Links between geochemical weathering on the NE Tibetan Plateau and global climate change since the Last Deglacial

Abstract

The links between chemical weathering on a continental scale and climate have long been a central issue in Earth science. However, the limited knowledge of the interconnections between weathering and climate impedes our understanding of its role in the evolution of the Earth’s climate. The Tibetan Plateau is the world’s highest and largest plateau and the source of water resources for nearly half of the world’s population, it has become a key area for paleoclimate research due to its influence on the atmospheric circulation system and sensitivity to climate change. Herein, we present a major and trace elements-based record of chemical weathering from sediments in the Hurleg Lake, northeastern Tibetan Plateau, over the past 14.1 cal kyr BP. As showed in elements deduced indexes, Hurleg Lake sediments were mainly originated from felsic rocks. Besides, the sediments source remained largely unchanged in the last 14.1 cal kyr BP and the sediments underwent only minimal recycling, and not affected by diagenesis and metasomatism, thus preserving a record of the chemical weathering intensity in the lake catchment. The chemical weathering indexes presented consistent trends and were in good agreement with the variation of δ13Ccarb in authigenic carbonate derived from the same sequence. Chemical weathering intensified during 14.1 ∼ 12.5, 11.1 ∼ 8.7, 7.2 ∼ 4.8 cal kyr BP, and after 3.5 cal kyr BP, when the climate was warm and/or humid, but weakened in cold-dry intervals of 12.5 ∼ 11.1, 8.7 ∼ 7.2, and 4.8 ∼ 3.5 cal kyr BP. The wet intervals correspond to periods of intensification of the East Asian Summer Monsoon (EASM) or Westerlies. Furthermore, the climate changes in the study area are also typically linked to high- and low-latitude factors that influence global climate conditions, such as insolation changes, the North Atlantic ice-rafting event, and Atlantic Intertropical Convergence Zone (ITCZ) migrations. The “unusual” cold-dry episode in the 4.8 ∼ 3.5 cal kyr BP possibly dominated by both Westerlies and EASM, the result supports the point that both high and low latitude feedbacks played an important role in modulating Hurleg Lake clod-dry climate during 4.8 to 3.5 cal kyr BP. Our records suggest that the climate evolution on the northeastern Tibetan Plateau response to global climate change sensitively, and the possibility that variabilities in the ITCZ might be instrumental in understanding high to low-latitude climate linkages on a global scale.