黔桂地区海西—印支阶段的构造古地理演化及沉积盆地的时空组合

THE TECTONO-PALAEOGEOGRAPHIC EVOLUTION AND TIME-SPACE ASSOCIATION OF SEDIMENTARY BASINS OF GUIZHOU AND GUANGXI PROVINCES IN HERCYNIAN-INDOSINIAN STAGE

本文在详细研究各类沉积盆地的成因地层格架和鉴别古构造运动面性质的基础上,将黔桂地区的海西—印支构造阶段进而划分为3个构造古地理演化阶段:早海西(D—C_1)的前陆盆地演化阶段;中海西(C_2—P_1)的扬子陆块扩大和稳定沉降阶段;晚海西—早印支(P_2—T_2)的次生深海盆地形成和扩张阶段,从晚二叠世的半地堑式裂陷盆地系和基性火山活动的出现,到早、中三叠世次生深海盆地的发育,说明经历了长期镶嵌过程的扬子陆块再次被解体和开裂。

On the basis of research on genetic stratigraphic framework of different sedimentary basins and recognition of the properties of palaeotectonic unconformity surface,Hercynian-Indosinian tectonic stage may be subdivided into three tectono-palaeogeographic developing stages: early Hercynian stage(D-C1) when the foreland basin developed, medium Hercynian stage (C2-P1 ) when Yangtze continental plate expanded and was subsiding slowly, late Hercynian-early Indosinian stage ( P2-T2 ) when the secondary oceanic basin formed and was spreading. This developing history from the occurrence of rifting semigraben system and basic volcanic activities during Late Permian to the development of the secondary oceanic basin during Early-Medium Triassic shows that the Yangtze continental plate, which has been inlaid for long period, might split and open again.