| 青藏高原东北缘西宁黄土的磁学记录及其环境意义 |
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| 关键词:Tibetan Plateau uplift Xining loess environmental magnetism East Asian monsoon Asian interior aridification |
| 基金项目:国家自然科学基金项目(编号: 42104080; 42474101; 42530304; 42130720)；中国地质科学院地质力学研究所基本科研业务费项目(编号: DZLXJK202404) |
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| Magnetic Properties of the Xining Loess on the Northeastern Tibetan Plateau and Their Environmental Implications |
| The uplift of the Tibetan Plateau has exerted profound impacts on the evolution of the Asian monsoon. However, due to the scarcity of continuous Quaternary sedimentary records across the plateau and its margins, disentangling the respective signals of solar radiation, global ice volume variations, and Tibetan Plateau uplift in driving East Asian monsoon evolution remains highly contentious. The 260-m-thick Xining loess–paleosol sequence on the northeastern Tibetan Plateau (NETP) provides an exceptional archive to resolve the contribution of NETP to East Asian monsoon dynamics. This study investigates a high-quality drill core from the Dadunling section in Xining, employing high-resolution granulometric and multi-proxy magnetic climatic analyses, yielding the following key findings: (1) Detailed rock magnetic analyses reveal that pedogenically derived fine-grained ferrimagnetic minerals dominate magnetic enhancement in paleosol layers, while the gradual increase in saturation isothermal remanent magnetization in overlying loess units reflects enhanced inputs of detrital coarse-grained ferrimagnetic minerals. (2) Integrated bulk grain-size and magnetic parameter records demonstrate that the intensification of East Asian winter monsoon and long-term aridification trends documented in the Xining loess during 1.3–0.2 Ma were markedly more pronounced than those of typical loess on the Chinese Loess Plateau. This verifies the critical role of Tibetan Plateau uplift in amplifying East Asian monsoon circulation and promoting Asian interior aridification against the backdrop of global cooling. (3) The negative relationship between physical erosion and chemical weathering in the NETP does not conflict with the widely accepted uplift-weathering hypothesis but instead highlights a strong positive feedback mechanism involving climate, silicate weathering, and tectonic activity in this dynamic region. These results offer strong evidence that the NETP, along with its surrounding topography, has significantly impacted the irreversible increase in aridity within Asia interior. |
| SHENG Mei,LI Zongyao,TONG Yabo,JIANG Kai,YI Shiyu,HU Ke,WANG Xisheng.2025.Magnetic Properties of the Xining Loess on the Northeastern Tibetan Plateau and Their Environmental Implications[J].Acta Geoscientica Sinica,46(6):1082-1094. |
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