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    华南黄陵隆起构造演化及其对页岩气保存的控制作用

    Tectonic evolution of the Huangling uplift and its control effect on shale gas preservation in South China

    • 摘要: 近期中国南方页岩气勘查在黄陵隆起南缘的下寒武统和震旦系取得重大突破,本文针对古老地层页岩气构造保存问题,研究黄陵隆起构造演化历史,反演钻井沉积地层埋藏史,通过二维地震剖面解析黄陵隆起南缘的构造学特征,统计分析相关地质年代学数据。认为该区域在约800 Ma经历了花岗岩侵入,形成了以花岗岩为主体的黄陵隆起基底;该区域在800~200 Ma构造较稳定,缺乏这一时期的构造年代学数据;中侏罗世震旦系陡山沱组埋深可达约8 km,晚侏罗世及以后经过多期抬升至现在的构造格局。本研究说明黄陵隆起的古老基底经过元古宙大量花岗岩侵入,可能均质性高而表现为刚性基底,后期所遭受构造改造程度较低,埋深相对较浅。因此,该地区页岩表现为演化程度适中,构造改造弱,后期热事件影响小,有利于页岩气的保存,是目前黄陵隆起南缘获得页岩气勘查突破的关键。并指出南方具有类似构造的雪峰山隆起、神农架背斜和汉南古陆周缘具有良好的下寒武统页岩气勘查潜力。

       

      Abstract: Significant breakthrough of shale gas exploration has been made in Lower Cambrian and Sinian shale on the north margin of the Yangtze block, South China. In this paper, the authors focused on the preservation condition of shale gas, with the purpose of investigating the tectonic evolution history of the Huangling uplift by means of geological survey and 2D seismic, geochronological and drilling data. The results are as follows:at~800Ma, granite intrusion took place in the Huangling dome basement, primarily shown by granites replacing metamorphism rocks; during 800~200Ma, no significant tectonic movement occurred, with no geochorologic data; the Sinian shale was buried at the depth of about 8km during Middle Jurassic. This study indicates that the rigid basement of the Huangling uplift was mainly composed of homogeneous granite, without intensive deformation. As the main challenges of the widely distributed Lower Cambrians and Sinian shale are high-maturity and intensive deformation, a geological unit with a dome probably is a favorable zone for the old age shale gas. Therefore, it is shown that the adjacent zones of the the Xuefengshan, Shennongjia and Hannan are geological units with a dome and probably have potentials for the exploration of shale in the Lower Cambrian strata.

       

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