Millennial to orbital scale Indian summer monsoon evolution inferred from grain size end-members in Tengchongbeihai wetland, southwestern China

• Published in: Quaternary science reviews 2024-06, Vol.334, p.108723, Article 108723
• Main Authors: Ning, Dongliang, Xiao, Xiayun, Tang, Suqin, Xu, Yuchen, Kuai, Xiang, Ge, Ying, Zheng, Jianan, Cheng, Longjuan, Wan, Dejun, Jiang, Qingfeng, Li, Yanling
• Format: Article
• Language: English
• Subjects: End-member; Grain size; Indian summer monsoon; Paleoclimatology; Wetland
• ISSN: 0277-3791; 1873-457X
• DOI: 10.1016/j.quascirev.2024.108723

Understanding the Indian summer monsoon (ISM) variabilities under different climatic constraints on various timescales is crucial for socio-economic stabilization within the ongoing warming globe. However, aside from stalagmite records, very few terrestrial paleoclimate archives have been used to explore the last glacial ISM characteristic, which limits our understanding of the ISM natural behaviors and their underlying mechanisms on longer timescales. Here, we present a grain size end-member analysis for Tengchongbeihai wetland sediments from southwestern China to investigate the paleo-hydroclimate changes since the late MIS3. The overall low fine silt content before ∼19 cal ka BP resulted from weak catchment erosion indicating weak ISM during cold glacial while the increasing trend thereafter indicates the ISM strengthened during the last deglaciation and Holocene. Such an orbital ISM evolution resembles to the insolation gradient between 25°N and 25°S during the boreal summer periods, which implies that the transequatorial insolation difference could be an alternative explanation for the orbital scale low latitude hydroclimate changes. The remarkable peaks of coarse component around ∼9, 12, 19, 26, 32, 37 and 42 cal ka BP were related to significant water level descending indicating the millennial ISM collapse corresponding to the YD and Heinrich events. However, the absence of sawtooth feature as the NGRIP δ18O and the well correspondence to the Indian Ocean sea surface temperatures (SSTs) of the ISM collapses evidence the modulation of low latitude forcing on the North Atlantic climate effects on the millennial scale hydroclimate variabilities. •Millennial to orbital ISM changes over 46 ka was studied using a wetland sediment.•The trans-equatorial insolation gradient controlled orbital ISM evolution.•The millennial ISM fluctuations tele-connected to the North Atlantic instabilities.•Indian Ocean SSTs modulated the relation between ISM and North Atlantic climate.