华南晚元古代—三叠纪构造事件与应力场

本文研究了华南3个板块（扬子、南华与湘桂）和保山、临沧地体自晚元古代到三叠纪的5次重要构造事件的沉积古地理与形变特征、主应力方向以及相关的变质与岩浆活动特征。晋宁事件,华南各板块已联成一体,当时在南北向挤压作用的影响下,造成一系列轴向东西的同斜褶皱。元古代末期一古生代早期发生明显的张裂,使各板块分离。早古生代晚期（晚加里东事件）,南华与湘桂板块发生褶皱,前者受到近东西向的挤压,后者则受到近南北向挤压,它们当时与扬子板块有相当的距离,杨子板块与中朝板块内未发生褶皱变形。海西事件以扬子板块边部的明显张裂作用为特征。印支事件早期（早三叠世）。保山地体向东俯冲,与扬子板块拼合,尔后,在中三叠世末期,使南华、湘桂板块向北位移与扬子板块拼合,在晚三叠世末期,中朝板块才与扬子板块拼合起来,形成大别山两侧的逆掩断裂系与淮阳弧形构造系。印支事件使华南各板块重新拼合,为该区构造格架基本定型的时期。

TECTONIC EVENT AND STRESS FIELD OF LATE PROTEROZOIC-TRIASSIC IN SOUTH CHINA

The rock deformation, principal stress orientation, sedimentation, metamorphism and magmatism of five important tectonic events since late Proterozoic to Triassic for the three plates ( Yangzi, South China and Xianggui ) and Lincang, Baoshan terranes of South China are discussed. In the Jinning stage, the plates of South China were linked up as a whole continental crust, a series of isoclinal folds with an east-westward oriented axis were formed by north-southward compression. Since the Sinian to Ordovician period ( the early Caledonian event) the plates were subjected obviously to extension. During the late stage of early Paleozoic (the late Caledonian event) the South China and Xianggui plates were folded, the former underwent a near east-westward compression and the latter an almost north-southward one, they were separated by a considerable distance to the Yangzi plate, while in the Yangzi and China-Korea plates, the Caledonian folding event were not developed. The Hercynian event is characterized by the distinct extension occurred on the boundaries of Yangzi plate. During the early Triassic ( early Indosinian event ), the Lincang, Baoshan terranes subducted to the east and coalesced with the Yangzi plate. In the late stage of middle Triassic ( middle Indosinian event ), South China and Xianggui plates drifted to the north and coalesced with the Yangzi plate. After that, during the end of late Triassic (late Indosinian event), the Yangzi plate migrated to the north and collided with China-Korea plated. The thrust systems on the both sides of Dabieshan and the Huaiyang arc structural system were developed. The plates of South China were recoalesced in the Indosinian stage, and this is the fundamental finalizing stage of tectonic framework in the area.