Temperature Control on Silicate Weathering Intensity and Evolution of the Neogene East Asian Summer Monsoon

Abstract

Accurately reconstructing the evolution of the Asian monsoon is predicated on understanding the impact of temperature, precipitation, and tectonic paleogeography on silicate weathering proxies over million year timescales. We find that decreasing trends in chemical weathering proxies in both the northern and southern Tibetan Plateau match those from benthic oxygen isotope and sea surface temperature stacks since the late Miocene. In contrast, a synthesis of magnetic parameter‐based records and marine clastic flux records reveals stronger monsoon precipitation during both the warm middle Miocene and cool late Miocene, supporting model simulations showing that both paleogeography and atmospheric CO2 content are important in controlling the summer monsoon. This trend of increasing monsoon precipitation contrasts with the record of decreasing chemical weathering, suggesting that chemical weathering proxies are mainly regulated by temperature at million year timescales, rather than precipitation. These findings clarify reconstructions of the Cenozoic evolution of the East Asian summer monsoon.

Diachronous Growth of the Northern Tibetan Plateau Derived From Flexural Modeling

“…All these deductions are based on the indirect knowledge of the deformation history of the mountain belts and source to sink analysis. Paleotopography of the Tibetan plateau is also considered as an important factor that controlled the establishment of the Asian monsoon by changing the atmospheric circulation (Clift et al., 2008; Licht et al., 2014; Molnar et al., 1993; Xie et al., 2019), although there is growing appreciation for monsoon intensification driven by atmospheric CO 2 concentrations and other factors (Nie et al., 2018; Ren et al., 2020). Therefore, there is an urgent need for independent paleoelevation proxies for the northern Tibetan plateau.…”

Topographic growth of the northeastern Tibetan Plateau during the middle‐late Miocene: Insights from integrated provenance analysis in the NE Qaidam Basin

“…Chemical weathering is expected to increase Al 2 O 3 /SiO 2 ratios through the breakdown of feldspar and in the generation of clays (Nesbitt & Markovics, 1997). In the northern Qaidam Basin, the positive shift of oxygen isotopes during 12-10 Ma and reduced chemical weathering index (CIA) during 14-8 Ma (Bao et al, 2019;Ren et al, 2020) O 3 and TFe 2 O 3 and TFe 2 O 3 / SiO 2 ratios share similar trends with Al 2 O 3 /SiO 2 ratios (Figure S2 in the Supporting Information), less likely caused by chemical and physical weathering (Garzanti et al, 2015).…”

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

“…This sedimentary archive can provide a continuous record of the response of silicate weathering to the weak uplift of the NE Tibetan Plateau during the Paleogene and rapid uplift during the Neogene (Tapponnier et al, 2001;Yang et al, 2021a). During the past decade, multiple long-term records of silicate weathering history have been acquired from the NE Tibetan Plateau and the adjacent Chinse Loess Plateau, based on element ratios (Song et al, 2013;Sayem et al, 2018;Bao et al, 2019;Ren et al, 2020) and clay minerals (Zhang and Guo, 2014;Sun et al, 2015;Zhang C. et al, 2015;Fang et al, 2016a;Song B. et al, 2018;Ye et al, 2018;Fang et al, 2019b;Liu et al, 2019;Yang et al, 2019;Liu et al, 2020;Ye et al, 2020;Yang et al, 2021b;Zhao et al, 2021). However, the available silicate weathering records from the region are fragmentary because they are derived from diverse time intervals from multiple sections/basins, and they lack comparability due to the use of different elements and minerals.…”