Publication Date:
2022-05-25
Description:
© The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Chemical Geology 451 (2017): 38-54, doi:10.1016/j.chemgeo.2017.01.008.
Description:
Sedimentary records in the southwestern South China Sea reflect the evolving erosion
and drainage systems that have operated in Southeast Asia during the Neogene. Analyses of the
chemistry and clay mineral composition of sediments from International Ocean Discovery
Program (IODP) Site U1433 allow us to examine these processes over the last 17 Ma. Sediment
older than 8 Ma was deposited relatively slowly. Sr and Nd isotopes indicate a variable
provenance with sequences of less and more altered material accompanied by strong changes in
the proportion of smectite. Sediment flux was probably from Indochina, as well as from a more
primitive volcanic source, most likely the Palawan ophiolite and/or Luzon. Sediments younger
than 8 Ma show a more stable Sr and Nd isotope character, indicating sources close to those seen
in the modern Mekong River, although with some influx from smaller rivers draining the
Indochina margin especially from 4–8 Ma. Our data are consistent with seismic estimates for an
onset to the Mekong in its present location after 8 Ma, following an avulsion from the Gulf of
Thailand.
Description:
Funding for this research was provided by U.S. Science Support Program and the
Charles T. McCord chair in petroleum geology at Louisiana State University.
Keywords:
Geochemistry
;
Clay minerals
;
Isotopes
;
Provenance
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
