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Heinrich Event 4 Characterized by Terrestrial Proxies in Southwestern Europe

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Heinrich Event 4 Characterized by Terrestrial Proxies in Southwestern Europe EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Natural Hazards Natural Hazards and Earth System and Earth System Sciences Sciences Discussions Open Access Open Access Atmospheric Atmospheric Chemistry Chemistry and Physics and Physics Discussions Open Access Open Access Atmospheric Atmospheric Measurement Measurement Techniques Techniques Discussions Open Access Open Access Biogeosciences Biogeosciences Discussions Open Access Open Access Clim. Past, 9, 1053–1064, 2013 Climate www.clim-past.net/9/1053/2013/ Climate doi:10.5194/cp-9-1053-2013 of the Past of the Past © Author(s) 2013. CC Attribution 3.0 License. Discussions Open Access Open Access Earth System Earth System Dynamics Dynamics Discussions Heinrich event 4 characterized by terrestrial proxies in Open Access Open Access southwestern Europe Geoscientific Geoscientific Instrumentation Instrumentation J. M. Lopez-Garc´ ´ıa1, H.-A. Blain2,3, M. Bennasar` 2,3, M. Sanz4, and J. Daura4 Methods and Methods and 1Gruppo di Ricerca di Paleobiologia e Preistoria. Dipartamento di Studi Umanistici, Data Systems Data Systems Universita` degli Studi di Ferrara. C.so Ercole 1 d’Este 32, 44121 Ferrara, Italy Discussions Open Access 2IPHES, Institut Catala` de Paleoecologia Humana i Evolucio´ Social, C/Escorxador s/n, 43003 Tarragona, Spain Open Access 3 Geoscientific Area` de Prehistoria,` Universitat Rovira i Virgili (URV), Avinguda de Catalunya 35, 43002Geoscientific Tarragona, Spain 4Grup de Recerca del Quaternari, SERP, Dept. Prehistoria,` H. Antiga i Arqueologia, Universitat de Barcelona, C/Montalegre, Model Development Model Development 6, 08001 Barcelona, Spain Discussions Correspondence to: J. M. Lopez-Garc´ ´ıa ([email protected]) Open Access Open Access Received: 13 December 2012 – Published in Clim. Past Discuss.: 4 February 2013 Hydrology and Hydrology and Revised: 15 April 2013 – Accepted: 15 April 2013 – Published: 7 May 2013 Earth System Earth System Sciences Sciences Abstract. Heinrich event 4 (H4) is well documented in the 1 Introduction Discussions Open Access North Atlantic Ocean as a cooling event that occurred be- Open Access tween 39 and 40 Ka. Deep-sea cores around the Iberian Peninsula coastline have been analysed to characterize the The Heinrich events have been generally defined, accord- Ocean Science Ocean Science 18 H4 event, but there are no data on the terrestrial response ing to Cayre et al. (1999), by a decrease in δ O, peaks in Discussions to this event. Here we present for the first time an analy- magnetic susceptibility, an increase in the proportion of the sis of terrestrial proxies for characterizing the H4 event, us- foraminifer Neogloboquadrina pachyderma, as well as the Open Access ing the small-vertebrate assemblage (comprising small mam- appearance of IRD (iceberg rafted detritus). OfOpen Access these events, Heinrich event 4 (H4), which occurred ca. 39–40 Ka, is one mals, squamates and amphibians) from Terrassa Riera dels Solid Earth Canyars, an archaeo-palaeontological deposit located on the of the most abrupt climate coolingSolid episodes, Earth well recorded seaboard of the northeastern Iberian Peninsula. This assem- in sediment cores throughout the North Atlantic Ocean and Discussions blage shows that the H4 event is characterized in northeastern the adjacent continents (Roche et al., 2004; Sepulchre et al., Iberia by harsher and drier terrestrial conditions than today. 2007). Deep-sea cores around the Iberian Peninsula coastline Our results were compared with other proxies such as pollen, have been analysed to characterize the HeinrichOpen Access event fluctu- Open Access charcoal, phytolith, avifauna and large-mammal data avail- ations (Cacho et al., 1999; Sanchez-Go´ ni˜ et al., 2002; Sierro The Cryosphere able for this site, as well as with the general H4 event fluc- et al., 2005; NaughtonThe et al., Cryosphere 2009, among others). Taking Discussions tuations and with other sites where H4 and the previous and into account the recent data provided by these deep-sea core subsequent Heinrich events (H5 and H3) have been detected analyses, the H4 event can be characterized at the Iberian in the Mediterranean and Atlantic regions of the Iberian margins, according to Naughton et al. (2009), by two main Peninsula. We conclude that the terrestrial proxies follow the phases: (1) a first phase marked by relatively wet and very same patterns as the climatic and environmental conditions cold atmospheric conditions; and (2) a second phase marked detected by the deep-sea cores at the Iberian margins. by an extreme continental dryness and cooler conditions. Ac- cording to Sanchez-Go´ ni˜ et al. (2002), moreover, there are differences between the data obtained by the deep-sea cores for the H4 event at the Mediterranean and the Atlantic mar- gins of the Iberian Peninsula, the H4 event being more hu- mid at the Atlantic than the Mediterranean margin. Further- more, simulation models and pollen extrapolations from the deep-sea cores have been undertaken in order to observe the Published by Copernicus Publications on behalf of the European Geosciences Union. 1054 J. M. Lopez-Garc´ ´ıa et al.: Heinrich event 4 characterized by terrestrial proxies in southwestern Europe Fig. 2. Plot of the Canyars 14C dates, calibrated with the Intcal09 curve (Reimer et al., 2009) and compared with the North Green- Fig. 1. Location of the sites mentioned in text in the Iberian Penin- land Ice Core Project (NGRIP) δ18O ice-core record of Svensson sula, including Canyars (Terrasses de la Riera dels Canyars). et al. (2006) and Andersen et al. (2005), showing GI interestadials and Heinrich Event 4 according to Svensson et al. (2008) (prepared using OxCal vs. 4.1.7; Bronk Ramsey, 2009). terrestrial response to the H4 event in the Iberian Peninsula (Sanchez-Go´ ni˜ et al., 2002; Sepulchre et al., 2007; Naughton et al., 2009; Fletcher and Sanchez-Goni,˜ 2008; Fletcher et logical collection from an emplacement that is not known al., 2010; Bout-Roumazille et al., 2007; Combourieu Nebout precisely (Villalta, 1953); another corresponds to an iso- et al., 2002, among many others). Here we present for the lated proboscidean remains (cf. Mammuthus) from a differ- first time a characterization of the environment and climate ent gravel-pit 700 m from Canyars (Daura and Sanz, 2009). of the H4 event based on the small-vertebrate assemblage Other palaeontological remains from adjacent valleys have of the Terrasses de la Riera dels Canyars (henceforth, Can- been recovered in the course of archaeological survey exca- yars). Our results are compared with the pollen, charcoal, vations; Riera de Sant Llorenc¸has provided large-mammal phytolith, avifauna and large-mammal data obtained for this remains, mainly Mammuthus, Coelodonta and Equus (Daura site (Daura et al., 2013), as well as with the general H4 event et al., 2013). fluctuations to see whether the phases detected by Naughton Canyars is located at the confluence of two creeks, Ri- et al. (2009) can be observed for the Canyars data. They are era dels Canyars and Riera de Can Llong. The former is also compared with data from other sites where H4 and the the main stream, and its distal part probably consisted of a previous and subsequent Heinrich events (H5 and H3) have floodplain crossed by channels, nowadays modified by farm- been detected in the Mediterranean and Atlantic regions of ing activity (Daura et al., 2013). A total of 9 lithological the Iberian Peninsula, to observe whether or not the terres- units have been described, consisting of a poorly sorted and trial proxies follow the same patterns as the climatic and en- coarse-grained complex of gradational and incised fluvial de- vironmental conditions detected by the deep-sea cores at the posits. Palaeontological remains come from the only archae- Iberian margins. ological unit (MLU, Middle Lutitic Unit), consisting of mud- supported gravel filling a well-defined palaeochannel (LDU, Lower Detritical Unit). 2 Site description and chronology Several charcoal samples were collected for radiocar- bon dating, with a 14C dating result of ∼ 34.6 14C(∼ 39.6 Canyars is a fluvial deposit located in the town of Gava,` some cal.) Ka (overall mean age estimate from four radiocarbon 20 km to the west of Barcelona, in Vall de la Sentiu, one of datings by Daura et al., 2013) (Table 1; Fig. 2). the creeks originating at the foot of the Garraf Massif that flows into the beaches of the Mediterranean seaboard. The site was discovered in 2005 (Daura and Sanz, 2009; Daura et 3 Material and methods al., 2013) by an amateur archaeologist (C. Valls) and com- pletely excavated by the Grup de Recerca del Quaternari 3.1 Small-vertebrate sorting and palaeontological study from June to November 2007. Nowadays, Canyars is located in an abandoned gravel- The small-vertebrate fossil remains used for this study con- pit that remained active until the 1960s. Pleistocene fossils sist mainly of disarticulated bone fragments and isolated from the same area were already known. The first discovery teeth collected by dry and water screening. All the sedi- from Vall de la Sentiu was an Upper Pleistocene palaeonto- ment was dry-screened using superimposed 5 and 0.5 mm Clim. Past, 9, 1053–1064, 2013 www.clim-past.net/9/1053/2013/ J. M. Lopez-Garc´ ´ıa et al.: Heinrich event 4 characterized by terrestrial proxies in southwestern Europe 1055 Table 1. Radiocarbon dates from Canyars. Ages (BP, before present) are calibrated with the OxCal 4.1.7 software (Bronk Ramsey, 1995) using the IntCal09 curve (Reimer et al., 2009). Page 1/1 Site Inventory Material Lab# Pre-treatment δ13C AgeBP calBP(2 ) − ± Copernicus Publications Contact Legal Body Bahnhofsallee 1e [email protected] Copernicus Gesellschaft mbH TC07-I-L24-MCV Charcoal Beta273965 ABA 23.5 ‰ 33 800 350 37 405–3937081720 Göttingen http://publications.copernicus.org Based in Göttingen Germany Phone +49-551-900339-50 Registered in HRB 131 298 Fax +49-551-900339-70 County Court Göttingen Martin Rasmussen (Managing Director) Tax Office FA Göttingen Nadine Deisel (Head of Production/Promotion) USt-IdNr.
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