克拉通、下地壳与大陆岩石圈——庆贺沈其韩先生百年华诞

Cratonization,lower crust and continental lithosphere

把克拉通、下地壳和大陆岩石圈这几个重要的地质名词放在一起做文章的标题,其实只是想强调一个事情,即陆壳形成和稳定化的结果是形成大陆岩石圈。大陆岩石圈是地球圈层的基本单元,是现代板块构造运动的核心构件和核心载体。忽视大陆岩石圈,要讨论地球上大陆与大洋、地壳与地幔、地球的深部圈层与外部圈层、内部圈层间相互作用以及物质与能量的交换等问题都无法深入。大陆岩石的最初形成可能在冥古宙早期已经开始,全球大陆的稳定化即克拉通化一般认为完成于太古宙末,并开启了元古宙的新纪元。对大陆壳的形成机制和演化过程,已经有很多讨论,但是还存在许多争议。而对大陆岩石圈人们知之不多,文献中常常在早期的小的陆壳形成,即陆核或微陆块阶段,就将其与大陆岩石圈的概念混为一谈。岩石圈的形成固然是大陆形成演化的结果,但是岩石圈的物质组成、结构和物理性质等从最初形成到成熟并成为稳定的地球独立圈层并足以承担板块构造的重任,可能经历了不止一个阶段。本文强调应对岩石圈的形成和演化给予更多的关注,并深化研究大陆地壳形成、克拉通化对大陆岩石圈形成的贡献。

This paper is titled as"Cratonization,lower crust and continental lithosphere"and emphasizes a concept that the formation of the continental lithosphere is a final result of continental growth and stabilization.The initial generation of primitive continental crust is as early as in the Hadean,but the formation of global lithosphere is much later.Continental nucleus or micro-blocks are not equal to lithosphere.Plate tectonics deals with tectonic movements on the lithosphere scale.Cratonization is a key geological process to form stable continental masses with a considerable scale.This causes the continental crust to divide into the stable lower crust and upper crust,and also crust-mantle coupling.The Precambrian global cratonization and formation of supercraton in the world is an unrepeated event in the history of the Earth's formation and evolution.It is possible that the first global lithosphere formed during Neoarchean cratonization.After that,the lithosphere constants adjustment,stability and evolution more than one stage,until the modern situation of the lithosphere became enough to bear the burden of plate tectonics.