A high-resolution clay mineralogical record in the northern South China Sea since the Last Glacial Maximum, and its time series provenance analysis

Abstract

High-resolution clay mineralogical analysis of Core MD05-2904 in the northern South China Sea (SCS) covering the period since the Last Glacial Maximum shows that illite (29%-48%), smectite (14%-45%), chlorite (17%-28%), and minor kaolinite (6%-14%) comprise the clay mineral assemblage, and that time series variation does not present glacial-interglacial cyclicity. Provenance analysis indicates three end-member sources: almost all smectite derives from Luzon, all kaolinite is sourced from the Pearl River, and illite and chlorite originate from both the Pearl River and Taiwan. By comparing clay mineral compositions in surface sediments from the three major source areas and of the SCS, we reconstructed a time series of clay mineral contribution from the major provenances to the northern slope of the SCS using the linear separation method for illite crystallinity. There were three stages of provenance change. (1) During 24.1-17.5 ka BP, contributions from Taiwan and Luzon were similar (30%-40%), while that from the Pearl River was only 25%. (2) During 17.5-14.0 ka BP, the contribution from Luzon decreased rapidly to 20%-25%, while that from Taiwan increased to 35% from an average of 25% at 18 ka BP, and that from the Pearl River increased largely to 40%. (3) During the Holocene, differences in contributions from the three major provenances increased: the contribution from Luzon increased slightly and then remained at 27%-35%, that from Taiwan increased rapidly and then remained at 55%-60%, and that from the Pearl River decreased to 15%. The change in clay mineral contributions from different provenances is influenced mainly by clay mineral production, monsoon rainfall denudation, oceanic current transport, and sea-level change.clay minerals, illite crystallinity, provenance, Last Glacial Maximum, sea level change, East Asian monsoon, South China Sea Citation:Liu Z F, Li X J, Colin C, et al. A high-resolution clay mineralogical record in the northern South China Sea since the Last Glacial Maximum, and its time series provenance analysis.

Contrasting Fates of Petrogenic and Biospheric Carbon in the South China Sea

“…The negligible input of terrestrial biospheric OC in the modern SCS may contrast sharply to glacial periods when lower sea level permitted greater terrigenous export into the OC into the deep SCS (Zhao et al, ). For example, increases in kaolinite contributions during the most recent glacial period mark heightened contributions from the Chinese mainland (Liu, Li, et al, ) that likely coincide with elevated pedogenic OC contributions, which evaded trapping on the shelf and margin areas. Nevertheless, it is evident that terrestrial OC in deep‐sea sediments, even within the tropics, may be predominantly petrogenic in origin.…”

Clay mineralogical and geochemical proxies of the East Asian summer monsoon evolution in the South China Sea during Late Quaternary

“…The underlying mechanism was proposed to be either the surface circulation related to monsoon winds 26 or the balance of chemical weathering versus physical erosion on land 25 . However, high-resolution clay mineral records do not always present such glacial-interglacial cyclicity 28 29 . Indeed, a predominant control by precession is observed in the variations of smectite/(illite + chlorite) ratio at ODP Site 1145, which is probably induced by changes in weathering and transport 28 .…”

“…Indeed, a predominant control by precession is observed in the variations of smectite/(illite + chlorite) ratio at ODP Site 1145, which is probably induced by changes in weathering and transport 28 . The clay mineralogical record since the last glacial maximum revealed the complexity of terrigenous input from surrounding drainage systems and transport processes 29 . The mechanism that links the EASM evolution and the sediment composition remains discussible.…”

Early interglacial carbonate-dilution events in the South China Sea: Implications for strengthened typhoon activities over subtropical East Asia

“…8d). This observation is supported by the illite crystallinity, which suggests relative stable contribution of clay flux from Taiwan, the Pearl River and Luzon to the core location of MD05-2904 throughout the Holocene (Liu Z. et al, 2010b). Moreover, the Sr and Nd isotopic records of ODP1144 together also point to a dominant Taiwan provenance for the fine-and coarse-grained terrigenous sediments accumulated during the low CaCO 3 % event as well as other time periods of the Holocene (Hu et al, 2012).…”