Cenozoic advance of the East Asian monsoon promoted weathering of the magnesium-rich southern China upper crust and its significance for global geochemical cycles of carbon and magnesium

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 consumption process. 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. 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 but a negligible increase in the global organic carbon burial (<3.5%) since the late Oligocene. The results highlight the significant role of weathering of the Mg-rich upper continental crust in East China that would also contribute significantly to the rise in the Mg content of the ocean. Our study thus suggests that the uplift of the Himalaya-Tibetan Plateau can lead to indirect modification of the global carbon and magnesium cycles by changing the regional hydrological cycle in areas of East Asia that are tectonically less active in addition to the well studied direct impact of high erosion-induced atmospheric CO₂ consumption along the orogenic belt in South Asia.