Response of Magnetic Fabric of Xichagou Section in Late Tertiary to Climate Change,Western Qaidam Basin
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摘要: 通过对柴达木盆地西部(简称柴西地区)的干柴沟背斜南西翼的西岔沟层型剖面进行系统测制和2～3 m等间隔磁性地层学、磁化率各向异性系统采样，并进行精确测量，利用在该区建立的高分辨率、高精度磁性地层年代资料，结合沉积学等研究，讨论了磁化率各向异性参数变化趋势对环境的指示，并揭示在约23～6.2 Ma期间环境演化经历了三个阶段：Ⅰ阶段(22.4～13.4 Ma)为湿润环境；Ⅱ阶段(13.4～8.2 Ma)为温干环境向干冷转型；Ⅲ阶段(8.2～6.2 Ma)气候转冷变干且变化更复杂。认为7.8 Ma以来气候转型及有规律的变化与现代季风形成有关。为青藏高原的隆升过程及其环境效应提供可靠资料。Abstract: Through equidistantly sampling on 2～3 meters and accurate systematic measurement of samples of Xichagou stratotype section, located in southwesern limb of Ganchaigou anticline in western Qaidam Basin(Chaixi area) ,integrated high resolution and high precision magnetostratigraphy and sedimentological study in this section, authors think the changing trends of magnetic fabric parameters of sedimentary rocks may act as proxies of climate change.It was indicated that environmental change between 22.4 to 6.2 Ma may divide into three stages: first stage: humid context between ~22.4 to 13.4 Ma; secondary stage: warmarid environment transformed aridcold one from 13.4 to 8.2 Ma, and third stage from 8.2 to 6.2 Ma, climate lasted drycold, and more complexly. It can be considered that rhythm of climate change or tectonism correlated to formation of modern monsoon since 7.8 Ma. This result provides available evidence for the uplift process of Tibetan Plateau and its environmental effectes.
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Key words:
- magnetic fabric /
- Qaidam Basin /
- climate change /
- Xichagou
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