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Martin I Simpson - One of the best experts on this subject based on the ideXlab platform.
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observations on the lithostratigraphy and ammonite succession of the Aptian lower cretaceous lower greensand of chale bay isle of wight uk
Cretaceous Research, 1998Co-Authors: Raymond Casey, Mark H Bayliss, Martin I SimpsonAbstract:A revised lithostratigraphy is given for parts of the Atherfield Clay and Ferruginous Sands Formations (Lower-Upper Aptian) of the Lower Greensand Group of the standard section in Chale Bay, Isle of Wight, retaining in essence the classic nomenclature of Fitton. Changes in zonal and subzonal boundaries are proposed on the basis of new collections of ammonites obtainedin situ. The Upper Lobster Beds Member of the Atherfield Clay is detached from the Subzone ofDeshayesites callidiscusand placed in a separate Subzone ofDeshayesites annelidusat the top of the Zone ofD. forbesi. The influx ofMegatyloceras, Cheloniceras, PseudosaynellaandSinzoviaat this level has palaeogeographic implications, pointing to the opening of a marine link with the Paris Basin and confirming the Upper Lobster Beds as a transgressive horizon. The upper part of the Scaphites Beds Member of the Ferruginous Sands, previously included in thedeshayseiZone, is transferred to the Subzone ofDufrenoyia transitoria, at the base of the Zone ofTropaeum(T.)bowerbanki, on the strength of the occurrence therein of species ofTropaeumandDufrenoyia.Tropaeumis not present below thebowerbankiZone as now defined; its primitive ancyloceratoid (hooked) forms such asT. (T.)hillsiihave limited biochronological value, persisting alongside the criocone (spiral) species of thebowerbankiZone and giving rise to a local horizon ofT. (T.)pseudophillsiat the bottom of the Upper Crioceras Beds (basal Upper Aptian). A more precise delimitation of the Walpen Clay & Sands from the Upper Crioceras Beds is made and the junction of these two members of the Ferruginous Sands is reaffirmed as the Lower/Upper Aptian boundary, coinciding with the junction of the Zones ofT. (T.)bowerbankiandEpicheloniceras martiniodes. Bed-by-bed collecting across the boundary shows thatEpichelonicerascan no longer be taken as the prime biostratigraphical marker for the base of the Upper Aptian; greater significance is given to the extinction ofDufrenoyia. The sources of the genusVectisitesand some species ofAmmonitocerasandCaspianites, hitherto fixed only vaguely in the column, are pinpointed in themartinioidesZone. The horizon ofTropaeum(T.)drewiis confirmed as high in thebowerbankiZone (meyendorffiSubzone) and the validity of a ‘drewiZone’ at the base of the German Upper Aptian (=base of Middle Aptian, Kemper, 1995) is questioned. In a review of the Lower/Upper Aptian boundary, it is suggested that the German stratum be called the Horizon ofCicatrites?tenuinodosusand placed tentatively at the top of the Lower Aptian. These and other changes in ammonite nomenclature are explained in the systematic notes.
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observations on the lithostratigraphy and ammonite succession of the Aptian lower cretaceous lower greensand of chale bay isle of wight uk
Cretaceous Research, 1998Co-Authors: Raymond Casey, Mark H Bayliss, Martin I SimpsonAbstract:Abstract A revised lithostratigraphy is given for parts of the Atherfield Clay and Ferruginous Sands Formations (Lower-Upper Aptian) of the Lower Greensand Group of the standard section in Chale Bay, Isle of Wight, retaining in essence the classic nomenclature of Fitton. Changes in zonal and subzonal boundaries are proposed on the basis of new collections of ammonites obtainedin situ. The Upper Lobster Beds Member of the Atherfield Clay is detached from the Subzone ofDeshayesites callidiscusand placed in a separate Subzone ofDeshayesites annelidusat the top of the Zone ofD. forbesi. The influx ofMegatyloceras, Cheloniceras, PseudosaynellaandSinzoviaat this level has palaeogeographic implications, pointing to the opening of a marine link with the Paris Basin and confirming the Upper Lobster Beds as a transgressive horizon. The upper part of the Scaphites Beds Member of the Ferruginous Sands, previously included in thedeshayseiZone, is transferred to the Subzone ofDufrenoyia transitoria, at the base of the Zone ofTropaeum(T.)bowerbanki, on the strength of the occurrence therein of species ofTropaeumandDufrenoyia.Tropaeumis not present below thebowerbankiZone as now defined; its primitive ancyloceratoid (hooked) forms such asT. (T.)hillsiihave limited biochronological value, persisting alongside the criocone (spiral) species of thebowerbankiZone and giving rise to a local horizon ofT. (T.)pseudophillsiat the bottom of the Upper Crioceras Beds (basal Upper Aptian). A more precise delimitation of the Walpen Clay & Sands from the Upper Crioceras Beds is made and the junction of these two members of the Ferruginous Sands is reaffirmed as the Lower/Upper Aptian boundary, coinciding with the junction of the Zones ofT. (T.)bowerbankiandEpicheloniceras martiniodes. Bed-by-bed collecting across the boundary shows thatEpichelonicerascan no longer be taken as the prime biostratigraphical marker for the base of the Upper Aptian; greater significance is given to the extinction ofDufrenoyia. The sources of the genusVectisitesand some species ofAmmonitocerasandCaspianites, hitherto fixed only vaguely in the column, are pinpointed in themartinioidesZone. The horizon ofTropaeum(T.)drewiis confirmed as high in thebowerbankiZone (meyendorffiSubzone) and the validity of a ‘drewiZone’ at the base of the German Upper Aptian (=base of Middle Aptian, Kemper, 1995) is questioned. In a review of the Lower/Upper Aptian boundary, it is suggested that the German stratum be called the Horizon ofCicatrites?tenuinodosusand placed tentatively at the top of the Lower Aptian. These and other changes in ammonite nomenclature are explained in the systematic notes.
J E A Marshall - One of the best experts on this subject based on the ideXlab platform.
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cretaceous hauterivian cenomanian palaeoceanographic conditions in southeastern tethys matruh basin egypt implications for the cretaceous climate of northeastern gondwana
Cretaceous Research, 2020Co-Authors: Amr S Deaf, Ian C Harding, J E A MarshallAbstract:Abstract Quantitative palynological, sedimentological, and geophysical data analyses of the Cretaceous Abu Tunis 1X well from the Matruh Basin, northwestern Egypt indicate deposition of four major alternating regressive–transgressive successions. Sedimentation was largely affected by the Tethyan 2nd order sea level changes, with minor overprints by regional tectonics. The Lower Cretaceous part of the succession shows regressive sequences of deltafront to delta-top (upper Hauterivian–lowermost upper Barremian), delta channel (upper Aptian–middle Albian), and distal deltaic (upper Albian) settings that were interrupted by transgressive inner–proximal middle shelf deposits (uppermost Barremian–middle Aptian). These sediment packages correspond to Tethyan sea level fall from the late Hauterivian to late Barremian, and to the early–middle Aptian long-term sea level high stand. The Tethyan late Aptian–middle Albian long-term (2nd order) sea level rise was masked by regional late Aptian–Albian uplift, which affected deposition of the later regressive sequence. The Cenomanian shows a change in depositional setting from a proximal inner shelf (lower Cenomanian) to a middle shelf setting (middle–upper Cenomanian), corresponding to the Tethyan long-term latest early–late Cenomanian sea level rise. We demonstrate that northeastern Gondwana (Egypt) experienced different climatic conditions from other parts of the Northern Gondwana Phytogeographic Province. The climate in Egypt shifted from less warm and more humid conditions of the Hauterivian–early Barremian to a warmer and drier climate during the late Barremian–middle Aptian, although never becoming as dry as western Northern Gondwana. Warmer and more humid conditions were reestablished during the late Aptian and became even more accentuated during the Albian–Cenomanian, in contrast to the warm and much drier climate of Northern Gondwana at that time. Turonian climatic conditions may have been less humid as a result of the breakup of the Western Gondwanan supercontinent and the northeasterly drift of the African continent. The climatic conditions experienced in northeastern Gondwana developed through the early-mid Cretaceous as a result of changes in palaeolatitudinal position, variations in sea level, and shifts in the Intertropical Convergence Zone, which drove fluctuations between periods of warm humid and warm dry conditions.
Jens O Herrle - One of the best experts on this subject based on the ideXlab platform.
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high resolution carbon isotope records of the Aptian to lower albian from se france and the mazagan plateau dsdp site 545 a stratigraphic tool for paleoceanographic and paleobiologic reconstruction
Earth and Planetary Science Letters, 2004Co-Authors: Jens O Herrle, Peter Kosler, Oliver Friedrich, Helmut Erlenkeuser, Christoph HemlebenAbstract:High-resolution carbon isotope stratigraphy is established for the Aptian to Lower Albian of the Vocontian Basin (SE France), and correlated to the carbon isotope record of the Mazagan Plateau (DSDP Site 545). The carbon isotope stratigraphy of the Vocontian Basin is proposed as a standard reference curve for the Aptian to Lower Albian, due to the completeness and high temporal resolution of the stratigraphic succession, the good biostratigraphical time control, and the frequent occurrence of regional to global black shale horizons including Oceanic Anoxic Events 1a (OAE 1a) of the Lower Aptian and OAE 1b of the Lower Albian. The carbon isotope record appears better suited for long-distance short-term correlation of different marine and terrestrial environments than biostratigraphy because of the synchroneity of carbon isotope signals in a range of sediment types. However, the combination of both biostratigraphy and carbon isotope stratigraphy provides an effective tool to reconstruct biotic change and paleoceanography, and to correlate regional to global black shale horizons in different marine environments. This combined approach allows us to ascertain the synchroneities or diachroneities of first and last appearances of biostratigraphic marker species. Based on the demonstrated diachroneity of important biostratigraphic markers of the Aptian/Albian boundary, the globally observed break point between the end of the uppermost Aptian positive carbon isotope excursion and the onset of the pronounced negative shift of δ13C values, is an alternative criterion. The distinctive structure and amplitudes of the carbon isotope record are observed in both the inorganic and organic carbon and can therefore be recognized in all marine and terrestrial environments of the Aptian to Lower Albian.
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calcareous nannofossils from the Aptian lower albian of southeast france palaeoecological and biostratigraphic implications
Cretaceous Research, 2003Co-Authors: Jens O HerrleAbstract:Abstract The Aptian–lower Albian succession of the Vocontian Basin (SE France) consists of marine hemipelagic sediments including several black shale horizons. The latter are partly of regional and partly of global distribution. This sedimentary succession records the nannoplankton evolution of the Aptian–early Albian interval and thus provides an excellent opportunity to calibrate the calcareous nannofossil record with Tethyan ammonite and planktic foraminiferal biostratigraphy. The calcareous nannofossil biostratigraphy presented in this paper supports previous zonations, but it also provides a much higher resolution and thus improves the correlation of different black shale horizons on a supraregional scale. Up to 23 major (supraregionally significant) and minor (regionally significant) first and last occurrences of calcareous nannofossil taxa are recognized. Nannoconid abundances decrease rapidly in the upper Lower Aptian (nannoconid crisis I, NCI) and in the middle Upper Aptian (nannoconid crisis II, NCII). Both decreases correlate with carbonate–platform drowning events. The upper Lower Aptian interval above the NCI is characterized by high abundances of large specimens of Assipetra infracretacea and Rucinolithus terebrodentarius probably of supraregional significance. The uppermost Aptian–Lower Albian is characterized by high abundances of the calcareous nannoplankton taxon Repagulum parvidentatum, reflecting boreal influence on the Tethyan Realm. This suggests a temporary decrease in surface-water temperatures in the Vocontian Basin.
Raymond Casey - One of the best experts on this subject based on the ideXlab platform.
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observations on the lithostratigraphy and ammonite succession of the Aptian lower cretaceous lower greensand of chale bay isle of wight uk
Cretaceous Research, 1998Co-Authors: Raymond Casey, Mark H Bayliss, Martin I SimpsonAbstract:A revised lithostratigraphy is given for parts of the Atherfield Clay and Ferruginous Sands Formations (Lower-Upper Aptian) of the Lower Greensand Group of the standard section in Chale Bay, Isle of Wight, retaining in essence the classic nomenclature of Fitton. Changes in zonal and subzonal boundaries are proposed on the basis of new collections of ammonites obtainedin situ. The Upper Lobster Beds Member of the Atherfield Clay is detached from the Subzone ofDeshayesites callidiscusand placed in a separate Subzone ofDeshayesites annelidusat the top of the Zone ofD. forbesi. The influx ofMegatyloceras, Cheloniceras, PseudosaynellaandSinzoviaat this level has palaeogeographic implications, pointing to the opening of a marine link with the Paris Basin and confirming the Upper Lobster Beds as a transgressive horizon. The upper part of the Scaphites Beds Member of the Ferruginous Sands, previously included in thedeshayseiZone, is transferred to the Subzone ofDufrenoyia transitoria, at the base of the Zone ofTropaeum(T.)bowerbanki, on the strength of the occurrence therein of species ofTropaeumandDufrenoyia.Tropaeumis not present below thebowerbankiZone as now defined; its primitive ancyloceratoid (hooked) forms such asT. (T.)hillsiihave limited biochronological value, persisting alongside the criocone (spiral) species of thebowerbankiZone and giving rise to a local horizon ofT. (T.)pseudophillsiat the bottom of the Upper Crioceras Beds (basal Upper Aptian). A more precise delimitation of the Walpen Clay & Sands from the Upper Crioceras Beds is made and the junction of these two members of the Ferruginous Sands is reaffirmed as the Lower/Upper Aptian boundary, coinciding with the junction of the Zones ofT. (T.)bowerbankiandEpicheloniceras martiniodes. Bed-by-bed collecting across the boundary shows thatEpichelonicerascan no longer be taken as the prime biostratigraphical marker for the base of the Upper Aptian; greater significance is given to the extinction ofDufrenoyia. The sources of the genusVectisitesand some species ofAmmonitocerasandCaspianites, hitherto fixed only vaguely in the column, are pinpointed in themartinioidesZone. The horizon ofTropaeum(T.)drewiis confirmed as high in thebowerbankiZone (meyendorffiSubzone) and the validity of a ‘drewiZone’ at the base of the German Upper Aptian (=base of Middle Aptian, Kemper, 1995) is questioned. In a review of the Lower/Upper Aptian boundary, it is suggested that the German stratum be called the Horizon ofCicatrites?tenuinodosusand placed tentatively at the top of the Lower Aptian. These and other changes in ammonite nomenclature are explained in the systematic notes.
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observations on the lithostratigraphy and ammonite succession of the Aptian lower cretaceous lower greensand of chale bay isle of wight uk
Cretaceous Research, 1998Co-Authors: Raymond Casey, Mark H Bayliss, Martin I SimpsonAbstract:Abstract A revised lithostratigraphy is given for parts of the Atherfield Clay and Ferruginous Sands Formations (Lower-Upper Aptian) of the Lower Greensand Group of the standard section in Chale Bay, Isle of Wight, retaining in essence the classic nomenclature of Fitton. Changes in zonal and subzonal boundaries are proposed on the basis of new collections of ammonites obtainedin situ. The Upper Lobster Beds Member of the Atherfield Clay is detached from the Subzone ofDeshayesites callidiscusand placed in a separate Subzone ofDeshayesites annelidusat the top of the Zone ofD. forbesi. The influx ofMegatyloceras, Cheloniceras, PseudosaynellaandSinzoviaat this level has palaeogeographic implications, pointing to the opening of a marine link with the Paris Basin and confirming the Upper Lobster Beds as a transgressive horizon. The upper part of the Scaphites Beds Member of the Ferruginous Sands, previously included in thedeshayseiZone, is transferred to the Subzone ofDufrenoyia transitoria, at the base of the Zone ofTropaeum(T.)bowerbanki, on the strength of the occurrence therein of species ofTropaeumandDufrenoyia.Tropaeumis not present below thebowerbankiZone as now defined; its primitive ancyloceratoid (hooked) forms such asT. (T.)hillsiihave limited biochronological value, persisting alongside the criocone (spiral) species of thebowerbankiZone and giving rise to a local horizon ofT. (T.)pseudophillsiat the bottom of the Upper Crioceras Beds (basal Upper Aptian). A more precise delimitation of the Walpen Clay & Sands from the Upper Crioceras Beds is made and the junction of these two members of the Ferruginous Sands is reaffirmed as the Lower/Upper Aptian boundary, coinciding with the junction of the Zones ofT. (T.)bowerbankiandEpicheloniceras martiniodes. Bed-by-bed collecting across the boundary shows thatEpichelonicerascan no longer be taken as the prime biostratigraphical marker for the base of the Upper Aptian; greater significance is given to the extinction ofDufrenoyia. The sources of the genusVectisitesand some species ofAmmonitocerasandCaspianites, hitherto fixed only vaguely in the column, are pinpointed in themartinioidesZone. The horizon ofTropaeum(T.)drewiis confirmed as high in thebowerbankiZone (meyendorffiSubzone) and the validity of a ‘drewiZone’ at the base of the German Upper Aptian (=base of Middle Aptian, Kemper, 1995) is questioned. In a review of the Lower/Upper Aptian boundary, it is suggested that the German stratum be called the Horizon ofCicatrites?tenuinodosusand placed tentatively at the top of the Lower Aptian. These and other changes in ammonite nomenclature are explained in the systematic notes.
Peter P Safronov - One of the best experts on this subject based on the ideXlab platform.
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the stable o and c isotope record of fossils from the upper barremian lower albian of the caucasus palaeoenvironmental implications
Cretaceous Research, 2017Co-Authors: Yuri D Zakharov, Olga P Smyshlyaeva, Mikheil V Kakabadze, Mevlud Z Sharikadze, Evgenij S Sobolev, Peter P SafronovAbstract:Abstract Late Barremian to early Albian palaeotemperatures have been determined through oxygen isotope analyses of well-preserved brachiopod, bivalve, gastropod and ammonite shells, and belemnite rostra from the Caucasus. Results from calcitic invertebrate skeletal elements from the upper Barremian Sartousiana, Securiformis and Waagenoides zones indicate palaeotemperatures of 19.2, 12.0–17.1 and 11.3–14.3 °C, respectively. In contrast, early Aptian fossils of the Weissi and Deshayesi zones reveal significantly higher palaeotemperatures (20.5–22.3 and 17.1 °C, respectively), than those obtained from brachiopod shells of the Securiformis Zone. Isotopic palaeotemperature data are not available for the Furcata Zone in the Caucasus. The warmest conditions in our study interval developed during the late Aptian Melchioris-Abichi Chrone according to data on bivalves, gastropods and the ammonite Parahoplites (20.8–27.1 °C) and the Subnodosocostatum Chrone (?25.3 °C), on the basis of a shell of the oyster Amphidonte . However, the potential influence of minor freshwater incursions into the upper epipelagic zone in which Amphidonte lived, as well as the predominance of ammonites that preferred cool conditions in the Subnodosocostatum Zone, leads to an alternative interpretation in which cooling initiated at the beginning of the late Aptian. There remains considerable uncertainty in the interpretation of δ 18 O values in fossils from the Subnodosocostatum Zone but it is possible that one or two cooling events interrupted the warmest conditions during the late Aptian. The highest δ 13 C values derived from fossils found in the Subnodosocostatun Zone (up to 8.3 and 3.9‰ for shallow-water bivalves and deeper-dwelling belemnite taxa, respectively) have been linked to an episode of late Aptian volcanic activity. On the basis of our stable oxygen isotope record, two ethological groups can be recognised among Aptian ammonites from the Caucasus: cool and thermophilic dwellers. All Early Cretaceous belemnites from this area seem to have had a preference for cool-water conditions.
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late barremian early Aptian climate of the northern middle latitudes stable isotope evidence from bivalve and cephalopod molluscs of the russian platform
Cretaceous Research, 2013Co-Authors: Yuri D Zakharov, Helmut Weissert, Eugenij Y Baraboshkin, Irina A Michailova, Olga P Smyshlyaeva, Peter P SafronovAbstract:Abstract Palaeotemperatures during the late Barremian–early Aptian (Early Cretaceous) on the Russian Platform have been determined on the basis of oxygen isotope analysis of aragonitic bivalve molluscan and ammonoid shells and belemnite rostra with well-preserved microstructure from the Ulyanovsk area. Those obtained from the planispiral and heteromorph ammonoid shells from the lower Aptian Volgensis–Schilovkensis, Deshayesi–Tuberculatum, and Deshayesi–Renauxianum zones range from 26.7 to 33.2 °C, from 29.2 to 33.1 °C, and from 27.0 to 29.5 °C, respectively. A heteromorph Helicancylus ? cf. philadelphius shell from the uppermost lower Aptian Bowerbanki Zone was secreted in highest temperature conditions (32.8–35.2 °C). In contrast, upper Barremian molluscs (bivalve Cyprina sp. and belemnite Oxyteuthis sp.) of the Ulyanovsk area show significantly lower palaeotemperatures: 16.9–18.5 °C and 7.9–17.8 °C, respectively, which is in accordance with known palaeogeographic and palaeobotanical evidences, showing that a distinct climatic optimum seems to have occurred during the late early Aptian, when warm Tethyan water penetrated into the basin. Marked changes in calculated growth temperatures for investigated molluscs from the Russian Platform were most likely connected with both the general warming trend during the late Barremian–early Aptian and local palaeonvironmental conditions. New data from the Bowerbanki Zone of the Russian Platform provide evidence on existence of the positive carbon isotope anomaly (2.4–6‰) at the end of the lower Aptian. There were apparently the three positive C-isotope anomalies during the late Barremian–early Aptian. The onset of mid early Aptian Oceanic Anoxic Event (OAE) 1a seems to coincide with both the beginning of significant warm conditions (followed by short-term cooling) and the abrupt decline in heavy carbon isotope concentrations in marine carbonates, which partly were the likely consequences of the intensive release of CO 2 (biased by volcanic activity) and/or dissociation of methane gas hydrate.
