East Asian monsoon intensification promoted weathering of the magnesium-rich southern China upper crust and its global significance

Abstract

The Oligocene-Miocene boundary climatic reorganization linked to the northward advance of the East Asian monsoon in subtropical China is a potentially important but poorly constrained atmospheric CO2 sink. Here, we performed a first-order estimate of the difference in CO2 consumption induced by silicate chemical weathering and organic carbon burial in subtropical China related to this monsoon advance. The results highlight the significant role of weathering of the Mg-rich upper continental crust in East China that would contribute significantly to the rise in the Mg content of the ocean during the Neogene. Our results show that an increase in CO2 consumption by silicate weathering varies between ~1% and 15% of the current global continental silicate sink with an ~60% contribution of Mg-silicate weathering since the late Oligocene but a negligible increase in the global organic carbon burial (<3.5%). The carbon impact of the northward advance of the East Asian monsoon is therefore significant but strongly related to the Mg-rich nature of the crust affected by such climatic change. Further modelling work indicates that the uplift of the northern Tibetan Plateau plays a key role in this monsoon advance. Our study thus suggests that the uplift of the Himalayas-Tibetan Plateau can lead to indirect modification of the carbon cycle and the global climate by changing the regional hydrological cycle in areas of East Asia that are tectonically inactive in addition to the direct impact of high erosion and organic carbon burial along the orogenic belt in South Asia.

Trends and Transitions in Silicate Weathering in the Asian Interior (NE Tibet) Since 53 Ma

“…This Asian climate reorganization is assumed to be caused by Tibetan Plateau uplift and the retreat of the Para-Tethys sea (e.g., Ramstein et al, 1997;Fluteau et al, 1999;Zhang et al, 2007a, Zhang et al, 2007b, during which the retreat of the Para-Tethys sea could be regarded as a far-field effect of the India-Asia collision. Such tectonics-driven northward migration of the intensified EASM was considered to have promoted increased rainfall in subtropical China and the NE Tibetan Plateau, thus facilitating silicate weathering (Yang et al, 2021d). The Middle Miocene was another period of EASM strengthening, which may have been caused by Tibetan Plateau uplift (Liu and Yin, 2002;Zhang R. et al, 2015) or global warming (Westerhold et al, 2020).…”

Neogene drainage reorganization of Longzhong Basin driven by growth of the northeastern Tibetan Plateau: A Sr isotope hydrological perspective

“…The uplift of the Tibetan Plateau has profound impacts on Asian and global climates (e.g., An et al., 2001; France‐Lanord & Derry, 1997; Guo et al., 2021; Raymo & Ruddiman, 1992; Wu et al., 2022), as well as Asian continent drainage patterns (e.g., Clark et al., 2004; Clift & Blusztajn, 2005; Gupta, 1997; Robinson et al., 2014; Zhao et al., 2021; Zheng et al., 2013). Drainage evolution across the Tibetan Plateau and its surroundings not only controls the drainage source‐to‐sink system but also influences the erosion and weathering regime; the former provides insight into regional topography and environmental reconstructions (Allen, 2017), and the latter is crucial to understanding the uplift‐induced Cenozoic global cooling through atmospheric CO 2 consumption (France‐Lanord & Derry, 1997; Raymo & Ruddiman, 1992; Yang, Galy, Fang, France‐Lanord, et al., 2021). However, the evolution of major drainage basins around the Tibetan Plateau is less understood, which hinders the elucidation of the Tibetan Plateau uplift and its environmental impacts.…”