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Intensification of the Asian monsoon and a chemical weathering event in the late Miocene-early Pliocene; implications for late Neogene climate change

Gabriel M. Filippelli
Intensification of the Asian monsoon and a chemical weathering event in the late Miocene-early Pliocene; implications for late Neogene climate change
Geology (Boulder) (January 1997) 25 (1): 27-30

Abstract

Several sedimentary, geochemical, and isotopic records indicate that the hypothesized intensification of the Asian monsoon at about 8 Ma triggered a physical and chemical weathering event in the Himalayan-Tibetan Plateau. Records of sediment input and clay composition from the northern Indian Ocean reveal clear weathering changes in the plateau at this time, and Ge/Si ratios of opaline silica as well as biogenic sedimentation rates indicate that increased dissolved element fluxes from this weathering event had an oceanwide effect. It is likely that weathering intensity also increased in the Andes and Amazon Basin in this interval as well. Perhaps the most important impact of this weathering event was to increase the net flux of the biolimiting nutrient phosphorus to the ocean, as evidenced by a peak in phosphorus accumulation rates at this time. The temporary increase in nutrient inputs to the ocean triggered increased oceanic productivity and organic carbon burial (recorded in carbon isotopic records and paleooxygen concentrations). The net result of this weathering event may have been an increase in the rate of drawdown of atmospheric CO (sub 2) through the late Miocene-early Pliocene, via direct silicate weathering reactions and increased burial of organic carbon in the ocean. This increased rate of atmospheric CO (sub 2) drawdown may have destabilized the climate system by the late Pliocene, thus initiating a period of intense cooling and ice buildup leading to the present.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 25
Serial Issue: 1
Title: Intensification of the Asian monsoon and a chemical weathering event in the late Miocene-early Pliocene; implications for late Neogene climate change
Affiliation: Indiana University-Purdue University at Indianapolis, Department of Geology, Indianapolis, IN, United States
Pages: 27-30
Published: 199701
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 44
Accession Number: 1997-017069
Categories: StratigraphyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
N20°00'00" - N53°00'00", E74°00'00" - E135°00'00"
N27°00'00" - N37°00'00", E72°00'00" - E97°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199706
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