Ning Wenbin, Kusky Timothy, Wang Lu, Huang Bo
State Key Laboratory of Geological Processes and Mineral Resources, Center for Global Tectonics, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China.
Badong National Observation and Research Station of Geohazards, Three Gorges Research Center for Geo-Hazards, China University of Geosciences, Wuhan 430074, China.
Proc Natl Acad Sci U S A. 2022 Apr 12;119(15):e2117529119. doi: 10.1073/pnas.2117529119. Epub 2022 Apr 4.
SignificanceThe onset time of plate tectonics is highly debated in the Earth sciences. A key indicator of modern-style plate tectonics, with deep subduction of oceanic plates, is the presence of eclogite (oceanic crust metamorphosed at high-pressure and low-temperature) in orogenic belts. Since no orogenic eclogites older than 2.1 billion y are currently documented, many scientists argue that modern plate tectonics started only 2.1 billion y ago (Ga). We document an Archean orogenic eclogite, providing robust evidence that subduction of oceanic crust reached to at least 65 to 70 km in depth at circa 2.5 Ga. This extends the known age of subduction-related eclogite-facies metamorphism back 400 My, showing that modern-style plate tectonics operated by the close of the Archean.
意义
板块构造的起始时间在地球科学领域备受争议。现代板块构造的一个关键指标是大洋板块的深度俯冲，其标志是造山带中存在榴辉岩（在高压和低温条件下变质的洋壳）。由于目前尚无记录显示年龄超过21亿年的造山榴辉岩，许多科学家认为现代板块构造始于21亿年前（Ga）。我们记录了一块太古代造山榴辉岩，有力地证明了在约25亿年前洋壳俯冲深度至少达到了65至70千米。这将与俯冲相关的榴辉岩相变质作用的已知年龄向前推了4亿年，表明现代板块构造在太古代末期就已存在。
