The Upper Cretaceous successions of Wadi Umm-Khayshar,southern Galala Plateau,North Eastern Desert,Egypt,are composed of highly diversified faunas and subdivided from base to top into the Galala(Middle-Late Cenomanian...The Upper Cretaceous successions of Wadi Umm-Khayshar,southern Galala Plateau,North Eastern Desert,Egypt,are composed of highly diversified faunas and subdivided from base to top into the Galala(Middle-Late Cenomanian),Maghra El Hadida(Latest Cenomanian-Late Turonian),Matulla(Coniacian-Santonian),and Sudr(Campanian-Maastrichtian)formations.Five ammonite biozones are recorded in the studied section:Neolobites vibrayeanus,Vascoceras cauvini(late Cenomanian),Vascoceras proprium,Choffaticeras segne,and Coilopoceras requienianum(Turonian)zones.The paleoenvironments of the Upper Cretaceous succession are interpreted based on detailed study and microfacies analysis that reflect a deposition in a homoclinal ramp platform ranging from intertidal to deep subtidal.The paleoecology of the Cenomanian-Turonian succession in the studied section is explained based on a detailed study of macrofaunal associations and sedimentary facies.Quantitative analysis(Q-mode cluster analysis,using the Raup-Crick Paired group method)of 1029 macrobenthic specimens,including 45 species of mollusks and echinoids yielded five macrofaunal associations(A-E)that are described and interpreted as remnants of communities.The nektonic elements are represented by 235 cephalopod specimens of 20 species;heatmap cluster analyses show the distribution of these specimens during the Upper Cenomanian-Turonian stages.Environmental parameters(substrate consistency,rate of sedimentation,water energy,surface-water productivity,and oxygen availability)controlled the distribution of the studied macrofauna.The five associations are divided into two major groups:low-stress associations(A,B,C,and D),and a highstress association(E).The low stress associations are recorded from two different habitats:(1)a high-energy,firm substrate habitat,dominated by epifaunal bivalves,large epifaunal gastropods and a regular echinoid;(2)a low-energy,soft substrate habitat dominated by infaunal bivalves and echinoids.The high stress association is dominated by only two species and recorded from a high-energy shoal environment during a regression phase.A detailed study of macrobenthos and cephalopods provides a good paleoecological understanding of Cenomanian-Turonian succession in the Wadi Umm-Khayshar section.展开更多
Following votes by the Barremian Working Group,the International Subcommission on Cretaceous Stratigraphy and the International Commission on Stratigraphy,the Executive Committee of the International Union of Geologic...Following votes by the Barremian Working Group,the International Subcommission on Cretaceous Stratigraphy and the International Commission on Stratigraphy,the Executive Committee of the International Union of Geological Sciences unanimously approved in March 2023 the Global Stratotype Section and Point(GSSP)for the Barremian Stage(Lower Cretaceous).The base of the Barremian Stage is defined at the base of bed 171 of the Río Argos section,near Caravaca(SE Spain)and correlated by the first appearance of the ammonite species Taveraidiscus hugii.This event falls within the NC5C calcareous nannofossil Subzone,the Lilliputianella semielongata planktonic foraminiferal Zone,and the Dorothia ouachensis benthic foraminiferal Zone.It roughly coincides with the beginning of a slightly negative trend interval in theδ^(13)C curve.Indirect calibration to the magnetostratigraphic scale suggests that the boundary falls in the lowermost part of polarity chron M3r.According to the astrochronological analysis,a time interval of 0.74 myr separates the beginning of the late Hauterivian Faraoni Episode from the base of the Barremian,which is dated at 125.77 MA.展开更多
The 'Falang Formation' of western Guizhou was previously called the 'Halobia Bed' and considered to be I .adinian in age. It was subdivided upward into the Zhuganpo, Laishike and Longchang members base...The 'Falang Formation' of western Guizhou was previously called the 'Halobia Bed' and considered to be I .adinian in age. It was subdivided upward into the Zhuganpo, Laishike and Longchang members based on ammonites and the Trachyceras multitubertulatum Zone of the Longchang Member was put in the Lower Carnian. Here in the present paper, 4 genera and 9 species of ammonites and 1 nautiloid genus and species collected from the upper part of the 'Falang Formation' (i.e. the Wayao Formation used in this paper, equivalent to the Laishike Member from Guanling and Zhenfeng counties are described. The geological and geographical distribution of these cephalopods, as well as the co-existing conodonts, put the Wayao Formation to the late early Carnmian.展开更多
Defining the Jurassic-Cretaceous boundary is a controversy in stratigraphic study of the world. It has been widely accepted that this boundary can be defined at the bottom of Berriasian in Tetbys, with the appearance ...Defining the Jurassic-Cretaceous boundary is a controversy in stratigraphic study of the world. It has been widely accepted that this boundary can be defined at the bottom of Berriasian in Tetbys, with the appearance of the ammonite Berriasellajacobi dating to ca. 145 Ma. However, it is difficult for the widespread terrestrial deposits in China to correlate with the international standard of marine facies. The Somanakamura Group in Japan is represented by a succession of marinecontinental transitional strata. It provides a bridge of marine and nonmarine stratigraphic correlation. The ammonite and radiolarian fossils preserved in this group suggest an age from Bajocian to early Valanginian. The J-K boundary was defined in or atop the Tomizawa Formation of the group according to the ammonite data. The present authors study the fossil spores and pollen newly found from the Tomizawa and Koyamada formations. Three assemblages have been recognized. They are Assemblage 1 （Cyathidites-Classopollis） from the upper part of the Tomizawa Formation, Assemblage 2 （Cyathidites-Jiaohepollis） from the lower part of the Koyamada Formation, and Assemblage 3 （Cyathidites-Spheripollenites-Ephedripites） from the middle to upper part of the Koyamada Formation. With the reference of ammonite evidence, the J-K boundary can be defined between Assemblage 1 and Assemblage 2. This palynological J-K boundary can be correlated with that of terrestrial sequence in China. However, local biostratigraphy imply that the continental J-K boundary in China is of 135 or 137 Ma age. It has a considerable discrepancy from the marine standard. Biogeographically, the distribution pattern of spores and pollen in southern China is in accordance with that in the Somanakamura Group, which parallels the Tuchengzi Formation in northeastern China. By the palynological correlation between the Somanakamura Group and the strata in southern China, and then with the sequence in northeastern China, it is suggested that the continental J-K boundary is located in the Tuchengzi Formation.展开更多
In the greenhouse world of the Early UpperCretaceous of Europe giant cephalopod shells of thehemibenthic ammonite Puzosia formed hugeaccumulations.Their shells indicate adaptations in thebody chamber morphology depend...In the greenhouse world of the Early UpperCretaceous of Europe giant cephalopod shells of thehemibenthic ammonite Puzosia formed hugeaccumulations.Their shells indicate adaptations in thebody chamber morphology depending on theenvironment.On the sea floor,deposited ammonite shellsscoured up to 50 cm depth which caught more and morelarge shells over extended periods of time.They built upto five square meter extended scour troughs in which theshells are enriched in chain-,fan-and fan layer orderswith a maximum accumulation of 24 cephalopods.Between these hundreds of other macrofaunal remainsaccumulated.The ammonite shells were benthic islandsand minibiotopes in carbonate soft-to firm groundenvironments along a submarine swell in the southernNorth Sea Basin of Central Europe.The empty shellsencrusted by different epizoans sheltered and protectedalso crustaceans,which undermined the empty shells bybioturbation.Small and extremely rare squamate reptilesof the marine Dolichosaurus longicollis possibly tookshelter or fed within these unique benthic submarinedepression“islands”.展开更多
Elaborate and precise replicas taken from real fossils are used for academic researches in place of originals. They are often exhibited in museums in order to avoid demolition of the fragile originals.Replicas not onl...Elaborate and precise replicas taken from real fossils are used for academic researches in place of originals. They are often exhibited in museums in order to avoid demolition of the fragile originals.Replicas not only increase the number of specimens but also expand the chances for people to get direct observation of scientifically valuable materials.Up to now。展开更多
A section in the Zhepure Mountains near Old Tingri in SE-Tibet,ranging from the Upper Albian to Paleogene,was described in detail by Willems et al.(1996).These authors worked on the litho-and microfacies and set up th...A section in the Zhepure Mountains near Old Tingri in SE-Tibet,ranging from the Upper Albian to Paleogene,was described in detail by Willems et al.(1996).These authors worked on the litho-and microfacies and set up the biostratigraphical framework by planktonic foraminifera.Willems et al.(1996)established their section as a standard for southern Tibet and compared it to the Gamba area.During the 2004 Tibet-expedition of Chengdu University of Technology in China,in co-operation with Bremen and Kiel universities in Germany,the locality was revisited for the purpose of collecting invertebrate fossils.This field-work included only the Upper Cretaceous part of the Tingri section and its invertebrate faunal content.Until today almost no ammonite and inoceramid data existed for this section.This is true for most Cretaceous sections in Tibet,although the Upper Cretaceous succession was interpreted as shelf environment.which in other parts of the world contains rich faunas of these macrofossil groups.The newly discovered continuous record of rare ammonites and inoceramids is probably limited since the preservation in the wacke-and packstones is poor.In addition,sampling conditions were unfavorable and the environmental conditions disadvantageous for most groups of invertebrates,as possibly indicated by larger amounts of small bivalve debris(filaments)in the upper part of the Gamba Group.Although the collected fauna is sparse and poorly preserved,the following biostratigraphical data can be added to the hitherto described microfauna:Calycoceras?from the Upper Gamba Group is Late Cenomanian in age and is accompanied by indeterminable juvenile desmoceratids.Superjacent follows a record of the ammonite Forresteria sp.,indicating that this level in the upper part of the Gamba Group belongs to the Lower Coniacian.This supports the finding of Inoceramus(Cremnoceramus)waltersdorfensis?hannovrensis?from the same interval.Anagaudryceras?is an individual ammonite finding from the Zhepure Shanbei or Zhepure Shanpo Formation,corresponding to the Santonian-Maastrichtian part of the succession.展开更多
The Global Stratotype Section and Point(GSSP)for the base of Toarcian Stage,Lower Jurassic,is placed at the base of micritic limestone bed 15e at Ponta do Trovão(Peniche,Lusitanian Basin,Portugal;coordinates:39&#...The Global Stratotype Section and Point(GSSP)for the base of Toarcian Stage,Lower Jurassic,is placed at the base of micritic limestone bed 15e at Ponta do Trovão(Peniche,Lusitanian Basin,Portugal;coordinates:39°22′15″N,9°23′07″W),80km north of Lisbon,and coincides with the mass occurrence of the ammonite Dactylioceras(Eodactylites).The Pliensbachian/Toarcian boundary(PLB/TOA)is contained in a continuous section forming over 450m of carbonate-rich sediments.Tectonics,syn-sedimentary disturbance,metamorphism or significant diagenesis do not significantly affect this area.At the PLB/TOA,no vertical facies changes,stratigraphical gaps or hiatuses have been recorded.The base of the Toarcian Stage is marked in the bed 15e by the first occurrence of D.(E.)simplex,co-occurring with D.(E.)pseudocommune and D.(E.)polymorphum.The ammonite association of D.(Eodactylites)ssp.and other species e.g.Protogrammoceras(Paltarpites)cf.展开更多
Calibration of numerical ages to the geological time scale is a long scientific pursuit that requires the integration of multiple data sets. A case study of the Albian/Cenomanian stage boundary, also the Lower/Upper C...Calibration of numerical ages to the geological time scale is a long scientific pursuit that requires the integration of multiple data sets. A case study of the Albian/Cenomanian stage boundary, also the Lower/Upper Cretaceous series boundary, illustrates the calibration process. The numerical age of this boundary has shifted from 96 Ma to 99 Ma over a time span of nearly fifty years. Recalibration resulted first from improvements in radiometric dating, and later from inferences about ammonite phylogeny, and most recently from radiometric dates of newly discovered volcanic beds interbedded with diagnostic guide fossils. However, the calibration process continues with study of cosmopolitan dinoflagellates.展开更多
The Almonacid de la Cuba section,located in the Iberian Range,in central-eastern Spain,contains an outstanding record of the Pliensbachian-Toarcian boundary(Early Jurassic).Four ammonite assemblages,characterized resp...The Almonacid de la Cuba section,located in the Iberian Range,in central-eastern Spain,contains an outstanding record of the Pliensbachian-Toarcian boundary(Early Jurassic).Four ammonite assemblages,characterized respectively by the presence of Pleuroceras,Canavaria,Dactylioceras(Eodactylites)and Dactylio-ceras(Orthodactylites)have been distinguished.展开更多
This work reports a synthesis of biostratigraphic outputs resulting from over two decades of comprehensive analysis on the expressive stratigraphic record of the Aalenian of the Lusitanian Basin(Western Iberian Margin...This work reports a synthesis of biostratigraphic outputs resulting from over two decades of comprehensive analysis on the expressive stratigraphic record of the Aalenian of the Lusitanian Basin(Western Iberian Margin;Portugal).The rich and diverse ammonite record studied from ten marly and marlylimestones sections,outcropping in different sectors of the basin ranging from distal to proximal facies,has enabled the establishment of a detailed ammonite-based biostratigraphical framework correlated with other basins located around the Iberian Plate.The study of the benthic foraminiferal assemblages occurring in the basin at the same time interval has allowed the establishment of a biostratigraphic scale based on microfossils accurately calibrated with the ammonite record,an important tool in log interpretation in the context of hydrocarbon exploration activities in sedimentary basins of Jurassic age.展开更多
The Global Stratotype Section and Point(GSSP)defining the base of the Jurassic System Lower Jurassic Epoch and Hettangian Stage is situated at the Kuhjoch pass,Karwendel Mountains,Northern Calcareous Alps,Austria(47&#...The Global Stratotype Section and Point(GSSP)defining the base of the Jurassic System Lower Jurassic Epoch and Hettangian Stage is situated at the Kuhjoch pass,Karwendel Mountains,Northern Calcareous Alps,Austria(47°29'02"N/11°31'50"E).The Triassic-Jurassic(T-J)boundary is exposed at Kuhjoch West and at Kuhjoch East,and corresponds to the first occurrence(FO)of the ammonite Psiloceras spelae tirolicum.The“Golden Spike”was fixed at Kuhjoch East.The section displays a high and continuous sedimentation rate with a constant facies trend across the boundary level.展开更多
End-Triassic ammonoid and bivalve faunas of the Germig area, Tibetan Himalaya, lived in a tropical, shallow-water environment during the Triassic-Jurassic boundary interval. High stratigraphic resolution based on ammo...End-Triassic ammonoid and bivalve faunas of the Germig area, Tibetan Himalaya, lived in a tropical, shallow-water environment during the Triassic-Jurassic boundary interval. High stratigraphic resolution based on ammonite-biochrons allows to tracing the place of origin of several faunal elements. The bivalves Aguilerella and Ctenostreon occurred first in the Tibetan Himalaya and migrated from there to the eastern South Pacific, exhibiting a pantropic dispersal pattern. This dispersal route is supported by the distribution pattern of the ammonites Choristoceras, Discamphiceras, Pleuroacanthites, and Psiloceras calliphyllum. A few taxa, which went extinct everywhere else by the end of the Triassic, survived in the Tibetan Himalaya into early Early Jurassic times. They include the ammonites Choristoceras and Eopsiloceras, and the bivalves Newaagia, Terquemia, Persia, Ryderia guangdongensis, and Cultriopsis angusta. This suggests that the Tibetan Himalaya may have played a refugia role in the course of the end-Triassic mass extinction.展开更多
The current ammonite- and buchiid-based biostratigraphical successions of the Volgian Stage are outlined, with an analysis of the most important data that support correlation throughout the Panboreal Superrealm. Updat...The current ammonite- and buchiid-based biostratigraphical successions of the Volgian Stage are outlined, with an analysis of the most important data that support correlation throughout the Panboreal Superrealm. Updated ammonite zonal schemes were proposed for the Volgian of the type region (the Russian Platform) and Svalbard. The lower Volgian successions in all areas except the Russian Platform, with its eudemic virgatitid lineage and Submediterranean faunal elements, were dominated by Pectinatites and Eosphinctoceras-Subdichotomoceras. The last two genera were especially common eastwards from the Ural Mountains. During the middle Volgian, provincialism developed quickly within the ammonites, and unified assemblages with early Palvovia and Dorsoplanites at the base of the substage were replaced by numerous local eudemic faunas. Despite this, migrations of species of Crendonites, Laugeites, Epivirgatites Epipallasiceras, Epilaugeites, and Taimyrosphinctes occurred at regular intervals and these enable precise correlations between the faunal sub-provinces. The zonation of the upper Volgian is mainly based upon the succession of Craspedites (on Subcraspedites in England and North Sea), and can be traced throughout the Arctic. Zonation based on the bivalve Buchia enables correlations to be made between the successions over much of the Northern Hemisphere, including Northern California, British Columbia, Arctic areas, and the Russian Platform. Each substage of the Volgian is characterized by buchiids with different types of the ontogenetic development. Research on the infrazonal subdivision of the Volgian Stage based on buchiids is currently in progress. Our analyses of the ammonite and buchiid successions of the Panboreal Superrealm lead us to conclude that there are no major faunal gaps in Volgian successions of the Russian Platform and Northern Siberia.展开更多
The stratigraphic record shows a considerable decrease in ammonoid taxonomic diversity and distinct changes of ammonite shell morphology toward end of the Jurassic in the Central Russian Basin. By the end-Volgian, amm...The stratigraphic record shows a considerable decrease in ammonoid taxonomic diversity and distinct changes of ammonite shell morphology toward end of the Jurassic in the Central Russian Basin. By the end-Volgian, ammonites were represented by only two genera, belonging to a single family Craspeditidae, which differ markedly from previous ammonite families in their shell form. The end-Jurassic decrease in ammonoid biodiversity started in the mid-Volgian and is mainly correlated with shallowing of the shelf.展开更多
The Kutch Basin of western India is famous for its rich assemblages of the Callovian-Oxfordian ammonites.The family Oppelidae Douvillé is the second most diverse ammonite group after perisphinctids during the Mid...The Kutch Basin of western India is famous for its rich assemblages of the Callovian-Oxfordian ammonites.The family Oppelidae Douvillé is the second most diverse ammonite group after perisphinctids during the Middle-Upper Jurassic.Hecticoceratinae is the most diverse subfamily within Oppelidae and has wide palaeobiogeographic(near cosmopolitan) and temporal distributions(Bathonian-Oxfordian).Some species were well timediagnostic and thus help in interprovincial correlation.The taxonomy of the subfamily Hecticoceratinae of Kutch was in a state of flux until recently.It was not revised since Spath’s(1927-1933) great contribution.Many genera and species were morphogenera or morphospecies and they again suffer from excessive subjective splitting.It was therefore badly needed for a comprehensive taxonomic revision of the subfamily with modern aspects of systematics i.e.,sexual dimorphism and population dynamics.A lithostratigraphic framework has already been well documented in the Kutch Basin of western India.A high resolution biostratigraphy incorporating stage-intrastage fossil assemblages have been used in interbasinal correlation based on the Callovian-Oxfordian hecticoceratins.Near cosmopolitan distribution of many hecticoceratin genera were widely used for biostratigraphic zonation as well as an understanding of the palaeobiogeographic pattern.The phylogeny of the subfamily Hecticoceratinae has been used to construct the cladograms depicting area relationships among different provinces during the Callovian-Oxfordian.展开更多
文摘The Upper Cretaceous successions of Wadi Umm-Khayshar,southern Galala Plateau,North Eastern Desert,Egypt,are composed of highly diversified faunas and subdivided from base to top into the Galala(Middle-Late Cenomanian),Maghra El Hadida(Latest Cenomanian-Late Turonian),Matulla(Coniacian-Santonian),and Sudr(Campanian-Maastrichtian)formations.Five ammonite biozones are recorded in the studied section:Neolobites vibrayeanus,Vascoceras cauvini(late Cenomanian),Vascoceras proprium,Choffaticeras segne,and Coilopoceras requienianum(Turonian)zones.The paleoenvironments of the Upper Cretaceous succession are interpreted based on detailed study and microfacies analysis that reflect a deposition in a homoclinal ramp platform ranging from intertidal to deep subtidal.The paleoecology of the Cenomanian-Turonian succession in the studied section is explained based on a detailed study of macrofaunal associations and sedimentary facies.Quantitative analysis(Q-mode cluster analysis,using the Raup-Crick Paired group method)of 1029 macrobenthic specimens,including 45 species of mollusks and echinoids yielded five macrofaunal associations(A-E)that are described and interpreted as remnants of communities.The nektonic elements are represented by 235 cephalopod specimens of 20 species;heatmap cluster analyses show the distribution of these specimens during the Upper Cenomanian-Turonian stages.Environmental parameters(substrate consistency,rate of sedimentation,water energy,surface-water productivity,and oxygen availability)controlled the distribution of the studied macrofauna.The five associations are divided into two major groups:low-stress associations(A,B,C,and D),and a highstress association(E).The low stress associations are recorded from two different habitats:(1)a high-energy,firm substrate habitat,dominated by epifaunal bivalves,large epifaunal gastropods and a regular echinoid;(2)a low-energy,soft substrate habitat dominated by infaunal bivalves and echinoids.The high stress association is dominated by only two species and recorded from a high-energy shoal environment during a regression phase.A detailed study of macrobenthos and cephalopods provides a good paleoecological understanding of Cenomanian-Turonian succession in the Wadi Umm-Khayshar section.
文摘Following votes by the Barremian Working Group,the International Subcommission on Cretaceous Stratigraphy and the International Commission on Stratigraphy,the Executive Committee of the International Union of Geological Sciences unanimously approved in March 2023 the Global Stratotype Section and Point(GSSP)for the Barremian Stage(Lower Cretaceous).The base of the Barremian Stage is defined at the base of bed 171 of the Río Argos section,near Caravaca(SE Spain)and correlated by the first appearance of the ammonite species Taveraidiscus hugii.This event falls within the NC5C calcareous nannofossil Subzone,the Lilliputianella semielongata planktonic foraminiferal Zone,and the Dorothia ouachensis benthic foraminiferal Zone.It roughly coincides with the beginning of a slightly negative trend interval in theδ^(13)C curve.Indirect calibration to the magnetostratigraphic scale suggests that the boundary falls in the lowermost part of polarity chron M3r.According to the astrochronological analysis,a time interval of 0.74 myr separates the beginning of the late Hauterivian Faraoni Episode from the base of the Barremian,which is dated at 125.77 MA.
文摘The 'Falang Formation' of western Guizhou was previously called the 'Halobia Bed' and considered to be I .adinian in age. It was subdivided upward into the Zhuganpo, Laishike and Longchang members based on ammonites and the Trachyceras multitubertulatum Zone of the Longchang Member was put in the Lower Carnian. Here in the present paper, 4 genera and 9 species of ammonites and 1 nautiloid genus and species collected from the upper part of the 'Falang Formation' (i.e. the Wayao Formation used in this paper, equivalent to the Laishike Member from Guanling and Zhenfeng counties are described. The geological and geographical distribution of these cephalopods, as well as the co-existing conodonts, put the Wayao Formation to the late early Carnmian.
基金supported by the National Natural Science Foundation of China(Project NO.41172037)the National Basic Research Program of China(973 Program,NO.2012CB822002)the China Geological Survey(Project NO.1212011120142)
文摘Defining the Jurassic-Cretaceous boundary is a controversy in stratigraphic study of the world. It has been widely accepted that this boundary can be defined at the bottom of Berriasian in Tetbys, with the appearance of the ammonite Berriasellajacobi dating to ca. 145 Ma. However, it is difficult for the widespread terrestrial deposits in China to correlate with the international standard of marine facies. The Somanakamura Group in Japan is represented by a succession of marinecontinental transitional strata. It provides a bridge of marine and nonmarine stratigraphic correlation. The ammonite and radiolarian fossils preserved in this group suggest an age from Bajocian to early Valanginian. The J-K boundary was defined in or atop the Tomizawa Formation of the group according to the ammonite data. The present authors study the fossil spores and pollen newly found from the Tomizawa and Koyamada formations. Three assemblages have been recognized. They are Assemblage 1 （Cyathidites-Classopollis） from the upper part of the Tomizawa Formation, Assemblage 2 （Cyathidites-Jiaohepollis） from the lower part of the Koyamada Formation, and Assemblage 3 （Cyathidites-Spheripollenites-Ephedripites） from the middle to upper part of the Koyamada Formation. With the reference of ammonite evidence, the J-K boundary can be defined between Assemblage 1 and Assemblage 2. This palynological J-K boundary can be correlated with that of terrestrial sequence in China. However, local biostratigraphy imply that the continental J-K boundary in China is of 135 or 137 Ma age. It has a considerable discrepancy from the marine standard. Biogeographically, the distribution pattern of spores and pollen in southern China is in accordance with that in the Somanakamura Group, which parallels the Tuchengzi Formation in northeastern China. By the palynological correlation between the Somanakamura Group and the strata in southern China, and then with the sequence in northeastern China, it is suggested that the continental J-K boundary is located in the Tuchengzi Formation.
基金supported by grants, between 1994-2001,from the Deutsche Forschungsgesellschaft (DFG Str.98/3)the LandNorth-Rhine Westphalia (City Halle/Westph.)+2 种基金the LandkreisOsnabrück, the Bezirksregierung Detmold, the NaturparkvereinNördlicher Teutoburger Wald-Wiehengebirge e.V.the HeimatvereinBorgholzhausen e. V.the Naturkundemuseum Bielefeld.
文摘In the greenhouse world of the Early UpperCretaceous of Europe giant cephalopod shells of thehemibenthic ammonite Puzosia formed hugeaccumulations.Their shells indicate adaptations in thebody chamber morphology depending on theenvironment.On the sea floor,deposited ammonite shellsscoured up to 50 cm depth which caught more and morelarge shells over extended periods of time.They built upto five square meter extended scour troughs in which theshells are enriched in chain-,fan-and fan layer orderswith a maximum accumulation of 24 cephalopods.Between these hundreds of other macrofaunal remainsaccumulated.The ammonite shells were benthic islandsand minibiotopes in carbonate soft-to firm groundenvironments along a submarine swell in the southernNorth Sea Basin of Central Europe.The empty shellsencrusted by different epizoans sheltered and protectedalso crustaceans,which undermined the empty shells bybioturbation.Small and extremely rare squamate reptilesof the marine Dolichosaurus longicollis possibly tookshelter or fed within these unique benthic submarinedepression“islands”.
文摘Elaborate and precise replicas taken from real fossils are used for academic researches in place of originals. They are often exhibited in museums in order to avoid demolition of the fragile originals.Replicas not only increase the number of specimens but also expand the chances for people to get direct observation of scientifically valuable materials.Up to now。
文摘A section in the Zhepure Mountains near Old Tingri in SE-Tibet,ranging from the Upper Albian to Paleogene,was described in detail by Willems et al.(1996).These authors worked on the litho-and microfacies and set up the biostratigraphical framework by planktonic foraminifera.Willems et al.(1996)established their section as a standard for southern Tibet and compared it to the Gamba area.During the 2004 Tibet-expedition of Chengdu University of Technology in China,in co-operation with Bremen and Kiel universities in Germany,the locality was revisited for the purpose of collecting invertebrate fossils.This field-work included only the Upper Cretaceous part of the Tingri section and its invertebrate faunal content.Until today almost no ammonite and inoceramid data existed for this section.This is true for most Cretaceous sections in Tibet,although the Upper Cretaceous succession was interpreted as shelf environment.which in other parts of the world contains rich faunas of these macrofossil groups.The newly discovered continuous record of rare ammonites and inoceramids is probably limited since the preservation in the wacke-and packstones is poor.In addition,sampling conditions were unfavorable and the environmental conditions disadvantageous for most groups of invertebrates,as possibly indicated by larger amounts of small bivalve debris(filaments)in the upper part of the Gamba Group.Although the collected fauna is sparse and poorly preserved,the following biostratigraphical data can be added to the hitherto described microfauna:Calycoceras?from the Upper Gamba Group is Late Cenomanian in age and is accompanied by indeterminable juvenile desmoceratids.Superjacent follows a record of the ammonite Forresteria sp.,indicating that this level in the upper part of the Gamba Group belongs to the Lower Coniacian.This supports the finding of Inoceramus(Cremnoceramus)waltersdorfensis?hannovrensis?from the same interval.Anagaudryceras?is an individual ammonite finding from the Zhepure Shanbei or Zhepure Shanpo Formation,corresponding to the Santonian-Maastrichtian part of the succession.
基金supported by the BIOSCALES Project(POCTI/36438/PAL/2000)coordinated by the Universidade NOVA de Lisboa+1 种基金R.B.Rocha thanks the support of A.F.Soares,J.C.Kullberg,P.S.Caetano and P.H.VerdialFinancial support was provided to L.V.Duarte,S.Pinto and M.C.Cabral by Projects PDCTE/CTA/44907/2002 and PTDC/CTE-GIX/098968/2008.
文摘The Global Stratotype Section and Point(GSSP)for the base of Toarcian Stage,Lower Jurassic,is placed at the base of micritic limestone bed 15e at Ponta do Trovão(Peniche,Lusitanian Basin,Portugal;coordinates:39°22′15″N,9°23′07″W),80km north of Lisbon,and coincides with the mass occurrence of the ammonite Dactylioceras(Eodactylites).The Pliensbachian/Toarcian boundary(PLB/TOA)is contained in a continuous section forming over 450m of carbonate-rich sediments.Tectonics,syn-sedimentary disturbance,metamorphism or significant diagenesis do not significantly affect this area.At the PLB/TOA,no vertical facies changes,stratigraphical gaps or hiatuses have been recorded.The base of the Toarcian Stage is marked in the bed 15e by the first occurrence of D.(E.)simplex,co-occurring with D.(E.)pseudocommune and D.(E.)polymorphum.The ammonite association of D.(Eodactylites)ssp.and other species e.g.Protogrammoceras(Paltarpites)cf.
基金funded principally by collaborative National Science Foundation Grants EAR-9909601,EAR-9909199,and EAR-9909601 to John M.Holbrook,then at Southeast Missouri State University,to Francisca Oboh-Ikuenobe,University of Missouri at Rolla,and R.W.Scott,University of Tulsa,respectivelyin part supported by the National Key Basic Research Program,the Ministry of Science and Technology of China(MOST 973 Program,2006CB701400),and is a contribution to IGCP 463/555.
文摘Calibration of numerical ages to the geological time scale is a long scientific pursuit that requires the integration of multiple data sets. A case study of the Albian/Cenomanian stage boundary, also the Lower/Upper Cretaceous series boundary, illustrates the calibration process. The numerical age of this boundary has shifted from 96 Ma to 99 Ma over a time span of nearly fifty years. Recalibration resulted first from improvements in radiometric dating, and later from inferences about ammonite phylogeny, and most recently from radiometric dates of newly discovered volcanic beds interbedded with diagnostic guide fossils. However, the calibration process continues with study of cosmopolitan dinoflagellates.
基金financed by projects CGL2008-01273,CGL2008-02203 and CGL2008-03112/BTE of the Spanish Ministerio de Educación.
文摘The Almonacid de la Cuba section,located in the Iberian Range,in central-eastern Spain,contains an outstanding record of the Pliensbachian-Toarcian boundary(Early Jurassic).Four ammonite assemblages,characterized respectively by the presence of Pleuroceras,Canavaria,Dactylioceras(Eodactylites)and Dactylio-ceras(Orthodactylites)have been distinguished.
基金supported by FEDER funds through the Competitiveness Factors Operational Programme-COMPETE and national funds by FCT in the frame of the UID/Multi00073/2013 projectThe study is a contribution for the Projects CGL2011-23947 and CGL2011-25894(Ministerio de Ciencia e Innovación,Spain)+1 种基金for the Grupo de Investigación UCM 910431(Complutense University,Madrid,Spain).supported by the Consórcio Petrobras-Galp-Partex of Portugal.
文摘This work reports a synthesis of biostratigraphic outputs resulting from over two decades of comprehensive analysis on the expressive stratigraphic record of the Aalenian of the Lusitanian Basin(Western Iberian Margin;Portugal).The rich and diverse ammonite record studied from ten marly and marlylimestones sections,outcropping in different sectors of the basin ranging from distal to proximal facies,has enabled the establishment of a detailed ammonite-based biostratigraphical framework correlated with other basins located around the Iberian Plate.The study of the benthic foraminiferal assemblages occurring in the basin at the same time interval has allowed the establishment of a biostratigraphic scale based on microfossils accurately calibrated with the ammonite record,an important tool in log interpretation in the context of hydrocarbon exploration activities in sedimentary basins of Jurassic age.
基金sponsored by the Austrian National Committee(Austrian Academy of Sciences)for IGCPfinancial support from the HP program of Utrecht University(The Netherlands)partial support from the US National Science Foundation(Grant EAR 0518605).
文摘The Global Stratotype Section and Point(GSSP)defining the base of the Jurassic System Lower Jurassic Epoch and Hettangian Stage is situated at the Kuhjoch pass,Karwendel Mountains,Northern Calcareous Alps,Austria(47°29'02"N/11°31'50"E).The Triassic-Jurassic(T-J)boundary is exposed at Kuhjoch West and at Kuhjoch East,and corresponds to the first occurrence(FO)of the ammonite Psiloceras spelae tirolicum.The“Golden Spike”was fixed at Kuhjoch East.The section displays a high and continuous sedimentation rate with a constant facies trend across the boundary level.
基金Supported by National Natural Science Foundation of China(Grant Nos.40572013,40672012)the National Bureau of Geological Survey(Grant No.1212010818095)
文摘End-Triassic ammonoid and bivalve faunas of the Germig area, Tibetan Himalaya, lived in a tropical, shallow-water environment during the Triassic-Jurassic boundary interval. High stratigraphic resolution based on ammonite-biochrons allows to tracing the place of origin of several faunal elements. The bivalves Aguilerella and Ctenostreon occurred first in the Tibetan Himalaya and migrated from there to the eastern South Pacific, exhibiting a pantropic dispersal pattern. This dispersal route is supported by the distribution pattern of the ammonites Choristoceras, Discamphiceras, Pleuroacanthites, and Psiloceras calliphyllum. A few taxa, which went extinct everywhere else by the end of the Triassic, survived in the Tibetan Himalaya into early Early Jurassic times. They include the ammonites Choristoceras and Eopsiloceras, and the bivalves Newaagia, Terquemia, Persia, Ryderia guangdongensis, and Cultriopsis angusta. This suggests that the Tibetan Himalaya may have played a refugia role in the course of the end-Triassic mass extinction.
基金Supported by RFBR (Grant No. 09-05-00456)Grant of the President of the Russian Federation (Grant No. MK-856.2008.5)Program of the Presidium of RAS (Grant No. 16)
文摘The current ammonite- and buchiid-based biostratigraphical successions of the Volgian Stage are outlined, with an analysis of the most important data that support correlation throughout the Panboreal Superrealm. Updated ammonite zonal schemes were proposed for the Volgian of the type region (the Russian Platform) and Svalbard. The lower Volgian successions in all areas except the Russian Platform, with its eudemic virgatitid lineage and Submediterranean faunal elements, were dominated by Pectinatites and Eosphinctoceras-Subdichotomoceras. The last two genera were especially common eastwards from the Ural Mountains. During the middle Volgian, provincialism developed quickly within the ammonites, and unified assemblages with early Palvovia and Dorsoplanites at the base of the substage were replaced by numerous local eudemic faunas. Despite this, migrations of species of Crendonites, Laugeites, Epivirgatites Epipallasiceras, Epilaugeites, and Taimyrosphinctes occurred at regular intervals and these enable precise correlations between the faunal sub-provinces. The zonation of the upper Volgian is mainly based upon the succession of Craspedites (on Subcraspedites in England and North Sea), and can be traced throughout the Arctic. Zonation based on the bivalve Buchia enables correlations to be made between the successions over much of the Northern Hemisphere, including Northern California, British Columbia, Arctic areas, and the Russian Platform. Each substage of the Volgian is characterized by buchiids with different types of the ontogenetic development. Research on the infrazonal subdivision of the Volgian Stage based on buchiids is currently in progress. Our analyses of the ammonite and buchiid successions of the Panboreal Superrealm lead us to conclude that there are no major faunal gaps in Volgian successions of the Russian Platform and Northern Siberia.
基金Supported by Program of the Presidium of the Russian Academy of Sciences "Origin of the Biosphere and the Evolution of Geo-biological Systems"
文摘The stratigraphic record shows a considerable decrease in ammonoid taxonomic diversity and distinct changes of ammonite shell morphology toward end of the Jurassic in the Central Russian Basin. By the end-Volgian, ammonites were represented by only two genera, belonging to a single family Craspeditidae, which differ markedly from previous ammonite families in their shell form. The end-Jurassic decrease in ammonoid biodiversity started in the mid-Volgian and is mainly correlated with shallowing of the shelf.
基金completed under UGC Minor Research Project Scheme [F.PSW008/11-12(ERO)]
文摘The Kutch Basin of western India is famous for its rich assemblages of the Callovian-Oxfordian ammonites.The family Oppelidae Douvillé is the second most diverse ammonite group after perisphinctids during the Middle-Upper Jurassic.Hecticoceratinae is the most diverse subfamily within Oppelidae and has wide palaeobiogeographic(near cosmopolitan) and temporal distributions(Bathonian-Oxfordian).Some species were well timediagnostic and thus help in interprovincial correlation.The taxonomy of the subfamily Hecticoceratinae of Kutch was in a state of flux until recently.It was not revised since Spath’s(1927-1933) great contribution.Many genera and species were morphogenera or morphospecies and they again suffer from excessive subjective splitting.It was therefore badly needed for a comprehensive taxonomic revision of the subfamily with modern aspects of systematics i.e.,sexual dimorphism and population dynamics.A lithostratigraphic framework has already been well documented in the Kutch Basin of western India.A high resolution biostratigraphy incorporating stage-intrastage fossil assemblages have been used in interbasinal correlation based on the Callovian-Oxfordian hecticoceratins.Near cosmopolitan distribution of many hecticoceratin genera were widely used for biostratigraphic zonation as well as an understanding of the palaeobiogeographic pattern.The phylogeny of the subfamily Hecticoceratinae has been used to construct the cladograms depicting area relationships among different provinces during the Callovian-Oxfordian.
