南海天然气水合物的成矿远景

PROSPECT OF GAS HYDRATE RESOURCES IN THE SOUTH CHINA SEA

通过对南海的中新生代区域构造、中上新世沉积、近—现代地貌及地温条件的分析 ,结合 ODP184航次钻探成果和水合物最新调查资料 ,探讨了南海水合物的成矿条件 ,认为具有良好的成矿地质构造环境 ;通过对南海陆坡深水区现有大量多道地震调查资料的重新判读 ,发现南海地区存在多处水合物的地震标志— BSR,以活动边缘笔架增生楔和非活动边缘西沙—东沙为例 ,重点解剖水合物的地震特征 ,建立其成藏模式 ,总结其成矿规律 ,预测水合物资源远景 ,为今后在该海域寻找水合物矿床。

Through the reviewing Miocene regional tectonics,middle Pliocene sediments and recent and modern geomorphic and geothermal conditions in the South China Sea,and together with the latest drilling results and hydrate data from the South China Sea,the authors have made a thorough study on the formation conditions of hydrate in the South China Sea and think that the geologic tectonic environment of the sea is favorable for the formation of hydrate.And after re-interpretation of the available multichannel seismic data from the deep-water areas of the continental slope,double BSR(bottom simulating reflector),slope BSR,platform BSR and basin-edge slope BSR are proven existing in many areas of the sea.Through comprehensive analysis of geophysics,the South China Sea is found to be of BSR,BZ(amplitude blank zone)and VAMP(velocity amplitude anomaly inversion),which are in good coincidence with research results from geologic and geochemical data.An accretion at the active margin and Dongsha-Xisha at the inactive margin are chosen to conduct the studies on hydrate pooling at the margins,probe seismic characteristics of the hydrate,discuss about pooling mechanism,establish the pooling model,summarise mineralization regularities,locate possible occurrence positions of hydrate and predict hydrate prospect. On such basis,the authors give some advance suggestions involving formation environment of hydrate in the South China Sea,dynamic settings and tectonic characteristics,relation between geothermal field features and hydrate formation,hydrate pooling conditions and mechanism,hydrate distributions and resource prospect prediction in the northern continental slope areas,environmental geology and hazard geology of hydrate.These suggestions can play good roles in future explorations for hydrate.