Chemical weathering, physical erosion and provenance record of southwestern of the South China Sea since middle Miocene

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doi: 10.1130/abs/2016SC-273022
Author(s): Liu, Chang; Clift, Peter D.; Murray, Richard W.; Ireland, Thomas; Blusztajn, Jerzy S.
Author Affiliation(s): Primary:
Louisiana State University, Department of Geology and Geophysics, Baton Rouge, LA, United States
Other:
Boston University, United States
Volume Title: Geological Society of America, South-Central Section, 50th annual meeting
Source: Abstracts with Programs - Geological Society of America, 48(1); Geological Society of America, South-Central Section, 50th annual meeting, Baton Rouge, LA, March 21-22, 2016. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: The sediment in the SW South China Sea potentially records the history of erosion, weathering and drainage capture in a tectonically active part of SE Asia, heavily influenced by the monsoon and by the India-Eurasia collision. We analyzed sediment samples from International Ocean Discovery Program (IODP) Site U1433 in the SW South China Sea. Major and trace element compositions, clay mineralogy, Sr and Nd isotope data provide a record of chemical weathering, physical erosion intensity and evolving provenance since 17 Ma, following the end of seafloor spreading. Smectite/(illite+chlorite) and smectite/kaolinite have variable and high values before ∼8 Ma after which they are most low and stable. The Chemical Index of Alteration (CIA) increases sharply after 8 Ma, consistent with the clays. 87Sr/86Sr also changes at 8 Ma suggestive of more alteration but largely driven by a provenance change indicated by Nd isotopes. The Mekong river became the dominant sediment source to Site U1433. Our combined data set implies a change in sediment source to Site U1433 from Borneo to the Mekong especially at 8 Ma. We suggest that this indicates the establishment of the Mekong Delta in its present position, driven by a switch from the Gulf of Thailand, possibly linked to uplift of Central Highlands of Vietnam.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Alkaline earth metals; Cenozoic; Chemical composition; Chemical weathering; Erosion; Expedition 349; IODP Site U1433; International Ocean Discovery Program; Isotope ratios; Isotopes; Marine sediments; Metals; Miocene; Neodymium; Neogene; North Pacific; Northwest Pacific; Pacific Ocean; Pleistocene; Pliocene; Provenance; Quaternary; Rare earths; Sediments; South China Sea; Sr-87/Sr-86; Stable isotopes; Strontium; Tertiary; Weathering; West Pacific
Coordinates: N125508 N125508 E1150251 E1150250
Record ID: 2016076400
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