概括
海水中的同位素比率显示出由大陆碰撞影响的长期趋势. 像喜马拉雅山脉的地质变化等重大构造事件,在数百万年的时间里显著改变了这一地质记录.
科学领域:
- 地质化学 地质化学
- 同位素地质学的同位素.
- 构造学 构造学 构造学 构造学
背景情况:
- 海洋水中同位素组成 (87Sr/86Sr) 在地质时间内发生了显著的变化.
- 这种同位素进化在过去的5亿年中表现出不对称的低谷模式.
- 之前的研究已经发现了波动,但缺乏对大规模趋势的全面解释.
研究的目的:
- 调查海水中长期同位素变化的主要驱动因素.
- 为了将主要的地质事件与87Sr/86Sr比率的观察到的变化相关联.
- 了解大陆气候变化和循环对海洋地球化学的影响.
主要方法:
- 从5亿年前的海洋沉积物中分析了同位素数据.
- 斯特循环的地化学建模,包括气候变化动态.
- 同位素趋势与重大构造事件的相关性,特别是大陆碰撞.
主要成果:
- 87Sr/86Sr比率显示出明显的不对称的低谷,高点在坎布里亚和近期,最低点在罗纪.
- 地化学建模表明,大规模的大陆碰撞是影响这种同位素趋势的主要因素.
- 同位素变化的规模表明,只有"喜马拉雅风格"的orogenies才能产生如此重大的转变.
结论:
- 喜马拉雅山脉形成是自泛非洲形成以来影响同位素的最重要的构造事件.
- 大陆碰撞,通过增强的气候和沉积物流动,是控制海水长期87Sr/86Sr演变的主要机制.
- 了解这些联系对于解释地球的地化学历史和构造进化至关重要.
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