论热水沉积岩相及其构造古地理

Hydrothermal sedimentary lithofacies and their tectono-palaeogeography

热水沉积岩相形成于裂谷盆地、洋中脊(有限洋盆)、弧—盆系统、陆缘盆地、陆内湖相盆地等不同的构造古地理单元内。按照成岩成矿方式—岩石组合—地球化学动力学分类原则,热水沉积岩相类型可划分为热水同生沉积岩相、热水准同生交代岩相、热水同生蚀变岩相、热水爆炸—液压致裂角砾岩相、热卤水准同生渗滤交代岩相与热流柱构造有关的热流体隐爆—液压致裂角砾岩相,包括不同成岩方式形成的17种构造岩相学类型,它们是建立构造岩相学独立填图单元的基础。热水流体系统的根部相→喷口相→中心相→过渡相→远端相,具有显著的构造岩相学分带和相体分布规律,但在现今陆内造山带中,它们多经历了碎裂岩相、糜棱岩相和热流体改造—叠加—再造成岩相,需进行构造岩相学变形史研究和构造岩相学变形筛分,才能有效恢复它们形成时的构造古地理,促进提升对深部隐伏构造岩相学探测与资源预测的准确性。

Hydrothermal sedimentary facies can be formed in rifted basins,mid-oceanic ridges,arc-basin system,as well as epeiric basins and intracontinental lacustrine basins.According to diagenetic and metallogenic modes,rock associations,and geochemical dynamic classifications,hydrothermal sedimentary lithofacies may be classified into hydrothermal syngenetic sedimentary lithofacies,hydrothermal quasi-syngenetic metasomatism lithofacies,hydrothermal syngenetic altered lithofacies,lithofacies of hydrothermal-blasting to hydraulic fracturing breccias,lithofacies of thermal brine quasi-syngenetic infiltration-metasomatism,and lithofacies of crytoexplosive to hydraulic fracturing breccias by hydrothermal fluids related to hydrothermal plume,including 17 types of tectonic lithofacies.All of them are of basic to establishment of independent tectonic mapping elements.The root,vent,center,proximate,and distal facies of the hrdrothermal fluid system have obvious tectonic lithofacies zonation and distribution in basins.However,all of them experienced deformations such as cataclastic rock facies,mylonite facies,and facies of the altered rocks related to thermal fluid reworking,overprinting,and reconstruction in intrcontinental orogens.After studies on deformation history and deformation-sieving of tectonic lithofacies,their tectono-palaeogeography units can be better understood.It may further help us to improve detecting buried tectonic lithofacies and mineral resource predication.