变形和板块构造的演变
Robert M Holder1,2, Daniel R Viete3, Michael Brown4
1Morton K. Blaustein Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA. roholder@umich.edu.
Nature
|August 9, 2019
概括
自新古时代以来,板块构造与地球的冷却地幔逐渐演变. 对变态岩石的分析揭示了双模热梯度的逐渐出现,表明向现代构造过程的缓慢过渡.
科学领域:
- 地球科学
- 地质学
- 构造学
背景情况:
- 地球的地幔对流驱动板块构造和行星的热量损失.
- 板块构造的时间和演变是地球科学中基本的,但具有挑战性的问题.
- 变态岩石记录了压力-温度 (P-T) 条件,反映了构造环境.
研究的目的:
- 调查地球构造过程的长期演变.
- 确定板块构造何时以及如何在地质时间内出现和发展.
- 使用变态P-T数据作为构造机制变化的代理.
主要方法:
- 随着时间的推移而变形的P-T分布的统计评估.
- 在岩石中分析明显的热梯度 (变态T/P).
- 现代双模变形图案与古代岩石记录的比较.
主要成果:
- 地球的现代板块构造制度自新古时代 (25亿年前) 开始逐渐发展.
- 变态的P-T分布显示了从新古时代到现在的渐进式扩大和增加的双模式.
- 自古原生态时代以来,平均变态T/P已经下降.
结论:
- 板块构造学并没有突然过渡,而是随着地幔的冷却逐渐演变.
- 双模变形的出现意味着现代构造过程的缓慢发展.
- 这与先前的突如其来的构造风格变化或现代板块构造的早期开始的假设形成鲜明对比.
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