太平洋板块形成以来的中国东部构造动力学背景

构造动力学研究是分析区域构造、沉积演化、岩浆活动及矿产分布的重要前提,前人研究证实自太平洋板块形成以来中国东部构造动力学背景发生了多次转变,但对于具体的转换机制还缺乏深入研究.为此,首先基于对近年来发表的同位素年龄和古地磁数据的系统收集和整理,对太平洋板块形成以来围限中国东部的太平洋板块、印度板块和菲律宾海板块等的形成年代、漂移轨迹和速率变化规律进行了详细梳理.然后依据这3大板块及其周缘板块的运动学规律,结合区域上的构造变形特征,将太平洋板块形成以来的中国东部构造动力学背景划分为:中侏罗世—早白垩世((175 ～ 170) ～ (145±5),(145±5) ～ 125和125～95 Ma BP)、晚白垩世—古近纪(95 ～ 80,80 ～ 43和43 ～ 23 Ma BP)和新近纪—第四纪(23 ～ 10 Ma BP和10 Ma BP至今)等多个阶段.指出中国东部中侏罗世—早白垩世为压扭性背景,晚白垩世—古近纪则转为伸展拉张背景,到了新近纪—第四纪又转变为挤压背景,并对这3大阶段不同时期构造动力学背景作了进一步的论述.

Tectonic Dynamics of Eastern China Since the Formation of the Pacific Plate

Tectonic dynamics is very important to the analysis of regional tectono-sedimentary evolution, volcanic magmatic action and metallogenic regularity. Although a lot of researchhave proved that the tectonic dynamics had changed many times since the development of the Pacific plate, the varied mechanics needs to be explored deeply. In this paper, based on the collecting and sorting of the isotopic age and paleomagnetic data published recently, the drift trajectories and velocities of the Pacific plate, India plate and Philippines Sea plate since its distributions near the eastern China, are analyzed firstly. And then, according to the kinematics characteristics of these three main plates, as well as the regional tectonic deformation features, since the formation of the Pacific plate, the tectonics dynamics background of eastern China can be divided into three stages: The Middle Jurassic Early Cretaceous ((175~170)~(145±5) Ma, (145±5)~125 Ma and (125~95) Ma BP), the late Cretaceous-Paleogene (95~80 Ma, 80~43 Ma and 43~23 Ma BP) and the Neogene-Quaternary 23~10 Ma BP and 10 Ma BP to present). It is pointed out in the paper that the tectonic dynamics mechanics of eastern China in the Middle Jurassic-Early Cretaceous are compress shearing, changed to stretching and extension in the late Cretaceous Paleogene, and then turned to compression in the Neogene-Quaternary is point out, and the specific changes in these three tectonic dynamic stages are discussed in detail at last.