Open AccessMiocene climate change on the Chinese Loess Plateau: Possible links to the growth of the northern Tibetan Plateau and global cooling
Author(s) -
Sun Youbin,
Ma Long,
Bloemendal Jan,
Clemens Steven,
Qiang Xiaoke,
An Zhisheng
Publication year - 2015
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2015gc005750
Subject(s) - geology , plateau (mathematics) , east asian monsoon , monsoon , global cooling , late miocene , cenozoic , climate change , paleoclimatology , climatology , aridification , paleontology , physical geography , earth science , arid , oceanography , structural basin , geography , mathematical analysis , mathematics
The evolution of the Asian monsoon‐arid environmental system during the Cenozoic was closely related to the growth of the Himalayan‐Tibetan Plateau and global climate change. However, due to inconsistencies in paleoclimatic reconstructions and to various constraints on the timing of the growth of the Tibetan Plateau, the relative impacts of regional uplift and global cooling on Asian climate change remain controversial. Here we investigate the mineralogical composition of a Miocene Red Clay deposit on the western Chinese Loess Plateau in order to infer changes in chemical weathering and monsoon intensity. Variations of four mineralogical ratios (chlorite/quartz, illite/quartz, calcite/quartz, and protodolomite/quartz) reveal that the summer monsoon intensity was relatively strong during the early Miocene (23.5–18.5 Ma), weakened gradually until ∼9.5 Ma, and strengthened again in the late Miocene. We synthesized previously published thermochronological data from the northeastern Tibetan Plateau and surrounding mountains, and the results suggest that two phases of the rapid growth of northern Tibet occurred around 24–17 and 13–7 Ma. Comparison of paleoclimatic proxies and thermochronological data suggests that the gradual weakening of the summer monsoon intensity from 18.5 to 9.5 Ma paralleled global cooling, whereas two intervals of strengthened monsoon in the early and late Miocene were possibly related to the rapid growth of northern Tibet. Our combination of paleoenvironmental proxies and thermochronological data reveals possible links between Miocene Asian monsoon evolution, phased growth of the Tibetan Plateau, and global climate change, and confirms the interconnection of geodynamic and atmospheric processes in the geological past.