中国毗邻海域构造聚煤带

TECTONIC COAL-FORMING BELT IN CHINA ADJACENT SEA AREAS

中国毗邻海域不仅有丰富的石油和天然气的赋存,还有发育良好的含煤建造和煤层的存在.具有含煤建造形成和发育时间长、分布广,厚度大、沉积类型多、煤层层数多等特征,煤的变质程度是有规律变化,油气与煤层共生.作者认为,在海区进一步研究它和油气的综合开发利用,探讨两者的成因联系,具有重要的经济和理论意义.

China adjacent sea (Bohai Sea, Huanghai Sea, East China Sea and South China Sea) areas are proved by exploration to have not only rich oil and gas resources, but also well-developed coal formation and coal beds. The coal-for-ming belts can be divided into the Bohai Sea, the southern Huanghai Sea, the East China Sea continantal shelf, and the north part of the South China Sea coal regions. The coal formation shows a wide time-space distribution in the sea areas, with the following seven characteristics: (1) coal convergence goes through whol Cenozoic time; (2) coal formation is widespread and also very thick. For example, the thickness is above 3000m in the East China Sea con-tinental sbelf and in the Zhujiang River mouth of the South China Sea; (3) there are many sedimentation types in coal formation and many sedimentary invironments, such as fluvial facies, lake facies, swamp facies, delta facies, sea-land transition facies, and shallow sea facies; (4) coal is multibedded and concentrated, generally with 20 layers or so. There are nearly 100 layers in the East China Sea continental shelf; (5) coal metamorphism changes regularly, mainly represented by brown coal at low metamorphism in China Sea areas, however, metamorphism tends to increase gradually, from shallow to deep coal beds, and even coke coal can be seen; (6) coal is associated with oil and gas, showing a superposition structure. There is oil and gas in coal-bearing segme-nts. Gas occurs in the coal bed or covers coal-bearing segments. It indicates that they have close origin relations; and (7) there are many stages of coal convergence, Coal formation was built up during initial-motion and intense-motion stages of tectonic activities. On the whole, Cenozoic sedimentation in China sea areas undergoes land, land-sea transition and sea environments. Due to different geotectonic locations and different history developments of the Bohai Sea, Huanghai Sea, East China Sea and South China Sea, they have different sedimentary features. These seas are diwa regions formed at different bases in tectonic activities. Their developments have experienced initial-motion ,intense-motion and residual-motion stages respectively.