Abstract

The relationship between silicate weathering, Tibetan Plateau uplift, and global cooling during the Cenozoic provides a valuable case study for understanding the interaction of tectonics and climate. The Tibetan Plateau uplift is considered to have caused Cenozoic cooling via the atmospheric CO2 drawdown by increased silicate weathering. However, this hypothesis has been intensively debated over the past few decades due to the lack of complete silicate weathering records from the continental interior, which can directly track the effects of uplift on weathering. We provide the first complete long (past 53 Myr) continental silicate weathering record from the NE Tibetan Plateau, combined with a comprehensive analysis on its evolution pattern, critical transitions, and associated driving forces. The silicate weathering intensity in NE Tibet is characterized by a long-term Paleogene decrease, modulated by global cooling, and a Neogene increase that may be related to the East Asian summer monsoon (EASM) intensification. Three major system transitions in regional silicate weathering are identified at ∼26–23 Ma, ∼16 Ma and ∼8 Ma, which are linked to enhanced EASM forced primarily by tectonic uplift at these intervals, with some surbordinate influences from global climate at ∼16 Ma. We also capture an intensification of the 100-kyr cycle at ∼16 Ma and ∼8 Ma in the obtained silicate weathering record, which is in coincidence in time with the enhancement of the EASM. This might suggest some contribution of the Antarctic ice sheets on modulating the regional silicate weathering in the NE Tibetan Plateau on a timescale of 105–106 years, through its influences on the EASM as proposed by previous studies.

Highlights

  • Continental silicate weathering plays a critical role in stabilizing Earth’s climate system and habitability in the long term (Walker et al, 1981)

  • The silicate weathering intensity of the NE Tibetan Plateau is characterized by a long-term decrease during the Paleogene followed by a long-term enhancement during the Neogene

  • The ~26–23 Ma, ~16 Ma and ~8 Ma transitions identified in stacked silicate weathering intensity (SWI) record accompanied by the intensification of 100kyr eccentricity cycle at ~16 Ma and ~8 Ma in SWI record, are coincide with enhanced East Asian summer monsoon (EASM) at these intervals

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Summary

Introduction

Continental silicate weathering plays a critical role in stabilizing Earth’s climate system and habitability in the long term (Walker et al, 1981). The thick and continuous sequence of fluvial-lacustrine sediments in the NE Tibetan Plateau that have accumulated since the early Eocene is a rich source of information on the history of plateau uplift and climate change in the Asian interior (Fang et al, 2019a). 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). A long and continuous weathering record based on a consistent methodology is needed to elucidate the temporal evolution of regional silicate weathering and the controlling mechanisms

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