The South China Sea; middle to late Miocene proto-warm pool development and the east Asian monsoon

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Author(s): Nathan, Stephen A.; Leckie, R. Mark
Author Affiliation(s): Primary:
University of Massachusetts at Amherst, Department of Geosciences, Amherst, MA, United States
Volume Title: 2009 AAPG annual convention & exhibition; abstracts volume
Source: Abstracts: Annual Meeting - American Association of Petroleum Geologists, Vol.2009; AAPG 2009 annual convention & exhibition, Denver, CO, June 7-10, 2009. Publisher: American Association of Petroleum Geologists and Society for Sedimentary Geology, Tulsa, OK, United States
Note: In English
Summary: During the middle to late Miocene, changes in tectonics and sea level profoundly impacted both global climate and ocean circulation. This study uses planktic foraminifera to examine the interplay between the constriction of the Indonesian Seaway, the uplift of the Himalaya-Tibetan Plateau, and changes in sea level, and how they irrevocably affected the South China Sea (SCS) and the western equatorial Pacific for the interval ∼13 - 6 Ma. The SCS records the onset of a proto-warm pool after ∼12 Ma, as also observed in the western equatorial Pacific [at Ontong Java Plateau (OJP), Ocean Drilling Program (ODP) Site 806]. The eustatic changes that contributed to the initiation of a proto-warm pool may have transformed the SCS into a semi-enclosed basin, or a basin with greatly restricted flows across the Sunda Shelf. This configuration of the SCS may have lasted until sea level began to rise after ∼9.6 Ma or later, as noted by a decrease in the δ18O gradient between thermocline and mixed layer taxa. At ∼8.5 Ma, an abrupt increase in the relative abundance of thermocline taxa and changes in the carbon and oxygen isotope gradients may signal increased productivity or increased seasonality associated with intensification of the East Asian monsoon. For the northern SCS (ODP Site 1146) the non-warm pool state may have lasted until the end of the record (∼5.6 Ma) while in the southern SCS (ODP Site 1143) the record is less conclusive. Both sites display low planktic foraminiferal δ18O values relative to the western equatorial Pacific (OJP), suggesting that the SCS was significantly influenced by fluvial input.
Year of Publication: 2009
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; C-13/C-12; Carbon; Cenozoic; Equatorial Pacific; Foraminifera; Invertebrates; Isotope ratios; Isotopes; Leg 130; Microfossils; Middle Miocene; Miocene; Neogene; North Pacific; Northwest Pacific; O-18/O-16; ODP Site 806; Ocean Drilling Program; Ontong Java Plateau; Oxygen; Pacific Ocean; Paleo-oceanography; Paleogeography; Planktonic taxa; Plate tectonics; Protists; South China Sea; Stable isotopes; Tertiary; Upper Miocene; West Pacific
Coordinates: N001906 N001907 E1592142 E1592140
Record ID: 2012099914
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States