The middle Eocene to early Miocene integrated sedimentary record in the Qaidam Basin and its implications for paleoclimate and early Tibetan Plateau uplift
The middle Eocene to early Miocene integrated sedimentary record in the Qaidam Basin and its implications for paleoclimate and early Tibetan Plateau uplift
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DOI：
10.1139/cjes-2012-0048
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发表时间：
2013-03
影响因子：
1.4
通讯作者：
B. Song;Kexin Zhang;Jingfang Lu;Chaowen Wang;Yadong Xu
中科院分区：
文献类型：
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作者：
B. Song;Kexin Zhang;Jingfang Lu;Chaowen Wang;Yadong Xu
对柴达木盆地东北部大红沟剖面的全岩地球化学、粘土矿物、沉积颜色和孢粉进行了详细的分析，结果表明，源区在始新世中期(∼48.5~40.5 Ma)经历了强烈的风化作用，表明其处于温暖潮湿的环境。源区化学风化程度的明显减弱始于∼40.5 Ma，这与沉积序列红度的明显降低和孢粉记录中嗜热元素的消失相一致。这一40.5 Ma的降温事件证明了中亚干旱化的加剧，这可能是由于西藏中南部高海拔地区在始新世晚期从中亚撤退，减少了水分向柴达木盆地的输送。
Detailed analysis of whole-rock geochemistry, clay minerals, sedimentary color, and pollen in the Dahonggou section, northeast of the Qaidam Basin, are investigated, and the results suggest an intense weathering in the source area during the middle Eocene (∼48.5–40.5 Ma), indicating a warm and humid condition. The distinct decrease of chemical weathering degree in source regions began at ∼40.5 Ma, which is in agreement with the distinct decrease in redness of sedimentary sequences and the disappearance of thermophilic elements in pollen records. This 40.5 Ma cooling event extent demonstrated evidence for an intensification of central Asian aridification, which could be attributed to attainment of high elevations in southern-central Tibet and retreat of the Paratethys from central Asia in the late Eocene, reducing moisture transport to the Qaidam Basin.