来自喜马拉雅前陆地盆地的最古老的大陆沉积物的约会
1Fold and Fault Research Project, Department of Geology and Geophysics, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4. y.najman@glg.ed.ac.uk
Nature
|March 10, 2001
概括
新的地球时间学数据显示,喜马拉雅山脉的侵蚀比以前认为的要晚15-20万年. 这一发现需要重新评估印度-欧亚洲碰撞和山脉升起动态的模型.
科学领域:
- 地质地质地质地质地质地
- 构造学 构造学 构造学 构造学
- 地质时间学 (Geochronology)
背景情况:
- 喜马拉雅山脉的发展影响着全球进程,包括高原的升起和气候变化.
- 之前的研究使用巴基斯坦前陆盆地沉积物的生物分层学测定了喜马拉雅侵蚀开始的日期,这表明年龄为55亿年.
- 这个时代对印度-欧亚洲碰撞和山脉形成的模型产生了重大影响.
研究的目的:
- 重新评估最早的喜马拉雅侵蚀时间.
- 重新评估巴基斯坦大陆前陆盆地沉积物的年龄.
- 改进与喜马拉雅山脉土生态相关的构造过程模型.
主要方法:
- 使用40Ar-39Ar地质年代法测定257颗白色银颗粒的年代.
- 详细地质地图的沉积物继承.
- 重新检查了海单位和大陆沉积物之间的分层关系.
主要成果:
- 40Ar-39Ar年代测定给出了36-40 Myr的detrital白的主要年龄集群.
- 这些年龄与以前分配的生物层级图学年龄 (约55亿年) 不一致.
- 结构重新绘制表明,马尔单位是间歇的,使其用于约会整个级继承的使用无效.
结论:
- 带有喜马拉雅碎片的最古老的大陆前陆盆地沉积物至少比以前估计的年龄小15-20万年.
- 这次继承的生物层状图学约会方法由于结构复杂性而不可靠.
- 根据新的年龄限制,对喜马拉雅升起,挖掘和前陆盆地动态的现有模型需要进行重大修订.
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