Zhang Zhen-Jie, Chen Guo-Xiong, Kusky Timothy, Yang Jie, Cheng Qiu-Ming
School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China.
State Key Lab of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China.
Sci Adv. 2023 Dec 15;9(50):eadi2134. doi: 10.1126/sciadv.adi2134.
The lithosphere, as the outermost solid layer of our planet, preserves a progressively more fragmentary record of geological events and processes from Earth's history the further back in time one looks. Thus, the evolution of lithospheric thickness and its cascading impacts in Earth's tectonic system are presently unknown. Here, we track the lithospheric thickness history using machine learning based on global lithogeochemical data of basalt. Our results demonstrate that four marked lithospheric thinning events occurred during the Paleoarchean, early Paleoproterozoic, Neoproterozoic, and Phanerozoic with intermediate thickening scenarios. These events respectively correspond to supercontinent/supercraton breakup and assembly periods. Causality investigation further indicates that crustal metamorphic and deformation styles are the feedback of lithospheric thickness. Cross-correlation between lithospheric thickness and metamorphic thermal gradients records the transition from intraoceanic subduction systems to continental margin and intraoceanic in the Paleoarchean and Mesoarchean and a progressive emergence of large thick continents that allow supercontinent growth, which promoted assembly of the first supercontinent during the Neoarchean.
岩石圈作为地球最外层的固体圈层，保存着地球历史上地质事件和过程的记录，且时间越久远，记录越零碎。因此，岩石圈厚度的演化及其对地球构造系统的连锁影响目前尚不清楚。在此，我们基于全球玄武岩岩石地球化学数据，利用机器学习追踪岩石圈厚度历史。我们的结果表明，在古太古代、古元古代早期、新元古代和显生宙期间发生了四次显著的岩石圈变薄事件，期间伴有岩石圈增厚的情况。这些事件分别对应超级大陆/超级克拉通的裂解和聚合时期。因果关系研究进一步表明，地壳变质和变形样式是岩石圈厚度的反馈。岩石圈厚度与变质热梯度之间的互相关记录了从古太古代和中太古代洋内俯冲系统到大陆边缘和洋内的转变，以及大型厚大陆的逐渐出现，这使得超级大陆得以生长，从而促进了新太古代第一个超级大陆的聚合。
