东海西湖凹陷构造演化及控煤作用

Tectonic evolution and control of coal in Donghai Xihu sag

西湖凹陷是经历了多期构造作用的新生代弧后盆地。在对其区域构造和其内部构造特征分析的基础上,利用平衡剖面技术,探讨西湖凹陷构造演化特征及控煤作用。研究结果表明:西湖凹陷具有"东西分带、南北分块"的构造格局;受区域演化的影响,西湖凹陷构造演化可分为断陷期、坳陷期和区域沉降期;聚煤前的平坦地形、聚煤期的同沉积构造坡折带的发育及聚煤期后一系列反转构造,造就了西湖凹陷现今煤层气赋存特征。

Xihu sag is a Cenozoic back-arc basin which experienced multi-episodic tectonic setting. Based on theanalysis of characteristics of regional structure and its internal structure, on the basis of using balanced sectiontechnique, the tectonic evolution characteristics of Xihu sag and control of coal were discussed. The results showedthat Xihu sag has the structure of “Zonation in latitudinal direction and blocking in longitudinal direction” pattern.Under the control of the regional evolution, Xihu sag tectonic evolution can be divided into fault depression stage,depression stage and regional subsidence stage. Coal accumulating effect before the flat terrain, coal accumulatingperiod of development of syndepositional structural slope-break zone and coal accumulating a series of inversionstructures, which formed the current CBM regularity of Xihu sag.