Evolution and variability of the east Asian summer monsoon during the Pliocene; evidence from clay mineral records of the South China Sea

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doi: 10.1016/j.palaeo.2010.05.025
Author(s): Wan Shiming; Tian Jun; Steinke, Stephan; Li Anchun; Li Tiegang
Author Affiliation(s): Primary:
Chinese Academy of Sciences, Key Laboratory of Marine Geology and Environment, Qingdao, China
Tongji University, China
University of Bremen, Federal Republic of Germany
Volume Title: Palaeogeography, Palaeoclimatology, Palaeoecology
Source: Palaeogeography, Palaeoclimatology, Palaeoecology, 293(1-2), p.237-247. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0031-0182 CODEN: PPPYAB
Note: In English. 83 refs.; illus., incl. charts, sketch map
Summary: The late Pliocene is thought to be characterized by the simultaneous intensification of both the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM). However, the evolution of the EASM during the Pliocene remains still controversial and only little is known about the dynamics of the EASM during the Pliocene on orbital time scales. Here we use clay mineral assemblages in sediments from Ocean Drilling Program (ODP) Site 1143 in the southern South China Sea (SCS) to obtain proxy records of past changes in the EASM climate during the Pliocene. Provenance analysis suggests that illite, chlorite and kaolinite originated mainly from the Mekong River drainage area. Smectite was derived mainly from the Indonesian islands. The kaolinite/illite ratio and the chemical index of alteration (CIA) of siliciclastic sediments allowed us to reconstruct the history of chemical weathering and physical erosion of the Mekong River drainage area and thus, the evolution of the EASM during the Pliocene. Our clay minerals proxy data suggests a stronger EASM during the early Pliocene than during the late Pliocene. We propose that the long-term evolution of the EASM has been driven by global cooling rather than the uplift of the Tibetan Plateau. Spectral analysis of kaolinite/illite ratio displays a set of strong periodicities at 100ka, 30ka, 28ka, 25ka, and 22ka, with no clear obliquity-related signal. Our study suggests that the Pliocene EASM intensity on orbital time scales is not only controlled by the Northern Hemisphere summer insolation, but also strongly influenced by equatorial Pacific ENSO-like ocean-atmosphere dynamics. Abstract Copyright (2010) Elsevier, B.V.
Year of Publication: 2010
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Asia; Cenozoic; Chemical alteration index; Chemical weathering; Chlorite; Chlorite group; Clay mineralogy; Clay minerals; Climate change; Erosion; Illite; Kaolinite; Leg 184; Marine sediments; Mekong River; Monsoons; Neogene; North Pacific; Northwest Pacific; ODP Site 1143; Ocean Drilling Program; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Pliocene; Provenance; Reconstruction; Sediments; Sheet silicates; Silicates; Siliciclastics; Smectite; South China Sea; Tertiary; Upper Pliocene; Weathering; West Pacific
Coordinates: N092143 N092143 E1131707 E1131707
Record ID: 2010070266
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands