微板块与大板块:基本原理与范式转换

Microplate and megaplate:fundamental principles and paradigm transition

传统板块构造理论50多年来一直是占统治地位的地学理论,是理解固体地球运行的基本范式,但遇到三大难题:板块起源、板内变形和板块驱动力。针对这三大难题,微板块构造理论试图开拓一个全球构造研究的新范式。本文通过与传统板块构造理论中基本原理的逐条对比,阐明了微板块构造理论的基本原理和优势及其对传统板块构造理论的拓展。微板块构造范式既不同于传统板块构造范式,又不同于地幔柱范式,是两者的重要补充与拓展。文中着重从几何学、运动学、动力学、适用范围、理论出发点、理论假设与预测的角度,阐明了大板块与微板块的异同,并探讨了两者的转换关系及其转换机制的多样性,介绍了微板块生长成为大板块的4种途径、大板块破碎为微板块的3种转换模式,探索了前板块构造体制下微地块在非线性地球系统中通过自组织、自生长等方式,进化为板块体制下微板块的自然选择过程。本文还提出陆壳型微地块是密度选择的结果,其密度决定了其保存机制,这是陆壳起源的根本;微地块向微板块的转变是刚性选择的结果,其刚性是初始板块构造体制起始的必要条件;微板块不对称俯冲或对流型式的转变是热选择的结果,其热不对称性是现代板块构造体制起始的必要条件。

The traditional plate tectonics theory has been the dominant theory in geoscience for more than 50 years.It is the basic paradigm to understand how the solid Earth operated,but it has encountered three major problems:origin of plate tectonics,intraplate deformation and plate-driving mechanisms.Aiming at these three problems,the theory of Microplate Tectonics attempts to develop a new research paradigm for global tectonics.By comparing with the point-to-point basic principles of the traditional plate tectonic theory,this paper describes the basic principles and advantages of the microplate tectonic theory and its extension to the traditional plate tectonic theory.Microplate tectonic paradigm,different from both the paradigm of traditional plate tectonics and mantle plume,is their important supplement and extension.From the views of geometry,kinematics,dynamics,scope of application,theoretical starting point,theoretical hypothesis and prediction,this paper explores the similarities and differences between megaplates and microplates,revealing their transitional relationships and the diversity of transitional mechanism,introducing four growth ways from microplates to large-scale plates and three transition models from large-scale plates to microplates,and exploring the natural selection process of micro-blocks under the pre-plate tectonic system to evolve into microplates under the plate system through self-organization and self-growth in a nonlinear Earth system.It is proposed that the continental crust-type micro-block is a result of density selection,and the density determines its preservation mechanism,which is the basis of the origin of continental crust.The transition from micro-block to microplate is a result of rigidity selection,which determines the necessary conditions for the initiation of the original plate tectonic system.The transition of asymmetric subduction or mantle convection pattern is the result of thermal selection for microplate,and its thermal asymmetry determines the necessary conditions for the initiation of modern plate tectonic system.