Late Oligocene to early Miocene humidity change recorded in terrestrial sequences in the Ili Basin (south‐eastern Kazakhstan, Central Asia)
Late Oligocene to early Miocene humidity change recorded in terrestrial sequences in the Ili Basin (south‐eastern Kazakhstan, Central Asia)
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DOI：
10.1111/sed.12390
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发表时间：
2018-02
期刊：
影响因子：
3.5
通讯作者：
Alexandra Hellwig;S. Voigt;A. Mulch;Konstantin Frisch;Alexander Bartenstein;J. Pross;A. Gerdes;
中科院分区：
文献类型：
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作者：
Alexandra Hellwig;S. Voigt;A. Mulch;Konstantin Frisch;Alexander Bartenstein;J. Pross;A. Gerdes;
造山地表隆起、副特提斯海退缩、大气水分输送变化和全球变冷的综合影响导致中亚干旱化加剧，是北半球最突出的新生代气候变化事件之一。因此，破译中亚水文学的区域长期模式是理解北半球中纬度干旱在全球水文系统中的作用的关键要素。本研究基于稳定同位素、元素地球化学和冲积、河流和成土矿床的激光烧蚀铀-铅地质年代学，描述了哈萨克斯坦东南部渐新世晚期和中新世早期之间的长期古环境条件。沉积相和地球化学风化指数表明，天山腹地地形降雨量增加导致地表和地下水排放增加。相比之下，成土稳定同位素数据和粘土矿物中镁固定率的升高反映了由于长期干旱而导致包气带蒸发率增加。本研究认为，渐新世-中新世过渡期间天山山脉明显的地表隆起促进了区域性地形降水的增加和河流排放系统的发展。
Enhanced aridification of Central Asia driven by the combined effects of orogenic surface uplift, Paratethys retreat, changes in atmospheric moisture transport and global cooling is one of the most prominent Cenozoic climate change events of the Northern Hemisphere. Deciphering regional long‐term patterns of Central Asian hydrology is, therefore, a key element in understanding the role of Northern Hemisphere mid‐latitude drying in the global hydrological system. This study characterizes long‐term palaeoenvironmental conditions between the late Oligocene and early Miocene in south‐eastern Kazakhstan based on stable isotopes, elemental geochemistry and laser ablation uranium–lead geochronology from alluvial, fluvial and pedogenic deposits. Sedimentary facies and geochemical weathering indices suggest an increased surface and groundwater discharge fed by orographically enhanced precipitation in the Tien Shan hinterland. In contrast, pedogenic stable isotope data and elevated rates of magnesium fixation in clay minerals mirror enhanced rates of evaporation in the vadose zone due to protracted aridification. This study posits that pronounced surface uplift of the Tien Shan Mountains during the Oligocene–Miocene transition promoted regionally increased orographic precipitation and the development of fluvial discharge systems.