Carbon and oxygen isotopic constraints on paleoclimate and paleoelevation of the southwestern Qaidam basin, northern Tibetan Plateau
Carbon and oxygen isotopic constraints on paleoclimate and paleoelevation of the southwestern Qaidam basin, northern Tibetan Plateau
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DOI：
10.1016/j.gsf.2016.12.001
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发表时间：
2017-09
影响因子：
8.9
通讯作者：
Linlin Li;Chaodong Wu;C. Fan;Ji-Jun Li;Changhao Zhang
中科院分区：
文献类型：
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作者：
Linlin Li;Chaodong Wu;C. Fan;Ji-Jun Li;Changhao Zhang
x射线衍射和同位素研究表明，碳酸盐矿物主要为自生矿物，未保存碳酸盐碎屑和成岩作用的证据。同位素数据显示始新世中晚期δ 18o和δ 13c值波动较大，表明该区气候相对温暖、季节性干燥。渐新世δ 18o值与δ 13c值正相关，渐新世δ 13c值从始新世向渐新世正移，表明渐新世气候转为干旱。δ 18o值呈现负移，与全球变冷事件密切相关。中新世δ 13c值在-2‰~ -4‰之间变化，δ 18o值呈连续负移。平均δ 18o值由中新世早期的-8.5‰降至中新世晚期的-10.0‰。基于稳定同位素的古高程测定结果表明，柴达木盆地西南部在始新世中晚至渐新世的海拔高度约为1500 m。
We investigate the growth of the northern Tibetan Plateau and associated climate change by applying oxygen and carbon isotopic compositions in Cenozoic strata in the southwestern Qaidam basin. The X-ray diffraction and isotopic studies reveal that the carbonate minerals are mainly authigenic and they do not preserve any evidence for detrital carbonate and diagenesis. The isotope data show large fluctuations in theδ18O andδ13C values in the middle–late Eocene, indicating relatively warm and seasonal dry climate. The positive correlation of theδ18O andδ13C values in the Oligocene and the positive shift of theδ13C values from the Eocene to Oligocene suggest that the climate changed to arid in the Oligocene. However, theδ18O values show negative shift, which is closely related to the global cooling event. During the Miocene, theδ13C values vary between –2‰ and –4‰, whereas theδ18O values show continuous negative shift. The meanδ18O values decrease from –8.5‰ in the early Miocene to –10.0‰ in the late Miocene. The stable isotope-based paleoaltimetry results suggest that the elevation of the southwestern Qaidam basin was approximately 1500 m in the middle–late Eocene and Oligocene. Subsequently, during Miocene the crustal uplift process started and the elevation reached approximately 2000 m in the early Miocene and 2500 m in the late Miocene, which suggests large-scale growth of the northern Tibet Plateau during the Miocene.