前寒武纪地球动力学(Ⅵ):华北克拉通形成

Precambrian geodynamics(Ⅵ):Formation of North China Craton

华北克拉通研究近20年来取得一系列重大进展,但是还存很多遗留问题待解决。本文首先探讨了华北克拉通前寒武纪构造单元划分中存在的问题,据此提出了动态构造单元划分原则,并初步动态划分了古—中太古代、新太古代、古元古代、中—新元古代的构造单元,从而确定了不同时期构造格局演变过程。基于新的划分方案和华北克拉通记录的一系列前寒武纪大量重大地质事件,侧重探讨了不同演化阶段的独特构造样式、构造体制机制转变,基于华北克拉通一些太古宙陆核刚性化完成于25亿年,而显著的线性裂谷带或活动带最早出现于22亿年,因此,提出华北克拉通初始板块构造机制起始于新太古代末期的论断,本文约束了区域性垂向构造向区域性水平构造转换的相关构造证据。最后,本文基于长期构造解析的研究,系统论述华北克拉通于18.5亿年的最终集结过程。

The research on the North China Craton has made a series of great progress in recent 20 years,but it still has many un-resolved problems.Firstly,this paper discusses the existing problems in the Precambrian tectonic unit division of the North China Craton,and then proposes some principles of dynamic tectonic unit division,and preliminarily makes dynamic tectonic division of Paleoarchean-Mesoarchean, Neoarchean,Paleoproterozoic and Meso-Neoproterozoic tectonic units,respectively.Based on these tectonic divisions,this paper determines the different periods of unique deformation styles and tectonic evolution.According to the new tectonic divisions and a series of major Precambrian geological events recorded in the North China Craton,different stages of evolution of the unique structural styles and tectonic regimes and their transition are also discussed.This paper proposes the rigid cratonization of some Archean continental nuclei in the North China Craton occurred at about 2.5Ga,however,the obvious and earliest linear tectonic belts or rifts occurred at about 2.2 Ga.Therefore,this paper concludes the judgment of the Neoarchean initiation of plate tectonic regime in the North China Craton and provides the related structural evidences.Finally,based on our longterm structural analysis,this paper discusses the final assembly processes of the North China Craton in 1.85 Ga.