介形类、稳定同位素和风化记录对柴达木盆地中中新世干旱化加剧事件的约束（英文）

作者：宋博文; 季军良; 王朝文; 徐亚东; 张克信

来源：中国古生物学会第十二次全国会员代表大会暨第29届学术年会, 中国河南郑州, 2018-09-17.

• ostracod
• stable isotopes
• Qaidam Basin
• Central Asia aridification

The thick and continuous Cenozoic successions in the Qaidam Basin provide an excellent paleoclimate archive.Here,we focus on the ostracod fauna,stable isotope records,and paleoweathering indices from a welldated Cenozoic sedimentary section in the Qaidam Basin,to develop an understanding of the middle Miocene aridification in central Asia.Microfossil analyses suggest that the ostracod species diversity suddenly decreased after 13.3 Ma,and that the dominant ostracod genus shifted from Ilyocypris to Cyprideis.Stable isotope data from ostracod valves display abrupt positive shifts of 3.75‰ in δ~(18)O values and 5.28‰ in δ~(13)C values since 13.3 Ma.The Chemical Index of Weathering(CIW) and K/Na ratios decrease markedly after 13.3 Ma,reflecting a significant decrease in chemical weathering intensity.These combined and consistent observations suggest that the Qaidam Basin has experienced increased aridification since 13.3 Ma.The dating was obtained direct fromprevious magnetostratigraphic studies and can be accurately correlated with global climate evolution and regional tectonic events.A comparing of these results with global paleoclimatic records and previous geologic studies of the Tibetan Plateau,revealed that global cooling rather than uplift of the Tibetan Plateau played a key role in the drying of the Qaidam Basin at approximately 13 Ma.

• 单位
  生物地质与环境地质国家重点实验室