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LSU Historical Dissertations and Theses Graduate School
1997 Biostratigraphic and Paleoenvironmental Significance of Jurassic Microfossils From Romania. Andrei Tudoran Louisiana State University and Agricultural & Mechanical College
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Recommended Citation Tudoran, Andrei, "Biostratigraphic and Paleoenvironmental Significance of Jurassic Microfossils From Romania." (1997). LSU Historical Dissertations and Theses. 6530. https://digitalcommons.lsu.edu/gradschool_disstheses/6530
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. BIOSTRATIGRAPHIC AND PALEOENVIRONMENTAL SIGNfflCANCE OF JURASSIC MICROFOSSILS FROM ROMANIA
A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Geology and Geophysics
by Andrei Tudoran M.S., University of Bucharest, 1987 August 1997
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Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGMENTS I would like to thank my supervisor Dr. Joseph E. Hazel for providing necessary
insights, support and encouragement throughout this investigation.
This study has been made possible by the financial support of Amoco Production
Company. In this respect, special thanks go to Ms. Trary Ikltonic (Houston) and Dr. John Huckerby (New Plymouth) for their interest and support of this
investigation. I would also want to thank Dr. Heinz Malz (Frankfurt), Dr. Allan Lord (London), Dr. Ian Boomer Qforwich), Dr. Christiane Ruget (Lyon) and Dr. Joachim Blau (Giessen) for reviewing the ostracod and foraminifer identifications of the Lower and Middle Jurassic, as well as for their interest and cooperation. I gratefully acknowledge the help of Dr. Ovidiu Dragastan (Bucharest), who made available to me samples from the Popa-Patrulius-Dragastan collection, and for his most useful advice concerning the Upper Jurassic microfossils and bibliographic references. I also warmly thank Dr. Theodor Neagu (Bucharest) for the advice concerning the collection of outcrop material and review of identifications and Dr. Aurelia Barbulescu (Bucharest) for providing the material from Piatra Tasaul section. I am grateful to Dr. Paul Sikora (Houston) for his advice concerning the quantitative analysis of the data. Dr. Megan Jones (Baton Rouge) is thanked for introducing me to the JMP software; warm thanks also go to Dr. Xiaogong Xie (Baton Rouge) for his help in
capturing SEM images and to Mr. Rick Young for his assistance with thin sections.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ACKNOWLEDGMENTS...... ü LIST OF TABLES...... v LIST OF FIGURES...... vi ABSTRACT...... ix CHAPTER 1 INTRODUCnON ...... I Objectives...... I Plate tectonic setting ...... I Geologic setting ...... 4 E*revious studies ...... 9 2 MATERIALS AND METHODS...... 12 Material and sample preparation ...... 12 Microfaunal parameters ...... 12 Quantitative analysis ...... 13 3 SINEMURIAN - PLŒNSBACHIAN (LOWER JURASSIC) FORAMINIFERA AND OSTRACODS FROM ROMANIA...... 16 Lithology ...... 16 Biostratigraphy...... 17 Paleoenvironments ...... 19 Paleobiogeography ...... 24 4 TOARCIAN (LOWER JURASSIC ) FORAMINIFERA AND OSTRACODS FROM BRATCA, NORTHERN APUSENI MOUNTAINS. ROMANIA...... 27 Biostratigraphy...... 27 Taphonomic observations ...... 34 Paleoenvironments and sea-Ievel variations 36 Paleobathymetric model for microfauna distribution ...... 48 Paleobiogeography ...... 53 Systematics...... 54
5 BAJOCIAN (MIDDLE JURASSIC) FORAMINIFERA AND OSTRACODS FROM STRUNGULTTA, EASTERN CARPATHIANS, ROMANIA...... 70 L ith o lo ^ ...... 70 Biostratigraphy...... 72 Paleoenvironments ...... 73 Paleobiogeography ...... 77 Systematics...... 78 6 B ATHONIAN - CALLOVIAN (MIDDLE JURASSIC) FORAMINIFERA AND OSTRACODS FROM ROMANIA...... 82 Lithology and biostratigraphy ...... 82
III
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Taphonomic observations ...... 83 Paleoenvironments ...... 87 Eustatic co n tex t ...... 89 Paleobiogeography ...... 91 Systematics...... 92 7 OXFORDIAN-KIMMERIDGIAN (UPPER JURASSIC) FORAMINIFERA AND OSTRACODS FROM THE PREDOBROGEAN DEPRESSION (SCYTHIAN PLATFORM, ROMANIA)...... 96 Geologic setting and lithology ...... 96 Biostratigraphy...... 97 Paleoenvironments and sea-level variations 103 Paleobathymetric m o d el ...... 107 Paleobiogeography ...... 109 Systematics...... I ll 8 CONCLUSIONS. JURASSIC EVOLUTION OFTHE CENTRAL TETHYS: MICROFAUNAL EVIDENCE .... 124 Evolutionary events and biostratigraphy ...... 124 Lower Jurassic ...... 124 Middle Jurassic ...... 127 Upper Jurassic...... 128 Paleogeography ...... 130 Lower Jurassic ...... 130 Middle Jurassic ...... 136 Upper Jurassic ...... 138 Paleoenvironments and sea-level variations 141 Paleobathymetric m odels ...... 146
REFERENCES ...... 150 APPENDIXES A TA B LES...... 161 B MICROFOSSIL L IS T S ...... 165 C MICROFOSSIL PLATES ...... 178 VITA ...... 211
IV
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES 1.1 Important references grouped by to p ic ...... 162
1.2 Foraminifer data from Bratca section ...... 163
1.3 Ostracod data from Bratca section ...... 164
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES
1.1 Generalized tectonic map of southeastern Europe, showing the possible locations of the main Tethyan suture (after Picha, 1996) ...... 2
1.2 Plate tectonic reconstruction for the Late Jurassic (after Scotese, 1991 ) ...... 6
1.3 Generalized tectonic map of Romania, showing the locations of the investigated sections and w e lls ...... 7
1.4 Subdivisions of the Jurassic p e rio d ...... 8 2.1 Stratigraphie intervals covered by the investigated sections and wells ...... 15 3.1 Lithology and stratigraphy of ±e Munteana, Lacu Rosu, Moneasa, Garda Seaca, and Piatra Bulzului sections ...... 21 3.2 Range charts for the microfossil species identified in the Munteana, Lacu Rosu, Moneasa, Garda Seaca, and Piatra Bulzului sections 22 4.1 Lithology and microfaunal parameters of Bratca section ...... 31 4.2 Comparative range charts for selected foraminifer and ostracod species firom Bratca section ...... 32 4.3 Bratca section biozonation compared to other microfauna-based zonal schemes ...... 33 4.4 Q-mode cluster analysis of the samples from Bratca section, using the Euclidian distance to identify biofacies u n its ...... 43
4.5 Biofacies units and subunits in Bratca section, based both on Q-mode cluster analysis and geologic interpretation of the sam ples ...... 44 4.6 Q-mode cluster analysis of the samples from Bratca section, using as parameters foraminifer diversity, heterogeneity and percentages of fragmented specimens in order to identity biofacies subunits 45
4.7 Tridimensional plot of samples from the Bratca section as a function of foraminifer diversity, heterogeneity, and percentage of fragmented specimens ...... 46 4.8 Comparison of the relative sea-level curve for the Bratca section with Toarcian eustatic sea-level curves of other authors ...... 47
4.9 R-mode cluster analysis of foraminifer species from Bratca section, using the Euclidian distance and averages of the relative abundance of the species in the samples of each biofacies subunit...... 50 4.10 Paleobathymetric distribution for selected foraminifer species from Bratca section. Shaded areas reflect averages of relative abundance per biofacial
VI
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. subunit from fig. 11. (*) indicates species whose total number of specimens is <100 (L. pennensis - 44; L. obonenis - 1 9 ...... 51 5.1 Lithology and macrofauna of the Strungulita section ...... 71
5.2 Microfauna distribution and parameters in the Strungulita section.. 75 6.1 Lithostratigraphic column of section B ig a r ...... 84
6.2 Lithostratigraphic column of section Piatra T asau l ...... 85 6.3 Lithostratigraphic column of well Vinderei IP S o u th ...... 86 7.1 Lithostratigraphy of the deposits from wells Caraorman West FI 1/7 and Crasnicol F61808 ...... 100 7.2 Ranges of selected foraminifer and ostracod species from the Caraorman West FI 1/7 and Crasnicol 61808 w e lls...... 101 7.3 Lithology and microfaunal parameters of the Upper Jurassic deposits from well Caraorman West FI 1 /7 ...... 102 7.4 Biozonation of Jurassic deposits from wells Crasnicol F61808 and Caraorman West FI 1/7, compared to existing microfauna-based zonations ...... 113 7.5 Q-mode cluster analysis of samples from the Caraorman West FI 1/7 and Crasnicol F61808 wells, used to identify biofacies u n its ...... 114 7.6 R-mode cluster analysis of selected foraminifer species and groups from the Caraorman West FI 1/7 and Crasnicol F61808 wells and their average relative abundance in each biofacies ...... 115 7.7 Paleobathymetric distribution of selected foraminifer species from the Upper Jurassic of the Caraorman West FI 1/7 and Crasnicol F61808 wells. Shaded areas reflect average relative frequency per biofacies from fig. 7 . 6 ...... 116 7.8 Paleobathymetric distribution of selected foraminifer and ostracod species in the Oxfordian-Kimmeridgian of the Predobrogean Depression .. 117 8.1 Distribution of Jurassic foraminifer assemblage Qrpes as a function of paleobathymetry and paleolatitude, with the plots of the assemblages identified by the present study (after Basov, 1991) ...... 133 8.2 Distribution of large benthic foraminifera in the Tethys area during the Pliensbachian (after Bassoullet et al., 1985)...... 134 8.3 Distribution of total organic carbon in the Tethys area during the Toarcian (from Baudin et al., 1985)...... 140 8.4 Environments identified in the investigated sections ...... 144
Vll
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8.5 Sea-level variations in the investigated sections, compared to eustatic sea-level curves of different a u th o rs ...... 145
8.6 Paleobathymetric distribution model for Toarcian microfauna from the Apuseni M ountains ...... 148
vni
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Foraminifera and ostracods from eight measured sections and three wells located
in Romania (Apuseni Mountains, central Carpathian and foreland units) were analyzed. Major Jurassic microfaunal evolutionary events are recorded and
biozonations of regional value, based on assemblage zones, are established for the
Toarcian of the Apuseni Mountains and the Oxfordian-Kimmeridgian of the Scythian Platform. Microfauna has been calibrated to ammonite zones in the Bratca and Munteana sections, and the Caraorman West FI 1/7 well. Criteria such as 1) presence/absence of large benthic foraminifera with complex internal structure, 2) palecbiogecgraphic affinities of smaller foraminifera and ostracods, and 3) distribution of important lithofacies indicate a north Tethyan location for the central Carpathian and foreland units during the Sinemurian-Oxfordian interval. A similar location is assigned during the Lias to the Apuseni Mountains, with evidence for a somewhat more southern position with respect to the central Carpathian units. Paleobiogeographic evidence for a southern drift of the Tlsia plate begins to appear during the Oxfordian, supporting the hypothesis that the main Tethyan suture is located between the Apuseni Mountains and the Eastern and Southern Carpathians. Microfaunal evidence also indicates that if during the Triassic the Tisia plate was located on the southern margin of the Paleo-Tethys, this ocean must have closed by Early Jurassic.
Depositional environments ranging from inner to outer neritic are identified based on sedimentologic data and microfaunal parameters (diversity, heterogeneity, abundance, percentage of foraminifera fragmentation, rate of faunal change). A sequence stratigraphie ffameworJc is established for most sections; inferred relative
sea-level variation curves are generally similar to eustatic curves proposed by other authors. Important dysaerobic intervals were identified in the early Toarcian of the Apuseni Mountains and the late Bathonian of the Scythian Platform. Major sea-level
IX
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. rises are recognized during the late Sinemurian, early Toarcian, late Bajocian, late
Bathonian, and middle Oxfordian. Models for the paleobathymetric distribution of
main microfaunal species are established for the Toarcian and Oxfordian-
Kimmeridgian using quantitative analysis to identify biofacies and interpreting the latter according to the identified environments.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1. INTRODUCTION
Objectives The purpose of this study is to analyze the microfaunal content (foraminifera and ostracods) from the Jurassic deposits of eleven sections and wells located in Romania
and to interpret the results, as well as a comprehensive review of the existing
literature, in order to solve geologic problems in the following areas: - biostratigraphy: to identify the major evolutionary events, to establish biozonations where appropriate, and to calibrate the microfauna to ammonite zones
whenever possible. - paleoenvironments: to reconstruct paleoenvironments based on
sedimentologic data and microfaunal parameters. - sequence stratigraphy: to identify sea-level variations based on paleoenvironmental trends and to compare them with proposed eustatic sea-level curves, to recognize sea-level cycles and systems tracts. - paleobiogeography: to identify the paleobiogeographic afïïnities of the investigated tectonic units, especially in respect to the closing of the Paleo-Tethys
ocean and the opening of the North Apulian seaway. - paleobathymetry: to establish models for the paleobathymetric distribution of the principal microfaunal species.
Plate tectonic setting The Carpathian Arch is part of the Alpine-Himalayan folded belt, generated by the collision of the Eurasian plate and the African and hidian plates, as the Tethys Ocean closed during the Late Mesozoic and Cenozoic (Dercourt er of., 1986,1993). In
southeastern Europe, an area generally corresponding to the Jurassic Central Tethys (fig. 1.1), the complexity of this collision area is increased by the presence, between the European and the African plates, of a number of smaller continental fragments.
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C/) (/) Fig. 1.1 Generalized tectonic map of southeastern Europe, showing the possible locations of the main Tethyan suture (after Picha, 1996). I j The Apulian Block (fig. 1.2), including the area of present day Italy, the Adriatic Sea
and Croatia, represents the most important such continental fragment. During the
Jurassic, the Apulian Block was a part of the African Plate (Dercourt et al., 1993), but
the paleotectonic evolution of the smaller microplates of the Jurassic Central Tethys is still poorly known. One of these continental fragments is the Transylvan-Pannonian
or the Tisia plate, which corresponds to the Pannonian and Transylvanian
Depressions, and the Northern Apuseni Mountains, which separate ±em. One of the most intriguing problems of southeastern European geology is the exact location of the main Tethyan suture in this area (fig. 1.1). This suture, separating “European” fragments from “African” ones, can be easily followed from northwestern Turkey, between the Taurid and Pontid units, to the Vardar ophiolite zone, separating the Dinarid Mountains from the Balkan Mountains (Burchfiel, 1980). The suture is also readily identifiable in the Alps and in the western Mediterranean between Sardinia and the Tyrrhenian Sea (Burchfiel, 1980), but its position in respect to the Tisia plate is still debated. Existing interpretations range from a straight connection between the Vardar zone and the Alps (Ziegler, 1988) to a location that follows the ophiolitic complexes of the Southern Apuseni and the Pieniny Klippen Belt of the Western Carpathians (Dercourt et al., 1986, 1993). A consensus seems to have been reached conceming the opening during the Middle Jurassic of a North Apulian seaway, connected to the west with the opening Central Atlantic. This
seaway was completely destroyed by the end of the Jurassic, when Apulia collided with Eurasia due to the opening of an South Apulian seaway (Mesogea), resulting in the main Tethyan suture (Dercourt et at., 1986, 1993; Ziegler, 1988; Picha, 1996). The exact location of the North Apulian seaway in respect to the continental
fragments of the Central Tethys is still a matter of intense debate. Dercourt et al.
(1986), Scotese (1991), and Dercourt er al. (1993) relate this seaway to the Southern Apuseni and Pieniny Belt ophiolitic complexes, implying that during its opening Tisia
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. moved south, associated with Apulia. Ziegler (1988) interprets the aforementioned
ophiolitic complexes only as a limited intracratonic basin (Pienide-Transylvanian
basin), assigning to the North Apulian seaway a location south of the Tisia plate (Mid- Pannonian basin). A more extreme interpretation is that of Picha (1996), who
assigned both the Tisa plate and the central Carpathian units to the Apulian Plate. The Triassic and Early Jurassic location of the Tisa fragment, in respect to the
Paleo-Tethys (Cimmerian) ocean, is also a subject of controversy. It is generally accepted that during the Late Permian and the Triassic, rifting of the Neo-Tethys separated from the northern margin of Gondwana continental fragments that collided with Eurasia during the Late Triassic and Early Jurassic, as the Paleo-Tethys ocean closed (Sengor era/., 1980). Channel) & Kozur(1997) interpret the ophiolites and deep-water deposits of the Meliaticum zone from the Eastern Alps and Western Carpathians as part of the Cimmerian suture. Based on south Tethyan affinities of Triassic fauna and volcanism of the Tisia plate, the aforementioned authors conclude that Tisia was located south of the Cimmerian ocean, which completely closed during the Late Jurassic. Marcoux et al. (1993) provide a different interpretation of the location of the Tisia plate during the Late Triassic, north of both the Paleo-Tethys and of the Meliaticum zone. Geologic setting
The locations of the sections and wells investigated in the present study are shown in figure 1.3. The Munteana section is located on the Danube Valley, within the Danubian Autochthon of the Southern Carpathians. The Sinemurian and Pliensbachian (fig. 1.4) deposits of this section unconformably overlie Permian pyroclastics, and are conformably overlain by deposits of Toarcian age (Popa et al,
1976). The Lacu Rosu section is located on the Ghilcos stream, in the vicinity of the Lacu Rosu Lake, within the Bucovinic Sedimentary Suite of the Central Carpathian Unit of the Eastern Carpathians. The Sinemurian and Carixian (early Pliensbachian)
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. deposits of this section, investigated in this study, unconformably overlie Upper
Triassic limestones and dolostones, and are in turn conformably overlain by the
Domerian (late Pliensbachian) and Toarcian wackestones and packstones
(Sandulescu, 1975).
The Moneasa Quarry section is located within the Codru Nappe of the Northern Apuseni Mountains. The upper Sinemurian deposits of this section conformably
overlie rocks of Hettangian(?) - early Sinemurian age (lanovici et ai, 1976). The Pliensbachian deposits of the Moneasa Quarry section are unconformably overlain by Upper Jurassic clastic deposits. The sections at Garda Seaca and Piatra Bulzului are located in the Bihor Autochthon of the Northern Apuseni Mountains. In the Garda Seaca section, the late Sinemurian - Pliensbachian deposits are conformably overlain in both sections by the marly deposits of the Toarcian. The Bratca section is located in northwestern Romania, on the western flank of the Boiului Valley, in the Padurea Craiului Mountains (part of the Northern Apuseni Mountains), within the Bihor Autochthon tectonic unit. The Stmngulita section is located on the western flanks of the Bucegi Mountains, in the southern section (Leaota-Bucegi-Piatra Mare) of the Central Carpathian Unit of the Eastern Carpathians. The Middle Jurassic deposits of this section overlap Proterozoic crystalline schists. The Vinderei IP South well is located in the vicinity of the village of Vinderei, within the Barlad Depression (Scythian Platform). In this well, the Bathonian deposits unconformably overlie Triassic ones. The wells Caraorman West FI 1/7 and Crasnicol F61808 are located in the Danube Delta sector of the Predobrogean
Depression (Scythian Platform). The Caraorman West FI 1/7 well is located between
the Sulina and Sf. Gheorghe arms of the Danube, whereas the Crasnicol F61808 well
has a more southern position, in the immediate vicinity of the Sf. Gheorghe fault.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 0
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Fig. 1.3 Generalized tectonic map of Romania, showing the locations of the investigated sections and wells. '-j 8
Standard European ammonite tones Durmgitesspp. U Micracanthum POttfi M Fallawa TTTHONIAN Semtforme Darwini L Hybonotum Beckeri U Eudoxus VTN^^Dmrrr a m Acanthicum Divisum L Hypsetocyclum < PUttynota Planula U Bimammatum pditrcatum u rransversarium OXFORDIAN MPUeatila L Contatum Lomberti U Alhleta Coronamm CALLOVIAN W. Jason Gracilis L Macrocephalus Discus U Aspidoides y) Hodsoni m CAinUiNlAiN Subcontracms M PrograciUs a L Zigzag c/5 Partdnsoni u Garantiana o Subfurcamm BAJOCIAN Humpiuiesianum o L Lqimuscula < o Concavum U Murchisonae AALENIAN Scissum L Opalinum Pi Levesquei U Thouarsense Variabitis TOARCIAN M Bifrons Falcifirum ( = Serpentinus, p L Tenuicostatum U Spinatum PLIENSBA Domerian Margariuuus Davoei CHIAN Carixian Ibex L Jamesoni < . Raricostatum 1—1 U Oxynotum .STNF.MTIRTAN Obtusuai Tumeri Semcostatum L Bucklandi U Anguiata HETTANŒAN M Uasicus L Planorbis
Fig. 1.4 Subdivisions of the Jurassic period.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Previous studies So far only a small number of published studies have focused on the Jurassic
microfossils from Romania, and most deal only with taxonomy or biostratigraphy.
The presence of lower Liassic involutinid-domlnated faunas was reported by Patrulius (1964), Sandulescu (1969), and Grasu (1970) in the Lacu Rosu area (Eastern
Carpathians), and by Popa et al. (1982) from the Central Bihor area (Apuseni Mountains). The synthesis of lanovici et al. (1976), conceming the Apuseni Mountains, includes some micropaleontological data, regarding mainly involutinids. No works have been published yet on Toarcian microfossils from Romania; one study has been completed on the Bajocian material from Strungulita by Neagu et al. (1983) and one on Bajocian - Bathonian from the western part of the Moesian Platform by Costea & Motas (1964). Somewhat more micropaleontological data are available on the Upper Jurassic carbonate deposits. The Upper Jurassic calcareous algae and foraminifera of the Eastern Carpathians were described by Dragastan (1975), Bucur (1977), and Sorescu ( 1986). The Upper Jurassic microfauna of the Northern Apuseni Mountains was investigated in thin sections by Manea & Serini (1980), Dragastan et al. (1986), and Bucur (1988). Dragastan & Neagu (1975) have achieved an overview of existing data conceming the micropaleontology of Jurassic deposits from Romania. Dragastan ( 1980) provided data on the calcareous algae and foraminifera of carbonate platforms from the Eastern and Southem Carpathians. Microfauna of Tithonian deposits from the Moesian Platform was investigated in thin sections by Dragastan (1985). A study on foraminifera (detached material) from the upper Oxfordian-lower BCimmeridgian of Central Dobrogean Massif was completed by Barbulescu & Neagu (1970). Neagu & Neagu (1995) have investigated Kimmeridgian agglutinated foraminifera from the Eastern Carpathians. Data on ammonites and miliolid foraminifera from the
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Predobrogean Depression (southem Moldova and southwestern Ukraine) are provided by Romanov & Danitch (1971).
In previous works, microfossil biozones, based on foraminifera, algae, calpionellids, saccocomiids and tintinnids were proposed only for the Kimmeridgian -
Tithonian interval by Dragastan et al. (1973) for the central-western part of the Moesian Platform and Dragastan (1975) for the Rarau-Haghimas area. Eastern
Carpathians, Transylvan nappes system). Costea & Motas (1964) have defined biozones in the Dogger of the western part of the Moesian Platform. The biostratigraphy of the classic Munteana section has been investigated for over 120 years, the most recent and comprehensive study being that of Popa et al. (1976). However, none of these studies have focused on the microfauna of this section. The geology and biostratigraphy of the Lower Jurassic deposits firom the Lacu Rosu area have also been investigated by many authors, the most recent and important studies being those of Grasu & Turculet (1967) and Sandulescu (1975). Data conceming foraminifers from these deposits are provided by Atanasiu & Raileanu (1950), Patrulius (1964), conceming foraminifers from the Trotus Valley, where the facies of the Sinemurian-Pliensbachian deposits is very similar to that of the neighboring Lacu Rosu area), and Grasu (1970). As far as the Moneasa, Garda Seaca and Piatra Bulzului sections are concemed, an overview of the biostratigraphy of these areas, including a brief summary of foraminifer data, is provided by lanovici et al. (1976).
Additional biostratigraphic data, including foraminifers, are given by Popa et al. (1982) for the Garda Seaca and Piatra Bulzului sections. The ammonite biostratigraphy of the Toarcian deposits fi*om Bratca was studied by Popa (1968); an overview of the ammonite zones identified in the Bihor
Autochthon is provided by Patralius & Popa (1971) in a synthesis for the Romanian Carpathians and by lanovici et al. (1976) in a synthesis for the Apuseni Mountains. These studies, based on the ammonite biozone scheme proposed by Dean et al.
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(1961), identified in the deposits of this tectonic unit all of the Toarcian ammonite
zones. The classic section of Strungulita, one of the richest in Jurassic fossils in
Romania, has been investigated for over 135 years. A review of these investigations is provided by Mutihac & lonesi (1974). The most recent studies are those of
Patrulius (1969), conceming litho- and biostratigraphy based on macrofossils and Neagu et al. (1983), focusing on biostratigraphy based on microfossils. The most important studies conceming the geology of the Bigar area are those of Raileanu (1960) and Iordan (1966); Mutihac & lonesi (1974) provide an overview of previous investigations. The lithostratigraphy and biostratigraphy of the upper Bathonian-lower Callovian deposits of the Central Dobrogean Massif have been investigated by Barbulescu (1971). This author mentions the main features of the foraminifer and ostracod assemblage of these deposits, without species identifications. The Middle and Upper Jurassic deposits of the Barlad and Predobrogean Depressions (Scythian Platform) are known only firom petroleum exploration wells; their lithostratigraphic and biostratigraphic results are summarized by MutihacSc lonesi (1974). More complete lithostratigraphic and biostratigraphic data conceming the Upper Jurassic deposits of the Danube Delta sector of the Predobrogean Depression, based mainly on microfaunal (foraminifera) content are included in a study by Patmt et al. (1983). Data conceming the ammonites and miliolid foraminifera of Middle and Upper Jurassic deposits of the Predobrogean
Depression from southem Moldova and southwestem Ukraine are provided by Romanov & Danitch (1971). Important references in the fields of Jurassic foraminifera and ostracods, biostratigraphy, paleobathymetry, paleobiogeography, eustasy, and paleotectonic reconstructions are listed in table 1.1.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2. MATERIALS AND METHODS
Material and sample preparation The stratigraphie intervals coveted by the sections and wells investigated in the present study are shown in figure 2.1. Most samples from the Munteana and Moneasa sections were collected by the author of this study. Samples 11,12,305, 306,317,319, D, E, and F from Munteana, sample 5 from Moneasa, and all the samples from Garda Seaca and Piatra Bulzului are part of the Popa-Patrulius- Dragastan collection. Samples from sections at Munteana, Lacu Rosu, Moneasa, Garda Seaca, Piatra Bulzului, and some samples from the well Caraorman West FI 1/7 have been studied in thin sections. Remaining samples, including a small number from the Munteana sections, have been investigated as detached material. In the case of outcrop samples, in order to minimize the potential bias due to unequal lateral distribution of the microfauna, the samples are collected over a lateral distance of 5-6 m. The wells Caraorman West FI 1/7 and Crasnicol F61808 were completely cored, whereas only three isolated cores from the well Vinderei IP South were available. Out of each outcrop sample, 400 g of dry rock (250 g in the case of the borehole cores) was processed by being crushed in a mortar and then repeatedly boiled in a sodium sulfate and sodium carbonate solution. The samples were then washed on a 80 micron sieve, and the resulting residue was completely picked. Both absolute and relative counts were conducted for all foraminifera and ostracods. In the case of ostracods, the number of specimens was estimated as the number of carapaces plus the number of left or right valves, whichever count was the larger. Microfaunal parameters
The microfaunal parameters used in the present study are diversity, heterogeneity, absolute abundance, percentage of microfaunal fragmentation, and rate of faunal
12
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change. Diversity was considered in its simplest form, as the number of foraminifer
or ostracod species in each sample (Murray, 1991). The index of heterogeneity used
is represented by the Shannon-Weiner information function:
H(S)=-E pùnpi where “S is the number of species and pi the proportion of the Ah species (p = per
cent divided by IOÔ)” (Murray, 1991). The rate of faunal change for each sample is
expressed as the number of species occuring in the sample for the last time in the stratigraphie succession, subtracted from the number of species occuring for the first time. Quantitative analysis Cluster analysis is the quantitative method used to identify biofacies. According to Hazel (1970), a quantitative coefficient is best suited as a measure of similarity in this case. In this study the measure used is the Euclidean distance, the distance between two clusters being defined as:
DiCL=nXic-XLlP
wherexk is the mean vector for cluster Ck - The dendrograms using this measure
of similarity were generated by means of the IMP Statistical Software for the Macintosh from S AS Institute Inc. For this type of analysis only the main components (Brouwer, 1969) were taken into account, that is, for each sample only those species representing at least 5% of the total number of specimens. In the Bratca section this type of cluster analysis resulted only in the identification of two broad biofacies units. Additional Q-mode cluster analysis with the values for foraminifera diversity, heterogeneity and percentage of fragmentation as parameters was used in
this case to refine the biofacies division into subunits. To lessen the effect of rare species as well as that of possible faunal mixing or displacement, only species that occur in at least a certain percentage of the total number of samples (25% for the
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Bratca section, 20% for the Caraorman West FI 1/7 well) were used. This threshold
is comparable to that of 20% used by Nyong & Olsson (1984) and that of 30% used
by Sikora (1991).
R-mode cluster analysis using as parameters the relative abundance of the
foraminifer main components was used in order to understand the relationships between the biofacies units and the species that define them. The resulting
dendrograms were interpreted together with the average values of the relative frequency of each species within the samples of each unit.
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■D CD N APUSENI EASTERN SOUTHERN SCYTHIAN C/) CENTRAL C/) MOUNTAINS CARPATHIANS CARPATHIANS PLATFORM DOBROGEAN BIhor Codfu Ccnirol Donubian Bttrlod Pretkbrogcim MASSIF Autochthon nappes Cofpaihion Unit Autochthon Depression Depression TITHONIAN 8 KIMMERIDGIAN (O' < s II u OXFORDIAN I lf M CALLOVIAN K 1 3"3. p< H 11 CD CA w BATHONIAN i f ■DCD o y a . O (Ao Q. BAJOCIAN C o a o f 1 o < CO 3 AALENIAN i? "O o W TOARCIAN 1 CD Q. PUENSBA- Domerian Vi CHIAN Carixian < I t—( 1 ■D SINEMURIAN 1 CD æ 9
C/) C/) HETTANGIAN
Fig. 2.1 Stratigraphie intervals covered by the investigated sections and wells. Ui 3. SINEMURIAN - PLIENSBACHIAN (LOWER JURASSIC) FORAMINIFERA AND OSTRACODS FROM ROMANIA
Lithology
The Munteana section is located on the Danube Valley, within the Danubian Autochthon of the Southern Carpathians (fig. 1.3). The Sinemurian and
Pliensbachian deposits of this section unconformably overlie Permian pyroclastics, and are conformably overlain by deposits of Toarcian age (Popa etaL, 1976) (fig. 3.1). The deposits assigned to the early Sinemurian by Popa et al. (1976), are 15 meters thick and consist of white quartzitic sandstones with intercalated gray shales. The upper Sinemurian and lowermost Pliensbachian deposits are represented by 10 meters of red and gray, bioclastic, oolitic (hematitic and chamositic) wackestones. The remaining part of the Pliensbachian deposits (45 meters) consists of alternating gray bioclastic wackestones and packstones, with thin intercalatated shales (Popa et al., 1976). The Lacu Rosu section is located on the Ghilcos stream, on the banks of the Lacu Rosu Lake, within the Bucovinic Sedimentary Suite of the Central Carpathian Unit of the Eastern Carpathians (fig. 1.3). The Sinemurian and Carixian (early Pliensbachian) deposits of this section, investigated in this study, are represented by red oolitic and bioclastic wackestones (tig. 3.1). These deposits, 7 meters thick, unconformably overlie Upper Triassic limestones and dolostones, and are in turn conformably overlain by the Domerian (late Pliensbachian) and Toarcian wackestones and packstones (Sandulescu, 1975). The Moneasa (Juarry section is located within the Codru Nappe of the Northern
Apuseni Mountains (tig. 1.3). The upper Sinemurian deposits, consisting of 12 meters of black encrinal limestones, conformably overlie the gray and black wackestones of the Hettangian(?) - early Sinemurian (lanovici et al., 1976). The Pliensbachian deposits (18 meters thick) are represented by red, subnodular, breccioid
16
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limestone ("Moneasa marble"), unconformably overlain by Upper Jurassic clastic
deposits.
The sections at Garda Seaca and Piatra Bulzului are located in the Bihor
Autochthon of the Northern Apuseni Mountains (fig. 1.3). In the Garda Seaca section, the late Sinemurian - Pliensbachian deposits, with a thickness of 10 meters,
consist of gray wackestones and quartzitic sandstones, followed by limestones with
levels including ferruginous ooids, the latter being also present in the Piatra Bulzului section (3 meters). The Pliensbachian deposits are conformably overlain in both sections by the marly deposits of the Toarcian.
Biostratigraphy The biostratigraphy of the study sections, as established in previous works (fig. 3.1), is based mainly on macrofossils (brachiopods, ammonites, belenmites and bivalves). Palynological assemblages were used in the case of Munteana section, for lower Sinemurian deposits interpreted as non-marine (Popa etaL, 1976). Ammonite zones have been identified only for Pliensbachian deposits, in sections Munteana (Popa et al., 1976) and Garda Seaca (Popa et a l, 1982). The biostratigraphy of the Munteana section, as summarized by Popa et al. (1976), raises a special question concerning the deposits attributed to the Sinemurian (fig. 3.1). The first anunonites have been recovered in this section by the aforementioned authors from the upper part of the red oolitic wackestones, indicating theJamesoni zone (earliest Pliensbachian). The brachiopod assemblages from the lower part of the red oolitic limestone, as well as the palynological assemblages from the underlying sandstones and shales indicate an undifferentiated Sinemurian age. These two units have been assigned to the late and early Sinemurian, respectively
(Popa et a i, 1976) only based on their superposition relationships. If the succession of these deposits is viewed from the standpoint of sequence stratigraphy, one may suggest that the deposition of all the Sinemurian formations
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from the Bratca section, on top of a major unconformity, is related to a single interval
of major eustatic sea-level rise, probably corresponding the late Sinemurian
transgression (Hallam, 1988; Haq e ta L , 1988).
The foraminifera recovered from the study sections are represented by
involutinids, nodosariids, textuiariids, and ceratobuliminids. However, only involutinids can be identifîed at the species level in thin sections. The biostratigraphic
resolution of this group is low, but it can provide valuable data for deposits devoid of ammonites. Ranges for the microfossils recovered in the investigated sections are shown in figure 3.2. The microfossil assemblages are listed in Appendix B.
The total known range of the foraminifer species Involutina liassica is Upper Triassic-Toarcian (Scheibnerova, 1968; Copestake & Johnson, 1989; Blau, 1991). In the Lower Jurassic of Romania its latest occurrence is in Domerian deposits of the Apuseni Mountains (Garda Seaca, Piatra Bulzului), but in the Southern and Eastern Carpathians (Munteana, Lacu Rosu) the range of this species is restricted to the late Sinemurian. A small number of involutinid specimens, tentatively assigned to species of the genus Aulotortus (A. cf. A .friedli and A.? ex gr. sinuosus) were recovered from the Munteana section. According to most authors, the total range of this genus is known to be restricted to the Middle and Late Triassic, and some species, such as Aulotortus friedli, are considered to be index fossils (Gazdzicki, 1983) for the Rhaetian (latest Triassic). A few references have been made as to the presence of representatives of this genus in the lowermost Liassic (Zaninetti, 1976; Filler, 1978; Gazdzicki, 1983), but at least in some cases this might be due to poor time control of the respective deposits (Blau, 1995, personal communication). The possibility that the forms found
in the Munteana section might be rewoilced from Triassic deposits can be safely excluded, as the Sinemurian deposits of this section unconformably overlie Permian
pyroclastics. Triassic deposits are also absent from the entire Svinita-Svinecea area of
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the Danubian Autochthon sedimentary cover, where the Munteana section is located
(Mutihac & lonesi, 1974).
The foraminifer Ophthalmidium leischneri is considered as an index fossil by
Gazdzicki (1983), its stratigraphie range in the Western Carpathians being Hettangian
- ?Sinemurian. The range of this species extends in the Pliensbachian, as shown by
the results of the present study (Munteana and Garda Seaca sections) and by Popa et al. (1982) in the Garda Seaca section. Paleoenvironments The lithology and microfaunal content of the upper Sinemurian - lowermost
Pliensbachian deposits of Munteana, Lacu Rosu and Garda Seaca sections display strong similarities. These deposits are represented by bioclastic wackestones with ferruginous ooids, to which a clastic component consisting of fine-grained, rounded quartz grains is added in the Munteana section. Among the involutinids, the foraminifer assemblage is dominated by large forms, such as Involutina liassica and Trocholina umbo. These deposits lack ammonites, but brachiopods, echinoderms and bivalves are abundant.
The presence of ooids as well as the large amount of echinoderm and brachiopod debris, usually well-rounded, point to the high energy level of the environment, typical of the subtidal zone. Algal coatings of foraminifer tests and other bioclasts represent evidence for shallow-marine conditions in the photic zone. The presence of a clastic component in the carbonate rocks of Munteana indicates the proximity of the shore. A detailed pétrographie analysis of the ferruginous (chamositic and hematitic) ooids from Munteana allowed Rusu (1968), to describe the depositional environment of these rocks as the inner shelf, where freshwater input from the continent lowers the
pH to values favorable for the precipitation of iron oxides and silicates. In the Munteana section, ammonites belonging to the Jamesoni zone (earliest Pliensbachian) have been found at the very top of the red oolitic wackestones (Popa et
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al., 1976). This level probably represents the deepest waters during the deposition of
the ferruginous wackestones, and is followed by 3 meters of quartzitic sandstone.
This sharp change in lithology suggests a sea-level fall. Quartzidc sandstone in the Munteana section is overlain by Pliensbachian
bioclastic wackestones and packstones, with thin intercalated shales. The detached microfauna found in the shale levels indicates normal marine, neritic environments. These deposits have yielded ammonites and may be interpreted as representing shelf deposits, formed in somewhat deeper waters than the preceding oolitic wackestones. The microfauna of the carbonate intervals is dominated by the genera Coronipora, Semiinvoluta and Spirillinal. A common trend in the succession of paleoenvironments can therefore be traced in the Munteana and Garda Seaca sections (and partially in Lacu Rosu). The nonmarine clastic deposits attributed to the lower Sinemurian are overlain by shallow marine upper Sinemurian oolitic wackestones, followed by the ammonite-bearing deposits of the lower Pliensbachian. As shown by the succession of paleoenvironments identified in the present study, the general trend for the Sinemurian - early Pliensbachian time interval for the Munteana, Garda Seaca, and Lacu Rosu sections is that of a relative sea-level rise. This corresponds only in part to the pattern of eustatic sea-level variation proposed by Hallam (1988) and Haq et al. (1988). Both authors recognize a sea-level rise during the late Sinemurian, but interpret a sea-level fall at the Sinemurian - Pliensbachian boundary. The quartzitic sandstone overlaying the oolitic wackestone in the Munteana section might correspond to this sea-level fall, but nevertheless an offset of the maximum flooding surface (representing two ammonite zones) exists between the interpretation of the Munteana section and the eustatic curves proposed by the aformentioned authors.
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■D CD I GARDA PIATRA C/) TOAR MUNTEANA C/) CIAN SEACA BULZULUI
MWEASA SAMPLES SAMPLES •177 ■IS ■D8 a a SAMPLES
-0/9: -N/9Î •191 SAMPLES LACU ROSU m -K/92 WWsW 3"3. SN SV sW N CD en -15/91 NNNWVSS NWSSSW SAMPLES en U/91 ■DCD O < I Q. m m calcareous sandstone C V.V.V.V,,;- a 155 I gray, bioclastic O I wackestone and pnckstone 3 P "O I quaitziiic sandstone O //////// t //////// shale V/////////J red bioclastic, CD oolitic wackestone Q. (/) I pyroclastics IsNWS'l t=d wackestone li 11 ■ ■ il and packstone limestones ■D and dolomites CD To = Toarcian 1 = lower red, subnodular, breccioid I Do = Domerian 2 = middle limestone ("Moneasa marble") C/) C/) Cx = Carixian 3 = upper black encrinal limestones Si = Sinemurian PERMIAN r ” ”" '! gray and black wackestone IV Fig. 3.1 Lithology and stratigraphy of the Munteana, Lacu Rosu, Moneasa, Garda Seaca, and Piatra Bulzului sections. 22
HFTTAN SINEMURIAN PLIENSBACHIAN TOAR GIAN Carixian I Domerian CIAN
Ammodiscus ip .
~Textularia~ sp. llZllilllllllllllllillllllll I MO •• Cbmo^jnaa_sg^\_
IlSlilllllllllllllllllllllll Involutina liassica I M Q:
TrochoUna tunpo
TrochoUna turns
lAulolortttS e x nr. sinuosus Aidomniaj^^^içM^ Semiinvoluta clari Semiinvoluta viotae Semxinvohüab^xmnaïa Cororupora austnaca Corompora etrusca Corontpora gusici £ iSpinU ata sp MO
Tttrrispiriluna sp . I -■ MO " - ‘-r Ophthalmidium martanum
Ophtfialmtdium leischneri
Ophthalmidium carinatum
Ophxhamxdium sp. Ichteolaria bnzaeformis Nodosana sp Ungutma^a^g^jme^
Lenticulina sp. S.L (mg Lenticulina, MO mg MarginuUnopsis ) » • n% -rrrri icaiiiiiiiiiiiiiiiiiiiiiiii 'Epistomina ’ sp. MO : L-GS- ^Paradamuma^uÆm^ Oanoeondut coraractula OgmaeondiMajÿ^ MU Munteana section Piatia Bulzului section lllutl II Lacu Rosu section I MO I Moneasa section o s j Garda Seaca section Fig 3.2 Range charts for the microfossil species identified in the Munteana, Lacu Rosu, Moneasa, Garda Seaca, and Piatra Bulzului sections. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 23 The Sinemurian - Pliensbachian deposits of the Munteana, Garda Seaca and Piatra Bulzului sections are developed in a facies similar to the Gresten facies' of the Oriental Alps (Popa et a i, 1976; lanovici et a i, 1976). The lower Liassic from Lacu Rosu is attributed to the Hierlatz facies^ of the Oriental Alps (Grasu & Turculet, 1967), although the late Sinemurian - Carixian deposits of this section are extremely similar to those of Munteana and Garda Seaca. The Gresten facies, corresponding to the external (northern) areas of the Northern Calcareous Alps, is interpreted as indicating "the direct approach to a granitic coast", whereas the Hierlatz facies, corresponding to more internal (southern) areas, is thought to correspond to submarine ridges (Brinkmann, 1960). The Sinemurian - Pliensbachian deposits of the Moneasa section lack a clastic component, have yielded abundant belemnites and brachiopods, and were probably deposited in deeper waters. According to lanovici et al. (1976), the macrofauna of these deposits is of Gresten type, but the facies is typical for the Adneth limestones'. The Adneth limestone, representing inner (southern) areas of the Northern Calcareous Alps is interpreted as corresponding to troughs (Brinkmann, 1960). During the Triassic, the involutinids included only forms with undifferentiated umbilical masses and lived in shallow, warm and well oxygenated waters, within the subtidal zone. Forms with pillars (including Involutina liassica and Trocholina umbo) first appeared at the end of the Late Triassic, being found in marls and mudstones with ammonites and pelagic bivalves (Zaninetti, 1976). These deposits suggest a ' The Gresten facies (Lias) consists of calcareous sandstone and coarse-grained arkose, with thin intercalated carbonaceous shales and coal seams, replaced at higher stratigraphie levels by argillaceous sandstone, breccioid limestone and sandstone with brahiopods, bivalves, and rare ammonites (Tataram, 1984). ^ The Hierlatz facies (early-middle Lias) consists of white or reddish limestones with abundant crinoids, as well as brahiopods, bivalves, and gastropods (Tataram, 1984). ' The Adneth facies (Lias - early Dogger) consists of red nodular, ammonite-rich limestones (Tataram, 1984). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 24 "basinal" environment, deeper than the carbonate platform and also apart from any continental and littoral influences (Zaninetti, 1976). The involutinids with undifferentiated umbilical masses, inhabiting shallow waters, became extinct at the end of the Triassic. Liassic involutinids are known to be represented only by forms with pillars (Involutina, Trocholina, Coronipora and Semiinvoluta). The major factor that led to these changes is represented by the disintegration of the carbonate platforms of the western margin of the Neo-Tethys due to the rifting of the North Apulian seaway (Blau, 1991). Another factor, probably connected with the first one, is the Liassic transgression that limited the reefal environments to which the smooth involutinids were adapted (Zaninetti, 1976). The present study identified Liassic representatives of the genera Involutina and Trocholina not only in deeper water depositional environments (Moneasa section), but also in shallow waters, high energy environments (Munteana, Lacu Rosu, Garda Seaca, and Piatra Bulzului sections). The latter occurrence - similar to those reported by Gazdzicki (1975) and Blau (1991) - together with the large size of the specimens, indicates that during the Liassic the involutinids have succeeded in recolonizing the high-energy, shallow waters of the subtidal zone. They also became more tolerant of higher levels of clastic input. Representatives of the genera Coronipora and Semiinvoluta were found in the present investigation not only in deeper water deposits, as previously reported by 2^inetti (1976) and Blau (1991), but also in shallow waters, high energy environments (upper Sinemurian of the Munteana section). Paleobiogeography The investigated deposits of the Southern Carpathians, Eastern Carpathians, and Apuseni Mountains belong to facies types (Gresten, Hierlatz, Adneth) widely developed in the Oriental Alps (Northern Calcareous Alps) and the Western Carpathians. The involutinid assemblages identified in the present investigation Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 23 closely resemble those described from Sinemurian - Pliensbachian carbonate deposits located throughout the Tethyan realm (Gazdzicki 1975,1983), on both its northern and southern margins. Species belonging to the genera Involutina and Trocholina, and especially Involutina liassica, also have a wide distribution in the Liassic deposits of the European epicontinental basin (Exton & Gradstein, 1984; Copestake & Johnson, 1989; Blau, 1991). Involutinids are therefore of little use for paleobiogeographic purposes. The distribution of large benthic foraminifera with complex structure in carbonate facies during the Sinemurian and Pliensbachian allowed the derinition of a province characterized by the presence of species of the genus Orbitopsella, as well as of the species Labyrinthina recoarensis, Mayncma termieri, Haurania ex gr. amiji-deserta, and Pseudocyclaniminaliasica(Basso\il\et etaL, 1985). This bioprovince corresponds to the southern Tethyan margin, located during the Early Jurassic at paleolatitudes between 0 and 30 degrees N, extending from Morocco to Oman. During the same time interval, the northern Tethyan margin, located at paleolatitudes higher than 30 degrees, was characterized by the absence of large benthic foraminifera with complex structure, likely to be explained in the case of similar carbonate facies by climatic incompatibilities. The only known record of one of the aforementioned species on the territory of Romania is that of Pseudocyclammina liasica, in the upper Sinemurian - lower Pliensbachian deposits of the Bihor Autochthon of the Apuseni Mountains (Popa et a i, 1982). No large benthic foraminifera with complex structure were recovered during the present study. The complete absence of representatives of this foraminifer group in the investigated Liassic deposits of the Eastern and Southern Carpathians clearly indicates that the corresponding tectonic units (the Central Carpathian Unit and the Danubian Autochthon) were part of the northern Tethyan margin during the Early Jurassic. The Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 26 isolated presence of Pseudocyclammina liasica in the Liassic deposits of the Apuseni Mountains, in the absence of any other species considered diagnostic for the south- TethyanOrbitopsella province, can be regarded as evidence for a wider geographic range of this species than previously known, rather than for a south-Tethyan location of the Apuseni Mountains during the Early Jurassic. Further evidence of north- Tethyan faunal affinities of the Liassic deposits of the Apuseni Mountains is provided by the brachiopod assemblage from the Pliensbachian of Moneasa, similar to that of the Franco-Swabian basin (lanovici et al., 1976). Similarities between the Lias foraminifer assemblages of the Western Carpathians and those of typical northwestern European epicontinental deposits have been noted by Gazdzicki (1975,1983). Such similarities are also obvious in the case of the detached microfauna identified during the present investigation in the marly levels in the upper Sinemurian - Pliensbachian of Munteana section (Southern Carpathians). The ostracod species Paradoxostomal pusillum and Ogmoconcha contractula are known only from Liassic deposits of the epicontinental basin of northwestern Europe. The foraminifer species Ichtyolaria briza^ormis and Lingulina tenera are considered as characteristic species of Boreal Lower Jurassic assemblages in Europe by Copestake & Johnson (1989). However, the abundant presence of forms belonging to the Lingulina tenera group has been recently reported in the Liassic marly deposits of the southern Tethyan margin (Bartolini etaL, 1992), which have been comparatively less subject to investigation. Detached microfauna was also found in marly levels of the upper Sinemurian - Pliensbachian deposits of the Bihor Autochthon of the Apuseni Mountains (Valea Vulturului section) by Popa et al. (1982). This microfauna consists of a nodosariid- dominated assemblage and includes species that have been described in the Liassic epicontinental deposits of northwestern Europe. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4. TOARCIAN (LOWER JURASSIC) FORAMINIFERA AND OSTRACODS FROM BRATCA, NORTHERN APUSENI MOUNTAINS, ROMANIA Biostratigraphy The Bratca section is located in northwestern Romania (fig. 1.3), on the western flank of the Boiului Valley, in the Padurea Craiului Mountains (part of the Northern Apuseni Mountains), within the Bihor Autochthon tectonic unit The Serpentinus (= Falciferum) ammonite zone was not identified in the deposits of Bratca section. However, this ammonite zone was identified in many other locations in the Padurea Craiului Mountains - Mnierii Valley, Vadu Crisului, Coasta Cailor, Marches Valley (lanovici et aL, 1976), the lithology of the Tenuicostatum-B^ons interval being similar in these sections to that of Bratca. Given also the fact that no unconformity could be recognized in the Bratca section at this level and that the deposits belonging to the aforementioned interval are interpreted as open marine, it appears safe to presume that theSerpentinus biochronozone is represented in the Bratca section. However, under these circumstances the upper boundary of the Tenuicostatum zone is only tentatively set between samples 189 and 188 (fig. 4.1). The interval thought to represent the Serpentinus biochronozone is referred to as the ISerpentinus zone. The stratigraphie occurrence of a significant number of foraminifer and ostracod species is limited in the Bratca section to sample 189, corresponding to the Tenuicostatum ammonite zone (fig. 4.2, table 1.2). These species include Marginulina prima^ Vaginulma listi, Ichtyolaria intumescens, Lenticulina speciosa, L aragonensis, Lenticulina sp. D, Lenticulina sp. nov. of Ruget (1985) among foraminifera and Ogmoconchella adenticulata, O. aequalis, and Ogmoconcha sp. A of Boomer (1992) among ostracods. The extinction at the boundary of the Tenuicostatum and Serpentinus zones of forms inherited fiom the Pliensbachian is considered to represent "the most marked microfaunal turnover of the Early Jurassic" (Copestake & Johnson, 1989) and is recognized throughout western Europe (Ruget, 27 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 28 1980, 1988, 1985; Copestake & Johnson, 1989). Sample 189 is therefore considered in the present investigation to represent the lowermost biostratigraphic unit (A) in the Bratca section. The foraminiferai assemblages of samples 188 to 183 are characterized by a renewed microfauna including species of the genus Citharina (C. clathrata, C. longuemari, C. colliezi), Lenticulina bochardi, L. obliqua, L. deslongchampsi, L. pennensis, L. obonensis, and Lenticulina sp. B (fig. 4.2, table 1.2). These samples are interpreted in the present study as representing a second biostratigraphic unit (unit B). Although the first specimens of Lenticulina chicheryi were recovered from the Tenuicostatum zone (unit A), this species becomes abundant only in the deposits of unit B. The presence of Ichtyolaria sulcata (= Frondicularia terquemi sulcata) in the lowermost part of the ISerpentinus zone is one of the latest records for this genus, known to have not survived the extinction at the Tenuicostatum-Serpentinus boundary. Samples 182 through 171 represent a third biostratigraphic unit (Q . The foraminifer species Lenticulina d ’orbigny occurs for the first time in sample 182, corresponding to the upper part of the Bifrons ammonite zone (fig. 4.2, table 1.2). The boundary between units B and C seems to also correspond to a gradual paleoenvironmental change that resulted in the local extinction of a large number of foraminifer species. Some species, such as Citharina longuemari and C. colliezi, become extinct immediately below the boundary, whereas Citharina clathrata, Lenticulina chicheryi, L. deslongchampsi, L. obliqua, Lenticulina sp. B, Pseudonodosaria multicostata, P. vulgata, Dentalina nodigera, and Lenticulina polygonata occur for the last time at lower levels of the Bifrons ammonite zone (table 1.2 ). Among the important ostracod species, only the distribution of Bairdiacypris triangularis matches the extent of unit B, whereasCytherella praetoarcensis was found Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 29 only at its base (fig. 4.2, table 1.3). Liasina lanceolata and Trachycythere tubulosa, already present in unit A, disappear after the lower part of unit B (below the base of Bifrons zone), being replaced by species such as Bairdiacypris rectangularis, Ektyphocythere intrepida, and Wellandia faveolata. Unit C is marked by only one new occurrence of a foraminifer species - Lenticulina d'orbignyi, recovered in the Bratca section beginning with the Bifrons zone, which coincides with the consistently reported first appearance in western Europe (Copestake & Johnson, 1989), suggesting that it is not a merely paleoenvironmentally-driven occurrence. New ostracod occurrences in this unit are Cytherella toarcense, Ektyphocythere debilis, and Cytherelloidea sp. A, whereas other species present, such as Bairdiacypris rectangularis and Kinkellinela sermoisensis already appeared in the upper part or the top of unit B. A comparison of ranges for selected foraminifer and ostracod species from Bratca section to those recorded in the literature (fig. 4.2) shows that most species are long ranging, with significant geographic variations, and therefore generally of low value for a biostratigraphic approach based on range zones. The approach taken in this study in defining a biozonation for the Bratca section is based on assemblage zones (cenozones), as defined by ISSC (1976), and using as much as possible species of both foraminifera and ostracods whose first or last occurrences represent events with a high degree of synchrony over large areas, such as the extinctions occurring at the Tenuicostatum-Serpentinus boundary and the new occurrences following it, and the first occurrence of Lenticulina d'orbignyi in the upper part of the Bifrons zone. The assemblage zones for the Bratca section, corresponding to the previously described biostratigraphic units and listed below, are compared to biozonations by previous authors in figure 4.3. Lenticulina aragonensis assemblage zone (biostratigraphic unit A) Definition: defined by the presence of the characteristic species Lenticulina aragonensis, Lenticulina speciosa, Lenticulina sp. nov. of Ruget (1985), Lenticulina Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 30 sp. D, Marginulina prima, Ichtyolaria intumescens, Ogmoconchella adenticulata, O. aequalis, and Ogmoconcha sp. A of Boomer (1992). RangezTenuicostatum ammonite zone Remarks: This assemblage zone is equivalent to the uppermost part of the Marginulina prima plex. interrupta zone of Copestake & Johnson (1984) and may be considered a subzone of the latter. The worldwide known range of the species Lenticulina aragonensis is restricted to the Tenuicostatum zone, making it a very useful regional marker. Citharina clathrata assemblage zone (biostratigraphic unit B) Definition: defined by the presence of the characteristic species Citharina clathrata, Lenticulina obliqua, L. deslongchampsi, L chicheryi, L. pennensis, L. obonensis, Citharina longuemari and Bairdiacypris triangularis. Range: ISerpentinus and the lower part of the Bifrons zones Remarks: This assemblage zone corresponds to the VaginulinalCitharina clathrata gr. of Copestake & Johnson (1984), when the latter's upper boundary is located within the Bifrons zone. Lenticulina d'orbignyi assemblage zone (biostratigraphic unit C) Definition: defined by the presence of the characteristic species Lenticulina d'orbignyi, L muensteri, L acutiangulata, L bochardi, Bairdiacypris rectangularis, Kinkelinella sermoisensis, and Cytherelloidea sp. A. Range: the upper part of the Bifrons, the Variabilis and Thouarsense ammonite zones. Remarks: This assemblage zone corresponds to the lower part of the Lenticulina dorbignyi zone of Copestake & Johnson (1984). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ■DCD O Q. C g Q. ■D CD C/) 3o" FORAMINIFERA 1 I OSTRACODKSl INFERRED REUTIVe PRESERVATION OIVER- HETERa FIRST OCC.« FRAGMENTED ABUN- «VER. FIRST OCC. ^ I T E S SEA-LEVEt VARIATIONS O einllenl ma GENETTY LASTOCC. SPECIMENS DANCE SITV LASTOCC IN BRATCA SECTION » «Koïkmar^fmfKVH middle neriiic ■D8 3. 3" CD ■DCD O Q. C Oa 3 ■D O H4KNS. (wi. of (mi. of RACIIIAN ipcclme») apocks) •ocvimcm) CD TR " tninsgrfMivc lyMcmi (racl Q. Îlimestone I maximum flooding aurfacc with cfteit mKa" rassïïï™ HS n high-stand syilemi Iract m i l wqucncc boundary "O CD C/) C/) Fig. 4.1 Lithology and microfaunal parameters of Bratca section. UJ 32 îfl II 0c itiuiiiimi I 1 y'tis eeptooBjam^ C3 ajqap BjaiffAooqdAvg 1 sfsuaajeoi eiiajamÀo "Il oa sisuasiouuas BuauijBSfuoi "Il B sueinBueiaaj sudAoapj^ "Il ê o efxdajiw Bjetft^ooqdApg 2 8 efeioeABf eipueiiBM «yuuiui» i g suBinBuBui sudÆaetpj^ "ll|||" myiiiiiiiiiiiiiiiiuiuiimyii g- k s/suaawotajd ei/ajodiAo ■§ o Bsoinqm ejaqiAoAtpBtj, iinmiiniiiniiiu Uinininiiniiiii eie/oeouef euisen puiuuui iiiniiiniiii Ë s c66iTQWCX)avcfeBtpwooouiÉb •a suenbaeeuaqouoootuèo uiiiiiiniiiiiiiiii § eiBinoiiuepBegaqauoaouiBo w t/uBiqjoj) euunoiiuej IZBUIOO 'c £ pjeuooq etnjnoiiua-f C3 UBW9nBuo( euuequo mimimimmn BfejufBa Butwquo tsdtuetpBuotsap etifinoituaq 1 enbttqo eunnonuaq ë sisuBuoqo eut/nonua-j 1 sisuBuuad eugnotjua-j a eveains euBioAiqot iiiiiiiiitmiiiiiiiiiiitiiitiiittiii eiBinBuennoB eugnoi;uaq uaisuanut Bugnaiiuo-i niiiitiiniiiiiniuuiimuiimmniiiiiiij||||n. U lAïaqoiqo eugnaiiua-i "ll|||l""' & BfBtsooignuiBUBsopouopnasij ______suaosauiniuj euBioXmai [■lUIlllllllllllll > S86I ‘jaonn *AOu -ds B u g n o n u a q llSIf eugnuiBS/^ "l||||""'"'"""""“"“"""""""HW"»"""""""""""wn"'mi"”"y"""*"‘*"*"Hnmmn|||||l'' sisuauoSBJB eugnoguarf £ Bsoaads euiptoiiuai liiumiiiuniiii BUiud BugnuiBjt^ u 3SU3S rnm t unttDtfoo es BXBl pnbS3A3rj sgiqouv/i suojfig . Z - lo d a s i (0 < Z X ob e j B i 9|PP!V\I / ^ |J B 3 m g z - i < a6v N V I 0 H V O 1 Q , 1 0 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ■DCD O Q. C g Q. Ruget, 1980, 1983, Authors Copestake Boomer, 1991 ■D Exton & Gradstein, 1984 1986, 1987, Nicollin & Boutakioul, 1990 CD Johnson. 1984 (Mochras Present Ruget, 1986 in Bouta- (Morocco) study (worldwide) Grand Borehole, C/) Lusitanian kiout, 1990 (France, C/) Wales) Basin Banks Spain, Portugal) SUBZONES AALE Spccier unilculina NIAN PmmulH tenuliirluM 8 itnulsirlalu ■D Nudomria U nikuU m Lenilculma L tm im im d'om gny regularix dorblgnyl dorbignyi nibusia and Nitdosarlu pulchru Ekiyphocyihere blain'l " and CD Acnwyihere micheheni 3. U n tlc u lm 3" u n U c u im CD assemblage Cimrinu longuemari ?œn?... ptnntnsis mg M ■DCD gmdoM and L chichery O Dentaiina mgL,A.,P„F, Q. ulrkulalu C a Mimmmk m m m m O ciainraia sp sp 3 assemblage Lenticulina and "O Vaginulinal Lenticulina E. Inirepida O zone Citharina obonenis mg P obonetuis mg P, clathnita gr Lenlkuiina Lenticulina anigonënsIsmg'X CD L bochardi mgL, Q. aragonensis assemblage Suracenaria and Lenticulina L toarcense mg L zone sublaevis praeobonenis mg P Marginulina subiaevis prima picx. PLIENS Bolivina Zone wilh interruptaL sublaevis mg S Ogmoconcha rhumbieri Frondicularia Involutina Lenticulina convexa ■D Sarucenarh V-opsis terijuemi liassica subiaevis mg S. and CD BACHIAN rhumbleri tttbiaevis denticuiata L Insignis mg F. carinata C/) C/) Fig. 4.3 Bratca section biozonation compared to other microfauna-based zonal schemes. 34 The microfaunal evolutionary events and therefore the biozonation proposed for the Bratca section match closely the worldwide biozonation set forth by Copestake & Johnson, 1984, and to a lesser extent that of Exton & Gradstein, 1984 for the Lusitanian basin and the Grand Banks, mainly due to a delayed first occurrence of Lenticulina d'orbignyi in the latter. The same delayed first occurrence of this species is reported by Boutakiout, 1990 fix)m Morocco. The specimen of Bairdiacypris sp. illustrated by Exton & Gradstein (1984) is likely to belong to the species Bairdiacypris rectangularis Ainsworth, 1986, whose range in the Bratca section {B^ons-Thouarsense) is offset in respect to the Lusitanian basin (Tenuicostatum-Variabilis). The range of the species Lenticulina obonensis in the Bratca section is restricted to the ISerpentinus zone, the same as reported by Boutakiout (1990) in Morocco. Taphonomic observations The percentage of fragmented foraminifera specimens, missing either the last chambers or the proloculum, is shown in fig. 4.1 (“Fragmented specimens”)- Although some of this fragmentation might have occurred during sample preparation, the percentage is considered to generally reflect the energy level of the environment and therefore the degree to which the microfauna is affected by transport This percentage is low (9 - 21%) in the 'ISerpentinus zone and the lowermost part of the Bifrons zone (samples 188 - 185), higher (35 -61%) in the Tenuicostatum zone (sample 189) and the Bifrons and Thouarsense zones (samples 184-181 and 171), and very high (81-100%) in theVariabilis zone (samples 178 and 176). The microfauna of the Bratca section is affected to a variable extent by processes of partial dissolution and recrystallization. The quality of preservation, evaluated according to the intensity of the aforementioned processes, is shown in fig. 4.1 (“Preservation”). The best preservation occurs in samples 188 to 184, but even then recrystallization and neomorphism usually obscure features such as the radiate nature Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. of nodosariid apertures. Deformation of the foraminifers tests occurs rarely with specimens of Lenticulina, frequently withNodosana and Eoguttulina, and almost always withReinholdella. The preservation of the calcareous nannofossils found in sample 188 is moderate. Cementation of internal spaces in the microfauna from the Bratca section occurs virtually always; carbonate cement largely prevails, but samples 188-185 OSerpentinus zone and the lowermost part of the Bifrons zone) show a strong increase of the number of tests filled with pyrite. This trend closely matches that of the frequency of pyrite concretions in the residue and the dark gray to black color of the marls and shales corresponding to this interval. Almost all the specimens of the genus Reinholdella (occurring only in sample 188) have pyrite fillings. The valve/carapace ratios in ostracods display important variations among taxa. In most species almost all the valves are found as carapaces: Kinkelinella sennoisensis - 80% of the total number of valves found in the section, Ogmoconchella adenticulata - 86%, Trachycythere tubulosa - 98%, Liasina lanceolata - 99%, Bairdiacypris rectangularis - 100%. Two species have a significant number of disarticulated valves: Cytherella toarcensis - 56 % and Cytherella praetoarcensis- 44%. These percentages are generally constant in the stratigraphie succession - in fact the species that could be traced vertically belonged only to the first group, with very high percentages of carapaces. This result corresponds to the conclusions of Kilenyi (1971) and Michelsen (1973), that disarticulation is an individual characteristic of each species. Thin valves are preserved almost exclusively as carapaces, whereas thick valves can be also preserved when disarticulated. The fact that the percentages for the species whose valves can be preserved both ways could not be traced in the stratigraphical succession, as well as the generally small number of ostracods, prevented the valve/carapace index to be used in this study as a paleoenvironmental indicator. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 36 Paleoenvironments and sea-level variations The paleoenvironments of the Toarcian deposits of the Bratca section are reconstructed by interpretation of the lithology and the patterns of microfaunal abundance, diversity, heterogeneity, rate of faunal change, and fragmentation percentages. Data such as pyrite content of the residue and presence of other fossil groups, are also used. The lithology of the first 4 meters of the Bratca section (samples 189 through 185) is represented by an upward fining succession, from gray silty marls with occasional intercalated wackestones to finely laminated, bioturbation-free, pyrite-rich, dark gray and black shales (fig. 4.1). The distribution of foraminifera within this interval shows a marked pattern of abundance and diversity increase, with the notable exception of samples 187 and 186. Echinoderm fragments are abundant throughout this part of the section. Ammonites are present with the exception of the interval represented by samples 186 and 187. However, onychites (belemnoid arm hooks) are present in sample 186. The fragmented microfauna (as a percentage of the total number of specimens) is initially high, decreasing afterwards. These deposits, corresponding to the Tenuicostatum, ISerpentinus and lowermost part of the Bifrons ammonite zones, are therefore interpreted as representing a transgressive interval (fig. 4.1). An initially higher percentage of fragmented foraminifera (36% in sample 189) indicates the presence at this level of an environment with higher energy - and therefore shallower water depths - than in the next samples, which are characterized by low percentages of fragmented foraminifera (9-21% in samples 188 through 185). The deposits that belong to the ISerpentinus zone (samples 186 and 187) represent a kenoxic environment, corresponding to the Toarcian anoxic event, and therefore are equivalent to the organic-rich shales well known in western Europe at this stratigraphie level (the Jet-Rock in Great Britain, Posidonienschiefer in Germany Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 37 and Switzerland, Posidonia Shales in the North Sea area. Schistes Cartons in the Paris Basin). The deposition of these formations reflecting kenoxic conditions is linked to the major transgression that occurs during the lower Toarcian (Hallam & Bradshaw, 1979; Hallam, 1981; Copestake & Johnson, 1989). The residue of the samples 186 and 187 is characterized by a high content of pyrite in the form of concretions as well as GUings of internal cavities in foraminifera. The low abundance and diversity of foraminifera (and to a lesser extent of ostracods) in these two samples, strongly contrasting with those of adjacent ones, are explained as a result of low oxygen levels, a situation similar to that described by Johnson (1976) from the Falctferwn (= Serpentinus) zone deposits of the Mochras borehole in Wales. The lowest values of the aforementioned parameters are reached in sample 187, suggesting that the interval with the strongest dysaerobia is the lower part of the ISerpentinus zone. This fact is also supported by the virtual absence of echinoderm remains at this level. Although impoverished, the microfauna of this interval is made up of species that are found also in stratigraphically adjacent samples, reflecting probably only elimination of species unable to withstand lower oxygen levels. The foraminifera are represented in sample 187 by dwarf faunas (<250pm), a reaction to dysaerobia already described in the lower Toarcian of southwestern Germany (Riegraf, 1985) and Central Italy (Bartolini e t aL, 1992). The ostracods of samples 187 and 186 are represented by the species Liasina lanceolata and Trachycythere tubulosa, an assemblage similar to that dominated by L. lanceolata, reported in dysaerobic environments from the lower part of the Falctferum zone from the Mochras borehole, by Boomer & Whatley (1992). The transgression identiGed in the lower part of the Bratca section corresponds to the major sea-level rise that occurred during the early Toarcian, well-documented worldwide (Hallam, 1978, 1981, 1988; Haq er a/., 1988). Different authors have Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 38 proposed several stratigraphie levels as representing the peak of this sea-level rise. Copestake & Johnson (1989) consider it to correspond in Great Britain to the deposition of the regional black shale, at the base of the Falcÿerum (= Serpentinus) ammonite zone {Exarattun subzone), before "normal marine conditions became re established" in the upper part of the same zone {Falcÿèrttm subzone). Hallam (1981) and Haq et al. ( 1988) locate the peak of this sea-level rise in the lowermost part of the Bifrons zone. In the Bratca section, sample 188 is located above the level of major faunal renewal, but, although its residue contains high amounts of pyrite, according to its lithology and microfauna, this sample does not belong to the kenoxic facies represented by samples 186 and 187. The microfauna of sample 188 is characterized by high diversity and abundance, as well as the lowest percentage of foraminifer fragmentation. However, its heterogeneity is low, due to the fact that 75% of the foraminifer specimens belong to one species (Reinholdella macfadyeni). The examination of the rate of faunal change (the number of last local occurrences of foraminifera species deducted from the number of first local occurences for each sample) shows that sample 188 has the highest positive value (fig. 4.1), whereas beginning with sample 186 all the values are constantly negative or equal to zero. Because the predominance of new appearances seems to be generally related to transgressions, and that of extinctions is associated with regressions (Copestake & Johnson, 1989), this might represent an argument in favor of placing the maximum flooding surface of this sequence at this level. However, such an increase in extinctions, coinciding with a decrease in abundance and diversity might represent a facies change (Boomer, 1992), in this case to the kenoxic facies, which is not related to the end of the sea-level rise. Sample 188 is therefore interpreted as representing a deeper shelf environment (fig. 4.1 ), but the maximum flooding surface is considered to correspond in the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 39 Bratca section to the interval represented by sample 185. The latter, located at the boundary of the ’ISerpentinus and Bifrons zones, marks the re-establishment of normal marine conditions; its microfauna has the highest values for absolute abundance, diversity and heterogeneity (fig. 4.1). This peak in absolute abundance is likely to result at least in part from stratigraphie condensation, which is a decisive argument in favor of placing the maximum flooding surface at this level. The next 3.5 meters in the Bratca section - samples 184 through 181, most of the Bifrons and the lowermost part of the Variabilis anunonite zones - are represented by gray marls and intercalated wackestones. The foraminifera from the samples of this interval display a gradual but strong decline in abundance, diversity and heterogeneity, as well as significantly increased values of the percentage of fragmented specimens (35-61 %). After a peak in sample 184, the number of echinoderm remains is also reduced during the rest of this interval (fig. 4.1). This is interpreted as representing a decrease in water depth. Pyrite is present only occasionally in the residue or as fillings of inner chambers (sample 182). Siltstones, wackestones and packstones dominate the next 3.5 meters of the section (most of the Variabilis and the lower part of the Thouarsense zones). The indurated carbonate levels were sampled for thin sections, but they did not yield any microfauna. The rare marly levels (samples 176 and 178) yielded only a small number of foraminifera, belonging to only two species {Lenticulina muensteri and L acutiangulata); ostracods and calcareous nannoplankton are absent. The presence of the coarser clastic component as well as the very low abundance, diversity and heterogeneity of the microfauna, and very high percentages of foraminifera fragmentation (81-100%) indicate shallow waters, occasionally above wave base. Although the value of microfaunal parameters is less reliable in this interval, because of the very small number of specimens recovered, the presence of a shallow-water. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 40 high-energy environment at this level is confirmed by the sorting shown by the microfauna, consisting only of eroded, large-size tests. The lithology of the last two meters of the Bratca section is represented by marls and mudstones. The microfaunal content of sample 171 shows a return to higher values of abundance, diversity and heterogeneity of foraminifera, as well as lower percentages of foraminifera fragmentation (44%), comparable to those of samples 184 to 181. The deposits of this final interval of the section are thus interpreted as deposited in deeper waters, probably corresponding to the onset of a new sea-level rise. Agglutinated foraminifera are very rare throughout the Bratca section, the highest value of the agglutinated/calcareous foraminifera ratio being 0.1 (in sample 182). If the lack of clastic material during the deposition of the deeper-water deposits provides a good explanation during the early Toarcian, the absence of agglutinated-dominated foraminifera assemblages characteristic of marginal marine environments (Copestake & Johnson, 1989) is more difficult to explain for the middle Toarcian shallow-water deposits. Sample 188 was the only one among the three tested (189, 188 and 173) to yield calcareous nannofossils, supporting its interpretation as representing a deeper water environment. Q-mode cluster analysis using the relative abundance of the main components among foraminifera species (fig. 4.4) reveals only the existence of two biofacies units: unit I includes samples 183 through 171 and is interpreted as representing shallow water shelf environments, whereas unit H includes samples 189 through 184 (with the exception of sample 188) and is interpreted as representing deeper water shelf environments (fig. 4.5). Sample 188 represents an outlier because of the high dominance of species Reinholdella macfadyeni, but if this species would be removed sample 188 would be part of the cluster corresponding to unit II. According to its Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. aforementioned interpretation as corresponding to deeper water paleoenvironments, sample 188 is assigned to biofacies unit H (fig. 4.5). A more detailed subdivision of biofacies was achieved by Q-mode cluster analysis using as parameters the values of foraminifera diversity, heterogeneity and fragmentation percentages for each sample (fig. 4.6). The resulting biofacies subunits, listed below, are grouped in figure 4.5 according to their geologic interpretation. - La: samples with very low foraminifer diversity (2 species) and heterogeneity (0.7), and very high percentage of fragmented specimens (81-100%). This subunit, including samples 178 and 176, is interpreted as representing shallow water, inner neritic environments and high energy, probably above wave base. - Lb: samples with low foraminifera diversity (5-12 species) and heterogeneity (0.9-1.7), and high percentages of fragmented specimens (41-61 %). This subunit includes samples 171 and 181-183, and is interpreted as representing inner neritic environments. - Lc: samples with high values of foraminifera diversity (19-20 species) and heterogeneity (2.1-2.3), and moderate percentages of fragmented foraminifera (35- 36%). It includes samples 189 and 184, and is interpreted as corresponding to water depths between those of Lb on one hand, and H.a and II.b on the other (middle neritic environments). - II.a: samples with low values of foraminifera diversity (3-7 species) and heterogeneity (1-1.5), and very low percentages of fragmented foraminifera specimens (12-14%). It includes samples 187 and 186. This subunit corresponds to the black shales and is interpreted as an outer neritic environment, with deeper waters, low energy and reduced levels of oxygenation. - n.b: samples with very high values of diversity (20-23), and low percentages of fragmented foraminifera (9-21%). It includes samples 188 and 185. The Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 42 heterogeneity of sample 188 is lower than expected (1.2), due to the explosive development of species Reinholdella macfadyeni. However, if this species is not taken into account, the heterogeneity of the remaining assemblage would be very high (2.6). This group is interpreted as corresponding to outer neritic environments, with oxygen content within normal limits. These biofacies subunits are easily visualized in figure 4.7, a three-dimensional plot of the samples from Bratca section as a function of foraminifera heterogeneity, diversity, and percentage of fragmented specimens. Assigning a precise water depth to each biofacies is difficult and open to controversy; the landmarks were provided by the extremes: the high energy environment interpreted as above wave-base on one hand (I.a), and the black shales on the other. The latter are interpreted as deeper water environments corresponding to topographic lows on epicontinental sea-floors (Hallam & Bradshaw, 1979; Wignall, 1991; Wignall & Maynard, 1993), although no consensus has been yet reached in regard to their exact depth. According to the interpretation provided in the present study, the investigated deposits of the Bratca section belong to two third order sequences (figs. 4.1,4.8). The transgressive systems tract of the first sequence is recognised in the deposits corresponding to the Tenuicostatwn-'lSerpentinus zones; the maximum flooding surface is located at or slightly above the lower boundary of the Bifrons zone, and it is followed by the highstand systems tract corresponding to the rest of the Bifrons zone and part of the Variabilis zone. The sequence boundary is considered to be located at the contact between the more clastic deposits of the lowermost part of the Thouarsense zone, interpreted as representing the inner shelf, and the overlying marls and mudstones, interpreted as belonging to the transgressive systems tract of the second sequence. Since no evidence of subaerial exposure is present in the section, the boundary between the sequences might be conformable. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 43 100 90 80 70 60 50 40 30 20 10 0 L_ I _1_ _L_ _L_ I I _L_ J Fig. 4.4 Q-mode cluster analysis of the samples from Bratca section using the Euclidian distance to identify biofacies units. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 44 ENVIRONMENTSUNITS SAMPLES outer shelf, b 185/91 normal marine n 188/91 outer shelf, a 186/91 dysoxic 187/91 184/91 middle shelf c 189/91 171/91 inner shelf b I 181/91 182/91 183/91 inner shelf, a 176/91 within wave base 178/91 Fig. 4.5 Biofacies units and subunits in Bratca section, based both on Q-mode cluster analysis and geologic interpretation of the samples. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) C/) 8 100 90 80 70 60 50 40 30 20 10 0 ■D I I I I I I I I I I I outer nerilic, 185/91 , pormaj marjne 188/91 outerneritic" 186/91 *ic 187/91 ”184/91 3. .. 189/91 3 " inner-middle neritic ■\j -\i q -\ CD CD 181/91 ■D 182/91 O inner neriuc Q. 183/91 V/////////À C a inner neritic, 176/91 3o within wave base 1 7 3 /9 1 T 3 O CD Q. Fig. 4.6 Q-mode cluster analysis of the samples from Bratca section, using as parameters foraminifer diversity, heterogeneity and percentages of fragmented specimens in order to identify biofacies subunits. ■D CD C/) C/) ir. 46 135 1.5 2.5 •20 4 0 0outer shelf 60 0 outer shelf, dysoxic 0 middle shelf O inner shelf 0 inner shelf, high energy ^00 Fig. 4.7 Tridimensional plot of samples from the Bratca section as a function of foraminifer diversity, heterogeneity, and percentage of fragmented specimens. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) C/) Present study Hallam 1981.1988 Haq et al., 1988 Relative sea-level Eustatic sea-level Short term curve for Bratca section curve eustatic curve ■D8 High Low High Low ro 50m Om L eves- quei 3. 3 " CD ■DCD O Q. B ifrons C a m 3O "O O Tenui- CD c o s la lm Q. sequence boundary T R = transgressive systems tract H S = high-stand systems tract ■D _ maximum flooding surface, CD condensed section SM W - shelf-margin wedge (/) Fig. 4.8 Comparison of the relative sea-level curve for the Bratca section with Toarcian eustatic sea-level curves of other authors. 48 The resulting relative sea-Ievel variation curve for the deposits of the Bratca section (fig. 4.8) is very similar with the Toarcian eustatic sea-level curve of Hallam (1981, 1988) as well as with that proposed by Haqet al. (1988) for the Tenuicostatum - earlyBifrons interval. However, the latter authors suggest the existence of two sea-level rises during the late Bifrons-eaily Thouarsense interval, whereas only one is recognized during that time in the Bratca section as well as in the interpretation of Hallam (1981, 1988). Cubaynes et al. (1989) and Rey et al. (1994) have used the proportion of uncoiled and coiled forms of Lenticulina as a criterion in discriminating between system tracts. The ratio of the two types of forms also shows signiHcant variation in the Bratca material, but in this case the overall ratio cannot be considered to represent a reliable criterion, because this variation might simply reflect changing proportions between species of Lenticulina more or less prone of having uncoiled forms. Paleobathymetric model for microfauna distribution The bathymetric distribution of Jurassic microfaunas is still poorly known, due to the lack of modem analogs (Brouwer, 1969; Copestake & Johnson, 1989). In this study, R-mode cluster analysis of the foraminifer species that represent main components (>5% of the number of specimens) of the assemblages from the Bratca section, together with the averages of the percentages represented by each species in the samples of each biofacies subunit (fig. 4.9) are used to infer the paleoenvironmental affinities of foraminifera (fig. 4.10) and ostracod species. In conducting this analysis, the species Lenticulina muensteri and L acutiangulata have been grouped together as L ex gr. muensteri, reflecting both the fact that these species are closely related (Copestake & Johnson, 1989), and that their distribution in the Bratca section is very similar. This group of species is present in almost all the environments recognized in the section, with the exception of the deeper-water kenoxic environment (II.a). However, it strongly dominates shallow water Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 49 assemblages and strongly decreases in frequency as the water depth increases. The bathymetric distribution of the species Lenticulina bochardi in the Bratca section follows an opposite trend, being absent or very rare in shallow waters and abundant in deeper waters, including those with reduced levels of oxygenation. The comparison of these results with those of other authors is often difficult due to differences in the taxonomy used. Brouwer (1969), for instance, assigns the specimens of Lenticulina muensteri to L. bochardi, and those of L subalata, as well as probably L. chicheryi, to L varians. This author considers that the species Lenticulina gottingensis, as well as the genus Reinholdella, correspond to the deepest assemblages of the northwest-European epicontinental shelf; however, as stated by Jendryka-Fuglewicz (1975), the specimens illustrated by Brouwer as L. gottingensis belong in fact to a different, ornamented species of Lenticulina. The interpretation in the present study of Lenticulina ex gr. muensteri as paleobathymetrically wide-ranging but peaking in frequency in shallow waters differs substantially from that of Muller (1990), who describes it as representing the middle and outer shelf. Johnson (1976) assigns a inner to outer shelf range to L. muensteri, L. acutiangulata and L. subalata, also suggesting that the former reaches the greatest water depth. However, the interpretation of the present study is consistent with many reported occurrences of shallow-water assemblages dominated by L. muensteri in the Middle Jurassic of Great Britain, such as the assemblages studied by Morris & Coleman (1989), in the near-shore marine sediments of the Aalenian-Bajocian, and in the strongly regressive facies of the Aalenian. This species is also dominant in the shallow-water assemblages of the Lower Inferior Oolite (Bajocian) of England, described by Morris (1982). High abundance, low diversity assemblages dominated by L muensteri, were recovered by the author of the present study from the first marine sediments (interpreted as formed in near-shore environments) of the early Bajocian transgression in the Eastern Carpathians, Romania (unpublished data). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) C/) PERCENTAGE AVERAGES unit I unit II 100 90 80 70 60 50 40 30 20 10 la I.b I.C lf.a II,b L_ _1_ _l_ _1_ _L_ _L_ _L_ ■D8 100 74 33 0 8 L. gr. muensteri 0 6 4 0 3 L. subalata 0 0 11 8 6 L. chicheryi 0 0 8 0 6 L. sp, B 0 0 2 0 5 P. multicoslaia 0 0 2 6 7 L. obliqua 0 0 0 4 1 L, obonensis 3. 0 0 5 0 0 L. sp. D 3 " CD 0 0 4 0 0 L. aragoncnsis CD 0 0 4 0 0 V-ina listi ■D O 0 0 11 0 0 M. prima Q. C 0 2 6 17 2 L. varians a 0 0 0 18 1 L. pcnnensis o 3 0 2 0 39 15 L. bochardi T 3 O 0 0 0 38 0 R, macfadyeni CD Q. Fig. 4.9 R-mode cluster analysis of foraminifer species from Bratca section, using the Euclidian distance and ■D averages of the relative abundance of the species in the samples of each biofacies subunit. CD C/) C/) CD ■ D O Q. C g Q. ■D CD C/) C/) 8 Species L. ex gr. L. P. mulii- R. macfa L. L. * L. * L. varians L. sp.B L. obliqua vironments muensteri chicheryi coslaia dyeni bochardi obonensis pennensis outer shelf, dysoxic outer shelf middle shelf 3"3 Ï (D inner shelf (D T 3 Inner shelf, O Q. higjmjcrgy aC 3o T 3 O Fig. 4.10 Paleobathymetric distribution for selected foraminifer species from Bratca section. Shaded areas reflect (D Q. averages of relative abundance per biofacial subunit from fig. 11; (*) indicates species whose total number of specimens is <100 (L. pennensis - 44; L obonenis - 19). ■D CD C/) C/) 52 A consensus seems to exist concerning the interpretation of the genus Reinholdella as generally representing deep-water environments during the Liassic (Brouwer, 1969; Copestake & Johnson, 1989; Muller, 1990). In the Bratca section, the species Reinholdella macfadyeni occurs at the base of transgressive deposits probably corresponding to the Tenuicostatum-lSerpentinus boundary, as a localized flood (sample 188), a situation very similar to those reported by Ruget 1985, Copestake & Johnson 1989, Muller 1990. In the present study, this species is associated with biofacies II.a, representing outer neritic environments with oxygen levels within normal limits. The thin stratigraphie interval characterized by the extreme abundance of this taxon and located at the base of an transgressive systems tract, represents a typical example of an epibole, as dehned by Brett (1995). Early development of pyrite molds has certainly played an important part in the preservation of the aragonitic tests of this species. However, the pyrite-rich stratigraphie interval has a much larger extent than the distribution of Reinholdella macfadyeni. This indicates that the epibole may be classified as both taphonomic and écologie. Although the small number of specimens recovered in the case of the species Lenticulina obonensis and L. pennensis makes interpretations less reliable, it is worth noting that in the Bratca section these species are main components of the kenoxic assemblage. Boutakiout (1990) records the former species as being very abundant in the restricted environments of the Serpentinus zone of Morocco. A similar analysis is less relevant in the case of the ostracods from the Bratca section, again because of their lesser numbers and spottier record; it can be inferred, however, that assemblages made up of Liasina lanceolata, Trachycythere tubulosa, and Bairdiacypris triangularis correspond to deeper waters, the former two being the only ones to withstand the low oxygen levels of the deep-water kenoxic environment. Assemblages including Bairdiacypris rectangularis, Cytherella toarcensis. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Ektyphocythere debilis, and Kinkelinella sermoisensis are found at paleodepths corresponding to the middle and inner neritic. Paleobiogeography The ammonite assemblages identified in the Bihor Autochtonous of the Northern Apuseni Mountains are described by Patrulius & Popa (1971) as being of "pure NW- European type, without Phylloceratids”. The microfaunal evidence of section Bratca strongly supports this conclusion. A number of 38 out of the 47 identified foraminifer species, and 13 out of 19 ostracod species are commonly found in Toarcian deposits of Western and Central Europe. The Bratca Toarcian foraminifer assemblages, strongly dominated by nodosariids, with an occasional flood of ceratobuliminids, and very rare simple agglutinated forms, belong to the Boreal realm - group A1 and A3 of Gordon (1970), corresponding to the Jurassic shells with prevailing terrigenous sedimentation. Organic-rich black shales formed during the Toarcian Anoxic Event have also been described from the south Tethyan margin (Bartolini et a i, 1992). However, the taxonomic composition of the associated foraminifer assemblages, dominated by the Lingulina tenera group, is different from that of the corresponding deposits from the Apuseni Mountains, where the aforementioned group is completely absent. Within the more refined latitudinal and bathymetric zonation of Jurassic foraminifer assemblages of Basov (1991), the Bratca assemblages belong to the nodosariid- epistominid type, interpreted as corresponding to shelf deposits in subtropical and perhaps temperate areas, and to deeper waters in tropical areas when associated to planktonic forms. Even in the intervals of prevailing carbonate sedimentation, Pseudocyclammina liassica is the only agglutinated foraminifer with complex internal structuress reported from the Liassic deposits of the Northern Apuseni Mountains (Popa et al., 1982). The lack of any other such forms and especially of those belonging to the genus Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54 Orbitopsella, characteristic of the south Neo-Tethysian margin (Bassoullet et al., 1985), as well as the strong affinities with nortwestem Europe shown by the microfauna of the Bratca section, indicate that during the Liassic the Northern Apuseni Mountains area was part of the north Tethysian shelf. Systematics The generic systematics of foraminifers used in this study is that of Loeblich & Tappan (1988), whereas the classification for the ostracods is based on that set forth by Hazel (1983). In dealing with the high intraspecific variability of nodosariids, the term morphogenus, as used by Ruget (1985) has been adopted in this study. The matter of the most appropriate term to be used in this circumstance has been discussed in detail by Ruget (1985). Nodosariid genera such as Lenticulina, Astacolus, Planularia, Marginulinopsis, Falsopalmula, Saracenella and Vaginulinopsis have been defined on material younger than Jurassic. The criteria used in order to define these taxa are chamber arrangement and general test shape. A general consensus has been reached concerning the value of the aforementioned features for foraminiferal classification at the genus level, as well as concerning the use of external ornamentation as the main criterion for species classification within this group (Loeblich & Tappan, 1988). However, the detailed inventory of Jurassic (and especially Lower Jurassic) nodosariids showed the coexistence of forms belonging to the same species, according to their complex and very characteristic external ornamentation, but to different genera, according to the chamber arrangement and general test shape (Ruget, 1985). This phenomenon is present to some degree in almost all the representatives of the subfamily Lenticulininae recovered in the present study, but the most complete spectrum of “genera” was identified in the case of the species Lenticulina chicheryi and L. bochardi. The fact that these "forms" are not stages of individual development or the consequence of alternating generations needs to be emphasized; they represent adult morphologies. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 3 existing together or progressively replacing each other in time, hence being of stratigraphie interest (Ruget, 1985). Since no other foraminifer group provides reasons to doubt the validity of the criteria currently used for foraminifer classification and recent nodosariids species do not display this “shif^’ in morphology from one genus to another, a special term needs to be used in dealing with this phenomenon affecting Jurassic nodosariids. The first author to approach this issue was Bartenstein (1948), who grouped all the forms involved into a comprehensive genus (Lenticulina) and considered all different morphologies as subgenera. Bykova (1960) also kept one genus in a large sense and mentioned in square brackets the morphological stage reached within the species. Magniez (1976) used the same way of writing but preferred the genus Cristellaria to Lenticulina. This approach has been used less frequently in the last two decades because it implies the existence of intraspecific subgenera. It is not acceptable to consider the different “forms” of the species involved as simple morphotypes. Simple morphotypes existing within a species are not related to those of other species. In the case of the Jurassic nodosariids, the forms existing within all concerned species develop along the same morphological lines, corresponding to genera existing among more recent representatives of this group. A widely used approach, especially in studies focusing on biostratigraphy and not concerned with taxonomy, such as Copestake & Johnson (1989), consists in using as a generic name for all the forms belonging to a species the “genus” that prevails among those forms. For instance in the case of the middle and upper Jurassic species Planulina tricarinella, all forms are assigned by the aforementioned authors to the genus Planularia, although a fraction of the forms display chevron-shaped last chambers, corresponding to the morphology of the genus Falsopalmula. Obviously, this approach amounts to simply ignoring the problem; it is used for practical reasons and lacks scientific rigor. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 56 Ruget (1985) also grouped all the forms affected by this “shifting” between nodosariid genera in a comprehensive genus {Lenticulina) and coined the term morphogenus to describe the similar morphologies existing within each species. Apparently, this term has the drawback of still including the word "genus", obviously undesirable for describing intraspeciOc variation. However, this simply reflects the nature of the problem - Jurassic nodosariid species developing morphotypes corresponding to genera as defined on Cenozoic material - a problem that does not appear to have a standard solution within the framework of Linnéan classification. The term morphogenus is more relevant than simply "morphotype", which does not address the phyletic relationships of similar types of "forms" found in different species. Lenticulina, Astacolus, Planularia, Marginulinopsis, Falsopalmula, Saracenella and Vaginulinopsis are therefore considered in the present study as morphogenera of the genus Lenticulina. Included in this chapter are only the taxa that are either controversial or left here in open taxonomy. Synonymies are limited to the most important works. Specimens are deposited in the Howe collection. Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana. Part 1. Foraminifera Order Foraminiferida Eichwald, 1830 Suborder Textulariina Delage & Herouard, 1896 Superfamily Trochamminacea Schwager, 1877 Family Trochamminidae Schwager, 1877 Subfamily Trochammininae Schwager, 1877 Genus Trochammina Parker & Jones, 1859 Trochammina sp. A (PI- 1, fig. 6) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 57 Material: 9 specimens Horizon: Bifrons zone. Description: test with low trochospirai coiling, strongly compressed laterally, 6-7 chambers in last whorl. Suborder Lagenina Delage & Herouard, 1896 Superfamily Robnloidacea Reiss, 1863 Family Ichthyolariidae Loeblich & Tappan, 1986 Genus Ichthyolaria Wedekind, 1937 Ichtyolaria sulcata (Bomemann, 1854) (PI. 1, fig. 8) 1854 Frondicularia sulcata Bomemaim: 37, pl.3, fig. 22a-c. 1937 Frondicularia sulcata Bartenstein & Brand: 158, pLlA, fig. 12; pl.2A, fig. 19, pl.2B, fig. 20, pl.4, fig. 50. 1957 Frondicularia sulcata Barnard: 174-179, pl.l, figs B, C, E, F, pi.2, figs 1- 7, 9, 15, 16, 17. pars 1969 Frondicularia bicostata Brouwer: 35, pl.5, figs 9, 12, 22, 23. 1979 Frondicularia bicostata sulcata Exton: 34, pl.2, fig. 12. 1985 Ichtyolaria sulcata Ruget: 95, pl.3, figs 2-4,6-11, pl.4, figs 4, 10, 11, pi. 14, figs 1-8, 10, 11, pi. 15, figs 7-10, pi. 16, figs 1-13, pi. 17, figs 1-12, pi. 18, figs 1-7, 10, pl.27, fig. 11, pl.28., figs 1-3, 5-12, 16, 17, 19, pl.29, figs 2, 9, 13, pl.39, fig. 5, pl.47, figs 1-3, 5, 6, 8, 9, 12-15. pars 1989. Frondicularia terquemi sulcata Copestake & Johnson: 174, pl.6.2.3, figs 6, 8. Description: test compressed, with 12 fine parallel longitudinal ribs, 6 to 8 chambers with flat sutures and no median sulcus. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 58 Remarks: The speciesIchthyolaria sulcata is interpreted in this study according to Ruget 1985: test strongly compressed, with 9 to 16 parallel ribs and without median sulcus. Some of the more compressed specimens figured by Copestake & Johnson 1989 as Frondicularia terquemi sulcata are very similar to the Bratca material. The external ornamentation of the Bratca specimens is identical with that of /. muelensis, but they differ in having a less narrow and elongated test, a larger angle between the sutures and the longitudinal axis, and especially a lower number of chambers - 12 to 15 in /. muelensis. Superfamily Nodosariacea Ehrenberg, 1838 Family VaginuUnidae Reuss, 1860 Subfamily Lenticulininae Chapman, Parr & Collins, 1934 Genus Lenticulina Lamarck, 1804 Lenticulina muensteri (Roemer, 1839) mg Lenticulina (PI. 1, fig. 19) 1839 Robulina munsteri Roemen 48, pl.20, fig. 29. 1975 Lenticulina muensteri Jendryka-Fuglewicz: 149, pl.8,9,10; pl.l 1, figs 1-6, pi. 19, pl.20, figs 1,2. 1989 Lenticulina muensteri muensteri Copestake & Johnson: 178, pi.6.2.4, fig. 2 . Description: test large, smooth, strongly biconvex, with angular periphery, flush sutures and smooth umbilical area. Remarks: this species is very close to L acutiangulata, and L subalata , the latter two being regarded by Copestake & Johnson (1989) as subspecies of L muensteri. L muensteri differs from the other forms by lacking keeled margins, raised sutures or thickened umbilical bosses. Some authors (Jendryka-Fuglewicz, 1975; Boutakiout, 1990), distinguish between L gottingensis (a stratigraphically Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 59 older form) and L. muensteri, mainly due to a flatter test and lack of a true umbilical boss in the former. Brouwer (1969) assigns the forms belonging to L muensteri to L bochardi; the two represent clearly distinct species according to most authors and the present study. Uncoiled forms of the species L. muensteri are described in the literature, but only forms belonging to the morphogenus Lenticulina were found in the Bratca section. Lenticulina subalata (Reuss, 1854) mg Lenticulina, Marginulinopsis (PI. 1, fig. 20) 1854 Cristellaria subalata Reuss: 68, pl.25, fig. 13. 1978 Lenticulina (Lenticulina) subalata Karampelas: 60, pl.2, fig. 17 1989 Lenticulina subalata Ebli: 72, pl.3, fig. 3. 1989 Lenticulina subalata Morris & Coleman: 226, pl.6.3.8, fig. 13. Description: test biconvex, with strongly raised sutures and umbilical boss, often keeled. Remarks: this species is close to L muensteri and L. acutiangulata, but differs from them in having raised sutures. Among Toarcian forms, some authors (Exton 1979, Boutakiout 1990) differenciate the species L. toarcense, similar to L subalata, based on less salient sutures and umbilical boss, as well as a lesser number of chambers in the last whorl (8 to 12) in the former. The specimens investigated in the present study have 9 to 13 chambers in the last whorl; the morphogenus Marginulinopsis is extremely rare. Lenticulina polygonata (Franke, 1936) mg Lenticulina (PI. 2, fig. 2) 1936 Cristellaria (Lenticulina) polygonata Franke: 118, pi. 12, figs la,b, 2a,b. 1968 Lenticulina muensteri polygonata Welzel: 42, pl.2, fig. 38. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 60 1975 Lenticulina po/ygonara Jendryka-Fuglewicz: 136, pl.2, figs 7, 8. 1985 Lenticulina polygonata mg Lenticulina Ruget: 64, pl.32, figs 1,2. 1978 Lenticulina (Lenticulina) polygonata Karampelas: 60, pl.2, fig. 12. Description: test small, moderately biconvex, with polygonal outline and sutures slightly raised to fiush. Remarks: this species, as described in the literature, might group specimens actually belonging to different taxa, since the most important feature of this species - the polygonal outline, obvious especially in the last few chambers, is not unique (it also appears, for instance, in some specimens of L. bochardi). Two morphological groups are represented in the Bratca material, one appearing to be related to L. muensteri, but poor preservation and the small number of specimens limited the investigation. Lenticulina iocAardi (Terquem, 1863) mg Lenticulina, Marginulinopsis (PI. 2, figs 3, 4) 1863 Cristellaria bochardi Terqxiem: 209, pi. 10, fig. 3 a,b,c. 1960 Lenticulina bochardi Bizon: 5, pl.l, fig. 4a,b, pl.4, fig. 15. 1964 Lenticulina bochardi Barbieri: 756, pl.57, fig. 10 a,b. 1990 Lenticulina bochardi mg Lenticulina Boutakiout: 115, fig. 30, pl.7, fig. 10. Description: test with slightly raised umbilical boss and sutures, especially in the first third of the last whorl, with keeled periphery, except for the last third of the whorl; the suture of the last chamber - and of the additional chambers in forms with an uncoiled part - slightly depressed, especially on the umbilical side, giving the last chamber an inflated appearance. In some specimens the last chambers tend to have an polygonal outline. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 61 Remarks: This species is similar to theL. muensteri group, especially to L subalata , due to the raised sutures, but differs in the distinctive shape of the last chamber. Lenticulina cAfcAery: Payard, 1947 mg Lenticulina, Astacolus, Planularia, Marginulinopsis, Falsopalmula (PI. 2, figs 5-9) 1947 Lenticulina chicheryi Payard: 87, pl.7, fig. 7. pars 1969. Lenticulina varians Brouwer: 37, pl.7, figs 10-17. 1979 Palmula chicheryi Exton: 42, pl.6, figs 3,4. 1985 Spectre Lenticulina chicheryi Ruget: 81, pl.41, figs 1-14. 1990 Lenticulina chicheryi mg Lenticulina, Astacolus, Marginulinopsis, Planularia, Falsopalmula Boutakiout: 118, fig. 30, pl.8, figs 14-18. Description: test with 7 to 9 biconvex, triangular-shaped chambers in the initial coiled part, with sutures marked by strong, curved ribs. In specimens belonging to theFalsopalmula morphotype the uncoiled part consists of flattened chevron-shaped chambers, showing equal overlap on ventral and dorsal margins. Remarks: Forms belonging to this species were assigned by some authors (Bartenstein & Brand, 1937; Barnard, 1950; Brouwer, 1969) to the species L variabilis. However, Brouwer (1969) notes that the true L. varians has flush sutures, whereas this form has elevated sutures. Exton (1979) has illustrated specimens belonging to the morphogenera Lenticulina and Falsopalmula and has assigned them to the species Palmula chicheryi. Lenticulina varians (Bomemann, 1854) mg Lenticulina (PI. 2, fig. 10) 1854 Cristellaria varians Bomemann: 41, pl.4, figs 32—34. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 62 1968 Lenticulina varians varians Welzel: 43, pl.2, figs 32,33. pars 1969 Lenticulina varians Brouwer: 37, pl.7, figs 10, 11. 1975 Lenticulina varians Jendryka-Fuglewicz: 137, plJZ, figs 1,2. 1981 Lenticulina varians Mira & Martinez-Gallego: 331, pl.2, fig. 12. 1989 Lenticulina varians plexus Copestake & Johnson: 176, pl.6.2.4, fig. 3. Description: test smooth, compressed, with tendency to uncoiling, sutures fiush or slightly raised, periphery often keeled. Remarks: only forms lacking strongly elevated sutural ribs were assigned to this species. Lenticulina cf. L. pennensis Cubaynes & Ruget, 1983 mg Marginulinopsis (PI. 2, fig. 13) 1983 Lenticulina (Marginulinopsis)pennensis Cubaynes & Ruget: 376, pl.l, figs 1-13. 1985 Lenticulina pennensis mg Marginulinopsis Ruget: 84, pl.44, figs 9, 12, 13. 1990 Lenticulina pennensis mg Marginulinopsis Boutakiout: 119, fig. 30, pl.9, fig. 4. Description: test biconvex, thickened in the central part of the chambers and wedged on the ventral and dorsal sides, with 8 to 10 chambers; sutures flush, slightly depressed in the last one or two chambers. Remarks: although all the specimens from Bratca belong to the morphogenus Marginulinopsis and have 9 to 10 chambers, the uncoiled part is small in respect to the coiled one, never reaching the lenght seen in specimens illustrated by other authors. The difference in thickness between the central part of the coil and the margins is not very large, resulting in a less obvious keel. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 63 Lenticulina obliqua ÇÏCTqn&m, 1864) mg Astacolus, Planularia, Falsopalmula (PL 2, figs 16-18) 1864 Flabellina obliqua Terquem: 217, pi.IO, fîg. 15. 1937 Flabellina obliqua Bartenstein & Brand: 168, pl.5, fig. 64, pl.5, fîg. 51. 1964 Falsopalmula obliqua Barbieri: 777, pl.60. fig. 17. 1985 Lenticulina obliqua mg Falsopalmula Ruget: 74, pl.32, figs 5-6. 1989 Palmula obliqua Morris & Coleman: 224, pl.6.3.8, fig. 2. Description: test highly compressed with proloculus located on the ventral margin, sutures marked by fine ribs; chevron-shaped chambers in specimens of the morphogenus Falsopalmula do not extend to the coiled part. Remarks: differs from L deslongchampsi by the assymetry resulting from the position of the proloculus and by the flabelline portion, which does not cover the coiled one. Lenticulina aragonensis Ruget, 1982 mg Saracenella (PI. 3, figs 3, 4) 1982 Lenticulina [Saracenaria Saracenella] aragonenis Ruget: 70, pl.5, figs 16, 18-22, pl.6, figs 6, 11, 13-17, 19-21. 1985 Lenticulina aragonensis mg Saracenella Ruget: 84, pl.46, figs 5-7,9, 10. 1989 Saracenella aragonensis Copestake & Johnson: 184, pl.6.2.6., figs 2, 3. Remarks: the specimens from Bratca correspond to the low end of elongation variability range of this species, as illustated by different authors, and none has an inflated or spherical final chamber. However, the triangular section of the test, with swollen margins and concave sides allows them to be assigned to this species. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 64 Lenticulina sp. nov. Ruget, 1985 mg Planularia (PI. 3. figs 6, 7) 1985 Lenticulina mg Planularia Ruget: 57, pl.32, fig. 9,15, pl.33, figs 12, 13, 15, non pl.32, fig. 8, non pl.33, fig. 14, non pl. 10, figs 4, 6, non pl.Il, figs 2, 7. Description: test with keeled periphery and 5 longitudinal ribs, parallel to the dorsal margin but falling at a right angle on the coiled portion. The ribs do not join and do not reach the lower margin of the coiled portion. Lenticulina sp. A mg P la n u la ria (PI. 3, figs 8, 9) Material: 5 specimens Horizon: Bifrons zone. Description: test smooth, laterally compressed, with a small coiled part and a larger uncoiled part comprising 5-6 chambers; posterior margin straight to slightly curved, sutures slightly depressed. Lenticulina sp. B mg Lenticulina^ Astacolus, Marginulinopsis (PI. 3, figs 10, 11) Material: 167 specimens Horizon: Tenuicostatum -Bifrons zones. Description: test smooth, thickened in the central part of the coiled portion, sutures flush in the coiled portion comprising 9-10 chambers, and slightly depressed in the uncoiled portion; margins rounded. Lenticulina sp. C mg Lenticulina, Marginulinopsis (PI. 3, fig. 12) Material: 3 specimens Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 65 Horizon: Bifrons zone Description: test large, smooth, with 9-10 chambers in the last whorl, polygonal outline, posterior margin strongly curved, and angular margins. Lenticulina sp. D mg Marginulinopsis (PI- 3, figs 13, 15) Material: 21 specimens Horizon: Tenuicostatum zone Description: test smooth, ellipsoidal to subcircular in cross section, with sutures flush to slightly depressed especially in the last chamber; posterior margin slightly curved to straight Marginulina sp. A (PI. 3, figs 16, 17) Material: 3 specimens Horizon: Bifrons zone. Description: test rectilinear, smooth, ellipsoidal in cross-section, consisting of 7 chambers with depressed sutures; posterior margin straight and anterior margin lobate. Subfamily Vaginulininae Reuss, 1860 Genus C itharina d’Orbigny, 1839 Citharina clathrata (Terquem, 1863) (PI. 3, fig. 19) 1863 Marginulina longuemari var. c/a/Ara/a Terquem: 192, pl.8, figs 16, 19a,b. 1987 Citharina clathrata Mira: 153, figs 2, 1-17, pi. 1, figs 3-6. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 66 1989 Vaginulina/Citharina clathrata Copestake & Johnson: 184, pl.6.2.6, figs 4- 5. 1989 Citharina clathrata Morris & Coleman: 210, pl.63.2, figs 5,6. 1990 Citharina clathrata Boutakiout: 146, fig. 33, pi. 14, figs 4,5. Remarks: the ornamentation of this species consists of coarse longitudinal ribs, parallel to the dorsal margin, and evenly distributed over the entire surface of the flanks. Citharina longuemari (Terquem, 1863) (PI. 3, fig. 20) 1863 Marginulina tongueman Terquem: 192. 1985 Citharina longuemari Ruget: 80, pl.45, figs 4, 10, pl.46, figs 1,4, 8. 1990 Citharina longuemari Boutakiout: 144, fig. 33, pi. 13, figs 17-22. Remarks: this species is close to C. clathrata, but differs from it in having the longitudinal ribs grouped in a bundle, resulting in flat areas along the margins of the test. Indeterminate foraminifer A (PI. 4, fig. 4) Material: I specimen Horizon: top oP.Serpentinus zone. Description: test calcareous, biserial, smooth, with sutures slightly depressed, elipsoidal section and rounded periphery. P art 2. O stracods Class Ostracoda Latreille, 1806 Order Podocopida Muller, 1894 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 67 Suborder Platycopina Muller, 1894 Superfamily Cytherellacea Sars, 1866 Family Cytherellidae Sars, 1866 Subfamily Cytherellidae Sars, 1866 Genus C ytherella Jones, 1849 Cytherella cf. C, praetoarcensis Boomer, 1991 (PI-4, fig. 5) 1991 Cytherella praetoarcensis Boomer: 206, pl.2, figs 4,5,9. 1992 Cytherella praetoarcensis Boomer 50, pl.l, fig. 8 Remarks: this species is characterized by its distinctly steeply sloping postero- ventral margin, obvious in the Bratca specimens. However, the latter tend to be more elongated and to have a slightly concave postero-dorsal margin, compared to the slightly convex postero-dorsal margin of the specimens illustrated by Boomer (1991, 1992). Genus Cytherelloidea Alexander, 1929 Cytherelloidea sp. A (PI. 4, fig. 7) Material: 5 carapaces Horizon: Bifrons-Thouarsense. Description: Carapace with subrectangular outline, valve surface smooth, narrow peripheral rib developped only along the posterior margin. Suborder Podocopina Sars, 1888 Superfamily Bairdiacea Sars, 1888 Family Bairdiidae Sars, 1888 Subfamily Bairdiinae Sars, 1888 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 68 Genus Bairdiacypris Bradfïeld, 1935 Bairdiacypris rectangularis Ainsworth, 1986 (PI. 4, figs 9, 10) 1975 Bairdiacypris sp. Bate & Coleman: 5, pl.9, fig. 13. 1979 Bairdiacypris sp. Exton: 55, pl.l 1, fig. 11. 1986 Bairdiacypris rectangularis Ainsworth: 295, pl.3, figs 1,2,7. Remarks: This species is very close to Bairdiacypris dorisae (Knitter, 1983), but the specimens from Bratca are assigned to B. rectangularis due to their less arched dorsal margin and less acuminate posterior. Superfamily Cypridacea Baird, 1845 Family Candonidae Kaufmann, 1900 Subfamily Paracypridinae Sars, 1823 Genus Paracypris Sars, 1866 P aracypris sp. A (PI. 4, fig. 11) Material: 2 carapaces Horizon: Tenuicostatum -ISerpentinus zones. Description: Carapace of medium size, elongate subtriangular. Anterior margin bluntly rounded, posterior margin acuminate, and ventral margin concave. Valve surface smooth. P aracypris sp. B (PI. 4, fig. 12) Material: 1 carapace Horizon: Bifrons zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 69 Remarks; Differs from Paracypris sp. A in being smaller, less elongate and having a straight ventral margin. P aracypris sp. C (PI- 4. fig. 13) Material: 1 carapace Horizon: Thouarsense zone. Description: Carapace of medium size, elongated subtriangular. Anterior margin broadly rounded, posterior margin fractured. Ventral margin slightly concave. Faracyprisl sp. D (PI. 4, fig. 14) Material: 4 carapaces, 1 valve Horizon: Bifrons zone. Description: carapace small, with posterior margin moderately acuminate, extremity situated at one third of the height from the ventral margin. Ventral margin straight. Anterior margin broadly rounded, extremity located above the middle of the height. Valve surface smooth. Internal features not observed. Indeterminate Genus 1 sp. A (PI. 5, figs 11, 12) Material: 6 carapaces Horizon: Bifrons zone. Description: Carapace of medium size, elongate subtriangular, more or less deformed in all specimens. Dorsal margin a low arch, posterior margin narrowly rounded. Ventral margin concave, especially in the anterior third. Valve surface smooth. Internal features not observed. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 5. BAJOCIAN (MIDDLE JURASSIC) FORAMINIFERA AND OSTRACODS FROM STRUNGULITA, EASTERN CARPATHIANS, ROMANIA Lithology The Strungulita section is located on the western flanks of the Bucegi Mountains, in the southern section (Leaota-Bucegi-Piatra Mare) of the Central Carpathian Unit of the Eastern Carpathians (fig. 13). The Middle Jurassic deposits of this section begin with 2.5 meters of quartzitic conglomerates and sandstones which overltq) Proterozoic crystalline schists. At the top of this interval thin lenses of coal are present. The first marine deposits are represented by 0.3 meters of shale and marl, from which Neague t aL (1983) recovered an abundant bivalve fauna (fig. 5.1). Overlaying these shales are 3 meters of sandstones and marls with a fauna of bivalves, gastropods, and serpulids. The next 3.5 meters consist of gray shales that yield a rich fauna of bivalves, echinoderms, and solitary corals. The samples investigated in the present study were collected from this interval (fig. 5.1). The shales are overlain by 10 meters of dark gray wackestone with thin intercalated marl, part of which cannot be directly observed, followed by a 1 meter thick fossiliferous packstone with very abundant brachiopods. The next 50 meters are represented by the Tataru Peak Sandstone (Neagu et aL, 1983), consisting of yellow quartzitic sandstone and packstone with thin intercalated levels of oolitic packstone and microconglomerate. The Tataru Peak Sandstone is followed by a brown mudstone with limonitic levels at the top, which have yielded a rich ammonite fauna (Patrulius, 1969; Neagu et aL, 1983). The section ends with gray marls and polycolor jasper containing radiolarians and rhyncholites (cephalopod jaws), and over 30 m of nodular limestones with ammonites, corals and brachiopods (Acanthicum beds), followed by white massive limestones of Stramberg type, 200 meters thick. 70 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 71 systems tracts Macrofmmar brown limestone with Uacrocephalita macrocephalus Hi B limonitic levels PhyUoctras kudemauchi yellow calcareous sandstone (Tataru Peak Sandstone) packstone brachiopods % 1 m u < I u dark gray wackestones tsognomon isoptomoides X fl with intercalated marls L o p h a sf. o P inasp. 1-3 < P5 u Pholadomya murchinsoni 8 Pleuromya anifomis MFS gray shales 4 Pburomya sp. D M boarctt sp. Mondivaltia sp. H 1 Pholadomxa mirchinsoiu < sandstones and Pleuromya uniforma H marls P ecun demisus iL) / Mytilus suprajurerais mart U .petaius ^^d.lynceus conglomerate and sandstone with coal lenses sequence boundary PRECAM- transgressive systems tract crystalline schists BRIAN high-stand systems tract ■ maximum flooding surfocc Fig. 5.1 Lithology and macrofauna of the Strungulita section. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 12 Biostratigraphy The first ammonite-bearing level in the Strungulita section is the limonitic facies at the top of the Tataru Peak Sandstone, which yielded an assemblage indicative of the Bathonian - early Callovian (Patrulius, 1969; Neagu et aL, 1983). Also based on ammonites, the age of the interval represented by the polycolor jaspers, Acanthicum Beds, and white massive limestones is Oxfordian - Tithonian (Mutihac & lonesi, 1974). In the Strungulita section, the clastic deposits older than and including the Tataru Peak Sandstone are considered to represent the Bajocian (Mutihac & lonesi, 1974), based on the bivalve and brachiopod assemblages. Neagu et al. (1983), assign a middle-late Bajocian age to the gray shale interval, based on the epistominid and Ophthalmidium dominated microfaunal assemblage, deemed to be typical for this time interval in northern Europe. The microfaunal assemblages identified in the present investigation are listed in Appendix B. The most important component of the foraminifer assemblages from Strungulita is represented by species of the genus Epistomina (£. regularis, E. coronata, E. nuda), followed by nodosariids and Ophthalmidium infraoolithica. A late Bajocian age is indicated for this assemblage by the range of the most important species as well as by the occurrence of assemblages with similar composition in areas adjacent to Romania’s territory. Assemblages dominated by epistominids, nodosariids, and ophthalmiids are reported from the upper Bajocian and lower Bathonian (Parkinsoni and Zigzag ammonite zones) of extra-Carpathian Poland (Bielecka et al., 1988). The speciesEpistomina regularis and E. nuda first occur in extra-Carpathian Poland beginning with the upper Bajocian, whereas E. coronata first occurs in the same area during the uppermost Bajocian (Pazdro, 1969). The species Ophthalmidium infraoolithica is reported by Grigelis et al. (1991) as occurring in Ukraine beginning with the upper Bajocian {Garantiana ammonite zone). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 73 Paleoenvironments The paleoenvironmental interpretation of the Bajocian deposits from Strungulita section, using both lithologie and faunal data was discussed by Neagu et al. (1983). The clastic deposits that overlap the crystalline schists, beginning with the conglomerates and sandstones with coal lenses, and ending with the gray shales, represent a typical transgressive sequence. The gray shale level is interpreted by the aforementioned authors as representing the most open marine facies. The low energy of the environment is shown by the rich population of the bivalve Pholadomya murchinsoni, with most of the individuals preserved in their normal living position. The relatively abundant presence of the solitary coral Montlivaltia sesilis points to normal salinity, warm waters. The very low levels of the coarser clastic component indicate remoteness from the shore. The lack of planktonic foraminifera and the relatively low diversity of the assemblage allowed Neagu et al. (1983) to interpret the gray shales as representing an outer inner shelf or even middle shelf environment. The Tataru Peak Sandstone is considered by Neagu et al. (1983) to mark a return to a facies with a strong clastic input from the continent. The overlying brown mudstone including the ammonite-bearing limonitic facies corresponds to deposition in deeper waters. The contact between the coarse elastics of the Tatam Peak Sandstone and the brown mudstone was erroneously interpreted by Neagu et al. (1983) as a hardground, and actually represents a surface of subaerial exposure The rest of the Jurassic deposits of the Strungulita section are deposited in a carbonate neritic facies. The foraminifer assemblage of the first three samples (1,4, 8) investigated in the present study is dominated by epistominids, which represent 79-98% of the total number of specimens (fig. 5.2). Among the species of this group, Epistomina nuda represents only a small proportion (1-9% of the total foraminifera), the rest belonging Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 74 to the species E. regularis and E. coronata. The latter represents around 5% of the total foraminifera, but due to poor preservation it was not always possible to distinguish it from E. regularis and therefore to calculate an accurate proportion. The last sample (11) shows a major change in foraminifer species distribution, represented by the complete absence of E. regularis and E. coronata and the high frequency of Lenticulina ex. gr. muensteri and £. nuda. This important change does not correspond to a shift in lithology, but seems to be reflected in the ostracod assemblage by a sudden increase in the frequency of cytherellids. The present study, using microfaunal parameter measurements and comparison with the interpretation of other Jurassic deposits, reaches conclusions similar to those of Neagu et al. (1983) concerning the inner to middle shelf environment represented by the gray shales. The genusEpistomina is considered to represent open marine shelf conditions during the Jurassic (Shipp, 1989). The paleoenvironmental range of Lenticulina ex gr. muensteri, a foraminifer species that dominates sample 11 from the Strungulita section, is considered to span the entire shelf (Johnson, 1976). However, this species has been reported as dominant in the shallow-water assemblages of the Lower Inferior Oolite (Bajocian) of England (Morris, 1982), as well as in other Middle Jurassic near-shore marine sediments of Great Britain (Morris & Coleman, 1989). Tudoran & Hazel (in press) have shown this species to have the highest frequency on the inner shelf in Toarcian deposits of the Apuseni Mountains (Romania). The diversity of the investigated foraminifer assemblages is low (5-11 species), and so is their heterogeneity (0.3-1.4). These values (fig. 5.2) are similar to those of assemblages from the Toarcian of Bratca, attributed to inner neritic paleoenvironments by Tudoran & Hazel (in press), characterized by diversities of 2-12 species and heterogeneities ranging from 0.7 to 1.7 . Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) C/) ÎF O IR A M H H H ip m IR A o 'B TT ITi A € O ID S % 8 M ■D & % k •3 cd .5 C i £ I S II II I l I -I î l "5 5% b) 5 (3 o 1 % l II I ! I 3. I 3" I II à; I CD 1 i L ± lÿ 9 I 29 .y io{ 9 sp 10^ 9 üp lot 9 sp log 9 sp loç 9 sp loy 9 .sp 10^ 9 ip 2f 9 1 ? 9 ,ip 10(9 59109 9 ;p lot 9 sp 109 9 .M) 10^ ■DCD O Q. 11 C a 3O "O 8 O CD Q. ■D CD (/) Fig. 5.2 Microfauna distribution and parameters in the Strungulita section. uî 76 The flood-like occurrence of Epistomina regularis in the first three samples collected from the gray shales marking the height of the late Bajocian transgression in the Strungulita section is very similar to reported flood occurrences of the genus Reinholdella in the Toarcian, also associated to transgressions, in Great Britain (Copestake & Johnson, 1989), western Europe (Ruget, 1985), and the Apuseni Mountains (Romania, Tudoran & Hazel, in press.)- Similar flood occurrences of Epistomina have been recorded in Middle and Upper Jurassic deposits, as shown in the review of Gordon (1970). Although the exact paleoecological factor involved is still elusive, the extremely abundant and abruptly-ending presence of the species Epistomina regularis might therefore represent an ecological epibole, in the sense of Brett (1995) - "thin stratigraphie intervals characterized by the anomalous abundance of species normally rare or absent", species which take advantage of rapid environmental changes associated to transgressions. The major transgression recognized in the Bajocian deposits of the Strungulita section is very likely to correspond to the important late Bajocian transgressive global event, whose expression was noted in England, Scotland, France, Germany, Crimea (Ukraine), Arctic Canada, Greenland, Chile and India (Hallam, 1988). This transgression is probably equivalent to that of the third-order cycle LZA-2.1 of Haq et al. (1988). From a sequence stratigraphie standpoint, the upper Bajocian gray shales from the Strungulita section represent the maximum flooding surface of a third-order sea-level cycle. The fining-upwards clastic deposits below it belong to a transgressive systems tract, whereas the coarser deposits on top of it (ending with the Tataru Peak Sandstone) can be assigned to a high-stand systems tract. The subaerial exposure surface at the top of the latter represents a sequence bundary, and the brown, ammonite-bearing mudsone corresponds to a transgressive systems tract. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 77 Paleobiogeography As previously mentioned, the composition of the foraminifer assemblages from the Bajocian of Strungulita section is very similar to those of the late Bajocian of Poland and Ukraine. According to the classification of Gordon (1970), the foraminiferal assemblages of Strungulita are boreal shelf assemblages - group A3a, characterized by the conspicuous presence of epistominids, accompanied by nodosariids. In the latitudinal and bathymetric zonation of Basov (1991), the Strungulita assemblages belong to the nodosariid-epistominid type, interpreted as corresponding to shelf deposits in subtropical and perhaps temperate areas, and to deeper waters in tropical areas when associated to planktonic forms. The north European affinities of the investigated microfauna point in the same direction as the Aaalenian-Bajocian ammonite fauna of the Romanian Carpathians, which is "of almost pure NW-European type, with only some very scarce Phylloceratids added" (Patrulius & Popa, 1971). The ostracod assemblages are dominated by species of the genus Lophocythere and Praeschuleridea, which are widely distributed in the Middle Jurassic epicontinental deposits of northern Europe. However, if all the foraminifer species identified in the present study in the Strangulita section are known from other areas of Europe, such is not the case of some ostracod species. Thegencn. Lophocythere and Palaeocytheridea are common in Middle Jurassic deposits of Germany (Malz, 1962, 1975), extra-Carpathian Poland (Bielecka et al., 1988), and Ukraine (Permyakova, 1974), but they are represented in the Strungulita section by species that are new to science. The presence of such species, known so far only from this location, indicates that although the microfauna investigated in the present study has strong paleobiogeographic affinities to northern Europe, a certain number of features particular to this area only do exist. The microfauna thus provides evidence for a Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 78 northern Tethyan location of the Central Carpathian Unit of the Eastern Carpathians during the Bajodan, but also for a certain regional isolation. Systematics Included in this chapter are only the taxa that are either controversial or left in open nomenclature. The generic systematics of foraminifers used in this study is that of Loeblich & Tappan (1988), whereas the classification for the ostracods is based on that set forth by Hazel (1983). Specimens are deposited in the Howe collection. Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana. Part 1. Foraminifera Order Foraminiferida Eichwald, 1830 Superfamily Nodosariacea Ehrenberg, 1838 Family VaginuUnidae Reuss, 1860 Subfamily Lenticulininae Chapman, Parr & Collins, 1934 Genus Lenticulina Lamarck, 1804 Lenticulina ex gr. m uensteri (Roemer, 1839) 1839 Robulina munsteri Roemer: 48, pl.20, fig. 29. 1975 Lenticulina muensteri Jendryka-Fuglewicz: 149, pl.8,9,10; pl.l 1, figs 1-6, pi. 19, pl.20, figs 1,2. 1989 Lenticulina exgr. muensteri Morris &Coleman: 214, pl.6.3.4, figs 1-4. Material: 1863 specimens Horizon: upper Bajocian Remarks: In the material from the Strungulita section, this group includes the species L muensteri (Roemer, 1939), L. subalata (Reuss, 1854), and L. acutiangulata (Terquem, 1864), the latter being the most abundant. The individual species have not been separated because in this context they do not hold any Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 79 individual biostratigraphic or paleoenvironmental significance A tendency to uncoiling is present in a small number of specimens. Suborder Robertinina Loeblich & Tappan, 1984 Superfamily Ceratobuliminacea Cushman, 1827 Family Epistominidae Wedekind, 1837 Subfamily Epistomininae Wedekind, 1837 Epistomina nuda Terquem, 1883 1883 Epistomina nuda Terquem: 376, pi. 5, fig. 1. 1969 Epistomina nuda Pazdro: 62, pi. 6, figs 1-3,6-8, pi. 14, fig. 6. 1983 Epistomina nuda Neagu etal.: pi. 1, figs 23-28. Material. 956 specimens Horizon, upper Bajocian Remarks. This species is used in this study in the sense of Pazdro (1969). Morris & Coleman (1989) consider the form attributed by Pazdro (1969) to this species as a "stratigraphycally old form of E. stelligera" and use this name for what they consider to be a different smooth species of Epistomina. Part 2. Ostracods Class Ostracoda Latreille, 1806 Order Podocopida Muller, 1894 ?Suborder Podocopa Sars, 1865 Superfamily Cytheracea Baird, 1850 Family Progonocytherldae Sylvester-Bradley, 1948 Subfamily Progonocytherinae Sylvester-Bradley, 1948 Genus Lophocythere Sylvester-Bradley, 1948 Lophocythere sp. 1 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 80 Pl. 13, figs 29-30 Material. 131 carapaces, 222 valves. Horizon, upper Bajocian. Description. A species of Lophocythere in which the small bifurcating ridge of the anterocentral area is always in contact with the anterior ridge. The posterodorsal small ridge is U-shaped, the U pointing towards the posterior. The ventral part of the U is undulated and the dorsal part of the U is less prominent on the left valve. Remarks. This species is close to L. ostreata (Jones and Sherbom, 1888), but differs from it in the lack of reticulate ornamentation and the position of the small ridges in the antero-central and dorso-posterior areas. Lophocythere sp. 2 PI. 13, fig. 32 Material. 12 carapaces, 65 valves. Horizon, upper Bajocian. Description. A species of the genus Lophocythere with smooth valves, except for the ridges typical for the genus (one that runs from the ocular tubercle along the anterior side and then along the ventral side, and another in the ventro-central part, also running parallel to the ventral margin). A slight inflexion is present in the central- posterior part but it does not really become a ridge. Lophocythere sp. 3 PI. 13, fig. 31 Material. 16 carapaces, 43 valves. Horizon, upper Bajocian. Description. A species of the genus Lophocythere which has, apart from the ridges characteristic of the genus, an obvious ridge in the central part, starting in the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 81 anterior part from the same point where the other ridges meet and interrupted in the central part. The dorsal margin is slightly convex, not concave as is generally the case with the genus Lophocythere. Family Trachyleberididae Sylvester-Bradley, 1948 Subfamily Protocytherinae Lubimova, 1955 Genus Palaeocytheridea Mandelstam, 1947 Palaeocytheridea sp. i Material. 2 valves. Horizon, upper Bajocian. Description. Valves smooth, with straight median ridge and short antero-dorsal ridge in the shape of the letter S. Remarks. This species is similar to P. rara Permyakova, 1974 from the upper Bajocian of Ukraine, due to its smooth surface and straight median ridge, but differs from it in the shape of the small antero-dorsal ridge, which is also not bifurcated. Palaeocytheridea sp. 2 Material. 5 valves. Horizon, upper Bajocian. Description. Valve surface reticulated, with both median ridge and short antero- dorsal ridge straight. Remarks. This species is similar to P. priva Permyakova, 1974 from the lower Bathonian and P. subtilis Permyakova, 1974 from the upper Bajocian of Ukraine, but differs from the first in having an antero-dorsal small ridge separated from the median ridge, and from the second in having a antero-dorsal small ridge that is not bifurcated. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6. BATHONIAN - CALLOVIAN (MIDDLE JURASSIC) FORAMINIFERA AND OSTRACODS FROM ROMANIA Lithology and biostratigraphy The present study investigates the microfauna of Bathonian - lower Callovian deposits of sections Bigar and PiatraTasaul, and of well Vinderei IP South (fig. 1.3). The Bigar section is located I km south of the village Bigar, on the road leading to Berzeasca, within the Danubian Autochthon of the Southern Carpathians. The investigated deposits of the Bigar section conformably overlie limestones of Bajocian - early Bathonian age and are represented by 700 meters of gray marls with intercalated mudstones (fig. 6.1). These deposits have been referred to as the Bigar beds (Mutihac & lonesi, 1974; Tataram, 1984). A late Bathonian - early Callovian age was assigned to them based on the presence of the bivalve Bositra buchi and the ammonite Macrocephalites macrocephalus (Mutihac & lonesi, 1974). These deposits are conformably overlain by red nodular limestones with a rich ammonite assemblage, belonging to the late Callovian and early Oxfordian. The Piatra Tasaul section is located 3 km east of the village of the same name, on the Cismelei Valley, within the Central Dobrogean Massif. In this section (fig. 6.2), the upper Bathonian-lower Callovian deposits directly overlie Precambrian crystalline schists and are represented by 3 meters of yellowish wackestones and mudstones, representing the "basal detritic horizon" (Barbulescu, 1971). The age assigned by this author to the deposits is based on a rich assemblage of brachiopods and bivalves, including the species Bositra buchi. These deposits are unconformably overlain by Oxfordian bioclastic limestones. The Vinderei IP South well is located in the vicinity of the village of Vinderei, within the Barlad Depression (Scythian Platform). In this well, the Bathonian deposits unconformably overlie Triassic marls and sandstones and are represented by 770 meters of dark gray and black marls and mudstones (fig. 6.3). Their age has 82 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. S3 been assigned based on the presence of the bivalve Bositra buchi and an unspecified micropaleontologicai assemblage (Mutihac «S: lonesi, 1974). The three core samples investigated here are located at depths of 1468, 1684 and 1828 meters. The foraminifer and ostracod assemblages identified in the present investigation in sections Bigar and Piatra Tasaul, and well Vinderei IP South are listed in Appendix B. A number of specimens of the bivalve Bositra buchi (Roemer, 1836) have been found in sample 3 (1828 m) from the well Vinderei IP South, this bivalve species is also reported by previous studies from the Bigar beds and the upper Bathonian-lower Callovian deposits of Piatra Tasaul (Mutihac & lonesi, 1974; Barbulescu, 1971). The known ranges of the identifred microfaunal species confirm the late Bathonian - early Callovian age of the investigated deposits, based on macrofauna. Among the most useful index fossils are Lenticulina quenstedti, L. tricarinella, and Palaeomiliolina czestochowiensis (foraminifera), and Fithrbergiella (Fuhrbergiella) transversiplicata, Micropneumatocythere brendae, Praeschuleridea subtrigona, and Cytherella perennis. The presence of the foraminifer species Lenticulina quenstedti and L tricarinella in the upper Bathonian deposits of Bigar and Vinderei represent the earliest stratigraphie occurrence of these species in Jurassic deposits from Romania. Taphonomic observations The preservation of the microfauna from the Vinderei well is good, whereas that of the microfauna from the Bigar and Piatra Tasaul sections is poor. The microfossils of the Bigar section are strongly affected by processes of partial dissolution and recrystallization. The percentage of fragmented foraminifer specimens is low in the material from Bigar (15-23%) and Vinderei (8-17 %), suggesting low-energy environments, and higher in that from Piatra Tasaul, indicating a higher energy level of the depositional environment. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 84 Macrofauna: Kinuneridgian - red limestones upper Oxfordian B T50m Macrocephalites macrocephalus I I -73/91 gray marls with I intercalated mudstones -71/91 Phylloceras kudematschi Oecotraustes baklovi 1 -69/91 Bositra buchi I '-67/91 -61/91-63/91 •60/91 Ia -b lower Bathonian- gray limestones Bajocian microconglomerates Aalenian ■ and sandstones Fig. 6.1 Lithostratigraphic column of Bigar section. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 85 Macrofauna; CoUyrites ellipticus grainstones Belemnites canaliculatus fIm Homomya gibbosa sandstones with Anabada orbulites i intercalated maris Bosüra buchi II -A crystalline schists i N/S/VN/V/S(A Fig. 6.2 Lithostratigraphic column of section Piatra Tasaul. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 86 0 m Macrofauna: iffleRBHBRBRC Igggggg laaaaag taaaaaï fg g g g g t rhythmicaOy alternating packages of sands, Pliocene #aaaaa$ xaaaaa* marls and shales laaaaat maaaa* xaaaaax Z maaaax laaaaat m aaaaî iâaaaitt iaaaaag O 654 m O Z calcareous and siliceous sandstones alternating with organic limestones Samatian and yellow marls 1170 m sandstones with fragments of carbonizated Badenian vegetal remains and intercalated marls 1274 m Callovian compact dark gray shales 1400 m - 14671470m, sample 1 u compact dark gray shales, sometimes sandy % % - 1683 1685m, sample 2 < late dark gray shales and frne sandstones Bathonian OS - 18271829m, sample 3 Bositra buchi a dark gray shales 2170 m compact gray marls and thin sandstones TRIASSIC 2212 m compact calcareous sandstones CARBONIFEROUS alternating with shales and sandy shales Fig. 6.3 Lithostratigraphic column of well Vinderei IP South. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 87 Cementation of internal spaces of the foraminifera from the investigated sections with carbonate material is always present. Pyritization of foraminifera occurs rarely and only in the material from well Vinderei. Most of the ostracods from Vinderei are completely pyritized. In this material virtually all the ostracods (pyritized or not) are preserved as carapaces. The specimens of the bivalveBositra buchi found in sample 3 (1828 m) from Vinderei are well preserved; they occur in about equal proportions as disarticulated valves and complete shells. In the latter case the valves are always open. Paleoenvironments The foraminifer assemblages fiem Bigar and Vinderei are very similar. The most important components are nodosariids (among which the Lenticulina muensteri group is the most important), closely followed by ophthalmiids, spirillinids and Paalzowella feifeli. The diversity and heterogeneity of the Vinderei and Bigar foraminifer assemblages are high (Vinderei; 19-21 species, and respectively 1.9-2.1; Bigar. 17-23 species, respectively 1.8-2.2). The values of these microfaunal parameters, correlated with low values of fragmentation, are similar to those assigned by Tudoran & Hazel (in press) to middle and outer shelf assemblages from the Toarcian of the Apuseni Mountains (Romania). This interpretation corresponds to that usually given to the fine clastic sediments withBositra (= Posidonia), widely developed in the Tethys area during the Toarcian and Middle Jurassic. These deposits are very often rich in organic matter and yield poor benthic assemblages, with the exception of the bivalve Bositra, abundant at certain levels. These features allowed the deposits to be interpreted as representing deeper-water, usually dysaerobic shelf environments and have prompted the hypothesis of a nektoplanktonic mode of life for the species of Bositra (Jefferies & Minton, 1965). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 88 According to Jefferies & Minton (1965), the macrofauna of the classic Bositra buchi facies (shale, often bituminous, associated with mudstone) consists almost exclusively of Bositra buchi and ammonites. Ammonites have not been yet found in the upper Bathonian-lower Callovian deposits of the Barlad Depression (known only from borehole material), and are rare in the Bigar marls of the Southern Carpathians. However, rhyncholites (cephalopod jaws) have been recovered in the present investigation from the Bigar material. The presence of rhyncholites (consisting of calcite) in the lack of the ammonite shells (of aragonitic nature) might be explained by differential solution (Jefferies Sc Minton, 1965). Since a larger part of the bottom core (1827-1829m) from the Vinderei well was available (25 cm), it was possible to sample separately a level of dark gray marl, displaying a moderate amount of bioturbation, and a level of black marl with parallel lamination and lacking bioturbation. The foraminifer assemblage of the black, bioturbation-free level is dominated by the same groups as the other assemblages, but is characterized by a significantly lower diversity and abundance, as well as by the small size of the specimens (<250[i). Such dwarf faunas have been reported in the lower Toarcian of southwestern Germany (Riegraf, 1985), Central Italy (Bartolini et al., 1992), and Apuseni Mountains (Tudoran Sc Hazel, in press), and interpreted as a reaction to dysaerobia. The presence in deposits belonging to the "classic" facies with Bositra, such as those from Vinderei, of alternating levels with normal and dwarf microfauna confirms the ecological reappraisal of this type of facies by Kauffman (1981). This author suggests that the environment of the German Toarcian Posidonienschiefer, previously considered anoxic and inhospitable to benthic life actually represents a succession of environments with oxygen content varying up to moderate levels, and only episodic, short term anoxic intervals. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 89 The foraminifer assemblage from PiairaTasauI is very different from those of Bigar and Vinderei, being characterized by low diversity (6 species) and heterogeneity (LI). These values of the microfaunai parameters, the lack of ammonites and the important clastic component of the deposits strongly suggest a nearshore environment, characteristic of the early stages of the transgression that resulted in the first overlap of the Precambrian crystalline schists by Mesozoic marine deposits. The assemblage of PiatraTasaul is largely dominated by nodosariids (belonging especially to the genus Lenticulina), whereas cytherellids{Cytherella, Cytherelloidea) represent the most important component of the ostracod assemblage. However, the most significant species is the foraminifer Pseudocyclammina maynci, characteristic of Middle Jurassic carbonate platforms. This species has been so far reported from Romania only from the Callovian-Oxfordian carbonate platform of the Persani Mountains (Eastern Carpathians) by Dragastan (1980). Eustatic context Fine clastic deposits with Bositra buchi, often but not always organic-rich and showing little bioturbation, are very common during the Middle Jurassic, and especially the Bathonian-Callovian interval, on both the northern and southern margins of the Tethys. Jefferies & Minton (1965) make mention of the classic Bositra buchi facies (shale, often bituminous, associated with mudstone) in the Middle Jurassic of south-east France, the Oriental Alps, the Carpathians, Lombardy, Peninsular Italy, Greece and Albania, the Betic Cordillera, Morocco and Algeria, Anatolia, the Crimea, the Caucasus, Azerbaidjan, Iran and Iraq, Kenya and Tanzania, the Southern Andes and Indonesia. On the territory of Romania, fine clastic deposits with Bositra buchi, bituminous or not, are very common in the Bajocian-Callovian interval, as well as the deposits developed in the Klaus facies (red and brown limestones with ammonites, brachiopods and Bositra buchi, first described in the Oriental Alps). Bositra buchi Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 90 marls and shales are known from the Bucovinic suite (Haghimas Mountains, Bucegi Mountains) and Transylvanian suite (Persani Mountains) of the Eastern Carpathians, the Getic nappe (Resita area) and the Danubian Autochthon (Bigar area, Cema area) of the Southern Carpathians, the Scythian Platform (Barlad Depression, Predobrogean Depression), the western part of the Moesian Platform (Badaluta et a/., 1969; Mutihac & lonesi, 1974; Tataram, 1984). Only the occurrences from the Barlad Depression and Moesian Platform fully correspond to the classical Bositra buchi facies, having a significant content of organic matter. In most of the tectonic units of Romania, the Middle Jurassic deposits unconformably overlie older deposits, both in the Carpathian (the Bucovinic suite, Bucegi Mountains, and the Persani Mountains of the Eastern Carpathians) and foreland units (Moesian Platform, Central Dobrogean Massif, Scythian Platform). In some cases (Scythian Platform, Central Dobrogean Massif) the upper Bathonian deposits directly overlap crystalline schists. In all of the aforementioned cases, the upper Bathonian-lower Callovian deposits can be interpreted as generally representing deeper-water environments than the preceding deposits, which are usually coarser elastics. The widespread deposition of theBositra buchi facies might therefore be the expression of a major late Bathonian sea-level rise. The eustatic curve proposed by Hallam (1988), corresponds to this conclusion, indicating a significant sea-level rise for this time interval, based on transgressive/deepening events recognized in northern Europe, Greenland, Arctic Canada, Saudi Arabia, northern and eastern Africa, and India. The late Bathonian is a time interval for which the eustatic sea-level curve of Haq et al. ( 1988), differs significantly from that of Hallam (1988), and from the results of the present study, indicating an lower sea-level than during the early Bathonian. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 91 Paleobiogeography All foraminifer species present in the investigated material were first described in Jurassic deposits of northwestern Europe, and many were thought to be characteristic of this area only. However, as micropaleontological data concerning the Jurassic deposits from the southern Tethyan margin became increasingly available in the last decades, it became obvious that fine clastic deposits of the south-Tethyan shelf are characterized by foraminifer assemblages very similar to their northern counterparts. Important Middle Jurassic foraminifer species identiEed in the present investigation, such as Lenticulina tricarinella, L. muensteri, L, varions, L. quenstedti, Citharina clathrata, Saracenaria oxfbrdiana, Epistomina mosquensis, Planispirillina granulosa, and Ophthalmidium strumosum, have been reported from the south- Tethyan shelf (Musacchio, 1979 - Argentina; Kalia & Chowdhurry, 1983 - India; Karega, 1990 - Tanzania). The only foraminifer species present in the investigated material whose geographic range seems to be limited to northern Europe is Paleomiliolina czestochowiensis, first described in extra-Carpathian Poland. The only agglutinated foraminifer with complex internal structures identified in the investigated material is Pseudocyclammina maynci, from the upper Bathonian-lower Callovian of Piatra Tasaul. During the Lower Jurassic, the north-Tethyan margin is characterized by the absence of such foraminifera, but during the Middle Jurassic some of the representatives of this group colonized the north-Tethyan margin. However, Pseudocyclammina maynci is a cosmopolite species (Bassoullet et aL, 1985), frequently reported from both Tethyan margins. During the Middle Jurassic, provincialism is significantly stronger among ostracods than among foraminifera. A number of genera very common on the north- Tethyan shelf and present in the material investigated by this study, such as Micropneumatocythere, Schuleridea, Praeschuleridea, Ektyphocythere, Cy the relia, and Cytherelloidea have been reported from Jurassic deposits of the southern Tethyan Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 92 shell (Basha, 1980 - Jordan; Rosenfeld e ta l., 1987 - Egypt; Depeche et aL, 1987 - Saudi Arabia; Ballent, 1991 - Argentina). However, at the species level the south- Tethyan ostracods assemblages are in most cases characterized by taxa that are not found on the north-Tethyan shelf. The ostracod assemblages investigated in the present study display strong affinities with those known from northern Europe (Great Britain, Germany, Poland, Ukraine). Some of the ostacod species present have been so far reported only from Poland {Cytherella perennis, Bythocyprisl jaworznikensis, Paracypris procera) or Ukraine {Palaeocytheridea subtilis). Systematics Included in this chapter are only the taxa that are either controversial or left in open nomenclature. The generic systematics of foraminifers used in this study is that of Loeblich & Tappan (1988), whereas the classification for the ostracods is based on that set forth by Hazel (1983). Specimens are deposited in the Howe collection. Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana. Part 1. Foraminifera Order Foraminiferida Eichwald, 1830 Suborder Robertinina Loeblich & Tappan, 1984 Superfamily Ceratobuliminacea Cushman, 1827 Family Epistominidae Wedekind, 1837 Subfamily Epistomininae Wedekind, 1837 Epistomina nuda Terquem, 1883 1883 Epistomina nuda Terquem: 376, pi. 5, fig. 1. 1969 Epistomina nuda Pazdro: 62, pi. 6, figs 1-3,6-8, pi. 14, fig. 6. 1983 Epistomina nuda Neagu et aL: pi. 1, figs 23-28. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 93 Horizon, late Bathonian of Vinderei. Remarks. This species is used in this study in the sense of Pazdro (1969). Morris & Coleman (1989) consider the form attributed by Pazdro (1969) to this species as a "stratigraphycally old form of E. stelligera" and use this name for what they consider to be a different smooth species of Epistomina. Part 2. Ostracods Class Ostracoda Latreille, 1806 Order Podocopida Muller, 1894 ?Suborder Podocopa Sars, 1865 Superfamily Cytheracea Baird, 1850 Genus Cytherella Jones, 1849 C ytherella aff. C. p e re n n is Blaszyk, 1967 1967 Cytherella perennis n. sp. Blaszyk; p. 16. pi. II, fig. 1-11; pi. HI, fig. 6-7. 1988 Cytherella perennis Blaszyk: p. 169, pi. LXV, fig. 3. Horizon, late Bathonian-early Callovian of Bigar and Piatra Tasaul. Poland: middle-upper Kuiavian - Bathonian; NW Germany: Bathonian (parkinsoni); Extra- Carpathian Poland: middle Kuiavian - Bathonian. Remarks. Carapace beanlike in lateral outline, smooth, anterior and posterior ends uniformly rounded. The real difference between C. perennis and C. limpida is that C. limpida has fine parallel ribs on the anterior roll-like thickening. These fine ribs were not observed so the difference was made assigning the specimens with a higher anterior part to C. limpida and those truly beanlike to C. perennis. C ytherella aff. C. lim pida Blaszyk, 1967 1967 Cytherella limpida n. sp. Blaszyk: p. 13, pi. I, figs. 2-13; pi. II, figs. 12. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 94 Horizon. Extra-Carpathian Poland: Kuiavian (upper Bajocian)-Bathonian; NW Germany: Bathonian {parkinsoni). 1988 Cytherella limpida Blaszyk: p. 168, pi. LXV, fig. 2. Remarks. These specimens have an assymetric lateral outline (anterior part higher) and were therefore assigned to C. limpidai however, the real difference between C perennis and C. limpida is that the latter has One parallel ribs on the anterior roll-like thickening. Suborder Podocopina Sars, 1866 Superfamily Bairdacea Sars, 1888 Family Bairdiidae Sars, 1888 Genus Bythocypris Brady, 1880 Bythocyprisl jaworznikensis Blaszyk, 1967 1967 Bythocyprisl jaworznikensis n. sp. Blaszyk: p. 19, pi. HI, figs. 1-5. 1988 IBythocypris jaworznikensis Blaszyk: 169, pi. 661, fig. 1. Horizon, late Bathonian of Vinderei. Extra-Carpathian Poland: middle Kuiavian-Bathonian. Remarks. The general shape of the investigated specimens is similar to this species, including the overlap of the left valve over the right one on the ventral side (especially in the central part). However, the dorsal margin is rather rounded than subangulate. ?Suborder Podocopa Sars, 1865 Superfamily Cytheracea Baird, 1850 Family Protocytheridae Ljubimova, 1955 Subfamily KIrtonellidae Bate, 1963 Genus Ektyphocythere Bate, 1963 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 95 Ektyphocythere nucleopersica Blaszyk, 1967 1967 Ektyphocythere nucleopersica n. sp. Blaszyk: p. 50, pl. XVm, figs. 1-3. Horizon, late Bathonian of Vinderei. Extra-Carpathian Poland: lower and middle Bathonian. 1988 Ektyphocythere nucleopersica Blaszyk: p. 175, pi. LXXI, fig. 3. Remarks. The investigated specimens are very similar to this species, including the slightly concave dorsal part, posterior end acute, and a lateroventral ridge formed by ventral ribs. Family Cytherideidae Sars, 1925 Subfamily Galliaecytherideinae Andreev & Mandelstam, 1964 Genus Pichottia Oertli, 1959 Pichottia elegans Ware & Whatley, 1980 1980 Pichotia elegans sp. nov. Ware & Whatley: p. 201, pi. 1, figs. f-j. Horizon, late Bathonian of Vinderei. England: upper Bathonian Remarks. General shape very similar elongated, extremities below midheight, ventral margin very slightly overhung ventrolaterally. However, dentition could not be observed; the ventral side is ornamented with very fine striae, parallel to the ventral margin. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 7. OXFORDIAN-iOMMERIDGIAN (UPPER JURASSIC) FORAMINIFERA AND OSTRACODS FROM THE PREDOBROGEAN DEPRESSION (SCYTHIAN PLATFORM, ROMANIA) Geologic setting and Uthology The Predobrogean Depression is located between the East European platform to the north and the North Dobrogean Orogen to the south, being separated from the latter in the Danube Delta area by the Sf. Gheorghe fault The Predobrogean Depression has been interpreted either as a foredeep of the North Dobrogean Orogen or as an intracratonic depression (Mutihac & lonesi, 1974; Patrut et a i, 1983). The Upper Mesozoic sedimentary cover consists of Middle Jurassic to Lower Cretaceous deposits, unconformably overlain by Middle Miocene to Pliocene deposits. The Caraorman West FI 1/7 well is located between the Sulina and Sf. Gheorghe arms of the Danube, whereas the Crasnicol F6I808 well has a more southern position, in the immediate vicinity of the Sf. Gheorghe fault (fig. 1.3). As shown by Patrut et al. ( 1983), the Mesozoic deposits are lifted in the vicinity of the Sf. Gheorghe fault, a situation reflected by the Miocene overlapping the upper Oxfordian in the Caraorman West FI 1/7 well and the lower Oxfordian in the Crasnicol F61808 well (fig. 7.1). The oldest Jurassic deposits recovered from the Caraorman West FI 1/7 well consist of 6 meters of alternating dark green shale and gray to red sandstone, the latter with oblique and parallel lamination, ripple marks and frequent fragments of carbonized vegetal matter. Next are 16 meters of dark gray to green compact shale, with a 15 cm thick intercalation of gray mudstone in the upper part. The succession continues with 7.5 meters of gray to red limestone, often oolitic, with intercalated dark green shales, followed by I meter of microconglomerate and conglomerate with limestone elements. The youngest Jurassic deposits are represented in this well by 1.5 meters of upwards-fining sandstone, followed by Im of compact, gray siltic shale. The lithology of the Jurassic deposits from the Crasnicol F61808 well is much more uniform, consisting of 90 meters of compact, dark gray shale with intercalated 96 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 97 milimetric and centimetric siltstones and fine sandstones, with parallel and oblique lamination and ripple marks, sometimes with fragments of carbonized vegetal matter. Biostratigraphy The microfaunai assemblages identified in the investigated wells is listed in Appendix B. The small number of ostracods recovered from the Crasnicol F61808 well could not be identified due to poor preservation. As the Jurassic deposits of the Predobrogean Depression are known only firom wells, their biostratigraphy is based mainly on microfauna. Ammonite assemblages have been described from the area between the Prut and Dnister rivers (Romanov & Danitch, 1971). During the present investigation, rare ammonites have been recovered from the cores of the Crasnicol F61808 well, but they have not been yet identified. The ranges of the most important foraminifer and ostracod species identified in the investigated material, compared to the total ranges known firom the literature, are shown in figure 7.2. Ammonite assemblages indicating an early Oxfordian age have been reported by Romanov & Danitch (1971) from deposits of the Predobrogean Depression very similar in lithology and microfaunai content to those intercepted by the Crasnicol F61808 well. The foraminifer assemblage present in the deposits of the Crasnicol F61808 well indicates an early Oxfordian age, due to the presence of the species Pseudolamarckina rjasanensis and Ophthalmidium compressum. According to Stam (1986) the former species ranges as high in the stratigraphie record as the early Kimmeridgian, in Portugal and the Grand Banks of Newfoundland. However, the range of this taxon is restricted to the Callovian in the East European Platform (Grigelis, 1985), and to early Callovian - early Oxfordian in the Lesser Caucasus (Todria, 1991). Ophthalmidium compressum appears to be a good index fossil, since its range is limited to the early Oxfordian in Great Britain (Shipp, 1989). This species is also recorded from the Predobrogean Depression with the same stratigraphie range Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 98 by Romanov & Danitch (1971) under the name Spirophthalmidiian bolgradensis. These authors mention the presence of the species Discorbis paraspis from the same stratigraphie level, but this species was not identified in the material from the Crasnicol F61808 well. From a biostratigraphic viewpoint, the foraminifer assemblages of the Caraorman West FI 1/7 well are clearly divided in two groups. The first group includes the assemblages yielded by the deposits older than the oolitic limestones (fig. 7.3). The species Ophthalmidium compressum is absent, although another species of this genus is present, suggesting that this absence is not paleoenvironmentally-driven and that the deposits are younger than the early Oxfordian. The presence of the species Spirillina andreae and Patellinella cristinae provides evidence for the middle Oxfordian age of these assemblages. The former taxa has been so far reported only in the uppermost lower and middle Oxfordian deposits of Poland (Bielecka, 1988) and the middle Oxfordian of Georgia (Todria, 1991). The latter species is known only from the uppermost lower to the lowermost upper Oxfordian (Bielecka, 1988). The speciesDiscorbis paraspis and D. subspeciosus are present in all the assemblages of the Caraorman West FI 1/7 well. The former species is widespread during the Oxfordian throughout the Tethys and adjacent areas and a total range zone defined using its occurrence has been proposed by Moullade (1984). However, Stam (1986) has shown that the total range of this species in the Jurassic deposits of Portugal and the Great Banks (Canada) is significantly larger (Bathonian - Kimmeridgian) and therefore that interval range zones are of little value in the case on Jurassic benthic foraminifera, which are usually long-ranging and display local range variation. The second group of assemblages present in the Caraorman West FI 1/7 well, beginning with the first level of oolitic limestones (fig. 7.3), is characterized by the presence of agglutinated foraminifera with complex internal structures, such as Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 99 Alveosepta jaccardi, Nautiloculina cf. N. oolithica, Everticyclammina virguliana, and Mesoendothyra àjianiana. One should note that the presence of this type of foraminifera is linked with the development of carbonate platforms and therefore the first occurrence of such taxa is strictly facies-driven and does not necessarily represent an evolutionary event. In fact, all four aforementioned species are known to occur before the late Oxfordian, but they are reported from the East European Platform as well as Crimea, Caucasus and many areas of Central Asia only from the late Oxfordian (Ascoli & Grigelis, 1993; Todria, 1991). The only exception is Alveosepta jaccardi, which occurs in the Caucasus beginning with the middle Oxfordian, but becomes abundant only beginning with the late Oxfordian. In the northeastern Caucasus, the assemblage withAlveosepta jaccardi, Nautiloculina oolithica, Everticyclammina virguliana, and Mesoendothyra izjumiana corresponds to the late Oxfordian (Bimammatum ammonite zone) and the entire Kimmeridgian (Todria, 1991). In the Predobrogean Depression, Romanov & Danitch (1971) have described ammonite assemblages indicative of the Transversarium and Bimammatum zones (late middle and late Oxfordian) as well as of the early Kimmeridgian from shales with intercalated limestones, an interval that corresponds to the entire sequence present in the Caraorman West FI 1/7 well. Given that the age of the shale that yielded the assemblage including Spirillina andreae and Patelinella cristinae has been shown to be middle Oxfordian, the overlying oolitic limestones and associated shales with agglutinated foraminifera with complex inner structure from the Caraorman West FI 1/7 well can be assigned to the late Oxfordian - early Kimmendgian. It is therefore possible to divide the stratigraphie interval covered by the two investigated wells in the following three assemblage zones: - Ophthalmidium compressum assemblage zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C 3 Q. ■D CD WELL CARAORMAN WEST FI 1/7 Om C/) C/) i coarse sand ...... WELL CRASNICOL F61808 CD ISm ...... 8 ...... fine sand ...... Mim I gray silt Tine sand and gray silt 3. 3 " CD I fine gravel and sand ■DCD O Q. I C a coarse sand 3o "O ;j^.io3....„coarsc green sandstone o IT rn5m| I gravel and gray shale M' m and microconglomerate., with reworked elements ooliihic limestones with •1*6 of limestone and dark CD Q. intercalated marls ' brown marl nfyn. Ml •2M. :iW 2M •217 ...... •*»^234 compact dark brown and gray marl •244 compact gray and green marl with ■D ' ^ 246 with intercalated fine sandstone CD intercalated sandstone and mudstone WiViVfi •2S3 •260 C/) 271 C/) I,'166263" •276'1 » •«2R9m*< •203 Fig. 7.1 Lithostratigraphy of the deposits from wells Caraorman West FI 1/7 and Crasnicol F61808 8 101 u VOI 1 •oI m uouD fp B jtaiduj c DMtjpoai Cif) m u o i s p ^ n es sistàtauop inpuftfiiCsmiivo oum adof »j9tp<3mp3[j om jo o tn p ito gj9tp& >ai\fdofi tpuSau idaodioj u tm Suoj» D utjiytds sisuxaios maiotpoj± ooissàmf outpoopnamnQ § ouotjnSjtA üuiuauopXsûiMj snsttpâdsqns nqjtastci 30upsup oiputpiDd atm puo vu ijju td s Duotumla nt/imopuaonfn ii tptvxm f vtdasoMfy oiptnqim oipMOipoj osojnpou vu^otpoj£ unasajdiuoD ttimpmioiftt(do I DOKsmhtouopwax ppoyaifi mnSjpnoQ cS mtDtpjofico vuvttxnuos nrnttj omuiuiopdaopnarj vidKtoa nurpotiuaq nsuauDsvCt Duapjoumjopmsj I 'z-dsmpiojpuiA ■s ojaSiiptmtod Dunaoistds stsianbtoui Dutuioitidj nnnnmjSSo sattpooqotmuy I sid so ^ stq^oastQ ojiamjmia mnpattuiri 'ipjiaf oipMOZioj |l tum vuuta umtpitujmflifdo ttpajsuanb m npotaari oattpijoo tnttpooinnon I I sntuofitptiojdoa mtpooqowufy l i ii CS K 00 iZ Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) OSTRACODES" INFERRED C/) I FIRST OCC.. HETERO FRAGMEN DIVERII FIRST OCC,- RELATIVE SEA-LEVEL ABUNDANCE DIVERSmr ABUNDANCE LASTOCC. OENEITY TATION SITY II LASTOCC VARIATION 0 2» 40 M W 20 10 0 10 20 0 20 4 «0» 0 20 40 60 00 0 1 - I I I I aasaRRay ■D8 ooO^Mnwloo* a Nüüi 3. 3 " fimwmRoml CD ■DCD O Q. C a 3O "O O «lUiotinIniwliu CD Q. (iwiiiOcroriptdimM) (iwinkcroffpiân) (iHimbtror iÿNlimM) iptdi*) ^§m arl sandstone mudstone BQj oolithic llmestonek*jl microcongiomerate sequence boundary ■D CD 1ST = transgressive systems tract HS = high-stand systems tract iliil maximum flooding surface C/) C/) Fig. 7.3 Lithology and microfaunai parameters of the Upper Jurassic deposits from well Caraorman West FI 1/7. 103 Definition: defined by the presence of the characteristic species Ophthalmidium compressum, Pseudolamarckina rjasanensis, Vinelloidea sp. 2 Danitch, 1971, and Lenticulina quenstedti. Range: early Oxfordian. - Spirillina andreae assemblage zone. Definition: defined by the presence of the characteristic species Spirillina andreae, Patelinella cristinae, Ophthalmidium carinatum, Discorbis subspeciosus, and Haplophragmoides canui. Range: middle Oxfordian. -Everticyclammina virguliana assemblage zone. Definition: defined by the presence of the characteristic species Everticyclammina virguliana, Alveosepta jaccardi, Nautiloculina cf. N.oolithica, and Mesoendothyra izjumiana. Range: late Oxfordian - early Kimmeridgian. The relationships between these assemblage zones and other microfauna-based biostratigraphic schemes for the same time interval is shown in figure 7.4. Paleoenvironments and sea-level variations The lower Oxfordian shales, siltstones and fine sands from the Crasnicol F61808 well can be interpreted as corresponding to an inner neritic depositional environment with prevailing siliciclastic sedimentation. Evidence for such an interpretation is provided by the frequent oblique lamination and ripple marks indicating currents, fragments of carbonized vegetal matter suggesting vicinity of source areas, as well as the microfaunai parameters. Diversity and heterogeneity of the foraminifer assemblages are low - between 4 and 19 species, with an average of 8 species for the former, and values of 1.1 to 2 for the latter. The percentage of fragmented foraminifer specimens is very high (30-52%). No paleoenvironmental trends are Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 104 apparent in the interval intercepted by the well, as lithologie, sedimentologic and microfaunai features are generally constant. The oldest deposits intercepted by the Caraorman West FI 1/7 well, consisting of 6 meters of alternating dadc green marls and gray to red sandstone, the latter with oblique and parallel lamination, ripple marks and frequent fragments of carbonized vegetal matter, are also interpreted as belonging to a shallow marine depositional environment (samples CW-254B through CW-266). Foraminifer diversity and heterogeneity are low - 8 to 18 species (fig. 7.3), and respectively 1.8 to 2.6, whereas the percentage of fragmented specimens is high (25-38%). The dark gray to green compact marls (samples CW-254 through CW-231) are characterized by high diversity (18 to 57 species) and heterogeneiQr (2.7 -3.3) and low levels of foraminifer fragmentation (9-14%). The fine clastic composition of the rocks of this interval, together with the values of microfaunai parameters, allow to interpret them as being deposited in a middle to outer neritic paleoenviromnent. In the upper part of these shales is located a 15 cm thick layer of indurated mudstone (samples CW-234, CW-236) with planktonic foraminifera (jGlobuligerina sp.) and radiolarians. This is the only level in both wells where planktonic foraminifera are present and is readily interpretable as resulting from a pelagic sediment, probably deposited in an outer neritic paleoenviromnent. Such deposits can be formed in much deeper environments, but the platform setting of the Predobrogean Depression during the Jurassic excludes the presence of paleoenvironments deeper than outer neritic. Absolute abundance of foraminifera is very high in sample CW-231, the closest to the mudstone level, probably indicating a certain amount of stratigraphie condensation. The oolitic limestones (samples CW-228, CW-224, and CW-221) have yielded agglutinated foraminifera with complex inner structure and are typical for reefal environments. The intercalated shales (samples CW-227, CW-222, and CW-215) are characterized by medium to high diversity (24 - 55 species) and heterogeneity (1.4 - Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 105 2.8). The percentage of fragmented foraminifer specimens is slightly higher than in the shales of the preceding interval (11-18%). These values of the microfaunai parameters, characteristic of open marine environments, indicate that the intercalated shales correspond to transgressive intervals. However, the constant presence of agglutinated foraminifera with complex inner structure in these deposits indicates not very deep envirorunents and/or proximity of reefal environments from which these forms might have been transported. The rate of faunal change, both for foraminifera and for ostracods, switches from positive values to negative ones between samples CW-231 and 227, corresponding to the change in lithology from shale to oolitic limestone. This appears to be due to the fact that he predominance of new occurrences is generally related to transgressions, whereas that of extinctions is associated with regressions (Copestake & Johnson, 1989). According to Boomer (1992), such increases in extinctions correspond to facies changes, in this case from siliciclastic to carbonate sedimentation. The microcongiomerate and calcareous breccia that overlies the youngest level of oolitic limestone is interpreted as deposited in a non-marine environment Next in the stratigraphie succession are sandstones that have yielded rare miliolid foraminifera (sample CW-205) and are interpreted as representing a inner neritic, high energy depositional environment The youngest Jurassic deposits of the Caraorman West FI 1/7 well consist of a shale level (sample CW-203) with a microfaunai assemblage of medium diversity (24 species), high heterogeneity (2.9), and low percentage of foraminifer fragmentation (16%), indicating deposition in an open marine paleoenvironment The shale intercalations in the basal coarse clastic interval (94-lOOm) might correspond to episodes of increased water depth, but their low thickness does not exclude the possibility that they might simply be the manifestation of lateral shifts of the local depocenter, in constant water depths. The overlying thick succession of dark Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 106 gray to green shale (79-94m) represent a gradual but significant increase in water depth, from inner-neritic to middle and outer neritic environments, culminating with the pelagic mudstone. The oolitic limestones represent a return to the shallow waters, in this case those of a carbonate platform, punctuated by short deeper water intervals corresponding to the intercalated shales. The layer of calcareous breccia and microcongiomerate provides evidence for subaerial exposure and reworking of the underlying oolitic limestones. The rining upwards succession of sandstone and shale that concludes the succession of Jurassic deposits in the Caraorman West FI 1/7 well marks a new water deepening interval, up to mid shelf depths. Given the time frame of the deposits intercepted by this well, which represent about 2.5 m.y., using the time scale of Harland et al. (1989), two third-order sea- level variation cycles can be identified in the deposits of the Caraorman West FI 1/7 well. The thick shales and perhaps also the underlying basal coarse elastics, both of middle Oxfordian age, can be assigned to the transgressive systems tract of the first cycle, with the maximum flooding surface corresponding to the pelagic mudstone (fig. 7.3). The shales overlying the mudstone, together with the oolitic limestones (of late Oxfordian and perhaps early Kimmeridgian age) represent the high-stand systems tract of the same third-order cycle, whereas the thin shales intercalated within the limestone (lower Khnmeridgian) might represent the manifestation of higher order sea-level cycles. The contact between the youngest oolitic limestones and the overlying non-marine calcareous breccia represents a sequence boundary and the transgressive systems tract of the second cycle includes the sandstone and shale from the top of the intercepted deposits. The comparison of the resulting relative sea-level curve for the Danube Delta sector of the Predobrogean Depression with existing eustatic sea-level curves indicates that a significant middle Oxfordian sea-level rise is documented worldwide (western Europe, northern Africa, the Gulf of Mexico, Alaska, Central Asia, northern India, Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 107 western Australia, and New Guinea) by Hallam (1988). Haq et al. (1988) also indicate a sea-level rise during the middle Oxfordian (third-order cycle LZA-4.3), but apparently of lesser amplitude. The early part of the late Oxfordian is interpreted by both Hallam (1988) and Haq eta l. (1988) as a sea-level fall, which corresponds to the presence of the oolitic limestones in the Predobrogean Depression, but the aforementioned authors also record a sea-level rise during the last part of the late Oxfordian, which cannot be recognized in the data of the present study. The areas where this sea-level rise is recorded by Hallam (1988) are limited in extent (western Europe and eastern Greenland). Both authors mention a sea-level rise during the early Kimmeridgian, after a sea-level fall at the Oxfordian/Kimmeridgian boundary. An excellent correlation exists between the relative sea-level curve recorded in the present study for the Danube Delta sector of the Predobrogean Depression and the eustatic curve proposed by Sahagian et al. (1996), based on data from the Russian platform. According to this eustatic curve, the entire middle Oxfordian corresponds to a major sea-level rise, which reaches its maximum at the boundary between the middle and upper Oxfordian. The late Oxfordian is represented as a generally regressive time interval, with two important sea-level falls. The early Kimmeridgian is characterized by another sea-level rise. Paleobathymetric model The bathymetric distribution of Jurassic microfauna is still poorly known, due to the lack of modem analogs (Brouwer, 1969; Copestake & Johnson, 1989). In this study, species belonging to the same genus (Spirillina, Epistomina, Discorbis, Paalzowella, Lenticulina) or group (miliolids, small agglutinants, large agglutinants with complex inner stmcture) that have a similar stratigraphie and quantitative distribution have been grouped together. Q-mode analysis of the samples from wells Crasnicol F61808 and Caraorman West FI 177, using as parameters the relative abundance of main foraminifer Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 108 components indicates the presence of three sample groups (fig. 7.5). Given the paleoenvironmental analysis previously conducted, these three groups were correlated to the following biofacies: - la. inner neritic, siliciclastic sedimentation: samples CW-266, CW-263, CW- 254B, CR-196, CR-2I0, CR-214, CR-217, CR-233, CR-234, CR-244, CR-246, CR-253, CR-260, CR-267, CR-269, CR-270, CR-271, CR-273, CR-276, CR-283. - Ib. inner neritic, carbonate platform: samples CW-227, CW-222, CW-215. - n . outer to middle neritic: samples CW-254, CW-244, CW-231. The R-mode cluster analysis of the foraminifer species and groups taken into account revealed the existence of three clusters. In order to facilitate the understanding of the relationships between the taxa and the biofacies, averages of the relative abundance of each species or group of species in the samples of each biofacies was computed and compared to the results of the R-mode cluster analysis (fig. 7.6). The first grouping includes taxa with high relative abundance in samples from the outer to middle shelf biofacies. Ammobaculites coprolith^ormis and Epistomina spp. have significant proportions only in this type of environment, which corresponds to previous interpretations of these taxa as deeper water forms (Barnard et aL, 1981 ; Stam, 1986). Spirillina spp. and Lenticulina spp. reach their highest frequency in deeper water environments, but they also represent a significant proportion of the inner neritic assemblages. Most of the taxa grouped in the second and third cluster, such aPaalzowella spp., the small agglutinants, miliolids and Ophthalmidium spp. are most frequent in shallow marine environments, with both siliciclastic and carbonate sedimentation. Miliolids and Ophthalmidium spp. cluster together, forming the third group mainly because they represent very high proportions in the assemblages of the Crasnicol F61808 well. The large agglutinants with complex internal structures, part of the second cluster, are restricted to reefal environments. This distribution generally Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 109 corresponds to that reported by previous studies (Dragastan, 1980; Barnard et aL, 1981; Stam, 1986). However, according to the results of this study, Discorbis spp. and Paalzowella spp. appear to also represent an important component of deeper water shelf assemblages. The inferred paleobathymetric distribution of the analyzed taxa is shown in figures 7.7 and 7.8. Outer neritic environments, investigated only in thin sections and therefore not subject to quantitative analysis, are characterized by the presence of planktonic foraminifera (plobuligerina sp.), radiolarians, and rare benthic foraminifera {Conicospirillina bassiliensis, Spirillina sp.). Paleobiogeography During the late Jurassic, the large agglutinated foraminifera with complex internal strucmres thoroughly colonize the north Tethyan margin, but their value as paleobiogeographic indicators appears to be limited, as most taxa of this group are cosmopolitan, being reported from both Tethyan margins (Bassoullet et aL, 1985). A possible criteria might be represented by the fact that theg&aexa. Alveosepta and Everticyclammina, very frequent throughout the north Tethyan margin, are much less abundant on the carbonate platforms of the Apulian block, part of the south Tethyan margin (Pelissie et aL, 1982). Both aforementioned genera are very abundant in the upper Oxfordian - lower Kimmeridgian deposits of the Predobrogean Depression, indicating a clear north Tethyan affinity. The speciesMesoendothyra izjumiana, first described firom the East European platform and encountered in the material investigated in the present study, seems so far to be limited in occurrence to the north Tethyan margin and can therefore be used as a paleobiogeographic indicator for this area. During the Kimmeridgian, the development of reefal facies with associated large agglutinated foraminifera reaches the highest paleolatitudes - slightly above 35°N (Bassoullet et aL, 1985) - favored by an increase in surface water temperature (Cecca et aL, 1993). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. no The calcareous foraminifera identified in the investigated material are very common on the north Tethyan shelf, in what is commonly referred to as the Boreal province. However, recent studies dealing with south Tethyan Jurassic siliciclastic deposits have identiried most of these species, providing evidence for the bipolarity of Jurassic foraminifer faunas (Kalia & Chowdhury, 1983). Only a very small number of species {Spirillina andreae, Patellinella cristinae) seem to be, according to the present knowledge, restricted in distribution, being reported only from southern Poland and Georgia. The Predobrogean Depression has therefore its strongest paleobiogeographic ties with the Polish sector of the East European Platform, Crimea, and Caucasus. Microfaunai similarities are less obvious between the Predobrogean Depression and the central parts of the Russian Platform, the latter being located north of the emerged Ukrainian shield and undergoing Arctic influences. Barbulescu & Neagu (1970) have described from the upper Oxfordian - lower Kimmeridgian reefal deposits of the Central Dobrogean Massif (located south of the North Dobrogean Orogen) a foraminifer assemblage consisting of nodosariids, spirillinids, involutinids and discorbiids. This assemblage is very similar, including at the species level, to those identified in the present investigation from the middle Oxfordian - lower Kimmeridgian of the Caraorman West 11/7 well. The major difference consists in the absence fiom the Central Dobrogean Massif of the large agglutinated foraminifera with complex internal structures, common to all carbonate platforms of the north Tethyan margin during this time interval. At the species level, the distribution of ostracods in the material investigated in the present study is less cosmopolitan than that of foraminifera. The species identified in the investigated material, such as Hechticythere serpentina, Nophrecythere cruciata alata, and Eripleura eleanorae are known only from the north Tethyan epicontinental basins. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Ill Systematics Included in this chapter are only the taxa that are either controversial or left in open nomenclature. The generic systematics of foraminifera used in this study is that of Loeblich & Tappan (1988), whereas the classification for the ostracods is based on that set forth by Hazel (1983). Specimens are deposited in the Howe collection. Department of Geology and Geophysics, Louisiana State University, Baton Rouge, Louisiana. Part 1. Foraminifera Order Foraminiferida Eichwald, 1830 Suborder Textulariina Delage & Hérouard, 1896 Superfamily Litnolacea de Blainville, 1827 Family Lituolidae de Blainville, 1827 Subfamily Ammomarginnlinfnae Podobina, 1978 G&axis Ammobaculites Cushman, 1910 Ammobaculites coprolithiformis (Schwager, 1867) PL 9, figs 17-18 1867 Haplophragmium coprolithÿbrmis Schwager: 654, pi. 34, fig. 3. 1938 Ammobaculites coprolithtformis var. sequana Mohlen 11, pi. 3, fig. 2. 1971 Ammobaculites coprolithÿormis Wemli: 310, pi. 1, fig. 16, pi. 2, figs 6-8. 1991 Haplophragmium coprolithÿormis sequanum Todria, 1991:78, pi. 36, fig. 2 . Material: Crasnicol F61808 well - 18 specimens; Caraorman West FI 1/7 - 448 specimens. Horizon: lower Oxfordian of Crasnicol F61808 well, upper Oxfordian - lower Kimmeridgian of Caraorman West FI 1/7 well. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 112 Family Nautiloculinidae, Loeblich & Tappan, 1985 Genus Nautiloculina Mohier, 1938 Nautiloculina cf. N oolithica Mohier, 1938 Pl. 9, figs 11-14 1938 Nautiloculina oolithica Mohlen 1984 Nautiloculina oolithica Bemien 514, pl. 16, figs 7-9. Material: Caraorman West FI 1/7 well - 28 specimens. Horizon: upper Oxfordian - lower Kimmeridgian of Caraorman West FI 1/7 well. Remarks: the specimens from the investigated material differ from those illustrated in previous works only in having a lesser number of chambers in the last whorl (9 in the former and 10-17 in the latter) and a lesser number of whorls (2.5 in the former and 3 in the latter). Order Foraminiferida Eichwald, 1830 Suborder Involutinina Hohenegger & Filler, 1977 Family Planispirillinldae Piller, 1978 Genus Planispirillina Bermudez, 1952 Planispirillina sp. 1 PI. 10, figs 22-24 Material: Caraorman West FI 1/7 well - 5 specimens. Horizon: middle Oxfordian to lower Kimmeridgian of Caraorman West FI 1/7 well. Description: Test planispiral, with umbilical side covered with granules distributed in a radial pattern. The dorsal side is ornamented with ridges corresponding to the sutures and radial granules. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D 00 CD Atlantic margin •g)2 of North America C/) Present C/) study (Ascoli, 1990) fom m lnifem b oiirncods ctlcarctttu hcnihic McntMXOtti hcnihic CD 8 "O NtPlnKhadna fntrcfnsti (O' SdmlrrUrtt iritM l Cpiiutmffm mtuifufnsis OiArrrrtirtrtreierbrri Fknularia fdc«dftrf/ CD liyrtmcjirtierr Inirrnymi Q. tiyirtêcwbrrr w i* (mnlmtrfHaihtaCpistomina episiomimt rtgHlariM Bpistomina çoronafa ■D CD (/) JL Fig. 7.4 Biozonation of Jurassic deposits from wells Crasnicol F61808 and Caraorman West FI 1/7, w compared to existing microfauna-based zonations. 114 Hierarchical Clustering, Method = Centroid J CW-266 CW-254B CW-263 CR-283 CW-203 CR-196 CR-210 CR-244 CR-214 CR-217 CR-267 CR-233 CR-273 CR-271 CR-227 CR-270 CR-276 CR-260 CR-269 CR-246 CR-253 CR-234 CW-227 CW-222 CW-215 CW-254 CW -244 CW-231 Fig. 7.5 Q-mode cluster analysis of samples from the Caraorman West FI 1/7 and Crasnicol F61808 wells, used to identify biofacies units. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) C/) Hierarchical Clustering, Method = Centroid inner shelf middle-outer ■D8 carbonate platform siliciclastic shelf D"" 1.4 15 0.2 0.6 22.4 E p isto m 'ma 10 4.3 12.5 S p i r illi m 5.9 5.3 10.1 L e n tic u lim 9 6.3 7.3 D is c o r b is 3. 7.6 2.7 5 Paalzowella 3 " CD 7.7 0 0 Large agglutini 0 5.9 1.6 Bathysyphon ■DCD O 11.3 11.5 3.4 S m a ll a g g lu tin a n ts Q. m ilio lid s C 16.9 22 3.8 a 16.3 24.4 3.6 Ophthalmidium 3O "O O CD Q. Fig. 7.6 R-mode cluster analysis of selected foraminifer species and groups from the Caraorman West FI 1/7 and Crasnicol F61808 wells and their average relative abundance in each biofacies. ■D CD C/) C/) CD ■ D O Q. C g Q. ■D CD C/) 3o" O CD ■D8 Species/ (O' groups Environments 3. 3 " CD inner shelf, carbonate platform ■DCD O inner shelf, Q. C siliciclastic Oa middle outer 3 ■D shelf O CD Q. "O CD Fig. 7.7 Paleobathymetric distribution of selected foraminifer species from the Upper Jurassic of the Caraorman West FI 1/ and Crasnicol F61808 wells. Shaded areas reflect average relative frequency per biofacies from fig. 7.6. (/) Cf\ CD "D O Q. C g Q. ■D CD C/) C/) CD ■D8 (O' 'y; ' 3"3. CD ■DCD O Q. C inner jaentic a [carbonate platforml siliciclastic 3O middle-outër heritic "O O CD outerneriticl Q. ■D CD (/) Fig. 7.8 Paleobathymetric distribution of selected foraminifer and ostracod species in the Oxfordian-Kimmeridgian of the Predobrogean Depression. 118 Remarks: the forms of this species are close to P. granulosa Mityanina, 1957, having the same ornamentation on the umbilical side, but differ from it by the presence of ornamentation on the dorsal side. Suborder Spirillinina Hohenegger & Piller, 1975 Family Spiriilinidae Reuss & Fritsch, 1861 Genus SpU illina Ehrenberg, 1843 S p irillin a cf. S . p o lyg yra ta Gümbel, 1862 PI. 10, figs 25-26, 29 1862 Spirillina polygyrata Gümbel; 214, pi. 4, fig. 10. 1988 Spirillina polygyrata Bielecka: 235, pi. 87, fig. 6. Material: Caraorman West FI 1/7 well - 48 specimens. Horizon: middle Oxfordian of Caraorman West FI 1/7 well. Remarks: the specimens grouped here differ from S. polygyrata as found in this section and illustrated in the literature, by having a larger initial chamber, most obvious in lateral view. These specimens might represent macrospheric forms of S. polygyrata, but their overall size is larger than the latter. S p irillin a sp. 1 PI. 11, figs 3-4 Material: Caraorman West FI 1/7 well - 7 specimens. Horizon: middle Oxfordian of Caraorman West FI 1/7 well. Description: Test planispiral, involute, with both sides slightly concave. Sutures are not visible; lateral surfaces are covered with large pores. Suborder Miliolina Delage & Herouard, 1896 Superfamily Cornnspiracea Schultze, 1854 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 119 Family Nobeculariidae Jones, 1875 Subfamily Nubecolinellmae Avnimelech & Reiss, 1954 Genus Vinelloidea Canu, 1913 Vinelloidea sp. 2 (Danitch, 1971) Pl. 11, figs 7-8 1971 Nubeculinella sp. 2 Danitch; 114, pl. 18, figs 4-6. Material: Crasnicol F61808 well - 423 specimens; Caraorman West FI 1/7 well - 9 specimens. Horizon: lower Oxfordian of Crasnicol F61808 well, middle Oxfordian to lower Kimmeridgian of Caraorman West FI 1/7 well. Family Opbthalmidiidae Wiesner, 1920 Genus Ophthalmidium Kflbler & Zwingli, 1870 Ophthalmidium compressum Barnard, Cordey & Shipp, 1981 PI. 11, figs 9-11, 13-14 1971 Spirophthabnidium bolgradensis Romanov & Danitch: 133, pi. 33, figs la, b, 2a, b, 3a, b, 4a, b, pi. 34, figs 1-3. 1981 Ophthalmidium compressum Barnard, Cordey &Shipp; 398, pi. 1, figs 25, 27, text-figs 9a, 1-10, 8. Material: Crasnicol F61808 well - 613 specimens. Horizon: lower Oxfordian of Crasnicol F61808 well. Remarks: this species was reported by Romanov & Danitch (1971) firom the lower Oxfordian of the Predobrogean Depression as Spirophthabnidium bolgradensis Ivanova & Dain, in litt. As the year of publication of the study by Ivanova & Dain is unknown and no such publication could be found, the species Spirophthabnidium bolgradensis is regarded here as a nomen nudum. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 120 Suborder Robertmina Loeblîch & Tappan, 1984 Superfamily Ceratobuliminacea Cushman, 1927 Family Epistommidae Wedekind, 1937 Subfamily Epistoinimnae Wedekind, 1937 Genus E pistonuna Terquem, 1883 Epistomina uhKgi Mjatliuk, 1953 PL 13, figs 4-6 1953 Epistomina uA/igi Mjatliuk: 219, pi. 2, fig. 5. 1954 Brotzenia parastelligera Hofken 180, text-figs 4-6. 1986 Epistomina uhligi Stam: 120, pi. 1, fig. 7-14. Material: Crasnicol F61808 well - 7 specimens; Caraorman West FI 1/7 well - 18 specimens. Horizon: lower Oxfordian of Crasnicol F61808 well, middle Oxfordian of Caraorman West FI 1/7 well Remarks: this species is interpreted in the present study in the sense of Stam (1986), who TcgaidcdEpistomina parastelligera (Hofker, 1954) as conspecific with Epistomina uhligi Mjatliuk, 1953. E p isto m in a sp. 1 PI. 13, figs 7-12 1986 Epistomina volgensis var. volgensis Stam: 122, pi. 2, figs 7-12. Material: Caraorman West FI 1/7 well - 53 specimens. Horizon: middle Oxfordian to lower Kimmeridgian of Caraorman West FI 1/7 well. Description: test planoconvex to biconvex, with the umbilical side more convex than the sutural side. Sutures flush to slightly raised, straight and directed backwards on the sutural side and slightly depressed on the umbilical side. Periphery undulate. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 121 Remarks: this species is similar to that described by Stam (1986) as Epistomina aff. E. volgensis var. volgensis Mjatliuk, 1953. The latter also has an undulated periphery, in some cases with spines. No spines are present in the investigated material, but this might be also due to poor preservation. Superfamily Discorbacea Ehrenberg, 1838 Family Placentnlinidae Kasimova, Poroshina & Geodakchan, 1980 Subfamily Ashbrookiinae, Loeblich & Tappan, 1984 Genus Paalzowella Cushman, 1933 Paalzowella feifeli (Paalzow, 1932) PI. 12, figs 33-35 1932 Trocholina feifeli Paalzow: 140, pi. 11, figs 4,6-7. 1989 Paalzowellafefeli Shipp: 255, pi. 6.4.1, figs 19-22. Material: Crasnicol F61808 well - 3 specimens; Caraorman West FI 1/7 well - 74 specimens. Horizon: lower Oxfordian of Crasnicol F61808 well, middle Oxfordian to lower Kimmeridgian of Caraorman West FI 1/7 well. Remarks: the investigated material includes forms with variable height of the trochospire, which have been assigned by some authors to various subspecies - P. feifelifeifeli (Paalzow, 1932), P. feifeli seiboldi Lutze, 1960, P. feifeli elevata (Paalzow, 1932). Low and high trochospire forms are evenly represented in the material. Family Discorbidae Ehrenberg, 1838 Genus Discorbis Lamarck, 1804 Discorbis paraspis (Schwager, 1866) PI. 12, figs 21-24 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 122 1866 Rosalina paraspis Schwager 310, fig. 16. 1953 Discorbis speciosus Dain in Mjatliuk: 43, pi. 1, fig. 2. 1971 Discorbis paraspis Wemli: 337, pi. 7, figs 1-10. 1985 Ceratolamarckina speciosa Grigelis: 144, pi. 30, figs 7a, b. 1986 Discorbis parapsis Stam: 117, pi. 6, figs 5-6. 1988 Discorbis speciosus Bielecka: 234, pi. 87, figs la, b. Material: Caraorman West FI 1/7 well - 13 specimens. Horizon: middle Oxfordian - lower Kimmeridgian of Caraorman West FI 1/7 well. Remarks: This species differs from Discorbis subspeciosus Bogdanovich & Makaijeva, 1959 in having a more elongated outline, due to the last chamber which is higher than broader. Due to the difficulQr of observing features on the umbilical side, the generic assignment may vary by author. Russian and Polish authors often refer to this species asD. speciosus. Discorbis subspeciosus Bogdanovich & Makaijeva, 1959 PI. 12, figs 28-30 1959 Discorbis subspeciosus Bogdanovich & Makaijeva: 11, text-figs 2a, b, v, 4- 5. 1960 Conorbina scutulÿbrmis Seibold & Seibold: 381, figs 8c, d. 1971 Discorbis scutuliformis Wemli: 338, pi. 6, figs 18, 21,22,24, pi. 7, figs 11- 12. 1988 Discorbis subspeciosus Bielecka: 234, pi. 87, fig. 2. Material: Caraorman West FI 1/7 well - 219 specimens. Horizon: middle Oxfordian - lower Kimmeridgian of Caraorman West FI 1/7 well. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 123 Part 2. Ostracods Class Ostracoda Latreille, 1806 Suborder Podocopina Sars, 1888 Superfamily Cytheracea Baird, 18S0 Family Bjrthocytheridae Sars, 1866 Subfamily Bythocytherinae Sars, 1866 Genus Hechticythere Grundel, 1974 Hechticythere serpentina (Anderson, 1941) PI. 5, fig. 27-28 1941 Cythereis serpentina Anderson: 375, pi. 19, fig. 12. 1966 Protocythere serpentina Barken 482, pi. 9, figs 13-18. 1978 Protocythere serpentina (Anderson, 1941) Kilenyi: 288, pi. 13, figs 4-7. 1993 Hechticythere serpentina Witte & Lissenberg: 27, pi. 6, figs. 9-13. Material: 16 carapaces, 5 valves Horizon: middle Oxfordian to lower Kiimneridgian of Caraorman West FI 1/7 well. Remarks: Some authors distinguish between the species H. serpentina, H. sigmoidea and H. bireticulata based on their secondary ornamentation, which is not visible in poorly preserved specimens such as those fi^om the Caraorman West FI 1/7 well. The specimens from the investigated material have been assigned to H. serpentina as defined by Barker (1966), that is including the other mentioned species. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8. CONCLUSIONS. JURASSIC EVOLUTION OF THE CENTRAL TETHYS: MICROFAUNAL EVIDENCE Evolutionary events and biostratigraphy Lower Jurassic Lower and middle Lias foraminifer assemblages from Romania are dominated by involutinids and nodosariids. Because most of the material is represented by carbonate rocks that are investigated in thin sections, nodosariids could seldom be identified to the species level. The involutinid group underwent a major evolutionary change at the Triassic/Jurassic boundary, when forms with undifferentiated umbilical masses (Auloconus, Aulotortus, Triasina, some species of Trocholina) became extinct. Their place was taken by forms with pillars, developed at end of the Upper Triassic (some species of Involutina and Trocholina, Semiinvoluta, and Coronipora), which thrived during the lower and middle Lias. These are well represented in the material investigated in this study. This major change is attributed to the disintegration of the Triassic carbonate platforms of the western Tethyan margin due to the rifting of the Neo-Tethys (Blau, 1991), as well as to the early Liassic transgression that limited the reefal environments to which the smooth involutinids were adapted (Zaninetti, 1976). The end of the Pliensbachian marks a major decline of the involutinids, when the genera Semiinvoluta and Coronipora become extinct This is probably due to another important reduction of the carbonate platforms during the Toarcian and the early Dogger, when terrigenous sedimentation prevailed in the western part of the Tethys. Involutina liassica is still present in the Toarcian, but after this stage the genus has a very spotty and doubtful record, in the Dogger and the Upper Cretaceous. Trocholina is the only involutinid who successfully survived after the Lower Jurassic, flourishing on the Upper Jurassic and Lower Cretaceous carbonate platforms of the Tethys area, before becoming extinct during the Upper Cretaceous. 124 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 125 The range of the species Involutina liassica in the investigated material is significantly shorter than its total known range (Sinemurian in the Eastern and Southern Carpathians and Sinemurian-Pliensbachian in the Apuseni Mountains). The present study has also identiried representatives of the genus Aulotortus (A. cf. A. friedli and A.? ex gr. sinuosus) in the upper Sinemurian, indicating that not all smooth involutinids became extinct at the end of the Triassic. The most important group among Lower Jurassic foraminifera are nodosariids, more obviously so in detached material. During the Lias, this group consistently accounts for more than two thirds of the number of species in the assemblages of the north and south Tethyan margins. In the Toarcian of the Apuseni Mountains, the nodosariids represent 75%. During this study, it was possible to calibrate microfaunal species ranges to ammonite zones in some of the sections (Bratca and, in part, Munteana). Ceratobuliminids are present in all the investigated sections of Sinemurian- Pliensbachian age, but the first assemblages dominated by this family were recorded as flood-like, stratigraphically localized occurrences, in the Toarcian of the Apuseni Mountains. Among the large agglutinated foraminifera with complex structure, only one species {Pseudocyclammina liasica) was previously reported from Romania (Popa et a i, 1982, from the Lias of the Apuseni Mountains). Concerning the Lias microfauna, the most important evolutionary event is represented by a major extinction during the early Toarcian, at the boundary of the Tenuicostaum-Serpentinus (= Falciferum) ammonite zones. This extinction is very likely related to the onset of the major early Toarcian transgression, documented worldwide, and to the existence of widespread dysaerobic environments, especially in northwestern Europe. This extinction was clearly observed in the present investigation in the Toarcian of the Apuseni Mountains, where the species Marginulina prima, Vaginulina listi, Ichtyolaria intumescens, Lenticulina speciosa, L Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 126 aragonensis, Lenticulina sp. nov. of Ruget (1985) disappear at the end of the Tenuicostatum zone. The extinction also affects ostracods, among which a major casualty consists of the healdiid group, represented in the Apuseni Mountains by Ogmoconchella adenticulata, O. aequalis, and Ogmoconcha sp. A of Boomer (1992). These forms had held a dominant position in the ostracod assemblages of the early and middle Lias. TheSerpentinus zone marks a major turnover of foraminifer assemblages. The renewed microfauna of the Apuseni Mountains includes the following species: Citharina clathrata, C. longuemari, C. colliezi, Lenticulina bochardi, L. obliqua, L deslongchampsi, L. pennensis, and L. obonensis. The most significant element of this early Toarcian renewal can be considered to be the occurrence of the genus Citharina (Ruget, 1988). The last important evolutionary event among the Lower Jurassic foraminifera is represented by the first occurrence of the species Lenticulina d'orbignyi during the middle Toarcian. In the Apuseni Mountains, this event was recorded in the present study in the Borons zone, therefore at the same stratigraphie level as in western Europe (Ruget, 1988; Copestake & Johnson, 1989). Because the Jurassic foraminifer species (and to a lesser extent the ostracods) generally have long stratigraphie ranges and display significant regional range variations, diminishing the value of interval zones, the present study used assemblage zones defined by quantitative analysis in order to achieve a biozonation of the Toarcian deposits of the Apuseni Mountains. The assemblage zones are based on both foraminifera and ostracods and include: Lenticulina aragonensis assemblage zone {Tenuicostatum ammonite zone); Citharina clathrata assemblage zone {Serpentinus and the lower part of the Bifrons zones); Lenticulina d'orbignyi assemblage zone (the upper part of the Bifrons, the Variabilis and Thouarsense ammonite zones). This biozonation is similar to that set Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 127 forth by Copestake & Johnson (1984), for the same stratigraphie interval, which indicates synchronous evolutionary events in the Apuseni Mountains and northwestern Europe. Middle Jurassic The foraminifer assemblages of the Middle Jurassic are still dominated by nodosariids, but other groups increase in diversi^ or appear for the first time during this interval. Ceratobuliminids gain in importance, and epistominids appear for the first time during the Bajocian, a stage that represents the peak of the foraminifer renewal during the Middle Jurassic (Basov, 1991). The first evolutionary occurrence of epistominids was recorded in Romania by Neagu et al. (1983) and in the present study in the upper Bajocian of the Southern Carpathians ^Epistomina regularis, E. coronata, and E. nuda). Among the nodosariids, important first evolutionary occurrences are represented byLenticulina quenstedti and L tricarinella. The first occurrence of the former displays a stronger diachronism, being questionably reported from England as early as the Toarcian (Copestake & Johnson, 1989) and without doubt from the late Aalenian (Morris & Coleman, 1989), from Central Europe beginning with the Bajocian (Wemli & Septfontaine, 1971), and from the East European Platform beginning with the early Callovian (Ascoli & Grigelis, 1993). This species is mentioned from the Bajocian of the Eastern Carpathians by Neagu etal. (1983), but was not found in the same area in the present investigation. Its first stratigraphie record within this study is from the late Bathonian of the Southern Carpathians and the Scythian Platform. The speciesLenticulina tricarinella appears in Britain during the late Bajocian (Morris & Coleman, 1989), and was found during the present investigation beginning with the late Bathonian (Southern Carpathians, Scythian Platform). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 128 The Middle Jurassic assemblages identified from Romania arc dominated by the genera Lophocythere, Pleurocythere, Palaeocytheridea, Praeschuleridea, Schuleridea (Eoschuleridea), Micropneumatocythere. Some of these taxa are inherited from the Lias {Praeschuleridea, Ektyphocythere), but most have their first evolutionary occurrence during the Bajodan {Lophocythere, Pleurocythere, Palaeocytheridea) or Bathonian {Schuleridea {Eoschuleridea)). The first occurrences of these in Romania coincide to those known worldwide. The highest diversity of the Middle Jurassic ostracod assemblages is reached in the late Bathonian, a trend also illustrated in the assemblages of this age from the Southern Carpathians and Scythian Platform. This peak in ostracod diversity occurs before the Bathonian/Callovian boundary regression, marked by a major ostracod renewal (Depeche, 1985). Upper Jurassic During the Upper Jurassic, the process of foraminifer diversification continues. The nodosariids are still the most important group, but they often do not represent the majority of the species present in the assemblages. In the Oxfordian-Kimmeridgian of the Predobrogean Depression (Scythian Platform), investigated by this study, nodosariids represent only 20% of the number of species identified. This trend illustrates one of the drawbacks of the foraminiferal zonation scheme proposed by Basov (1991) (fig. 8.1). This zonation does not account for the evolutionary changes in the composition of the Jurassic foraminifer assemblages, an important variation factor which has to be added to paleolatitude and paleobathymetry. A major change in the foraminifer assemblages of the Malm from the north Tethyan margin consists of the massive colonization of carbonate platforms by large agglutinated foraminifera with complex internal structures, whose distribution was generally restricted to the south Tethyan margin during the Lower and Middle Jurassic. The speciesAlveosepta Jaccardi is characteristic of the upper Oxfordian and the Kimmeridgian, whereas Anchispirocyclina lusitanica is widespread during the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 129 Tithonian. In Romania, the species Alveosepta jaccardi was identified in the present investigation in the upper Oxfordian -lower Kimmeridgian of the Scythian Platform and Anchispirocyclina lusitanica has been reported from the Tithonian of the Eastern Carpathians (Dragastan, 1975). The analysis of the Oxfordian-Kimmeridgian microfauna from the Predobrogean Depression, performed in the present study, identified three assemblage zones; the Ophthalmidium compressum assemblage zone (lower Oxfordian), the Spirillina andreae assemblage zone (middle Oxfordian), and the Everticyclammina virguliana assemblage zone (upper Oxfordian - lower Kimmeridgian). In the Caraorman West F 11/7 well, the species Conorboides paraspis is present throughout the entire stratigraphie column. The Paraspis total range zone of Moullade (1984) was defined as corresponding to the Oxfordian, but the total range of this species has been shown to be significantly larger (Bathonian - Kimmeridgian) by Stam (1986). Due to their restricted stratigraphie range, the species Ophthalmidium compressum (lower Oxfordian), Spirillina andreae and Patelinella cristinae (middle Oxfordian) can be used as index-fossils. The large agglutinated foraminifera identified in the present study in the upper Oxfordian-lower lümmeridgian deposits of the Predobrogean Depression, such as Alveosepta jaccardi, Everticyclammina virguliana, and Mesoendothyra izjumiana, whose occurrence is strictly linked to the presence of shallow carbonate platforms, appear beginning with the early Oxfordian. However, on the East European Platform, Crimea, Caucasus, and many areas of Central Asia they are reported only beginning with the upper Oxfordian. Planktonic foraminifera are known to have evolved at least as early as the Early Jurassic (Gorog, 1994), and although they are generally rare and show little taxonomic differentiation during the Jurassic, they have been used for biostratigraphic purposes (Ascoli & Grigelis, 1993). Representatives of this group have been Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 130 identified in the present investigation only in a short interval, in the middle Oxfordian of the Scythian Platform. The material was investigated in thin sections, which did not allow species identification and the use of these forms for biostratigraphy. Paieogeography Lower Jurassic One of the most important lines of evidence concerning the paleobiogeography of the Jurassic microfossils is provided by the distribution of the large benthic foraminifera with complex internal structures and of calcareous algae. During the Lias, large agglutinated foraminifera with complex structures are found only on the southern Tethyan margin (fig. 8.2), in areas corresponding to the present north- African coast, from Morocco to Egypt, neighboring areas of the middle East, from Israel to the Arabian Peninsula, and also including the Apulian Block (Italy and Croatia). The distribution of this foraminifer group during the early and middle Lias allowed Bassoullet et a i (1985), to define a south-Tethyan bioprovince characterized by the presence of species of the genus Orbitopsella, as well as of the species Labyrinthina recoarensis, Mayncina termieri, Haurania ex gr. amiji-deserta and Pseudocyclammina liasica. The distribution of these foraminifer species also corresponds to that of the dasycladacean alga Palaeodasycladus mediterraneus. With the exception of a few cosmopolitan species, this foraminifer was not present on the carbonate platforms of the north Tethyan margin during the Liassic. According to Bassoullet et al. (1985), this distribution might be due to a climatic incompatibility. The Liassic north Tethyan shelf was located at paleolatitudes higher than 30°N. No large benthic foraminifera with complex internal stmctures have been identified in the present investigation in Sinemurian and Pliensbachian deposits from the Apuseni Mountains, Southern Carpathians, and Eastern Carpathians, but the species Pseudocyclammina liasica was reported from the Northern Apuseni Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 131 Mountains by Popa et a i (1982). Specimens of the calcareous alga Palaeodasycladus barrabei were identified in the Pliensbachian of the Southern Carpathians This species, first described from the Lias of southern France (Lebouche & Lemoine, 1963), was also identifîed in northern Italy (Cousin & Neumann, 1971), and therefore has a cosmopolitan distribution, in contrast to P. mediterraneus, whose occurrence is restricted to the southern Tethyan margin. The complete absence of large benthic foraminifera with complex internal structures from the Liassic carbonate platforms of the Eastern and Southern Carpathians clearly indicates a north Tethyan location for the central Carpathian units during this time interval. The absence from the Apuseni Mountains of the Orbitopsella species, diagnostic for the south Tethyan province, indicates a similar position of the Tisia plate during the Lower Jurassic. The species Pseudocyclammina liasica is probably more cosmopolitan than previously assumed. This is evidenced by the widespread distribution of Pseudocyclammina during the Middle and Late Jurassic, on both Tethyan margins. However, the presence of P. liasica in the Apuseni Mountains might also point to a slightly lower paleolatitude of the Tisia plate during the Lias, in respect to the central Carpathian units. The rich involutinid microfauna identified in all Sinemurian-Pliensbachian sections holds no paleobiogeographic value, as this group is extremely cosmopolitan, being known throughout the Tethys, including the epicontinental basins of the northern and southern margins, from Eastern Canada to Papua, New Guinea. The detached microfauna (foraminifera and ostracods) from the Sinemurian-Pliensbachian of the Southern Carpathians shows strong affrnities with that of the epicontinental basins of northwest Europe. The foraminifer assemblage includes the species Ichtyolaria brizaeformis and Lingulina tenera, considered as characteristic for Boreal Lower Jurassic assemblages in Europe (Copestake & Johnson, 1989). The ostracods Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 132 Paradoxostomal pusillwn and Ogmoconcha contractula are also important components of Boreal assemblages. However, so far most of the existing micropaleontologicai studies on Jurassic detached microfauna have focused on northwestern Europe. As data concerning the siliciclastic facies of the southern Tethyan margin became available during the last decades, many species such as Lenticulina muensteri, Ichtyolaria brizaeformis, Lingulina tenera and Ogmoconcha contractula have been found in areas that belonged to the Jurassic south Tethyan margin (Baloge, 1981 - Algeria; Haig, 1979 - Papua, New Guinea; Boutakiout, 1990 - Morocco; Bartolini eta l., 1992 - Italy). The Toarcian detached microfauna of the Apuseni Mountains, investigated in this study, also displays very strong similarities with northwest European assemblages of the same age. This is obvious not as much at the level of the identified foraminifer species (most of which have been also reported from the south Tethyan shelf), but in the distribution of the flood-like occurrence of the ^ot^xmm^ex Reinholdella macfadyeni. This species, so far known only from the north Tethyan margin, strongly dominates foraminiferal assemblages around the boundary of Tenuicostatum and Serpentinus ammonite zones in the Apuseni Mountains, being closely related to the deposits formed at the onset of the early Toarcian transgression. Similar flood like occurrences of this species, at the same stratigraphie level and also in a transgressive setting, are reported from the Toarcian of England (Copestake & Johnson, 1989). Evidence for the strong north European paleobiogeographic affinities of the Lias deposits from the Apuseni Mountains is also provided by the macrofauna. A brachiopod assemblage similar to that of the Franco-Swabian basin is recorded from the Pliensbachian of the Codru nappes (Moneasa) by lanovici et al. (1976), and the Toarcian ammonite assemblages of the Bihor Autochthon are described as being of "pure NW-European type, without Phylloceratids” by Patrulius & Popa (1971). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD TYPES OF FORAMINIFER ASSEMBLAGES nCaroomian, Scythian Philform C/) C/) 0 Mntm 'I'asaui, Central High southern Middle southern Low Middle northern High northern Dobrogcan Massif palcolaiiludcs paleolatitudes paleolatitudes paleolatitudes paleolatitudes oBigar, S. Car|»thians (Icmpcmie zone) (subtropical zone) (tropical zone) (subtropical zone) (temperate zone) Vindciei, Scythian Platftmn OStningulita, E. Carpathians ■D8 ^Bratca, Apuseni Mts, B Garda Scaca, Apuseni Mts. □ Munteana, S. Carpathians Laeu Rosu, E. Carpathians Matin Bulzului, Apuseni Mts. CD Moneasa, Apuseni Mts. Nodosartidae, NodosartUlae, 3. Atmnodiscidae Nodosariidae, Epistomhddae Afwnodiscidat 3 " CD (with rare planktonics) ■DCD O Q. C a 3O "O 'plrillitddae, Nodosariidae O with abundant planktonics) CD Q. gglutinated Ibraminilem. radiolori T 3 CD C/) C/) Fig. 8.1 Distribution of Jurassic foraminifer assemblage types as a function of paleobathymetry and paleolatitude, tvith the plots of the assemblages identified by the present study (after Basov, 1991). 73 ■DCD O Q. C g Q. ■ D CD C/) C/) » JÜ « ■D8 p. 3 " CD CD ■D O Q. 3O ■O O & lliPii O c ■o CD A = Apuseni Mts. C = Central Car|»thian units F = foteland units Major faults Subduction zone (gC/) o' Active spreading ridge I j Emerged land 3 Limit between thick and thin continental crust Ut Fig. 8.2 Disttnbution of large benthic foraminifera in the Tethys area during the Pliensbachian (after Bassoullet efa/„ 1985). 135 In addition to the large benthic foraminifera and the detached microfauna, a third line of paleogeographical evidence is provided by the distribution of important lithofacies. As shown by a map of the percentage of total organic carbon (TOC) contained in Toarcian deposits of the Tethys area (fig. 8.3) by Baudin et al. (1985), which generally correlates to the distribution of dysaerobic environments, the Toarcian Anoxic Event resulted in deposition of organic-rich deposits over large areas at the level of theSerpentinus (= Falcÿérum) ammonite zone. Northwestern Europe is characterized by the most extensive and TOC-rich deposits, such as the Jet-Rock in Great Britain, Posidonienschiefer in Germany and Switzerland, Posidonia Shales in the North Sea area. Schistes Cartons in the Paris Basin. The equivalent of these deposits was identified in the present investigation in the black shales occurring in the Northern Apuseni Mountains, in the Serpentinus ammonite zone, characterized by dwarf foraminifer assemblages (<250pm) indicating dysaerobic environments. The presence of Toarcian black shales with a significant content of pyrite has been recorded before in this area (lanovici et al., 1976), but this is the first time they are regarded as the expression of the Toarcian Anoxic Event, documented on a micropaleontologicai basis. Early Toarcian organic-rich deposits occur only to a lesser extent on the south Tethyan margin. The closest black shales in such a setting occur in northern Italy. Dwarf foraminiferal assemblages have been also reported from these deposits, but they are dominated by the speciesLingulina tenera, which is absent from the assemblages of the Apuseni Mountains. The clear paleobiogeographic affinity of the Tisa plate to north Europe during the Early Jurassic indicates that if Tisia was a part of the south Paleo-Tethyan margin before the closing of this ocean, the latter event and therefore the collision of Tisia with the north Tethyan margin must have occured before the Sinemurian. The results Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 136 of the present study do therefore contradict the late Jurassic age assigned to the closing of the Paleo-Tethys (Cimmerian) ocean by Chanell & Kozur (1997). Middle Jurassic The only Middle Jurassic large benthic foraminifer species with complex internal structuress that has been identified in the present investigation in Romania is Pseudocyclammina maynci, from the late Bathonian of the Central Dobrogean Massif. This species is part of the cosmopolitan taxa group (Bassoullet et a l, 1985), being present on both Tethyan margins. Large benthic foraminifera have been also reported by Dragastan (1980), from the Bajocian {Pseudocyclammina sp.), Bathonian {Protopeneroplis striata, Haurania sp.), and Callovian-Oxfordian (Pseudocyclammina maynci, Protopeneroplis striata, Nautiloculina oolithica, and Urgonina frolojurensis) of the Persani Mountains (Central Carpathian Unit of the Eastern Carpathians). These species also belong to the cosmopolitan taxa group and do not provide accurate paleobiogeographic evidence. Among detached microfauna, the foraminifer assemblages identified in Romania are very similar to those first described from northwestern Europe. However, as in the case of the Lower Jurassic, many important Middle Jurassic foraminifer species, such asLenticulina tricarinella, L. muensteri, L. varians, L quenstedti, Citharina clathrata, Saracenaria oxfordiana, Epistomina mosquensis, Planispirillina granulosa, and Ophthalmidium strumosion, have been reported from the south-Tethyan shelf (Musacchio, 1979 - Argentina; Kalia & Chowdhury, 1983 - India; Karega, 1990 - Tanzania; Boutakiout, 1990 - Morocco). The study of Gordon (1970), was the first to emphasize the similarity between the foraminifer assemblages of the north Tethyan and south Tethyan margins, in deposits with prevailing terrigenous sedimentation, and assigned them to the "shelf assemblage group. The assemblages including large benthic foraminifers with complex internal structures or planktonic foraminifera have been included in the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 137 "Tethys" assemblage group. Kalia & Chowdhurry (1983), reporting on Middle Jurassic foraminifer assemblages from northern India, very similar to those of Europe and North America, have provided further support for the latitudinal bipolarity of Jurassic shelf foraminifera. These authors have also shown that, unlike the case of the macrofauna, it is not possible to recognize among foraminifera a separate bioprovince in the southern hemisphere (the "Ethiopian" bioprovince of Hallam, 1975). Basov (1991) has proposed a distribution chart for all Jurassic foraminifer assemblage types (fig. 8.1), which takes into account two important factors: paleolatitude and paleobathymetry. This probably represents the most complete and satisfactory zonation yet, although two other factors - the type of sedimentation and the evolutionary changes - are not fully taken into account The foraminifer assemblages analyzed in the present study have been plotted on this diagram (fig. 8.1); most of them fall within the nodosariid-epistominid and nodosariid-spirillinid groups, corresponding to the subtropical waters of the continental shelf from the northern hemisphere. Middle Jurassic ostracods provide much better paleobiogeographic evidence than foraminifera, because the former display significant provincialism. At the genus level, many taxa are common to both Tethyan margins. Important genera first described from the north European epicontinental basins, such as Micropneumatocythere, Schuleridea, Praeschuleridea, Ektyphocythere, Galliaecytheridea, Cytherella, and Cytherelloidea have been also identified on the south Tethyan margin (Basha, 1980 - Jordan; Rosenfeld et al., 1987 - Egypt; Depeche etal., 1987 - Saudi Arabia; Rafara, 1990 - Madagascar; Ballent, 1991 - Argentina). However, the two areas are quite distinct at the species level. The Middle Jurassic ostracod assemblages from Romania indicate strong affinities with the north European basins. The upper Bajocian ostracod assemblages from the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 138 Eastern Carpathians, investigated in this study, include species known from northern Europe. The genera Lophocythere and Palaeocytheridea, common in the Middle Jurassic deposits of Germany, Poland, and Ukraine, and not reported from the south Tethyan margin, are represented in the Eastern Carpathians by species new to science. The late Bathonian-early Callovian ostracod species of the Barlad Depression (Scythian Platform) and the Southern Carpathians are typical of northern Europe, being first described in basins of Poland, Ukraine, Germany, and England. At this stratigraphie level, a stronger provincialism is displayed by the assemblage identified in the Central Dobrogean Massif, which includes a species of the ostracod genus Cytherelloidea which is new to science. The upper Bathonian-lower Callovian Bositra facies (with or without dysaerobia) is widely distributed in the Carpathian and foreland units (Eastern and Southern Carpathians, Moesian Platform, Scythian Platform). This facies has a significant world-wide distribution, but it occurs on both margins of the Tethys, which does not allow it to be used for paleogeographic purposes. Upper Jurassic During the Upper Jurassic, the large agglutinated foraminifera with complex inner structure have thoroughly colonized the north Tethyan margin. The largest paleolatitudinal extent of reefal facies and of the associated large agglutinants was reached during the Kimmeridgian - slightly higher than 35“N, according to Bassoullet et al. (1985). This is explained by an increase of the temperature of surface waters (Cecca et al., 1993).. However, most of these taxa are cosmopolitan. The speciesAlveosepta jaccardi and Everticyclammina virgidiana were identified in large numbers in the present study in the upper Oxfordian - lower Kinuneridgian deposits of the Scythian Platform (Predobrogean Depression). Although these species are present on both margins of the Tethys, they are much more rare on the Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 139 Apulian block carbonate platform (Pélissié et a i, 1982). Their abundance in the deposits of the Scythian Platform is therefore indicative of north Tethyan affinities. Many of the smaller benthic foraminifera identified in the present study from the Oxfordian-Kimmeridgian of the Scythian Platform are common to both Tethyan margins. However, the species Spirillina andreae and Patellinella cristinae are so far known only from Poland and Georgia. The Predobrogean Depression has the strongest paleobiogeographic links with the Polish sector of the East European Platform, Crimea and Caucasus. The affinities with the central sector of the East European Platform (the Moscow basin) are less important, probably due to the large emerged land of the Ukrainian shield, which separated the two areas. The foraminiferal assemblage described by Barbulescu & Neagu (1970) ft-om the upper Oxfordian-lower Kimmeridgian reefal deposits of the Central Dobrogean Massif is extremely similar to that identified in the present study ftom the Predobrogean Depression, excepting for the conspicous absence of the large agglutinated froraminifera with complex structure from the former. The following large benthic foraminifera with complex structure have been reported by previous studies from Romania: - Tithonian of the Eastern Carpathians: Torinosuella peneropliformis, Rectocyclammina chouberti, Anchirospirocyclina lusitanica, Everticyclammina irregularis (Dragastan, 1975 - Bicaz Valley basin); Nautiloculina oolithica, Kumubia jurassica, Pseudocyclammina lituus, Everticyclammina virguliana, Rectocyclammina sp. (Dragastan, 1980 - Hasmas Mountains). - Tithonian of the Southern Carpathians: Pseudocyclammina sp., Everticyclammina virguliana, m d Nautiloculina oolithica (Bucur, 1977); Protopeneroplis striata and Nautiloculina oolithica (Dragastan, 1980 - Vanturarita area). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) m i ... J i l l C/) ■D8 3. 3 " CD ■DCD O Q. C a m m 3O "D O CD Q. TOARCIAN 185 Ma ■D TOTAL ORGANIC CD CARBON (% TOC) A = Apuscni Mis, C = Central Carpathian units F = foreland units C/) Major faults ,a —*• Subduction zone C/) Active spreading ridge | j Emerged land nil::::: Limit between thick and thin continental crust Fig. 8.3 Distribution of total organic carbon in the Tethys area during the Toarcian (after Baudin et al,, 1985). 141 - Tithonian of the Moesian Platform: Nautiloculina oolithica, Protopeneroplis striata , Rectocyclammina sp., Everticyclammina virguliana (Dragastan, 1986). - Oxfordian of the Northern Apuseni Mountains: Kilianina rahoensis (Dragastan et al., 1986). - Tithonian of the Northern Apuseni Mountains: Farurgonina caeliensis (Dragastan et al., 1986); Everticyclammina irregularis and Pseudocyclammina lituus (Manea & Serini, 1980); Farurgonina caeliensis, Kumubia palastiniensis, K. cf. Kvariabilis, Kilianina rahoensis, and Valvulina lungeoni (Bucur, 1988). During the Tithonian the large benthic foraminifera reached the peak of their cosmopolitanism and their assemblages are virtually identical on both Tethyan margins. The only discrimination may be based again on the that Alveosepta and Everticyclammina are rare in the Apulian block carbonate platforms. In Romania the species Everticyclammina virguliana is consistently recorded in the Eastern Carpathians, Southern Carpathians, and Moesian Platform, but is absent in the Apuseni Mountains This absence might correspond to the separation of the Tisia continental fragment from the north Tethyan margin, and its movement to the south together with the Apulian block, due to the opening of the North Apulian seaway. The earliest evidence in this respect might be represented by the presence of a brachiopod fauna of south-Tethyan affinity in the Mecsek Mountains of the Tisia plate (Voros, 1995). However, clear paleobiogeographic differences between the Apuseni Mountains on one hand, and the central Carpathian and foreland units on the other, such as the distribution of the dasycladacean algae Salpingoporella dinarica (Dragastan, personal communication), appeared only during the Barremian-Aptian interval. Paleoenvironments and sea-level variations The lack of modem analogs does not allow Jurassic microfaunal species to be used directly for paleoenvironmental reconstructions; even at the level of higher Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 142 taxonomie groups, such as the Nodosariidae family, changes in environmental distribution are known to have occurred since the Jurassic (Copestake & Johnson, 1989). The paleoenvironmental reconstructions achieved within the present study use sedimentologic data combined with the interpretation of microfaunal parameters. The microfaunal parameters taken into accoimt are the absolute abundance, diversity, heterogeneity, percentage of fragniented specimens, rate of fauna! change, presence of other fossil groups, and the mineralogy of the washed residue. Most of these parameters have been calculated for both foraminifera and ostracods, but the foraminifera data are more reliable due to the large number of specimens identified. The absolute abundance was taken into account only in some sections, where each sample consisted of a constant amount of material, and the entire residue was picked. This parameter is considered to be significant only when analyzed together with diversity. High absolute abundance coupled with high diversity, heterogeneity, and very fine grained lithology has been used to identify condensed sections corresponding to maximum flooding surfaces. Diversity has been calculated in its simplest form, as the number of species present. Increasing diversity and heterogeneity have been interpreted as corresponding to deeper waters. Heterogeneity, reflecting the evenness of the distribution of specimens among the species present in the sample, has been calculated using the Shannon-Weiner information function (Murray, 1991). The percentage of fi-agmented specimens was considered to be directly correlated with the energy levels of the environments. The rate of fauna! change (the number of last local occurrences deducted from that of first local occurrences) was regarded as indicative of biofacies changes. The other fossil groups that provided paleoenvironmental information were echinoderms and ammonites (including rhyncholites - cephalopod jaws, and onychites - belemnoid arm hooks). The former were used as an evidence of normal marine waters within the shelf, and the latter as an Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 143 indicator of increased water depth. The abundant presence of pyrite in the washed residue points to a restricted environment An other important criterion was represented by the worldwide distribution and known interpretation of facies such as the lower Toarcian black shales (Posidonienschiefem), or the upper Bathonian Bositra facies, identified in Romania. The paleoenvironments recognized in the investigated material are shown in figure 8.4. The identification of the succession of paleoenvironments allowed to describe the sequence stratigraphie framework of some of the sections (Munteana, Bratca, Strungulita, Caraorman West FI 1/7). Third order cycles were recognized in these sections, and divided into systems tracts by identifying the maximum flooding surfaces and sequence boundaries. The succession of reconstructed paleoenvironments has allowed the establishment of relative sea-level variation curves for the analyzed sections. It was not possible to construct a complete curve for the entire investigated stratigraphie interval. Detailed curves have been established for the Sinemurian-Pliensbachian of the Southern Carpathians, Toarcian of the Apuseni Mountains, and late Oxfordian - early Kimmeridgian of the Scythian Platform. Major transgressive trends were identified at the level of the late Bajocian in the Southern Carpathians and late Bathonian in the Central Dobrogean Massif, Scythian Platform, and Southern Carpathians. The resulting relative sea-level variation curves were compared to eustatic curves proposed by different authors (fig.8.5). The comparison between relative and eustatic sea-level curves is to be interpreted with caution, as it is very difficult to separate in the fortner the eustatic signal from local factors, such as tectonics and sediment input. However, in sections where the rate of rock accumulation is very small (Munteana, Bratca, Strungulita, Piatra Tasaul) it is safe to assume that the succession of paleoenvironments directly reflects eustasy. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) lllllll Munteana, S, Carpathians; Environments inner neritic middle neritic outer neritic 3o' Lacu Rosu, E, Carpathians; O Garda Seaca and Piatra Bulzului, carbonate silicic astic Apuseni Mis, platform j’ above ...... dysaerobic Stages ! wave base ■D8 Munteana, S. Carpathians O x fo rd ia n Moneasa, Apuscni Mts. C a llo v ia n [CvMvj Bratca, Apuseni Mts, 3. B a th o n ia n 3 " CD Strungulita, S, Carpathians ■DCD B a jo cia n O Q. Piatra Tasaul, C Central Dobrogean Massif Oa A a le n ia n 3 ■D Bigar, S, Carpathians O T o a rcia n m m CD m m I Vinderei, Scythian Platform Q. Pliensbachian Caraorman West FI 1/7, Scythian Platform ■D S in e m u r ia n CD Crasnicol F6I808, C/) Scythian Platform C/) Fig. 8.4 Environments identified in the investigated sections and wells. CD ■ D O Q. C g Q. ■D CD C/) Sahagian C/) Present study Hallam, 1988 Haq et a/., 198! e ta L 1996 l OOm Sp 0 CD 8 KIMMKRIDOIAN OXroRDIAN g CAIJ CD Q. TOARCIAN "O CD PLIENSBACHIAN C/) C/) oINKMURlAN y / / / / / / / f . dysncrobic environments Fig. 8.5 Sea-level variations in the investigated sections, compared to eustatic sea-level curves of different authors. 146 The sea-level changes identified in the present study in the Jurassic deposits from Romania match well the eustatic curves proposed by Hallam (1981, 1988), Vail et a i (1984), Haq et al. (1988), Sahagian et aL (1988) at the level of the late Sinemurian, early Toarcian, and middle Oxfordian - early Kinuneridgian. Differences are however present at the level of the late Bajocian, interpreted as an interval of sea-level rise in the present study, Hallam (1988), and Sahagian et al. (1996), and as an interval of comparatively low sea-level by Haq etaL (1988). The late Bathonian is also regarded as representing a sea-level rise in the present study and by Hallam (1988), but is viewed in an opposite manner by Haq et aL (1988) and Sahagian et aL (1996). Two third-order cycles were identified in the Tenuicostatum-Thouarsense ammonite zone interval of the Toarcian in the present study and by Hallam (1988), whereas three are recognized by Haq et at. (1988) for the same stratigraphie interval. Two third-order cycles were also identified in the Oxfordian-Kinuneridian of the Predobrogean Depression. Higher order sea-level cycles could be observed in the upper Oxfordian carbonate deposits of the same area. Paieobathymetric models One of the most important goals of this study was to provide future paleoenvironmental reconstructions with a powerful tool, by construction of models for the paieobathymetric distribution of the most significant species of Jurassic foraminifera and ostracods. Such paieobathymetric models were established using quantitative analysis to correlate the distribution of the investigated species with the succession of paleoenvironments previously reconstmcted using sedimentologic data and microfaunal parameters. This approach requires the investigated section to satisfy two conditions: on one hand to display a significant range of paleoenvironmental variation, and on the other to represent a time interval narrow enough not to include important evolutionary events, which would account for assemblage variations not related to Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 147 paleoenvironmental factors. Among the investigated sections, these requirements were met by the Bratca section (Toarcian of the Apuseni Mountains) and Caraorman West FI 1/7 well (Oxfordian-Kimmeridgian of the Scythian Platform). Broad biofacies units were identified using (J-mode cluster analysis, with the relative frequency of the main foraminifer components (species or groups that account for >5% of the total number of specimens) as parameters. The coefficient of correlation used (the Euclidian distance) was chosen in order to take into account the quantitative aspects of microfaunal distribution. In the case of the Bratca section, the initial division was refined to the level of biofacies subunits by using the values of the main microfaunal parameters (diversity, heterogeneity, and percentage of fragmentation) as input for Q-mode cluster analysis. R-mode cluster analysis and the averages of the relative frequency of each investigated species were used to identify the species characteristic of each biofacies subunit A method of presenting the resulting model for the Toarcian of the Apuseni Mountains is given in figure 8.6, which shows the dominant species in each environment. The principal results of the two paieobathymetric distribution models constructed in the present study for Toarcian and Oxfordian-Kimmeridgian microfaunal species can be summarized as follows, in terms of dominant species: - inner neritic, siliciclastic, high energy: Lenticulbm muensteri (Toarcian). - inner neritic, siliciclastic: Lenticulina muensteri, L. subalata, Cytherella toarcensis, Bairdiacypris rectangularis, Kinkelinella sermoisensis (Toarcian); Ophthalmidiion compressum, O. carinatum, Spirillina polygyrata, Discorbis subspeciosus, Vinelloidea sp. 1 Danitch, 1971 (Oxfordian-Kimmeridgian). - inner neritic, carbonate platform: Alveosepta jaccardi, Everticyclammina virguliana, Mesoendothyra izjumiana, Nautiloculina cf. N. oolithica (Oxfordian- Kimmeridgian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD WC/) 3o" 3 CD 8 ■D ë'3" i 3 CD "n 3.c 3 " CD ■DCD O Q. C Oa 3 ■D O INNERNEMTIC | MIDDLE NERinCl OUTCRNERmC CD Q. above wave base! dyisaerobic ■D CD L C/î C/) ______-- Fig. 8.6 Paieobathymetric distribution model for Toarcian microfauna from the Apuseni Mountains. 149 - middle neritic: Lenticulina obliqua, L varians, L. chicheryi, L muensteri, Kinkelinella sermoisensis, Ektyphocythere intrepida, Cytherella toarcensis, Bairdiacypris rectangularis (Toarcian). - middle-outer neritic: Ammobacculites coprolithiformis, Epistomina uhligi, Epistomina mosquensis, Paalzowella feÿèli, Lenticulina quenstedti, Spirillina andreae, Discorbis subspeciosus, Hechticythere serpentina (Oxfordian- Kimmeridgian). - outer neritic: Reinholdella macfadyeni, L. chicheryi, L. obonensis, L. bochardi, L. varians, Liasina lanceolata, Trachycythere tubulosa, Wellandia faveolata, Baidiacypris triangularis (Toarcian); Globuligerina sp., Conicospirillina bassiliensis, radiolarians (Oxfordian-Kimmeridgian). - outer neritic, dysaerobic: Lenticulina bochardi, L. pennensis, L. obonensis, L. lanceolata, Trachycythere tubulosa. (Toarcian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. REFERENCES Ainsworth, N. R. 1986. Toarcian and Aalenian ostracoda from the Fastnet Basin, offshore south-west Ireland. Geological Survey o f Ireland, Bulletin, 3:277-336. Arias, C. F. & Comas-Rengifo, M. J. 1992. Ostracodos del Domeriense superior y Toaiciense inferior de la Cordillera Iberica. Revista Espanola de Aficropaleontologia, 24(3): 111-155. Ascoli, P. 1990. Foraminiferal, ostracode and calpionellid zonation and correlation of 42 selected wells from the north Atlantic margin of North America. Bulletin of Canadian Petroleum Geology, 38(4): 485-492. Ascoli, P. & Grigelis, A. 1993. Zonal subdivision of the Middle Jurassic-Lower Cretaceous in Canada and Eastern Europe According to Foraminifer Evidence. Stratigrqfia. Geologicheskaia korreliatda, l(4):47-56. Atanasiu, I. & Raileanu, G. 1950. Contributiuni la cunoasterea liasicului din Muntii Haghiroas. 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Erlanger geologische Abhandlungen, 69:1-77. Wemli, I. & Septfontaine, M. 1971. Micropaleontologie comparée du Dogger du Jura meridional (France) et des Prealpes Médianes Plastiques romandes (Suisse). Eclogae Geologiae Helvetiae, 64:437-458. Wignall, P. B. 1991. Model for transgressive black shales ? Geology, 19:167-170. Wignall, P. B., Maynard, J. R. 1993. The Sequence Stratigraphy of Transgressive Black Shales. In Katz, B. J. & Pratt, L. (Eds) Source rocks in a sequence stratigraphie framework, AAPG Studies in Geology, 37:35-47. Witte, L. & Lissenberg, T. 1993. Ostracods from the Callovian to Ryazanian strata (‘Upper Jurassic’) in the Central North Sea Graben (Netherlands offshore). Mededelingen Rijks Geologische Dienst, 51: 1-69. Zaninetti, L. 1976. Les foraminiferes du Trias. Revista Italiana de Paléontologie, 82(1): 1-258, Milano. Ziegler, P. 1988. Evolution o f the Arctic-North Atlantic and the Western Tethys. American Association of Petroleum GeologistsMemoir 43: 1-197. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX A: TABLES 161 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CD ■ D O Q. C g Q. ■D CD C/) Table 1.1 Important references grouped by topic. C/) Foraminifera Ostracods Biostratigraphy Paleobiogeography ■D8 Welzel, 1968 Lord, 1978 Bartenstein & Brand, 1937 Gordon, 1970 Noriing, 1972 (S Sweden) (Great Britain) Noriing, 1972 Bassoullet e/a/., 1985 Kilenyi, 1978 Exton, 1979 (Portugal) Moullade, 1984 Basov, 1991 (Great Britain) Exton & Gradstain, 1984 Barnard era/., 1981 (England) Donze, 1985 (France) 3 Ruget, 1985 (W Europe) Depeche, 1985 (France) Copestake, 1985 Paleotectonic 3 " reconstructions CD Riegraf, 1985 (SW Germany) Knitter, 1983 (Germany) Ruget, 1988 Ainsworth, 1986 CD Copestake & Johnson, 1989 Bielecka, 1988 ■D (offshore Ireland) Burchfiel, 1980 O (Great Britain) Q. Copestake & Johnson, 1989 C Arias & Comas-Rengifo, 1992 Sandulescu, 1984 a Boutakiout, 1990 (Morocco) (Spain) O Morris & Coleman, 1989 Dercourt era/., 1986 3 Herrero, 1991 (Spain) Witte & Lissenberg, 1993 "O Shipp, 1989 Ziegler, 1988 (Netherland offshore) o Boutakiout, 1990 Paleobathymetry Schudack, 1994 Scotese, 1991 Ascoli, 1990 CD (NW Germany) Dercourt era/., 1993 Q. Todria, 1991 Brouwer, 1969 Marcoux era/,, 1993 Eustatic curves Johnson, 1976 Boomer, 1991 Picha, 1996 ■D Morris, 1982 Ascoli & Grigelis, 1993 Chanell & Kozur, 1997 CD Hallam, 1988 Stam, 1985 C/) Haq et a t; 1988 C/) Rey et a/., 1994 Sahagian et al„ 1996 8 163 Table 1.2 Foraminifer data from Bratca section A IN iTeanU TSopeati* Bafio» — 1 v m b r n « L — r B a a n a M M iiL 9 n a u u M M b n a a 4 ?SKcoikiaaL 7 1 AaaodBcs aH cn 1 Rcoglas4iinitilbfBi( 2 ItlniifiiM iiiilii ManÉtaiir 1 1 A aiH raliirt fnwiwniii 9 rimlm— M«ip.A 2 2 3 ladet. iitM iM cd foonnircia 1 X WHUmm#*. I leHyotaminwec» 4 [cfetntariaiolaa 1 rwjMii— i « t DnaUaaaodlfea 1 D a b lm m w i.A 1 nrnfilianPL X Wortwani— Mifcn 1 5 M m lnnhi fewiO Trif 2 1 N a lo a m n L I t 95 hcgdooodoaria maliinaMa 1 11 E^adoaodaaria Toiola 1 1 hcatfaaadoariaiD.A 3 Liaaaliaacamaa 2 riBtiaUMaaa 54 5 91 49 5 # ■ 32 141 « ramicallaaaiaraTrimal- 1 • 34 97 99 32 141 « 3 « LnaimliBa loain alaa m i L t 5 LcartealiaapolyioaaBBitU t 49 24 25 3 LaadraliaammalaimmaL. 1 UabalaiamiM. 13 13 219 I LeadodmaloclanBaiaL 1 1 44 L-bockanfiBKM. 3 4 35 LaadcaliaacMckonaiaL 5 2 4 49 24 L_elDCbcnria«A. 1 4 224 4 L_ckidnyiBtF. 15 L.dnckc Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 164 Table 13 Ostracod data from Bratca section T 0 A A N iy/S—ph« iTemuLl TSerpeatimn | Birims I Vtiwii» iTboiïl OMracodelua UmaconclielU adenocuuia ___ 17 _ _ _ _ ■ . ______- - . OnnocaachdU aeaalis ------— ------■ - — ------— ------OmnocoochmNL 27 . CythereitoGf. pnetoncciisis 6 5 Cvtberella louceiHis 2 ICytheicUasiL 3 1 1 CytherelkMieasiL A 1 M y c w * 1 1 FWicyDrissp. A : EtoeynritffiB I FkncnmsHiLC 5 Fkiacyprissp. D 4 106 6 5 1 6 Bairdiacveris tedmipilans U 9 7 Baiidjacypris (rianiailarit 3 TBainSaap. 4 16 5 23 LiasiiialaiiccaUla 5 Tadnrcytfaeie (nbutosa cubuL 1 9 15 riacbycythae aibolon sentina 3 2 Ektvptiacytlieie debdis 2 Ektvphocvtlieie ialRiiiiia 2 2 4 KinkeUaella aeimoiaeiKBS 2 WeUaadia raveolala 8 Procvthenira so. 3 3 lodeLO en. ( s il A 3 J 4 laddennuule ostracodes i3 64 ""M 3 9 a 18 is " 1 " " b 14 No. ar oMne. « td a m 8 5 2 6 5 3 3 5 2 0 4 No. or ostracode spcelci Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX B: MICROFOSSIL LISTS 165 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 166 Munteana section: thin sections Ammodiscus sp. "Textularia" sp. Glomospirella sp. A Glomospirella sp. Involutina liassica (Jones, 1853) Trocholina umboFrcntz&n, 1941 T. mrrij Frentzen, 1941 Aulotortus cf. A.friedli (Kristan-Tollmann, 1962) Aulotortusl ex gr. sinuosus Weynschenk, 1956 Semiinvoluta clari Kristan, 1957 S. violae Blau, 1987 S. bicarinata Blau, 1987 Coronipora austriaca Kristan, 1957 C. etrusca (Pirini, 1966) C. gusici Blau, 1987 Spirillina'l sp. Turrispirillina sp. Ophthalmidium martanum (Fannacci, 1959) O. leischneri (Kristan-Tollmann, 1962) O. carinatum (Leischner, 1961) Ophthalmidium sp. Nodosaria sp. Lenticulina sp. "Epistomina" sp. Globochaete alpina Lombard, 1937 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 167 Palaeodasycladus aff. P. barrabei Lebouché & Lemoine, 1963 detached material - samples 5/91, 14/91, 15/91. Ammodiscus sp. Involutina liassica (Jones, 1853) Spirillina d.S. polygyrata Giimbel, 1862 Ichtyolaria brizaeformis (Bomemann, 1854) Pseudonodosaria melo (Bomemann, 1854) Lingulina ex gr. tenera Bomemann, 1854 Paradoxostomal pusillwn Michelsen, 1975 Ogmoconcha contractulaTncbél, 1941 Ogmoconchella sp. Lacu Rosu section (thin sections only): "Textularia” sp. Involutina liassica (Jones, 1853) Trocholina umboFrcntz&n, 1941 Ophthalmidium sp. Lenticulina sp. "Epistomina" sp. Moneasa section (thin sections only): "Textularia" sp. Involutina liassica (Jones, 1853) Trocholina umbo Frentzen, 1941 Spirillinal sp. Turrispirillina sp. OphthalmidiianmartanumÇFzrimcci, 1959) O. "carihamm" (Leischner, 1961) Lenticulina sp. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 168 "Epistomina” sp. Garda Seaca section (thin sections only): Involutina liassica (Jones, 1853) Trocholina umbo Frentzen, 1941 Trocholina laevis Kristan, 1957 Spirillinal sp. Ophthalmidium leischneri (Kristan-Tollmann, 1962) Lenticulina sp. "Epistomina" sp. Piatra Bulzului (thin sections only): Ammodiscus sp. Involutina liassica (Jones, 1853) Lenticulina sp. Strungulita section Foraminifera: Lenticulina ex gr. muensteri (Roemer, 1839) L ovatoacuminata (Wisniowski, 1890) Planularia eugenii (Terquem, 1863) Citharina clathrata (Terquem, 1864) C longuemari (Terquem, 1863) Ophthalmidium infraoolithica (Terquem, 1870) Spirillina infima (Strickland, 1846) Paalzowella feifeli (Paalzow, 1932) Epistomina regularis Tetquem, 1883 £. coronato Terquem, 1883 E. nuda Terquem, 1883 Lenticulina sp. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 169 Eogiittulina sp. O stracods: Cytherella perennisBlaszyk, 1967 C. catenulata (Jones & Sherbom, 1888) Patellacythere paravulsa tenuis Brand, 1990 Praeschuleridea ex gr. subtrigona (Jones & Sherbom, 1888) Micropneumatocythere globosa Bate, 1864 Homocytheridea cf. H. triangulata Brand, 1990 Lophocythere sp. 1 Lophocythere sp. 2 Lophocythere sp. 3 Palaeocytheridea sp. 1 Palaeocytheridea sp. 2 Paracypris sp. Macrocypris sp. Neurocytherel sp. Oligocythereisl sp. Otoliths (fish ear bones); Otolithus (Lycopteroidarum) omatus O. tenuicostatus Bigar section: Foraminifera Haplophragmoides cf. H. cushmani Loeblich & Tappan, 1946 Trochammina canningensis Tappan, 1955 Vemeuilinoides favus (Bartenstein, 1937) Ophthalmidium strumosum (Giimbel, 1862) Palaeomiliolina czestochowiensis (Pazdro, 1959) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 170 Nodosaria metensis Çïç,içÿ\t.m, 1858) Pseudonodosaria sp. Citharina clathrata (Terquem, 1864) C/rAanna coW/ezi (Terquem, 1868) Frondicularia sp. I Dentalina brueckmanni Mjatliuk, 1959 Dentalina pseudocommunis Franke, 1936 Lingulina nodosaria 1870) Lenticulina muensteri (Roemer, 1839) L. acutiangulata (Terquem, 1864) L. tricarinella (Reuss, 1863) L. van'ûnj (Bomemann, 1854) L. mq/or (Bomemann, 1854) L. quenstedti (Gümbel, 1862) Spirillina infima (Strickland, 1846) Eoguttulina sp. Paalzowella feifeli (Paalzow, 1932) Trocholina sp. 1 Rheinholdella sp. Ostracods Cytherella perennis Blaszyk, 1967 C. cf. C. limpida Blaszyk, 1967 Cytherella sp. Cytherelloidea sp. 1 Bairdia pumicosaSh&p^zid, 1981 Bairdia sp. Schuleridea (Eoschuleridea) bathonica Bate, 1967 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 171 Rhynchoütes (cephalopod jaws) Rhynchoteuthys gibber 1907) Leptocheilus sp. Well Vinderei IP South: Foraminifera Ammobaculites agglutinons (d'Orbigny, 1846) Vemeuilinoides mauritii (Terquem, 1866) Palaeomiliolina czestochowiensis (Pazdro, 1959) Ophthalmidium strumosum (Gümbel, 1862) O. carinatum Kubler & Zwingli, 1870 Spirophthalmidium concentricum (Terquem & Berthelin, 1875) Dentalina pseudocommunis Franke, 1936 Nodosaria mutabilis Terquem, 1870 Lenticulina muensteri (Roemer, 1839) L. acutiangulata (Terquem, 1864) L. varions (Bomemann, 1854) L. quenstedti (Gümbel, 1862) L. mayor (Bomemann, 1854) L. tricarinella (Reuss, 1863) Saracenaria oxfordiana Tappan, 1958 Spirillina radiataT&tquem, 1866 S. infima (Strickland, 1846) Conicospirillina cf. C. trochoides (Berthelin, 1879) Planispirillina granulosa MiQranina, 1957 Miliospirella lithuanien Grigelis, 1958 E. nuda Terquem, 1883 Paalzowella feifeli (Paalzow, 1932) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 172 Ostracods Cytherella cf. C. limpida Blaszyk, 1967 Paracypris procera'QXdsvyV^ 1967 Bairdia sp. I Ektyphocythere aff. £1 renatae Blaszyk, 1967 E. nucleopersica Blas^k, 1967 Palaeocytheridea subtilis Permyakova, 1974 P. parabakiroviMalz, 1962 Pleurocythere favosa Triehcl, 1951 Micropneumatocythere brendae Sheppard, 1978 M. falcata Sheppard, 1978 Fuhrbergiella {Fuhrbergielld) transversiplicata Brand & Malz, 1962 Praeschuleridea subtrigona (Jones & Sherbom, 1888) Schuleridea (Eoschuleridea) bathonica Bate, 1967 Pichottia elegans Ware & Whatley, 1980 Fuhrbergiella sp. Piatra Tasaul section: Foraminifera Lenticulina muensteri (Roemer, 1839) Lenticulina sp. 1 Plcmulariabeieranaifj^TvixX, 1862) Pseudocyclammina maynci Hottinger, 1967 Nodosaria sp. Eoguttulina sp. Ostracods Cytherella cf. C. perennis Blaszyk, 1967 Cytherelloidea jugosa (Jones, 1884) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 173 Cytherelloidea sp. 1 Lophocythere carinata Blaszyk, 1967 Preaschuleridea cf. P. quadrata Bate, 1967 Darwinula sp. Well Caraorman West Fll/7: Foraminifera Reophax difflugiformisBrady, 1879 R. sterfcii Ha&usl&ty 1890 Bathysiphon sp. Rhizammina rudis Kaptarenko, 1959 Hyperammina ramosa Brady, 1879 Ammobaculites coprolithiformis (Schwager, 1867) A. agglutinons (d’Orbigny, 1846) A. fontinensis Çï&rqn&m, 1870) Ammobaculites sp. l Haplophragmoides canui Cushman, 1910 Haplophragmoides sp. 1 Trochammina squamata Jones & Parker, I860 T. cf. T. canningensis Tappan, 1955 Textularia jurassica (Gümbel, 1862) Textularia sp. 1 Vemeuilinoides minuta Said & Barakat, 1958 Dorothia Jurassica (Mitjanina, 1957) Gaudryina sherlocki Bettenstaedt, 1952 Gaudryina sp. 1 Tritaxia sp. 1 Tritaxia sp. 2 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 174 Glomospira variabilis (Kubler & Zwingli, 1870) Glomospira pusilla (Geinitz, 1848) Alveosepta jaccardi (Schrodt, 1894) Evertycyclananina virguliana (Koechlin, 1942) Mesoendothyra Kjumiana Dain, 1958 Nautiloculina cf. N. oolithica Mohler, 1938 Lenticulina quenstedti (Giimbel, 1862) L muensteri (Roemer, 1839) L. subalata (Reuss, 1854) L. varions (Bomemann, 1854) L. ectypa (Loeblich & Tappan, 1950) L. tricarinella (Reuss, 1863) mg Planularia, Falsopabmda L. beierana (Giimbel, 1862) mg Planularia L. eugenii (Terquem, 1864) mg Planularia Saracenaria oxfordiana Tappan, 1955 Saracenaria comucopiae (Schwager, 1865) Dentalina sp. Citharina clathrata (Terquem, 1863) Citharina colliezi (Terquem, 1868) Marginulina cf. M. scapa Lalicker, 1950 Nodosaria hortensisTerqaem, 1866 Nodosaria lagenoides'Wismowsld, 1890 Nodosaria sp. 1 Pseudonodosaria sp. 1 Eoguttulina oolithica (Terquem, 1864) Frondicularia oolithica Terquem, 1870 Ramulina spandeli Paalzow, 1917 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 175 Discorbis paraspis (SchwagcT, 1866) D. subspeciosus Bogdanovich & Makaqeva, 1959 Conorboides marginata Lloyd, 1962 Spirillina orbicula Terquem & Berthelin, 1875 S. polygyrata Gümbel, 1862 S. cL S. polygyrata Gümbel, 1862 S. elongata Bielecka & Pozarysky, 1954 S. tenuissima Gümbel, 1862 S. andreae Bielecka, I960 Spirillina sp. 1 Planispirillina granulosa Mityanina, 1957 Planispirillina sp. I Paalzowella feffeli (Paalzow, 1932) Paalzowella turbinella (Gümbel, 1862) Patelinella cristinae Bielecka, 1960 Trocholina solecensis Bielecka & Pozaryski, 1954 r. nodulosa Seibold, 1960 Epistomina uhligi Mjatliuk, 1953 Epistomina mosquensis Ublig, 1883 Epistomina sp. 1 Conicospirillina basiliensis Mohler, 1938 Conicospirillina cf. C. testata Grigelis, 1985 Vinelloidea labirinthica Danitcb, 1971 Vinelloidea sp. 2 (Danitcb, 1971) Sigmoilina deprimataDanitch, 1971 Ophthalmidium carinatum Kubler & Zwingli, 1870 Quinqiieloculina jurassica Bielecka & Styk, 1966 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 176 Globuligerina sp. Ostracods Polycope riegrqfi Brand, 1990 Hechticythere serpentina (Anderson, 1941) Galliaecytheridea dorsetensis Christensen & Kilenyi, 1971 Galliaecytheridea sp. Mandelstamia (Mandelstamia) rectilinea Malz, 1958 Mandelstamia sp. Nophrecythere cruciata alata (Whatley, 1970) Enp/eara efeonorae Wilkinson, 1987 Bairdia sp. Procytherura sp. Crasnicol F61808: Foraminifera Rhizammina rudis Kaptarenko, 1959 Bathysiphon sp. Ammobaculites coprolithiformis (Schwager, 1867) A. agglutinons {d'Otbigay, 1846) Haplophragmoides canui Cushman, 1910 Trochammina squamata Jones & Parker, 1860 Glomospira variabilis (Kubler & Zwingli, 1870) Glomospira pusilla {Gemitz, 1848) Gaudryina sherlocki Bettenstaedt, 1952 Lenticulina quenstedti (Giimbel, 1862) L muensteri (Roemer, 1839) L. var/anr (Bomemann, 1854) L ectypa (Loeblich & Tappan, 1950) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 177 L beierana (Gümbel, 1862) mg Planularia Saracenaria oxfordiana T^pan, 1955 Ophthalmidium compressum Bamard, Cordey & Shipp, 1981 Vinelloidea sp. 2 ^anitch, 1971) Quinqueloculina Jurassica Bielecka & Styk, 1966 Eoguttulina oolithica (Terquem, 1864) Ramulina spandeli Paalzow, 1917 Conorboides marginata Lloyd, 1962 Spirillina orbicula Terquem & Berthelin, 1875 S. polygyrata Gümbel, 1862 S. elongata Bielecka & Pozarysky, 1954 S. tenuissima Gümbel, 1862 Spirillina sp. 1 Conicospirillina basiliensis Mohler, 1938 Trocholina solecensis Bielecka & Pozaryski, 1954 Paalzowella feifeli (Paalzow, 1932) Epistomina uhligi Mjatliuk, 1953 Pseudolamarckina rjasanensis (Uhlig, 1883) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX C: MICROFOSSIL PLATES 178 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 179 PLATE 1 Scale bar =100 [un. All specimens from Bratca section. Fig. 1. Thurammina subfavosa Franke, 1936; 183/91, Bifrons zone. Fig. 2. Ammodiscus siliceus (Terquem, 1862); 189/91, Tenuicostatum zone. Fig. 3. Reophax difflugiformis Brady, 1879; 185/91. Bifrons zone. Fig. 4. Haplophragmoides kingakensis Tappan, 1955; 185/91, Bifrons zone. Fig. 5. Ammobaculites fontinensis Terquem, 1870; 185/91, Bi^ronj zone. Fig. 6. Trochammina sp. A; 185/91, Bifrons zone. Fig. 7. Ichtyolaria intumescens (Bomemann, 1854); 189/91, Tenuicostaum zone. Fig. 8. Ichtyolaria sulcata (Bomemann, 1854); 188/91, ISerpentinus zone. Fig. 9. Dentalina nodigera Terquem & Berthelin, 1875; 185/91, Bifrons zone. Fig. 10. Dentalina cf. D. terquemi d’Orbigny, 1849; 184/91, Bifrons zone. Fig. 11. Dentalina sp. A; 185/91, Bifrons zone. Fig. 12. Nodosaria annulifera Ftcnizen, 1941; 188/91, ISerpentinus zone. Fig. 13. Nodosaria fontinensis Terquem, 1870; 185/91, Bifrons zone. Fig. 14. Pseudonodosaria multicostata (Bomemann, 1854); 185/91, Bifrons zone. Fig. 15. Nodosaria sp. A; 189/91, Tenuicostatum zone. Fig. 16. Pseudonodosaria vulgata (Bomemann, 1854); 185/91, Bifrons zone. Fig. 17. Pseudonodosaria sp. A; 184/91, B ifrons zone. Fig. 18. Lingulina cemua (Berthelin, 1879); 185/91, Bifrons zone Fig. 19. Lenticulina muensteri (Roemer, 1839) mg Lenticulina; 182/91, Bifrons zone. Fig. 20. Lenticulina acutiangulata (Terquem, 1864) mg Lenticulina; 182/91, Bifrons zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 180 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ISI PLATE 2 Scale bar = 100 |im. All specimens from Bratca section. Fig. 1. Lenticulina subalata (Reuss, 1854) mg Lenticulina', 182/91, Bifrons zone. Fig. 2. Lenticulina polygonata (Franke, 1936) rag Lenticulina; 188/91, 'ISerpentinus zone. Fig. 3. Lenticulina bochardi (Terquem, 1863) mg Lenticulina; l^5/9\, Bifrons zone. Fig. 4. Lenticulina bochardi (Terquem, 1863) mg Marginulinopsis; 185/91, Bifrons zone. ^\g. 5. Lenticulina chicheryi^diydsd., \9^1 mg Lenticulina; 188/91, ISerpentinus zone. Fig. 6. Lenticulina chicheryi Fayaid, 1947 mg Astacolus; 186/91, ISerpentinus zone. Fig. 7. Lenticulina chicheryi Payard, 1947 mg Planularia; 185/91, Bifrons zone. Fig. 8. Lenticulina chicheryi Payard, 1947 mg Afarginulinopsis;lS4l9l, Bifrons zone. Fig. 9. Lenticulina chicheryi Payard, 1947 mg Falsopalmula; 184/91, Bifrons zone. Fig. 10. Lenticulina varions (Bomemann, 1854) mg Lenticulina; 189/91, Tenuicostatum zone. Fig. II. Lenticulina d'orbignyi (Roemer, 1839) mg Lenticulina; 181/91, Bifrons zone. Fig. 12. Lenticulina d'orbignyi (Roemer, 1839) mg Marginulinopsis; 181/91, Bifrons zone. Fig. 13. Lenticulina cf. L. pennensis Cubaynes & Ruget, 1983 mg Marginulinopsis; 188/91, ISerpentinus zone. Figs 14, \S, Lenticulina obonensis Ruget, 1982 mg Planularia. 14. 188/91, ISerpentinus zone. 15. 188/91, ISerpentinus zone. Fig. 16. Lenticulina obliqua (Terquem, 1864) mg Astacolus; 185/91, Bifrons zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 182 Fig. 17. Lenticulina obliqua (Terquem, 1864) mg Planularia; 185/91, Bifrons zone. Fig. 18. Lenticulina obliqua (Terquem, 1864) mg Falsopalmula; 185/91, Bifrons zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 183 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 184 PLATE 3 Scale bar = 100 All specimens from Bratca section. Fig. 1. Lenticulina deslongchampsi (Terquem, 1864) mg Falsopalmula; 188/91, ISerpentinus zone. Fig. 2. Lenticulina cordtformis (Terquem, 1863) mg Planularia; 184/91, Bifrons zone. Figs 3,4. Lenticulina aragonensis Ruget, 1982 mg Saracenella. 3. 189/91, Tenuicostatum zone. 4. 189/91, Tenuicostatum zone. Fig. 5. Lenticulina speciosa Terquem, 1858 vag Marginulinopsis; 189/91, Tenuicostatum zone. Figs 6, 7. Lenticulina sp. nov. Ruget, 1985 mg Planularia. 6. 189/91, Tenuicostatum zone. 7. 189/91, Tenuicostatum zone. Figs 8, 9. Lenticulina sp. A mg Planularia. 8. 185/91, Bifrons zone. 9. 185/91, Bifrons zone. Fig. 10. Lenticulina sp. B mg Lenticulina; 184/91, Bifrons zone. Fig. 11. Lenticulina sp. B mg Marginulinopsis; 184/91, Bifrons zone. Fig. 12. Lenticulina sp. C mg Marginulinopsis; 182/91, Bifrons zone. Fig. 13, 15. Lenticulina sp. D mg Marginulinopsis. 13. 189/91, Tenuicostatum zone. 15. 189/91, Tenuicostatum zone. Fig. 14. Marginulina prima d’Orbigny, 1849; 189/91, Tenuicostatum zone. Figs 16, VJ. M arginulina sp. A. 16. 184/91, B ifrons zone. 17. 184/91, B ifrons zone. Fig. 18. Citharina colliezi (Terquem, 1866); 185/91, Bifrons zone. Fig. 19. Citharina clathrata (Terquem, 1863); 184/91, Bifrons zone. Fig. 20. Citharina longuemari (Terquem, 1863); 183/91, Bifrons zone. Fig. 21. Vaginulina listi Bomemann, 1854; 189/91, Tenuicostatum zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 185 I /\ I . 1 # 4 \:% ■; ifVM2 Iff] 13 -^14 '' _ SH lz:i7 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 186 PLATE 4 Scale bar = 100 pm. All specimens from Bratca section. Fig. 1. Eoguttulina liassica (Strickland, 1846); 185/91, B ^ o n s zone. Figs 2,3. Reinholdella macfadyeni (Ten Dam, 1947). 2. sutural view, 188/91, ISerpentinus zone. 3. lateral view, 188/91, ISerpentinus zone. Fig. 4. Indeterminate foraminifer A; 185/91, Bÿrons zone. Fig. 5. Cytherella cf. C. praetoarcensis Boomer, 1991; right valve, external, 188/91, ISerpentinus zone. Fig. 6. Cytherella toarcensis Bizon, 1960; carapace, left lateral, 181/91, Bifrons zone. Fig. 7. Cytherelloidea sp. A; carapace, left lateral, 182/91, Bifrons zone. Fig. 8. Bairdiacypris triangularis Ainsworth, 1986; carapace, left lateral, 188/91, ISerpentinus zone. Figs 9,10. Baidiacypris rectangularis Ainsworth, 1986. 9. carapace, right lateral, 184/91, Bifrons zone. 10. carapace, left lateral, 184/91, Bifrons zone. Fig. 11. Paracypris sp. A; carapace, right lateral, 188/91, ISerpentinus zone. Fig. 12. Paracypris sp. B; right valve, lateral, 184/91, Bifrons zone. Fig. 13. Paracypris sp. C; carapace, left lateral, 171/91, Thouarsense zone. Fig. 14. Paracypris ? sp. D; carapace, left lateral, 185/91, Bifrons zone. Fig. 15. Liasina lanceolata (Apostolescu, 1959); carapace, right lateral, 188/91, 'ISerpentinus zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 187 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 188 PLATE 5 Scale bar = 100 jim. All specimens from Bratca section. Fig. 1. Procytherura sp.; carapace, left lateral, 181/91, Bÿrons zone. Fig. 2. Wellandia faveolata Bate & Coleman, 1975; carapace, left lateral, 185/91, Bifrons zone. Fig. 3. Kinkelinella sermoisensis (Apostolescu, 1959); carapace, right lateral, 182/91, Bifrons zone. Fig. 4. Ektyphocythere debilis Bate & Coleman, 1975; carapace, left lateral, 183/91, Bifrons zone. Fig. 5. Ektyphocythere intrepida Bate & Coleman, 1975; carapace, left lateral, 185/91, Bifrons zone. Fig. 6. Trachycythere tubulosa tubulosa Triebel & Klinger, 1959; carapace, left lateral, 187/91, ISerpentinus zona. Fig. 7. Trachycythere tubulosa seratina Triebel & Klinger, 1959; carapace, right lateral, 188/91, ISerpentinus zone. Fig. 8. Ogmoconchella aequalis Herrig, 1969; juvenile, carapace, right lateral, 189/91, Tenuicostatum zone. Fig. 9. Ogmoconcha sp. A Boomer, 1992; carapace, left lateral, 189/91, Tenuicostatum zone. Fig. 10. Ogmoconchella adenticulata (Pietrzenuk, 1961); carapace, right lateral, 189/91, Tenuicostatum zone. Fig. 11, 12. Indet. Gen. 1 sp. A. 11. carapace, left lateral, 185/91, B ifrons zone. 12. carapace, right lateral, 185/91, Bifrons zone. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. IS9 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 190 PLATE 6 Scale bar = 100 jim Fig. 1. Trocholina umbo Frentzen, 1941. Axial section. Garda Seaca, sample 154. Fig. 2. Involutina ex gr. liassica (Jones, 1853). Equatorial section. Lacu Rosu, sample 1. Fig. 3. Involutina liassica (Jones, 1853). Transversal section. Munteana, sample 8. Fig. 4. Involutina liassica (Jones, 1853). Transversal section. Piatra Bulzului, sample 15. Fig. 5. Trocholina umbo Frentzen, 1941. Axial section. Munteana, sample 8. Fig. 6. Involutina ex gr. liassica (Jones, 1853). Transversal section. Moneasa, sample 5. Fig. 7. Aulotortus cf. A .friedli (Kristan-Tollmann, 1962). Equatorial section. Munteana, sample 8. Fig. 8. Trocholina turris Frentzen, 1941. Transversal section. Munteana, sample 18. Fig. 9. Trocholina laevis Kristan, 1957. Transversal section. Garda Seaca, sample 154. Fig. 10. Aulotortus cf. A .friedli (Kristan-Tollmann, 1962). Axial section. Munteana, sample 319. Fig. II. Semiinvoluta violae Blau, 1987. Transversal section. Munteana, sample 7. Fig. 12. Semiinvoluta violae Blau, 1987. Axial section. Munteana, sample D. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 191 ■ Æ à % Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 192 PLATE 7 Scale bar = 100 |xm Fig. 1. Aulotortus! ex gr. sinuosus Weynschenk, 1956. Transversal section. Munteana, sample 305. Fig. 2. Spirillinal sp. Axial section, megalospheric form. Munteana, sample 11. Fig. 3. Globochaete alpina Lombard, 1937. Munteana, sample 8. Fig. 4. Coronipora austriaca Kristan, 1957. Axial section. Munteana, sample 18. Fig. 5. Coronipora gusici Blau, 1987. Axial section. Munteana, sample 7. Fig. 6. Coronipora etrusca (Pirini, 1966). Axial section. Munteana, sample 11. Fig. 7. Semiinvoluta bicarinata Blau, 1987. Munteana, sample D. Fig. 8. Semiinvoluta clari Kristan, 1957. Munteana, sample D. Fig. 9. Spirillinal sp. Axial section, megalosheric form. Munteana, sample 306. Fig. 10. Spirillinal sp. Transversal section, microsheric form. Munteana, sample 18. Fig. 11. Spirillinal sp. Equatorial section, megalospheric form. Munteana, sample 11. Fig. 12. Turrispirillina sp. Transversal section. Munteana, sample 7. Fig. 13. Ophthalmidium carinatum (Leischner, 1961). Transversal section. Moneasa, sample 5. Fig. 14. Ophthalmidium martanum (Farinacci, 1959). Transversal section. Munteana, sample 8. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 193 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 194 PLATE 8 Scale bar = 100 {im Fig. 1. Ophthalmidium leischneri (Kristan-Tollmann, 1962). Longitudinal section. Munteana, sample 12. Fig. 2. Ophthalmidium leischneri (Kristan-Tollmann, 1962). Transversal section. Munteana, sample 11. Fig. 3. Ophthalmidium martanum (Farinacci, 1959). Transversal section. Munteana, sample 8. Fig. 4. Ophthalmidium carinatum (Leischner, 1961). Transversal section. Munteana, sample 11. Fig. 5 Glomospirella sp. A. Munteana, sample 11. Fig. 6. ""Textularia" sp. Munteana, sample D. Fig. 7. Glomospirella sp. A. Munteana, sample 11. Fig. 8. Glomospirella sp. A. Munteana, sample F. Fig. 9. "'^Reinholdella" sp. Transversal section. Garda Seaca, sample 155. Fig. 10. “Marginulina” sp. Longitudinal section. Piatra Bulzului, sample 15. Fig. 11. Palaeodasycladus aff. P. barrabei Lebouché & Lemoine, 1963. Munteana, sample E. Fig. 12. Glomospirella sp. Munteana, sample 306. Fig. 13. “Reinholdella" sp. Equatorial section. Garda Seaca, sample 155. Fig. 14. “‘Lenticulina" sp. Garda Seaca, sample 177. Fig. 15. Echinoid spine and indeterminate nodosariid. Munteana, sample 8. Fig. 16. ‘"Nodosaria" sp. Longitudinal section. Munteana, sample 8. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 195 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 196 PLA TE 9 Scale bar = 100 Ail specimens from Caraorman West FI 1/7 well. Fig. 1. Bathysiphon sp. Sample CW-263 (middle Oxfordian). Fig. 2. Rhizammina rudis Kaptarenko, 1959. Sample CW-263 (middle Oxfordian). Fig. 3. Hyperammina ramosa Brady, 1879. Sample CW-231 (middle Oxfordian). Fig. 4. Glomospira pusilla (Geinitz, 1848). Sample CW-227 (upper Oxfordian- lower Kimmeridgian). Fig. S. Glomospira variabilis (Kubler & Zwingli, 1870). Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Fig. 6. Reophax difflug^ormis Brady, 1879. Sample CW-203 (lower Kimmeridgian). Fig. 7. Reophax sterkii Haeusler, 1890. Sample CW-231 (middle Oxfordian). Figs 8, 9. Haplophragmoides canui Cushman, 1910. 8. Sample CW-231 (middle Oxfordian). 9. Sample CW-231 (middle Oxfordian), transmitted light in imersion. Fig. 10. Haplophragmoides sp. 1. Sample CW-244 (middle Oxfordian). Figs 11-14. Nautiloculina cf. N. oolithica Mohler, 1938.11, 14 Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 12. Sample CW-222 (upper Oxfordian-lower Kimmeridgian). 13. Sample CW-227 (upper Oxfordian- lower Kimmeridgian), equatorial oriented Ain section. Fig. 15. Ammobaculites fontinensis (Terquem, 1870). Sample CW-231 (middle Oxfordian). Fig. 16. Ammobaculites agglutinons id'O doi^y, 1846). Sample CW-231 (middle Oxfordian). Fig. 17, IS. Ammobaculites coprolithiformis (Schwager, 1867). Sample CW-244 (middle Oxfordian). Figs 19, 2H. Ammobaculites sp. 1.19. Sample CW-203 (lower Kimmeridgian). 20. Sample CW-203 (lower Kimmeridgian), transmitted light in imersion. Figs 21-23. Mesoendothyra izjumiarm Dain, 1958. 21. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 22. Sample CW-222 (upper Oxfordian- lower Kimmeridgian). 23. Sample CW-222 (upper Oxfordian-lower Kimmeridgian), equatorial oriented Ain section. Figs 24-28. Evertycyclammina virguliana (Koechlin, 1942). 24. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 25. Sample CW-227 (upper Oxfordian-lower Kimmeridgian), equatorial oriented Ain section. 26. Sample CW-227 (upper OxforAan-lower Kimmeridgian). 27. Sample CW-227 (upper Oxfordian-lower Kimmeridgian), equatorial oriented Ain section. 28. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 197 Sample CW-222 (upper Oxfordian-lower Kimmeridgian), transmitted light in imersion. Figs 29, 37. Alveosepta jaccardi (Schrodt, 1894). 29. Sample CW-224 (upper Oxfordian-lower Kimmeridgian), transversal random thin section. 37. Sample CW-224 (upper Oxfordian-lower Kimmeridgian), equatorial random thin section. Fig. 30. Trochammina squamata Jones & Parker, 1860. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Fig. 31. Trochammina cf. T. canningensis Tappan, 1955. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Fig. 32, 33. Vemeuilinoides minuta Said & Barakat, 1958. 32. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 33. Sample CW-231 (middle Oxfordian). Figs 34, 35. Tritaxia sp. 1. Sample CW-244 (middle Oxfordian). Fig. 36. Dorothia jurassica (Mitjanina, 1957). Sample CW-244 (middle Oxfordian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 198 i " . t â '' m Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 199 PLATE 10 Scale bar = 100 urn. All specimens from Caraorman West FI 1/7 well. Fig. 1. Tritaxia sp. 2. Sample CW-244 (middle Oxfordian). Fig. 2. Dorothia jurassica (MiQ'anina, 1957). Sample CW-227 (upper Oxfordian- lower Kimmeridgian). Fig. 3,11. Gaudryina sp. 1. 3. Sample CW-231 (middle Oxfordian). 11. Sample CW-244 (middle Oxfordian). Fig. 4,10. Textularia jurassica (Gümbel, 1862). Sample CW-263 (middle Oxfordian). Fig. 5. Textularia sp. 1. Sample CW-215 (upper Oxfordian-lower Kimmeridgian). Figs 6-9. Gaudryina sherlocki Bettenstaedt, 1952.6. Sample CW-222 (upper Oxfordian-lower Kimmeridgian). 7,9. Sample CW-227 (upper Oxfordian- lower Kimmeridgian), transmitted light in imersion. 8. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Figs 12-13. Trocholina solecensis Bielecka & Pozaryski, 1954.12. Umbilical view, sample CW-231 (middle Oxfordian). 13. Dorsal view, sample CW-231 (mid^e Oxfordian). Fig. 14. T nodulosa Seibold, 1960. Lateral view, sample CW-222 (upper Oxfordian-lower Kimmeridgian). Figs 15,18-19. Conicospirillina cf. C. testata Grigelis, 1985.15. Dorsal view, sample CW-227 (upper Oxfordian-lower Kimmeridgian). 18. Umbilical view, sample CW-231 (middle Oxfordian). 19. Lateral view, sample CW- 227 (upper Oxfordian-lower Kimmeridgian). Figs. 16-17, 20. Conicospirillina basiliensis Mohler, 1938.16. Umbilical view, sample CW-231 (middle Oxfordian). 17. Spiral view, transmitted light in imersion, sample CW-231 (middle Oxfordian). 20. Dorsal view, sample CW- 231 (middle Oxfordian). Fig. 21. Planispirillina granulosa Mityanina, 1957. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Figs 22-24. Planispirillina sp. 1.22. Dorsal view, sample CW-203 (lower Kimmeridgian). 23. Umbilical view, sample CW-215 (upper Oxfordian- lower Kimmeridgian). 24. Lateral view, sample CW-244 (middle Oxfordian). Figs 25-26, 29. Spirillina cf. & polygyrata Gümbel, 1862. 25. Lateral view, sample CW-231 (middle Oxfordian). 26. Sutural view, sample CW-231 (middle Oxfordian). 29. Sutural view, transmitted light in imersion, sample CW-231 (middle Oxfordian). Figs 27-28, 30. Spirillina polygyrata Gümbel, 1862. 27. Lateral view, sample CW-227 (upper Oxfbrdian-lower Kimmeridgian). 28. Sutural view, sample Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 200 CW-231 (middle Oxfordian). 30. Sutural view, transmitted light in imersion, sample CW-231 (middle Oxfordian). Figs 31-33. Spirillina andreae Bielecka, 1960.31. Lateral view, sample CW-244 (middle Oxfordian). 32. Sutural view, sample CW-231 (middle Oxfordian). 33. Sutural view, transmitted light in imersion, sample CW-231 (middle Oxfordian). Fig. 34. Spirillina sp. I. Sample CW-231 (middle Oxfordian). Fig. 35. Spirillina articula Terquem & Berthelin, 1875. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 201 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 202 PLATE 11 Scale bar = 100 |im. All specimens from Caraorman West FI 1/7 well, except when indicated otherwise. Fig. 1. Spirillina tenuissima Gümbel, 1862. Sample CW-231 (middle Oxfordian). Fig. 2. Spirillina elongata Bielecka & Pozarysky, 1954. Sample CW-231 (middle Oxfordian). Figs 3-4. Spirillina sp. 1. Sample CW-231 (middle Oxfordian). Figs 5-6. Vinelloidea labirinthica Danitch, 1971.5. Sample CW-244 (middle Oxfordian). 6. Sample CW-266 (middle Oxfordian). Fig. 7. Vinelloidea sp. 2 (Danitch, 1971). Sample CW-254B (middle Oxfordian). Fig. 8. Vinelloidea sp. Sample CW-244 (middle Oxfordian). Figs 9-11, 13-14. Ophthalmidium compressum Barnard, Cordey & Shipp, 1981. 9-11,14. Transmitted light in imersion, Caraorman F61808 well, sample CR-273 (lower Oxfordian). 13. Caraorman F61808 well, sample CR-253 (lower Oxfordian). Fig. 12. Ophthalmidium carinatum Kubler & Zwingli, 1870. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Figs 15-16. Quinqueloculina jurassica Bielecka & Styk, 1966.15. Sample CW- 227 (upper Oxfordian-lower Kimmeridgian). 16. Transmitted light in imersion, sample CW-205 (lower Kimmeridgian). Fig. 17. Sigmoilina deprimata Danitch, 1971. Sample CW-231 (middle Oxfordian). Fig. IS. Nodosaria lagenoides Wisniowsld, 1890. Sample CW-231 (middle Oxfordian). Fig. 19. Nodosaria sp. 1. Sample CW-231 (middle Oxfordian). Fig. 20. Pseudonodosaria sp. 1. Sample CW-244 (middle Oxfordian). Fig. 21. Nodosaria hortensis Terquem, 1866. Sample CW-231 (middle Oxfordian). Figs 22-23. Lenticulina quenstedti (Gümbel, 1862) mg Lenticulina. 22. Sample CW-231 (middle Oxfordian). 23. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Fig. 24. Lenticulina muensteri (Roemer, 1839) mg Lenticulina. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Fig. 25. Lenticulina subalata (Reuss, 1854) mg Lenticulina. Sample CW-254 (middle Oxfordian). Figs 26-27. Lenticulina varions (Bomemann, 1854) mg Lenticulina. Sample CW- 23 1 (middle Oxfordian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 203 Figs 28-29. Lenticulina varians (Bomemann, 1854) mg Marginulinopsis. Sample CW-231 (middle Oxfordian). Fig. 30. Lenticulina ectypa (Loeblich & Tappan, 1950) mg Lenticulina. Sample CW-231 (middle Oxfordian). Fig. 31. Lenticulina tricarmella (Reuss, 1863) mg Falsopalmula. Sample CW-203 (lower Kimmeridgian). Fig. 32. Ramulina spandeli Paalzow, 1917. Sample CW-215 (upper Oxfordian- lower Kimmeridgian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 204 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 205 PLATE 12 Scale bar = 100 |im. Ail specimens from Caraorman West FI 1/7 well. Fig. 1. Lenticulina tricarmella (Reuss, 1863) mg Planularia. Sample CW-231 (middle Oxfordian). Fig. 2-3. Lenticulina beierana (Gümbel, 1862) mg Planularia. Sample CW-231 (middle Oxfordian). Fig. 4. Lenticulina eugenii (Terquem, 1864) mg Planularia. Sample CW-231 (middle Oxfordian). Fig. S. Saracenaria comucopiae (Schwager, 1865). Sample CW-231 (middle Oxfordian). Fig. 6. Saracenaria oxfordiana Tappan, 1955. Sample CW-231 (middle Oxfordian). Figs 7-9. Lenticulinal sp. 1.7. Sutural view, sample CW-231 (middle Oxfordian). 8. Sutural view, transmitted light in imersion, sample CW-231 (middle Oxfordian). 9. Lateral view, sample CW-231 (middle Oxfordian). Figs. 10-11. Citharina clathrata (Terquem, 1863). 10. Sample CW-227 (upj«r Oxfordian-lower Kimmeridgian). 11. Sample CW-231 (middle Oxfordian). Fig. 12. Citharina colliezi (Terquem, 1868). Sample CW-231 (middle Oxfordian). Fig. 13. Marginulina cf. M. scapa Lalicker, 1950. Sample CW-231 (middle Oxfordian). Figs 14-15. Eoguttulina oolithica (Terquem, 1864). Sample CW-231 (middle Oxfordian). Figs 16-18. Frondicularia oolithica Terquem, 1870.16. Sample CW-231 (middle Oxfordian). 17. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 18. Transmitted light in imersion, sample CW-227 (upper Oxfordian-lower Kinuneridgian). Figs 19-20. Conorboides marginata Lloyd, 1962. Sample CW-215 (upper Oxfordian-lower Kimmeridgian). 19. Dorsal view. 20. Umbilical view. Figs 21-24. Discorbis paraspis (Schwager, 1866). Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 21. Dorsal view. 22. Umbilical view. 23. Umbilical view, transmitted light in imersion. 24. Dorsal view, transmitted light in imersion. Figs 25-27. Paalzowella turbinella (Gümbel, 1862. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 25. Umbilical view. 26. Lateral view. 27. Dorsal view. Figs 28-30. Discorbis subspeciosus Bogdanovich & Makaijeva, 1959. Sample CW-231 (middle Oxfordian). 28. Lateral view. 29. Dorsal view. 30. Umbilical view. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 206 Figs 31-32. Patelinella cristinae Bielecka. I960. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Figs 33-35. Paalzowella feifeli (Paalzow, 1932). 33, 35. Sample CW-231 (middle Oxfordian). 34. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 207 sa Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 208 PLATE 13 Scale bar = 100 pm. All specimens from Caraorman West FI 1/7 well, except when indicated otherwise. Figs 1-2. Epistomina mosquensis Uhlig, 1883. Sample CW-254 (middle Oxfordian). 1. Sutural view. 2. Umbilical view. Figs 3-6. Epistomina uhligi Mjatliuk, 1953. Sample CW-254 (middle Oxfordian). 3. Umbilical view. 4, 5. Sutural view. 6. Lateral view. Figs 7-12. Epistomina sp. 1.7. Sutural view, sample CW-227 (upper Oxfordian- lower Kimmeridgian). 8. Lateral view, sample CW-227 (upper Oxfordian- lower Kimmeridgian). 9. Umbilical view, sample CW-244 (middle Oxfordian). 10. Sutural view, transmitted light in imersion, sample CW-227 (upper Oxfbrdian-lower Kimmeridgian). 11. Umbilical view, transmitted light in imersion, sample CW-227 (upper Oxfbrdian-lower Kimmeridgian). 12. Lateral view, sample CW-244 (middle Oxfordian). Fig. 13. Globuligerina sp. Sample CW-236 (middle Oxfordian). Fig. 14. Polycope riegrqfi Brand, 1990. Right valve, external. Sample CW-231 (middle Oxfordian). Fig. 15. Procytherura sp. Carapace, left lateral. Sample CW-215 (upper Oxfbrdian- lower Kimmeridgian). Fig. 16. Eripleura eleanorae Wilkinson, 1987. Right valve, external. Sample CW- 231 (middle Oxfordian). Fig. 17. Paracypris sp. Carapace, right lateral. Sample CW-227 (upper Oxfbrdian- lower Kimmeridgian). Fig. 18. Paracypris sp. 2. Carapace, left lateral. Sample CW-266 (middle Oxfordian). Fig. 19. Paracypris sp. 1. Carapace, right lateral. Sample CW-231 (middle Oxfordian). Fig. 20. Paracypris sp. 3. Carapace, left lateral. Sample CW-231 (middle Oxfordian). Fig. 21. Paracypris sp. 4. Carapace, left lateral. Sample CW-231 (middle Oxfordian). Fig. 22. Bairdia sp. Right valve, external. Sample CW-254 (middle Oxfordian). Fig. 23. Mandelstamia sp. Carapace, left lateral. Sample CW-227 (upper Oxfordian-lower Kimmeridgian). Fig. 24. Mandelstamia (Mandelstamia) rectilinea Malz, 1958. Right valve, external. Sample CW-244 (middle Oxfordian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 209 Figs 25-26. Nophrecythere cruciata alata (Whatley, 1970). Sample CW-227 (upper Oxfordian-lower Kimmeridgian). 25. Left valve, extenal. 26. Right valve, external. Figs. 27-28. Hechticythere serpentina (Anderson, 1941). Sample CW-227 (upper Oxfbrdian-lower Kimmeridgian). 27. Right valve, external. 28. Left valve, external. Figs 29-30. Lophocythere sp. 1. Strangulita section, sample 1 (upper Bajocian). 29. Right valve, external. 30. Carapace, right lateral. Fig. 31. Lophocythere sp. 3. Carapace, right lateral. Strungulita section, sample 1 (upper Bajocian). Fig. 32. Lophocythere sp. 2. Carapace, left lateral. Strungulita section, sample 1 (upper Bajocian). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. no Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. VITA Andrei Tudoran was bom July 20,1963, the son of Constantin and Valentina Tudoran, in Bucharest, Romania. Andrei graduated from Ion L. Caragiale High School in June, 1981. He received his master of science degree in Geology from the University of Bucharest in June, 1987. He worked for the Videle Oil Production Company in Videle, Romania, and as a Associate Researcher with the Geological Institute of Romania from September of 1987 to May of 1990. Andrei was gainfully employed at “Prospectiuni” S.A. (formerly known as the Geological and Geophysical Prospectings Company of Romania) in Bucharest, Romania, from June, 1990 to August, 1992, at which time he began graduate work towards the doctor of philosophy degree at Louisiana State University in Baton Rouge. During the summers of 1993, 1994, and 1995 he worked as a summer intern geologist for Amoco Production Company. During the summer of 1996, he worked as a micropaleontologist for the Coastal Studies Institute of Louisiana State University. Andrei will begin work for Exxon Exploration Company in June of 1997. 211 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. DOCTORAL EXAMINATION AND DISSERTATION REPORT Candidates Andrei Tudoran Major Field: Geology Title of Diaaertation: Biostratigraphlc and Paleoenvlronmental Significance of Jurassic tflcrofosslls from Romania Approved: n Mjrifeai andMajor of Graduate School EXAMINING COMMITTEE: Date of Examination: April 2, 1997 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.