During the last decades,several integrated studies of Tethyan Jurassic/Cretaceous boundary sections from different countries were published with the objective to indicate problems for the selection of biological,chemi...During the last decades,several integrated studies of Tethyan Jurassic/Cretaceous boundary sections from different countries were published with the objective to indicate problems for the selection of biological,chemical or physical markers suitable for identification of the Jurassic/Cretaceous boundary-the only system boundary within the Phanerozoic still not fixed by GSSP.Drawing the boundary between the Jurassic and Cretaceous systems is a matter of global scale discussions.The problem of proposing possible J/K boundary stratotypes results from lack of a global index fossils, global sea level drop,paleogeographic changes causing development of isolated facies areas,as well as from the effect of Late Cimmerian Orogeny.This contribution summarizes and comments data on J/K boundary interval obtained from several important Tethyan sections and shows still existing problems and discrepancies in its determination.展开更多
The uppermost Jurassic to Lower Cretaceous in the Qomolongma (Mt. Everest) area were deposited in a strong subsiding setting on passive continental margin. From Tithonian to Valanginian, the area experienced an enviro...The uppermost Jurassic to Lower Cretaceous in the Qomolongma (Mt. Everest) area were deposited in a strong subsiding setting on passive continental margin. From Tithonian to Valanginian, the area experienced an environment shift from circum\|shelf margin carbonate platform to foreslope, then to deep continental slope [1] . Correspondingly, the sediments change in vertical succession from quartz sandstone, via carbonate grainstone to dark shale intercalated with lithic sandstone of gravity flow. From the Tithonian to Valanginian, eight 3rd\|order sequences have been recognized [1] with clearly delineated sequence boundaries and reasonable biostratigraphic controls of ammonites. From the angle of sequence stratigraphy and sedimentary cycles, the important change happened at ca. 138Ma [2] of the Lower Tithonian (about 120m above Aulacosphinctoides hybonotum zone), where a waved subaerial erosion surface occurs in massive bioclastic grainstone. The boundary at ca. 134 5Ma (latest Tithonian, about 60m below the FAD of \%Berriasella cf. jacobi [3] ) comes to the next. The third one is at ca 132Ma (some 170m above the FAD of Berriasella cf. jacobi [3] , but about 60m below the FAD of Berriasella cf. grandis [3] ). In terms of sea\|level change, the sequence boundary at 134 5Ma is probably the most distinctive one, above which some 60m gravel\|bearing massive medium\|grained quartz sandstone was laid down and obviously truncates the underlying strata. In the dark shale below the sandstone, abundant in ammonites, such as Virgatosphinctes, Aulacosphinctes, Haplophylloceras and Gymnosphinctes are recorded [3] . The quartz sandstone itself does not bear identifiable fossils. Above the quartz sandstone, the strata mainly consists of dark silty shale up to 180m thick, with an prominent marine transgression at the base. Just above the first flooding surface (FFS), quite a number of ammonites such as \%Berriasella\% cf. \%jacobi, Blanofordiceras, Hymalayaites\% and \%Pseudosubplanites \%are documented [3] . The third sequence, which is delineated by submarine truncation of slope fan complexes at bottom, is also characterized by dark shale and silts, yielding ammonites \%Berriasella \%cf. \%grandis\% and B. cf. \%berthei.\%>From the viewpoint of sequence stratigraphy, we herein suggest to take the FFS in the second sequence as the J/K boundary. The sequence boundary below it can be used as a nice auxiliary marker, which represents a large sea\|level fall, and can be correlated widely in the world. From the angle of paleontology, the FFS is also ideal for the boundary, where the most important faunal turnover happened. Theoretically, taking FFS as a chronostratigraphic boundary has more advantages than using sequence boundary.展开更多
J.T.Kingma(1948)的论文“Contributions to the knowledge of the young Cainozoic Ostracoda from the Malayan region”是研究东南亚及其邻近地区新生代介形虫最重要的经典著作之一,文中共描述了97种,其中含42新种和6新属。本文通过...J.T.Kingma(1948)的论文“Contributions to the knowledge of the young Cainozoic Ostracoda from the Malayan region”是研究东南亚及其邻近地区新生代介形虫最重要的经典著作之一,文中共描述了97种,其中含42新种和6新属。本文通过对Kingma(1948)的31个新种原始材料的仔细检查,为其中27个种指定了正模或选模,拍摄了清晰的SEM照片,补充了必要的描述,列出了同义名,总结了它们的分布。作者认为Kingma(1948)的3个新种Clithrocytheridea atjehensis,Cythereis reticulineata和C.bodjonegoroensis分别是Miocyprfdeis spinulosa(Brady,1868),Lankacythere coralloides和Henryhowella keutapangensis(Kingma,1948)的同义名;以Kingma(1948)的Cytherura? Kalibengensis和Cythereis cruysi为模式种分别建立了两个新属: Uroconcha和Kingmacy-there.展开更多
The Sulu orogenic belt is an uplift zone that was formed in the Late Triassic.Several Jurassic to Cretaceous sedimentary successions have been recognized within the Sulu orogenic belt in recent studies,including outcr...The Sulu orogenic belt is an uplift zone that was formed in the Late Triassic.Several Jurassic to Cretaceous sedimentary successions have been recognized within the Sulu orogenic belt in recent studies,including outcrops that are considered to be related to the newly discovered Riqingwei Basin.This basin has been the focus of extensive study due to its continuous Cretaceous rock sequence,geological location and petroleum resource potential.However,the lack of a consolidated chronology for the strata has precluded a better understanding of stratigraphy,tectonic evolution and resource potential of the Riqingwei Basin.Here,we present the results of a new magnetostratigraphic study of the continental scientific drilling borehole LK-1,which is located on Lingshan Island,offshore Shandong province,eastern China.The goals of this study are to(1)refine the Late Jurassic to Early Cretaceous chronostratigraphic framework of the Riqingwei Basin,and(2)investigate the location of the J/K boundary in the Borehole Core LK-1.The observed patterns of the paleomagnetic polarity zone in the LK-1 borehole correlate well with the geomagnetic polarity time scale(GPTS),and the continuous magnetostratigraphy profile defined in this core indicates an age ranging from 146.5 to 125.8 Ma for the samples interval.The sediment accumulation rates(SAR)of LK-1 show one period of high SAR(~10.5 cm kyr^(-1))at 135.3–130.6 Ma and two periods of low SAR(~4.8 and~2.2 cm kyr^(-1))at145.7–135.3 and 130.6–125.8 Ma,respectively.In addition,the magnetostratigraphic results suggest that the Jurassic-Cretaceous(J/K)boundary of the LK-1 is located within the magnetozone N21.2 n(~1254 m).This comprehensive geochronologic framework provides a good correlation of the marine Upper Jurassic to Lower Cretaceous strata in the Riqingwei Basin to other marine strata and continental sequences,in addition to providing a foundation for the study of the structural evolution of eastern China.展开更多
基金the APVV-0280-07,APVV-0248-07APVV- 0465-06+1 种基金APVT 51-011305VEGA 0196 and 0065
文摘During the last decades,several integrated studies of Tethyan Jurassic/Cretaceous boundary sections from different countries were published with the objective to indicate problems for the selection of biological,chemical or physical markers suitable for identification of the Jurassic/Cretaceous boundary-the only system boundary within the Phanerozoic still not fixed by GSSP.Drawing the boundary between the Jurassic and Cretaceous systems is a matter of global scale discussions.The problem of proposing possible J/K boundary stratotypes results from lack of a global index fossils, global sea level drop,paleogeographic changes causing development of isolated facies areas,as well as from the effect of Late Cimmerian Orogeny.This contribution summarizes and comments data on J/K boundary interval obtained from several important Tethyan sections and shows still existing problems and discrepancies in its determination.
基金theNationalNaturalScienceFoundationofChina (No ..4982 5 10 2 )
文摘The uppermost Jurassic to Lower Cretaceous in the Qomolongma (Mt. Everest) area were deposited in a strong subsiding setting on passive continental margin. From Tithonian to Valanginian, the area experienced an environment shift from circum\|shelf margin carbonate platform to foreslope, then to deep continental slope [1] . Correspondingly, the sediments change in vertical succession from quartz sandstone, via carbonate grainstone to dark shale intercalated with lithic sandstone of gravity flow. From the Tithonian to Valanginian, eight 3rd\|order sequences have been recognized [1] with clearly delineated sequence boundaries and reasonable biostratigraphic controls of ammonites. From the angle of sequence stratigraphy and sedimentary cycles, the important change happened at ca. 138Ma [2] of the Lower Tithonian (about 120m above Aulacosphinctoides hybonotum zone), where a waved subaerial erosion surface occurs in massive bioclastic grainstone. The boundary at ca. 134 5Ma (latest Tithonian, about 60m below the FAD of \%Berriasella cf. jacobi [3] ) comes to the next. The third one is at ca 132Ma (some 170m above the FAD of Berriasella cf. jacobi [3] , but about 60m below the FAD of Berriasella cf. grandis [3] ). In terms of sea\|level change, the sequence boundary at 134 5Ma is probably the most distinctive one, above which some 60m gravel\|bearing massive medium\|grained quartz sandstone was laid down and obviously truncates the underlying strata. In the dark shale below the sandstone, abundant in ammonites, such as Virgatosphinctes, Aulacosphinctes, Haplophylloceras and Gymnosphinctes are recorded [3] . The quartz sandstone itself does not bear identifiable fossils. Above the quartz sandstone, the strata mainly consists of dark silty shale up to 180m thick, with an prominent marine transgression at the base. Just above the first flooding surface (FFS), quite a number of ammonites such as \%Berriasella\% cf. \%jacobi, Blanofordiceras, Hymalayaites\% and \%Pseudosubplanites \%are documented [3] . The third sequence, which is delineated by submarine truncation of slope fan complexes at bottom, is also characterized by dark shale and silts, yielding ammonites \%Berriasella \%cf. \%grandis\% and B. cf. \%berthei.\%>From the viewpoint of sequence stratigraphy, we herein suggest to take the FFS in the second sequence as the J/K boundary. The sequence boundary below it can be used as a nice auxiliary marker, which represents a large sea\|level fall, and can be correlated widely in the world. From the angle of paleontology, the FFS is also ideal for the boundary, where the most important faunal turnover happened. Theoretically, taking FFS as a chronostratigraphic boundary has more advantages than using sequence boundary.
文摘J.T.Kingma(1948)的论文“Contributions to the knowledge of the young Cainozoic Ostracoda from the Malayan region”是研究东南亚及其邻近地区新生代介形虫最重要的经典著作之一,文中共描述了97种,其中含42新种和6新属。本文通过对Kingma(1948)的31个新种原始材料的仔细检查,为其中27个种指定了正模或选模,拍摄了清晰的SEM照片,补充了必要的描述,列出了同义名,总结了它们的分布。作者认为Kingma(1948)的3个新种Clithrocytheridea atjehensis,Cythereis reticulineata和C.bodjonegoroensis分别是Miocyprfdeis spinulosa(Brady,1868),Lankacythere coralloides和Henryhowella keutapangensis(Kingma,1948)的同义名;以Kingma(1948)的Cytherura? Kalibengensis和Cythereis cruysi为模式种分别建立了两个新属: Uroconcha和Kingmacy-there.
基金supported by the National Natural Science Foundation of China(Grant Nos.42002030,42072169)National Science and Technology Major Project(Grant No.2016ZX05024-002-001)+1 种基金the Key R&D Plan of Shandong Province(Grant No.2017CXGC1608)the Natural Science Foundation of Shandong Province(Grant No.ZR201910280267)。
文摘The Sulu orogenic belt is an uplift zone that was formed in the Late Triassic.Several Jurassic to Cretaceous sedimentary successions have been recognized within the Sulu orogenic belt in recent studies,including outcrops that are considered to be related to the newly discovered Riqingwei Basin.This basin has been the focus of extensive study due to its continuous Cretaceous rock sequence,geological location and petroleum resource potential.However,the lack of a consolidated chronology for the strata has precluded a better understanding of stratigraphy,tectonic evolution and resource potential of the Riqingwei Basin.Here,we present the results of a new magnetostratigraphic study of the continental scientific drilling borehole LK-1,which is located on Lingshan Island,offshore Shandong province,eastern China.The goals of this study are to(1)refine the Late Jurassic to Early Cretaceous chronostratigraphic framework of the Riqingwei Basin,and(2)investigate the location of the J/K boundary in the Borehole Core LK-1.The observed patterns of the paleomagnetic polarity zone in the LK-1 borehole correlate well with the geomagnetic polarity time scale(GPTS),and the continuous magnetostratigraphy profile defined in this core indicates an age ranging from 146.5 to 125.8 Ma for the samples interval.The sediment accumulation rates(SAR)of LK-1 show one period of high SAR(~10.5 cm kyr^(-1))at 135.3–130.6 Ma and two periods of low SAR(~4.8 and~2.2 cm kyr^(-1))at145.7–135.3 and 130.6–125.8 Ma,respectively.In addition,the magnetostratigraphic results suggest that the Jurassic-Cretaceous(J/K)boundary of the LK-1 is located within the magnetozone N21.2 n(~1254 m).This comprehensive geochronologic framework provides a good correlation of the marine Upper Jurassic to Lower Cretaceous strata in the Riqingwei Basin to other marine strata and continental sequences,in addition to providing a foundation for the study of the structural evolution of eastern China.
基金Supported by National Natural Science Foundation of China (No.10301010 and No.60673048)Natural Science Foundation of Education Ministry of Anhui Province (NO.KJ2007B124).
