Chronostratigraphy and Microfossil-Derived Sea-Level History of the Qiong Dong Nan and Ying Ge Hai Basins, South China Sea
Peter R. Thompson, William H. Abbott, 2003. "Chronostratigraphy and Microfossil-Derived Sea-Level History of the Qiong Dong Nan and Ying Ge Hai Basins, South China Sea", Micropaleontologic Proxies for Sea-Level Change and Stratigraphic Discontinuities, Hilary Clement Olson, R. Mark Leckie
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Analysis of biostratigraphic information from 31 industry wells in the Qiong Dong Nan and Ying Ge Hai Basins in the South China Sea establishes a chronostratigraphy for the area. Microfossil biostratigraphy of the wells permits recognition of individual regressive sequences and overlying marine flooding events. Dating of the sequences and unconformities shows a definite correlation of the transgressions and regressions to those depicted on published global sea-level curves. This tie indicates the influence of sea level on sediment dispersal enhancing local rift-related deposition.
Age control developed for the basins in this study has improved stratigraphic correlations by verifying seismic-to-well ties and providing bracketing ages across hiatuses. Wells in the basins penetrate a thick Holocene–Pliocene clastic interval to reach an Upper Miocene deep-water clastic reservoir in offshore downdip wells or a Lower Miocene–Upper Oligocene shallow-water clastic reservoir horizon on structural highs. Although the hydrocarbon source is assumed to be local Lower Tertiary (Eocene or older) nonmarine coals, these units have not yet been reached by drilling. The regional seal is an upper Middle Miocene marine flooding event.
Paleoecology and paleobathymetry were determined on the basis of foraminiferal analyses. Biostratigraphic dating with foraminifera and calcareous nannofossils permits construction of time-slice maps to show the basin configuration at correlative horizons. Synthesis of many individual well paleobathymetry curves yields a general sea-level curve for the basins. The overall shape of this sea-level curve compares favorably with published global curves.
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Micropaleontology and biostratigraphy play vital roles for deciphering the stratigraphic record produced by changes in relative sea level, interpreting the history of global sea-level change, and testing models for the causes of sea-level fluctuations due to the variable influences of tectonics, glacio-eustasy, and climate. The stratigraphic architecture developed in response to changing eustasy, accommodation space, and sediment supply along continental margins, in epicontinental seas, and on carbonate platforms can be interpreted using the tools of marine micropaleontology. Microfossils provide chronostratigraphic control and a wealth of paleoenvironmental information about depositional environments as well as post-depositional changes to those environments. This volume demonstrates clearly that micropaleontologic proxies of environmental change provide a powerful dimension to the interpretive potential of stratigraphic sequences produced by changes in relative sea level and eustasy. Studies in the volume range from paralic to bathyal environments, span Pennsylvanian through Holocene stratigraphy, encompass a variety of microfossil groups and include a wide spectrum of techniques and paleoenvironmental proxies. The volume has been designed for graduate students and professionals interested in a wide range of subjects.