右江沉积盆地的性质及演化讨论
NATURE AND EVOLUTION OF THE YOUJIANG BASIN
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摘要: 右江盆地是指海西—印支期由师宗—弥勒断裂、红河断裂、紫云—南丹—河池断裂和灵山断裂所围限的滇黔桂地区。长期以来,由于该盆地所处的特殊构造背景、独特的岩相-构造格局和丰富的矿产资源,许多地质工作者都予以充分注意,对该盆地的性质提出了众多有益的观点和认识,除传统的槽、台、洼学说外,先后有“弧间盆地或弧后盆地”、“湘桂边缘海”、“弧后裂谷地槽”、“右江裂谷带”和“裂陷槽”等等。笔者参考了这些前人的工作成果,并据自己的研究,参与这一讨论,亦望同行指正。Abstract: The study of sedimentation, tectonism and magmatism shows that the Hercynian-Indosinian Youjiang Basin may be ascribed to a passive rift basin which was controlled during its formation and evolution by the opening and closing of the palaeo-Tethys. The basin consists of several regional fault-related secondary NW-and NE-trending basins in which lithofacies and tectonic framework are quite variable in character. The NW-trending basins were formed largely by extensional faulting, whereas the NE-trending ones have the characteristics of the strike-slip basins. The following five stages have been distinguished for the evolution of the Youjiang Basin:(1) intracontinental rifting stage; (2) passive marginal rifting stage; (3) back-arc rifting stage; (4) strongly subsiding stage, and (5) filling-closing stage.