Early to mid-Pleistocene ostracod δ

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• 作者：Zhangdong Jin ; Mike J. Bickle ; Hazel J. Chapman ; Jimin Yu ; Sumin Wang ; Shiyue Chen
• 关键词：Indian monsoon ; Ostracod shell ; Stable isotopes ; Lake sediment ; Central Tibetan Plateau
• 刊名：Palaeogeography, Palaeoclimatology, Palaeoecology
• 出版年：2009
• 出版时间：15 September 2009
• 年：2009
• 卷：280
• 期：3-4
• 页码：406-414
• 全文大小：1102 K

文摘

As one of the pioneering projects of the Chinese Environmental Scientific Drilling (CESD) Program, a 206.5 m long sediment core (CE) was retrieved from Co Ngoin (Co = lake) Basin in the central Tibetan Plateau. Limnic records of the abundance of ostracod shells and their oxygen and carbon isotope measurements, together with the geochemical and the sedimentological investigations, were carried out on the interval between 143 and 52 m core depths, corresponding to ca. 2.01–0.84 Myr. Distinct oscillations of the abundance and the chemical compositions of ostracod shells have yielded the original information about variations in lakewater chemistry in association with the change in the Indian monsoon over the period of 2.01 to 0.84 Myr. The climate conditions during the Early Pleistocene were characterized by frequent oscillations and the ostracod records had expressed its synchronous response to these oscillations. A major climate change occurred in the Co Ngoin area at about 0.93 Myr. A pronounced fluctuation in ostracod δ¹⁸O and δ¹³C during the Mid-Pleistocene transition (MPT) is possibly associated with an increase in continental ice sheets. The compositional and the sedimentological characters of the immediately overlying sediments imply a shallow aquatic environment and also a harsh (salinity?) condition beyond the tolerance limits for ostracod survival, resulting in the disappearance of the Qinghaicypris crassa Huang 1979 around 0.84 Myr.