorphologically stable phases during glacial periods that include a standstill in sand supply and long-lasting periods of surface exposure (Damnati et al. 1996; Faust et al., 2015). Furthermore, palaeosols are considered to reflect more humid climatic conditions (Suchodoletz et al., 2009 & 2010, Criado et al., 2011). However, more recent studies suggest that silty reddish layers separating the sand units have been formed regardless of varying climate conditions (Faust et al. 2015). According to Roettig et al. (2017; 2018), the presumed palaeosols should more appropriately be interpreted as palaeosurfaces that experienced a strong enrichment with silt-sized Saharan dust material contributing to the reddening during times of reduced sand supply. This is supported by the fact that these silty reddish layers show only indistinct pedogenic features which are limited to de- and recalcification and oxidation processes (Roettig et al., 2018). Further investigation of environmental circumstances that may have affected palaeosol development (in the sense of palaeosurfaces) is important. For this purpose, it is essential to extract climatic evidence from these aeolianite-palaeosurface sequences. The deposits show a frequent occurrence of fossil gastropods, which may provide significant insights into palaeoenvironmental conditions. Fossil gastropods feature a stable carbonate shell, promoting their preservation in a variety of terrestrial sediments. Moreover, gastropods are highly indicative of ecological conditions and

8 very sensitive to even minor environmental changes. Accordingly, they were widely used as environmental proxy in Quaternary research over the last decades (Ložek, 1964; Kerney, 1977; Mania, 1973; Ložek, 1982; Rousseau et al., 1990; Limondin-Lozouet and Preece, 2004; Moine et al., 2005, 2008; Limondin-Lozouet et al., 2017).

For the eastern Canary Islands, investigations on mollusc faunas in Quaternary deposits have been conducted inter alia by Groh (1985), Hutterer (1990), Fischer (2003a), and, more recently, by Yanes et al. (e.g. 2004 and 2011). Moreover, Bank et al. (2002), Alonso & Ibáñez (2005), Castillo et al. (2007), and Serna & Gomez (2008) listed fossil and modern land snail records partially in combination with detailed distribution areas for Fuerteventura and the Canary Islands respectively (see Alonso & Ibáñez, 2005). These studies give valuable information on the unique malacofauna of the eastern Canary archipelago, which is characterised by high endemism due to the islands´ isolated location.

However, species distributions strongly correspond to the presence of microhabitats. Therefore, the spatial variability of habitat characteristics within the same study area might be equally strong as their temporal variability at one particular site. Accordingly, the study at hand considers the changes in mollusc associations over time at several fixed locations. These malacological studies are based on the lithostratigraphic record published by Roettig et al. (2017) and supply information for a period of about 360 ka. The aim of this research is to investigate the malacofauna with regard to the development and transformation of gastropod associations over time, and resulting information on changes in climatic conditions. We intend to work out a biozonation of the aeolianite deposits and discuss the accordance with lithostratigraphic findings by Roettig et al. (2017). Our results provide substantial information on palaeoenvironmental conditions that were related to the formation of aeolianite-sequences in the study area. They furthermore give new insights into the Mid to Late Pleistocene biogeographic history of northern Fuerteventura.

2.2 GEOGRAPHICAL SETTING

Fuerteventura belongs to the easternmost islands of the Canary archipelago. The study area is located at the northern part of the island, southwest of Lajares (Fig. 2.1). This area is especially suitable for geological and geomorphological investigations as Quaternary unconsolidated deposits are deeply incised by numerous barrancos (radial gullies along volcano slopes) and wadis (dry-valleys), enabling a far-reaching lateral tracing of lithological layers and units (Fig. 2.2). Dune sands on Fuerteventura are primarily composed of carbonates (up to 85% after Roettig et al., 2017), which mainly consist of shallow marine bioclastic components. These sands were deflated from shelf areas during marine regressions, and

9 subsequently formed inland dunes and other aeolian deposits (Rothe, 2008). Those deposits partially underwent repeated erosion and reworking. The aeolianite sequences in the study area can additionally contain volcanic fallout deposits (lapilli and tephra) or coarse components from reworked basaltic solid rocks or caliches. Furthermore, the eastern Canary Islands are influenced by the north easterly trade winds interrupted by Calima events reaching the island from eastern direction. Prevailingly the latter one provides vast amounts of Saharan dust (Criado & Dorta, 2003; Suchodoletz et al., 2009; Criado et al., 2011; Muhs, 2013). Thus, silt- sized dust is an important component that has been admixed in varying quantities into the succession of sand layers. In the more recent past, intense linear erosion processes led to the formation of deeply incised and widely branched gully-systems pervading the whole study area (Fig. 2.2).

Fig. 2.1 (a) Topographic map of the Canary Islands (Source: modified from stepmap.de), (b) Northern Fuerteventura - the study area is marked by the black rectangle (Source: modified from maps-for- free.com), (c) The study area southwest of Lajares that is indicated in (b) showing the wadi Barranco del Jable left hand of the Melián pit and its three main tributary wadis. Arrows indicate the position of the three investigated profiles. Illustrated rivers are episodic and water runs only in case of heavy rainfall events (Source: modified from maps.google.de).

The modern climate of Fuerteventura is, according to the Köppen-Geiger climate classification, allocated to the subtropical desert zone (see Peel et al., 2007). Rivers are episodic and annual precipitation is below 200 mm. The Canary Islands are mainly influenced by north-east trade winds bringing humidity through orographic rainfall. Due to relatively low altitudes of the eastern Canary Islands (809 m a.s.l. maximum on Fuerteventura), these rainfalls generally pass by (Juan et al., 2000). Occasionally, western cyclones bring rainfalls during winter (Faust, 2015).

Fig. 2.2 Tributary canyon in the area of Barranco de los Encantados (see Fig. 2.1c) - a succession of various palaeosurfaces has been carved out as terraces due to their higher resistance to erosion

2.3 METHODS

2.3.1 Fieldwork

Based on detailed lithostratigraphic and geochemical investigations in different dune areas on northern Fuerteventura by Roettig et al. (2017), three aeolianite sequences were sampled for mollusc analyses. These sequences (sections Melián, Encantado, and Jable) are located south of Lajares as shown in Fig. 2.1. The location Jable corresponds to Jable 1 in Roettig et al. (2017). Samples were taken analogous to lithological units as shown in Figs. 2.4 & 2.5 with a volume of 10 litres each. At the section Encantado, 26 samples were taken over a thickness of 15 meters, and at the section Melián, 27 samples were taken over a thickness of 10 meters. Whereat sample 22 of Encantado and sample 15 of Melián could not be processed for mollusc analysis due to their strongly cemented texture. Additionally, we took two reference samples at the section Jable (Fig. 2.1), which correspond to the two palaeosurfaces with the strongest palaeosol-features for comparison and correlation with the other sequences.

2.3.2 Laboratory analysis

All samples were wet sieved to the fraction > 1 mm1 to extract the shells. Samples with very high mollusc abundances were split and reduced to half, quarter or sometimes eighth of the original volume. For this purpose, a standard partitioning procedure was applied to keep a representative sample. Quantities determined from split samples were extrapolated to the original volume in order to keep the comparability between assemblages. Consequently, there is an increased risk for these samples that rare species are underrepresented or missed out. The number of splitting can be extracted from the mollusc records (Tabs. 2.2 to 2.4). Qualitative and quantitative analyses were performed using a MÜLLER MTX-4c stereo microscope. For quantitative compilation of data, complete shells and unique fragments (apices, umbilici and apertures) were extracted and the number of individuals was quantified. Therefore, fragments were set off against each other. Individuals of the genus Theba have not been identified to species level due to their bad preservation. Frequent coatings and strong breakage (mean breakage rate of 60 to 72%) of Theba shells impede a dependable determination on species level as the variation in the genus Theba is immense (see Greve et al., 2010) and complete adult shells are required for reliable determinations.

2.3.3 Statistical analyses

Breakage ratio

For evaluating the quality of taphonomic preservation, a breakage ratio has been established. Therefore, the number of broken and complete shells was determined for all individuals of the genus Theba, as Theba is omnipresent among the samples and to compare equally fragile shell types. The breakage ratio was calculated for each assemblage by dividing the number of broken individuals (not to be confused with fragments, as multiple fragments can belong to the same individual) by the total number of individuals. The resulting ratio thus varies from 0 (no shells broken) to 1 (all shells broken).

Coating ratio

In the purpose of indexing post-depositional processes, a coating ratio has been established. Therefore, only complete shells of the genus Theba were considered. Shell fragments were

1 It is important to remark that sieving of the samples to >1 mm turned out to be not adequate as the smallest species known from the Eastern Canary Islands, Truncatellina purpuraria, is smaller than 1 mm. Thus, this species was not accounted in this study. As Wenzel (2017) investigated fossil molluscs from a shell bed south of Corralejo (northern Fuerteventura) which included Truncatellina purpuraria, it is probable that this species occurs among the studied samples. Consequently, future investigations require an adjustment of the sieve method to 500 µm mesh width.

12 omitted for the calculation, as broken shells in most cases lead to a breakage and loss of preceded coatings and thus do not provide substantive data. The coating ratio was calculated for each assemblage by dividing the number of coated shells by the total number of shells. It ranges from 0 (no shells coated) to 1 (all shells coated).

Biodiversity-Index

For quantifying biodiversity, the index by Shannon (1948) was used. This index is upwardly open and rises with increasing species richness as well as increasing equitability. Equitability describes whether all species prevail in the same commonness and whether a biotope is stable and conditions are well-balanced or rather unstable and dominated by certain stress factors (see Magurran, 1988). The Shannon biodiversity index was calculated as demonstrated in Shannon (1948).

Cluster analysis

The cluster or similarity analysis is a statistical method for determining the similarity between assemblages. Cluster analysis in this study was based on the Morisita similarity index (Morisita, 1959), which compares qualitative presence-absence data as well as quantitative abundance data. Thus, it allows merging phases of species. The index was calculated for all pairs of samples using the palaeontological statistics software PAST. The results are shown in a dendrogram, where most similar samples are aggregated to clusters. The Morisita similarity index varies from 0 (no similarity) to 1 (complete similarity) and was calculated according to Morisita (1959).

Correlation coefficient (r)

The PEARSON correlation coefficient was used for quantification of the relation between species-dependent abundances and gastropod biodiversity. It was calculated for the section Encantado, as this is the site which was least influenced by reworking processes. The correlation coefficient varies from -1 (negative correlation), 0 (no correlation) to 1 (positive correlation) and was calculated according to Pearson (1909).

2.3.4 Generation of malacozones

Subdivision of the sections into malacozones was based on consideration of various characteristics. These include first and last occurrences as well as abundance zones (peak phases) of particular species, and severe changes in biodiversity. The species Theba spp. indet. and Monilearia monilifera occur in all samples in very high abundances, and thus outnumber all other species. For still being able to compare the samples, both species have

13 been omitted for the categorisation of malacozones, unless they were the only species with representative abundances in an assemblage.

2.4 RESULTS

2.4.1 Composition of investigated gastropod assemblages

The gastropod fauna encompasses minimal 16 terrestrial species (see Fig. 2.3). The species complex Theba spp. indet. includes Theba arinagae and Theba geminata as well as presumably two new species of the genus which were registered in selective species surveys at the outcrop locations (see. Fig. 2.3, Tab. 2.8; comp. Hutterer (1990)). Likewise, shells of Hemicycla spp. indet. correspond to a complex of species, which could not be safely allocated because of the poor shell preservation. Hemicycla spp. indet. includes Hemicycla sarcostoma, Hemicycla aff. sarcostoma (Fig. 2.3), Hemicycla cf. paeteliana and possibly Hemicycla gravida, which was registered in selective species surveys in the study area (Fig. 2.3, Tab. 2.8). A detailed record of the contained gastropod shells as well as the Shannon biodiversity index and total abundances are illustrated in mollusc diagrams Figs. 2.4 & 2.5, whereat more detailed data can be found in the Supplementary material charts A.1-A.3. The species composition throughout the sequences shows fundamental changes, allowing the definition of eight different malacozones. Community-ecological parameters show a maximum biodiversity in samples 8, 12, and 26 of section Encantado, and samples 6, 8-11, and 28 of section Melián. As a general trend, biodiversity maxima appear within layers that represent palaeosurfaces. These palaeosurfaces are characterised by strongest enrichment of silty, reddish dust material, because they have been exposed for a longer time span.

Fig. 2.3 Picture plate of the (sub)fossil gastropod species. 1) Hemicycla sarcostoma (a-apical view, b- umbilical view, c-apertural view), 2) Hemicycla aff. sarcostoma, 3) Hemicycla cf. paeteliana, 4) Hemicycla n. sp., 5) Canariella plutonia, 6) Petrified Anthophora chamber, 7) Candidula ultima n. ssp., 8) Theba arinagae, 9) Theba geminata, 10) Theba sp 1 (comp. Tab. 2.8)., 11) Pomatias aff. lanzarotensis, 12) Cryptella auriculata, 13) & 14) Cochlicella n. sp., 15) Rumina decollata 16) Rumina decollata (juv.), 17) Rumina saharica, 18) Xerotricha lancerottensis, 19) Monilearia monilifera, 20)

Caracolina lenticula, 21) Egg of Rumina, 22) Obelus pumilio, 23) Obelus cf. discogranulatus, 24) Ferussacia valida, 25) Ferussacia fritschi, 26) Ferussacia n. sp., 27) Ferussacia submajor, 28) Granopupa granum

Fig. 2.4 Mollusc diagrams for the sections Encantado and Jable, with subdivision into malacozones (see 2.4.2) combined with line plots of Shannon biodiversity index and total abundances for each sample. Sketch and related legend modified from Roettig et al. (2017).

Fig. 2.5 Mollusc diagram for the section Encantado with subdivision into malacozones (see 4.2) combined with line plots of Shannon biodiversity index and total abundances for each sample. Sketch and related legend modified from Roettig et al. (2017).

2.4.2 Malacozones

By comparing the gastropod assemblages of all samples within the same locality, it is possible to detect differing species associations. Therefore, not only the presence or absence of species is considered, but also total abundances, biodiversity and peak phases of certain taxa. This is particularly important as these parameters allow additional predications about palaeoenvironmental conditions and habitats. In this context, eight different malacozones and one subzone were defined. These malacozones correspond to ecozones, as they partially recur (comp. Theba zone) and are defined by the presence of predominantly subfossil species.

They are composed as follows1.

MZ A - Cryptella Zone

Encantado 9-8.7 m (samples 1 to 2); Melian 11.3-10.2 m (samples 1 to 3)

This malacozone is characterised by a predominance of Cryptella auriculata and occasional appearance of Xerotricha lancerottensis. Biodiversity and species abundances are comparatively poor.

MZ B - Obelus Zone

Encantado 8.7-7.6 m (samples 3 to 6); Melian 10.2-10 m (sample 4)

Biozone B shows an increase in species richness and is characterised by abundant incidence of Obelus pumilio. Obelus pumilio shows its main peak phase and occurs simultaneous with Cochlicella n. sp. and Cryptella auriculata.

MZ C - Cochlicella Zone

Encantado 7.6-6.2 m (samples 6 to 10); Melian 10-7.7 m (samples 5 to 10)

This zone is characterised by the predominance of Cochlicella n. sp. with simultaneous occurrence of Cryptella auriculata. These species are often associated with species of the genus Hemicycla. Biodiversity strongly increases compared to the previous zones, reaching absolute maxima in both sections. Sporadically occurring species in this zone are Caracollina lenticula, Canariella plutonia, Candidula ultima n. ssp., Ferussacia valida, Granopupa granum, Obelus pumilio, Pomatias aff. lanzarotensis and Xerotricha lancerottensis.

MZ D - Theba-Monilearia Zone

Encantado 6.2-5.8 m (sample 11), 5.4-4.8 m (sample 13), 4.2-3.5 m (samples 17 to 18), 2-1 m (sample 25); Melian 7-6.7 m (sample 13)

A poor fauna of only Theba spp. indet. and Monilearia monilifera represents this malacozone. These two taxa are occasionally accompanied by an additional low-abundant species. This association is assumed to reflect very stressed ecosystems with extreme dryness. Possibly, they furthermore tolerated sudden strong inputs of dust or tephric material.

1 all malacozones are dominated by Theba spp. indet. and Monilearia monilifera unless differently mentioned

MZ E(a) – Lower Pomatias Zone

Encantado 5.8-5.4 m (sample 12); Melian 7.6-7.4 m (sample 11); Jable 5.7-5.4 m (sample 2)

This malacozone shows a fundamental change to the previous fauna of zone C. Biodiversity decreases weakly but the species composition shows fundamental changes. Pomatias aff. lanzarotensis has its main peak phase and occurs simultaneous with Canariella plutonia and occasionally Hemicycla n. sp. and Cryptella auriculata. This zone is characterised by a strong abundance decline for Cochlicella n. sp. and Monilearia monilifera. Sporadically occurring species in this zone are Ferussacia valida and Caracollina lenticula.

MZ E(b) - Upper Pomatias Zone

Encantado 3.5-2.3 m (samples 19 to 23); Melian 7.3-7 m (sample 12); Jable 4.2-3.8 m (sample 1)

At section Encantado, this zone is separated from MZ E(a) by malacozones D and F. These poor faunas (MZ D/F) indicate a period with extreme environmental conditions. MZ E(b) shows similarities with MZ E(a) but yields moderate to good conditions for Monilearia monilifera again. Simultaneously Candidula ultima n. ssp. occurs, which is not included in MZ E(a). There is a strong decline in abundance of Pomatias aff. lanzarotensis. Nevertheless, climatic conditions in zone MZ E(a) are supposed to be related to those of MZ E(b), as both zones supply enhanced conditions for Pomatias aff. lanzarotensis.

MZ F - Theba Zone

Encantado 4.8-4.2 m (samples 14 to 16); Melian 4.4-4.2 m (sample 22)

This zone is equal to MZ D, but without the occurrence of Monilearia monilifera. The species poverty points to even more hostile conditions than in MZ D. This high stress was presumably related to extreme events like intense accumulation of volcanic fallout or sand deposits.

MZ G – Rumina-Caracollina Zone

Melian 7-6.3 m (sample 14)

This zone is only present at section Melián and characterised by a distinctive increase in species richness and equitability. The related fauna shows a predominance of Rumina

19 decollata, Caracollina lenticula and Hemicycla spp. indet. Sporadically occurring species in this zone are Xerotricha lancerottensis, Granopupa granum and Ferussacia valida.

MZ H - Rumina Zone

Encantado 2.3-2 m (sample 24), 1-0 m (samples 26 to 27); Melian 6.4-4.4 m (samples 15 to 21), 4.2-2 m (samples 23 to 28)

This zone is characterised by low species richness and encompasses the top layers of the sections Encantado and Melián. It differs from the previous zones by a strong decline in biodiversity (compared to MZ G) and a fundamental change in species composition (compared to MZ Eb). Predominant species is Rumina decollata mostly associated with Xerotricha lancerottensis. Sporadically occurring species in this zone are Hemicycla cf. paeteliana, Granopupa granum, Caracollina lenticula and Candidula ultima n. ssp.

Figures 2.4 & 2.5 illustrate the studied sequences subdivided into malacozones.

Fig. 2.6 Typically associated gastropod species of the study sites regarding to cluster analysis based on the Morisita similarity index.

2.4.3 Ecological groups based on cluster analysis

In the following, we aggregated typically associated species with similar peak phases in order to identify species with similar ecological demands. Therefore, we considered the presence or absence of particular species and incorporated the related abundances. Hence, we applied a cluster analysis based on the Morisita similarity index (see Chap. 2.3.3). For this analysis, all data of the samples referring the sections Melián, Encantado, and Jable were assembled in order to create one data pool. Therefore, species occurrences limited to two or less samples (Obelus cf. discogranulatus, Rumina saharica) were not considered, to ensure representative clusters. The results are illustrated in the dendrogram in Fig. 2.6. Related ecological implications of each clustered group are derived from the ecological demands of respective included species and are discussed in Chap. 2.5.2.

2.4.4 Taphonomy

Taphonomic preservation is reflected by breakage ratio and coating rate. Results are shown in Fig. 2.7 whereat detailed data can be found in the Supplementary material Tables 2.5 - 2.7. The breakage rate is highest in Encantado samples 9, 11, 16 and 23 to 24, and in Melián samples 12, 17, 25 and 27. These samples primarily correspond to sediments from the base of lithological units predominantly consisting of coarse sand. Melián samples 6, 25 and 27 also show high shell breakage rates but refer to a loamy substrate. Minimal breakage ratios were observed in section Melián for the samples 3, 7, 9, 10 and 13, and in section Encantado for the samples 5, 12, 18 to 20 and 25 that predominantly refer to layers with palaeosurface facies. The breakage ratio in section Melián is always above 0.4 and on average 0.72, whereas section Encantado shows lower breakage rates starting at 0.2 with an average value of 0.61. The coating rate is lowest in Encantado samples 1, 9, 16, 20, 24 and 26, and shows maxima in samples 2 to 3, 7, 12, 15, 17, 21, 25 and 27. At section Melián, minimal values appear for samples 12, 14 to 16, 18 and 20 to 27. Maxima comprise samples 3-6, 9-10, 13, 17, 19 and 28. The results point to an increased degree of coating in palaeosurface facies and minimal coating rates for unmodified sandy layers. Coating and breakage rate tend to be inversely correlated to each other.

Fig. 2.7 Sections Encantado (left) and Melián (right) with line plots of coating rate and breakage ratio. Sketches modified from Roettig et al. (2017).

2.5 DISCUSSION

The interpretation of malacological results is based on the stratigraphic distribution of particular gastropod communities (Chap. 2.5.1), palaeoecological evidences (Chap. 2.5.2), as well as taphonomic implications (Chap. 2.5.3). Furthermore, the detailed lithological descriptions of

22 the sequences are considered. A short stratigraphic overview of the investigated profiles is given in Figs. 2.4 and 2.5, while descriptions that are more detailed can be found in Roettig et al. (2017). Related chronological ages are based on infrared-stimulated luminescence dating on feldspar (see Roettig et al., 2017).

2.5.1 Malacological key species as stratigraphic markers

Biozones are supposed to represent an ecostratigraphic subdivision of sedimentary sequences and imply changes in environmental conditions. The identified malacozones of this study include associations that recurred repeatedly. These encompass the malacozones that are nearly reduced to Theba spp. indet. and Monilearia monilifera, and are assumed to be related to highly arid and hostile environmental conditions. Furthermore, associations were identified that have been unique and only occurred for a limited time span. For these associations, it was most important to see whether their occurrence has been regionally consistent. Therefore, assemblages that presumably occurred simultaneously in all three sections (according to similar malacozones) were correlated in Fig. 2.8. Six of these malacozones, comprising Cryptella Zone (MZ A), Obelus Zone (MZ B), Cochlicella Zone (MZ C), Lower and Upper Pomatias Zone (MZ E(a), MZ E(b)) and the Rumina Zone (MZ H) appeared to be consistent over the studied sequences (see Fig. 2.8). When merging the mollusc record with the lithostratigraphic results of Roettig et al. (2017), there are coincidences between certain gastropod assemblages and particular lithological units in all three sections. Moreover, these conformities between specific gastropod assemblages and lithological units apply for consistent periods as shown in Fig. 2.8.

Our results furthermore revealed, that associations dominated by Obelus pumilio always occur within the upper part of lithological Unit 12 (Fig. 2.9) and in Encantado additionally within the lower part of the subsequent layer 11. Accordingly, the Obelus Zone refers to a period about 360 ±30 ka to 340 ±30 ka, coincident with marine isotope stage (MIS) 10. The Cochlicella Zone is limited to lithological units 12, 10 and 11. These units yielded an age of about 340 ±30 to 300 ±30 ka, corresponding to the lower MIS 9. Furthermore, there are solitary occurrences of Cochlicella n. sp. in the uppermost part of the section Encantado (sample 26) and in the lithological Unit 9 at the section Melián (Fig. 2.9). We assume that these occurrences were caused by reworking, as both sequences show strong features of relocation. In that sense Roettig et al. (2017) reported a high abundance of relocated coated brood cells (nests of soil nesting bees) and a truncated paleosol on top of Unit 9. The Lower Pomatias Zone (MZ E(a)) is related to lithological unit 9 (Fig. 2.9). Moreover, the Upper Pomatias Zone (MZ E(b)) is coincident with lithological unit 7 and partly with lithological unit 6 (in section Encantado). MZ E(a) is separated from MZ E(b) by accumulations that testify hostile conditions evidenced by

23 severe species poverty. These accumulations are coincident with lithological unit 8 and the lower part of lithological unit 7. As Pomatias aff. lanzarotensis and also further faunal components of MZ E(a) reoccur in malacozone E(b) again (see Fig. 2.3), it might be an option that they outlasted hostile conditions in nearby refuges. Because of the resemblance between the species compositions of the Upper and Lower Pomatias Zones in section Encantado, we suggest that hostility was not predominantly triggered by climate. Whereas we presume stress by vigorous local accumulations of sand and intense volcanogenic fallout deposition. Furthermore, stronger local differences appear for lithological unit 6 (Fig. 2.8). Whereas unit 6 in section Encantado is related to malacozone E(b), in section Melián this unit corresponds to the Rumina-Caracollina Zone (MZ G). Altogether, deposits with high abundances of Pomatias aff. lanzarotensis are assumed to coincide with a period about 300 ±30 ka to 130 ±30 ka ago, comprising the marine isotope stages 7 to 9a. At section Jable, the lithological units 7-10 are dominated by features of relocation. Accordingly, it is challenging to work out a correlation of lithological units and gastropod associations. This is aggravated by only two available gastropod samples of that section which allow no substantive interpretation so far. Late Pleistocene deposits in the investigated sections are mainly characterised by the presence of Rumina decollata that is related to MZ H, but also to MZ G in section Melián (lithological units 6 to 1) (Fig. 2.9), probably corresponding to marine isotope stage 5. Within this general conformity between specific gastropod assemblages and lithological units, microhabitat differences appear between different localities, modifying the associations. Nevertheless, for the investigated sequences, it seems feasible to use gastropod assemblages with prominent occurrences of Rumina decollata, Pomatias aff. lanzarotensis, Cochlicella n. sp. and Obelus pumilio as marker associations that are representative for specific environmental phases. Thus, the distribution of these marker associations appears to be very valuable for stratigraphic classifications as suggested by Fuhrmann (1973), Kerney (1977), and Ložek (1982 & 1990). Figure 2.9 shows the transfer of the most stratigraphically indicative species to the standard stratigraphic profile compiled in Roettig et al. (2017). The presented malacological key species turned out to be highly useful for stratigraphic orientation in the field. Since the presence and manifestation of specific layers and palaeosurfaces in the study area is strongly dependent on the relief and local differences (Roettig et al., 2017), it is occasionally difficult to recognize standard patterns even over short distances. Locating abundant key species in a lithological unit can therefore serve as provisional indication for a stratigraphic classification whereas other proxies might require extensive laboratory analyses. However, for a reliable identification of malacozones it is necessary to consider the whole species association combined to a reproduceable sampling technique in order to distinguish between unrepresentative and

24 significant occurrences of key species within an assemblage. ithological unit 7. As Pomatias

Fig. 2.8 Correlation of the sequences Jable, Encantado and Melián based on malacozones (for coloured figures we refer to the web version of the article)

aff. lanzarotensis and also further faunal lower

among the studied

Obelus pumilio

n. sp. and

Cochlicella

l., 2017 l., (b).

lanzarotensis

aff.

Pomatias , ,

Rumina decollata

Distribution of the four key species

nces(a) subsequently and applied the to standard stratigraphy from Roettig a et .

Fig. seque

2.5.2 Derivation of palaeoconditions from species demands & community palaeoecological indicators

The modern gastropod fauna of Fuerteventura shows high endemism due to the islands´ isolated location. During glacial periods, sea level low stands resulted repeatedly in the emergence of a land bridge that connected Fuerteventura and the island of Lanzarote. Accordingly, both islands show a high accordance of species. Nevertheless, investigations revealed that two thirds of all endemic species of the Canary Islands are endemic to

Fuerteventura (Alonso & Ibáñez, 2005). At least half of these endemic species live on Jandia Peninsula which is geographically isolated from the north of the island by the isthmus “Isthmo de la Pared” (Fig. 2.10). The isthmus that includes the sand dessert “El Jable” represents a nearly insuperable barrier for gastropods (Alonso & Ibáñez, 2005). Gastropods can rarely be found at the study area today. Only few species occur and live in the depth contours of Wadis, where increased edaphic humidity enhances vegetation growth. Most of the species included in the fossil record recently live in other regions or on

other islands of the archipelago. Several species, e.g. Cochlicella n. sp., Hemicycla n. sp., Ferussacia n. sp. and Obelus pumilio are even extinct at the Canary Islands according to the recent state of knowledge. The modern absence of species is dominated by habitat loss due to human activities (see Rodriguez et al., 2005). Nevertheless, prehistoric shifts in distribution ranges of species were predominantly related to environmental forces. Modern gastropod species on Fuerteventura are mainly distributed to the windward sides of mountain ranges and

Fig. 2.10 Species richness of modern terrestrial gastropods on Fuerteventura (left) presumably influenced by the relief (right) (Source: left: modified from Alonso & Ibáñez, 2005; right: maps.google.de).

27 higher altitudes (see Alonso & Ibáñez, 2005). Due to their lower elevations, the eastern Canary Islands are hardly affected by humidity brought by the trade winds. Thus, the vegetation is primarily composed of xerophilous plants (Juan et al., 2000). Nevertheless, trade winds might exert at least little influence on higher regions due to increasing orographic humidity. The highest elevation on Fuerteventura is the Pico de la Zarza (807 m a.s.l.), which is located on Jandia Peninsula. The highest regions of Jandia show local hygrophilous endemism (Juan et al., 2000) and seem to be relictic hotspots. Thus, recent gastropod species on Fuerteventura seem to be attracted by increased humidity. Accordingly, we assume higher humidity as an important factor for past increases in biodiversity.

Tab. 2.1 Gastropod species prevalent in the fossil record and their ecological demands.

Modern biogeographic distribution Ecological demands

Canariella plutonia widespread on Fuerteventura and Lanzarote lives in dry temperate shrub vegetation (Lowe, 1861) including the smaller islands in the north (Groh & Neubert, 2011a); prefers rocky (Alonso & Ibáñez, 2005) and stony places; even occurs in areas of badlands (Alonso & Ibáñez, 2005)

Candidula ultima n. Candidula ultima is endemic to lives exclusively on sand dunes with ssp. (Mousson, 1872) Fuerteventura (Alonso & Ibáñez, 2005) and meagre grass vegetation (Groh & Lanzarote (Groh & Neubert, 2011b); on Neubert, 2011b); well adapted to live in Fuerteventura, living specimens are only sun-exposed areas, due to their white known from the Isthmo de la Pared with an coloured shells which reflect sunlight area of occupancy of 4 km2 (Groh & (Alonso & Ibáñez, 2005) Neubert, 2011b). Subfossil shells presumably correspond to a separate morpho(sub)species. Caracollina lenticula distributed over all of the Canary Islands typically associated with thermophilic (Michaud, 1831) (Bank et al., 2002) as well as over the Near species; they hide under rocks, trunks, in East to Europe and the Central Atlantic cracks and walls (Ruiz Ruiz et al., 2006), Islands (Welter-Schultes, 2012) also between plants and in soil substrate (Welter-Schultes, 2012), often behind dunes or at rocky coasts in dry habitats and are occasionally found in gardens and greenhouses (Welter-Schultes, 2012) Cochlicella n. sp. extinct; the only modern representative of Related species (C. barbara, C. acuta) (Yanes et al., 2004) the genus living on the Canary Islands is live in sandy and dry habitats in coastal Cochlicella barbara (Bank et al., 2002), vicinity and are frost sensitive (Welter- which is not identical to Cochlicella n. sp.; Schultes, 2012) Cochlicella n. sp. has been discovered by Yanes et al. (2004) and was found fossil in Quaternary deposits at Barranco Encantados and Cantera de Melián

Cryptella auriculata endemic to Fuerteventura (Bank et al., nocturnal; visible at daytime only after (Mousson, 1872) 2002), there it lives everywhere north of rain; they prefer moderate conditions Isthmo de la Pared (Alonso & Ibáñez, 2005) and hide under stones and in rock crevices; the animals can reach up to over 6 cm in length (Alonso & Ibáñez, 2005); the internal shell of the genus Cryptella consists of calcite (Hutterer, 1990b; Yanes et al., 2013)

Ferussacia valida endemic to Fuerteventura, there it lives on ground-dwelling; found under stones in (Mousson, 1872) the higher elevations of Jandía Peninsula in lichen-rich rocky environments with very an area of 6 km2, whereat living specimens sparse low shrub vegetation; distribution are rare (Groh, 2017a) area lies at the crest and on north-facing slopes in humid microhabitats (Groh, 2017a) Granopupa granum lives on Fuerteventura, Southern Gran often very abundant; prefers dry and (DRAPARNAUD, Canaria and Lanzarote (Alonso & Ibáñez, sunny habitats; in Switzerland at south- 1801) 2005); also distributed over Morocco to exposed slopes in up to 1400 m altitude Tunisia, Portugal, Middle Europe to Arabia, (Welter Schultes, 2012); the species Afghanistan and Ascension Island (Atlantic) lives at the ground below limestone (Bank et al., 2002) rocks and in crevices (Welter Schultes, 2012) as well as in leaf litter of scrub or other semi-sheltered habitats (Giusti et al., 1995) Hemicycla n. sp. Presumably extinct Unknown; associated with Cochlicella n. sp., Ferussacia valida and Hemicycla cf. paeteliana

Hemicycla cf. Hemicycla paeteliana is endemic to the Hemicycla paeteliana is a ground- paeteliana (Pfeiffer, mountainous regions of Jandia on dwelling species and is found in 1859) Fuerteventura (Groh & Alonso, 2011) montane Canary island vegetation under rocks, in crevices and feeds on lichens (Groh & Alonso, 2011) Hemicycla sarcostoma endemic to the Eastern Canary Islands, lives in dry temperate shrub vegetation (Webb & Berthelot, widespread on Fuerteventura, Lanzarote, (Groh & Neubert, 2011c); prefers rocky 1833) Isla de Lobos, La Graciosa and Isla and stony habitats (Alonso & Ibáñez, Montana Clara (Fischer, 2003b; Alonso & 2005); high morphologic variability Ibáñez, 2005) (Fischer, 2003b) Monilearia monilifera endemic to Fuerteventura and Lanzarote, lives in dry temperate shrub vegetation (Webb & Berthelot, there it is widespread (Groh & Neubert, (Groh & Neubert, 2011d) 1833) 2011d)

Obelus pumilio extinct on Fuerteventura and Gran Canaria; Unknown; in Morocco O. pumilio lives in (Dillwyn, 1817) recent living in Morocco (Ibáñez et al., 2003; cold semi-arid climates (type "BSk" Alonso & Ibáñez, 2005) Köppen-Geiger) Cold semi-arid climates. The distribution area is characterized by mild climate: Maximal average temperatures in summer do not exceed 22.6°C and minimum average temperatures do not fall below 10.4°C

Obelus cf. unknown; the species Obelus unknown; O. discogranulatus lives in discogranulatus discogranulatus is endemic to Fuerteventura shrub dominated psammophilous where it is restricted to a small area of the vegetation (Groh & Alonso, 2013) eastern Jandia Mountains (Groh & Alonso, 2013) Pomatias aff. P. lanzarotensis is recorded for Lanzarote, unclear; ground-dwelling, lanzarotensis La Graciosa and Fuerteventura (Bank et al., On Fuerteventura, this species is mostly (Wollaston, 1878) 2002; Alonso & Ibáñez, 2005). As generally found in lower elevations in open only shells but no living animals are found habitats and on mountain slopes, mostly (Fischer, 2003b & 2003c; Fischer & hidden under stones. As living animals Hunyadi, 2008), it is unclear if modern are rare, it is unclear if these habitats are populations are extant or not. The species representative biotopes or rather on Fuerteventura has a wider umbilicus, (sub)fossil deposits. wider shell shape and differentiated shell The related species Pomatias elegans is sculpture compared to the specimens on known to survive drought periods of Lanzarote. “The taxonomy for these species several month. For opening the is confused and the group is in urgent need operculum, a minimum relative humidity of a major revision, whereat such a revision of 95% is needed, snails cannot get is severely limited by a lack of living active when being submerged under material” (Groh, 2017b) water (Welter Schultes, 2012)

Rumina decollata widespread on Fuerteventura, Gran dry open habitats among shrub or gravel (Linnaeus, 1758) Canaria, Tenerife and Lanzarote (Bank et on calcareous soils (Kerney et al., 1983); al., 2002); also lives in Northern Africa and widespread in the Mediterranean Southern Europe (Welter-Schultes, 2012) (Kerney et al., 1983); sometimes in shady places, in the soil or under stones (Welter-Schultes, 2012), carnivore, especially snail-eating Rumina saharica Presumably subfossil for the Canary Natural habitats unknown, sympatric (Pallary, 1901) Islands, today lives in Northern Africa, with Rumina decollata (Bank & Eastern and Southern Mediterranean (Bank Gittenberger, 1993) & Gittenberger, 1993)

Theba spp. indet. individuals have not been identified to Theba lives in very hot and dry places, species level due to their bad preservation at extreme heat they climb up leaves and frequent coatings; species might and stems to ventilate and escape the probably include: ground heat (Alonso & Ibáñez, 2005); lives in dry temperate shrub vegetation (Groh & Neubert, 2011e & 2011f)

Theba geminata which is most probably a species complex (Mousson, 1857) (Greve et al., 2010) and recently distributed on all Canary Islands (Greve et al., 2010)

Theba cf. arinagae only known living at the summit of the (Gittenberger & volcano north of Arinaga (Gran Canaria), Ripken, 1987) where it occupies a narrow strip of rocky habitats above the sandy slopes (Alonso & Groh, 2013); found fossil/subfossil on Fuerteventura (Yanes et al., 2004; Castillo et al., 2007)

Theba costillae known from the Pleistocene of (Hutterer, 1990) Fuerteventura (Hutterer, 1990a; Hutterer et al., 2010) Theba clausoinflata Modern distribution on Jandia Peninsula on (Mousson, 1857) Fuerteventura (Greve et al., 2010; Groh & Neubert, 2011e) Theba impugnata The species is restricted to the (Mousson, 1857) northeastern part of Lanzarote and the adjacent islet of La Graciosa. (Groh & Neubert, 2011g)

Theba n. spp. Two new types have been recognized which refer to solely fossil shells (comp. Tab. 2.8) Xerotricha Endemic to the Eastern Canary Islands, lives in dry temperate shrub vegetation; lancerottensis (Webb where it is widespread (Alonso & Ibáñez, shell covered with hairs (Alonso & & Berthelot, 1833) 2005; Groh & Neubert, 2011f) Ibáñez, 2005)

For nowadays occurring species, palaeoecological conditions can be derived from their modern ecological demands. However, the available literature about ecological demands of eastern Canary gastropod species is quite scarce, as most of these species are endemic and have been rarely studied yet. Furthermore, many species have very similar distribution areas.

Thus, it is difficult to identify differences in their ecological dependencies. Nevertheless, the results of a cluster analysis (Chap. 2.4.4) yielded seven different groups of gastropod species, which show very similar distribution patterns within the sequences. We assume, that clustered species most probably shared related ecological demands. Clustering here is independent of malacozonation, as e.g. omnipresent species with a high tolerance range generally did not contribute to the definition of malacozones, but represent an own ecological group. For more detailed information on respective gastropod species, we refer to Table 2.1.

Obelus pumilio group

Obelus pumilio is presumably adapted to very specific environmental conditions, as cluster analysis yielded no species with similar distribution patterns and related ecological demands respectively. Obelus pumilio is presently extinct on the Canary Islands, but still lives in a small coastal distribution area in Morocco (Ibáñez et al., 2003; Alonso & Ibáñez, 2005) between Agadir and Essaouira. This area refers to a constrained area of cold semi-arid climate (according to Köppen-Geiger, Fig. 2.11). Most probably, this species is adapted to very mild arid conditions and does not tolerate hotter summers. Due to this temperature sensitivity, we assume Obelus pumilio to be a valuable indicator for palaeo climate.

Fig. 2.11 The map shows the effective climate classification by Köppen- Geiger for the modern distribution area of Obelus pumilio, whereat the species occurs in the small Moroccan patch between Agadir and Essaouira, which corresponds to a cold semiarid climate (Source: modified from PEEL et al., 2007). Legend: BWh - hot desert, BWk - cold desert, BSh - hot steppe, BSk - cold steppe, Csa - temperate with hot and dry summer, Csb - temperate with dry and warm summers

Rumina decollata group

This group includes Caracollina lenticula, Granopupa granum and Rumina decollata. These three species are widely distributed over the Canary Islands, Northern Africa and Southern

Europe. There they share almost similar distribution areas (see Welter-Schultes, 2012). In Europe, these species occur only on the coastal margin related to Mediterranean climate. Most probably, these species are highly adaptable and robust against heat stress. They primarily life in dry and sunny places and occur only in coastal settings. This ecological group is supposed to be strongly thermophilous, and related species tolerate hot dry summers but only mild winters.

Theba spp. indet. group

This group contains Theba spp. indet. and Monilearia monilifera. These two taxa dominate nearly all taphocoenoses of the study site. Furthermore, abundances of Theba spp. indet. show an inverse correlation with gastropod biodiversities. This is indicated by a negative correlation coefficient (r) for Theba abundances versus gastropod biodiversity that is -0.37. High abundances and mass occurrences of only few species coupled to decreased biodiversity (low equitability) usually signify unstable or stressed ecosystems (see Magurran, 1988). This phenomenon is caused by highly adaptable species, which, under changing conditions or environmental stress, quickly occupy all new available niches. In the studied gastropod associations, Theba spp. indet. and to some degree Monilearia monilifera proved to be the most adaptive and robust taxa, that were able to survive even extreme environmental conditions. Beside climatically induced heat stress, these conditions may also include a sudden overabundant sediment input as indicated in Encantado sample 10 (Fig. 2.8) or strong volcanogenic influence as assumed for samples 14 and 15 in section Encantado.

Pomatias aff. lanzarotensis group

Ecological demands for Canariella plutonia and Pomatias aff. lanzarotensis are hardly known. Canariella plutonia is endemic to Lanzarote and Fuerteventura, whereas the recent status of Pomatias aff. lanzarotensis is unclear (comp. Tab. 2.1). However, lithostratigraphic features of the imbedding sediment (lithological unit 9, compare Fig. 2.8) include small channels and increased abundances of Pomatias aff. lanzarotensis may indicate a higher adaption of the species to strong rain events and related ephemeral floods. These conditions may have been associated with a general increase in occasional rainfalls under arid boundary conditions. Therefore, evidence is also given by the fact that P. lanzarotensis is the only recorded taxon

32 with an operculum enabling the species to protect itself against desiccation as well as rain floods.

Cochlicella n. sp. group

This group includes Cochlicella n. sp., Cryptella auriculata and Ferussacia valida. All of these species are endemic to the eastern Canary Islands and ecological demands are hardly known. Cochlicella n. sp. is presently extinct. Related species of the genus Cochlicella are frost sensitive. Possibly Cochlicella n. sp. was adapted to warmer temperatures compared to those tolerated by Obelus pumilio. Furthermore, strong ephemeral rainfalls in MZ E(a) (Fig. 2.8) might have caused the extinction of Cochlicella n. sp. Cryptella auriculata today is distributed everywhere north of Isthmo de la Pared on Fuerteventura. The modern distribution of Ferussacia valida is reduced to humid microhabitats at the highest regions of Jandia Peninsula (see Tab. 2.1). Relating to the studied sections, the presence of Ferussacia valida thus indicates comparatively more humid climatic conditions (comp. Fig. 2.12).

Hemicycla spp. group

This ecological group consists of several species of the genus Hemicycla. For the studied sections on Fuerteventura, this genus persisted over the past approximately 320 ka and survived changing climatic conditions in nearby refuges. As it outlasted hostile conditions in more favourable microhabitats at the island (e.g., moister valley floors), the genus is assumed to be highly tolerant to climatic changes. The included species which is most frequently represented among the samples is Hemicycla paeteliana, whose modern population is reduced to a small patch of montane vegetation at the highest regions of Jandia peninsula. The species is adapted to humid microhabitats and indicates a distinct vegetation cover. Hemicycla cf. paeteliana and related undermined specimens of the genus Hemicycla correlate with the presence of palaeosurfaces and increased gastropod biodiversities.

Candidula ultima n. ssp. group

This group includes only C. ultima. This species is currently distributed in the sand desert of Isthmo de la pared, and restricted to sand dunes with meagre grass vegetation.

The above-described ecological groups (related to malacozones) show that the study area was characterised by alternating periods of very different environmental conditions.

Furthermore, not only autecological (between individuals and environment), but also syn- ecological factors (within biocoenoses) and the distance of the studied sections to potential species refuges during hostile conditions may have influenced the gastropod associations. In turn, these factors are driven by the persistence of environmental conditions within an ecosystem. Finally, we assume predominant ecological groups that are limited to a specific

Fig. 2.12 The most complete sequence Encantado plotted with malacozonation and environmental conditions. The arrows on the left side mark presumed fundamental climatic changes. Reddish sections mark phases of increased dust accumulation. High biodiversity, low breakage rates, and the occurrence of the gastropod taxa Hemicycla cf. paeteliana/ spp. indet. indicate geomorphologically stable phases in combination with a distinct vegetation cover. (for coloured figures we refer to the web version of the article)

34 period in time and stratigraphic position such as the Obelus pumilio group, the Rumina decollata group, the Pomatias aff. lanzarotensis group and the Cochlicella n. sp. group to reflect the dominating environmental conditions. Thereby changes of the predominant ecological group suggest fundamental changes in environmental conditions related to climatic shifts. The remaining three ecological groups that are the Candidula ultima n. ssp. group, the Hemicycla spp. group and the Theba spp. indet. group are presumed to be more tolerant to changing environmental conditions because they repeatedly reoccurred through time. Members of the Theba spp. indet. group characterise the fauna during phases of increased stress. On the opposite, Hemicycla spp. seems to have outlasted in moister valley floors until the conditions were recovered to re-enlarge the species distribution area again. When the palaeoenvironmental conditions that were derived from malacological information are transferred to the chronological frame based on IRSL dating (see Roettig et al, 2017; Fig. 2.8), relations become evident as follows. (Ι) For deposits of a presumed age of around 360 ±30 ka to 340 ±30 ka, the presence of Obelus pumilio indicates colder and semi-arid conditions. (II) Around 340 ±30 ka ago, the faunal composition related to the Cochlicella Zone gives evidence of increasing temperature leading to moderate and somehow dryer conditions. (III) Around 300 ±30 ka ago, a further strong environmental change could be document leading to temporarily more humid conditions as evidenced by the occurrence of Pomatias aff. lanzarotensis. Here, a framed period showing the absence of all species apart from Theba indet. and Monilearia monilifera may indicate serious environmental stress, assumingly due to the substantial input of volcanogenic material. (IV) A last environmental shift including an increase in temperature and aridity around 130 ka ±30 ago is indicated by Rumina decollata and related faunal components within the Rumina Zone. These climatic shifts in combination with associated palaeoenvironmental conditions are shown in Fig. 2.12.

Furthermore, it is conspicuous that the succession of presumed climatically triggered malacozones is not always in agreement with the succession of the lithological units (sandy layers alternating with palaeosurfaces) (see Fig. 2.12). Usually, soil formation is linked to enhanced humidity, and it is quite conceivable that malacozones should be fundamentally biased by the presence of a lastingly stable palaeosurface, bearing climatic impact in mind. However, especially malacozones MZ C and MZ E(b) (Fig. 2.12) provide good examples that specific ecological groups persisted several tens of thousands of years, irrespective of whether or not a sand layer was deposited or a palaeosurface was formed. Even though, such stratigraphic changes were accompanied by changes in the abundances of individuals, they have not been accompanied by fundamental changes in the species composition. Therefore, we suggest that the succession of sand layers and palaeosurfaces was not necessarily related to stronger climatic changes as long as respective lithological units correspond to the same

35 malacozone. Hence, these results partly support the concept of climatically independent palaeosurface formation, e.g. described by Faust et al. (2015). However, there are other examples, like Malacozone MZ E(a) in lithological unit 9 that apparently show a relation between specific climatic conditions and palaeosurface formation. In some cases (e.g. Unit 9) palaeosurface formation on northern Fuerteventura was obviously related to climatic and environmental changes, but in a number of cases we do not see that relation. Therefore, we assume, that respective stratigraphic changes were probably not primarily related to climate forcing, but instead biased by multiple factors such as local sediment availability and dust input (compare Roettig et al., 2018). Nevertheless, strongly developed palaeosurfaces involved favourable conditions for gastropods as indicated by high gastropod biodiversity and frequent occurrences of Hemicycla cf. paeteliana (Fig. 2.12), both indicating a distinct vegetation cover. According to the above-mentioned concept of climatically independent palaeosurfaces, it may be an option that these favourable conditions were mainly caused by increased edaphic humidity. This edaphic humidity, in turn, resulted from enhanced water-storage capacity caused by higher silt (dust) contents in palaeosurfaces. Therewith, geomorphological stability accompanied by favourable substratum promoted plant growth and biological activity and may have enabled soil-like ecosystems under more or less unchanged climatic conditions.

2.5.3 Morphogenic aspects derived from taphonomic features

The state of preservation of shells in taphocoenoses can implicate particular syn- or post- sedimentary processes. That becomes especially valuable in order of a distinction between phases of geomorphological stability and activity, while the latter is generally indicated by the reworking of sediments. The grade of shell breakage as well as the presence of shell coating serve as measure for the reworking of material, respectively for the transport distance of gastropod shells before their deposition. The breakage ratio (Chap. 2.3.3) was exclusively calculated for the genus Theba, in order to ensure the comparability of this index independently from differing shell fragilities of different species. Shells with high breakage rates are supposed to be allochthonous and transported over a longer distance before deposition. Lower shell breakage such as in Melián samples 3, 7, 9-10 and 13, and Encantado samples 5, 12, 18 to 20 and 25, is assumed to be related to rather stable conditions and limited reworking. Our results show lower breakage rates in palaeosurfaces (see Figs. 2.6 and 2.12), thus, pointing to more stable conditions. Increased breakage rates are related to the base of lithological units which are dominated by pure unconsolidated sands. This linkage testifies the onset of new phases of sediment input. Higher breakage ratios in facies related to palaeosurfaces such as at Encantado sample 11 or Melián samples 6, 12 and 27 (Fig. 2.6) might in turn point to the reworking of silty sediments, in contrast to permanently stable conditions. Altogether, the

36 higher average breakage rate in section Melián compared to section Encantado (see Chap. 2.4.4) indicates higher instability and an increased grade of reworking for sediments at the location of Melián. We assume that this is mainly caused by a more pronounced relief and the greater proximity of the section Melián to the local erosion base (comp. Roettig et al., 2017). The coating rate (Chap. 2.3.3) shows an inverse relation to the breakage rate (see Fig. 2.6) bearing fewer shell coatings during phases of reactivated sediment input. In palaeosurfaces initial soil formation may have taken place characterised by short mobilization of clay and calcium carbonate causing the prevalent shell coatings.

2.6 CONCLUSIONS

Malacological studies were conducted on aeolianite-palaeosol sequences on northern Fuerteventura. These investigations revealed that gastropod communities on northern Fuerteventura significantly changed through time, indicating changes in environmental conditions. The investigated sequences could be subdivided into eight different malacozones. Four of them, Pomatias Zone, Cochlicella Zone, Rumina Zone and Obelus Zone proved to be clearly attributable to particular lithological units and can be consistently found in the study area. These key associations may allow using gastropod records in order to obtain a provisional stratigraphical and chronological classification of sediments on Fuerteventura. Evidences of palaeoenvironmental conditions for each malacozone could be derived from species demands and community palaeoecological indicators. They are assumed to reflect local climate conditions and point to cold and semi-arid conditions related to the Obelus pumilio fauna (about 360 ±30 ka to 340 ±30 ka); a subsequent temperature rise presumably around 340 ±30 ka leading to moderate dry conditions within the Cochlicella Zone; a further strong climatic change at around 300 ±30 ka leading to temporarily more humid conditions related to the Pomatias aff. lanzarotensis Zone, and a further temperature increase to hot and arid conditions for the Rumina decollata Zone that comprises the Late Pleistocene.

Furthermore, our results revealed that the alternating succession of sand layers and palaeosurfaces (reddish silty units) is partly not in conformity with the succession of malacozones. This means that in some cases palaeosurfaces may reflect stable and probably more humid environmental conditions. In other cases, there was apparently no relation between palaeosurface formation and local climatic conditions. However, almost all palaeosurfaces show increased gastropod biodiversity and are primarily linked to the presence of Hemicycla cf. paeteliana, indicating a distinct vegetation cover. In case of unconformities between stratigraphic succession and malacozonation, we assume that the favourable conditions that were linked to silty reddish units (palaeosurfaces) may have corresponded to edaphic moisture rather than to climatically induced humidity.

Moreover, decreased snail shell breakage and higher coating rates substantiate palaeosurface formation during geomorphologically stable phases. In turn, high breakage rates and decreased coating point to reworking and colluviation of the imbedding sediment.

Finally, the record of gastropod assemblages provides a high potential for reconstructing changes in palaeo environmental conditions and to differentiate between periods dominated by changes in edaphic moisture and periods dominated by changes in climatic conditions.

2.7 ACKNOWLEDGEMENT

We want to thank Prof. Dr. Yurena Yanes for the help concerning the determination of Canary gastropod species, as well as Prof. Dr. Jörg W. Schneider for the helpful advices and discussions. Furthermore, we are grateful to Philipp Baumgart and Florian Schneider for support in the fieldwork. We sincerely thank the two anonymous reviewers and the editor for their advices and help, that significantly improved the quality of the manuscript.

Funding: This work was supported by the German Research Foundation (DFG, FA 239/18-1) and the Society of Friends and Supporters of the TU Dresden. Furthermore, the work of the first author was financed through the Dr.-Erich Krüger foundation (University of Mining and Technology, Freiberg) and a Graduate research fellowship of the Dresden University of Technology.

2.8 REFERENCES

Alonso, M. R. & IbáÑez, M. G. (2005). Fauna Terrestre: los Moluscos. In: Delgado, O. R. (ed): Património Natural de la isla de Fuerteventura. Cabildo de Fuerteventura, Consejería de Medio Ambiente y Ordenación Territorial del Gobierno de Canarias, Centro de la Cultura Popular Canaria, 377-384.

Bank, R. A. & Gittenberger, E. (1993). Neither Rumina truncata, nor R. gracilis, but R. saharica (Mollusca: Gastropoda Pulmonata: Subulinidae). – Zoologische Mededelingen 67: 525-527.

Bank, R. A., Groh, K. & Ripken, T. E. J. (2002). Catalogue and bibliography of the non-marine Mollusca of Macaronesia. In: Falkner, M., Groh, K. & Speight, M. C. D.. Collectanea Malacologica, Festschrift für Gerhard Falkner. Friedrich-Held-Gesellschaft München & ConchBooks Hackenheim, 89-235.

Bouab, N. & Lamothe, M. (1997). Geochronological framework for the Quaternary paleoclimatic record of the Rosa Negra Section (Fuerteventura, Canary Islands). In: Meco, J. & Petit-Maire, N. (Eds.): Climates of the Past. Fuerteventura and Lanzarote. UNESCO International Union of Geological Sciences, 37-42.

Castillo, C., Yanes, Y., Armas, F.R., Ibáñez, M., Alonso, M.R., Quesada, M.L., De La Nuez, J., Torres, T. & Ortiz, J.E. (2007). Eventos paleobiológicos del Cuaternario de Fuerteventura (Islas Canarias). In. Braga, J.C., Checa, A. & Company, M. (Eds.). XXIII Jornadas de la Sociedad Española de Paleontología. Libro de resúmenes. Instituto Geológico y Minero de España y Universidad de Granada, 13-14.

Coello, J. J., Castillo, C. & González, E. M. (1999). Stratigraphy, chronology, and palaeoenvironmental reconstruction of the quaternary sedimentary infilling of a volcanic tube in Fuerteventura, Canary Islands. Quat. Res. 52: 360–368.

Criado, C. & Dorta, P. (2003). An unusual ‘blood rain’ over the Canary Islands (Spain). The storm of January 1999. J. Arid Environ. 55: 765–783.

Criado, C., Torres, J. M., Hansen, A., Lillo, P. & Naranjo, A. (2011). Intercalaciones de polvosahariano en paleodunas bioclásticas de Fuerteventura (Islas Canarias). Cuat. Geomorfol. 26 (1–2): 73-88.

Damnati, B., Petit-Maire, N., Fontugne, M., Meco, J. & Williamson, D. (1996). Quaternary palaeoclimates in the eastern Canary Islands. Quat. Int. 31: 37-46.

Faust, D., Yanes, Y., Willkommen, T., Roettig, C., Richter, D., Richter, D., Suchodoletz, H. v. & Zöller, L. (2015). A contribution to the understanding of late Pleistocene dune sand-paleosol- sequences in Fuerteventura (Canary Islands). Geomorphology 246: 290-304.

Fischer, W. (2003a). Landschnecken aus Basalten südlich von Corralejo, Fuerteventura (Kanaren, Spanien). Club Conchylia Informationen 34(4/6): 43-45.

Fischer, W. (2003b). Über Hemicycla sarcostoma (Webb & Berthelot 1833) auf Fuerteventura und Lanzarote (Kanaren, Spanien). Club Conchylia Informationen 34(5/6): 49-51.

Fischer, W. (2003c). Über die Verbreitung von Pomatias cf. lanzarotensis (Wollaston 1878) auf Fuerteventura (Kanaren, Spanien). Club Conchylia Informationen 34(5/6): 47.

Fischer, W. & Hunyadi, A. (2008). Pomatias canariensis (Orbigny 1840) (Gastropoda: Prosobranchia: Pomatiidae) auf der Insel Gomera (Kanarische Inseln, Spanien). Nachrichtenblatt der Ersten Vorarlberger Malakologischen Gesellschaft, 15: 45-46.

Fuhrmann, R. (1973). Die spätweichselglaziale und holozäne Molluskenfauna Mittel- und Westsachsens. Freiberger Forschungshefte: Reihe C, Geowissenschaften, Paläontologie, Vol. 278, VEB Deutscher Verlag für Grundstoffindustrie, Freiberg.

Giusti, F., Manganelli, G. & Schembri, P.J. (1995). The Non-Marine Molluscs of the Maltese Islands. Monografie 15, Museo Regionale di Scienze Naturali, Torino, Italy, 607pp.

Greve, C., Hutterer, R., Groh, K., Haase, M. & Misof, B. (2010). Evolutionary diversification of the genus Theba (Gastropoda: Helicidae) in space and time: A land snail conquering islands and continents. Molecular Phylogenetics and Evolution, 57(2): 572-584.

Groh, K. (1985). Landschnecken aus quartären Wirbeltierfundstellen der Kanarischen Inseln (Gastropoda). Bonner zoologische Beiträge 36: 395‐415.

Groh, K. (2017a). Ferussacia valida. The IUCN Red List of Threatened Species 2017: e.T170842A1317476. http://dx.doi.org/10.2305/IUCN.UK.2017- 3.RLTS.T170842A1317476.en. Downloaded on 04 January 2019.

Groh, K. (2017b). Pomatias lanzarotensis. The IUCN Red List of Threatened Species 2017: e.T155672A734228. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T155672A734228.en.

Downloaded on 16 January 2019.

Groh, K. & Alonso, M.R. (2011). Hemicycla paeteliana. The IUCN Red List of Threatened Species 2011: e.T156847A5006683. http://dx.doi.org/10.2305/IUCN.UK.2011- 1.RLTS.T156847A5006683.en. Downloaded on 16 January 2019.

Groh, K. & Alonso, R. (2013). Obelus discogranulatus. The IUCN Red List of Threatened Species 2013: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T156713A4987021.en. Downloaded on 28 October 2015.

Groh, K. & Neubert, E. (2011a). Canariella plutonia. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T156902A5014597.en. Downloaded on 02 November 2018.

Groh, K. & Neubert, E. (2011b). Candidula ultima. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T156397A4938108.en. Downloaded on 02 November 2018.

Groh, K. & Neubert, E. (2011c). Hemicycla sarcostoma. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T156447A4946261.en. Downloaded on 28 October 2015.

Groh, K. & Neubert, E. (2011d). Monilearia monilifera. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T157203A5054222.en. Downloaded on 28 October 2015.

Groh, K. & Neubert, E. (2011e). Theba clausoinflata. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T156405A4940299.en. Downloaded on 28 October 2015.

Groh, K. & Neubert, E. (2011f). Xerotricha lancerottensis. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T156944A5019570.en.

Downloaded on 28 October 2015.

Groh, K. & Neubert, E. (2011g). Theba impugnata. The IUCN Red List of Threatened Species 2011: http://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T157120A5040107.en. Downloaded on 02 November 2018.

Hutterer, R. (1990a). A new Canarian Theba (Gastropoda: Helicidae) with African affinities. – Schriften zur Malakozoologie aus dem Haus der Natur - Cismar 3: 1-6

Hutterer, R. (1990b). Recent and fossil slugs of the genus Parmacella in the Canary Islands, with the description of three new species. – Archiv für Molluskenkunde 120 [1989](1-3): 73-93.

Hutterer, R., Greve, C. & Haase, M. (2010). Three species of Theba (Gastropoda: Helicidae) from a Pleistocene dune in SW Morocco. Journal of Conchology 40(2): 121.

Ibáñez, M., Alonso, M.R., Groh, K. & Hutterer, R. (2003). The genus Obelus Hartmann, 1842 (Gastropoda, Pulmonata, Helicoidea) and its phylogenetic relationships. Zool. Anz. 242: 157- 167.

Juan, C., Emerson, B.C., Oromi, P. & Hewitt, G.M. (2000). Colonization and diversification: towards a phylogeographic synthesis for the Canary Islands. Trends Ecol. Evol. 15: 104-109.

Kerney, M. P. (1977). A Proposed Zonation Scheme for Late-glacial and Postglacial Deposits Using Land Mollusca. Journal of Archaeological Science 4: 387-390.

Kerney, M. P., Cameron, R. A. D. & Jungbluth, J.H. (1983). Die Landschnecken Nord- und Mitteleuropas. Verlag Paul Parey, Hamburg/Berlin, 384 pp.

Limondin‐Lozouet, N. & Preece, R. C. (2004). Molluscan successions from the Holocene tufa of St Germain‐le‐Vasson, Normandy (France) and their biogeographical significance. Journal of Quaternary Science 19(1): 55-71.

Limondin-Lozouet, N., Villa, V., Pereira, A., Nomade, S., Bahain, J. J., Stoetzel, E. Aureli, D. & Nicoud, E. (2017). Middle Pleistocene molluscan fauna from the Valle Giumentina (Abruzzo, Central Italy): Palaeoenvironmental, biostratigraphical and biogeographical implications. Quaternary Science Reviews 156: 135-149.

Ložek, V. (1964). Quartärmollusken der Tschechoslowakei. Rozpravy Ústøedního ústavu geologického 31, 376 pp., Prag.

Ložek, V. (1982). Faunengeschichtliche Grundlinien zur spät- und nacheiszeitlichen Entwicklung der Molluskenbestände in Mitteleuropa. Rozpr. Ceskoslov. Akad. Ved., 92(4), 106 pp., Prag.

Magurran, A. E. (1988). Ecological Diversity and Its Measurement. Princeton University Press, p. 7-45, Princeton.

Mania, D. (1973). Paläoökologie, Faunenentwicklung und Stratigraphie des Eiszeitalters im mittleren Elbe-Saalegebiet auf Grund von Molluskengesellschaften. Geologie, Beiheft 78/79: 1-175, Berlin.

Meco, J. & Pomel, R. (1985). Les formations marines et continentales intervolcaniques des Iles Canaries orientales (Grande Canarie, Fuerteventura et Lanzarote): Stratigraphie et signification paléoclimatique. Estud. Geol. 41: 223–227.

Meco, J., Petit-Maire, N., Fontugne, M., Shimmield, G. & Ramos, A. J. (1997). The Quaternary deposits in Lanzarote and Fuerteventura (Eastern Canary Islands, Spain): an overview. In: MECO, J. & PETIT-MAIRE, N. (Eds.): Climates of the Past, Proceedings of the CLIP Meeting held in June 2–7, 1995 Lanzarote und Fuerteventura (Canary Islands, Spain). IUGS-UNESCO, Las Palmas de Gran Canaria, 123–136.

Meco, J. (Ed.), Betancort, J., F., Ballester, J., Fontugne, M., Guillou, H., Scaillet, S., Lomoschitz, A., Cilleros, A., Carracedo, J., C., Petit-Maire, N., Ramos, A., Perera-Betancort,

M., A., Soler-Onís, E., Medina, P. & Montesinos, M. (2008). Historia Geológica del Clima en Canarias. Las Palmas de Gran Canaria.

Moine, O., Rousseau, D. & Antoine, P. (2005). Terrestrial molluscan records of Weichselian Lower to Middle Pleniglacial climatic changes from the Nussloch loess series (Rhine Valley, Germany) - the impact of local factors. Boreas, Vol. 34: 363-380.

Moine, O., Rousseau, D. D., Antoine, P. (2008). The impact of Dansgaard-Oeschger cycles on the loessic environment and malacofauna of Nussloch (Germany) during the Upper Weichselian. Quaternary Research 70(1): 91-104.

Morisita, M. (1959). Measuring of the dispersion and analysis of distribution patterns. Memoires of the Faculty of Science, Kyushu University, Series E. Biology 2: 215–235.

Muhs, D.R. (2013). The geologic records of dust in the Quaternary. Aeolian Res. 9: 3–48.

Ortiz, J., E., Torres, T., Yanes, Y., Castillo, C., De La Nuez, J., Ibáñez, M. & Alonso, M., R. (2006). Climatic cycles inferred from the aminostratigraphy and aminochronology of Quaternary dunes and palaeosols from the eastern islands of the Canary Archipelago. J. Quat. Sci. 21: 287–306.

Peel, M. C., Finlayson, B. L. & Mcmahon, T. A. (2007). Updated world map of the KÖPPEN- GEIGER climate classification, Hydrol. Earth Syst. Sci., 11, 1633-1644, https://doi.org/10.5194/hess-11-1633-2007, 2007.

Petit-Maire, N., Delibrias, G., Meco, J., Pomel, S. & Rosso, J., C. (1986). Paléoclimatologie des Canaries orientales (Fuerteventura). C. R. Acad. Sci. 303 (13): 1241–1246 (Série II).

Rodríguez, A. R., Mora, J. L., Arbelo, C. & Bordon, J. (2005). Plant succession and soil degradation in desertified areas (Fuerteventura, Canary Islands, Spain). Catena 59(2): 117- 131.

Roettig, C. B., Kolb, T., Wolf, D., Baumgart, P., Richter, C., Schleicher, A., Zöller, L. & Faust, D. (2017). Complexity of Quaternary aeolian dynamics (Canary Islands). Palaeogeography, Palaeoclimatology, Palaeoecology, 472: 146-162.

Roettig, C. B., Varga, G., Sauer, D., Kolb, T., Wolf, D., Makowsky, V., Espejoe , J. M. R., Zöller, L. & Faust, D. (2018). Characteristics, nature and formation of palaeosurfaces within dunes on Fuerteventura. Quaternary Research (2018), 1-20.

Rognon, P., Coudé-Gaussen, G., Le Coustumer, M. N., Balouet, J. C. & Occhietti, S. (1989). Le massif dunaire de Jandía (Fuerteventura, Canaries): Évolution des paléoenvironnements de 20.000 BP à l'actuel. Bull. Assoc. Fr. Etude Quat. 1989 (1): 31–37.

Roskin, J., Katra, I., Porat, N. & Zilberman, E. (2013). Evolution of Middle to Late Pleistocene sandy calcareous paleosols underlying the northwestern Negev Desert Dunefield (Israel). Palaeogeogr. Palaeoclimatol. Palaeoecol. 387: 134–152.

Rothe, P. (2008). Kanarische Inseln. Sammlung Geologischer Führer. Gebrüder Bornträger, Berlin, Stuttgart, pp. 338.

Rousseau D.-D., Puisségur J.-J. & Lautridou J.-P. (1990). Biogeography of the Pleistocene pleniglacial malacofaunas in Europe - Stratigraphic and climatic implications. Palaeogeography, Palaeoclimatology, Palaeoecology, 80: 7-23.

Ruiz Ruiz, A., Cárcaba Pozo, A., Porras Cre-Villen, A. I. & Arrébola, J. R. (2006). Guía de los caracoles terrestres de Andalucía. Fundación Gypaetus, Seville.

Serna, J. T. & Gomez, J. T. (2008). Contribución al conocimiento de los moluscos fósiles de las Islas Canarias. Associació Catalana de Malacologia, SPIRA 2 (4): 199-221.

Shannon, C.E. (1948) A mathematical theory of communication. Bell System Technical Journal

27: 379-423.

Suchodoletz, H.v., Kühn, P., Hambach, U., Dietze, M., Zöller, L. & Faust, D. (2009). Loess-like and palaeosol sediments from Lanzarote (Canary Islands/Spain) - indicators of palaeoenvironmental change during the Late Quaternary. Palaeogeogr. Palaeoclimatol. Palaeoecol 278: 71–87.

Suchodoletz, H., Oberhänsli, H., Hambach, U., Zöller, L., Fuchs, M., & Faust, D. (2010). Soil moisture fluctuations recorded in Saharan dust deposits on Lanzarote (Canary Islands) over the last 180ka. Quaternary Science Reviews 29(17): 2173-2184.

Welter-Schultes, F. W. (2012): European non-marine molluscs, a guide for species identification. Planet Poster Editions, Göttingen. 674 + Q1-78 pp.

Wenzel, F. (2017). Geologische Erkundungen auf Fuerteventura, 4. Teil: Fossile Landschnecken südlich von Corralejo. Downloaded on 02 March 2018 https://www.steinkern.de/fundorte/sonstige-laender/1198-fuerteventura-teil-4.html

Yanes, Y., Castillo, C., Hutterer, R., De La Nuez, J., Quesada, M., Torres, T., Ortiz, J. E., Alonso, M. R. & Ibáñez, M. (2004). Valoración patrimonial de las formaciones dunares cuaternarias del Barranco de los Encantados y Cantera de Melián de la isla de Fuerteventura (Islas Canarias). Geogaceta (36): 195-198.

Yanes, Y., Yapp, C. J., Ibáñez, M., Alonso, M. R., De-La-Nuez, J., Quesada, M. L., Castillo, C. & Delgado, A. (2011). Pleistocene–Holocene environmental change in the Canary Archipelago as inferred from the stable isotope composition of land snail shells. Quaternary Research 75(3): 658-669.

Yanes, Y., García-Alix, A., Asta, M. P., Ibáñez, M., Alonso, M. R. & Delgado, A. (2013). Late Pleistocene–Holocene environmental conditions in Lanzarote (Canary Islands) inferred from calcitic and aragonitic land snail shells and bird bones. Palaeogeography, Palaeoclimatology, Palaeoecology 378: 91-102.

2.9 SUPPLEMENTARY MATERIAL

Tab. 2.2 Detailed mollusc record for Encantado.

Lithological unit E-L2 E-L2 E-L2 E-L4 E-L5 E-L6 E-L7 E-L7 E-L8 E-L8 E-L9 E-L9 E-L10 E-L12 E-L12 E-L13 E-L13 E-L14 E-L14 E-L14 E-L16 E-L17 E-L18 E-L20 E-L21 E-L22 Sample number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 23 24 25 26 27 Entire ind. ------2 - - - 4 ------Canariella Fragments 6 ------2 8 - - 10 ------4 - - - - plutonia Total 2 ------4 6 - - 10 ------4 - - - - Entire ind. ------4 - - - Candidula Fragments ------2 6 - 8 8 4 - - - ultima n. ssp. Total ------2 6 - 6 8 8 - - - Entire ind. ------2 ------Caracollina Fragments ------lenticula Total ------2 ------Entire ind. ------Cochlicella n. sp. Fragments - - 4 6 - 20 36 672 620 8 ------2 - Total - - 4 6 - 20 36 672 620 8 ------2 - Entire ind. - - 2 6 2 - - 62 - - - 14 1 ------Cryptella Fragments 14 4 2 - - 6 4 24 2 8 - 10 1 ------2 - auriculata Total 10 2 4 6 2 6 4 86 2 6 - 22 2 ------2 - Entire ind. ------Ferussacia Fragments ------10 2 4 2 ------2 - - - - - valida Total ------10 2 4 2 ------2 - - - - - Entire ind. ------Ferussacia n. sp. Fragments ------4 2 - 2 ------Total ------4 2 - 2 ------Entire ind. ------2 ------2 ------Hemicycla cf. Fragments ------10 - 48 ------2 ------paeteliana Total ------10 - 16 ------4 ------Entire ind. ------Hemicycla n. sp. Fragments ------2 ------Total ------2 ------Entire ind. ------Hemicycla spp. Fragments ------6 - - 14 ------14 - - 2 - 1 - 6 indet. Total ------2 - - 4 ------6 - - 2 - 1 - 2 Entire ind. ------4 - - - Granopupa Fragments ------granum Total ------4 - - - Entire ind. - 2 2 6 2 4 - 40 - 10 7 - 8 12 - - 20 6 6 4 6 6 24 - 2 14 Monilearia Fragments 2 14 2 2 2 10 2 56 - 18 10 - 8 8 - - 30 2 8 2 12 36 28 1 16 8 monilifera Total 2 16 4 8 4 14 2 96 - 28 17 - 16 20 - - 50 8 14 6 18 42 52 1 18 22 Entire ind. ------2 ------Obelus cf. disco- Fragments ------2 ------granulatus Total ------2 ------2 ------Entire ind. - - - 60 76 ------Obelus pumilio Fragments - - 20 80 172 94 20 ------Total - - 20 140 248 94 20 ------Entire ind. ------14 ------4 ------Pomatias aff. Fragments ------2 - - 56 ------6 - 2 2 - - - - lanzarotensis Total ------2 - - 70 ------10 - 2 2 - - - - Entire ind. ------Rumina Fragments ------2 - 12 12 decollata Total ------2 - 6 8 Entire ind. 74 276 196 144 288 110 152 218 6 400 5 100 81 300 237 2 108 128 76 40 44 28 56 15 10 56 Theba spp. Broken ind. 200 422 324 266 174 222 244 362 200 516 49 64 158 442 549 40 152 84 58 30 50 130 184 4 14 56 indet. Clean shells 56 - - 12 40 48 - 46 6 190 2 12 17 68 3 2 2 32 26 34 12 22 48 7 10 26 Total 274 698 520 410 462 332 396 580 206 916 54 164 239 742 786 42 260 212 134 70 94 158 240 19 24 112 Entire ind. ------2 - - 2 ------2 - - - Xerotricha Fragments 4 ------12 - 4 ------10 - - - lancerottensis Total 4 - - - - - 2 12 - 22 ------12 - - - Snail eggs Fragments ------(Rumina) Total ------4 8 sp.Monilearia/X Fragments ------10 ------erotricha Total ------10 ------

split 1 time for analysis⁽¹⁾ split 2 times for analysis⁽¹⁾ split 3 times for analysis⁽¹⁾

⁽¹⁾ all countings were extrapolated ….to the original sample size 47

Tab. 2.3 Detailed mollusc record for Melián.

Lithological unit M-L1 M-L2 M-L3 M-L4 M-L5 M-L5 M-L6 M-L6 M-L6 M-L6 M-L7 M-L8 M-L8 M-L8 M-L9 M-L9 M-L10 M-L11 M-L11 M-L11 M-L11 M-L12 M-L12 M-L12 M-L12 M-L12 M-L14

Sample number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 24 25 26 27 28 Entire ind. ------2 ------Canariella Fragments - - - - - 2 - - - - 2 ------plutonia Total - - - - - 2 2 - - - 2 ------Entire ind. - - - - - 14 - 2 14 4 - 1 ------Candidula Fragments ------10 24 8 4 - 2 ------ultima n. ssp. Total - - - - - 14 10 26 22 8 - 3 ------Entire ind. ------8 ------Caracollina Fragments - - - - 4 4 - 6 - - - - - 32 ------2 - lenticula Total - - - - 4 4 - 6 - - - - - 40 ------2 - Entire ind. - - - - - 36 - - 2 ------Cochlicella n. Fragments - - - 18 168 1298 18 178 254 30 10 ------sp. Total - - - 16 148 1180 8 134 108 22 4 ------Entire ind. - - - 2 - 18 2 - 2 2 ------Cryptella Fragments 4 4 2 - 10 24 2 20 2 6 ------1 auriculata Total 4 2 2 2 8 40 4 14 4 8 ------1 Entire ind. ------Ferussacia Fragments - - - - - 8 - - - - - 2 ------valida Total - - - - - 8 - - - - - 2 ------Entire ind. ------Ferussacia n. sp. Fragments - - - - - 4 ------Total - - - - - 4 ------Entire ind. ------Hemicycla cf. Fragments - - - - 2 - 2 ------Paeteliana Total - - - - 2 - 2 ------Entire ind. ------Hemicycla spp. Fragments - - - - - 6 - - 2 6 4 2 - 8 ------1 - - - indet. Total - - - - - 4 - - 2 2 4 2 - 8 ------1 - - - Entire ind. - - - - - 4 ------16 ------Granopupa Fragments ------1 - 16 ------granum Total - - - - - 4 - - - - - 1 - 24 ------Entire ind. 12 - 4 - 30 50 2 - 8 2 2 49 18 208 212 - 30 18 8 2 - 8 22 - 4 - 9 Monilearia Fragments 26 2 6 12 64 118 22 30 2 - 6 275 26 696 560 44 124 82 42 52 - 11 84 - 17 11 58 monilifera Total 38 2 10 12 94 168 24 30 10 2 8 324 44 744 772 44 154 100 50 54 - 29 106 - 21 11 67 Entire ind. ------Obelus pumilio Fragments - - - 40 - 2 - 2 ------Total - - - 32 - 2 - 2 ------Entire ind. ------2 1 ------Pomatias aff. Fragments ------2 28 6 ------lanzarotensis Total ------2 30 7 ------Entire ind. ------8 ------Rumina Fragments ------3 - 192 - 3 6 2 - 2 - 2 4 - 1 4 17 decollata Total ------3 - 144 - 3 6 2 - 2 - 2 4 - 1 2 15 Entire ind. ------Rumina saharica Fragments ------4 - 2 ------Total ------4 - 2 ------Entire ind. 104 24 68 726 518 698 414 236 164 86 74 206 237 1408 792 1 132 152 244 90 283 44 82 - 36 2 56 Theba spp. Broken ind. 202 58 90 634 628 1656 378 618 132 64 100 763 168 4016 2516 414 804 812 438 694 702 285 638 109 219 201 154 indet. Clean shells 56 8 0 8 44 58 252 134 8 6 30 206 0 1144 608 0 132 10 230 86 249 44 82 alle 36 2 12 Total 306 82 158 1360 1146 2354 792 854 296 150 174 969 405 5424 3308 415 936 964 682 784 985 329 720 109 255 203 210 Entire ind. 2 - - 2 38 226 6 30 - - - 7 - 24 32 - - - - - 19 11 2 - 6 - - Xerotricha Fragments 2 2 - 10 26 490 28 50 - - - 3 - 264 124 - - - - - 57 21 8 - 11 - - lancerottensis Total 4 2 - 12 64 716 34 80 - - - 10 - 288 156 - - - - - 76 32 10 - 17 - - Snail eggs Fragments ------(Rumina) Total ------2 1 176 ------1 - 2 sp.Monilearia/ Fragments ------8 - - - Xerotricha Total ------8 - - -

Tab. 2.4 Detailed mollusc record for Jable.

n. sp. n.

indet. indet.

valida

plutonia

Cryptella

Canariella Candidula auriculata

Hemicycla Hemicycla monilifera

Ferussacia Xerotricha

Monilearia

Theba spp. Theba

Pomatias aff.

lanzarotensis

ultimassp.n.

lancerottensis

Hemicyclaspp.

Lithologicalunit

Sample number Sample

Total Total Total Total Total Total Total Total Total Total

Fragments Fragments Fragments Fragments Fragments Fragments Fragments Fragments Fragments

Entire ind. Entire ind. Entire ind. Entire ind. Entire ind. Entire ind. Entire ind. Entire ind. Entire ind. Entire ind.

Broken ind.Broken

Clean shells

------

2 2 2 6 6 2 2 2 2 3 4 4 8 0

10 10 18 12 52 64

206 160 366

HW-L2

------

1 2 2 8 2 6 6 8 8 2 2 4

10 26 30 56 16 16

344 278 622 HW-L4

Tab. 2.5 Community ecological and taphonomic indices from gastropod analysis for Encantado.

Sample Shannon Species Total Breakage Coating biodiversity richness abundance rate rate index E3-27 0,70 4 144 0,50 0,54 E3-26 1,22 5 52 0,58 0,00 E3-25 0,38 3 21 0,21 0,53 E3-24 0,81 6 318 0,77 0,14 E3-23 0,83 6 216 0,82 0,21 E3-21Sample 0,77Shannon 5Species 122Total 0,53Breakage 0,73Coating E3-20 0,56biodiversity 4richness 82abundance 0,43rate 0,15rate E3-19 0,80index 5 170 0,43 0,66 E3-18E3-27 0,210,70 34 222144 0,400,50 0,750,54 E3-17E3-26 0,441,22 25 31052 0,580,58 0,980,00 E3-16E3-25 0,180,38 23 4421 0,950,21 0,000,53 E3-15E3-24 0,000,81 16 786318 0,700,77 0,990,14 E3-14E3-23 0,120,83 26 762216 0,600,82 0,770,21 E3-13E3-21 0,280,77 35 257122 0,660,53 0,790,73 E3-12E3-20 1,040,56 54 27082 0,390,43 0,880,15 E3-11E3-19 0,660,80 35 73170 0,910,43 0,600,66 E3-10E3-18 0,430,21 73 1002222 0,560,40 0,530,75 E3-9E3-17 0,730,44 82 852310 0,970,58 0,000,98 E3-8E3-16 1,210,18 92 147444 0,620,95 0,790,00 E3-7E3-15 0,580,00 71 462786 0,620,70 1,000,99 E3-6E3-14 0,860,12 52 466762 0,670,60 0,560,77 E3-5E3-13 0,700,28 43 716257 0,380,66 0,860,79 E3-4E3-12 0,741,04 55 570270 0,650,39 0,920,88 E3-3E3-11 0,280,66 53 55273 0,620,91 1,000,60 E3-2E3-10 0,130,43 37 7161002 0,600,56 1,000,53 E3-1E3-9 0,300,73 58 292852 0,730,97 0,240,00 E3-8 1,21 9 1474 0,62 0,79 Sample E3-7 Shannon0,58 Species7 Total462 Breakage0,62 Coating1,00 E3-6 biodiversity0,86 richness5 abundance466 rate0,67 rate0,56 E3-5 index0,70 4 716 0,38 0,86 E3-4 0,74 5 570 0,65 0,92 M-28 0,75 4 293 0,73 0,79 E3-3 0,28 5 552 0,62 1,00 M-27Tab. 2.0,306 Community4 ecological218 and0,99 taphonomic0,00 E3-2 0,13 3 716 0,60 1,00 M-26 0,50 4 294 0,86 0,00 indicesE3-1 0,30from gastropod5 analysis292 for0,73 Melián. 0,24 M-25 0,30 3 118 1,00 0,00 M-24 0,47 4 840 0,89 0,00 Sample Shannon Species Total Breakage Coating M-23 0,57 4 392 0,87 0,00 biodiversity richness abundance rate rate M-22 0,26 2 1061 0,71 0,12 index M-21 0,26 3 840 0,89 0,04 M-20M-28 0,250,75 24 732293 0,640,73 0,060,79 M-19M-27 0,320,30 34 1066218 0,840,99 0,930,00 M-18M-26 0,450,50 34 1098294 0,860,86 0,000,00 M-17M-25 0,350,30 33 462118 1,001,00 1,000,00 M-16M-24 0,630,47 44 4240840 0,760,89 0,230,00 M-14M-23 0,690,57 74 6672392 0,740,87 0,190,00 M-13M-22 0,320,26 22 4491061 0,410,71 1,000,12 M-12M-21 0,690,26 93 1321840 0,810,89 0,000,04 M-11M-20 0,740,25 62 220732 0,570,64 0,590,06 M-10M-19 0,850,32 73 1941066 0,430,84 0,930,93 M-9M-18 0,910,45 63 4421098 0,450,86 0,950,00 M-8M-17 0,930,35 83 1146462 0,721,00 0,431,00 M-7M-16 0,460,63 84 8764240 0,480,76 0,390,23 M-6M-14 1,210,69 127 45006672 0,700,74 0,920,19 M-5M-13 0,790,32 72 1466449 0,550,41 0,921,00 M-4M-12 0,270,69 69 14341321 0,470,81 0,990,00 M-3M-11 0,290,74 36 170220 0,570,57 1,000,59 M-2M-10 0,320,85 47 88194 0,710,43 0,670,93 M-1M-9 0,460,91 46 352442 0,660,45 0,460,95 M-8 0,93 8 1146 0,72 0,43 SampleM-7 Shannon0,46 Species8 Total876 Breakage0,48 Coating0,39 M-6 biodiversity1,21 richness12 abundance4500 rate0,70 rate0,92 M-5 index0,79 7 1466 0,55 0,92 HW-1M-4 0,560,27 76 7181434 0,450,47 0,980,99 HW-2M-3 0,800,29 73 470170 0,440,57 1,001,00 M-2 0,32 4 88 0,71 0,67 M-1 0,46 4 352 0,66 0,46

Sample Shannon Species Total Breakage Coating biodiversity richness abundance rate rate index HW-1 0,56 7 718 0,45 0,98 HW-2 0,80 7 470 0,44 1,00

Sample Shannon Species Total Breakage Coating biodiversity richness abundance rate rate index E3-27 0,70 4 144 0,50 0,54 E3-26 1,22 5 52 0,58 0,00 E3-25 0,38 3 21 0,21 0,53 E3-24 0,81 6 318 0,77 0,14 E3-23 0,83 6 216 0,82 0,21 E3-21 0,77 5 122 0,53 0,73 E3-20 0,56 4 82 0,43 0,15 E3-19 0,80 5 170 0,43 0,66 E3-18 0,21 3 222 0,40 0,75 E3-17 0,44 2 310 0,58 0,98 E3-16 0,18 2 44 0,95 0,00 E3-15 0,00 1 786 0,70 0,99 E3-14 0,12 2 762 0,60 0,77 E3-13 0,28 3 257 0,66 0,79 E3-12 1,04 5 270 0,39 0,88 E3-11 0,66 3 73 0,91 0,60 E3-10 0,43 7 1002 0,56 0,53 E3-9 0,73 8 852 0,97 0,00 E3-8 1,21 9 1474 0,62 0,79 E3-7 0,58 7 462 0,62 1,00 E3-6 0,86 5 466 0,67 0,56 E3-5 0,70 4 716 0,38 0,86 E3-4 0,74 5 570 0,65 0,92 E3-3 0,28 5 552 0,62 1,00 E3-2 0,13 3 716 0,60 1,00 E3-1 0,30 5 292 0,73 0,24

Sample Shannon Species Total Breakage Coating biodiversity richness abundance rate rate index M-28 0,75 4 293 0,73 0,79 M-27 0,30 4 218 0,99 0,00 M-26 0,50 4 294 0,86 0,00 M-25 0,30 3 118 1,00 0,00 M-24 0,47 4 840 0,89 0,00 M-23 0,57 4 392 0,87 0,00 M-22 0,26 2 1061 0,71 0,12 M-21 0,26 3 840 0,89 0,04 M-20 0,25 2 732 0,64 0,06 M-19 0,32 3 1066 0,84 0,93 M-18 0,45 3 1098 0,86 0,00 M-17 0,35 3 462 1,00 1,00 M-16 0,63 4 4240 0,76 0,23 M-14 0,69 7 6672 0,74 0,19 M-13 0,32 2 449 0,41 1,00 M-12 0,69 9 1321 0,81 0,00 M-11 0,74 6 220 0,57 0,59 M-10 0,85 7 194 0,43 0,93 M-9 0,91 6 442 0,45 0,95 M-8 0,93 8 1146 0,72 0,43 M-7 0,46 8 876 0,48 0,39 M-6 1,21 12 4500 0,70 0,92 M-5 0,79 7 1466 0,55 0,92 M-4 0,27 6 1434 0,47 0,99 Tab.M-3 2.70,29 Community3 ecological170 and0,57 taphonomic1,00 M-2 0,32 4 88 0,71 0,67 indicesM-1 from0,46 gastropod4 analysis352 for 0,66Jable. 0,46

Sample Shannon Species Total Breakage Coating biodiversity richness abundance rate rate index HW-1 0,56 7 718 0,45 0,98 HW-2 0,80 7 470 0,44 1,00

Tab. 2.8 Record of selective species surveys from fossil deposits in the study area (incomplete)

La Costilla pit Melian pit

Koordinaten: Koordinaten: 28° 41‘ 22,2‘‘ N – 28° 40‘ 20,6‘‘ N – 13° 58‘ 15,0‘‘ W, 13° 57‘ 10,0‘‘ W, 81 m NN 90 m NN Canariella plutonia x x Candidula ultima n. ssp. x x Cochlicella n. sp. x x Cryptella auriculata x - Ferussacia n. sp. - x Hemicycla gravida x - Hemicycla n. sp. x x Hemicycla cf. paeteliana x x Hemicycla sarcostoma x x Hemicycla aff. sarcostoma - x Monilearia monilifera x x Pomatias aff. lanzarotensis x x Rumina decollata x x Rumina saharica x x Theba cf. arinagae x x Theba costillae x - Theba geminata x x Theba n. sp. 1 (globulous, bloated shape) - x Theba n. sp. 2 (only juveniles, wide umbilicus, upper part of the shell flat) x x Xerotricha lancerottensis - x from Hutterer (1990): - - Napaeus sp. (cf. lichenicola ) x - Ferussacia sp. (cf. valida ) x -

3 QUATERNARY GASTROPOD FAUNAS IN SOUTHERN CAUCASIA AND INDICATIONS ON ENVIRONMENTAL CHANGES

Chapter 3 is published in the peer-reviewed Journal of Quaternary Sciences as:

NEW INSIGHTS INTO SOUTHERN CAUCASIAN GLACIAL-INTERGLACIAL CLIMATE CONDITIONS INFERRED FROM QUATERNARY GASTROPOD FAUNAS

Authors: Christiane Richter1, Daniel Wolf1, Frank Walther², Stefan Meng³, Lilit Sahakyan4, Hayk Hovakimyan4, Tilmann Wolpert5, Markus Fuchs5, Dominik Faust1

1Dresden University of Technology, Helmholtzstraße 10, 01069 Dresden 2 University Hamburg, Martin-Luther-Platz 3, 20146 Hamburg 3 Ernst-Moritz-Arndt-University Greifswald, Friedrich-Ludwig-Jahn-Str. 17a, 17489 Greifswald 4 National Academy of Sciences of the Republic of Armenia, Baghramyan Ave. 24a, 0019 Yerevan 5 Justus-Liebig-University Giessen, Senckenbergstr. 1, 35390 Gießen

Publication history: submitted: September 2019, accepted: April 2020

Full reference: Richter, C., Wolf, D., Walther, F., Meng, S., Sahakyan, L., Hovakimyan, H., Wolper, T., Fuchs, M. & D. Faust (2020). New insights into Southern Caucasian glacial-interglacial climate conditions inferred from Quaternary gastropod fauna. Journal of Quaternary Science, 35(5), 634-649.

Abstract. In the present study, we performed gastropod analyses on loess palaeosol sequences from northeast Armenia (Southern Caucasia) covering at least three glacial- interglacial cycles. The elaborated ecostratigraphy shows significant patterns of species composition related to the succession of pedocomplexes and loess, respectively. Pedocomplexes included species that can be associated with highgrass- to forest-steppe biomes, indicating increased humidity for these sections compared to loess layers. In contrast, loess layers that relate to glacial periods are associated with gastropod species of semidesert environments with shrub- and shortgrass-steppes, indicating semiarid to arid conditions. Furthermore, the loess deposits do not show any evidence for cold-adapted gastropod species. Therefore, we suggest that average July temperatures in the study area were above 10°C, even during periods of loess deposition. Consequently, we propose that the limiting factor for tree growth during glacial periods was aridity, rather than temperature. In addition, we observe environmental differences between the various glacial times, with our results indicating a trend towards steadily increasing aridity in Southern Caucasia across the Middle to Late Pleistocene.

3.1 INTRODUCTION

Loess deposits are important archives for the reconstruction of Quaternary environmental and climatic conditions. As a multitude of marine and terrestrial archives show, the Quaternary climate was characterised by strong fluctuations. Within loess deposits, these fluctuations led to the development of loess palaeosol sequences (Pecsi & Richter, 1996, Antoine et al., 2009, Meszner et al., 2011, Marković et al., 2015, Vlaminck et al., 2018, Schaetzl et al., 2018). There have been extensive studies on loess in recent decades, but global climate relations and their impact on local environmental conditions, especially on terrestrial ecosystems, leave fundamental questions unanswered (Zeeden et al., 2018, Obreht et al., 2019). Recently, Wolf et al. (2016) described and investigated loess deposits in the Southern Caucasian region, thus closing a spatial gap in global loess research (comp. e.g., Jefferson et al., 2003, Muhs and Bettis, 2003, Wolf et al., 2016). These loess deposits from the north-eastern foreland of the Lesser Caucasus provide excellent archives to investigate the causal network between climatic conditions, sediment supply and soil formation processes. Pedogenesis for Middle to Late Pleistocene deposits in Western and Central Asia is usually associated with higher palaeotemperatures and elevated humidity (Dodonov & Baiguzina, 1995, Joannin et al., 2010), which is consistent with the Central European loess belt. Palynological studies provided detailed information on environmental conditions and palaeovegetation in the wider study region. For the interglacial phases, there are indications of extensive occurrences of forests to forest-steppes for areas north of the Greater Caucasus (Bolikhovskaya et al., 2006) and at Lake Van (Litt et al., 2014, Kwiecien et al., 2014, Pickarski & Litt, 2017). However, since pollen can be transported over long distances and therefore, also may be biased by fractionation, the information about palaeovegetation in glacial times is still uncertain. In addition, recent n- alkane studies conducted on loess palaeosol sequences (LPS) in NE-Armenia show ambivalent results with regard to sedimentological proxies and bioproxy signals (Trigui et al., 2019). Therefore, it is important to investigate several biological markers in order to compare environmental information and to approach a reliable reconstruction of palaeoecological conditions. Due to their frequent occurrence and good conservation in Pleistocene deposits, the analysis of (sub)fossil gastropods is a central part of Quaternary science (e.g. Ložek, 1990, Moine et al., 2005, 2008, Penkman et al., 2011, Limondin-Lozouet & Preece, 2014, Juřičková et al., 2014, Rousseau et al., 2018, Horsák et al., 2019). Gastropods are very sensitive to environmental changes and are therefore particularly suitable for displaying palaeoecological conditions. However, research on palaeo-records for the study area has been very sparse so far. For Armenia, there were extensive investigations by Steklov (1966) on Neogene mollusc occurrences, but detailed studies on Quaternary terrestrial gastropods in the Caucasus region are still pending. As ecosystems in this study area are unique and characterised by high

52 endemism, our results will serve as an important bridge to establish the connection to gastropod records in neighbouring loess regions, such as the Carpathian Basin (e.g. Alexandrowicz et al., 2002, Stoica et al., 2007, Alexandrowicz et al., 2014, Sümegi et al., 2018, Obreht et al., 2019), or Eastern Siberia (Danukalova et al., 2007, Osipova & Danukalova, 2011, Danukalova et al., 2015). The central questions of this study are on the one hand, whether it is possible to distinguish different biozones within the deposits. On the other hand, we wanted to find out to what extent environmental and climate conditions can be derived from gastropod communities and biozones respectively. Based on extensive gastropod studies, which were strongly focused on the succession of stratigraphic units according to Wolf et al. (2016), our results provide new insights into Pleistocene conditions associated with at least three glacial- interglacial cycles.

3.2 STUDY AREA

The study area is situated at the north-eastern foothills of the Lesser Caucasus close to the Armenian village of Sevkar (Fig. 3.1). The investigated outcrops, section Sevkar (680 m. a.s.l., 41°00’23’’ N, 45°10’22’’ E) and section BL (680 m. a.s.l., 41°01’32.9’’ N, 45°10’00.7’’ E), are

Fig. 3.1 Topographic map of the study region, with the red rectangle marking the study area (modified from maps-for-free.com).

53 located in the catchment of the river Aghstev. This river drains into the Azerbaijani Kura Basin, which is part of the tectonic depression between the Lesser Caucasus and the Greater Caucasus. The bedrock below the Quaternary deposits within the study area mainly consists of Mesozoic sediments and volcanic rocks. Today, the study area is characterised by a humid, temperate climate with hot summers and an average annual precipitation of 507 mm, with maxima of 85 mm in May and minima of 20 mm in December and January. The mean annual temperature is 11.1°C, with a highest monthly average of 22.3°C in summer and lowest -0.1°C in winter.

Since the Pleistocene, the Caucasus mountain chain climatically separated Southern Caucasia from cold winds from the north. The tectonic depression between Greater and Lesser Caucasus was thus a protected retreat during glacial periods, whereby hygrothermophilic tertiary relict flora is still preserved in the large-scale refuges of the Hyrkan and Colchic lowland areas (Zazanashvili et al. 2000, Zazanashvili et al., 2004). According to Gobejishvili (2004), the low altitude and high drought of the Lesser Caucasus limited the maximum ice advance for the last glaciation to 1700 m above sea level. Today, the mountain ridge of the Likhi range (Fig. 3.1) separates the study area from humid air masses from the Black Sea (Lydolph, 1977), leading to higher aridity in the Kura basin.

3.3 METHODS

3.3.1 Fieldwork

Based on detailed lithostratigraphic and geochemical investigations by Wolf et al. (2016), the two sections Sevkar and BL (comp. Wolf et al., 2016) were selected for the mollusc analyses in order to have as complete and undisturbed sequences as possible. Mollusc samples were taken with a volume of 10 l sediment each, with the sample positions selected according to lithological units as shown in Figs. 3.2 & 3.3. We collected 81 samples from the BL site over a height of 28 metres and 18 samples from the Sevkar site over a height of 10 metres. A detailed stratigraphic description of the Sevkar and BL sections is published in Wolf et al. (2016). A brief description of the lithofaciestypes (see Figs. 3.2 and 3.3) is given in Tab. 3.1.

3.3.2 Laboratory analyses

Extraction of gastropod shells

All samples were wet sieved to the fraction > 500 µm to extract the shells. Since the sediment was highly aggregated by clay contents of up to 60%, the samples had to be additionally prepared with a laboratory shaker for 3 to 10 hours before sieving, depending on the material.

Heavily soiled shells were cleaned with an ultrasonic bath. Extracted shells were determined and quantified using a stereomicroscope with 20 to 40-fold magnification. Pictures were processed with an Axiocam ICc1 microscope camera with z-stack capable software. Complete shells and diagnostic shell fragments were counted and offset against each other as described e.g. in Ložek (1990) and Richter et al. (2019).

Optically stimulated luminescence dating

First luminescence age estimates were performed for the section of BL, using the polymineral fine grain fraction (4 – 11 µm). To minimize age underestimation as a result of anomalous fading, a modified post-IR IRSL225 protocol was applied (Buylaert et al., 2009) and no fading correction procedure was performed. Therefore, the two luminescence ages represent preliminary minimum age estimates and should be interpreted with caution. Further experimental details are given in the supplementary material (Tab. 3.3).

Tab. 3.1 Description of lithofacies types in sections Sevkar and BL.

Lithofacies types Abbreviation Description . Interpretation

S dark-brown to blackish coloured loam to clay with clay palaeosol contents predominantly between 35 and 58% and 0,2 to 1,2% organic matter (Corg), partly containing reworked clay pepples as well as insitu pedogenic features such as crumbly to prismatic aggregates, pedogenetic carbonate enrichments (calcareous pseudomycelia), bioturbation, root channels and numerous krotovinas

WS weakly weathered, brownish coloured loamy silt to loam, weak palaeosol insitu pedogenesis is indicated by gradually increasing loam formation content to the top

L silt, containing carbonate and volcanic glasses loess

V light bluish coloured material, predominantly volcanic glass tephra

C loam with incorporated dark rounded clay pepples relocated colluvial material

F homogenous clayey loam with sharp boundaries to the strongly weathered adjacent layers loess

3.3.3 Generation of malacozones

The subdivision of the sections into malacozones was based on both, absolute occurrences and abundances of certain taxa. The defined malacozones are presumed to correspond to ecostratigraphic zones and are named after the dominant members of the respective assemblages.

3.3.4 Statistical analyses

Cluster analysis

To determine the similarity between assemblages, a cluster analysis based on the Morisita similarity index (Morisita, 1959) was applied. Therefore, we considered both, qualitative presence-absence data and quantitative abundance data. The index was calculated for all sample pairs using the palaeontological statistics software PAST (published by Hammer, Harper & Ryan, 2001), and varies from 0 (no similarity) to 1 (full similarity). The results are presented as a dendrogram in which the most similar samples are combined into clusters.

Test of significance

We used the t-test as significance test. The statistical test procedure was used to quantify the relevance (significance) of gastropod species dependencies on environmental parameters (magnetic susceptibility, organic carbon content, granulometric data, carbonate content, conductivity) extracted from Wolf et al. (2016). The modelling of the regression model and the determination of the relevant variables was performed using the palaeontological statistics software PAST (published by Hammer, Harper & Ryan, 2001). In Tab. 3.4, significantly related pairs (level of significance p < 0.05) were marked with asterisks (*** strong correlation, ** moderate correlation, * weak correlation).

3.4 RESULTS

3.4.1 Composition of investigated gastropod assemblages

The gastropod fauna of the investigated profile sites BL and Sevkar comprises at least 20 terrestrial species. In total, (sub)fossil shells and shell fragments of 10296 individuals were found, belonging to the following taxa: Aegopinella indet. (Lindholm, 1927), Cecilioides acicula (Müller, 1774), Chondrula tridens (Müller, 1774), Gibbulinopsis interrupta (Reinhardt in Martens, 1876), Gibbulinopsis signata (Mousson, 1873), Imparietula indet. (Lindholm, 1925),

Fig. 3.2 Mollusc diagram illustrating the species composition and abundances for gastropods of the BL section. The legend can be taken from the legend in Fig. 3.3. Malacozones are depicted according to Chap. 3.4.2. (on the right). Coloured brackets at the top show the allocation of each taxon to ecological categorisations (comp. Chap. 3.5.1); the arrow bar visualises the implication on the associated moisture regime (comp. Chap. 3.5.2).

We refer to the digital version for coloured figures. 57

Fig. 3.3 Mollusc diagram illustrating the species composition and abundances for gastropods of the Sevkar section. Malacozones are depicted according to Chap. 3.4.2. (on the right). Coloured brackets at the top show the allocation of each taxon to ecological categorisations (comp. Chap. 3.5.1); the arrow bar visualises the implication on the associated moisture regime (comp. Chap. 3.5.2). We refer to the digital version for coloured figures. Mollusc diagram illustrating the species composition and abundances for gastropods of the Sevkar section. Malacozones are depicted according to Chap. 3.4.2. (on the right). Coloured brackets at the top show the allocation of each taxon to ecological categorisations (comp. Chap. 3.5.1); the arrow bar visualises the implication on the associated moisture regime (comp. Chap. 3.5.2). We refer to the digital version for coloured figures.

Fig. 3.4 Picture plate of the (sub)fossil gastropod species. 1- 2) Harmozica selecta(1) (a-apical view, b- apertural view, c- umbilical view), 3) Xeropicta derbentina(1), 4) Chondrula tridens(1), 5) Vallonia costata(2), 6) Vitrea pygmaea(2), 7) Inner plate of a slug, 8) Microtus arvalis (chewing surface of a molar tooth) , 9) Lucanus(2) indet. (mandible) , 10-12) Pupilla kyrostriata(3), 13-15) Pupilla aff. poltavica(3), 16) Truncatellina cylindrica(1), 17-18) Gibbulinopsis interrupta(3), 19-20) Pupilla inops(3), 21) Cecilioides acicula(2) – (1)from colluvial layers BL1 and BL2, (2) from Holocene layers BL4 and BL5, (3) from deposits of BL

Kalitinaia crenimargo (Pfeiffer, 1848), Multidentula pupoides (Krynicki, 1833), Pupilla bipapulata (Akramowski, 1943), Pupilla kyrostriata (Walther & Hausdorf, 2014), Pupilla inops (Reinhardt, 1877), Pupilla aff. poltavica (Boettger, 1889), Pupilla triplicata (Studer, 1820), Stenomphalia selecta (Klika, 1894), Truncatellina callicratis (Scacchi, 1833), Truncatellina cylindrica (Férussac, 1807), Vallonia costata (Müller, 1774), Vallonia pulchella (Müller, 1774), Vitrea pygmaea (Boettger, 1880), Xeropicta derbentina (Krynicki, 1836) (comp. Fig. 3.4). The composition and abundances of species are depicted in Figs. 3.2 and 3.3, while a detailed record is given in the supplementary material Tabs. A.3 and A.4. The depicted ecological information is discussed in Chapter 3.5.1.

3.4.2 Malacozonation

In order to detect significant changes in gastropod assemblages, we compared all samples of the same localities with respect to species composition, biodiversity, abundances and peak phases of certain taxa. In the following, eight different malacozones are defined and described. These correspond to an ecozonal biostratigraphy and usually reappear within the period investigated. Assemblages in colluvial layers must be treated with caution, as related taphocoenoses may contain both insitu and displaced shells. Likewise, the occurrence of C. acicula should be treated with caution, as this taxon is a subterranean species that can burrow 40 to 70 cm deep into the ground (e.g., Bonham, 2005). If one considers the expected shifts of the actual occurrence into overlying units, it seems that C. acicula occurs mainly at transitions from interglacial to glacial phases. Another possible scenario could be that the topsoils have been eroded and only the lower-lying subsoils are preserved. However, the shells of this species occur predominantly in connection with palaeosols, but within loess deposits, they hardly occur at all. Therefore, we assume that their presence is related to pedogenesis, or possibly to post-pedogenic transition phases towards drier conditions that provide enough organic matter as food source. Although C. acicula has not been used to define malacozones, significant occurrences of the species are similarly described below. The malacozones are composed as follows:

MZ A Truncatellina zone

Is characterised by the highest biodiversity for the period under study. The dominant species are ubiquitous species such as T. callicratis, S. selecta and T. cylindrica. This zone shows a parallel occurrence of elements of different ecological groups such as V. pygmaea and X. derbentina reprasentativ for forest ecosystems, V. pulchella (and C. acicula) as mesophilous steppe elements, and G. interrupta and K. crenimargo as xerophilous steppe to semidesert species. The corresponding assemblages also include M. pupoides, slug remains and C. tridens.

MZ B V. pygmaea zone

This zone is characterised by the presence of the mesophilous species V. pulchella and V. pygmaea, the latter living in humid steppes to forest biotopes. Respective assemblages furthermore include, C. tridens (, C. acicula) and partially forest steppe species such as X. derbentina and Aegopinella indet. This zone is characterised by a comparatively high biodiversity.

MZ C G. signata - V. pygmaea zone

Similar to malacozone B, but dominated by thermophilous elements such as G. signata (also high abundances of C. acicula). Respective assemblages furthermore include G. interrupta and V. costata.

MZ D K. crenimargo - G. interrupta zone

The malacofauna of this zone is limited to the occurrence of K. crenimargo and G. interrupta.

MZ D+ K. crenimargo - G. interrupta – P. aff. poltavica zone

This zone is characterised by a dominance of K. crenimargo and G. interrupta predominantly accompanied by P. aff. poltavica, with occasional presence of P. kyrostriata.

MZ E V. pulchella – C. tridens zone

This zone is characterised by the occurrence of the mesophilous species V. pulchella and the subterranean species C. acicula, which live in moist open ground to forest steppe biotopes, as well as the grassland species C. tridens. M. pupoides and G. signata sporadically appear. Respective assemblages furthermore include K. crenimargo, G. interrupta and occasionally P. aff. poltavica.

MZ F Hostile zone

Corresponding assemblages contain less than 5 individuals, suggesting hostile conditions

MZ F+ Unpreserved zone

Corresponding assemblages contain less than 5 individuals, but contain species which indicate favourable conditions, including demanding species such as V. pygmaea, V. pulchella and C. tridens.

MZ G M. pupoides – C. tridens zone

This zone is characterised by the presence of M. pupoides, K. crenimargo and C. tridens. Occasionally P. aff. poltavica appears. These species are supposed to live in shortgrass- steppes with scattered shrub vegetation. Vertebrate remains are common.

MZ G+ Abundant M. pupoides – C. tridens zone

Similar to malacozone G, but additionally including G. interrupta and sporadically V. pulchella. This zone furthermore differentiates from zone G by a generally higher biodiversity.

3.4.3 Cluster analysis

The dendrogram (Fig. 3.5) shows the results of the cluster analysis (see chapter 3.4.1). Typically associated species in terms of presence-absence data, frequencies and peak phases are clustered and probably shared common habitats. We used the results to compare which ecological requirements overlap for the clustered species in order to determine the smallest common tolerance range. From this tolerance range, the palaeoenvironments were derived as discussed in Chap. 3.5.1.

Fig. 3.5 Dendrogram showing typically associated gastropod species in the palaeo-record of the studied sections. Assumed ecological categorisations as discussed in Chap. 3.5.1 are marked with brackets.

3.4.4 Test of significance

In order to figure out dependencies between certain gastropod species and palaeoenvironmental parameters, we conducted a t-test. The results show a significant relationship between V. pygmaea and increased carbon content (p=0.00042027), as well as between M. pupoides and increased clay content (p=0.0038586). In addition, there is a moderate dependence for V. pulchella (p=0.027681), T. cylindrica (p=0.01176), X. derbentina (p=0,010833), G. signata (p=0.025623) and C. acicula (p=0.020867) on elevated organic

Fig. 3.6 Diagram showing clay contents and organic carbon contents for all gastropod samples. The ecological implications of the gastropod samples were identified in the sample name labelling and by different signatures as shown in the legend. Different soil colours are distinguished and labelled as shown in the legend. We refer to the digital version for coloured figures. carbon contents, and for G. signata (p=0.012271), C. acicula (p=0.021892) and Imparietula

63 sp. (p=0.029607) on electrical conductivity in the lithological units. A detailed regression table is given in the supplementary material Tab. 3.4.

Subsequently, we plotted all samples together with the respective clay and organic carbon contents in Fig. 3.6, as these parameters are most significantly related to the gastropod distributions. The ecological implications of the gastropod samples are indicated by differing signatures in Fig. 3.6.

3.4.5 Remains of non-mollusc organisms

Vertebrates

Tab. 3.2 Vertebrate taxa of the palaeo record represented by micro remains (teeth and bones) sorted by gastropod sample ID`s of the profile site BL.

Sample Taxon Ecology

BL 6 sp. Microtus indet. comp. Microtus arvalis (comp. Steiner, 1972)

BL 9 sp. Microtus indet. comp. Microtus arvalis

BL 19 sp. Mesocricetus brandti Common name Brandt`s Hamster, “The species occurs in dry open steppe habitat with cereals and wormwoods (Artemisia absinthium), or cereals and herbs. Sometimes consumes insects and other invertebrates. Often has burrows within colonies of Microtus arvalis and Microtus socialis.” (Kryštufek et al., 2008) BL 58 Microtus arvalis Common name field vole, which apparently prefers open vegetation with a higher degree of grass cover and low values of tree cover, a preference for open meadows (Miklos & Ziak, 2002) in Southern Caucasia, it is modern living in alpine zone up to 3800m near streams. It is found in a wide variety of open habitats including moist meadows, pastures, forest steppe, moist forest (Yigit et al., 2016). BL 59 sp. Microtus indet. comp. Microtus arvalis

BL 81 Insectivor insectivorous (e.g. hedgehog, mole or bat) (Erinaceomorpha, Soricomorpha or Chiroptera)

We found several tooth fragments, complete teeth and bones of small mammals. Remains that allowed a determination of taxa are listed in Tab. 3.2.

Arthropoda

Numerous arthropod remains have been found in the deposits, which could not be specified. However, the mandible of a beetle was found in sample 3 of the site BL, which can be assigned to the genus Lucanus. All eligible species of the genus live in warm, open, and relatively humid forests with Quercus, Fagus and Carpinus.

3.5 DISCUSSION

3.5.1 Derivation of palaeo ecosystems based on the distribution of modern gastropods

Modern gastropod fauna of the study area

The Caucasus region supports a very rich and highly endemic snail fauna, in which evolution has taken place in-situ over millions of years (Sysoev & Schileyko, 2009, Pokryszko et al., 2011, Tarkhnishvili et al., 2012). In addition, the Caucasus region is one of the biologically richest but at the same time most threatened regions on Earth and, according to Conservation International, one of the four Eurasian biodiversity hotspots (Myers et al., 2000, Zazanashvil et al., 2004). There are currently 318 land snail species listed, of which 66% are endemic (Walther et al., 2014). This high number of endemics contributes to a low level of knowledge about the specific ecological requirements of the Caucasian gastropod fauna. The most relevant literature in this context are the works of Akramovski (1949, 1976). The distribution of taxa is biased by a complex intersection of several factors. It is not yet fully understood which factors are best suited to explain the distribution of species within the Caucasus region, nevertheless we listed the known ecological demands of each species in the appendix (Tab. 3.7). In order to interpret the palaeo-record, we have assigned all relevant species to the vegetation zones as described by Aktramovski (1976). The allocation therefore applies to the specific local conditions in Southern Caucasia and partly deviates from the distribution patterns of the respective species in other distribution areas. The distribution of species may differ due to local climatic differences such as continentality, i.e. in dryer regions compared to more humid regions etc. (comp. Horsák et al., 2010). Additionally, different evolutionary conditions (dispersal ability, competition, topographic barriers, distance to refuges) influence the distribution of specific species. There is probably no environment today that corresponds to that of the Pleistocene, which was assumedly characterised by only weakly developed calcareous soils, strongly alternating climatic conditions and a hydrologic cycle that is different

65 from the recent one. The comparison with current conditions must therefore always be viewed with some reservation. In order to detect palaeo-specific distribution anomalies and to identify typically associated species in the past, we conducted a cluster analysis. This analysis is able to identify peculiarities in the distribution of species that may occur due to local specifics or palaeoclimatic conditions, and to distinguish between natural and anthropogenic triggers. Based on this cluster analysis and the ecological categorisations by Akramovski (1949 and 1976), we have assigned the (sub)fossil gastropod species to the modern Southern Caucasian vegetation types as shown in Fig. 3.7. These vegetation types correspond to orobiomes and partly include anthropogenic vegetation.

Climatic conditions derived from gastropod habitats

Based on the orographic ecological zones of Akramovski (1976) (Fig. 3.7), we have defined 4 ecological groups and 3 subgroups, which also find equivalents in the lateral geographic vegetation zones, corresponding to different climatic conditions. In a next step, we have assigned these climate-induced zonobiomes to the climate classification by Troll and Paffen (Troll-Paffen annual seasonality categories, see Landsberg et al., 1963) and suggest that palaeoclimatic conditions can be derived as shown in Figure 3.7. These climate conditions reflect a gradient in annual precipitation amounts as well as in average summer and winter temperatures. However, there are some problems in assigning current vegetation types to prehistoric environments. For example, it seems problematic to classify gastropod species, which live in the phryganoid vegetation today, as this vegetation type was probably created by degradation under pasture pressure and anthropogenic influences. Even these anthropogenic influences can hardly be quantified and vary locally. The pressure on the orobiomes in the continental central part of Southern Caucasia is particularly high for Armenia, since the largest part of the population settles there, which differs e.g. also from Georgia and Azerbaijan, where people live more in foothills and valleys (Dzhaoshwili et al., 1988). It has not been sufficiently investigated whether gastropod species living today in the young phryganoid vegetation should, under purely natural vegetation conditions, be allocated to semidesert shrub vegetation or whether phryganoid vegetation replaces more humid vegetation such as highgrass-steppes or even forests. In addition, the forest-steppe ecosystems in the study region were extensively displaced by deforestation and the spread of pastures. In contrast, it can be assumed that forest-steppes were possibly widespread in the study area during the Pleistocene interglacial periods. The distribution of gastropods in the sediments in combination with their ecological assignment is shown in the mollusc diagrams Figs. 3.2 and 3.3. In addition, the mollusc spectrum in Figure 3.8 shows the proportion of the ecological groups represented for each assemblage. Deviations in the assigned ecology between stratigraphic malacozones and the

66 contained individual taxa are based on the concept of ecotones, in which the species common to the neighbouring assemblages can coexist (see Van der Maarel, 1990). Such overlaps are further reinforced by the fact that each strata corresponds to a time period and not to a single time recording.

Fig. 3.7 Categorisation of (orographic) vegetation zones after Akramovski (1976) with modern distributions of the gastropod taxa recorded for sequences Sevkar and BL. The chart shows the equivalent ecotypes with assumed palaeovegetation and related environmental conditions as derived from Troll-Paffen categories. The arrow-bars show mean annual temperatures and precipitation related to particular vegetation types (after Walter & Breckle, 1994)

Fig. 3.8 Gastropod results (Mollusc spectrum and malacozonation) and sedimentological parameters

(lithofaciestypes, carbonate content and organic carbon content) for section BL correlated with n-alkane ratios of this study site (Trigui et al., 2019) and palynological record of Litt et al. (2014) for Lake Van. The legend can be taken from the legend in Fig. 3.3. A more detailed description of the lithofacies types is given in the supplementary material Tab. 3.1). We refer to the digital version for coloured figures. 68

3.5.2 What restricted tree growth during glacial phases – drought or cold?

Loess layers and interstadial palaeosols are characterised by the absence of gastropod species that live in forests and forest-steppes. This indicates that there was apparently no tree growth during glacial times. Basically, we consider two different types of treelines for the study area: a cold-induced alpine treeline and a drought-induced desert treeline (comp. Fig. 3.9). The desert treeline marks the area in which prolonged drought prevents tree growth. This is particularly the case in continental dry areas, where the vegetation period is typically interrupted by two periods of drought: once in summer by strong evaporation and once again in winter by the persistently solid state of the ground water. In comparison, the alpine treeline occurs when mean summer temperatures are below 6 – 8°C, biased by local specifics such as the prevalent bioclimate and occurring taxa (Körner & Paulsen, 2004, comp. D'Odorico et al., 2013). This cold-induced treeline of the alpine and arctic regions approximates the 10°C isotherm of average July temperatures (see inter alia Smithson et al., 2013). In order to determine whether tree growth during glacial periods has been prevented by the advancement of the alpine treeline or the desert treeline towards the study sites, we compared prevalent gastropod species for the different glacial phases. We looked for species which currently typically inhabit the alpine zone of Northeast Armenia such as Anatolya brevior, Caucasigena eichwaldi armeniaca and Karabaghia bituberosa, as these species should indicate an overall colder climate. However, the studied LPS did not contain these cold-adapted species. All the more, deposits and palaeosols linked to glacial times were represented by species such as K. crenimargo, G. interrupta, P. kyrostriata, P. aff. poltavica and Imparietula indet., which today typically live in habitats of summer-warm semideserts (e.g. shrub-steppes) and phryganoid vegetation. Nevertheless, it should be noted that gastropods are not primarily dependent on

Fig. 3.9 Proposed changes of treelines related to glacial-interglacial cycles in the study area.

69 temperatures, but rather on humidity conditions (see e.g., Obreht et al., 2019). Therefore, in comparison with recent ranges of species, it is still problematic to find equivalent ecosystems that could correspond to those of the Pleistocene. Nevertheless, since the gastropod species of glacial times do not contain cold-adapted species but correspond to xerophilic communities occurring in high continental (cool temperate) semideserts and shrub steppes, we assume for these sites that tree growth during glacial times was not limited by the descent of the alpine treeline under cold conditions, but that the desert treeline ascended from the Kura basin and prevented tree growth due to aridity. Therefore, we suggest that the average July temperatures during glacial times in the study area were above 10°C (comp. Fig. 3.7). The limiting factor for tree growth at the BL and Sevkar sites (630 m. a. s. l.) was therefore most probably drought, rather than low annual temperatures. This is in good agreement with the lithostratigraphic record, which shows no indications of permafrost.

In addition, it is striking that also in the pedocomplexes and even the interglacial periods included therein, the palaeo-record does not contain typical forest species as they occur in forest ecosystems of the modern study region such as Pomatias rivularis, Sphyradium doliolum or Acanthinula aculeata (see Tab. 3.8, comp. e.g., Cameron et al., 2013). Instead, taxa in the palaeo pedocomplexes rather contain species which can be allocated to forest-steppes with scattered trees and barren xerophilic forests at the most. This raises the question whether dense forest ecosystems did not occur or whether the related gastropod shells were not preserved. It is well known that snail shells are easier to dissolve under humid conditions and are mostly absent in palaeosols (comp. Ložek, 1990). The carbonate contents (Fig. 3.8) show that strong decalcification processes have taken place within the most intense palaeosols (linked to the mollusc samples BL 4 and BL 5 of pedocomplex P-0, BL 18, BL 19, BL 24 and BL 25 of pedocomplex P-1, BL 39, BL 40, BL 43 and BL 44 of pedocomplex P-2, and samples BL 54, BL 55, BL 58 and BL 59 of pedocomplex P-3) and related gastropod assemblages are characterised by a very small number of preserved shells (Malacozone F+). However, these shells are not restricted to the ecologically most robust species, but include more hygrophilous taxa such as V. pulchella or V. pygmaea. Given the small number of preserved shells, it is difficult to draw detailed conclusions about the palaeoecosystem. For example, the original assemblage could also have been dominated by forest species. This assumption may be reinforced by the fact that decalcification processes are distinct in forest ecosystems, which produce more aggressive fulvic and humic acids. Evidence for forest ecosystems is given by the remains of a stag beetle in sample BL 3 (Holocene age), which usually lives in oak forests (see Chap. 3.4.5). However, the gastropod results do not allow a reliable interpretation of palaeoconditions for the pedocomplexes, yet.

3.5.3 Differences between palaeosol-complexes

To identify environmental conditions related to the different pedocomplexes, we compared all associated gastropod assemblages. In addition, we investigated whether there is a relation between malacologically derived ecotypes and palaeosol features. Potential dependencies were tested by a significance test (comp. Chap. 3.4.4). Regarding to this, species of relatively more humid ecosystems such as e.g., X. derbentina, V. pulchella and V. pygmaea significantly correlate with increased organic carbon contents, while the grassland species M. pupoides and the presence of small mammal remains (comp. Chap. 3.4.5) significantly correlated with increased clay contents. Based on these results we plotted clay together with organic carbon contents for gastropod samples in combination with malacozones and ecotypes that they are assumed to represent. The assemblages with the highest proportion of forest (steppe) species in parallel show the highest contents in organic carbon, suggesting a higher Net Primary Productivity, biased by degradation and accumulation of the biomass. However, erosion of the uppermost soil layers should be considered. Since the loess deposits and palaeosols of the BL and Sevkar sections contain certain amounts of tephric material, the high organic content may be also caused by andosolisation. In Andosols, the coupling of allophanes and organic matter form bonds that are relatively stable, leading to (modern) soils that commonly show > 6% of organic carbon in both A and B horizons, and the typical dark colour. Although the palaeosols in the studied LPS cannot generally be classified as andosols according to the WRB, it is assumed that they might be partly based on similar soil formation processes. Andosolic processes might also explain the unusually high clay contents for the majority of the palaeosols with values of up to 60%. Therefore, andosolic processes, under humid edaphic conditions, can lead to rapid weathering of amorphous volcanic material to allophanes. Even if the clay content additionally varies depending on the initial composition of the source substrate (incl. content of tephric material, degree of reworking/relocation), it may also be an indicator for the intensity of weathering related to increased edaphic humidity. With respect to the compilation in Figure 3.6, it appears that a general transition from arid semi-desertic conditions to moister steppic conditions coincides with palaeosol samples showing a clay content of more or less 30%. Palaeosols with clay contents higher than 30% are related to shortgrass-steppe, highgrass-steppe, or forest-steppe, respectively. The fact that soils linked to shortgrass-steppe have similarly high clay contents than soils linked to forest-steppe (Fig. 3.6) shows that the intensity of clay formation does not follow the trend of continual increase of edaphic humidity that is usually associated with the transition of the different vegetation types. We thus assume that as soon as slightly higher edaphic moisture becomes available, processes of mineral weathering and secondary clay formation accelerated rapidly as a result of the transformation of volcanic glasses into amorphous clay minerals.

3.5.4 Comparison between sections Sevkar and Bl

Comparing the mollusc data of the Sevkar and BL sections, the loessic layers below P-1 for both sites are dominated by K. crenimargo and G. interrupta. The thanatocoenosis of the subsequent pedocomplex P-1, (Sevkar samples 2 and 3) can be assigned to malacozone E, characterised by high biodiversity and mesophilous species and coincides with BL samples 20 to 18. Between Sevkar samples 3 and 4 there is a strong decrease in biodiversity and species composition towards drier conditions, represented by semidesert and shortgrass-steppe species, which can equally be observed in BL samples 18 to 14. At both sites, these deposits are interrupted with a temporary absence of P. aff. poltavica (Sevkar samples 7 and 8, BL 12 and BL13), while the younger sediments (Sevkar samples 9 and 10) are characterised by a biodiverse semidesert shrub community and recurrence of P. aff. poltavica. The upper colluvial layer in both sections shows a similar taphocoenosis of ubiquitous species. Unlike BL, the Sevkar sequence does not contain shells of G. signata. However, the stratigraphic units of BL representing the peak phases of G. signata (malacozone B and C) have not been sampled at the Sevkar site. Nevertheless, solitary shells of G. signata in the lower part of BL might indicate that the latter, due to its S/SW exposure, receives more solar radiation than the NE/E exposed site of Sevkar, thus favouring the spread of the thermophilous G. signata. Altogether, the close match of associations in related stratigraphic units across the both sections indicates that the succession and composition of malacozones seems to be consistent over the study area.

3.5.5 Reconstruction of palaeoecosystems and humidity conditions

The investigated LPS archive at least the last three glacial-interglacial cycles, whereat the temporal classification should be considered with caution, since luminescence dating is still in progress. With regard to a chronological assignment, it should also be noted that the temporal connection between marine isotope stages and the formation of loess deposits and palaeosols, respectively, is still problematic, since the ongoing coupling processes and potential reaction shifts are not yet fully understood (Bolikovskaya & Molodkov, 2006, Zeeden et al., 2018). However, based on biostratigraphic patterns of the gastropod records and first preliminary luminescence age estimates (see Fig. 3.2, Fig. 3.8), we assume that within the LPS, parts of the pedocomplexes (presumably the lowermost palaeosols of the pedocomplexes) refer to interglacial periods (i.e., MIS 5e, MIS 7, MIS 9). Based on their contained gastropod fauna, we furthermore assume these interglacial phases to be assigned to generally more humid conditions (see Fig. 3.8). The corresponding assemblages are represented by species e.g. of the V. pulchella – C. tridens zone (MZ E) or V. pygmaea zone (MZ B), containing taxa that occur in highgrass- and forest-steppes (comp. Fig. 3.2). The parallel prevalence of vertebrate remains (e.g. in BL 6, BL 9, BL 13, BL 58 & 59) assigned to open grassland to forest-steppe

72 ecosystems (comp. Chap. 3.4.5) supports these results. These ecosystems typically correspond to an average annual precipitation above 300 mm. The increased humidity is consistent with the findings of Djamali et al. (2008), who investigated pollen records and concluded warmer and moister conditions for interglacial periods, indicated for Lake Urmia by forest-steppe species with Quercus, Juniperus and Pistacia. While mollusc shells are usually well preserved in pure (calcareous) loess, they are quickly corroded and dissolved in (fossil) soils and aeolian loams (comp. Ložek, 1990, Říhová et al., 2018, Chap. 3.5.2). For example, any data on stratigraphic features and soil analytical measurements indicate that the lowest palaeosol of pedocomplex P-1 at BL (depth 7 to 8 m, Fig. 3.2) represents a distinct soil of interglacial times. However, gastropod analyses revealed a poor preservation status of mollusc shells due to intense dissolution processes within the decalcified soil horizons. These preservation problems of gastropod shells in intensely developed palaeosols have also been observed in adjacent study areas such as the Ukrainian loess archives (Alexandrowicz et al., 2014). Thus, a detailed statement about the ecosystems for these periods is complicate for now.

We furthermore assume, as discussed in Chap. 3.5.1 to 3.5.3, that glacial times related to loess deposition, are generally characterised by dryer conditions compared to the interglacial and interstadial periods linked to pedogenesis. In these dry phases, semidesert species such as K. crenimargo, G. interrupta and Imparietula indet. occur. However, we observed significant differences between different glacial-interglacial cycles. Deposits directly below pedocomplex P-3 that were tentatively assigned to MIS 10 (see chronological allocation in Fig. 3.8) contain rich gastropod associations of the abundant M. pupoides - C. tridens zone (MZ G+) typical of dry harsh grassland ecosystems. They can probably be assigned to the xerophilous shortgrass-steppes. Mollusc associations assumedly linked to the subsequent glacial period contemporaneous with MIS 8 (between pedocomplexes P-3 and P-2) are related to a mixture of M. pupoides - C. tridens fauna (MZ G) and K. crenimargo - G. interrupta - P. aff. poltavica zone (MZ D+). They indicate comparably more arid conditions including both, species of shortgrass-steppe and shrub-steppe ecosystems. We assume that these communities lived in a transitional zone between both vegetation types, possibly characterised by dry grasslands with scattered Artemisia shrub. Within the last two glacials (MIS 2-4 and MIS 6), an increase in gastropod species typical of semidesert habitats can be observed. They are represented by the K. crenimargo - G. interrupta – P. aff. poltavica zone (MZ D+) and K. crenimargo - G. interrupta zone (MZ D). We suppose that these communities lived in dry shrub steppes. We therefore assume an increase in drought towards semiarid to fully arid climatic conditions. Based on the absence of typical cold-resistant species (Chap. 3.5.2), it is assumed that temperatures in July were above 10°C (comp. Chap. 3.5.2). A comparison of the two periods

73 reveals a difference in the biodiversity of gastropods. Lower species richness in semidesert- assemblages during MIS 6 compared to the last glacial period may have been caused by higher geomorphological instability and activity during MIS 6. The deposits which are assumedly linked to MIS 6, reveal increased fine sand contents (comp. Wolf et al., 2016). These may indicate higher wind strengths in dry phases on one hand, but on the other hand also an increased tephra input, since the fine sand grains consist predominantly of volcanic glasses. An increased volcanic influence would also affect the gastropods, since, for example, in the tephra layer (sample BL 32) only the most adaptable and robust species, G. interrupta and K. crenimargo, survived (comp. Fig. 3.2). This species poverty as in sample BL 32 in combination with comparatively high abundances of the individual species is typical for stressed ecosystems. For the last glacial, in contrast, richer semidesert environments interlocked with occurrences of more hygrophilous species such as V. pulchella (samples BL 8 and BL 13) might point to sections that were not only characterised by stability but also by increased humidity. These fluctuations within the last glacial period have also been observed by Pickarski et al. (2015) for the Lake Van area and may indicate the succession of several stadial and interstadial periods. Overall, with respect to the different glacial periods characterised by loess deposition, we found clear indications for a steady increase in aridity from the bottom to the top of the LPS (see Fig. 3.8).

A similar situation has been reported for LPS in the southeast-central European lowlands of the Carpathian and Lower Danube Basins (Buggle et al., 2013, Obreht et al., 2016, Obreht et al., 2019). Our results reinforce an aridisation trend for the last three glacial cycles. Supplementary to these studies, we found the strongest evidence for aridisation among the different glacial phases. A possible explanation for this aridisation could be, as proposed inter alia by Buggle (2013) and Obreht (2016, 2019) the continual uplift of the Alpine-Himalayan orogenic belt (see Mosar et al., 2010, Robl et al., 2015), leading to increased rain shadows of Eurasian mountain chains. The uplift of the Caucasus region is very heterogeneous. Assuming a mean uplift rate of about 1 mm/a (comp. Mosar et al., 2010), the total uplift across our sequence would be about 300 m, which might have biased peri-mountainous atmospheric patterns. Although we do not yet have a clear explanation for the causes of this aridisation trend, our results, similar to those of Liang et al. (2016) for the sea of Azov region, indicate a supra-regional trend (comp. Obreht et al., 2019). In this context, it should be the task to explore further Eurasian archives, also outside the influence of orogens, in order to consolidate the data. This would help to find possible explanations for the fluctuations in atmospheric circulation, which may be related e.g. to variations in atmospheric composition or Milankovic cycles (comp. Zech et al., 2011, Obreht et al., 2019).

In order to make a comparison with other bioproxies, we compared the results of this gastropod

74 analysis with n-alkane ratios measured at the BL profile (Trigui et al., 2019) and pollen records from Lake Van (Litt et al., 2014) (see Fig. 3.8). In general, the results of the gastropod analysis match with the results shown by Litt et al. (2014) for Lake Van. Interglacial periods at Lake Van (situated 1600 m a.s.l.) show a significant presence of arboreal pollen indicating an oak-steppe forest with pistachio and juniper, while glacial periods were dominated by non-arboreal pollen implying dwarf-shrub and desert steppe ecosystems.

The results of the n-alkane analyses by Trigui et al. (2019) show a dominance of the alkane chain length nC29 for periods characterised by loess deposition. Related n-alkane ratios are generally interpreted as an indication of dominating woody plant taxa. However, tree growth during glacial periods contradicts with the absence of equivalent gastropod species. One explanation for these alkane signals could be that the alkane record is not dominated by the type of vegetation but by changing chemotaxic processes as has been observed by Markovic et al. (2018) at loesses of the Carpathian basin. This is contradicted, however, by the fact that the Serbian loesses were constantly dominated by grass, whereas in BL (this study) we observed a significant decrease in grasses and herbs of up to 0% in the glacial phases (BL sample 36, see Trigui et al., 2019), indicating a significant change in vegetation type. Trigui et al. (2019) discuss several possible influences on the alkane signals and show their high complexity. However, since the gastropod species of the loess deposits in BL today feed mainly on xerophilous Artemisia shrub, we suspect that the glacial n-alkane signals might represent this shrub signal, too. As many shrub taxa have similar alkane chain lengths to trees, also Artemisia species show a dominance of nC29 alkanes (Wang et al., 2018). Furthermore, Wang et al. (2018) report that leaf wax n-alkane productions were similar for all species within the same genus and thus dominated by their phylogeny, independent of their plant functional types (Wang et al., 2018) (also comp. Rao et al., 2011). As a consequence, there would be no difference between Artemisia species which grow in a mesophilous forest and desert shrub species of Artemisia. The assumption of a shrub domination during colder and dryer phases would also be consistent with the palynological record of Litt et al. (2014), which shows a high proportion of Artemisia pollen during glacial periods. If we consider the recent vegetation of the driest locations of the Caucasus region and Central Asian semideserts, it is similarly characterised by high abundances of xerophilic Artemisia shrub species. In summary, based on the data available to date, we assume that glacial periods in our study area were dominated by an Artemisia shrub steppe (e.g. with Artemisia fragrans).

Furthermore, the dominance of grass-derived n-alkanes within the pedocomplexes of the studied LPS (Trigui et al., 2019) could confirm the presence of grass-dominated forest steppes rather than dense forest ecosystems. These initial results show that it is possible to derive more detailed information by examining and comparing several biological proxies and thus to

75 obtain an increasingly uniform picture of the palaeo-landscape.

3.6 CONCLUSION

In this study, we performed gastropod analyses on loess-palaeosol sequences in northeast Armenia (Southern Caucasia), covering at least three glacial-interglacial cycles. In order to derive information about palaeoecological conditions, we elaborated an ecostratigraphy and assigned corresponding malacozones to certain ecotypes. Accordingly, we assume more humid conditions during the formation of pedocomplexes that might be related to interglacial and subsequent interstadial phases. According to our results, the corresponding ecosystems were characterised by highgrass- and forest-steppe. In addition, we found no evidence of a dense forest cover. However, it should be noted that the preservation of shells in intensively developed palaeosols can be poor, as decalcification processes, particularly under forest ecosystems, are likely. In contrast, loess and loess-like deposits that we relate to glacial (stadial) periods contain species communities that occur primarily in semidesert ecosystems today. For these deposits, we additionally found a trend towards steadily increasing drought from the bottom to the top of the profiles indicating progressive aridification through the Middle to Upper Pleistocene period. While the lower part of the LPS was dominated by rich shortgrass- steppe ecosystems, the middle part indicates ecosystems with both, shrub-steppe and shortgrass-steppe. Subsequently, deposits formed during MIS 6 seem to be related with species-poor shrub-steppe and high geomorphologic activity, while deposits linked to the last glacial period indicate a species-rich shrub-steppe intercalated with sections of stability and improved conditions for gastropods (series of stadial and interstadial phases). The results also suggest that ecosystems during glacial periods were more stressed by drought rather than by cold, and that average temperatures in July were presumably above 10°C all the time. We therefore propose for the studied sites that environmental changes at the transition from interglacial to glacial periods were not characterised by the descend of a cold-induced treeline from the alpine zone, but rather that a drought-induced treeline spread from the Kura Basin to the higher altitudes of our investigated sections. In this study, quaternary gastropods were used as palaeo proxies in the Caucasus region for the first time. Based on gastropod analyses, we were able to extract detailed information for this little-known loess distribution area, enabling to merge the knowledge for European and Asian sediment archives. In the past, biological proxies and geochemical parameters often showed contradictory results, particularly in the adjacent study areas. We therefore recommend that archives should always be interpreted with a multi-proxy approach, as especially biological proxies such as gastropods can help to obtain a coherent picture of the palaeo landscape.

3.7 ACKNOWLEDGEMENT

We are very grateful to Dr. Lutz Christian Maul (Senckenberg Institute, Weimar) for his help in the determination of vertebrate remains. We sincerely thank Dr. Maria Neubauer (TU Dresden) for consultment in statistics and Dr. Fritz Haubold (TU Dresden), Florian Schneider (University of Göttingen) and Philipp Baumgart (TU Dresden) for their help with fieldwork. We are furthermore grateful to Dr. Nadine Pickarski (University of Bonn) for the determination of the seeds and to Yesmine Trigui (TU Dresden), Prof. Michael Zech (TU Dresden) and Prof. Roland Zech (University of Jena) for beneficial discussions. We sincerely thank the two anonymous reviewers and the editor for their time and helpful advice, which has considerably improved the quality of the manuscript. This work was funded by the German Research Foundation (DFG, FA 239/21-1) and the basic state research of the Republic of Armenia, Ministry of Education and Science of Armenia Science Committee. The work of the first author was financed by a graduate research scholarship of the TU Dresden.

3.8 REFERENCES

Akramovski, N. N. (1949). Terrestrial Mollusca in the territory of the Settlement Gnishik in Soviet Armenia. Akademiya Nauk Armyanskoj SSR, 6, 127-183.

Akramowski, N.N. (1976). Fauna of Armenian SSR: Mollusks (Mollusca). 1–268, Akademiya Nauk Armyanskoj SSR, Yerevan.

Alexandrowicz, W. P., Boguckyj, A., Dmytruk, R. & Łanczont, M. (2002). Molluscs of loess deposits in the Halyč Prydniestrov`ja region. Studia Geologica Polonica, 119, 253-290 & 359- 360.

Alexandrowicz, W. P., Łanczont, M., Boguckyj, A. B., Kulesza, P. & Dmytruk, R. (2014). Molluscs and ostracods of the Pleistocene loess deposits in the Halych site (Western Ukraine) and their significance for palaeoenvironmental reconstructions. Quaternary Science Reviews, 105, 162-180.

Antoine, P., Rousseau, D.-D., Moine O., Kunesch, S., Hatté C., Lang, A., Tissoux, H. & Zöller, L. (2009). Rapid and cyclic aeolian deposition during the Last Glacial in European loess: a high-resolution record from Nussloch, Germany. Quaternary Science Reviews, 28, 2955-2973.

Bolikhovskaya, N. S., & Molodkov, A. N. (2006). East European loess-palaeosol sequences: palynology, stratigraphy and correlation. Quaternary International, 149(1), 24-36.

Bonham, K. (2005). Cecilioides acicula (Müller, 1774) (Pulmonata: Ferussaciidae), a burrowing land snail introduced to Tasmania. The Tasmanian Naturalist, 127: 42-44.

Brochier, J., Barge, O., Karakhanyan, A., Kalantaryan, I., Chataigner, C., Chambrade, M. & Magnin, F. (2014). The Aragats Kites In Armenia. Paléorient, 40, 25-53.

Buggle, B., Hambach, U., Kehl, M., Marković, S. B., Zöller, L. & Glaser, B. (2013). The progressive evolution of a continental climate in southeast-central European lowlands during the Middle Pleistocene recorded in loess paleosol sequences. Geology, 41, 771-774.

Buylaert, J.P., Murray, A.S., Thomsen, K.J., Jain, M. (2009). Testing the potential of an elevated temperature IRSL signal from K-feldspar. Radiation Measurements 44, 560–565.

Cameron, R. A., Pokryszko, B. M., & Horsák, M. (2013). Forest snail faunas from Crimea (Ukraine), an isolated and incomplete Pleistocene refugium. Biological journal of the Linnean Society, 109(2), 424-433.

Danukalova, G. A., Yakovlev, A.G., Morozova, E.M. & Alimbekova, L.I. (2007). Biostratigraphy of the late middle pleistocene (Middle Neopleistocene) of the southern Urals region. Quaternary International, 160, 17-29.

Danukalova, G., Osipova, E., Khenzykhenova, F. & Sato, T. (2015). The molluscs record: A tool for reconstruction of the Late Pleistocene (MIS 3) palaeoenvironment of the Bolshoj Naryn site area (Fore-Baikal region, Eastern Siberia, Russia). Quaternary International, 355, 24-33.

Djamali, M., de Beaulieu, J. L., Shah-Hosseini, M., Andrieu-Ponel, V., Ponel, P., Amini, A. & Brewer, S. (2008). A late Pleistocene long pollen record from Lake Urmia, NW Iran. Quaternary

Research, 69(3), 413-420.

D'Odorico, P., He, Y., Collins, S., De Wekker, S., Engel, V. & Fuentes, J. (2013). Vegetation– microclimate feedbacks in woodland–grassland ecotones. Global Ecology and Biogeography, 22(4), 364-379.

Dodonov, A. E. & Baiguzina, L. L. (1995). Loess stratigraphy of Central Asia: palaeoclimatic and palaeoenvironmental aspects. Quaternary Science Reviews, 14(7), 707-720.

Dzhaoshwili et al. (1988). In: Walter, H., & Breckle, S. W. (eds.). Ökologie der Erde. Band 3. Spezielle Ökologie der Gemässigten und Arktischen Zone Euro-Nordasiens, 2. Aufl. Gustav Fischer, Stuttgart, 237.

Gobejishvili, R. (2004). Late Pleistocene (Würmian) glaciation of the Caucasus. In: Ehlers, J. & Gibbard, P. L. (eds.). Quaternary Glaciations–Extent and Chronology. Part I: Europe. Elsevier, Amsterdam, 129–134..

Horsák, M., Chytrý, M., Pokryszko, B.M., Danihelka, J., Ermakov, N., Hájek, M., Hájková, P., Kintrová, K., Kočí, M., Kubešová, S., Lustyk, P., Otýpková, Z., Pelánková, B. & Valachovič, M. ( 2010). Habitats of relict terestrial snails in southern Siberia: lessons for the reconstruction of palaeoenvironments of full‐glacial Europe. Journal of Biogeography, 37, 1450– 1462.

Horsák M., Limondin-Lozouet N., Jurickova L., Granai S., Horackova J., Legentil C., Lozek V. , (2019). Holocene succession patterns of land snails across temperate Europe: east to west variation related to glacial refugia, climate and human impact. , Palaeogeography, Palaeoclimatology, Palaeoecology , 524, 13-24.

Jefferson, I. F., Evstaviev, D., Karastanev, D., Mavlyanova, N. G., Smalley, I. J. (2003). Engineering geology of loess and loesslike deposits: a commentary on the Russian literature. Engineering Geology, 68, 331–351.

Joannin, S., Cornée, J. J., Münch, P., Fornari, M., Vasiliev, I., Krijgsman, W., Nahapetyan, S.,

Gabrielyan, I., Ollivier, V., Roiron, P. & Chataigner, C. (2010). Early Pleistocene climate cycles in continental deposits of the Lesser Caucasus of Armenia inferred from palynology, magnetostratigraphy, and 40Ar/39Ar dating. Earth and Planetary Science Letters, 291(1-4), 149-158.

Juřičková, L., Horsák, M., Horáčková, J., Abraham, V., & Ložek, V. (2014). Patterns of landsnail succession in Central Europe over the last 15,000 years: main changes along environmental, spatial and temporal gradients. Quaternary Science Reviews, 93, 155-166.

Körner, C., & Paulsen, J. (2004). A world‐wide study of high altitude treeline temperatures. Journal of Biogeography, 31(5), 713-732.

Kryštufek, B., Yigit, N. & Amori, G. (2008). Mesocricetus brandti. The IUCN Red List of Threatened Species 2008: e.T13220A3421550. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T13220A3421550.en. Downloaded on 25 February 2019.

Kwiecien, O., Stockhecke, M., Pickarski, N., Heumann, G., Litt, T., Sturm, M., Anselmetti, F., Kipfer, R. & Haug, G. H. (2014). Dynamics of the last four glacial terminations recorded in Lake Van, Turkey. Quaternary Science Reviews, 104, 42-52.

Landsberg, H. E., Lippmann, H., Paffen, K. H. & Troll, C. (1963). World Maps of Climatology. World Maps of Climatology.

Legendre, P. & Legendre, L. (1998). Numerical Ecology (Developments in Environmental Modelling). Elsevier Ltd, 2nd edition, Oxford.

Liang, Y., Yang, T. B., Velichko, A. A., Zeng, B., Shi, P. H., Wang, L. D., He Y., Chen J. & Chen, Y. (2016). Paleoclimatic record from Chumbur-Kosa section in Sea of Azov region since Marine Isotope Stage 11. Journal of Mountain Science, 13(6), 985-999.

Limondin-Lozouet, N., & Preece, R. C. (2014). Quaternary perspectives on the diversity of land

80 snail assemblages from northwestern Europe. Journal of Molluscan Studies, 80(3), 224-237.

Litt, T., Pickarski, N., Heumann, G., Stockhecke, M., & Tzedakis, P. C. (2014). A 600,000 year long continental pollen record from Lake Van, eastern Anatolia (Turkey). Quaternary Science Reviews, 104, 30-41.

Ložek, V. (1990). Molluscs in loess, their paleoecological significance and role in geochronology - Principles and methods. Quaternary lnternational, 7(8), 71-79.

Lydolph, P. E. (1977). Climates of the Soviet Union. Elsevier Scientific Publishing Company, Amsterdam.

Marković, S.B., Stevens, T., Kukla, G.J., Hambach, U., Fitzsimmons, K.E., Gibbard, P., Buggle, B., Zech, M., Guo, Z., Hao, Q., Wu, H., O'Hara Dhand, K., Smalley, I.J., Újvári, G., Sümegi, P., Timar‐Gabor, A., Veres, D., Sirocko, F., Vasiljević, D.A., Jary, Z., Svensson, A., Jović, V., Lehmkuhl, F., Kovács, J. and Svirčev, Z. ( 2015). Danube loess stratigraphy — Towards a pan‐ European loess stratigraphic model. Earth Science Reviews, 148, 228– 258.

Meszner, S., Fuchs, M. & Faust, D. (2011). Loess-Paleosol-Sequences from the loess area of Saxony (Germany). Quaternary Science Journal, 60(1), 47-65.

Miklos, P. & Ziak, D. (2002). Microhabitat selection by three small mammal species in oak-elm forest. Folia Zoologica Praha, 51(4), 275-288.

Moine, O., Rousseau, D. D. & Antoine, P. (2008). The impact of Dansgaard-Oeschger cycles on the loessic environment and malacofauna of Nussloch (Germany) during the Upper Weichselian. Quaternary Research, 70(1), 91-104.

Morisita, M. (1959). Measuring of interspeciﬁc association and similarity between communities. Memoirs oft he Faculty of Science, Kyushu University, Series E (Biology), 3(1), 65-80.

Mosar, J., Kangarli, T., Bochud, M., Glasmacher, U. A., Rast, A., Brunet, M. F., & Sosson, M. (2010). Cenozoic-Recent tectonics and uplift in the Greater Caucasus: a perspective from Azerbaijan. Geological Society, London, Special Publications, 340(1), 261-280.

Muhs,D. R. & Bettis, E. A. (2003). Quaternary loess-paleosol sequences as examples of climate-driven sedimentary extremes. In: Chan, M.A. & Archer, A.W.(Eds.). Extreme depositional environments: Mega endmembers in geologic time: Boulder, Colorado. Geological Society of America Special Paper, 53–74.

Myers, N., Mittermeier, R.A., Mittermeier, C.G., da Fonseca, G.A.B. & Kent. J. (2000). Biodiversity hotspots for conservation priorities. Nature, 403, 853-858.

Obreht, I., Zeeden, C., Hambach, U., Veres, D., Marković, S.B., Bösken, J., Svirčev, Z.,

Bačević, N., Gavrilov, M.B. & Lehmkuhl, F. (2016). Tracing the influence of

Mediterranean climate on Southeastern Europe during the past 350,000 years. Scientific Reports 6, 36334.

Obreht, I., Zeeden, C., Hambach, U., Veres, D., Marković, S. B. & Lehmkuhl, F. (2019). A critical reevaluation of palaeoclimate proxy records from loess in the Carpathian Basin. Earth- Science Reviews, 190, 498-520.

Osipova, E. & Danukalova G. (2011). Successions of Quaternary mollusc fauna in easternmost continental Europe (southern Urals, Russia). Quaternary International, 231, 44-49.

Pecsi, M. & Richter, G. (1996). Löss: Herkunft - Gliederung - Landschaften. Zeitschrift für Geomorphologie, Supplementband 98, Berlin.

Penkman, K. E. H., Preece, R. C., Bridgland, D. R., Keen, D. H., Meijer, T., Parfitt, S. A., White, T. S. & Collins, M. J. (2011). A chronological framework for the British Quaternary based on Bithynia opercula. Nature 476, 446-449.

Pickarski, N., Kwiecien, O., Langgut, D. & Litt, T. (2015). Abrupt climate and vegetation variability of eastern Anatolia during the last glacial. Climate of the Past, 11(11), 1491-1505.

Pickarski, N., & Litt, T. (2017). A new high-resolution pollen sequence at Lake Van, Turkey: insights into penultimate interglacial–glacial climate change on vegetation history. Climate of the Past, 13(6), 689-710.

Pokryszko, B. M., Cameron, R. A. D., Mumladze, L. & Tarkhnishvili, D. (2011). Forest snail faunas from Georgian Transcaucasia: patterns of diversity in a Pleistocene refugium. Biological Journal of the Linnean Society, 102, 239–250.

Rao, Z., Wu, Y., Zhu, Z., Jia, G. & Henderson, A. (2011). Is the maximum carbon number of long-chain n-alkanes an indicator of grassland or forest? Evidence from surface soils and modern plants. Chinese Science Bulletin 56, 16, 1714-1720.

Richter, C., Roettig, C. B., Wolf, D., Groh, K., Kolb, T. & Faust, D. (2019). Changes in Pleistocene gastropod faunas on Fuerteventura (Canary Islands) and implications on shifting palaeoenvironmental conditions. Quaternary Science Reviews, 209, 63-81.

Říhová, D., Janovský, Z., Horsák, M., & Juřičková, L. (2018). Shell decomposition rates in relation to shell size and habitat conditions in contrasting types of Central European forests. Journal of Molluscan Studies, 84(1), 54-61.

Robl, J., Prasicek, G., Hergarten, S., & Stüwe, K. (2015). Alpine topography in the light of tectonic uplift and glaciation. Global and Planetary Change, 127, 34-49.

Rousseau, D. D., Derbyshire, E., Antoine, P. & Hatté, C. (2006). European loess records. In S. Elias (ed.). Encyclopedia of Quaternary, 1440– 1456, Elsevier, Amsterdam.

Schaetzl, R.J., Bettis, E.A., Crouvi, O., Fitzsimmons, K.E., Grimley, D.A., Hambach, U., Lehmkuhl, F., Markovi, S.B.ć., Mason, J.A., Owczarek, P., Roberts, H.M., Rousseau, D.‐D., Stevens, T., Vandenberghe, J., Zárate, M., Veres, D., Yang, S., Zech, M., Conroy, J.L., Dave, A.K., Faust, D., Hao, Q., Obreht, I., Prud'homme, C., Smalley, I., Tripaldi, A., Zeeden, C. and Zech, R. ( 2018). Approaches and challenges to the study of loess - Introduction to the LoessFest Special Issue. Quaternary Research, 89, 563– 618.

Smithson, P., Addison, K. & Atkinson, K. (2013). Fundamentals of the physical environment. Routledge, p. 620.

Steiner, H. M. (1972). Systematik und Ökologie von Wühlmäusen (Microtinae, Mammalia) der vorderasiatischen Gebirge Ostpontus, Talysch und Elburs. Sitzungsberichte der Akademie der Wissenschaften mathematisch-naturwissenschaftliche Klasse, 180 (5-7), 99-193.

Steklov, A. A. (1966). Terrestrial Neogene mollusks of Ciscaucasia and their stratigraphic importance. Transactions, 163.

Stoica, M., Lazar, I., Vasiliev, I. & Krijgsman, W. (2007). Mollusc assemblages of the Pontian and Dacian deposits from the Topolog-Arges area (southern Carpathian foredeep) Romania. Geobios, 40, 391–405.

Sümegi, P., Gulyás, S., Molnár, D., Sümegi, B. P., Almond, P. C., Vandenberghe, J., Zhou, E., Pál-Molnár, E., Törőcsik, T., Hao, Q. Smalley, I., Molnár, M. & Marsi, I. (2018). New chronology of the best developed loess/paleosol sequence of Hungary capturing the past 1.1 ma: Implications for correlation and proposed pan-Eurasian stratigraphic schemes. Quaternary Science Reviews, 191, 144-166.

Sysoev, A. & Schileyko, A. (2009). Land snails and slugs of Russia and adjacent countries. Pensoft, Sofia & Moscow.

Tarkhnishvili, D., Gavashelishvili, A. & Mumladze, L. (2012). Palaeoclimatic models help to

84 understand current distribution of Caucasian forest species. Biological Journal of the Linnean Society, 105, 231–248.

Trigui, Y., Wolf, D., Sahakyan, L., Hovakimyan, H., Sahakyan, K., Zech, R., Fuchs, M., Wolpert, T., Zech, M. & Faust, D (2019). First Calibration and Application of Leaf Wax n-Alkane Biomarkers in Loess-Paleosol Sequences and Modern Plants and Soils in Armenia. Geosciences, 9, 263.

Van der Maarel, E. (1990). Ecotones and ecoclines are different. Journal of Vegetation Science, 1(1), 135-138.

Vlaminck, S., Kehl, M., Rolf, C., Franz, S.O., Lauer, T., Lehndorff, E., Frechen, M. and Khormali, F. (2018). Late Pleistocene dust dynamics and pedogenesis in Southern Eurasia – Detailed insights from the loess profile Toshan (NE Iran). Quaternary Science Reviews, 180, 75– 95.

Walther, F., Kijashko, P., Harutyunova, L., Mumladze, L., Neiber, M. T. & Hausdorf, B. (2014). Biogeography of the land snails of the Caucasus region. Tentacle, 22, 3-5.

Walter, H. & Breckle, S. W. (1984). Ökologie der Erde: Band 2: Spezielle Ökologie der Tropischen und Subtropischen Zonen. Stuttgart: Gustav Fischer Verlag.

Wang, J., Xu, Y., Zhou, L., Shi, M., Axia, E., Jia, Y., Chen, Z., Li, J. & Wang, G. (2018). Disentangling temperature effects on leaf wax n-alkane traits and carbon isotopic composition from phylogeny and precipitation. Organic Geochemistry, 126, 13-22.

Wolf, D., Baumgart, P., Meszner, S., Fülling, A., Haubold, F., Sahakyan, L., Meliksetian, K. & Faust, D. (2016). Loess in Armenia - stratigraphic findings and palaeoenvironmental indications. Proceedings of the Geologists' Association, 127(1), 29-39.

Yigit, N., Hutterer, R., Kryštufek, B. & Amori, G. 2016. Microtus arvalis. The IUCN Red List of Threatened Species 2016. e.T13488A22351133.

85 http://dx.doi.ožLorg/10.2305/IUCN.UK.2016-2.RLTS.T13488A22351133.en. Downloaded on 25 February 2019.

Zazanashvili, N., Gagnidze, R. & Nakhutsrishvili, G. (2000). Main types of vegetation zonation on the mountains of the Caucasus. Acta Phytogeographica Suecica, 85, 7-16.

Zazanashvili, N., Sanadiradze, G., Bukhnikashvili, A., Kandaurov, A. & Tarkhnishvili, D. (2004). Caucasus. In: Mittermaier R. A., Gil P. G., Hoffmann M., Pilgrim J., Brooks T., Mittermaier C. G., Lamoreux J., da Fonseca G. A. B.(eds.). Hotspots revisited, Earth’s biologically richest and most endangered terrestrial ecoregions. Sierra Madre: CEMEX/ Agrupacion Sierra Madre, 148–153.

Zech, W., Zech, R., Zech, M., Leiber, K., Dippold, M., Frechen, M., Bussert, R. & Andreev, A. (2011). Obliquity forcing of Quaternary glaciation and environmental changes in NE Siberia. Quaternary International, 234(1-2), 133-145.

Zeeden, C., Hambach, U., Obreht, I., Hao, Q., Abels, H. A., Veres, D., Lehmkuhl, F., Gavrilov, M. B. & Marković, S. B. (2018). Patterns and timing of loess-paleosol transitions in Eurasia: Constraints for paleoclimate studies. Global and planetary change, 162, 1-7.

3.9 SUPPLEMENTARY MATERIAL

Tab. 3.3 Supporting information on the luminescence dating procedure.

Method:

Luminescence measurements were performed using the polymineral fine grain fraction (4 – 11 µm). Sample preparation was done under subdued amber light (590 ± 10 nm), following standard procedures. After wet sieving, the sample material was treated with HCl and H2O2 to remove the carbonate and organic fraction. Afterwards, the fine grain fraction was separated by settling using Stokes’ law. Finally, the polymineral fine grain separates were pipetted onto stainless steel cups. All luminescence measurements were performed using a Lexsyg SMART luminescence reader (Richter et al., 2015), equipped with a 90Sr/90Y β-source for artificial irradiation (dose rate: ~ 0.117 Gy/s for fine grain material on stainless steel cups). For signal stimulation, infrared LEDs (850 ± 30 nm, 200 mW/cm2) were used. Luminescence signals were detected using a Hamamatsu H7360 photomultiplier in combination with a 3.5 mm AHF-Brightline HC 414/46 interference filter combined with a 3 mm Schott-BG 39 glass filter, resulting in a detection window centred at 410 nm. Data analysis was performed using an R-script based on the R-package “Luminescence”, version 0.9.5 (Kreutzer et al., 2012, 2019). For equivalent dose (De) determination, a modified post-IR IRSL225 protocol (Buylaert et al., 2009) was applied in order to minimize effects of anomalous fading. Following this procedure, the IR50 and the subsequent post-IR225 signal were each recorded for 300 s after a preheat step at 250 °C for 60 s. A hot-bleach step was not included in the measurement sequence. After measuring the natural signal, six regenerated cycles were used to define the dose response curve, fitted by a single exponential function. The signal integration limits for De determination were set to the initial 5 s of the IRSL signal, after subtracting a background from the last 100 s of the recorded signal. Up to 8 Aliquots were measured to determine the De. After passing the rejection criteria (recycling ratio: 10%, recuperation value: 5%, palaeodose and test dose error: 15%) the mean De for every sample was calculated using the unweighted arithmetic mean with the standard error of the mean. For dose rate (Ḋ) determination, radionuclide concentrations (U, Th, K) were measured using a µDose-System (combined α- and β-counter, Tydka et al., 2018). The determination of the dose rate is based on conversion factors of Guerin et al. (2011). Cosmic dose rates were calculated following Prescott and Hutton (1994). Furthermore, an a-value of 0.086 ± 0.004 (Rees-Jones, 1995) and an internal potassium content of 12.5

± 0.5% (Huntley & Baril, 1997) were considered. A water content of 15 ± 7.5% was assumed, based on the pore volume of the sample material, also considering the measured in situ water content. All dose rates were calculated using the Dose Rate Calculator DRAC v1.2 (Durcan et al. 2015).

References:

Buylaert, J.P., Murray, A.S., Thomsen, K.J., Jain, M. (2009). Testing the potential of an elevated temperature IRSL signal from K-feldspar. Radiation Measurements 44, 560–565.

Durcan, J.A., King, G.E., Duller, G.A.T. (2015). DRAC: Dose Rate and Age Calculator for trapped charge dating. Quaternary Geochronology 28, 54-61.

Guérin, G., Mercier, N., Adamiec, G. (2011). Dose-rate conversion factors: update. Ancient TL 29(1), 5-8.

Huntley, D.J., Baril, M.R. (1997). The K content of the K-feldspars being measured in optical dating or in thermoluminescence dating. Ancient TL 15, 11–13.

Kreutzer S, Burow C, Dietze M, Fuchs M, Schmidt C, Fischer M, Friedrich J. (2019). Luminescence: Comprehensive Luminescence Dating Data Analysis. R package version 0.9.5, https://CRAN.R-project.org/package=Luminescence.

Kreutzer S, Schmidt C, Fuchs MC, Dietze M, Fischer M, Fuchs M. (2012). “Introducing an R package for luminescence dating analysis.” Ancient TL 30(1), 1-8.

Prescott, J.R., Hutton, J.T. (1994). Cosmic ray contributions to dose rates for luminescence and ESR dating: large depth and long-term time variations. Radiation Measurements 23, 497-500.

Rees-Jones, J., 1995. Optical dating of young sediments using fine-grain quartz. Ancient TL 13, 9–14.

Richter, D., Richter, A., Dornich, K. (2015). Lexsyg smart — a luminescence detection system for dosimetry, material research and dating application. Geochronometria 42, 202–209.

Tudyka, K., Miłosz, S., Adamiec, G., Bluszcz, A., Poręba, G., Paszkowski, Ł., Kolarczyk, A., 2018. μDose: A compact system for environmental radioactivity and dose rate measurement. Radiation Measurements 118, 8–13.

Tab. 3.4 Regression coefficients and statistics of the correspondence analysis for gastropods and sediment proxies.

Regression coefficients and statistics

Coeff. p

V.pygmaea C_org. 2,7102 0,00042027*** CaCO3 -0,0081459 0,68876 Leitf. -0,00015662 0,47051 Salz_% -0,046366 0,067383 Suszep 0,00099571 0,0047608 Ton -0,012879 0,20575

T.cylindrica C_org. 3,3634 0,01176** CaCO3 0,011616 0,74789

Leitf. -0,00078161 0,045439* Salz_% -0,028941 0,51616 Ton -0,00074228 0,96708 H.selecta C_org. 0,16262 0,055024 CaCO3 0,0031104 0,18212 Leitf. 4,04E-05 0,10533 Salz_% 0,0013348 0,6402 Ton 0,0007105 0,53835 G.interrupta C_org. 10,907 0,6936 CaCO3 -0,25383 0,74057 Leitf. -0,01468 0,075607 Salz_% -0,42638 0,65178 Ton -0,39391 0,30374 Slugs C_org. -0,080752 0,20831 CaCO3 0,0011553 0,51397 Leitf. 1,62E-05 0,38994 Salz_% 0,0015473 0,47812 Ton 0,0012756 0,1502 P.inops C_org. -0,07191 0,82132 CaCO3 -0,005539 0,53045 Leitf. 0,00011163 0,23722 Salz_% 0,010535 0,33375 Ton 0,0031954 0,46751 T.callicratis C_org. 0,58513 0,2556 CaCO3 -0,0056385 0,69124 Leitf. -0,00021012 0,1676 Salz_% -0,0098388 0,57397 Ton -0,00065672 0,92593

C.acicula C_org. 84,091 0,020867** CaCO3 -0,21226 0,83002

Leitf. -0,02462 0,021892** Salz_% -0,99695 0,41415 Ton -0,049952 0,91916 M.pupoides C_org. -16,443 0,093258 CaCO3 0,22314 0,40721 Leitf. -0,0012593 0,66017

Salz_% 0,046705 0,88774 Ton 0,39839 0,0038586***

V.costata Constant 3,2458 0,56712 C_org. 5,2997 0,48562 CaCO3 0,010428 0,96042 Leitf. -0,0028925 0,1992 Salz_% -0,0023392 0,99279 Ton 0,0016175 0,98767 K.crenimargo C_org. -2,7961 0,90686 CaCO3 -0,18973 0,77444 Leitf. -0,011581 0,10392 Salz_% -0,39682 0,62679 Ton -0,26945 0,41466 P._tuberifera C_org. -0,038064 0,96269 CaCO3 0,0045814 0,83895

Leitf. -0,00053168 0,029607** Salz_% -0,013333 0,63141 Ton -0,0037072 0,74122 Vertebrate_remains C_org. -2,8641 0,177 CaCO3 0,066563 0,25637 Leitf. 1,89E-05 0,97575 Salz_% 0,068838 0,34002

Ton 0,075718 0,010948**

G.signata C_org. 130,62 0,025623** CaCO3 -0,17071 0,91459

Leitf. -0,043467 0,012271** Salz_% -1,2868 0,51231 Ton -0,08837 0,91121 P.poltavica C_org. -16,328 0,46484 CaCO3 -0,014839 0,98083 Leitf. -0,0067094 0,30981 Salz_% -0,55564 0,46604 Ton 0,16035 0,60236 P.bipapulata C_org. -0,15898 0,78742 CaCO3 -0,0024351 0,88143 Leitf. -0,00014269 0,41329 Salz_% 0,00058561 0,97677 Ton -0,0057787 0,4779 P.trplicata C_org. 0,76035 0,88985 CaCO3 0,0039518 0,97926 Leitf. -0,002014 0,21647 Salz_% -0,037482 0,84142 Ton -0,065028 0,39159

V.pulchella C_org. 36,261 0,027681** CaCO3 -0,15735 0,7256 Leitf. -0,0093509 0,053423 Salz_% -0,46895 0,39686 Ton -0,015421 0,94489

X.derbentina C_org. 0,32151 0,010833** CaCO3 0,00091325 0,78904

Leitf. -7,24E-05 0,049639** Salz_% -0,0027768 0,5096 Ton -0,00027824 0,86992 C.tridens

C_org. 0,86219 0,36582 CaCO3 -0,005399 0,83755 Leitf. 0,00015115 0,5905 Salz_% -0,0025779 0,93665 Ton 0,017823 0,1768

Tab. 3.5 Palaeo-record of the gastropod species for the section BL.

81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 sample number 196 505 276 12 15 21 18 64 71 2 1 1 1 1 1 1 4 4 3 1 6 1 2 ------Fragments 151 479 248 11 17 18 59 71 2 1 1 1 9 1 1 1 4 2 2 1 5 1 1 ------Est. Number of broken ind. Ceciloides acicula 12 27 1 8 5 6 ------Complete shells 163 506 256 11 17 23 59 77 2 1 1 2 9 1 1 1 4 2 2 1 5 1 1 ------Total 17 18 11 10 11 20 11 10 26 29 7 8 5 8 2 4 1 5 3 1 1 1 1 2 1 1 3 5 1 3 7 5 6 2 4 8 2 6 4 1 1 7 ------Fragments 16 17 4 4 4 4 4 5 2 2 1 2 3 2 1 1 1 3 1 1 1 1 2 3 1 1 7 3 5 1 4 3 6 1 2 3 1 1 3 5 3 5 ------Est. Number of broken ind. Chondrula tridens 1 1 ------Complete shells 16 18 4 5 4 4 4 5 2 2 1 2 3 2 1 1 1 3 1 1 1 1 2 3 1 1 7 3 5 1 4 3 6 1 2 3 1 1 3 5 3 5 ------Total 46 1 1 ------Fragments 39 1 1 ------Est. Number of broken ind. Harmozica selecta 1 ------Complete shells 40 1 1 ------Total 335 141 10 32 10 10 23 10 15 54 12 60 66 42 30 16 3 2 2 2 5 1 1 2 4 5 5 8 4 7 3 1 2 5 5 2 4 6 1 1 1 7 4 2 3 4 1 3 7 4 4 1 4 3 2 2 2 1 1 2 1 3 4 3 2 8 2 1 9 ------Fragments 335 141 10 30 23 10 12 54 11 60 66 38 30 15 1 2 1 2 4 9 1 1 2 1 1 2 4 2 7 3 1 1 1 5 2 3 6 1 1 1 5 1 1 1 1 1 1 3 1 1 1 9 1 1 2 1 1 1 1 1 1 1 4 1 2 7 1 1 7 ------Est. Number of broken ind. Kalitinaia crenimargo 2 7 ------Complete shells 342 141 10 32 23 10 12 54 11 60 66 38 30 15 1 2 1 2 4 9 1 1 2 1 1 2 4 2 7 3 1 1 1 5 2 3 6 1 1 1 5 1 1 1 1 1 1 3 1 1 1 9 1 1 2 1 1 1 1 1 1 1 4 1 2 7 1 1 7 ------Total

------Fragments

------Est. Number of broken ind. Slugs 1 1 4 ------Complete shells 1 1 4 ------Total 694

------Fragments 694

------Est. Number of broken ind. Truncatellina sp. 61 ------Complete shells (*)

------Total

------Fragments

------Est. Number of broken ind. Pupilla inops 3 ------Complete shells 3 +2 ------Total 392 148 20 23 12 42 14 19 31 75 27 60 28 14 4 9 2 4 8 2 1 2 2 1 1 1 3 5 1 1 1 4 6 3 2 1 2 7 6 6 ------Fragments 392 148 20 23 12 42 10 19 31 75 27 60 28 13 4 9 2 4 6 2 1 2 2 1 1 2 5 1 1 1 4 5 3 2 1 2 5 6 6 ------Est. Number of broken ind. Gibbulinopsis interrupta 13 1 3 1 1 1 2 1 1 ------Complete shells 60 13 4 405 148 6 20 26 42 11 19 31 76 28 28 13 4 9 2 4 6 2 1 2 1 2 1 1 1 2 5 1 1 1 4 5 3 +2 1 2 5 +9 +33 6 ------+2 Total 155 192 12 57 11 16 51 58 24 74 1 6 1 3 3 3 1 8 2 ------Fragments 151 192 12 57 11 14 51 58 24 74 1 5 1 2 3 3 1 5 2 ------Est. Number of broken ind. Pupilla poltavica 1 8 2 3 4 5 ------Complete shells 79 65 3 151 192 13 11 14 54 62 24 +162 1 +11 5 1 2 3 3 +2 5 2 ------Total 62 14 ------Fragments 62 14 ------Est. Number of broken ind. Pupilla kyrostriata 11 1 ------Complete shells 15 73 +30 ------Total 550 433 404 1 2 5 5 2 ------Fragments 550 433 404 1 1 5 5 2 ------Est. Number of broken ind. Gibbulinopsis signata 1 2 1 ------Complete shells 434 7 1 550 404 +14 1 1 +1 5 +231 2 ------Total 822 440 82 14 30 19 38 2 1 2 1 5 6 2 1 4 2 4 5 9 ------Fragments 822 320 82 14 30 19 38 2 1 2 1 1 6 2 1 4 2 4 5 9 ------Est. Number of broken ind. Pupilla sp. 1 ------Complete shells (*) (*) 2 1 2 1 1 6 2 1 1 2 ------Total 14 14 13 10 1 1 1 6 8 ------Fragments 1 1 1 6 4 5 8 4 5 ------Est. Number of broken ind. Imparietula. sp.

------Complete shells 1 1 1 6 4 5 8 4 5 ------Total 14 19 1 2 1 4 ------Fragments 14 15 1 2 1 4 ------Est. Number of broken ind. Truncatellina 152 1 1 1 7 1 ------Complete shells cylindrica 156 21 15 1 1 1 3 2 +435 ------Total 290

90 87 Fragments 1 1 5 1 2 2 1 8 1 1 1 1 1 3 1 4 6 3 1 1 3 2 1 ------223

72 63 Est. Number of broken ind. 1 1 5 1 1 2 1 7 1 1 1 1 1 3 1 3 6 3 1 1 3 2 1 ------Vallonia pulchella 25 18 23 1 5 2 2 2 1 4 2 3 ------Complete shells 241 12 97 86 1 1 5 1 1 3 1 3 1 3 1 3 3 2 7 8 6 1 1 3 2 1 ------Total 10 27 3 4 1 1 1 7 ------Fragments 10 27 3 4 1 1 1 7 ------Est. Number of broken ind. Vitrea pygmaea 1 1 1 1 1 2 ------Complete shells 11 29 1 3 5 1 1 2 1 7 ------Total 12 37 25 2 ------Fragments 12 37 21 2 ------Est. Number of broken ind. Xeropicta derbentina

------Complete shells 12 37 21 2 ------Total 10 3 ------Fragments 8 3 ------Est. Number of broken ind. Truncatellina 40 ------Complete shells callicratis 43 +119 8 ------Total 116 126 14 59 15 40 45 88 11 2 4 4 2 4 3 1 3 1 2 1 3 4 8 1 2 3 1 4 1 1 3 ------Fragments 107 45 12 27 39 56 97 2 9 4 3 1 3 2 7 1 2 1 1 1 2 3 7 1 2 3 1 2 1 1 3 ------Est. Number of broken ind. Multidentula pupoides 1 ------Complete shells 107 45 12 27 39 56 97 2 9 4 3 1 3 2 7 1 2 2 1 1 2 3 7 1 2 3 1 2 1 1 3 ------Total 12 3 2 1 ------Fragments 10 2 2 1 ------Est. Number of broken ind. Vallonia costata 10 5 8 ------Complete shells 12 15 10 1 ------Total 1 ------Fragments 1 ------Est. Number of broken ind. Gastropod eggs 14 49 12 1 1 1 ------Complete shells 15 49 12 1 1 1 ------Total 328

------Fragments 264

------Est. Number of broken ind. Gibbulinopsis sp.

------Complete shells (*)

------Total 3 ------Fragments 3 ------Est. Number of broken ind. sp. Aegopinella

------Complete shells 3 ------Total ja ja ja ja ja ja ja ja ja ja ja ja ja ja ja nein nein ja ja

Vertebrate teeth or bones ja ------Beetles ja ja ja ja ja ------Seeds

Tab. 3.6 Palaeo-record of the gastropod species for the section Sevkar. 16 17 10 11 12 13 14 15 18 2 3 4 5 6 7 8 9 sample number 1 6 9 ------Fragments 1 4 8 ------Est. Number of broken ind. Ceciloides acicula 5 ------Complete shells 13 1 4 ------Total 13 7 5 7 2 1 2 5 ------Fragments 11 3 5 4 2 1 2 4 ------Est. Number of broken ind. Chondrula tridens 1 ------Complete shells 11 3 5 4 2 1 2 5 ------Total 11 ------Fragments 6 ------Est. Number of broken ind. Harmozica selecta 1 ------Complete shells 7 ------Total 15 ------Fragments 15 ------Est. Number of broken ind. Hygromiidae sp. 2 ------Complete shells 17 ------Total 123 103 14 26 16 21 43 18 37 10 1 1 1 9 7 5 - Fragments 120 14 23 12 95 20 40 16 27 1 1 1 9 7 4 - - Est. Number of broken ind. Kalitinaia crenimargo 8 ------Complete shells 120 14 23 12 95 20 40 16 27 17 1 1 1 9 7 4 - Total

------Fragments

------Est. Number of broken ind. Slugs 1 ------Complete shells 1 ------Total 3 ------Fragments 3 ------Est. Number of broken ind. Aegopinella sp.

------Complete shells 3 ------Total 11 ------Fragments 8 ------Est. Number of broken ind. Xeropicta derbentina

------Complete shells 8 ------Total 13 1 1 ------Fragments 7 1 1 ------Est. Number of broken ind. Pupilla inops 2 1 2 ------Complete shells 9 2 2 1 ------Total 332 654 171 303 138 164 1 6 7 4 2 3 4 9 8 - - Fragments 222 600 156 373 122 135 1 6 4 4 2 3 4 9 8 - - Est. Number of broken ind. Gibbulinopsis interrupta 1 1 6 5 1 1 ------Complete shells 228 605 156 374 122 136 2 6 4 5 2 3 4 9 8 - - Total 23 46 34 13 29 10 15 8 8 5 ------Fragments 16 46 32 11 27 12 4 7 8 5 ------Est. Number of broken ind. Pupilla aff. poltavica 1 1 2 ------Complete shells 17 46 33 13 27 12 4 7 8 5 ------Total 1 4 5 1 ------Fragments 1 4 3 1 ------Est. Number of broken ind. 1 5 ------Complete shells Pupilla trplicata

Total 2 9 3 1 ------11 4 3 4 7 4 ------Fragments 4 3 4 6 4 4 ------Est. Number of broken ind. sp. Imparietula sp.

------Complete shells 4 3 4 6 4 4 ------Total 113 2 ------Fragments 85 2 ------Est. Number of broken ind. Truncatellina 58 ------Complete shells cylindrica 143 2 ------Total 10 1 6 ------Fragments 10 1 5 ------Est. Number of broken ind. Vallonia pulchella 1 1 5 1 ------Complete shells 10 11 1 2 ------Total 21 ------Fragments 21 ------Est. Number of broken ind. Vitrea pygmaea 9 ------Complete shells 30 ------Total

Tab. 3.7 Gastropod taxa included in the palaeo-record and related ecological information.

Species Ecology Distribution Fossil records

Gibbulinopsis Semideserts and alpine steppes, Caucasian endemic, central and unknown interrupta under xerophilous shrub and eastern part of Ciscaucasia, (Reinhardt in stones, in association with eastern Georgia, large parts of Martens, Paliurus christi and phrygana Armenia and Azerbaijan, 1876) shrub, but also in dry meadows easternmost Turkey and xerophilous forest habitats (Akramowski, 1976, Schileyko, (Akramowski, 1976). 1984, Schütt, 2010).

Gibbulinopsis Semideserts of low and medium Southeast Caucasia towards unknown signata altitudes, phryganoid vegetation Central Asia, China, Afghanistan (Mousson, and sporadically in steppe and and Pakistan (Schileyko, 1984, 1873) xerophilous forests (Akramowski, Pokryszko et al., 2009). 1976)

Pupilla inops Alpine and subalpine zone, Caucasian endemic, eastern unknown (Reinhardt, occasionally also in lower Ciscaucasia and mountainous 1877) altitudes, near rivers, in alpine parts of Ciscaucasia, steppes mainly under thorny widespread in Armenia shrub, stones and overgrown (Schileyko, 1984). gravel, sporadic also in mountain forests (Akramowski, 1976).

Pupilla aff. unknown Only known from Ukraine Exclusively fossil, poltavica (Boettger, 1889). Ukraine loesses (Boettger, (Boettger, 1889) 1889)

Truncatellina Meso-xerophilous habitats like Southern part of western Europe Extremely rare in callicratis sparse forests, xerophilous forbs, and Mediterranean towards deposits from warm (Scacchi, xerophilous forests and Central Asia, absent from glacial phases in 1833) phryganoid vegetation. Turkey, but relatively common in Germany and mountainous parts of the Bohemia Caucasus Region including (Ložek,1964). Armenia (Schileyko, 1984, Welter-Schultes, 2012).

Truncatellina Xerotherm habitats from the Western Europe and Mainly in Central cylindrica lowland to the alpine zone, mainly Mediterranean towards Iran and Europe during warm (Férussac, phrygana, meadow steppe and the southern Ural, abundant in glacial phases 1807) xerophilous forests, occasionally Armenia (Akramowski, 1976, (Ložek,1964). in alpine pastures (Akramowski, Schileyko, 1984, Welter-

1976). Schultes, 2012).

Vallonia Open, mesic, stony grass land, Western Palaearctic eastwards Very abundant in costata alpine meadows, shrub of to Lake Baikal and eastern Central Europe (Müller, 1774) phrygana, in the Caucasus also in North America (Gerber, 1996) during warm glacial xerophilous forests and bushland phases and cold (Akramowski, 1976). interglacial phases, also in loess

(Gerber, 1996, Ložek,1964)

Vallonia In meadows of different types, Entire Palaearctic and eastern Oldest records from pulchella usually at humid localities, but North America (Gerber, 1996). the Upper Pliocene, (Müller, 1774) occasionally also in dry meadows, very abundant in rarely found in open forests, in the Central Europe Caucasus mainly in alpine and during interstadials, subalpine pastures (Akramowski, (Gerber, 1996, 1976, Gerber, 1996, Schileyko, Ložek,1964), 1984). Caucasian fossil records from the Early Pleistocene of Dmanisi in Georgia (Gerber, 1996).

Chondrula Open, relatively dry pastures, Western Europe to northern Iran Abundant in tridens (Müller, shortgrass at xerophilous (Welter-Schultes, 2012, Bank & Quaternary deposits 1774) calcareous slopes, forest margins, Neubert 2017), very common in (Ložek,1964). occasionally in open xerophilous steppe areas of Ukraine and the forests (Akramowski, 1976). Caucasia, including Armenia.

Multidentula Typically found in steppes, but Caucasian endemic, Upper Pliocene pupoides also phryganoid vegetation Ciscaucasia to the northernmost Caucasian (Krynicki, (Akramowski, 1976), dry open or parts of Iran (Schileyko, 1984, desposits (Steklov, 1833) bushy habitats mostly beneath Bank & Neubert, 2016). 1966). stones and in subalpine meadows.

Cecilioides Blind, subterranean, Western Europa and Upper Pleistocene acicula thermophilous species living in Mediterranean towards Central and numerous (Müller, 1774) loose, well developed soils under Asia (Welter-Schultes, 2012). In Holocene deposits dry open places (e.g. xerophilous Armenia widespread, but (Danukalova et al., forests, forest steppe, meadows relatively rare. 2015, Ložek,1964). and grass steppe) (Akramowski, 1976, Menez 2001)

Vitrea Sparse dry forests with Quercus, Southeastern Europe and Chinese loess (Wu pygmaea Juniperus and shrub but, Crimea to northern Iraq and et al., 2000). (Boettger, occasionally in open grassland, Turkmenistan (Pintér, 1972, 1880) often associated with Palliurus Riedel, 1962, 1966, 1995). christi and raspberry, in leaf litter Abundant in Armenia where it and under stones, preverably lives lives at up to 1500 m a.s.l. in dry forest habitats (Riedel, (Akramowski, 1976). 1966).

Kalitinaia Mainly in Artemisia semidesert, Caucasian endemic, Caucasian records crenimargo phryganoid shrub, but also on Ciscaucasia, eastern Georgia, from Pliocene of (Pfeiffer, 1848) subalpine gravel steppe up to most parts of Azerbaijan and Ingushetia (Steklov, 2000 m.a.s.l., sporadically in dry Armenia (Akramowski, 1976, 1966). habitats in clearings of Schileyko, 1978) xerophilous forests, hibernates in

the ground at roots of shrub or under stones (Akramowski, 1976)

Xeropicta Dry habitats with periodic Native to Turkey, Crimea and Fossil records from derbentina precipitation and a warm climate the Caucasus region, introduced Azerbaijan (Krynicki, (usually in low altitudes), clearings to several European countries (Bogatshev, 1936) 1836) of xerophilous forests and forest (De Mattia, 2007, De Mattia & steppes, lives in association with Pešić 2014, Schileyko, 1978). In Palliurus christi, hibernation under Armenia the most abundant stones and roots (Akramowski, snail in urban wasteland 1976).

Stenomphalia Dry open habitats from low Caucasian endemic, abundant Unknown selecta (Klika, altitudes to the subalpine zone, in in Georgia and northern 1894) grass and under stones (Egorov, Armenia where it lives in up to 2008), open forests, meadows, 2700 m a.s.l., also in pastures, gardens, xerothermous Ciascaucasia and easternmost slopes. Turkey (Akramowski, 1976, Schileyko, 1978, Schütt, 2010).

References:

Akramowski, N. N. (1976). Mollyuski. Fauna Armyanskoi SSR. Yerevan.

Bank, R. A. and E. Neubert (2016). Notes on Enidae, 7. Revision of the Enidae of Iran, with special reference to the collection of Jacques de Morgan (Gastropoda: Pulmonata). Vita Malacologica 14: 1-84.

Boettger, O. (1889). Die Entwicklung der Pupa-Arten des Mittelrheingebietes in Zeit und Raum. Jahrbücher

96 des Nassauischen Vereins für Naturkunde 42: 225-327, pl. 6-7.

Bogatschev, V. V. (1936). Presnovodnye i nazemnye molljuski iz verehnetretitschnych otlozenij assejna reki

Kury. Trudy azerbajdzanskovo f ilia1a Akad . Nauk SSSR, geol . Ser. 13: 5-99, pl. 91-10.

Cameron, R. A. D., et al. (2013). Forest snail faunas from Crimea (Ukraine), an isolated and incomplete

Pleistocene refugium. Biological Journal of the Linnean Society 109: 424-433

De Mattia, W. (2007). Xeropicta derbentina (Krynicky, 1836) (Gastropoda, Hygromiidae) in Italy and along the

Croatian coast, with notes on its systematics and nomenclature. Basteria 71: 1-12.

De Mattia, W. and V. Pešić (2014). Xeropicta (Gastropoda, Hygromiidae) goes west: the first record of X. krynickii (Krynicki, 1833) for Montenegro, with a description of its shell and genital morphology, and an additional record of X. derbentina (Krynicki, 1836) for Italy. Ecologica Montenegrina 1(4): 193-200.

Gerber, J. (1996). Revision der Gattung Vallonia Risso 1826 (Mollusca: Gastropoda: Valloniidae). Schriften zur

Malakozoologie 8: 1-227.

Menez, A. (2001). Some notes on Cecilioides acicula (Ferussaciidae) from South Iberia. Journal of Conchology

37(2): 231.

Pintér, L. (1972). Die Gattung Vitrea Fitzinger 1833 in den Balkanländern (Gastropoda: Zonitidae). Annales

Zoologici, Warszawa 29(8): 209-315.

Pokryszko, B. M., et al. (2009). Pupilloidea of Pakistan (Gastropoda: Pulmonata): Truncatellininae,

Vertigininae, Gastrocoptinae, Pupillinae (in part). Annales Zoologici, Warszawa 69(4): 422-458.

Riedel, A. (1962). Materialien zur Kenntnis der Zonitidae (Gastropoda) des Nahen Ostens, nebst Beschreibung der Gattung Eopolita Poll. im breiteren geographischen Rahmen. Annales Zoologici, Warszawa 20(15): 261-

298.

Riedel, A. (1966). Zonitidae (excl. Daudebardiinae) der Kaukasusländer (Gastropoda). Annales Zoologici,

Warszawa 24(1): 1-303.

Riedel, A. (1995). Zonitidae sensu lato (Gastropoda, Stylommatophora) der Türkei. Übersicht der Arten.

Fragmenta Faunistica 38(1): 1-85.

Schileyko, A. A. (1978). Nazemnyje molljuszki nadszemejsztva Helicoidea [Fauna UdSSR. Mollusca III, 6.

Landmollusks of the subfamily Helicoidea]. Leningrad.

Schileyko, A. A. (1984). Nazemnyje molljuszki podotrjada Pupillina fauny SSSR (Gastropoda, Pulmonata,

Geophila). Leningrad.

Schütt, H. (2010). Turkish Land Snails. 5th, revised edition. Solingen, Verlag Natur und Wissenschaft.

Steklov, A. A. (1966). [Terrestrial Neogene mollusks of Ciscaucasia and their stratigraphic importance].

Moscow, Nauka.

Welter-Schultes, F. W. (2012). European non-marine molluscs, a guide for species identification. Göttingen,

Planet Poster Editions.

Wu, N., Rousseau, D. D., & Liu, X. (2000). Response of mollusk assemblages from the Luochuan loess section

to orbital forcing since the last 250 ka. Chinese Science Bulletin, 45(17), 1617-1622.

Tab. 3.8 Checklist of the shelled terrestrial molluscs of Tavush based on a literature survey, own collections and museum material.

Gastropod species

TAVUSH Pomatias r. rivularis (Eichwald, 1829) X Carychium minimum Müller, 1774 X Carychium tridentatum (Risso, 1826) X Oxyloma elegans (Risso, 1826) X Succinea putris (Linnaeus, 1758) X Succinella oblonga (Draparnaud, 1801) X Cochlicopa lubrica (Müller, 1774 X

Cochlicopa lubricella (Rossmässler, 1834) X Pupilla interrupta (Reinhardt, 1876) X Pupilla signata (Mousson, 1873) X Pupilla kyrostriata Walther & Hausdorf, 2014 X Pupilla triplicata (Studer, 1820) X Chondrina arcadica (Reinhardt, 1881) X Granopupa granum (Draparnaud, 1801) X Lauria cylindracea (Da Costa, 1778) X Sphyradium doliolum (Bruguière, 1792) X Pyramidula pusilla (Vallot, 1801) X Acanthinula aculeata (Müller, 1774) X Vallonia costata (Müller, 1774) X Vallonia pulchella (Müller, 1774) X Columella edentula (Draparnaud, 1805) X Truncatellina callicratis (Scacchi, 1833) X Truncatellina costulata (Nilsson, 1823) X Truncatellina cylindrica (Férussac, 1807) X Vertigo pygmaea (Draparnaud, 1801) X Vertigo nitidula (Mousson, 1876) X Vertigo pusilla Müller, 1774 X Multidentula pupoides (Krynicki, 1833) X Chondrula tridens (Müller, 1774) X Georginapaeus hohenackeri (Pfeiffer, 1848) X Anatolya brevior (Mousson, 1876) X Pseudochondrula tetrodon (Mortillet, 1854) X Merdigera obscura (Müller, 1774) X Armenica likharevi Nordsieck, 1975 X Armenica unicristata (Boettger, 1877) X Elia ossetica (Mousson, 1863) X Mentissoidea rupicola (Mortillet, 1854) X Scrobifera taurica (Pfeiffer, 1848) X Mucronaria duboisi (Charpentier, 1852) X Quadriplicata quadriplicata (Schmidt, 1868) X Caspiophaedusa p. perlucens (Boettger, 1877) X Cecilioides acicula (Müller, 1774) X Punctum pygmaeum (Draparnaud, 1801) X Discus ruderatus (Hartmann, 1821) X Zonitoides nitidus (Müller, 1774) X Euconulus fulvus (Müller, 1774) X

Conulopolita retowskii (Lindholm, 1914) X Eopolita derbentina (Boettger, 1886) X Oxychilus koutaisanus (Mousson, 1863) X Oxychilus emmae (Akramowski, 1955) X Oxychilus subeffusus (Boettger, 1879) X Aegopinella pura (Alder, 1830) X Nesovitrea petronella (Pfeiffer, 1853) X Vitrea pygmaea (Boettger, 1880) X Oligolimax annularis (Studer, 1820) X Vitrina pellucida (Müller, 1774) X Caucasotachea a. calligera X (Dubois de Montpéreux, 1840) Helix buchii Dubois de Montpéreux, 1839 X Helix lucorum Linnaeus, 1758 X Helix vulgaris Rossmässler, 1839 X Kalitinaia crenimargo (Pfeiffer, 1848) X Xeropicta derbentina (Krynicki, 1836) X Fruticocampylaea narzanensis (Krynicki, 1836) X Diplobursa pisiformis pisiformis (Pfeiffer, 1846) X Harmozica ravergiensis (Férussac, 1835) X Karabaghia bituberosa (Lindholm, 1927) X Stenomphalia selecta (Klika, 1894) X

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4 MALACOLOGICAL INVESTIGATIONS ON EASTERN CANARY SEDIMENT ARCHIVES – STABLE ISOTOPE INTERPRETATION IN AN OZEANIC SETTING

Chapter 4 is submitted to the peer-reviewed Journal of Quaternary Science as:

CLIMATE SHIFTS VS. EDAPHIC HUMIDITY AND THE DIFFICULTY OF PALAEORECONSTRUCTIONS - A MALACOLOGICAL STUDY ON STABLE ISOTOPES IN DUNE SEQUENCES OF FUERTEVENTURA

Authors: Christiane Richter1, Christopher-Bastian Roettig1, Daniel Wolf1, Thomas Kolb², Dominik Faust1

1Dresden University of Technology, Helmholtzstraße 10, 01069 Dresden 3 Justus-Liebig-University Giessen, Senckenbergstr. 1, 35390 Gießen

Publication history: submitted: July 2020

Abstract. Dune-palaeosurface sequences on the Eastern Canary Islands were investigated for stable isotope records in gastropod shells of the genus Theba. Due to the ecology of the taxon and the special oceanic insularity of the study site, we assume that δ18O signals in our case mainly reflect shifts in δ18O signals of sea surface water. We found that a rapid decrease in δ18O signals indicating marine transgressions is associated with significant changes in the gastropod associations. We suppose that these faunal changes were caused by strong (hot) winds at the end of glacial periods that were discovered by Moreno et al. (2001). In addition, we assume that rapid decreases in δ18O shell are followed by geomorphologically stable phases due to marine transgressions, leading to dust preservation that dominates the palaeosurface characteristics. These palaeosurfaces correlate with maxima in biodiversity of the gastropods as well as more negative δ13C signals, which indicate a higher proportion of C3 plants. Based on our results, we suggest the silty palaeosurfaces to be related to enhanced soil moisture conditions due to higher water storage capacity in the finer substrate independent of climatic humidity conditions.

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4.1 INTRODUCTION

The Quaternary period is characterised by strong climatic fluctuations, which significantly influence the morphology of our geosphere and biosphere. In order to better understand the cause-effect relationships of changing environmental factors and the resulting earth-surface processes, it is indispensable to investigate sediment-archives of different kind and in different settings. In this context, dune palaeosurface sequences on the Canary Islands are ideally suited for investigating landscape evolution against the background of climate changes, sea- level fluctuations, wind system modifications, and various other more site-specific parameters. As these deposits are rich in biogenic fossils, we use Quaternary gastropods as environmental proxies. Dune sequences on the Eastern Canary Islands have been studied inter alia by Meco & Pomel (1985), Rognon et al. (1989), Damnati et al. (1996), Bouab & Lamothe (1997), Coello et al. (1999), Ortiz et al. (2006), Suchodoletz et al. (2009), Faust et al. (2015) and Roettig et al. (2020). In aeolianit-palaeosol sequences of higher latitudes, palaeosols are generally a product of mineral weathering and neo-formation under more humid environmental conditions in interglacial (interstadial) phases caused by higher temperatures and rainfall. In contrast, Roettig et al. (2019) suggest that dune-palaeosol sequences on Fuerteventura are built up by different dune generations intercalated by palaeosurfaces. They found that formerly assumed “palaeosols” on the Canary Islands are not predominantly formed by pedogenetic processes since no distinct indications for real in-situ pedogenesis could be found. Rather, respective reddish silty layers were linked to palaeosurfaces formed during phases of interrupted sand supply and predominant deposition and preservation of Saharan dust that proceeded more or less independent from local climate conditions. Therefore, a major aim of this study is, to investigate the significance of local climate on palaeosurface formation on Fuerteventura and to apply additional independent proxies to verify the hypothesis of Roettig et al. (2019). Richter et al. (2019) found increased biodiversity of snails related to paleosurfaces as well as species that indicate a more pronounced plant cover. We aim to characterise in more detail the crucial factors that trigger these more diverse ecosystems associated to paleosurfaces. In particular, we want to find out whether a higher ambient humidity played a role, either in the form of climatic humidity or by an increase in edaphic humidity due to altered substrate properties, as suggested by Richter et al. (2019) (also see Jahn, 2010 and Roettig et al., 2019). In this context, stable isotope analyses of δ13C and δ18O on gastropod shells are particularly suitable to distinguish between climatic moisture and edaphic moisture. Stable isotope signals of land snail shells are the result of several fractionation processes related to snail metabolism and are influenced by the isotope signals of the ingested resources (water, plants, etc.) and prevalent environmental conditions. Stable isotope signals and related processes in land snail shells have been investigated inter alia by Yapp (1979), Magaritz & Heller (1983), Goodfriend

102

& Hood (1983), Lécolle (1985), Goodfriend et al. (1989), Goodfriend (1992); Stott (2002), Balakrishnan & Yapp (2004) and Yanes et al. (2011, 2013). Yanes et al. (e.g. 2008) contributed fundamental studies to stable isotopes on the Canary Islands. However, this is the first study for the eastern Canary Islands in which information on snail communities and isotope signatures are considered over a period of about 400.000 years. By a lithological unit wise sampling technique within the same test site, features of sandy layers and paleosurfaces can be determined over a period comprising at least the last three glacial-interglacial cycles. This study combines lithostratigraphy with geochemical, biostratigraphic and ecostratigraphic methods. In this way, we gained new insights into Pleistocene environmental conditions on the eastern Canary Islands and processes involved in the formation of dune-palaeosurface sequences. The central questions are: 1) Do we find fluctuations of the δ13C and δ18O isotope signals over time and is it possible to derive climatic or environmental information from these signals? 2) Do δ13C and δ18O signals relate to phases of surface stability in comparison with aeolian deposition? 3a) Which palaeoenvironmental conditions were associated with the formation of palaeosurfaces on the eastern Canary Islands and what were the driving factors? 3b) Is palaeosurface formation on Fuerteventura caused by local climatic influences or by other sedimentary cycles, possibly triggered by global climate shifts?

4.2 GEOGRAPHICAL SETTING AND STATE OF KNOWLEDGE

The study area is located in the northern part of Fuerteventura, which belongs to the easternmost islands of the Canarian archipelago. The studied sequence Encantado (28.63915° N/13.978792° W) is the section, which was best preserved and therefore especially suitable for detailed analyses. Encantado is located southwest of Lajares at the Barranco Encantado (Fig. 4.1). An overview of the lithological units is given in Fig. 4.2, while a detailed lithological description can be found in Roettig et al. (2017).

The modern climate of Fuerteventura is part of the subtropical desert zone (see Peel et al., 2007). Surface runoff and streams are episodic and the annual precipitation is less than 200 mm. The main source of precipitation relates to orographic moisture supplied by north-easterly trade winds, although the low altitudes of the eastern Canary Islands virtually prevent rainfall events (Juan et al., 2000).

Lithological background

Quaternary sediments on Fuerteventura consist largely of aeolian dune sands that were relocated from the shelf during periods of marine regressions. They are predominantly composed of marine bioclastic carbonates (Roettig et al., 2017). These sands are occasionally

103 mixed with different proportions of Saharan dust (Schneider et al., 2020), which is primarily transported by Calima events (Criado and Dorta, 2003, Suchodoletz et al., 2009, Criado et al., 2011, Muhs, 2013). Roettig et al. (2019) relate the formation of silty paleosurfaces with phases of reduced sand supply coinciding with significant marine transgressions. The Quaternary dune and dust deposits partly contain volcanic fallout deposits (lapilli and tephra) or coarse components from reworked basaltic bedrock or caliches (carbonated crusts). During the final

Fig. 4.1 (a) Topographic map of the Canary Islands (Source: modified from stepmap.de), (b) The study area southwest of Lajares with the black arrow indicating the study site (c) The studied outcrop “Encantado” marked by the black arrow (Source: modified from maps.google.de).

104 stages of surface stability, the deposits partially underwent multiple erosion and reworking. In modern times, numerous gullies of barranco and wadi systems deeply dissected the aeolianite sequences, allowing a far-reaching lateral tracking of lithological units along the gully walls.

Fig. 4.2 The section Encantado subdivided into lithological units (according to Roettig et al., 2017 and 2020, modified). All ages are based on infrared stimulated luminescence dating (IRSL), the italic written age was performed on palaeosurface material.

105

Tab. 4.1: Description of the lithological units of section Encantado. Sub units a-e indicate the succession of lithofacies types from the bottom to the top of the referring units.

Lithological Sub-unit Description . unit

Unit 1 sallow greyish-brown strongly loamy sand; contains basalt debris. lapilli. gastropod shells and insect nests

Unit 2 reddish-brown silty to slightly loamy sand; contains lapilli. gastropod shells and insect nests

Unit 3 ochre coloured silty sand; contains lapilli. gastropod shells and insect nests

Unit 4 greyish-ochre coloured sand; enriched with carbonate cement; contains highly concentrated carbonatically cemented insect nests

Unit 5 b light ochre coloured sand; contains lapilli. gastropod shells and insect nests

a sallow ochre coloured silty sand; contains lapilli. gastropod shells and insect nests

Unit 6 b ochre-brown to pinkish coloured silty. slightly loamy sand with volcanic imprint; more loamy to the top; carbonate gravel at the base; basalt debris in top; contains lapilli. gastropod shells and insect nests

a greyish-brown slightly loamy sand; contains lapilli and highly concentrated cemented insect nests

Unit 7 c sallow ochre-brown slightly loamy sand; strongly loamy and dark-brown to the top; contains root-shaped clay cutans and gypsum concretions as well as coated gastropod shells and insect nests

b pinkish ochre-grey coloured slightly loamy sand with volcanic imprint; shows greasing effect; contains many gastropod shells and insect nests

a whitish-ochre coloured sand; contains few biogenic fragments and many crotovines with material from Unit 7b

Unit 8 c light pink coloured loamy sand with volcanic imprint; more loamy to the top; shows greasing effect; contains lapilli. partly coated gastropod shells and insect nests; bioturbation at the top

b reddish-ochre coloured sand; contains few gastropod shells and many crotovines

a light ochre coloured sand; contains few gastropod fragments

Unit 9 ochre-brown slightly loamy sand; strong reddish-brown and more loamy to the top; contains lapilli. gastropod shells and insect nests; bioturbation at the top

Unit 10 ochre-yellow sand with a strong reddish-brown colour and sub-polyedric structure at the top; contains lapilli. gastropod shells and insect nests; crotovines

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Unit 11 greyish-brown coloured loamy sand; strong brown and more loamy to the top; contains lapilli. gastropod shells and insect nests; top contains basalt debris and shows bioturbation

Unit 12 e ochre-brown to pinkish coloured sand with volcanic imprint; contains lapilli. gastropod shells and carbonatically cemented insect nests

d ochre-brown coloured. slightly loamy sand; more loamy to the top; contains lapilli. coated gastropod shells and insect nests

c sallow greyish ochre-brown to pinkish coloured substrate with volcanic imprint; contains lapilli. gastropod shells and coated insect nests

b ochre-brown coloured slightly loamy sand; contains lapilli as well as coated gastropod shells and insect nests

a light ochre coloured sand. slightly loamy to the top; contains layered enrichments of lapilli and gastropod shells. as well as insect nests; bioturbation at the top

Unit 13 dark-brown slightly loamy sand; more loamy and reddish brown to the top; contains gypsum concretions. coated gastropod shells and insect nests; bioturbation at the top

Stable oxygen isotopes

Stable isotope signals in gastropod shells provide information about environmental influences

Fig. 4.3 Variables influencing the δ18O signals of land snail shells (according to Siegenthaler (1979) and Schmidt et al. (1999), modified).

107 during the time of shell carbonate precipitation. Since carbonate precipitation occurs mainly during phases of snail activity (Goodfriend et al., 1989) the recorded environmental influences correspond to certain daytimes and seasons, which are dependent on the species-specific behaviour of the gastropods. The influences on these stable isotope signals are complex. However, many publications show a correlation between δ18O signals in snail shells and mean annual δ18O signals of local precipitation (e.g., Lécolle, 1985; Zanchetta et al., 2005; Kehrwald et al., 2010; Colonese et al., 2014; Prendergast et al., 2015). Local precipitation in turn is a function of the source effect, temperature effect, continentality/rainout effect, altitudinal effect and amount effect (see i.a. Moreno et al., 2014). Furthermore, the global and local circulation of air masses is subject to seasonal and daily fluctuations and was most likely also different for glacial and interglacial periods as well as stadial and interstadial phases.

Despite the strong dependence of δ18O in snail shells on the local precipitation signal, the overprinting of the signal by evaporation processes can also be very strong, affecting both the absorbed precipitation as well as the metabolism and transpiration of the snail itself (see Goodfriend & Magaritz, 1987). Evaporation processes are mainly dependent on aridity/relative humidity, wind movement and temperature and thus differ depending on the local climate (see e.g., Yapp, 1979). In addition, these evaporation processes can vary daily and seasonally (see Magaritz & Heller, 1983).

18 The most important factors that influence the δ O signal in snail shells are illustrated in Fig. 3.

18 (The respired gases O2 and CO2 seemingly do not affect the δ O signals of shells. They are essential for the oxidation of glucose and thus for the generation of energy in the mitochondria, but apparently do not get incorporated in the shell aragonite of terrestrial gastropods (also see Balkarishnan & Yapp, 2004). Similiarly, oxygen from ingested food and the ground does not seem to significantly affect the δ18O shell signals from Theba (see Yanes et al., 2011; comp. Zhang et al., 2018). We for now neglect these factors in the following approach). However, it is also important to consider species-specific differences. Different metabolisms, microhabitats

18 18 and behaviour bias the δ Oshell signal. Thus, δ Oshell records the activity periods of the snail species, which as in continental climate can have two periods of rest, while in tropical climates they can last year-round. On Fuerteventura, the species of the genus Theba keep one aestivation period during the driest and hottest summer months (see McQuad et al., 1979).

For the interpretation of δ18O signals in snail shells across time, we also have to consider that influencing variables presumably fluctuated between glacial and interglacial as well as stadial and interstadial periods. Thus, there is a bias e.g., by differences in the altitude effect and continental effect due to sea level high and low stands, the amount effect, in sea surface temperatures and in evaporation rates due to different relative humidities etc.

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Stable carbon isotopes

The interpretation of δ13C signals in land snail shells allow us to reconstruct the prevalent palaeovegetation via indirect conclusions on ingested food. However, for the interpretation of the signals, it is important to consider all carbon sources for the shell composition and individual nutritional preferences of the respective species. Current studies show that δ13C signals from shell aragonite of terrestrial gastropods are primarily a function of the isotope signals of snail nutrition (Stott 2002, Liu et al. 2007, McConnaughey & Gillikin 2008, Yanes et al. 2013). If the food spectrum of a snail species is known, the δ13C signal can potentially be used to derive the palaeovegetation from the incorporated 13C to 12C ratio in the snail shell. In

13 the case of some Helicids, the δ Cshell signals allow us to derive the proportion of ingested highly xerophilous plant species (C4 and CAM) compared to less xerophilous to mesophilous plant species (C3) (Goodfriend & Magaritz, 1987, Goodfriend, 1990) and therefore can indicate humidity conditions (see Goodfriend, 1990; Prendergast 2015). This principle is based on the different metabolic mechanisms of these plant groups, which cause the incorporation of

13 13 different δ C signals in the respective plant species. Hence, the δ Cplant signal is an indicator of long-term water use efficiency in plants (Ehleringer, 1989; Marshall et al., 2007). On the Canary Islands, Yanes et al. (2008, 2013) investigated δ13C signals in land snail shells of the genus Theba. Therefore, they also measured δ13C signals of C3, C4 and CAM plants at the

13 Eastern Canary Islands and obtained values between -29.0 and -13.0‰, while related δ Cshell signals of Theba geminata from the same localities showed values between -10.1 to 1.7‰ (Yanes et al., 2008, 2013). The most positive δ13C signals of the shells were attributed to a diet based on C4 plants. As many gastropod species are specialised to feed only on a specific group of plants, algae or fungi et cetera. Yanes et al. (2008 and 2013) investigated the nutritional preferences of Theba. They found that Theba geminata feeds on C4, C3 and CAM plants without preferences for a particular group and that the δ13C signals of snail body tissues reflected the ingested plant types in their quantitative spatial distribution at the snail habitat. They also found that δ13C signals of the soft body were positively correlated with δ13C shell signals (Yanes et al., 2013).

Biostratigraphic background

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Richter et al. (2019) examined species compositions on Fuerteventura over the last ca. 360 ka and found that the gastropod associations changed fundamentally. Based on the occurrence of specific communities, they derived eight different biozones (malacozones) (Fig. 4.4). As can be seen in Fig. 4.4, the genus Theba is very robust and continuously occurs throughout the profile. This makes Theba particularly suitable for stable isotope analyses, because of the continuous occurrence on the one hand and the numerous already existing isotope investigations for representatives of this genus on the other. (Theba spp. in this study refers to a species complex that includes Theba arinagae, Theba geminata and probably two new species of the genus (see Richter et al., 2019) - due to their similar ecological behaviour we assume that these different species perform comparable fractionation processes)

Fig. 4.4 Mollusc diagram for the section Encantado, with subdivision into malacozones and line plots of Shannon biodiversity index and total abundances for each sample (from Richter et al., 2019).

4.3 METHODS

Raman spectroscopy and XRD analysis

The mineralogical composition of empty shells of two modern Theba individuals, as well as from samples E-8 and E-1 (four shells of each sample) was analysed via Raman spectroscopy.

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Three to six measurements were performed on different, randomly selected regions of each shell. All analyses were done using a Bruker Senterra R200-L Raman spectrometer working with a 785 nm laser at 100% of 100 mW power. Further analytical parameters were chosen as follows: a 20× objective (NA = 0.4, wd =1.3 mm), a slit of 25×1000 µm, an integration time of 5 s and 12 co-additions, and a spectral range of 60 to 1520 cm-1. An Olympus BX51 confocal microscope was coupled to the Raman spectroscope. Calibration of the system was done against the 520.4 cm-1 line of a silicon standard target. Results are compared with data of aragonite (R040078, R060195, R150021) and calcite (R040070, R040170, R050009, R050048, R050127, R050130, R050307, R150020, R150075) that were analysed at 780 to 785 nm and published in the RRUFF database (Lafuente et al., 2015).

To obtain an independent control of the Raman spectroscopic results, one complete Theba shell of each sample E-8 and -1 were cleaned as described above, pulverised in an agate mortar and analysed via XRD (Bruker D2 Phaser with a Cu anode operating at 30 kV, 10 mA). Parameters of the analyses were a 2θ range of 5.002° to 66.976°, a step size of 0.010° and a counting time of 0.2 s per step.

Stable isotope analysis

From the section Encantado, which is described in the previous chapter and in Roettig et al. (2017), we took 26 sediment samples over a thickness of 15 meters analogous to lithological units as shown in Figs. 5 and 7. From these, we extracted 4 complete adult shells with a similar number of 4 to 4½ whorls per sample for isotope measurements. We analysed exclusively shells of the genus Theba, to minimise taxon-specific differences in metabolic fractionation processes. Furthermore, we analysed stable isotope signals of four modern Theba shells. Since recent environmental conditions apparently do not enable gastropods to live at the immediate profile locations, the modern empty Theba shells were sampled beneath rotten plant material from a valley floor close to the study site. All shells were broken and cleaned in an ultrasonic bath, while adhering loamy or carbonatic accretions were removed with a brush and sand paper also at the internal surface of the shells. Subsequently, shells were air dried and grinded with a porcelain pestle. Measurement, calculation and corrections were conducted by an external laboratory (Prof. Dr. Joachimski, Geozentrum Nordbayern). Therefore, 0.3 mg of the homogenised carbonate powders were merged with 100% phosphoric acid at 70 °C using a Gasbench II connected to a ThermoFisher Delta V Plus mass spectrometer. Results are indicated as delta notation. All values were set in relation to the common standard for carbonates V-PDB (Vienna - Pee Dee Belemnite). Furthermore, reproducibility and accuracy were monitored by replicate analysis of laboratory standards calibrated to international standards NBS 19, NBS 18 and LSVEC. Calcite oxygen isotope values were corrected for aragonite using the phosphoric acid fractionation factors given by Rosenbaum and Sheppard

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(1986) and Kim et al. (2007). The analytical precision of the two laboratory internal standards that were applied, was 0.08‰ and 0.04‰ for δ13C and 0.08‰ and 0.06‰ for δ18O.

Biodiversity-index

The Shannon Index (1948) is used to quantify biodiversity. This index is open upwards and inclines with increasing species richness and equitability, respectively. Equitability describes whether all species are present with similar abundances and indicates if a biotope is stable or rather unstable, and dominated by certain stress factors (see Magurran, 1988). The Shannon biodiversity index was calculated as demonstrated in Shannon (1948).

4.4 RESULTS

Stable isotope analysis

The stable isotope signals for δ13C and δ18O of the Encantado section (supplementary material Tabs. S1 and S2) are plotted in Figs. 5 and 7. The average precision of the sample measurements was 1.22‰ for δ13C and 0.48‰ for δ18O.

As the number of samples is at the lower end of the usual sample quantities used (compared e.g., to Colonese et al. (2011) who measured 3 to 6 shells per lithological unit or Yanes et al. (2013) who measured 4 to 10 shells per lithological unit), we assume less representative medians for datasets with a high variability. δ13C signals for Encantado vary between -6.95‰ and 1.46‰. There is a significant difference between δ13C medians of samples from palaeosurfaces (-5.90‰) compared to all other samples of the profile (-4.71‰) (Kruskal- Wallis test: p=0.002). Accordingly, samples of palaeosurfaces (samples E-10, E-12, E-19, E- 20, E-25 and E-26) are characterised by more negative δ13C signals. In addition, the samples of tephric layers (E-3, E-5, E-14, E-15, E-17, and E-23) show more negative δ13C signals compared to the surrounding layers. Accordingly, the differences between δ13C medians of these tephra-rich samples and the mean of the δ13C medians of the underlying and overlying samples averages -0.6‰ (calculated as follows:

( �� + ��)⁄ �� = �� − 2 x.. Sample x

k.. Sample superjacent to sample x

l.. Sample subjacent to sample x ).

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13 Fig. 4.5 Scatter plot with the δ Cshell signals of fossil shells of the Encantado section and modern snail shells (collected at a comparatively moist valley floor close by) and calculated median values of 13 these δ Cshell signals are plotted with gastropod biodiversity proxies (species richness (purple) and Shannon index (green)).

13 In comparison, these differences in δ Cshell signals compared to the surrounding substrate are -1.1‰ for palaeosurfaces and 0.8‰ for all other samples in average (see Fig. 6). This

13 shows, that tephric samples have significantly more negative δ Cshell values compared to the surrounding substrate than all other samples that are neither tephras nor palaeosurfaces ((Kruskal-Wallis test: p=0.015, Fig. 6).

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Fig. 4.6 The boxplot depicts the difference 18 between median δ Oshell for a specific sample 18 position and the average of the median δ Oshell signals for the adjacent sample positions of the surrounding sediment. All differences are sorted by lithofacies types that are tephric layers, palaeosurfaces and other facies (mainly sandy layers).

If we exclude the samples with the largest standard deviations (above 2‰) that are

13 samples E-3, E-7, E-8 and E-17, we can detect an inverse correlation between δ Cshell and the Shannon index (taken from Richter et al., 2019). The corresponding correlation factor after Pearson is -0.49 with a level of significance of p=0.034, which corresponds to a residual risk of 3.4% for the relation to be random.

18 13 δ Oshell signals vary between -1.49 and 2.26‰, and do not correlate with δ Cshell or

18 any other proxy of the malacological analyses. δ Oshell values are particularly high for samples E-4, E-7, E-10, E-16, E-18, E-20, E-22, E-25 and E-27 showing no continuous pattern related to palaeosurfaces.

Modern shells in this study showed δ18O values between -0.55 and -0.93‰, which are more negative compared to the uppermost part of the Encantado profile (sample E-27).

18 Sample E-27 is characterised by a median δ Oshell signal of 1.23‰ and due to its allocation to lithological units 1-3, presumed to correspond to an age of around 16 ka before present (Roettig et al., 2017).

Mineralogical analysis

Mineralogical analyses applying Raman spectroscopy on two shells of modern Theba and samples E-8 and E-1 (four specimens each) yielded almost pristine aragonite on 34 of 39 spots (supplementary material Fig. S1). The patterns of the remaining five measurements, i.e., three on one shell of sample E-8 and two on one shell of sample E-1, gave reason to assume subordinate presence of calcite. Both XRD analyses on complete shells of E-8 and E-1 showed patterns indicative for the presence of pure aragonite (supplementary material Fig. S1).

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Fig. 4.7 Scatter plot with the δ18O signals of the fossil gastropod shells of the Encantado section and modern snail shells (collected at a comparatively moist valley floor close by) and calculated median values, respectively.

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4.5 DISCUSSION

4.5.1 Geochemical alteration

All data were calibrated for aragonite as almost all mineralogical analyses of Theba shells from different stratigraphic levels did not show any calcite. Although parts of one shell from sample E-8 and E-1 contained local traces of calcite, these may result from the incorporation of ground- derived calcite by the snail rather than mineral conversion. A mineral conversion into calcite would probably significantly influence the stable isotope results (see Lecuyer et al., 2020).

18 13 However, δ Oshell and δ Cshell signals do not correlate across the sequence and show no synchronous shifts. It would be conceivable, that different stable isotope ratios for palaeosurfaces compared to sandy layers may be due to different conditions for aragonite- calcite transformation processes in the respective environment. However, such effects would also have been revealed in the studies by Yanes et al. (2011). They analysed Theba shells in sand-palaeosurface sequences on the eastern Canary Islands regarding their microstructure (by x-ray diffraction (XRD) and raster electron micrographs) and stated, that aragonite-calcite transformation is negligible for the stable isotope analyses of terrestrial gastropod shells in these Quaternary deposits, independent from the lithofacies. This is also corroborated by the XRD and Raman analyses of this study, comparing modern Theba shells with Theba shells from the lowermost palaeosurface (sample E-8) as well as the lowermost sandy layer (sample E-1) and therefore seems to be applicable also for much older stratigraphic layers with ages over 300 ka. Accordingly, we suppose the prevalent fluctuations between palaeosurfaces compared to sandy layers in our sequence not to reflect diagenetic patterns, but to be dominated by other influences. Also, Xuefen et al. (2005) investigated the aragonite-calcite transformation of terrestrial gastropod shells in Chinese long-term loess records as well as in laboratory experiments and found, that temperature and pressure did apparently not influence the observed aragonite-calcite transformation in these terrestrial loess deposits. However, they found mineral conversion in the gastropod shells towards calcite in the lowermost strata of the deposits, indicating age-dependent calcite formation due to the metastable state of aragonite. They identified an age of 420 to 658 ka BP, from which the calcite transformation presumably takes place. Since we see a fluctuation between palaeosurfaces and sandy layers regardless of the age, and no differences between younger and older strata, there is no evidence for an age-related aragonite-calcite transformation in our sequence. Therefore, we propose, that calcite formation plays a negligible role in the analysed shell samples.

13 4.5.2 δ Cshell - C3 plants in palaeosurfaces and the role of edaphic humidity

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13 We presume the most positive δ Cshell signals at Encantado to be related to a higher consumption of C4 plants, while more negative values indicate a higher consumption of C3 plants (see chapter “Geographical setting and state of knowledge”). There is a general trend for samples that are related to palaeosurfaces such as samples E-10, E-12, E-19, E-20 and

13 E-26 to coincide with the most negative median values of δ Cshell, which, in turn, indicate moister conditions. Sample E-8 is an exception to this pattern, which may be due to an outlier

13 in the measured δ Cshell signals. The large standard deviation of 2.39‰ indicates that the median value for this sample may not be representative.

It may be conceivable that fluctuations in potentially ingested ground-derived carbonates

13 biased these δ Cshell values, as also carbonate contents at the Encantado site are continuously decreased within palaeosurfaces (see Roettig et al., 2019). Goodfriend & Hood (1983) assumed that up to 33% of land snail shell carbonate can be derived from the parent material. However, the carbonate content across the Encantado sequence is never less than 40% (Roettig et al., 2017) and the availability of lithogenic carbonate was therefore always saturated. This would suggest that the amount of incorporated ground derived carbonate in the snail shell should have been constant. However, Yanes et al. (2008) measured δ13C in carbonate rich sediments of Lanzarote and gained values between -1.4 and 1.6‰, which shows that the influence of calcium carbonate on gastropod shells would not only depend on the amount of ingested carbonate but also on its composition. In contrast to Goodfriend & Hood (1983), studies by Stott (2002) and Metref et al. (2003) showed that δ13C signals from snail shells are directly related to the δ13C signals of their soft tissues, but that both were not influenced by the consumption of carbonate or atmospheric CO2. To test this, we apply the flux

13 balance model from Balakrishnan and Yapp (2004). For the δ C values of atmospheric CO2, we take an average of -6.7‰ for glacial phases (Leuenberger et al., 1992) and of -8.4‰ (Graven et al., 2017) for modern (interglacial) times (Keeling et al., 1989) in the equations. The

CO2 partial pressure at the last glacial maximum was about 190 ppm (Oeschger et al., 1984), about 280 ppm for preindustrial times (Neftel et al., 1985) and 360 ppm at present (Keeling &

Whorf, 2002). Accordingly, there was an increase of 170 ppm for the CO2 partial pressure of the atmosphere for interglacial compared to glacial times. Applying the flux balance model

13 mentioned above and keeping all other variables constant (e.g., T = 16°C, φ = 0, δ CIN = - 10‰), this increase of the δ13C signals of the atmosphere would have caused a decrease of 0.05‰ in the δ13C signals of the gastropod shells for interglacial compared to glacial times. Comparing this order of magnitude to the maximal variability of the measured δ13C values of the gastropod shells of 8.41‰ we reason, that the influence of atmospheric CO2 would play a minor role compared to the influence of the ingested diet. However, we assume that possibly significant differences apply for metabolisms and lime storage behaviour of different taxa. In

117 the study of Goodfriend and Hood (1983) cited above, they investigated several tropical Jamaican taxa e.g., of Eutrochatella and Pleurodonte, even belonging to different clades. With focussing on Helix aspersa, Stott (2002) and Metref et al. (2003) investigated the same species under laboratory conditions thus reducing the influencing factors. Based on the close relation

13 of Theba and Helix, both pertaining to the family of Helicidae, we for now assume the δ Cshell signal in Theba to be food dominated.

13 Accordingly, we consider more negative peaks in median δ Cshell values to be mainly caused

13 by an increase in C3 plants. In support of this, the δ Cshell signals are negatively correlated to the Shannon biodiversity index (see Chapter “Results”). The gastropod biodiversity (Shannon

13 index and species richness, respectively) is highest for minima in δ Cshell median values,

13 equally indicating moister conditions. The most negative signals of δ Cshell median values (which imply moister conditions) can be allocated to palaeosurfaces. Additionally, we find an increase in C3 plants in samples from tephric layers (samples E-3, E-5, E-14, E-15 and E-17).

13 The more negative δ Cshell signals of the tephric layers compared to the subjacent and superjacent substrate (see Chapter “Results”) indicates that also tephric input is related to a significant moisture increase relative to the basic substrate of the lithological units. As volcanism usually occurs independent from climatic cycles, we suppose, that the volcanic ash had a significant effect on the distribution of C3 vs. C4 plants. The volcanic ash probably led to a refinement of the sediment, increasing its water retention capacity. Under the very arid climate conditions at the Eastern Canary Islands, dew plays a major role for the availability of water. In this context, a higher water storage capacity in finer substrates may have caused a higher edaphic humidity significantly affecting biota. Hence, there is evidence of a substrate- induced increased edaphic humidity independent of changes in local climatic conditions. This fact also suggests that the higher humidity that relates to the silty palaeosurfaces, may equally have been caused by edaphic humidity in a finer substrate, instead of a significantly wetter climate. This study shows the importance of differentiating between climatic and edaphic humidity in order to disentangle large-scale climate shifts from small-scale sedimentary effects.

4.5.3 Validation of the results with modern shell δ13C signals

13 Modern δ Cshell signals of this study vary between -6.68 and -8.39‰. Yanes et al. (2008) investigated carbon isotope ratios of four modern shells of Theba geminata from Montaña

13 Costilla close to the study area and gained results from -6.0 to -9.4‰. All these modern δ Cshell values are more negative than the fossil values of the Encantado profile and indicate a high proportion of C3 plants in the current environment.

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However, as modern gastropod shells were missing at the upper terrace of the study site, we took the modern gastropod shells from a microhabitat in the valley floor close by.

13 Consequently, the measured modern δ Cshell signals have to be treated with care and are possibly influenced by the different relief and soil water regime. We expect, that the occurrence of C3 plants in many places on the eastern Canary Islands (see Yanes et al., 2013) is equally biased by the relief and the degree of anthropogenic impact, as related substrate differences (e.g., erosion or the deposition of former silty surface sediments in depth lines) strongly influence the distinction of the plant cover (Rodríguez et al., 2005; Mora et al., 2012). Yanes

13 et al. (2008) measured δ Cshell signals of Theba geminata from two different localities at La Graciosa (north of Lanzarote). Values varied between -4.6 and 1.7‰. This scatter of values is comparatively high and with 6.3‰ almost as wide as the variation between all fossil samples of Encantado, which show a scatter of 8.41‰. This shows a strong difference between microhabitats under similar climatic conditions either due to different substrates (disclosed surface layer) or relief (see also Magaritz & Heller, 1983). Accordingly, we recommend comparing only shells of the same profile location to make environmental reconstructions across time.

The absence of gastropods at the upper terrace of our study site indicates a stressed ecosystem and unfavourable conditions, which is additionally supported by the sparse vegetation. However, the recent surface is not comparable to that of prehistoric times. Anthropogenic influence caused an enrichment of certain nutrients and severe erosion, that lead to degradation of the surface and a significantly lower water retention capacity (see Rodríguez et al., 2005; Mora et al., 2012). As the surface of our recent stability phase in less disturbed relief positions equals that of the fossil palaeosurfaces (also see Rodríguez et al., 2005), equally containing a high amount of dust, we propose that the higher biodiversity for palaeosurfaces recorded in our sediment sequence also applied to modern times before anthropogenic influence (also see Rodríguez et al., 2005; Mora et al., 2012).

4.5.4 Influences on δ18O in shells of the genus Theba – a special model for the oceanic setting of Fuerteventura

Based on the high oceanity of our study site and the specific behaviour of Theba, we propose

18 to simplify particular influences on the δ Oshell signals based on the following assumptions. (i) We neglect the influence of evaporation. Goodfriend et al. (1989) showed that the δ18O signal in Theba body fluids is strongly related to that of the shell carbonate, while shell growth mainly takes place during the active phases of snails (Goodfriend et al, 1989). It is furthermore known, that snails are usually active under relative humidity conditions above 85% (i.a. Balakrishnan and Yapp, 2004). Theba is active primarily at night (Yanes et al., 2008), absorbing mainly dew

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(Goodfriend et al., 1989). For the coastal areas of Fuerteventura, at night, the land-sea wind system flattens and moisture from the ocean reaches the island by the (trade) winds. Due to the nocturnal cooling, dew condensates under water-saturated conditions (dew point = 100% relative humidity). For these conditions, we suggest to neglect evaporation for the dew as well as transpiration by the snail (comp. Yanes et al., 2011). We neglect the influence of daytime activity phases due to rain events and associated effects of increased evaporation processes

18 on the δ Oshell signals due to the low annual rainfall amounts on Fuerteventura (127mm for Lajares) and the relatively low amount of rainwater intake compared to dew (Goodfriend et al., 1989). (ii) We propose that δ18O of environmental waters ingested by Theba in our setting correlate with δ18O of the marine surface seawater in the proximity to the island. The study site is located at a distance of 4 km from the sea. Measurements on environmental waters on the Eastern Canary Islands have been carried out by Yanes et al. (2008), who measured meteoric water samples. According to these studies, the location Tao on Lanzarote with a comparable distance to the ocean showed values of -2.0 to -2.6‰. Modelled mean annual δ18O values of the precipitation for Fuerteventura by Terzer et al. (2013) amount to -2 to -4‰. However, the mean annual δ18O signals of the precipitation have not been measured for the study site yet, nor have the (mean annual) δ18O signals of dew in this oceanic setting. Measurements by Ostlund et al. (1987) from west of the Canary Islands show mean ocean surface δ18O signals of 1.08‰. We expect the shift between δ18O in precipitation and δ18O of sea surface water and their bias by rainout effect, altitude effect, etc. to be smaller than in settings that are further inland or hillier. As δ18O rain is also influenced e.g., by sub-cloud evaporation, there furthermore is a difference between δ18O rain signals and δ18O signals of non-rainfall environmental waters. Kaseke et al. (2017) found dew to be more enriched in 18O compared to rainwater. Accordingly, we make the assumption that mean annual δ18O signals of the surface seawater and mean annual δ18O signals of the environmental waters (consumed by Theba) at our study site are correlated. Applying the flux balance model by Balakrishnan & Yapp (2004), and setting the humidity in this equation to 1.0 (100%), the temperature to the average annual minimum temperature (16 °C) and theta to 0 (which applies for the steady state between the hemolymph and the imbibed environmental waters/dew) and taking the average δ18O signals of the modern gastropod shells of this study (-0.67‰) as basis, we would

18 get mean δ OIN signals of the imbibed water of -1.52‰. Thus, we propose for our highly

18 18 oceanic insular environment that the δ Oprecipitation signal and accordingly δ Oshell might be correlated with marine isotope signals. These, in turn, considered for the same location across time may have the potential to reflect the global ice coverage indicating glacial-interglacial cycles.

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18 4.5.5 δ Oshell and sedimentation patterns – the shift between sea level fluctuations and palaeosurfaces

Based on the previous subchapter, we attempt a first approach in Fig. 8 to correlate δ18O signals of our terrestrial gastropods with marine isotopic signals in foraminifers of the photic zone. However, it should be kept in mind that a correlation into detail of δ18O curves from terrestrial gastropod shells and marine foraminifers is hardly possible and seems not appropriate, as beside the above-mentioned overlap of factors affecting δ18O in gastropod shells, likewise the type of sediment archive (aeolianite sequence) is not entirely suitable for producing continuous proxy curves. As a result of complex geomorphological processes, aeolianite sequences reveal sedimentation phases with varying sedimentation rates and interruptions of sedimentation by means of surface stability. Moreover, sedimentation gaps may result from the post-sedimentary erosion of sediment layers. And finally, the temporal resolution is rather an approximation considering the standard deviation of luminescence ages.

If, referring to Roettig et al. (2019), we assume that the succession of sandy layers and palaeosurfaces is related to marine sea level fluctuations, δ18O signals in our gastropod shells should similarly reflect these glacial-interglacial cycles. However, the signals of stable oxygen isotopes in the gastropod shells do not correlate continuously with the succession of palaeosurfaces and sandy layers, respectively. Possible explanations for these deviations may be: 1) despite the composition of the source signals of environmental waters ingested by the gastropods, other factors were (temporarily) more dominant; (2) the signals reflect marine isotope signals and thus glacial-interglacial cycles, but the succession of sand sheets and palaeosurfaces does not. Sedimentation patterns therefore may be influenced by multiple factors. For example, sand accumulation is highly dependent on the availability of sand, which, in turn, is controlled by sea level fluctuations (as regressions cause the exposure of shelf areas), but also the distance between the deposition sites and the sand source (as during glacial times the sea level has dropped markedly (e.g., Denton et al., 2010); the beach could have been too far away, to serve as a sand source). On the other hand, we assumed a more humid climate during colder phases, so that the shelf area was possibly covered with vegetation that hindered sand transport and possibly also led to a dust-dominated layer on our site. Furthermore, prevailing wind directions and wind strength or the coverage of potential sand sources by volcanic deposits (see Roettig et al., 2019) heavily influence the deposition of dune sands. For example, the palaeosurface related to sample E-10 is not accompanied by

18 a decrease of δ Oshell. Consequently, it could be assumed that the deposits of interglacial times have not been preserved or that the respective deposits were not formed at the same time as a transgression took place.

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As already mentioned, the temporal resolution of glacial and interglacial periods of the aeolianite sequences is fraught with many uncertainties. But even if we have to evaluate the results with caution, there is a trend for palaeosurfaces to directly relate to rapid decreases in

18 the δ Oshell signals of more than 1‰ between two consecutive samples that, in turn, are assumed to be related to marine transgressions. If we apply the flux balance model by Balakrishnan and Yapp (2004) defining that the relative humidity (e.g., 100%) and

18 18 temperatures stay constant, we have a shift of 1‰ in δ Oshell, for every shift of 1‰ δ O of the imbibed liquid/dew. Empirical studies by Lecolle (1985), Prendergast et al. (2015), Zanchetta et al. (2005) and Yanes et al. (2017) similarly indicate that an average increase of 0.5 to 1‰ (PDB) in snail shell δ18O signals relate to an increase of 1‰ (SMOW) in rain δ18O signals (Yanes et al., 2017, 2018). Rohling (2013) suggests an overall increase of 0.012 ± 0.001‰ in

18 18 δ Oseawater per 1m of sea level fall (1.8‰ in δ Oseawater for a sea level fall of 150 m). Hodell et al. (2013) measured foraminifera of the photic zone encountering a shift of 2.9‰ between

18 glacial-interglacial phases. Median values of δ Oshell signals of our terrestrial gastropods show a range of 2.66‰ and are relatively close to the aforementioned spectra. The results may be biased by the continentality effect caused by sea level low- compared to sea level high stands. However, according to Rozanski et al. (1993), the continentality effect causes a depletion of 2‰ in δ18O /1000 km. Glacial-Interglacial sea level fluctuations yielded a maximal shift of 150 m a.s.l. (Denton et al., 2010) which would cause a maximal coastline shift of about 10 km distance for Fuerteventura (see Roettig et al., 2019). Accordingly, this effect would be negligible. However, the correlation between sea level rises being related to a depletion in 18O of the gastropod shells would be in line with the hypothesis that palaeosurfaces and their preservation relate to phases of surface stability.

18 18 Modern δ Oshell signals with a median of -0.65‰ are more depleted on O than those of the upper section of the Encantado profile with a mean of 1.23‰ and were dated to around 16 ka (Roettig et al., 2017). Due to the azonal sampling of the modern shells, different

18 environmental conditions may have affected the δ Oshell signals, e.g., an influence by different hydrology at the lower position. However, our results are close to the results of Yanes et al. (2011) who measured signals of 0.1 to 0.3‰ for modern shells and 1.6 to 1.8‰ for the last glacial maximum, respectively. The deviations may reflect local differences. Assuming that

18 these signals are dominated by the marine isotope composition, lower modern δ Oshell values indicate a lower global ice volume compared to the underlying presumed glacial age deposits, which is consistent with the level of knowledge on the Holocene situation.

4.5.6 Marine transgressions: Hot winds bring extinction - and subsequent stability induces new communities?

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As mentioned above, we relate rapid decreases in δ18O of gastropod shells on Fuerteventura to marine transgressions that in most cases were followed by the formation of palaeosurfaces. As a trend, these rapid decreases in the heavy 18O isotope are linked to significant changes in the malacofauna and the formation of new malacozones (MZ). These changes become obvious e.g., between the stratigraphic positions of samples E-7 (MZ B) and E-8 (MZ C) marked by the disappearance of Obelus pumilio that prefers mild conditions and does not tolerate too hot summers (see Richter et al., 2019). The subsequent biocoenosis had been established in the following palaeosurface with Canariella plutonia, Ferussacia fritschi, Hemicycla flavistoma, Hemicycla sarcostoma etc. Another shift applies between samples E- 10 (MZ C) and 11 (MZ D) with the eradication of the majority of species like Cochlicella n. sp., Cryptella auriculata and Hemicycla paeteliana. As soon as a finer substrate is preserved, which has a higher water retention capacity (sample E-12), a new gastropod community establishes with Pomatias sp. lanzarotensis and re-establishment of Cryptella auriculata. There are further

18 rapid decreases in δ Oshell with a change of the malacozone between samples E-16 (MZ F) and E-17 (MZ D) and E-18 (MZ D) and E-19 (MZ E(b)). Sample E-19 again coincides with the dusty facies of a palaeosurface and leads to re-establishment of a new gastropod community (Upper Pomatias fauna). There is lithofacial evidence for the previous samples E-16 to E-18 that they were additionally disturbed by erosion caused by event-like surface runoff and strong volcanic influence as indicated by thin sections, which show an increased proportion of volcanic glasses (see Roettig et al., 2019). This geomorphological instability might have led to the erosion of a potential palaeosurface and also may explain the low gastropod biodiversity related to samples E-16 to E-18. The faunal change between samples E-23 (MZ E(b)) and E- 24 (MZ H) is not related to significant changes in δ18O signals or the formation of a palaeosurface, respectively. Here, the faunal change could either have been caused by too intense volcanic activity, or the related strata may have been eroded. The stratigraphic resolution of this upper section is not high enough to provide a solid interpretation.

However, we assume that the overall displacement of species was related to climatic and/or environmental changes in the study area, that are also reflected in the rapid decreases

18 in δ Oshell presumably linked to significant transgressions that introduced interglacial and interstadial periods, respectively. We propose, that the most important climatic/environmental features causing abrupt faunal changes may have been linked to strong winds during these transitional phases as found by Moreno et al. (2001) in marine cores of the Northern Canary Basin. They revealed that wind strength maxima and vast dust input occurred during precessional minima associated with higher seasonality and related to glacial-interglacial transitions. These would have caused hotter summers with hot and dry winds, which, in turn, may have led to the disappearance of more sensitive gastropod species. These hot and dry

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winds additionally brought vast amounts of dust. However, the accumulation of dust caused a considerable refinement of the substrate that finally resulted in a kind of opposite effect on hydrological conditions. As seen by tephric layers (samples E-2, E-5, E-15 and E-23) such substrate refinement had a positive effect on the local flora independent of direct climatic changes. A dominance of C3 plants in finer tephric layers indicates wetter conditions. Therefore, we assume that geomorphic stability during marine transgressions and an enhanced water storage capacity of the silty palaeosurface favoured the establishment of new gastropod communities independent from changes in local climatic conditions. This is in line with the results of Richter et al. (2019), who found that paleosurfaces are related to higher gastropod abundances and increased availability of resources such as food, but are not necessarily linked to a change in the biozone. To substantiate this, more investigations on the influence of certain environmental factors are necessary. Moreover, a higher number of shell measurements on gastropod material would help to improve the representativeness, while further luminescence dating could help to obtain a more complete picture of this complex system in high resolution.

Fig. 4.8 The section Encantado plotted with malacozonation and derived environmental conditions according to Richter et al., 2019 (left), biodiversity, and distribution of Hemicycla spp. indicating a distinct plant cover (modified from Richter et al., 2019), δ13C signals of the gastropod shells that indicate the drought stress level of consumed plants (green to orange scale) as well as δ18O signals of the gastropod shells which reflect the precipitation/dew signal that in our special study location is assumed to be related to the marine signal (blue to red scale). Purple arrows on the left side mark changes of the biozones 18 while orange arrows indicate marine transgressions as derived from δ Oshell signals, both are assumed to correspond to glacial terminations (e.g., T I to T III described by Moreno et al., 2001). For comparison, red and blue curves show δ18O signals of planktonic foraminifera (red) generated by Hodell et al. (2013) and of a synthetic Greenland temperature curve (GLT_syn) from Barker et al. (2011) (blue) calculated from the deuterium record of the Antarctic EDC ice core for the last 400 ka. The black curves on the right show wind strength (Si/Al) and dust deposition (Fe/Al) proxies from Moreno et al. (2001). For coloured figures we refer to the web version of the article.

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4.6 CONCLUSIONS

Multiple factors influence δ18O signals in terrestrial gastropod shells. These factors are assumed to vary in their character and dominance across time. However, we assume that δ18O signals in Theba shells of the investigated highly oceanic island Fuerteventura predominantly reflect shifts in marine sea surface δ18O signals. Thus, they allow a chronological allocation of our deposits with respect to sea level fluctuations caused by glacial-interglacial cycles. We assume that rapid decreases in δ18O signals of the shells indicate significant transgressions related to increasing global temperatures that follow glacial maxima. These decreases in δ18O in the shells simultaneously relate to malacozone boarders with changing gastropod associations (Richter et al, 2019) that indicate stronger environmental changes. We assume that these faunal transitions were possibly caused by strong hot winds together with higher seasonality that were described by Moreno et al. (2001) for terminations of glacial phases. These atmospheric patterns were primarily forced by precession minima as shown e.g., by

18 Moreno et al. (2001). Rapid decreases in δ Oshell were followed by geomorphologically stable phases that related to dust accumulation and preservation dominating the palaeosurface formation. Palaeosurfaces in our deposits were coupled with an increased gastropod biodiversity and soil moisture, indicated by a higher proportion of C3 plants derived from more

13 negative δ Cshell signals. We propose that the formation of palaeosurfaces was not primarily an effect of changing local climatic conditions. Rather, the ecosystems on Fuerteventura seem to respond to changes in the substrate caused either by input of dust or tephric material. Our study demonstrates the importance of distinguishing between climatic and edaphic humidity in order to separate large-scale climate shifts from small-scale sedimentary effects. We therefore propose that stable isotope signals can be a valuable proxy for palaeoclimatic and palaeoecological reconstructions, especially at oceanic islands and allow to link them with glacial-interglacial and accordingly to stadial-interstadial shifts. Nevertheless, we recommend using stable isotope signals in gastropod shells in combination with analyses of the gastropod assemblages and a solid stratigraphic background.

4.7 ACKNOWLEDGEMENT

This work was funded by the German Research Foundation (DFG, FA 239/18-1). Furthermore, the work of the first author was financed through a Graduate research fellowship of the TU Dresden. We would like to thank Prof. Dr. Yurena Yanes and Dr. Klaus Groh for their help in the identification of Canary gastropod species as well as Prof. Dr. Joachimski for the stable isotope measurements. We would also like to thank Philipp Baumgart and Florian Schneider for their support in the field work.

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4.8 REFERENCES

Balakrishnan M, Yapp CJ (2004): Flux balance models for the oxygen and carbon isotope compositions of land snail shells. Geochimica et Cosmochimica Acta, 68(9), 2007-2024.

Balakrishnan M, Yapp CJ, Theler et al. (2005): Environmental significance of 13C/12C and 18O/16O ratios of modern land-snail shells from the southern great plains of North America. Quaternary Research, 63(1), 15-30.

Barker S, Knorr G, Edwards RL et al. (2011): 800,000 years of abrupt climate variability. Science, 334, 347-351.

Bouab N, Lamothe M (1997): Geochronological framework for the Quaternary paleoclimatic record of the Rosa Negra Section (Fuerteventura, Canary Islands). In: Meco J, Petit-Maire N (Eds.): Climates of the Past. Fuerteventura and Lanzarote. UNESCO International Union of Geological Sciences, 37-42.

Coello JJ, Castillo C, González EM (1999): Stratigraphy, chronology, and palaeoenvironmental reconstruction of the quaternary sedimentary infilling of a volcanic tube in Fuerteventura, Canary Islands. Quaternary Research, 52, 360–368.

Colonese AC, Zanchetta G, Fallick AE et al. (2014): Oxygen and carbon isotopic composition of modern terrestrial gastropod shells from Lipari Island, Aeolian Archipelago (Sicily). Palaeogeography, Palaeoclimatology, Palaeoecology, 394, 119-127.

Criado C, Dorta P (2003): An unusual ‘blood rain’ over the Canary Islands (Spain). The storm of January 1999. Journal of Arid Environments, 55, 765-783.

Criado C, Torres JM, Hansen A et al. (2011): Intercalaciones de polvo sahariano en paleodunas bioclásticas de Fuerteventura (Islas Canarias). Cuaternario y Geomorfología, 26(1–2), 73-88.

Damnati B, Petit-Maire N, Fontugne M et al. (1996): Quaternary palaeoclimates in the eastern Canary Islands. Quaternary International, 31, 37–46.

Denton GH, Anderson RF, Toggweiler JR, Edwards RL, Schaefer JM, Putnam AE (2010): The last glacial termination. Science, 328(5986), 1652-1656.

Ehleringer JR (1989): Carbon isotope ratios and physiological processes in arid land plants. In: Rundel PW, Ehleringer JR, Nagy KA (Eds.): Stable isotopes in ecological research. Ecological Studies, 68, 41-54.

Faust D, Yanes Y, Willkommen T et al. (2015): A contribution to the understanding of late Pleistocene dune sand-paleosol-sequences in Fuerteventura (Canary Islands). Geomorphology, 246, 290-304.

Goodfriend GA, Hood DG (1983): Carbon isotope analysis of land snail shells: implications for carbon sources and radiocarbon dating. Radiocarbon, 25(3), 810–830.

127

Goodfriend GA, Magaritz M (1987): Carbon and oxygen isotope composition of shell carbonate of desert land snails. Earth and Planetary Science Letters, 86(2), 377-388.

Goodfriend GA, Magaritz M, Gat JR (1989): Stable isotope composition of land snail body water and its relation to environmental waters and shell carbonate. Geochimica et Cosmochimica Acta, 53(12), 3215-3221.

Goodfriend GA (1990): Rainfall in the Negev Desert during the middle Holocene, based on 13C of organic matter in land snail shells. Quaternary Research, 34(2), 186-197.

Goodfriend GA (1992): The use of land snail shells in paleoenvironmental reconstruction. Quaternary Science Reviews, 11(6), 665-685.

Graven H, Allison CE, Etheridge DM et al. (2017): Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP6. Geoscientific Model Development, 10(12).

Hodell DA, Crowhurst S, Skinner L et al. (2013): Response of Iberian Margin sediments to orbital and suborbital forcing over the past 420 ka. Paleoceanography, 28, 1–15.

Jahn R (2010): Impact of aeolian sediments on pedogenesis – examples from the fringe area of the Saharan desert. 19th World Congress of Soil Science. In: Proceedings of the International Union of Soil Science, Wageningen. Brisbane, Australia.

Juan C, Emerson BC, Oromi P et al. (2000): Colonization and diversification: towards a phylogeographic synthesis for the Canary Islands. Trends in Ecology and Evolution, 15, 104– 109.

Kaseke KF, Wang L, Seely MK (2017): Nonrainfall water origins and formation mechanisms. Science Advances, 3(3), e1603131.

Keeling CD, Bacastow RB, Carter AF et al. (1989): A three-dimensional model of atmospheric

CO2 transport based on observed winds: 1. Analysis of observational data. In Aspects of Climate Variability in the Pacific and Western Americas (ed. DH Peterson), pp. 165–235. Geophysical Monograph 55. American Geophysical Union.

Keeling CD, Whorf TP (2002): Atmospheric CO2 records from sites in the SIO air sampling network. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy.

Kehrwald NM, McCoy WD, Thibeault J et al. (2010): Paleoclimatic implications of the spatial patterns of modern and LGM European land-snail shell δ18O. Quaternary Research, 74(1), 166-176.

Kim ST, Mucci A, Taylor BE (2007): Phosphoric acid fractionation factors for calcite and aragonite between 25 and 75 °C: Revisited. Chemical Geology, 246, 135-146.

128

Lafuente B, Downs RT, Yang H et al. (2015): The power of databases: the RRUFF project. In: Armbruster T, Danisi RM (Eds.): Highlights in Mineralogical Crystallography. Berlin, Germany, W. De Gruyter, 1-30.

Lécolle P (1985): The oxygen isotope composition of landsnail shells as a climatic indicator: applications to hydrogeology and paleoclimatology. Chemical Geology: Isotope Geoscience section, 58(1), 157-181.

Lécuyer C, Marco AS, Lomoschitz A, Betancort JF, Fourel F, Amiot R, Clauzel T, Flandrois JP, Meco J (2020): δ18O and δ13C of diagenetic land snail shells from the Pliocene (Zanclean) of Lanzarote, Canary Archipelago: Do they still record some climatic parameters?. Journal of African Earth Sciences, 162, 103702.

Leuenberger M, Siegenthaler U, Langway C (1992): Carbon isotope composition of atmospheric CO2 during the last ice age from an Antarctic ice core. Nature, 57(6378), 488-490. Liu Z, Gu Z, Wu N et al. (2007): Diet control on carbon isotopic composition of land snail shell carbonate. Chinese Science Bulletin, 52(3), 388-394.

Magaritz M, Heller J (1983): Annual cycle of 18O/16O and 13C/12C isotope ratios in landsnail shells. Chemical Geology, 41, 243-255.

Magurran, AE (1988): Ecological Diversity and its Measurement. Princeton University Press, Princeton, pp. 7-45.

Marshall JD, Brooks JR, Lajtha K (2007): Sources of variation in the stable isotopic composition of plants. In: Lajtha K, Michener RH (1994): Stable isotopes in ecology and environmental science. Blackwell Scientific Publications, 22-60.

McConnaughey TA, Gillikin DP (2008): Carbon isotopes in mollusk shell carbonates. Geo- Marine Letters, 28(5-6), 287-299.

McQuad CD, Branch GM, Frost PGH (1979): Aestivation behaviour and thermal relations of the pulmonate Theba pisana in a semi-arid environment. Journal of Thermal Biology, 4(1), 47- 55.

Meco J, Pomel R (1985): Les formations marines et continentales intervolcaniques des Iles Canaries orientales (Grande Canarie, Fuerteventura et Lanzarote): Stratigraphie et signification paléoclimatique. Estudios geológicos, 41, 223–227.

Metref S, Rousseau DD, Bentaleb I et al. (2003): Study of the diet effect on δ13C of shell carbonate of the land snail Helix aspersa in experimental conditions. Earth and Planetary Science Letters, 211(3), 381-393.

Mora JL, Armas-Herrera CM, Guerra JA et al. (2012): Factors affecting vegetation and soil recovery in the Mediterranean woodland of the Canary Islands (Spain). Journal of arid environments, 87, 58-66.

129

Moreno A, Targarona J, Henderiks J et al. (2001). Orbital forcing of dust supply to the North Canary Basin over the last 250 kyr. Quaternary Science Reviews, 20(12), 1327-1339.

Moreno A, Sancho C, Bartolomé M et al. (2014): Climate controls on rainfall isotopes and their effects on cave drip water and speleothem growth: the case of Molinos cave (Teruel, NE Spain). Climate dynamics, 43(1-2), 221-241.

Muhs DR (2013): The geologic records of dust in the Quaternary. Aeolian Research, 9, 3–48.

Neftel A, Moor E, Oeschger H et al. (1985): Evidence from polar ice cores for the increase in atmospheric CO2 in the past two centuries. Nature, 315(6014), 45-47.

Oeschger H, Beer J, Siegenthaler U et al. (1984): Late glacial climate history from ice cores. Climate processes and climate sensitivity, 29, 299-306.

Ortiz JE, Torres T, Yanes Y et al. (2006): Climatic cycles inferred from the aminostratigraphy and aminochronology of Quaternary dunes and palaeosols from the eastern islands of the Canary Archipelago. Journal of Quaternary Science, 21, 287–306.

Ostlund, HG, Craig H, Broecker WS et al. (1987): GEOSECS Atlantic. Pacific, and Indian Ocean Expeditions, 7, 80.

Peel MC, Finlayson BL, Mcmahon TA (2007): Updated world map of the Köppen-Geiger climate classification. Hydrology and Earth System Sciences, 11, 1633-1644, https://doi.org/10.5194/hess-11-1633-2007.

Prendergast AL, Stevens RE, Barker G et al. (2015): Oxygen isotope signatures from land snail (Helix melanostoma) shells and body fluid: Proxies for reconstructing Mediterranean and North African rainfall. Chemical Geology, 409, 87-98.

Prendergast AL, Stevens RE, Hill EA et al. (2017). Carbon isotope signatures from land snail shells: Implications for palaeovegetation reconstruction in the eastern Mediterranean. Quaternary International, 432, 48-57.

Richter C, Roettig CB,Wolf D et al. (2019): Changes in Pleistocene gastropod faunas on Fuerteventura (Canary Islands) and implications on shifting palaeoenvironmental conditions. Quaternary Science Reviews, 209, 63-81.

Roettig CB, Kolb T, Wolf D et al. (2017): Complexity of Quaternary aeolian dynamics (Canary Islands). Palaeogeography. Palaeoclimatology. Palaeoecology, 472, 146-162.

Roettig CB, Varga G, Sauer D et al. (2019): Characteristics, nature and formation of palaeosurfaces within dunes on Fuerteventura. Quaternary Research, 91(1), 4-23.

Roettig CB, Kolb T, Zöller L et al. (2020): A detailed chrono-stratigraphical record of canarian dune archives-Interplay of sand supply and volcanism. Journal of Arid Environments, 183, 104240.

130

Rodríguez AR, Mora JL, Arbelo C et al. (2005): Plant succession and soil degradation in desertified areas (Fuerteventura, Canary Islands, Spain). Catena, 59 (2), 117-131.

Rognon P, Coudé-Gaussen G, Le Coustumer MN et al. (1989): Lemassif dunaire de Jandía (Fuerteventura, Canaries): Évolution des paléoenvironnements de 20.000 BP à l'actuel. Quaternaire, 26(1), 31-37.

Rosenbaum J, Sheppard SM (1986): An isotopic study of siderites, dolomites and ankerites at high temperatures. Geochimica et Cosmochimica Acta, 50, 1147-1150.

Rozanski K, Araguás-Araguás L, Gonfiantini R (1993): Isotopic patterns in modern global precipitation. Geophysical Monograph, 78, 1-36.

Schneider F, Roettig CB, Wolf D et al. (2020): Rock magnetics of carbonate systems- investigating palaeodune archives on Fuerteventura (Canary Islands). Journal of Quaternary Science, 35(4), 594-606.

Shannon, CE (1948): A mathematical theory of communication. Bell System Technical Journal, 27, 379-423.

Siegenthaler U (1979): Stable Hydrogen and Oxygen Isotopes in the Water Cycle. In: Jäger E, Hunziker JC (eds): Lectures in Isotope Geology. Springer, Berlin, Heidelberg.

Stott, LD (2002): The influence of diet on the δ13C of shell carbon in the pulmonate snail Helix aspersa. Earth and Planetary Science Letters, 195(3-4), 249-259.

Suchodoletz HV, Kühn P, Hambach U et al. (2009): Loess-like and palaeosol sediments from Lanzarote (Canary Islands/Spain) - indicators of palaeoenvironmental change during the Late Quaternary. Palaeogeography Palaeoclimatology Palaeoecology, 278, 71–87.

Terzer S, Wassenaar LI, Araguás-Araguás LJ et al. (2013): Global isoscapes for d18O and d2H in precipitation: improved prediction using regionalized climatic regression models. Hydrology and Earth System Sciences Discussions 10(6), 7351-7393.

Xuefen S, Jun C, Yuanfeng C et al. (2005): Aragonite-calcite transformation in fossil snail shells of loess sequences in Loess Plateau, Central China. Chinese Science Bulletin, 50(9), 891.

Yanes Y, Delgado A, Castillo C et al. (2008): Stable isotope (δ18O, δ13C, and δD) signatures of recent terrestrial communities from a low-latitude, oceanic setting: endemic land snails, plants, rain, and carbonate sediments from the eastern Canary Islands. Chemical Geology, 249(3), 377-392.

Yanes Y, Yapp CJ, Ibáñez M et al. (2011): Pleistocene-Holocene environmental change in the Canary Archipelago as inferred from the stable isotope composition of land snail shells. Quaternary Research, 75(3), 658-669.

131

Yanes Y, Asta MP, Ibáñez M et al. (2013). Paleoenvironmental implications of carbon stable isotope composition of land snail tissues. Quaternary research, 80(3), 596-605.

Yanes Y, Al-Qattan NM, Rech JA et al. (2018): Overview of the oxygen isotope systematics of land snails from North America. Quaternary Research, 91(1), 329-344.

Yapp CJ (1979): Oxygen and carbon isotope measurements of land snail shell carbonate. Geochimica et Cosmochimica Acta, 43(4), 629-635.

Zanchetta G, Leone G, Fallick AE et al. (2005): Oxygen isotope composition of living land snail shells: Data from Italy. Palaeogeography, Palaeoclimatology, Palaeoecology, 223(1), 20-33.

Zhang N, Yamada K, Yoshida N (2018): Food water contribution to the oxygen isotope composition of land snail body water and its environmental implication. Geochemistry, Geophysics, Geosystems, 19(6), 1800-1808.

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4.9 SUPPLEMENTARY MATERIAL

Tab. 4.2: δ13C signals with mean values and related standard deviation for Encantado (E-1 to E- 27) and modern snail shells (modern) collected at a comparatively moist valley floor close by.

δ13C in ‰ (V- PDB) Sample shell1 Std.dev. shell2 Std.dev. shell3 Std.dev. shell4 Std.dev. Mean Std.dev. Median ID E-1 -3,29 ± 0,03 -2,90 ± 0,06 -5,45 ± 0,02 -4,69 ± 0,05 -4,08 ± 1,03 -4,0 E-2 -5,47 ± 0,04 -5,84 ± 0,02 -4,87 ± 0,05 -2,19 ± 0,07 -4,59 ± 1,43 -5,2 E-3 1,46 ± 0,08 -5,39 ± 0,06 -5,85 ± 0,06 -6,72 ± 0,05 -4,12 ± 3,26 -5,6 E-4 -1,69 ± 0,05 -3,68 ± 0,08 -4,92 ± 0,07 -5,16 ± 0,04 -3,87 ± 1,38 -4,3 E-5 -5,51 ± 0,04 -5,27 ± 0,08 -5,87 ± 0,01 -5,01 ± 0,03 -5,42 ± 0,32 -5,4 E-6 -4,19 ± 0,04 -2,89 ± 0,05 -5,69 ± 0,02 -6,23 ± 0,05 -4,75 ± 1,31 -4,9 E-7 -5,21 ± 0,08 -6,04 ± 0,05 -0,24 ± 0,07 -5,88 ± 0,06 -4,34 ± 2,39 -5,5 E-8 -4,57 ± 0,06 -5,74 ± 0,06 0,34 ± 0,05 -4,96 ± 0,06 -3,73 ± 2,39 -4,8 E-9 -3,74 ± 0,05 -5,32 ± 0,06 -4,60 ± 0,05 -3,28 ± 0,05 -4,23 ± 0,79 -4,2 E-10 -6,82 ± 0,02 -6,27 ± 0,02 -6,36 ± 0,02 -5,93 ± 0,01 -6,34 ± 0,32 -6,3 E-11 -2,74 ± 0,06 -3,66 ± 0,02 -5,31 ± 0,04 -5,22 ± 0,05 -4,23 ± 1,08 -4,4 E-12 -6,88 ± 0,06 -5,78 ± 0,08 -6,79 ± 0,07 -6,20 ± 0,05 -6,41 ± 0,45 -6,5 E-13 -5,70 ± 0,07 -4,51 ± 0,04 -5,24 ± 0,07 -4,61 ± 0,07 -5,02 ± 0,49 -4,9 E-14 -4,84 ± 0,04 -2,17 ± 0,01 -4,33 ± 0,05 -2,86 ± 0,06 -3,55 ± 1,08 -3,6 E-15 -4,72 ± 0,07 -4,91 ± 0,05 -4,63 ± 0,06 -5,49 ± 0,07 -4,94 ± 0,33 -4,8 E-16 -5,65 ± 0,04 -3,14 ± 0,02 -1,99 ± 0,03 -2,83 ± 0,05 -3,40 ± 1,36 -3,0 E-17 -4,23 ± 0,05 -4,89 ± 0,06 -4,74 ± 0,02 -0,81 ± 0,03 -3,67 ± 1,67 -4,5 E-18 -2,53 ± 0,07 -0,82 ± 0,04 -4,82 ± 0,03 -2,58 ± 0,05 -2,69 ± 1,42 -2,6 E-19 -2,13 ± 0,05 -6,68 ± 0,02 -3,98 ± 0,05 -4,01 ± 0,05 -4,20 ± 1,62 -4,0 E-20 -5,90 ± 0,05 -4,01 ± 0,05 -6,35 ± 0,06 -2,77 ± 0,06 -4,76 ± 1,44 -5,0 E-21 -5,25 ± 0,05 -3,47 ± 0,08 -3,27 ± 0,02 -1,20 ± 0,04 -3,30 ± 1,43 -3,4 E-23 -4,86 ± 0,04 -4,35 ± 0,02 -4,16 ± 0,03 -4,70 ± 0,05 -4,52 ± 0,28 -4,5 E-24 -5,77 ± 0,01 -5,24 ± 0,07 -4,33 ± 0,05 -5,27 ± 0,01 -5,15 ± 0,52 -5,3 E-25 -4,34 ± 0,07 -6,57 ± 0,06 -6,09 ± 0,07 -4,72 ± 0,03 -5,43 ± 0,92 -5,4 E-26 -5,91 ± 0,01 -3,73 ± 0,06 -6,95 ± 0,05 -6,84 ± 0,05 -5,86 ± 1,29 -6,4 E-27 -4,92 ± 0,06 0,62 ± 0,06 -4,41 ± 0,04 -4,17 ± 0,05 -3,22 ± 2,23 -4,3 modern -8,39 ± 0,05 -8,29 ± 0,03 -7,93 ± 0,05 -6,68 ± 0,06 -7,82 ± 0,68 -8,1

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Tab. 4.3: δ18O signals with mean values and related standard deviation and medians for Encantado (E-1 to E-27) and modern snail shells (modern) collected at a comparatively moist valley floor close by.

δ18O in ‰ (V-PDB) Sample ID shell1 shell2 shell3 shell4 calc Std.dev. arag calc Std.dev. arag calc Std.dev. arag calc Std.dev. arag Mean Std.dev. Median E-1 1,51 ± 0,01 1,13 1,55 ± 0,03 1,17 -0,94 ± 0,03 -1,32 0,87 ± 0,05 0,49 0,37 ± 1,01 0,81 E-2 0,92 ± 0,02 0,55 0,88 ± 0,01 0,50 -0,37 ± 0,03 -0,75 1,31 ± 0,04 0,93 0,31 ± 0,63 0,52 E-3 1,52 ± 0,06 1,14 -0,37 ± 0,04 -0,75 1,36 ± 0,03 0,98 0,08 ± 0,05 -0,30 0,27 ± 0,81 0,34 E-4 1,50 ± 0,04 1,13 2,10 ± 0,04 1,73 1,31 ± 0,04 0,93 1,28 ± 0,03 0,90 1,17 ± 0,33 1,03 E-5 0,98 ± 0,04 0,60 1,36 ± 0,05 0,98 1,49 ± 0,02 1,12 1,29 ± 0,04 0,92 0,90 ± 0,19 0,95 E-6 1,91 ± 0,02 1,53 1,39 ± 0,03 1,01 1,72 ± 0,02 1,34 1,48 ± 0,05 1,10 1,25 ± 0,20 1,22 E-7 2,09 ± 0,08 1,71 1,87 ± 0,04 1,49 2,47 ± 0,04 2,09 1,88 ± 0,03 1,51 1,70 ± 0,24 1,61 E-8 0,33 ± 0,04 -0,05 1,09 ± 0,02 0,71 0,37 ± 0,07 -0,01 0,30 ± 0,04 -0,07 0,14 ± 0,33 -0,03 E-9 1,61 ± 0,05 1,24 0,78 ± 0,03 0,40 -0,16 ± 0,05 -0,53 0,19 ± 0,02 -0,19 0,23 ± 0,67 0,10 E-10 1,86 ± 0,02 1,49 1,29 ± 0,02 0,91 1,49 ± 0,03 1,11 0,26 ± 0,01 -0,12 0,85 ± 0,60 1,01 E-11 1,39 ± 0,04 1,01 0,82 ± 0,01 0,44 -0,56 ± 0,04 -0,94 -0,52 ± 0,02 -0,90 -0,10 ± 0,85 -0,23 E-12 -0,56 ± 0,04 -0,94 0,82 ± 0,05 0,45 1,24 ± 0,04 0,87 0,16 ± 0,05 -0,22 0,04 ± 0,68 0,11 E-13 -0,12 ± 0,05 -0,50 0,43 ± 0,01 0,05 0,64 ± 0,03 0,26 0,55 ± 0,04 0,17 0,00 ± 0,30 0,11 E-14 0,18 ± 0,05 -0,19 0,79 ± 0,01 0,41 0,34 ± 0,05 -0,03 0,95 ± 0,03 0,58 0,19 ± 0,31 0,19 E-15 0,36 ± 0,05 -0,01 0,46 ± 0,05 0,08 0,41 ± 0,03 0,03 0,98 ± 0,06 0,60 0,18 ± 0,25 0,06 E-16 0,74 ± 0,02 0,37 0,81 ± 0,02 0,43 0,93 ± 0,03 0,55 1,36 ± 0,04 0,98 0,58 ± 0,24 0,49 E-17 -0,83 ± 0,03 -1,20 -0,58 ± 0,04 -0,96 -1,11 ± 0,02 -1,49 0,17 ± 0,03 -0,20 -0,96 ± 0,48 -1,08 E-18 1,23 ± 0,04 0,85 1,82 ± 0,04 1,44 0,50 ± 0,02 0,12 1,23 ± 0,04 0,85 0,82 ± 0,47 0,85 E-19 -0,26 ± 0,04 -0,64 -0,94 ± 0,03 -1,32 0,67 ± 0,04 0,29 1,44 ± 0,04 1,07 -0,15 ± 0,91 -0,17 E-20 1,92 ± 0,05 1,54 1,35 ± 0,04 0,97 -0,18 ± 0,05 -0,56 1,43 ± 0,07 1,05 0,75 ± 0,79 1,01 E-21 1,43 ± 0,03 1,05 1,97 ± 0,06 1,59 0,79 ± 0,01 0,41 0,84 ± 0,04 0,46 0,88 ± 0,48 0,76 E-23 1,98 ± 0,03 1,60 0,86 ± 0,01 0,49 0,67 ± 0,02 0,29 2,15 ± 0,05 1,77 1,04 ± 0,65 1,04 E-24 0,66 ± 0,03 0,28 1,26 ± 0,07 0,88 0,94 ± 0,03 0,56 1,16 ± 0,02 0,78 0,63 ± 0,23 0,67 E-25 1,49 ± 0,06 1,12 1,33 ± 0,04 0,96 1,74 ± 0,06 1,36 1,69 ± 0,02 1,31 1,19 ± 0,16 1,21 E-26 0,88 ± 0,01 0,50 2,64 ± 0,05 2,26 1,78 ± 0,03 1,41 0,94 ± 0,04 0,56 1,18 ± 0,72 0,98 E-27 1,75 ± 0,07 1,37 1,72 ± 0,03 1,34 1,31 ± 0,03 0,94 1,48 ± 0,04 1,11 1,19 ± 0,18 1,23 modern -0,40 ± 0,04 -0,45 -0,16 ± 0,05 -0,93 -0,07 ± 0,02 -0,77 -0,55 ± 0,03 -0,53 -0,67 ± 0,19 -0,65 calc.. calcite arag.. aragonite (callibrated according to the methods chapter)

134

Fig. 4.9: a) Raman spectra of alpine calcite, as well as calcite and aragonite specimens from the RRUFF database, b) Raman spectra of the two modern Theba shells, c) Raman spectra of the four Theba shells of sample E3-8, d) Raman spectra of the four Theba shells of sample E3-1, e) XRD spectra of one shell from sample E3-8 and one shell from sample E3-1 plotted against reference spectrum of aragonite PDF 75-2230.

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5 MALACOLOGICAL INVESTIGATIONS AT SOUTH CAUCASIAN SEDIMENT ARCHIVES – STABLE ISOTOPE INTERPRETATION IN A CONTINENTAL SETTING

Chapter 5 is in preparation for submission to the peer-reviewed Journal Isotopes in Environmental and Health studies as:

THE COMPLEXITY OF STABLE ISOTOPE INTERPRETATION IN HIGH-CONTINENTAL SYSTEMS - A MALACOLOGICAL STUDY FROM THE SOUTHERN CAUCASUS

Authors: Christiane Richter1, Daniel Wolf1, Stefania Milano2, Frank Walther3, Markus Fuchs4, Lilit Sahakyan5, Dominik Faust1

1 Dresden University of Technology, Helmholtzstraße 10, 01069 Dresden 3 Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany

3 University Hamburg, Centrum für Naturkunde, Martin-Luther-Platz 3, 20146 Hamburg,

Germany

4 Justus-Liebig-University Giessen, Senckenbergstr. 1, 35390 Gießen, Germany

5 National Academy of Sciences of the Republic of Armenia, Baghramyan Ave. 24a, 0019 Yerevan, Armenia

Abstract. Loess-palaeosol sequences in the Armenian highlands provide insight into the climatic and environmental history of the Quaternary and are excellent archives for studying climate evolution during glacial-interglacial cycles. For this continental environment, we investigated embedded gastropod assemblages and stable isotope signals (18O and 13C, V- PDB) of the terrestrial gastropod Kalitinaia crenimargo over the past 200 ka. The mean 18O signals vary between -0.5 and -4.1‰, whereas mean 13C signals fluctuate between -3.6 and -7.5‰. While species compositions indicate arid glacial and more humid interglacial and interstadial phases, the isotope signals of the gastropod shells do not show a consistent pattern related to the succession of lithofaciestypes or gastropod compositions, respectively. Although disentangling the major influencing factors seems challenging, 18O signals of these gastropod shells point to changes of the predominant source regions of precipitation and the trajectory of

136 the rain-bearing air masses. They can thus provide valuable information on atmospheric patterns related to glacial interglacial cycles.

5.1 INTRODUCTION

Quaternary loess-palaeosol sequences as archives for glacial-interglacial climate fluctuations have been of interest to the palaeo-environmental scientific community for many years (e.g. Zöller & Semmel, 2001, Meszner et al., 2011, Zeeden et al., 2018, Obreht et al., 2019, Rousseau et al., 2020). Especially in recent times of rapid climate change, it is becoming increasingly important to understand causal relationships between climatic factors and ecosystems. In this study, we investigate these relationships based on loess-palaeosol sequences of the Armenian highlands. This region is particularly suitable for appropriate analyses, as its unique natural history created a high number of endemic species and highly sensitive ecosystems. The investigated loess-archives exhibit a high chronological resolution and completeness. They include several pedocomplexes, comprising multiple glacial- interglacial cycles (Wolf et al., 2016). To derive information on ancient ecosystems and environmental conditions related to loess-palaeosol sequences, Quaternary gastropods proved to be particularly suitable (Ložek, 1990, Preece et al., 1990, Limondin-Lozouet & Gauthier, 2003, Moine et al., 2005, 2014, Marković, et al, 2006, Alexandrowicz et al., 2014, Rousseau et al., 2007, Horsák et al., 2019, Sümegi, 2019). First detailed stratigraphic studies on Quaternary gastropods in the Armenian highlands by Richter et al. (2020) showed for the investigated sites that semidesert shrub-steppe ecosystems associated to glacial times alternated with steppe to forest-steppe ecosystems with moister conditions during interglacial and interstadial periods, respectively. In order to ensure a multiproxy approach and to obtain complementary information about the palaeo-environmental conditions, we additionally investigated the stable isotopic composition of imbedded gastropod shells. Though numerous studies show that 18O and 13C signals are valuable proxies to reconstruct past environments, stable isotope interpretations on terrestrial gastropods have rarely been applied to sedimentary archives yet and comprise only few studies such as by Kehrwald et al. (2010), Colonese et al. (2011), Yanes et al. (2011), Prendergast et al. (2016) and Milano et al. (2018). While stable oxygen isotope signals in gastropod shells are assumed to provide hydrological information (i.a. Lécolle, 1985, Balakrishnan & Yapp, 2004), it is expected that 13C signals indicate the snail nutrition, potentially disclosing information on the palaeo-vegetation (Stott, 2002, Metref et al., 2003, Colonese et al., 2014). The aim of this study is to test the applicability of isotope analysis to these continental loess archives in the Armenian highlands and to derive additional information about the environmental history of the investigated Caucasian archives.

137

5.2 GEOGRAPHICAL SETTING AND STATE OF KNOWLEDGE

The study area is located at the north-eastern flanks of the Lesser Caucasus close to the Armenian village of Achajur (Fig. 1). The investigated loess sections Achajur (m. a.s.l., 41°00’16’’ N, 45°09’22’’ E) and BL (680 m. a.s.l., 41°01’32.9’’ N, 45°10’01’’ E) are located in the catchment of the Aghstev river in the province of Tavush. The Aghstev river drains into the Azerbaijani Kura Basin, which is part of the tectonic depression between the Lesser Caucasus and the Greater Caucasus. The present climate in the study area is characterised by a humid temperate climate with hot summers and moderate winters. The average annual precipitation amounts 507mm. The mean annual temperature is 11.1°C, with the highest monthly average of 22.3°C in summer and the lowest monthly average of -0.1°C in winter. Since the Pleistocene, the Greater Caucasus climatically separated the Lesser Caucasus foothills from cold winds from the north, causing parts of the Kura depression to become a protected retreat during glacial periods (see Zazanashvili et al., 2004). The Likhi range (see Fig. 1) separates the study area from humid air masses from the Black Sea (Lydolph, 1977), which currently leads to higher aridity in the Kura basin.

The studied sequences are composed of loess and tephric material, partly overprinted by

Fig. 5.1 Topographic map of the study region, with the red rectangle marking the study area (modified from maps-for-free.com).

138 pedogenesis or relocation processes. The sequences were subdivided into five sub- sequences. The stratigraphic order of lithological units and pedocomplexes in the two profile sections is quite similar. A detailed description of the Sevkar and BL sections is already published in Wolf et al. (2016). In order to facilitate the assessment of the presented gastropod results against the background of stratigraphic features, a brief overview of the revised stratigraphic succession is given in Figs. 5.3 & 5.4.

Stable oxygen isotopes

Studies by i.a., Lécolle (1985) and Zanchetta et al. (2005) showed that the 18O signals in gastropod shells correlate with mean annual 18O signals of the local precipitation, while 18O in precipitation, in turn, is a product of e.g., the isotopic composition of the moisture source (source effect), temperature effect, continentality effect, amount effect and altitude effect (e.g., Dansgaard, 1964, Rozanski et al. 1993, Field, 2010). Moreover, there can be a parallel bias by evaporation processes leading to an enrichment of 18O and thus more positive 18O signals of the gastropod shells (see Goodfriend & Magaritz, 1987, Zanchetta et al., 2005). Evaporation rates, in turn, depend on the relative humidity (see e.g., Yapp, 1979), wind movement, temperatures and seasonal patterns (see Magaritz & Heller, 1983).

Stable carbon isotopes

Studies i.a. by Stott (2002), Metref et al. (2003), Liu et al. (2007) and Yanes et al. (2013) showed that 13C signals of terrestrial gastropod shells are primarily a function of the isotopic composition of the gastropod nutrition. Thus, if the food spectrum of the species is known, the 13C signal can potentially be used to derive palaeo-vegetation. It has been demonstrated for lands snails of the family Geomitridae, that 13C shell signals allow us to derive the proportion of ingested highly xerophilous plant species (C4 and CAM) compared to less xerophilous and mesophilous plant species (C3) (Goodfriend & Magaritz, 1987, Goodfriend, 1990). This proportion can be used as proxy for humidity conditions (see Goodfriend, 1990, Prendergast et al., 2015). This principle is based on the different metabolism of these plant groups, causing different ratios of 13C to 12C in the respective plant species. Hence, the 13C signal in plants can be used as an indicator for their long-term water use efficiency (Ehleringer, 1989, Marshall et al., 2007). However, for the interpretation of the signals, it is also important to be aware of bias from other carbon sources for the shell composition (atmospheric CO2 and ground-derived carbonates) and individual nutritional preferences of the respective species.

139

The terrestrial gastropod Kalitinaia crenimargo

Stable isotope measurements in this study were conducted on the terrestrial gastropod Kalitinaia crenimargo (Pfeiffer, 1848). This species is endemic to the Caucasus region where it is widespread and locally abundant in xerophilous habitats. It belongs to the subfamilly Helicinae within the family Geomitridae (Neiber et al., 2017). The species lives mainly in Artemisia semideserts and phryganoid shrub vegetation (Akramowski, 1976, own observations). The diet of Kalitinaia crenimargo has not been studied in detail. However, we observed living specimens on dead plant remains during wet weather conditions. This is a clear indication that this species has the same food preferences as related species. Studies on Cernuella virgata (Butler, 1972) and Helicella itala (Schmid, 1934, Frömming, 1954) revealed that the snails avoid to feed on living plants and instead eat plant remains in various stages of decomposition as well as the excrements of herbivorous mammals (e.g. sheep or rabbit). Another related species, Xerolenta obvia, consumed soft plant parts as well as soaked dead plant remains (Schmid, 1930).

Biostratigraphic background

Richter et al. (2020) investigated fossil gastropod assemblages and species compositions across time for multiple loess-palaeosol sequences in the Armenian highlands. Based on these gastropod compositions, an ecostratigraphy for the Quaternary deposits of the study region was developed. The gastropod assemblages contained species of different ecological groups and with different moisture requirements, with significant alternations of species compositions associated with pedocomplexes and pure loess units, respectively. Unmodified loess layers, that most probably formed during glacial phases according to available age information (see luminescence dates in Fig. 3), contain snail species of the shrub- and shortgrass steppes, indicating semiarid to arid conditions. In contrast, pedocomplexes include species that inhabit the highgrass- to forest steppe biomes, thus indicating increased mean annual precipitation amounts. The distribution of gastropods across the BL sequence in combination with their ecological assignment is shown in the mollusc diagram Fig. 3. The mollusc spectrum in Fig. 6 shows the percentage of the ecological groups represented in each assemblage (also see Richter et al., 2020 for the complete dataset).

140

Tab. 5.1 Description of the lithofaciestypes of sections BL and Achajur.

Lithofacies types Abbreviation Description . Interpretation ….

S Dark-brown to blackish coloured loam to clay with clay Palaeosol contents predominantly between 35 and 58% and 0.2 to 1.2% organic matter (Corg); partly containing reworked clay pepples as well as insitu pedogenic features such as crumbly to prismatic aggregates, pedogenetic carbonate enrichments (calcareous pseudomycelia), bioturbation, root channels and numerous krotovinas

WS Weakly weathered, brownish coloured loamy silt to loam, Weak soil formation insitu pedogenesis is indicated by gradually increasing loam content to the top

L Silt, containing carbonate and volcanic glasses Loess

V Light bluish coloured material, predominantly volcanic Tephra glasses

C Loam with incorporated dark rounded clay pepples Relocated colluvial material

F Homogenous clayey loam with sharp boundaries to the Strongly weathered loess adjacent layers

141

Fig. 5.2 Mollusc diagram illustrating the species composition and abundances for gastropods of the BL section. Lithofaciestypes are described in Table 5.1. Malacozones are depicted according to the legend in Fig. 4. Coloured brackets at the top show the allocation of each taxon to ecological categorisations; the arrow bar visualises the implication on the associated moisture regime. We refer to the digital version for coloured figures.

142

5.3 METHODS

5.3.1 Fieldwork

Fossil samples

Based on previous field campaigns, we chose the most representative and complete profiles “Achajur” and “BL” for mollusc analyses. For the Achajur profile, 38 sediment samples were taken in accordance with lithological units (Fig. 4) with a volume of 10 l sediment each over a thickness of 13 meters. Mollusc data of BL are based on Richter et al. (2020) and were taken with similar sample procedure. They comprise 81 samples taken over a thickness of 28 metres.

Sampling for modern shells

Three extant populations of Kalitinaia crenimargo have been sampled between 2011 and 2014 in the wider study area (Fig. 7, see Tab. 2 for details). Additional shell material and tissue is stored in the collection of the Zoological Museum Hamburg (ZMH).

5.3.2 Laboratory Analyses

Extraction of mollusc shells

All samples were wet sieved to the fraction > 500 µm to extract the shells. Due to the high aggregation of grains related to clay contents of more than 60%, the sediment was agitated for 3 to 10 hours before sieving. Extracted shells were determined and quantified using a stereomicroscope with 20 to 40 times magnification. Complete shells and shell fragments (offset against each other and amounted to the related number of broken individuals) were quantified as described in Richter et al. (2020).

Stable isotope analysis

For all the samples with sufficient shell material, we extracted shells for the species Kalitinaia crenimargo, which was most widely represented among the sequence. Accordingly, we analysed 14 samples from the BL profile and 20 samples from the Achajur profile by measuring two to four individual shells per sample. For isotope measurements, the gastropod shells were cleaned in an ultrasonic bath and afterwards treated with H2P2 10 vol % to remove residual organic matter. Subsequently, the shells were rinsed with tap water. They were air dried and afterwards powdered with an agate mortar and pestle. The isotopic analyses were performed on the carbonate powder using a Thermo Fisher 253 Plus gas source isotope ratio mass spectrometer connected to a Kiel IV automated carbonate preparation device at the Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology. The isotope values were reported in per mil (‰) relative to the Vienna Pee-Dee Belemnite (VPDB)

143 standard based on IAEA-603 calibrated Carrara marble (18O=−1.64‰, 13C=+1.87‰). The average precision (1σ) determined was better than 0.1‰ for both 18O and 13C.

5.4 RESULTS

5.4.1 Gastropod record Achajur

The gastropod fauna of the investigated sections Achajur and BL include at least 20 terrestrial species of the following taxa: Aegopinella indet. (Lindholm, 1927), Cecilioides acicula (Müller, 1774), Chondrula tridens (Müller, 1774), Gibbulinopsis interrupta (Reinhardt in Martens, 1876), Gibbulinopsis signata (Mousson, 1873), Imparietula indet. (Lindholm, 1925), Kalitinaia crenimargo (Pfeiffer, 1848), Multidentula pupoides (Krynicki, 1833), Pupilla bipapulata (Akramowski, 1943), Pupilla kyrostriata (Walther & Hausdorf, 2014), Pupilla inops (Reinhardt, 1877), Pupilla aff. poltavica (Boettger, 1889), Pupilla triplicata (Studer, 1820), Stenomphalia selecta (Klika, 1894), Truncatellina callicratis (Scacchi, 1833), Truncatellina cylindrica (Férussac, 1807), Vallonia costata (Müller, 1774), Vallonia pulchella (Müller, 1774), Vitrea pygmaea (Boettger, 1880), Xeropicta derbentina (Krynicki, 1836). Species compositions and abundances for every sample are depicted in Figs 2 and 3. A detailed protocol of the data is provided in the supplementary material Tables 5.3 and 5.4.

5.4.2 Stable isotope results

The 13C and 18O results of the gastropod analyses are illustrated in Figs. 4 and 5, while the datasets for modern signals are given in Table 2 and for the palaeosamples in the supplementary data Table 3. For both profiles, the mean standard deviation is less than 1/4 of the variance for both 13C and 18O signals.

The 18O signals of the Achajur profile show mean values between -1.3 and -3.8‰ (with a variance of 2.5‰) and mean standard deviation of 0.6‰). For the BL section we have 18O mean values between -0.5 and -4.1‰ (variance of 3.6‰) with a mean standard deviation of 0.5‰. There is a significant difference between the sample medians across the profile (Kruskal-Wallis test p=0.0008 for BL and p=0.009 for AJ). Furthermore, we found a statistically significant difference between the medians of 18O signals for samples that relate to gastropod assemblages with mesophilous to hygrophilous species (malacozones A, B, C, E & G; e.g., samples AJ-2, AJ-5, AJ-7, AJ-10, AJ-11, AJ-16, AJ-23 to AJ-27 and BL- BL6, BL-7, BL-18 and BL-19) compared to exclusively xerophilous species assemblages (Kruskal-Wallis test: p=0.017 for BL and p=0.012 for AJ). Accordingly, we have a trend in both sediment sequences for more negative 18O signals to be related to exclusively xerophilous gastropod communities.

144

Stable carbon isotope results comprise 13C signals between -3.6 and -6.5‰ (with a variance of 2.9‰ and a mean standard deviation of 0.7‰) for the BL profile and between -5.7 and -7.5‰ (with a variance of 1.7‰ and a mean standard deviation of 0.4‰) for the AJ profile. Sample AJ-14 was excluded for further interpretations due to its extremely high standard deviation, supposably due to measurement failure. According to a Kruskal-Wallis test, there is a statistically significant difference between the sample medians across the AJ profile (p=0.008) but not across the BL profile (p=0.101). Accordingly, we cannot find a consistent pattern between 13C of Kalitinaia crenimargo shells and different units of the sediment

Fig. 5.3 Mollusc diagram illustrating the species composition and abundances for gastropods of the Achajur section. Malacozones are depicted according to the legend. Coloured brackets at the top show the allocation of each taxon to ecological categorisations; the arrow bar visualises the implication on the associated moisture regime. We refer to the digital version for coloured figures. sequences.

145

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147

Tab. 5.2 Site-specific information and 18O and 13C results for the modern gastropod samples. All samples refer to the gastropod species Kalitinaia crenimargo.

Sample ID R1 R2 R3

Coll.-Nr. ZMH 86136 ZMH 1004548 ZMH 101217

Coordinates 41°50'23"N 44°44'07"E, 41°56'56"N 44°25'15"E, 40°51'06"N 45°03'43"E, 620 m a.s.l. 600 m a.s.l. 1590 m a.s.l.

Locality Georgia, Jvari Monastery Georgia, N of Kaspi Armenia, mountain ridge W of Ijevan

Date and collector 3 Oct. 2011, F. Walther & 20 Sep. 2012, F. Walther 7 Jul. 2014, F. Walther M.T. Neiber leg. & R. Köhler leg. & M.T. Neiber leg.

δ18O Shell 1 -3,092 -1,54 -1,109 Shell 2 -3,857 -1,998 -1,907 Shell3 -1,527 -2,296 Mean -2,825333333 -1,944666667 -1,508 Stddev 1,187669286 0,380811414 0,564271211

δ13C Shell1 -8,98 -6,877 -7,842 Shell2 -9,397 -5,31 -8,809 Shell3 -7,779 -7,583 Mean -8,718666667 -6,59 -8,3255 Stddev 0,84006091 1,163361079 0,683772257

5.5 DISCUSSION

5.5.1 Signals in modern snail shells

In order to compare the palaeo-isotopic 18O signals, we carried out a comparative study on modern gastropod shells setting them in relation to 18O signals of the modern precipitation. In order to rule out the influence of taxonomic differences due to different species-specific types of metabolism, behaviour and activity phases, all measurements were limited to Kalitinaia crenimargo. For the 18O signals of Kalitinaia crenimargo shells in this continental Caucasian environment, we assume two activity periods in spring and autumn. In contrast to other Geomitrids, the species rests during the dry hot summers and dry cold winters buried in sand, gravel or debris at the base of shrubs (own observations). As the main growth time is in spring,

148 we compare the shell signals to modelled 18O precipitation signals of April, extracted from the Waterisotopes Database (2017). Based on these data, more negative 18O precipitation signals relate to higher altitudes (Fig. 7). In numerous studies (e.g., by Yanes et al., 2018), gastropod shells similarly reflect this relationship as they mainly use oxygen from absorbed precipitation for building their carbonate shells. For example, Lécolle (1985) evidenced a depletion of 4 to 5‰ at 18O per 1000 m rise in elevation for different species of the family Helicidae. Contradictory, our results show an inverse relationship, with more positive 18O shell signals for higher altitudes. This correlation is also in contradiction with the expected amount effect (increasing rainfall at higher altitudes usually causes more negative 18O signals) and an expected 18O signal decreasing with altitude due to decreasing evaporation (increase in orographic humidity should lead to higher relative humidity and thus to lower evaporation rates). Nevertheless, the patterns described above do not seem to dominate the 18O signals of our modern shells. An explanation could be a parallel to the observations by Lécolle (1985), who found less negative 18O values at altitudes above 1200 m a.s.l., not showing the usual altitude effect either. They explained this effect by the fact that 18O precipitation still correlates with the altitude effect even above 1200 m, but that these heights lead to extension of the gastropod hibernation period. They assumed that only the rain signal of the average growing season (activity phase of the gastropod) is incorporated into the 18O of the shells.

The most negative 18O rain values that are related to winterly precipitation are missing, thus making the signals more positive. However, in our case not only a weakened ratio but an inverse relation between altitude and 18O of the shells is observed, making this “altitude phenomenon” unlikely to be the only reason for the measured values. Brittingham (2019) measured 18O in precipitation at different sites of the Armenian highland and the Caucasus region and equally found that 18O in precipitation does not correlate with elevation nor with the amount effect. Instead, they found a statistically significant correlation of 18O to the local temperature at the place of rainfall. The mean change of 18O was 0.47‰/°C. According to this consideration, more positive 18O signals would be expected at higher temperatures. The 18O shell signal at the Armenian location west of Ijevan (sample R3) at 1590 m a.s.l. is 1.3‰ more positive than of the location at the Ijvari Monastery at 620m a.s.l. (sample R1) and would therefore indicate warmer temperatures. In contrast, the average April temperatures in alpine regions should be significantly colder compared to lower elevations in the study area. So it is still unclear how these modern signals should be interpreted. We assume that local atmospheric patterns and the relief influence the predominant air masses that are related to different 18O signals. The palaeo-samples refer to almost constant elevations. Based on recent results, however, we propose that fluctuations in the 18O signals of the palaeo-samples

149 are less dominated by an evaporational influence, but rather reflect local temperatures or the 18O enrichment of the source air masses, respectively.

Fig. 5.6 Red arrows show the studied sites for modern gastropod collections of Kalitinaia crenimargo. Coloures refer to average monthly δ18O signals of precipitation for April and are taken from the Waterisotopes database of the University of Utah and are based on models by Bowen & Wilkinson (2002) and refined by Bowen & Revenaugh (2003) and Bowen et al. (2005).

5.5.2 Stable oxygen isotopes in a highly continental setting – the difficulty of the interpretation of δ18O of fossil gastropod shells

Malaco-ecological analyses on Caucasian loess-palaeosol sequences by Richter et al. (2020) showed that gastropod assemblages of glacial phases were dominated by xerophilous species, while assemblages associated to pedocomplexes additionally contained meso- and hygrophilous species. In this context, it should be noted that there is no complete congruence of pedomorphic lithological units and the presence of gastropod assemblages that indicate moister conditions. A major problem here is the difficulty of identifying and distinguishing in- situ pedogenesis and relocated soil sediments. Consequently, the embedded taphocoenoses may be a mixture of allochthonous pre-depositional biocenoses and in-situ post-depositional biocenoses (thanatocenoses), which might have been related to different environmental conditions. Accordingly, the general pattern of loess deposits being associated with xerophilous assemblages versus pedocomplexes, assumedly related to morphodynamic stability phases and the presence of mesophilous assemblages, may be partially deviating. In this context, we suspect a significant disturbance by relocation processes, especially for the Achajur profile. We have therefore decided to base the isotope interpretation of our gastropod shells primarily on the eco-stratigraphy, rather than on the lithofacies of the samples. If we

150 compare the stable oxygen isotope signals with the gastropod associations from Richter et al. (2020) and this study, there is a weak trend of less depleted signals for samples with exclusively semidesert species and more enriched signals for samples that include mesophilous to hygrophilous species. As suggested by a couple of isotope studies, 18O signals of terrestrial gastropod shells basically reflect 18O precipitation signals modified by evaporation (see i.a. Goodfriend et al., 1989, Balakrishnan & Yapp, 2004, Colonese, 2017), with the latter being influenced e.g., by relative humidity, ambient temperatures and wind strength. In the case of a significant bias by evaporation, we would expect more positive 18O signals related to dryer glacial age conditions, since higher evaporation rates cause the enrichment of the heavier oxygen-18 isotope in both, fallen precipitation and the hemolymph of the gastropod itself (Goodfriend & Magaritz, 1987). Both effects would increase the 18O signals in the shell. In contrast, we observe more depleted 18O signals in the majority of loess samples. Accordingly, we have more positive 18O shell signals in a high number of samples with hygrophilous species (e.g., samples BL-5, BL-6, BL-18, BL-19, AJ-11, AJ-23 to AJ-25). The available data thus suggest that evaporation was not the predominant factor for fluctuations in 18O across time and that the stable oxygen isotope signals in our study area were biased by at least one other factor.

More negative 18O signals in the gastropod shells associated to dryer phases might be explained by either source or temperature effect. Since rain events are predominantly caused by atmospheric temperature decreases of the rain-bearing air masses, 18O of the precipitation as well as the 18O signals of the marine sea surface water simplified reflect average annual global air temperatures (see Fig. 7). Lécolle (1985) found a strong correlation between the 18O signals of gastropod shells and the mean annual temperatures of the site under study. They calibrated mean 18O shell values for an agglomeration of several species for different locations and disclosed a mean shift of 3 to 5‰ for 7°C in different climates, corresponding to about 0.5‰ per degree Celsius. The highest variation of 18O signals in our study is shown for the BL section with values between -0.5 and -4.1‰ and thus a variance of 3.6‰ (mean standard deviation of 0.5‰). If we attribute the 18O changes exclusively to fluctuations in the local temperatures of our site, we could use the study of Lécolle (1985) and assume our 18O shift of 3.6‰ to correspond to a temperature shift of 7°C, with the lowest temperatures being related to loess deposits and the highest temperatures to pedocomplexes. However, apart from major species-specific differences in fractionation and behaviour, we should also be aware of the fact that terrestrial gastropods record only the conditions during the time of snail activity (Goodfriend et al., 1989).

Other authors such as Kehrwald et al. (2010) suggest that the direct influence of temperature

151 on 18O signals of terrestrial gastropod shells is of minor importance and that 18O shell signals are instead primarily a function of other effects that determine the 18O signals of the precipitation (see Fig. 7). Accordingly, the 18O signals of source water bodies for precipitation do not homogenously follow mean annual temperature patterns but rather differ locally (see Fig. 7). Due to e.g., different evaporation rates, freshwater supply, salinities etc. of the source water bodies, 18O precipitation also depends on specific source regions and the trajectory of the rain-bearing air masses (see e.g. Kehrwald et al., 2010). The modern signal of the surface water is around 2‰ for the Mediterranean Sea and around -2.5‰ for the Black sea (LeGrande and Schmidt, 2006). Thus, for our study area, the origin of the precipitation would strongly influence its 18O signals. Brittingham et al. (2019) assumed, that 18O in precipitation of the Armenian highlands is related to the intensity of the North Atlantic Oscillation (NAO), influencing the strength and location of Northern Hemisphere midlatitude westerlies. Negative (weakened) NAO phases are associated with weakened westerlies, which allows precipitation from the Mediterranean and southerly sources enriched in heavy isotopes to penetrate into the Armenian Highlands. In contrast, positive NAO phases seem to be associated with stronger westerlies bringing more negative precipitation from the Black Sea. This relationship was described as significant during the winter and spring months (Brittingham, 2019), which also includes the period that is recorded by the gastropod shells.

Extending this relationship to glacial-interglacial cycles at the Armenian highlands is difficult, since atmospheric circulation patterns during glacial periods differ strongly compared to interglacial stages. However, one could expect weakened westerlies during glacial periods amplified by a stronger influence of the Siberian cold high-pressure system (Obreht et al., 2017). This could have caused more positive 18O precipitation from the Mediterranean region or the Caspian Sea entering the Armenian highlands.

However, the isotopic compositions of our Caucasian gastropod archives point to more positive 18O signals related to pedocomplexes. This is contrary to the general assumption for the Central European loess-palaeosol sequences that phases of loess deposition are related to glacial periods and, vice versa, that geomorphodynamically stable phases of soil formation coincide with interglacial/interstadial periods. However, we have to be aware of different process dynamics related to our deposits, as loess deposits in our study area are associated with gastropod communities that indicate no classical periglacial conditions (see Richter et al., 2020).

However, if we base this temporal allocation, the present isotope values may also be explained by differences between glacial and interglacial periods, which may have fundamentally reweighted the influencing factors that dominate today. Such glacial versus

152 interglacial/interstadial age differences may comprise different 18O signals of potential source waters, alterations of the continentality effect, different seasonalities influencing spring temperatures and the duration of gastropod activity phases, changed seasonalities of atmospheric patterns, different rain amounts (while higher rain amounts, in turn, would influence amount effect and evaporation). In addition, the marine source signals for 18O precipitation fluctuate with changing ice cap volumes and would lead to enrichment in 18O in the atmosphere of glacial compared to interglacial and interstadial phases. While for some oceanic settings this relation could be found to dominate the 18O signals in gastropod shells (Richter et al., subm.), this correlation cannot be approved in our continental Caucasian archives, as more negative 18O shell signals tend to be related to loess deposits of suspected glacial phases. Accordingly, we suggest that the interpretation of 18O signals in gastropod shells is highly dependent on the environment under investigation and, due to the complexity of the influencing factors, should be treated with great caution.

Based on our modern and Quaternary datasets, however, we assume that the source region and trajectory of rain bearing airmasses have played a decisive role. There may have been a fundamentally different compilation between prevailing winds for the study area, e.g. a declining influence of southerly winds related to colder phases.

Fig. 5.7 The figures show the correlation between δ18O in precipitation (A), δ18O of the surface seawater (B) and mean annual temperatures of both surface seawater and air (C) in a global context. In Fig. (B) we can additionally see the effect of locally specific deviations of surface water δ18O signals from the above patterns, especially for the Mediterranean and Black Sea. More detailed information on the maps is given in the following: (A) Global amount-weighted δ18O of annual precipitation. The map shows a regionalized cluster-based water isotope prediction (RCWIP) approach, based on the Global Network of Isotopes in Precipitation (GNIP) by Terzer et al. (2013). The legend is δ18O in ‰ relative to the VSMOW-SLAP scales. (B) Global mean annual δ18O of surface seawater from the Global Seawater Oxygen-18 Database. The dataset is 18 described in LeGrande and Schmidt (2006) and uses regional δ O - salinity relationships and PO4 to define water mass boundaries.Source: https://data.giss.nasa.gov/o18data/ - the originak map is supplemented with additional values for the Black sea (from the same dataset) (C) Global mean annual temperatures (air and surface seawater). This map was produced by Rohde, R. A. by combining land-surface temperature data sets from New et al. (2002) with sea-surface temperature data sets by Reynolds et al. (2002) and Reanalysis data by Kalnay et al. (1996). Source: http://berkeleyearth.org/archive/land-and-ocean-data/).

153

154

5.5.3 δ13C signals in Kalitinaia crenimargo – what do nutritional changes tell us?

To assess whether 13C and 18O signals of the snail shells reflect similar environmental factors, we examined the correlation between the two proxies. The Pearson correlation coefficient in combination with a t-test showed that there is no statistically significant relationship between 13C and 18O for the individual profiles. If 13C signals of K. crenimargo shells reflect residues of C3 vs. C4 plants ingested as leaf litter, more negative 13C signals would correspond to a higher abundance of C3 plants, indicating a higher moisture availability. However, there is no consistent pattern between the isotopic composition of the shell carbon and the succession of lithological units or the ecological affiliation of associated species compositions, respectively. As we assume that Kalitinaia crenimargo feeds on plant remains in various stages of decomposition as well as on excrements, we reason that different fractionation processes related to these types of material conversion might have modified the original 13C signals of the living plants. Additionally, it has not been investigated whether Kalitinaia crenimargo ingests all plants types in equal proportions, or preferentially feeds on either C3 or C4/CAM plants. Accordingly, further species-related studies on the dependence of 13C shell signals and the present vegetation, dietary preferences, as well as a higher sample volume could help to improve the applicability of 13C interpretations for the examined archives.

5.6 CONCLUSION

Loess-palaeosol sequences in the Armenian highlands were investigated regarding their gastropod compositions and stable carbon and oxygen isotope signals of the terrestrial gastropod Kalitinaia crenimargo.

The influences on 13C and 18O signals from gastropods and palaeo-precipitation are still insufficiently understood and there is a need of further studies, in particular to advance the calibration of the influencing factors. Thus, we suggest caution in the interpretation of isotope signals and furthermore a comparison with the information obtained from the composition of the gastropod communities, which can serve as a reliable calibration tool.

We found, that 18O signals of modern gastropod shells showed more positive values related to higher altitudes. Accordingly, they do not reflect the common altitude effect, which coincides with results by Brittingham et al. (2019) for 18O precipitation signals at the Armenian highlands. Accordingly, we assume local atmospheric patterns and relief to influence the predominant air masses related to different 18O signals of the precipitation.

We observed more depleted 18O signals in the majority of samples with exclusively

155 xerophilous gastropod species and more positive 18O shell signals in a high number of samples including mesophilous to hygrophilous species. Based on our stable isotope results and ecological information derived from species compositions of the investigated lithological units, we suggest that alterations in the 18O shell signals may mainly reflect alternating 18O signals of the precipitation, which, in turn, are assumed to be related to changes of the predominant source regions and trajectories of the rain-bearing air masses. Based on our palaeo-record and modern isotope studies from Brittingham et al. (2019) for the Armenian highlands, we suggest, among other possible explanations, a declining influence of southerly airmasses at our study site, leading to more negative 18O signals during phases of loess deposition.

5.7 REFERENCES

Alexandrowicz W.P., Łanczont M., Boguckyj A.B., Kulesza, P. & Dmytruk, R. 2014: Molluscs and ostracods of the Pleistocene loess deposits in the Halychsite (Western Ukraine) and their significance for palaeoenvironmentalreconstructions. Quaternary Science Reviews 105, 162- 180.

Balakrishnan, M. & Yapp, C. J. 2004: Flux balance models for the oxygen and carbon isotope compositions of land snail shells. Geochimica et Cosmochimica Acta, 68(9), 2007-2024.

Bowen G. J. & Wilkinson B. 2002: Spatial distribution of δ18O in meteoric precipitation. Geology 30(4), 315-318.

Bowen G. J. & Revenaugh J. 2003: Interpolating the isotopic composition of modern meteoric precipitation. Water Resources Research 39(10), 1299.

Bowen G. J., Wassenaar L. I. & Hobson K. A. 2005: Global application of stable hydrogen and oxygen isotopes to wildlife forensics. Oecologia 143, 337-348.

Brittingham, A., Petrosyan, Z., Hepburn, J. C., Richards, M. P., Hren, M. T. & Hartman, G. 2019: Influence of the North Atlantic Oscillation on δD and δ18O in meteoric water in the Armenian Highland. Journal of Hydrology 575, 513-522.

Butler, A. J. 1972: The food of the terrestrial snail Helicella virgata (da Costa) in South Australia. PhD Thesis, 236 pp., University of Adelaide.

156

Colonese 2017: Stable isotope ecology of terrestrial gastropod shells. In: Allen, M. J. (Ed.) 2017: Molluscs in archaeology: methods, approaches and applications (Vol. 3). Oxbow Books.

Colonese, A. C., Zanchetta, G., Drysdale, R. N., Fallick, A. E., Manganelli, G., Vetro, D. L., Martini, F. & Di Giuseppe, Z. 2011: Stable isotope composition of Late Pleistocene-Holocene Eobania vermiculata (Müller, 1774) (Pulmonata, Stylommatophora) shells from the Central Mediterranean basin: Data from Grotta d’Oriente (Favignana, Sicily). Quaternary International 244(1), 76-87.

Colonese, A. C., Zanchetta, G., Fallick, A. E., Manganelli, G., Cascio, P. L., Hausmann, N., Baneschi, I. & Regattieri, E 2014: Oxygen and carbon isotopic composition of modern terrestrial gastropod shells from Lipari Island, Aeolian Archipelago (Sicily). Palaeogeography, Palaeoclimatology, Palaeoecology 394, 119-127.

Dansgaard, W. 1964: Stable isotopes in precipitation. Tellus 16, 436-468.

Ehleringer, J. R. 1989: Carbon isotope ratios and physiological processes in arid land plants. In: Rundel, P. W., Ehleringer, J. R. & Nagy, K. A. (Eds.): Stable isotopes in ecological research. Ecological Studies 68, 41-54.

Field, R. D. 2010: Observed and modeled controls on precipitationδ18O over Europe: From local temperature to the Northern Annular Mode. Journal of Geophysical Research: Atmospheres, 115(D12).

Frömming, E. 1954: Biologie der mitteleuropäischen Landgastropoden. Berlin, Duncker & Humblot.

Goodfriend, G. A. & Magaritz, M. 1987: Carbon and oxygen isotope composition of shell carbonate of desert land snails. Earth and Planetary Science Letters 86(2), 377-388.

Goodfriend, G. A., Magaritz, M. & Gat, J. R. 1989: Stable isotope composition of land snail body water and its relation to environmental waters and shell carbonate. Geochimica et Cosmochimica Acta 53(12), 3215-3221.

Goodfriend, G. A. 1990: Rainfall in the Negev Desert during the middle Holocene, based on

157

13 C of organic matter in land snail shells. Quaternary Research 34(2), 186-197.

Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Leetmaa, A., Reynolds, R., Jenne, R. & Joseph, D. 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bulletin of the American Meteorological Society 77(3), 437–471.

Kehrwald, N. M., McCoy, W. D., Thibeault, J., Burns, S. J., & Oches, E. A. 2010: Paleoclimatic implications of the spatial patterns of modern and LGM European land-snail shell δ18O. Quaternary Research 74(1), 166-176.

Horsák M., Limondin-Lozouet N., Jurickova L., Granai S., Horackova J., Legentil C. & Lozek V. 2019: Holocene succession patterns of land snails across temperate Europe: east to west variation related to glacial refugia, climate and human impact. Palaeogeography, Palaeoclimatology, Palaeoecology 524, 13-24.

LeGrande, A.N. & Schmidt, G. A. 2006: Global gridded data set of the oxygen isotopic composition in seawater. Geophysical Research Letters 33, 1–5.

Lécolle, P. 1985: The oxygen isotope composition of landsnail shells as a climatic indicator: applications to hydrogeology and paleoclimatology. Chemical Geology: Isotope Geoscience section 58(1), 157-181.

Limondin-Lozouet, N., & Gauthier, A. 2003: Biocénoses Pléistocènes des séquences loessiques de Villier-Adam (Val d'Oise, France), Etudes Malacologiques et palynologiques. Quaternaire 14(4), 237-252.

Liu, Z., Gu, Z., Wu, N. & Xu, B. 2007: Diet control on carbon isotopic composition of land snail shell carbonate. Chinese Science Bulletin, 52(3), 388-394.

Ložek, V. 1990: Molluscs in loess, their paleoecological significance and role in geochronology - Principles and methods. Quaternary lnternational 7(8), 71-79.

Lydolph, P. E. 1977: Climates of the Soviet Union. Elsevier Scientific Publishing Company, Amsterdam.

158

Magaritz, M. & Heller, J. 1983: Annual cycle of 18 O/16 O and 13 C/12 C isotope ratios in landsnail shells. Chemical geology 41, 243-255.

Marković, S. B., Oches, E., Sümegi, P., Jovanović, M. & Gaudenyi, T. 2006: An introduction to the Middle and Upper Pleistocene loess-paleosol sequence at Ruma brickyard, Vojvodina, Serbia. Quaternary International 149, 80–86.

Marshall, J. D., Brooks, J. R. & Lajtha, K. 2007: Sources of variation in the stable isotopic composition of plants. In: Lajtha, K. & Michener, R. H. 1994: Stable isotopes in ecology and environmental science. Blackwell Scientific Publications, 22-60.

Metref, S., Rousseau, D. D., Bentaleb, I., Labonne, M. & Vianey-Liaud, M. 2003: Study of the diet effect on δ13C of shell carbonate of the land snail Helix aspersa in experimental conditions. Earth and Planetary Science Letters 211(3), 381-393.

Moine, O., Rousseau, D. & Antoine, P. 2005: Terrestrial molluscan records of Weichselian Lower to Middle Pleniglacial climatic changes from the Nussloch loess series (Rhine Valley, Germany) - the impact of local factors. Boreas 34, 363-380.

Moine, O. 2014: Weichselian Upper Pleniglacial environmental variability in north-western Europe reconstructed from terrestrial mollusc faunas and its relationship with the presence/absence of human settlements. Quaternary International 337, 90-113.

Neiber, M. T., Razkin, O. & Hausdorf, B. 2017: Molecular phylogeny and biogeography of the land snail family Hygromiidae (Gastropoda: Helicoidea). Molecular Phylogenetics and Evolution 111, 169-184.

New, M., Lister, D., Hulme, M. & Makin, I. 2000: A high-resolution data set of surface climate over global land areas. Climate Research 21: 1-25.

Obreht, I., Hambach, U., Veres, D., Zeeden, C., Bösken, J., Stevens, T., Marković, S. B., Klasen, N., Brill, D., Burow, C. & Lehmkuhl, F. 2017: Shift of large-scale atmospheric systems over Europe during late MIS 3 and implications for Modern Human dispersal. Scientific Reports 7(1), 1-10.

159

Obreht, I., Zeeden, C., Hambach, U., Veres, D., Marković, S. B. & Lehmkuhl, F. 2019: A critical reevaluation of palaeoclimate proxy records from loess in the Carpathian Basin. Earth-Science Reviews 190, 498-520.

Preece, R. C. 1990: The molluscan fauna of Late Devensian loess from Reculver, Kent. Journal of Conchology 33, 295

Prendergast, A. L., Stevens, R. E., O'Connell, T. C., Hill, E. A., Hunt, C. O. & Barker, G. W. 2016: A late Pleistocene refugium in Mediterranean North Africa? Palaeoenvironmental reconstruction from stable isotope analyses of land snail shells (Haua Fteah, Libya). Quaternary Science Reviews 139, 94–109.

Reynolds, R. W., Rayner, N. A., Smith, T. M., Stokes, D. C. & Wang, W. 2002: An improved in situ and satellite SST analysis for climate. Climate 15, 1609-1625.

Richter, C., Roettig, C.-B., Wolf, D., Groh, K., Kolb, T. & Faust, D. 2019: Changes in Pleistocene gastropod faunas on Fuerteventura (Canary Islands) and implications on shifting palaeoenvironmental conditions. Quaternary Science Reviews 209, 63–81.

Richter, C., Wolf, D., Walther, F., Meng, S., Sahakyan, L., Hovakimyan, H., Wolpert, T., Fuchs, M. & Faust, D. 2020: New insights into Southern Caucasian glacial–interglacial climate conditions inferred from Quaternary gastropod fauna. Journal of Quaternary Science 35(5), 634-649.

Rousseau, D. D., Sima, A., Antoine, P., Hatté, C., Lang, A. & Zöller, L. 2007: Link between European and North Atlantic abrupt climate changes over the last glaciation. Geophysical Research Letters 34(22).

Rousseau, D.-D., Antoine, P., Boers, N., Lagroix, F., Ghil, M., Lomax, J., Fuchs, M., Debret, M., Hatté, C., Moine, O., Gauthier, C., Jordanova, D., & Jordanova, N. 2020. DO-like events of the penultimate climate cycle: the loess point of view. Climate of the Past 16, 713-727.

Rozanski, K., Araguás-Araguás, L. & Gonfiantini, R. 1993: Isotopic patterns in modern global precipitation. In: Union, A.G. (Ed.): Climate Change in Continental Isotopic Records, 1–36, American Geophysical Union Geophysical Monograph 78, American Washington DC.

160

Schileyko, A. A. 1978: Terrestrial mollusks of the superfamily Helicoidea. Fauna SSSR, Mollusca 3(6), 1-384.

Schmid, G. 1930: Zur Biologie der Helicella obvia Hartm. Archiv für Molluskenkunde 62, 57- 71.

Schmid, G. 1934: Zur Biologie von Helicella ericetorum (Müll.). Archiv für Molluskenkunde 33, 201-207.

Stott, L. D. 2002: The influence of diet on the δ13C of shell carbon in the pulmonate snail Helix aspersa. Earth and Planetary Science Letters 195(3-4), 249-259.

Sümegi, P. 2019: Refuting ideas based on a small batch of data: malacothermometry aid in the reconstruction of mean July paleo-temperatures in the Carpathian Basin for the last glacial of the Pleistocene, Archeometriai Műhely XVI/3, 143–166.

Terzer, S., Wassenaar, L. I., Araguás-Araguás, L. J. & Aggarwal, P. K. 2013: Global isoscapes for d18O and d2H in precipitation: improved prediction using regionalized climatic regression models. Hydrology and Earth System Sciences Discussions 10(6), 7351–7393.

Waterisotopes Database 2017: http://waterisotopesDB.org. Accessed 29/08/2020

Wolf, D., Baumgart, P., Meszner, S., Fülling, A., Haubold, F., Sahakyan, L., Meliksetian, K. & Faust, D. 2016: Loess in Armenia – stratigraphic findings and palaeoenvironmental indications. Proceedings of the Geologists’ Association 127(1), 29–39.

Yanes, Y., Yapp, C. J., Ibáñez, M., Alonso, M. R., De-la-Nuez, J., Quesada, M. L., Castillo, C. & Delgado, A. 2011: Pleistocene–Holocene environmental change in the Canary Archipelago as inferred from the stable isotope composition of land snail shells. Quaternary Research 75(3), 658-669.

Yanes, Y., Asta, M. P., Ibáñez, M., Alonso, M. R. & Romanek, C. S. 2013: Paleoenvironmental implications of carbon stable isotope composition of land snail tissues. Quaternary Research 80(3), 596–605.

Yanes, Y., Graves, G. R. & Romanek, C. S. 2018: Stable isotope ecology (δ18O, δ13C, δ15N)

161 of modern land snails along an altitudinal gradient in southern Appalachian Mountains, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 492, 92–103.

Yapp, C. J. 1979: Oxygen and carbon isotope measurements of land snail shell carbonate. Geochimica et Cosmochimica Acta 43(4), 629-635

Zanchetta, G., Leone, G., Fallick, A. E. & Bonadonna, F. P. 2005: Oxygen isotope composition of living land snail shells: Data from Italy. Palaeogeography, Paleoclimatology, Palaeoecology 223(1), 20-33.

Zazanashvili N, Sanadiradze G, Bukhnikashvili A, Kandaurov A, Tarkhnishvili D 2004. Caucasus. In: Mittermaier R. A., Gil P. G., Hoffmann M., Pilgrim J., Brooks T., Mittermaier C. G., Lamoreux J. & Da Fonseca G. A. B.(eds.). Hotspots revisited. Earth’s biologically richest and most endangered terrestrial ecoregions, 148–153, CEMEX/ Agrupacion Sierra Madre, Sierra Madre.

Zeeden, C., Hambach, U., Obreht, I., Hao, Q., Abels, H. A., Veres, D., Lehmkuhl, F., Gavrilov, M.-B. & Marković, S. B. 2018. Patterns and timing of loess-paleosol transitions in Eurasia: Constraints for paleoclimate studies. Global and planetary change 162, 1-7.

Zöller, L. & Semmel, A. 2001: 175 years of loess research in Germany-long records and “unconformities”. Earth Science Reviews 54 (1-3), 19-28.

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5.8 SUPPLEMENTARY MATERIAL

Tab. 5.3 Palaeo-record of the gastropod species for the section Achajur. 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Sample ID no shells no shells no 64 53 80 14 1 1 1 1 2 7 2 ------Fragments 57 43 74 1 1 1 1 2 6 2 7

------Est. Number of broken ind. Ceciloides acicula 14 13 1 1 8 ------Complete shells 71 56 82 1 1 1 1 1 3 6 2 7 ------Total 21 12 21 32 11 1 1 1 4 2 5 1 1 3 1 2 1 4 1 2 8 1 1 2 1 7 ------Fragments 15 15 1 1 1 4 1 1 1 8 1 1 1 2 1 2 1 1 1 1 1 2 1 9 6 5 ------Est. Number of broken ind. Chondrula tridens 3 1 1 ------Complete shells 15 11 10 15 1 1 1 4 1 1 1 1 1 2 2 1 2 1 1 1 1 1 2 1 6 5 ------Total 10 2 1 ------Fragments 1 1 9 ------Est. Number of broken ind. Harmozica selecta

------Complete shells 1 1 9 ------Total 132 16 19 10 10 57 34 15 25 11 12 39 6 4 2 6 6 2 1 9 7 4 1 ------Fragments 132 15 16 10 57 29 15 25 12 37 1 1 2 4 6 2 1 3 7 9 6 3 1 ------Est. Number of broken ind. Kalitinaia crenimargo 0 9 1 2 ------Complete shells 102 141 15 17 10 57 29 17 25 12 37 1 1 2 9 4 6 2 1 3 7 9 6 3 1 ------Total 1Ap 1Ap 1 1 1 ------Fragments 1 1 1 1 ------Est. Number of broken ind. Truncatellina sp.

------Complete shells 1 1 1 1 1 ------Total 11 11 1 1 1 3 ------Fragments 11 11 1 1 1 3 ------Est. Number of broken ind. Pupilla inops 10 9 4 ------Complete shells 20 26 21 2 1 1 1 7 ------Total 12 1 7 1 1 ------Fragments 12 1 7 1 1 ------Est. Number of broken ind. Gibbulinopsis interrupta

------Complete shells 12 1 7 1 1 ------Total 59 2 1 2 1 ------Fragments 59 1 1 2 1 ------Est. Number of broken ind. Pupilla kyrostriata 22 ------Complete shells 81 1 1 2 1 ------Total 1 4 ------Fragments 1 4 ------Est. Number of broken ind. Gibbulinopsis signata

------Complete shells 1 4 ------Total 27 78 34 45 11 21 26 15 12 4 1 3 7 1 5 3 3 3 9 1 5 1 1 5 1

------Fragments 27 78 34 45 11 21 26 15 12 3 1 3 7 1 5 3 2 3 5 1 5 1 1 5 1 ------Est. Number of broken ind. Pupilla spp. (including poltavica) 26 13 21 7 2 2 4 1 ------Complete shells 53 91 55 52 11 23 26 15 12 3 1 3 7 1 5 3 1 2 5 5 5 6 1 1 0 5 1 ------Total 13 18 10 1 1 1 1 1 2 2 5 ------Fragments 11 1 1 1 1 1 9 1 3 6 ------Est. Number of broken ind. Imparietula spp. 0 ------Complete shells 11 1 1 1 1 1 1 9 1 3 6 ------Total

------Fragments

------Est. Number of broken ind. Truncatellina 1 ------Complete shells cylindrica 1 ------Total

Fragments 2 2 1 8 ------

Est. Number of broken ind. 2 1 1 8 ------Vallonia pulchella 2 1 2 1 3 ------Complete shells 11 2 3 2 1 2 ------Total 7 2 1 ------Fragments 7 2 1 ------Est. Number of broken ind. Vitrea pygmaea 1 2 1 ------Complete shells 8 4 2 ------Total 33 14 10 1 ------Fragments 33 14 10 1 ------Est. Number of broken ind. Xeropicta derbentina 5 4 ------Complete shells 33 19 14 1 ------Total

------Fragments

------Est. Number of broken ind. Truncatellina 1 ------Complete shells costulata 1 ------Total 1 2 5 3 2 1 1 1 1 3 ------Fragments 1 2 5 3 2 1 1 1 1 3 ------Est. Number of broken ind. Multidentula pupoides

------Complete shells 1 2 5 3 2 1 1 1 1 3 ------Total 32 4 4 2 1 2 1 1 7 6 1 ------Fragments 23 4 3 2 1 2 1 1 7 6 1 ------Est. Number of broken ind. Vallonia costata 25 21 1 2 4 9 1 1 ------Complete shells 48 22 24 11 15 4 1 2 2 2 2 1 1 2 1 ------Total

------Fragments

------Est. Number of broken ind. Vertigo pygmaea 3 ------Complete shells 3 ------Total x x x x x x x x x x x ------Vertebrate teeth or bones x x x x ------Beetles x x ------Charcoal x ------Seeds

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Tab. 5.4 Palaeo-record of the gastropod species for the section BL. 81 80 79 78 77 76 75 74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 sample number 196 505 276 12 15 21 18 64 71 2 1 1 1 1 1 1 4 4 3 1 6 1 2 ------Fragments 151 479 248 11 17 18 59 71 2 1 1 1 9 1 1 1 4 2 2 1 5 1 1 ------Est. Number of broken ind. Ceciloides acicula 12 27 1 8 5 6 ------Complete shells 163 506 256 11 17 23 59 77 2 1 1 2 9 1 1 1 4 2 2 1 5 1 1 ------Total 17 18 11 10 11 20 11 10 26 29 7 8 5 8 2 4 1 5 3 1 1 1 1 2 1 1 3 5 1 3 7 5 6 2 4 8 2 6 4 1 1 7 ------Fragments 16 17 4 4 4 4 4 5 2 2 1 2 3 2 1 1 1 3 1 1 1 1 2 3 1 1 7 3 5 1 4 3 6 1 2 3 1 1 3 5 3 5 ------Est. Number of broken ind. Chondrula tridens 1 1 ------Complete shells 16 18 4 5 4 4 4 5 2 2 1 2 3 2 1 1 1 3 1 1 1 1 2 3 1 1 7 3 5 1 4 3 6 1 2 3 1 1 3 5 3 5 ------Total 46 1 1 1 ------Fragments 39 1 1 1 ------Est. Number of broken ind. Harmozica selecta 1 ------Complete shells 40 1 1 1 ------Total 335 141 10 32 10 10 23 10 15 54 12 60 66 42 30 16 3 2 2 2 5 1 1 2 4 5 5 8 4 7 3 1 2 5 5 2 4 6 1 1 1 7 4 2 3 4 1 3 7 4 4 1 4 3 2 2 2 1 1 2 1 3 4 3 2 8 2 1 9 ------Fragments 335 141 10 30 23 10 12 54 11 60 66 38 30 15 1 2 1 2 4 9 1 1 2 1 1 2 4 2 7 3 1 1 1 5 2 3 6 1 1 1 5 1 1 1 1 1 1 3 1 1 1 9 1 1 2 1 1 1 1 1 1 1 4 1 2 7 1 1 7 ------Est. Number of broken ind. Kalitinaia crenimargo 2 7 ------Complete shells 342 141 10 32 23 10 12 54 11 60 66 38 30 15 1 2 1 2 4 9 1 1 2 1 1 2 4 2 7 3 1 1 1 5 2 3 6 1 1 1 5 1 1 1 1 1 1 3 1 1 1 9 1 1 2 1 1 1 1 1 1 1 4 1 2 7 1 1 7 ------Total

------Fragments

------Est. Number of broken ind. Slugs 1 1 4 ------Complete shells 1 1 4 ------Total 694

------Fragments 694

------Est. Number of broken ind. Truncatellina sp. 61 ------Complete shells (*) ------Total

------Fragments

13 Gibbulinopsis interrupta 1 3 1 1 1 2 1 1 ------Complete shells 60 13 4 405 148 6 20 26 42 11 19 31 76 28 28 13 4 9 2 4 6 2 1 2 1 2 1 1 1 2 5 1 1 1 4 5 3 +2 1 2 5 +9 +33 6 ------Total +2 155 192 12 57 11 16 51 58 24 74 1 6 1 3 3 3 1 8 2 ------Fragments 151 192 12 57 11 14 51 58 24 74 1 5 1 2 3 3 1 5 2 ------Est. Number of broken ind. 1 8 2 3 4 5 ------Complete shells Pupilla poltavica 79 65 3 151 192

13 11 14 54 62 24 +162 Total 1 +11 5 1 2 3 3 +2 5 2 ------62 14 ------Fragments 62 14 ------Est. Number of broken ind. 11 1 ------Complete shells Pupilla kyrostriata 15 73

+30 Total ------550 433 404 1 2 5 5 2 ------Fragments 550 433 404 1 1 5 5 2 ------Est. Number of broken ind. 1 2 1 ------Complete shells Gibbulinopsis signata 434 7 1 550 404 Total +14 1 1 +1 5 +231 2 ------822 440 82 14 30 19 38 2 1 2 1 5 6 2 1 4 2 4 5 9 ------Fragments 822 320 82 14 30 19 38 2 1 2 1 1 6 2 1 4 2 4 5 9 ------Est. Number of broken ind. Pupilla sp. 1 ------Complete shells (*) (*) 2 1 2 1 1 6 2 1 1 2 ------Total 14 14 13 10 1 1 1 6 8 ------Fragments 1 1 1 6 4 5 8 4 5 ------Est. Number of broken ind. Imparietula. sp.

------Complete shells 1 1 1 6 4 5 8 4 5 ------Total 14 19 1 2 1 4 ------Fragments 14 15 1 2 1 4 ------Est. Number of broken ind.

152 Truncatellina 1 1 1 7 1 ------Complete shells cylindrica 156

21 15 Total 1 1 1 3 2 +435 ------290

90 87 Fragments 1 1 5 1 2 2 1 8 1 1 1 1 1 3 1 4 6 3 1 1 3 2 1 ------223

------Complete shells 12 37 21 2 ------Total 10 3 ------Fragments 8 3 ------Est. Number of broken ind. Truncatellina 40 ------Complete shells callicratis 43

+119 Total 8 ------116 126 14 59 15 40 45 88 11 2 4 4 2 4 3 1 3 1 2 1 3 4 8 1 2 3 1 4 1 1 1 3 ------Fragments 107 45 12 27 39 56 97 2 9 4 3 1 3 2 7 1 2 1 1 1 2 3 7 1 2 3 1 2 1 1 1 3 ------Est. Number of broken ind. Multidentula pupoides 1 ------Complete shells 107 45 12 27 39 56 97 2 9 4 3 1 3 2 7 1 2 2 1 1 2 3 7 1 2 3 1 2 1 1 1 3 ------Total 12 3 2 1 ------Fragments 10 2 2 1 ------Est. Number of broken ind. Vallonia costata 10 5 8 ------Complete shells 12 15 10 1 ------Total 1 ------Fragments 1 ------Est. Number of broken ind. Gastropod eggs 14 49 12 1 1 1 ------Complete shells 15 49 12 1 1 1 ------Total 328

------Fragments 264

------Est. Number of broken ind. Gibbulinopsis sp.

------Complete shells (*) ------Total 3 ------Fragments 3 ------Est. Number of broken ind. sp. Aegopinella

------Complete shells 3 ------Total x x x x x x x x x x x x x x x x x ------Vertebrate teeth or bones x ------Beetles x x x x x ------Seeds

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6 SUMMARY AND SYNTHESIS

6.1 COMPARATIVE CONSIDERATION OF THE DIFFERENT SETTINGS

In order to identify local differences and supra-regional similarities of factors influencing the geochemical and faunal composition of the Quaternary gastropod assemblages, we examined aeolianite-palaeosol archives of two highly sensitive and fundamentally different settings. Hereby we compared Fuerteventura, an oceanic island with a subtropical climate with a study area in the Lesser Caucasus foothills, nowadays characterised by a humid continental climate. For both study areas, we were able to investigate a period of at least three glacial-interglacial cycles, covering approximately the last 400 ka. Due to the long timespans disclosed and significant biostratigraphic patterns, the studied archives allowed us to generate a robust dataset, which is suitable for a multi-aspect consideration. In the following, I discuss the main aspects regarding similarities, differences and conclusions that were drawn from comparing both study areas. The response of gastropods to environmental conditions are analysed related to phases of geomorphodynamic stability vs. phases of sediment deposition regarding the following aspects:

 Geomorphodynamic stability versus sediment deposition in the context of temporal correlations The Southern Caucasian loess deposits alternate with pedocomplexes. Ecostratigraphic patterns related to these successions revealed that loess deposits were primarily associated with xerophilous gastropod species of shrub- and shortgrass steppes, while pedocomplexes and soil sediments are related to the presence of mesophilous gastropod species of highgrass- to forest steppes. Accordingly, loess-palaeosol successions of the Southern Caucasian study area seem to be related to climatic alterations, assumedly coinciding with glacial-interglacial cycles (also see Dodonov and Baiguzina, 1995, Joannin et al., 2010). However, since the chronological resolution of the archive formation processes is based on luminescence dating, and in view of the large uncertainties that are inherent to this method, a temporal correlation of our archives with global climate fluctuations seems problematic. This aspect, together with the complex system of interaction between the marine, terrestrial and atmospheric spheres makes it even more complicated to correlate our archives e.g. with marine isotope records (also see Bolikhovskaya and Molodkov, 2006, Zeeden et al., 2018). For the aeolianite-palaeosurface sequences on Fuerteventura, we equally found the most diverse ecosystems and the highest gastropod biodiversity in combination with palaeosurfaces, which in turn are related to phases of stability. In contrast to the Southern

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Caucasus area, we have a more complex sediment cycle on Fuerteventura, including sediment inputs from dust-bearing air layers of the Sahara, sands from exposed shelf positions and tephric fallout deposits (e.g., Meco & Pomel, 1985). Sediment accumulation on Fuerteventura is strongly influenced by volcanic lock-offs of sand fields and other local influences such as sediment availability, wind strength and wind directions (see Roettig et al., 2017). Since palaeosurfaces are therefore not necessarily climate-related, but exhibit a multi-causal history of origin, it is all the more difficult to assign the lithological units to glacial and interglacial as well as stadial and interstadial phases. Accordingly, it remains complicate by now to correlate the patterns and chronologies observed in both study areas.

 Humidity The investigated dune-sequences on Fuerteventura are characterised by sandy deposits that alternate with silty palaeosurfaces and tephric layers. As indicated by more negative δ13C results (see Chap. 4.5.1) and a higher gastropod biodiversity, we assume moister conditions for both types of palaeosurfaces. The finer silty substrates have a more favourable water retention capacity compared to sandy deposits that, in combination with the permanently available oceanic humidity (precipitated as dew and possibly sea-spray), probably raised the edaphic humidity. Therefore, we assume the substrate to be the most decisive factor for the establishment of ecosystems on Fuerteventura. We suggest that this effect is especially decisive in arid environments with increased air moisture but absence of direct rain events. Gastropod assemblages of the Southern Caucasian archives point to humidity alterations related to palaeosols and loess deposits, respectively. Pedocomplexes include mesophilous gastropod species, indicating moister climatic conditions (Chap 3.5), while unmodified loess layers are associated with exclusively xerophilous gastropod species, indicating dryer conditions. In contrast to oceanic settings, we assume precipitation to be the main source of moisture for the high-continental Lesser Caucasus foothills. As the air masses tend to be comparatively dry and as alternations in the substrate never underceed a critical water retention capacity (silt versus clay) we assume that the substrate would play a minor role for the South Caucasian deposits.

 Temperature For Fuerteventura, we assume that the temperature differences between glacial and interglacial respectively interstadial phases were strongly weakened due to the low latitude of the Canary Islands (Chap. 4.5.2). The investigated gastropod assemblages showed the strongest response to substrate changes, whereat this factor appeared to exceed the

166

effect of direct climate parameters (see Chap. 4.5.1 an d 4.5.2). Nevertheless, we assume that major faunal changes might have been forced by dry hot winds at the end of glacial phases, which were described by Moreno et al. (2001). However, for this scenario it remains unclear whether the main stress was caused by heat or drought stress. For the Caucasian archives, we may assume the classical approach of loess deposits being related to glacial phases (also see Meszner et al., 2011, Dodonov and Baiguzina, 1995, Joannin et al., 2010). Thus, our archives would point to lower temperatures related to loess deposition. However, we found that even during these colder phases, cold- adapted gastropod species were completely absent. Moreover, it is known from modern thermophilic species (such as Vallonia pulchella) of the study area that they ascend to higher altitudes, tolerating the alpine cold in favour of the increased humidity there. We therefore assume that despite the continental climate, temperatures were never too cold limiting gastropod species. We therefore suggest for the Southern Caucasian study sites, that the predominant limiting factor for gastropods and other biota was humidity rather than temperature (see Chap. 3.5.2).

 Pedogenesis In the Eastern Canary sediment archives, we do not see clear pedogenic characteristics in the sense of classic in-situ soil formation, but rather initial soil forming processes such as carbonate relocation or enrichment (Roettig et al., 2019). Nevertheless, we find soil- like ecosystems associated with palaeosurfaces that assumedly developed through the input of finer substrates, such as tephric material and Saharan dust. The input of these fine allochthonous substrates includes silt (mainly quartz), clay minerals (e.g. illit, kaolinit) and metal oxides (e.g. haematite) from the Sahara (Criado & Dorta, 2003, Suchodoletz et al., 2009).These components cause, among other things, a higher field capacity, cation- exchange capacity and nutrient supply, which in combination with morphodynamic stability, the establishment of vegetation and moisture availability presumably led to the formation of soil-like palaeosurfaces and, partially, subsequent in-situ pedogenesis. However, these palaeosurfaces are not genetically comparable with classical soils and probably formed in much shorter periods compared to the South Caucasian palaeosols. Also, for the South Caucasian palaeosols we have an input of fine dust and tephric material (allophanes) which probably accelerated soil formation, but we additionally have clear pedogenic indications of soil formation including de- and re-carbonatisation, mineral weathering, in-situ clay formation, etc. For the South Caucasian archives, we therefore assume, among other things, that soil formation was linked to sufficient rainfall, geomorphological stability and an exposure time of at least several thousand years. Despite differences in the genesis, pedomorphic stratigraphic units of both study areas

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are primarily characterised by a higher gastropod biodiversity compared to units without pedomorphic features.

 Biodiversity In the South Caucasian archives, the species richness of the gastropod assemblages is predominantly highest within pedocomplexes. Pedocomplexes were presumably related to highgrass- and forest steppes and a higher mean annual precipitation (Chap. 3.5.1). We assume that an increased species richness and equitability here were caused by the reduced drought stress and possibly a higher availability of niches (e.g. related to rotten trunks, shadowed habitats, leaf litter, etc.) compared to shortgrass- and shrub steppes. Nonetheless, also assemblages of pure loess units are partly characterised by a high biodiversity. We may need to differentiate between different degrees of aridity for dryer phases, as many xerophilous species that were found are adapted to rather moderate arid conditions. However, if the amount of precipitation falls below a certain limit, biodiversity also decreases. Moreover, we have to consider that the assemblages also overlap with preservation aspects. Accordingly, a quick imbedding and dryer environmental conditions can lead to a higher preservation rate of shells. On the other hand, despite a longer exposure-time which should promote the enrichment of gastropod remains, related shells can be dissolved during more intensive soil formation phases that are associated with decarbonatisation as an initial soil-forming process (see Ložek, 1990, Říhová et al., 2018). If we compare the Caucasian archives to Fuerteventura, we see two major differences: first, we seem to have major faunal changes/ extinction “events” that we assume to be related to the prevalence of strong winds during glacial terminations (see Moreno et al., 2001, Chap. 4.5.4) and that are different to long-term local glacial versus interglacial age conditions (Chap. 4.5.3). Second, long-term conditions of glacial versus interglacial phases do not seem to vary much, instead the gastropod communities rather react to changes in the substrate (Chap. 4.5.1). We assume that a finer substrate related to the input of Saharan dust or volcanic fallout deposits due to a higher water retention capacity significantly enhances the ground moisture conditions. Supposably, this effect especially relates to oceanic settings with high air moisture but very low annual precipitation amounts.

 Biozonation On Fuerteventura, there are clear faunal changes over the past 400 ka, which assumedly correspond to a regional pattern. Particular key species show abundance peaks in specific lithological units and partly disappear afterwards. Thus, the stratigraphy that can be compiled from gastropods on Fuerteventura is very close to a classical biostratigraphy in

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the geological sense, which is similarly based on key associations (Chap. 2.5.1). Compared to this, fluctuations in gastropod compositions of the South Caucasian study sites repeat over time, whereat certain assemblages indicate specific types of vegetation. We found that loess deposits are represented by semi-desert communities, while palaeosols are associated with highgrass- to forest-steppe biomes (Chap. 3.5.1). These significant faunal changes equally allow a biozonation, whereby biozones in this case are corresponding to ecozones. The extinction of various species did not take place until the Holocene, and is most likely related to the anthropogenic influence. However, as described in the beginning of this chapter, the correlation of our biozones with global climate shifts is not straightforward yet. Especially on Fuerteventura, there are many uncertainties with correlating palaeosurfaces with glacial-interglacial cycles, additionally as they are strongly influenced by volcanism and local sediment availability and surplus. These sedimentary cycles are not fully understood yet and a chronological correlation with the marine stable isotope stratigraphy seems complicate. However, our biostratigraphy may provide a solid stratigraphic fundament for now, independent from a definite chronological allocation.

The comparison of both study areas shows, that the effects of glacial-interglacial cycles on ecosystems depend strongly on site-specific characteristics and factors (e.g. continentality, latitude, prevailing winds, sediment availability, volcanism). The present study thus emphasizes the complexity of the influences that affect the quality of ecosystems, beyond exclusively climatic factors.

6.2 MAJOR CONCLUSIONS

This study presents an examination of Quaternary aeolianite-sequences covering the past 400 ka based on gastropod proxies. In order to differentiate between local and general patterns and to test the applicability of the method in different settings, we compared a highly continental archive in the Southern Caucasus to an oceanic setting on the Eastern Canary Islands. As the application of gastropods to terrestrial long-term climate records is rare yet, we were able to derive numerous new information from the analyses of our data. The most important findings are:

1) Palaeoecological information from the South Caucasian study area

We found that the Lesser Caucasus foothills were characterised by an alteration of loess deposits associated with dry conditions and a xerophilous shrub vegetation, and

169 pedocomplexes associated with moister conditions and mesophilous highgrass- to forest- steppes (Chap. 3.5.1). For colder phases of loess deposition we assume, that biota of the studied sites were limited by a drought-induced desert treeline ascending from the Kura lowlands instead of a cold-induced alpine treeline coming from above and that even during glacial periods, the average July temperatures were above 10°C (Chap. 3.5.2). We furthermore encountered a trend towards increasing aridisation for glacial periods over the last three glacial-interglacial cycles (Chap. 3.5.5).

2) Palaeoecological information from the eastern Canary study area

The Eastern Canary archives are composed of sandy deposits intercalated with palaeosurfaces. These palaeosurfaces were associated with more diverse gastropod communities and less xerophilous (C3) plant species compared to sandy layers. We furthermore assume that over the past 400 ka, ecosystems were only secondary influenced by fluctuations in local climate conditions as related to glacial versus interglacial phases. Instead, a strong influence was shown by changes in the substrate, assumedly influencing the edaphic moisture properties. These substrate changes were primarily related to the input and preservation of tephric material and Saharan dust, whereat a chronological correlation remains problematic, yet (Chap. 4.5.3). In addition, we observed prominent extinction events within the gastropod assemblages, which we assume were possibly caused by hot winds related to the end of glacial phases (Chap. 4.5.3, see Moreno et al., 2001).

3) Biostratigraphic application of Quaternary gastropods

It was possible to derive a robust stratigraphy based on gastropods in the different settings. The Caucasian loess deposits allowed an ecostratigraphic biozonation based on displacement and re-immigration of taxa of different ecological groups. In contrast, on the insular setting of the eastern Canary study area, it was even possible to develop a biostratigraphic zonation based on abundance peaks and extinction of certain taxa on the island, which is close to a biostratigraphic approach in the classical sense. In the latter case, the temporary occurrence of particular key species can be used for a first stratigraphic orientation in the field. Four of them, Pomatias lanzarotensis, Cochlicella sp., Rumina decollata and Obelus pumilio, if present with significant abundances, proved to be clearly attributable to specific lithological units and can be consistently found in the study area. The according key associations may allow using gastropod records to obtain a provisional stratigraphical and chronological classification of sediments on Fuerteventura.

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4) Stable isotopes of terrestrial Quaternary gastropods - New insights and limits

This work includes two of the first studies to investigate stable isotope signals of gastropod shells in geological archives with known stratigraphic context. The Southern Caucasian study region showed the difficulty to disentangle the various factors responsible for isotope fractionation, particularly in continental settings. However, the results of δ18O analyses of our gastropod shells indicate a strong influence by the δ18O signals of the ingested precipitation. These in turn seem to be predominated by the source region and the trajectory of the rain- bearing airmasses (Chap. 5.5.2). Contrarily, the oceanic position of the Canary Islands represents a special situation and assumedly allow us to use δ18O shell signals to reconstruct mean δ18O signals of the surface seawater and to correlate the deposits with sea level fluctuations (Chap. 4.5.3). Moreover, δ13C shell signals at the Canary study area enabled us to derive palaeo-vegetation. Merging both proxies, we were able to differentiate between edaphic moisture alternations forced by substrate changes and humidity alternations induced by climatic changes (Chap. 4.6). We therefore recommend, that stable isotope signals in gastropod shells have a high potential as palaeo-environmental indicators. However, the information derived from stable isotopes of terrestrial gastropod shells should not be generalised. Predominant site-specific factors should always be investigated and taken into account when interpreting the isotope signals.

5) Major factors influencing pedogenesis and ecosystems of the studied settings in the context of climate change

By comparing the conditions related to glacial vs. interglacial phases for both study areas, we tried to identify the predominant environmental factors influencing soil formation and the biodiversity and stability of ecosystems. For Fuerteventura, we assume that due to its low latitude position, glacial-interglacial cycles were not related to significant changes of mean annual temperatures and precipitation. Instead, changes in substrate associated with palaeosurfaces seem to have a strong influence on soil formation and ecosystems. These substrate-induced edaphic humidity increases (see Chap. 4.5.1) favoured biota and the establishment of soil-like ecosystems, while pedogenesis in the classical sense was just rudimentary due to the low annual rainfall amounts. Despite presumed hot winds at the end of glacial phases which would have significantly stressed the gastropod communities, we suggest that the most striking factor for the establishment of (soil) ecosystems was geomorphological stability and substrate input respectively. In contrast, the highly continental South Caucasian setting was strongly stressed by lower mean annual rainfall amounts during phases of loess deposition. Aridity seems to be the

171 dominant factor impeding pedogenesis, while higher rainfall amounts allowed soil formation, and moreover, led to the establishment of diverse ecosystems with mesophilous highgrass- and forest-steppes. Also in the Lesser Caucasian foothills, temperature was obviously not dominating the gastropod assemblages, as gastropod species associated with glacial periods did not include cryophilous elements and indicate that average July temperatures did not fall below 10°C. Based on our results for several glacial- interglacial cycles of both studied settings, we suggest that the most important factor for biota and soil-ecosystems was aridity stress. For the Canary study sites, the absence of precipitation could partly have been compensated by a significant enhancement of the substrate properties by means of an increased water retention capacity. Accordingly, we suggest that the actual aridity stress can best be assessed by retracing the available edaphic humidity, rather than taking exclusively climatic parameters into account.

6.3 PERSPECTIVE

The application of gastropod analyses to Quaternary sediment archives proved to be a valuable environmental and climatic proxy. Accordingly, it would be worthwhile:

(1) to apply the malacological approach to further geological archives in order to obtain more information on terrestrial ecosystems and to reveal interregional patterns. For example, a transect across the Lesser Caucasus could show to which altitudes cold- adapted gastropod species were absent in order to characterise environments related to glacial periods. Such a transect could also indicate whether forests/ forest steppes have ascended to higher regions during phases of loess deposition or if they were completely displaced by the confluence of desert- and alpine treelines, which would explain the species poverty of forest snails at the studied sites. (2) We should furthermore extent the research area e.g., to loess archives north of the Black Sea or northern tongues of the Russian loess belt which are not that strongly influenced by surrounding mountain areas. These could reveal if the aridisation trend observed for glacial periods of the last 400 ka is based on local (orogenic?) phenomena or represent a supra-regional pattern. In addition, the field studies showed that there are further loess-palaeosol sequences in the Lesser Caucasus foothills that disclose a period of presumably up to one million years (Maghavus section), which could help to retrace the observed aridisation trend over an even longer period. (3) Additionally, it would be promising to excavate further sequences at the Canary Islands, e.g. on Lanzarote and to see if the geographical range of stratigraphic key species can be extended to further islands of the Canary archipelago. Additionally, a comparison of

172 fossil gastropods on other islands embedded in a chronostratigraphic context could enable us to disclose new insights into the evolutionary and biogeographic history of certain taxa. (4) We should better investigate major influences on stable isotopes of specific gastropod taxa. The isotopic composition of gastropod shells proved to be a potent proxy for palaeo-environmental conditions. However, we suggest carrying out further studies on modern Kalitinaia crenimargo and related taxa to compare the shell isotope signals with the isotopic composition of modern precipitation and climate data. This would promote a better understanding of the specific dependencies of stable isotope signals on certain environmental factors and thus a more reliable interpretation of the isotopic signals of fossil gastropod shells. (5) It would also be useful to try to put our findings into practice. This study shows that especially in desert settings, substrate can play a key role for the quality of ecosystems. Especially on Fuerteventura, it becomes apparent that there is a massive degradation of the surface substrate through pasture and anthropogenic use. This leads to erosion of soil-like ecosystems and the extinction of species, which are especially irreversible due to their high number of endemic taxa. Protection areas and an adapted (sustainable) land use could help to stop this process.

6.4 REFERENCES

Bolikhovskaya, N. S. & A. N. Molodkov (2006). East European loess-palaeosol sequences: palynology, stratigraphy and correlation. Quaternary International, 149, 24–36.

Criado, C. & P. Dorta (2003). An unusual blood rain on the CanaryIslands: the storm of January 1999. Journal Arid Environments, 55, 765–783.

Dodonov, A. E. & L. L. Baiguzina (1995). Loess stratigraphy of Central Asia: palaeoclimatic and palaeoenvironmental aspects. Quaternary Science Reviews 14, 707–720.

Joannin, S., Cornée, J. J., Münch, P., Fornari, M., Vasiliev, I., Krijgsman, W., Nahapetyang, S., Gabrielyanh, I., Ollivier, V., Roironk, P. & C. Chataigner (2010). Early Pleistocene climate cycles in continental deposits of the Lesser Caucasus of Armenia inferred from palynology, magnetostratigraphy, and 40Ar/39Ar dating. Earth and Planetary Science Letters, 291(1-4), 149-158.

Ložek V. (1990). Molluscs in loess, their paleoecological significance and role in geochronology ‐ Principles and methods. Quaternary lnternational, 7, 71–79.

Meco J. & R. Pomel (1985). Les formations marines et continentales intervolcaniques des

173 Iles Canaries orientales (Grande Canarie, Fuerteventura et Lanzarote): Stratigraphie et signification paléoclimatique. Estudios geológicos, 41, 223–227.

Moreno, A., Targarona, J., Henderiks, J., Canals, M., Freudenthal, T. & H. Meggers (2001). Orbital forcing of dust supply to the North Canary Basin over the last 250 kyr. Quaternary Science Reviews, 20(12), 1327-1339.

Říhová, D., Janovský, Z., Horsák, M. & L. Juřičková (2018). Shell decomposition rates in relation to shell size and habitat conditions in contrasting types of Central European forests. Journal of Molluscan Studies, 84(1), 54-61.

Roettig, C. B., Varga, G., Sauer, D., Kolb, T., Wolf, D., Makowski, V., Espejo, J. M. R., Zöller, L. & D. Faust (2019). Characteristics, nature, and formation of palaeosurfaces within dunes on Fuerteventura. Quaternary Research, 91(1), 4-23.

Suchodoletz, H., Kühn, P., Hambach, U., Dietze, M., Zöller, L. & D. Faust (2009). Loess-like and palaeosol sediments from Lanzarote (Canary Islands/Spain)-indicators of palaeoenvironmental change during the Late Quaternary. Palaeogeography, Palaeoclimatology, Palaeoecology, 278(1-4), 71-87.

Zeeden, C., Hambach, U., Obreht, I., Hao, Q., Abels, H. A., Veres, D., Lehmkuhl, F., Gavrilov, M. B. & S. B. Marković (2018). Patterns and timing of loess-paleosol transitions in Eurasia: Constraints for paleoclimate studies. Global and Planetary Change, 162, 1-7.

174 Übereinstimmungserklärung:

Die Übereinstimmung dieses Exemplars mit dem Original der Dissertation zum Thema:

„ Investigations on Quaternary environmental changes based on malacological analyses and stable isotope signals “ wird hiermit bestätigt.

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175 Erklärung zur Eröffnung des Promotionsverfahrens

1. Hiermit versichere ich, dass ich die vorliegende Arbeit ohne unzulässige Hilfe Dritter und ohne Benutzung anderer als der angegebenen Hilfsmittel angefertigt habe, die aus fremden Quellen direkt oder indirekt übernommenen Gedanken sind als solche kenntlich gemacht.

2. Bei der Auswahl und Auswertung des Materials sowie bei der Herstellung des Manuskripts habe ich Unterstützungsleistungen von den Personen erhalten, die als Co-Autoren der Aufsätze erwähnt sind. Als Erstautor aller Aufsätze bin ich verantwortlich für die Struktur der Dokumente und die Anfertigung der Abbildungen und Tabellen. Ich bin ebenso verantwortlich für die Kommunikation während der Einreichung, Begutachtung, Revisionen und Veröffentlichung der Aufsätze. Die unten aufgeführten Arbeiten wurden von folgenden Personen durchgeführt:

- Messungen der stabilen Isotopensignale mittels Massenspektraler Verfahren wurden durch Dr. Stefania Milano (MPI Leipzig) und Prof. Michael Joachimski (Geozentrum Nordbayern) durchgeführt

3. Weitere Personen waren an der geistigen Herstellung der vorliegenden Arbeit nicht beteiligt. Insbesondere habe ich nicht die Hilfe eines kommerziellen Promotionsberaters in Anspruch genommen. Dritte haben von mir weder unmittelbar noch mittelbar geldwerte Leistungen für Arbeiten erhalten, die im Zusammenhang mit dem Inhalt der vorgelegten Dissertation stehen.

4. Die Arbeit wurde bisher weder im Inland noch im Ausland in gleicher oder ähnlicher Form einer anderen Prüfungsbehörde vorgelegt und ist – sofern es sich nicht um eine kumulative Dissertation handelt – auch noch nicht veröffentlicht worden.

5. Sofern es sich um eine kumulative Dissertation gemäß § 10 Abs. 2 handelt, versichere ich die Einhaltung der dort genannten Bedingungen.

6. Ich bestätige, dass ich die Promotionsordnung der Fakultät Umweltwissenschaften der Technischen Universität Dresden anerkenne.

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