Abstract Delineating the climatic boundary (i.e., of precipitation and temperature) in the northern Tibetan Plateau and along its margins is important for understanding the dynamics of global atmospheric circulation and the processes of dust production in central Asia. To date, however, meteorological data are scarce for this vast region, which limits our understanding of regional climatic patterns and past climatic changes in Eurasia. In the present study, we use a synthesis of both new and published rock magnetic data from the late Pliocene, the last glacial-interglacial cycle, and modern eolian sediments to identify the climatic boundary in the northern Tibetan Plateau and its adjacent areas. The results demonstrate that eolian deposits under different environmental scenarios exhibit a clear contrast in the type and grain-size distribution of magnetic minerals. With the transition from humid to arid climatic regimes, a gradual shift from magnetic minerals of predominantly pedogenic origin to predominantly detrital origin can be observed in the surface soils. The spatial and altitudinal variations in the magnetic properties of surface soils reveal a distinct boundary of pedogenic intensity in the eastern Qilian Mountains, the western Pamir Plateau and the northern Tianshan Mountains. The inferred variations in pedogenic intensity, combined with analysis of the available meteorological data, demonstrate that the pedogenic boundary represents a critical climatic boundary between sub-humid to semi-arid and arid regions in the northern Tibetan Plateau and the adjacent regions. Stronger pedogenesis occurs in surface soils at higher altitudes on the windward side of the major mountains of the northern Tibetan Plateau, supporting the conclusion that precipitation rather than temperature exerts the dominant effect on the magnetic enhancement of surface soils. In addition, a comparison of several late Pliocene-Pleistocene and last glacial-interglacial loess-red clay sequences suggests that the modern spatial pattern of the climatic gradients in the northeastern Tibetan Plateau and the adjacent regions has been maintained since at least the late Pliocene or early Pleistocene. Moreover, the results demonstrate that during the warm and humid interglacial periods, a steepened rainfall gradient occurred in the northern Tibetan Plateau and its adjacent regions. In the future, detailed rock magnetic investigations of eolian deposits or surface soils could provide new insights into the dynamics of atmospheric circulation and the natural boundary conditions for paleoclimate modeling in the northern Tibetan Plateau.

中文翻译：

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青藏高原北部及邻近地区风成沉积物磁特性的空间和高度变化：对气候边界划定的意义

摘要 描绘青藏高原北部及其边缘的气候边界（即降水和温度）对于理解全球大气环流动力学和中亚沙尘产生过程具有重要意义。然而，迄今为止，这一广阔地区的气象数据很少，这限制了我们对欧亚大陆区域气候模式和过去气候变化的理解。在本研究中，我们综合使用来自晚上新世、最后一次冰期-间冰期循环和现代风成沉积物的新的和已发表的岩石磁学数据来确定青藏高原北部及其邻近地区的气候边界。结果表明，不同环境情景下的风成沉积物在磁性矿物的类型和粒度分布上表现出明显的对比。随着从潮湿气候向干旱气候的转变，可以在表层土壤中观察到从主要成土成因的磁性矿物逐渐转变为主要成土成因的磁性矿物。表层土壤磁性的空间和海拔变化揭示了祁连山脉东部、帕米尔高原西部和天山北部的成土强度明显的边界。推断的成土强度变化，结合对现有气象数据的分析，表明成土边界代表了青藏高原北部及邻近地区半湿润至半干旱和干旱地区之间的临界气候边界。青藏高原北部主要山脉迎风侧较高海拔的表层土壤发生较强的成土作用，支持了降水而不是温度对表层土壤的磁增强起主导作用的结论。此外，对几个晚上新世-更新世和末次冰期-间冰期黄土-红粘土序列的比较表明，青藏高原东北部及邻近地区气候梯度的现代空间格局至少自上新世晚期或早更新世。而且，结果表明，在暖湿间冰期，青藏高原北部及邻近地区出现了陡峭的降雨梯度。未来，对风成沉积物或表层土壤进行详细的岩石磁学研究可以为青藏高原北部大气环流动力学和古气候模拟的自然边界条件提供新的见解。