U-Pb年龄来自中新生态时期的杜尚图形成,中国
Daniel Condon1, Maoyan Zhu, Samuel Bowring
1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. dcondon@mit.edu
Science (New York, N.Y.)
|February 26, 2005
概括
中国的杜尚图岩层在6.35亿至5.51亿年前沉积,与全球降冰相吻合. 它的动物化石大多年龄小于5.8亿年,顶部附近有一次显著的碳同位素游览.
科学领域:
- 地质时间学 (Geochronology)
- 古气候学 古气候学
- 古生物学的古生物学
背景情况:
- 在中国的杜尚图岩层中,有着重要的古生物学和地质记录.
- 它的沉积时间和与马里诺冰川等全球气候事件的关系对于了解早期生命至关重要.
- 之前的研究表明,形成的年龄范围广泛.
研究的目的:
- 通过U-Pb子分析,精确地测定杜尚图形成的日期.
- 与全球气候事件相关联,特别是马里诺冰川结束的Doushantuo形成的沉积时间.
- 为了限制Doushantuo生物群的年龄,并调查相关的碳同位素游览.
主要方法:
- 火山灰床的U-Pb石地质年代学.
- 碳酸盐样本的碳同位素分析.
- 序列战略分析. 序列战略分析.
主要成果:
- U-Pb石的日期将杜尚图形成的沉积置于6.35亿年至5.51亿年前.
- 形成的底部与马里诺冰川的结束同时,表明同步降冰.
- 碳同位素和序列层学数据表明,该形成的动物化石大多年龄小于5.8亿年.
- 一个显著的负碳酸盐碳同位素外流被确定在最上层的杜尚图形成,约为5.51亿年前.
结论:
- 杜尚图形成记录了一个关键时期,涵盖了马里诺冰川的结束和随后的降冰.
- 由于年龄的限制,我们更好地了解了这个群体中早期动物生命的时间.
- 大约5.51亿年前的负碳同位素外流代表了一个潜在的全球事件,影响了早期的生态系统.
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