第七届青年地学论坛

Asia contains more than half the world’s population, and their lives are significantly related to summer monsoon moisture supply. Here, we investigate features and dynamics of late Pleistocene–middle Holocene Asian summer monsoon variability in the Nihewan Basin, North China, which was a critical home for early humans in East Asia throughout the Quaternary. We present new mineral magnetic records between 16 and 5 ka from the Yujiagou archeological site in the northern Nihewan Basin, which contains more than 40,000 stone tools, 2 pottery pieces, and 19,686 mammal fossils. Magnetic properties of the Yujiagou section are dominated by pedogenic fine-grained magnetite/maghemite concentration, which ranges from superparamagnetic/single domain up to fine pseudo-single domain sizes. We use multiple environmental magnetic proxies, which measure pedogenic magnetite/maghemite concentration, to document that summer monsoon precipitation was low before ~14.5 ka and high during the Bölling-Allerød warm period (14.5–12.8 ka), and shifted to low values at the onset of the Young Dryas cold period ~12.4 ka, followed by a sustained long-term increasing trend from 12.4 to 5 ka. We relate these monsoon precipitation changes to Atlantic Meridional Overturning Circulation variability, which modulated North Hemisphere temperatures and displacements of Inter-Tropical Convergence Zone and Walker circulation in the Pacific Ocean. The observed large-amplitude deglacial Asian monsoon changes may have played a role in several key evolutionary changes in Asia implicated by the Yujiagou archeological evidence, including Paleolithic to Neolithic culture transition, Asian pottery development, and early human dispersals from Asia to America.

环境磁学,东亚夏季风,泥河湾盆地,晚更新世,早全新世