东海西湖凹陷平湖斜坡带断层特征及其封闭性

在对西湖凹陷平湖斜坡带断裂系统特征定性分析的基础上,结合断层封闭性的半定量研究,总结了平湖斜坡带断层的封闭性特征。依据主干断裂及伴生断裂的平面组合样式、剖面组合关系等特征,将平湖斜坡带断裂系统划分为4个断裂带,由北至南依次为"K"同向断裂带、"W"反向断裂带、"P"同向断裂带和"N"堑式断裂带。断层封闭性研究认为平湖斜坡带中部断层封闭性要好于南部和北部。"K"同向断裂带和"W"反向断裂带多数断层封闭性较好,但由于平湖主断裂的长时间活动,使得整体封闭性一般。"P"同向断裂带由于受中新世末龙井运动的弱挤压反转作用,断层的封闭性较好。"N"堑式断裂带由于平湖主断裂的长期活动和沉降期断裂的存在,断层封闭性较差。

CHARACTERISTICS OF FAULTS ON THE PINGHU SLOPE OF XIHU SAG, THE EAST CHINA SEA SHELF BASIN AND THEIR SEALING CAPACITY

Based on the qualitative analysis of the faults on the Pinghu slope of Xihu Sag, we conducted the semi-quantitative study of their sealing capacity in this paper. According to the lateral and vertical framework of the faults, the fault system in the Pinghu slope can be divided into four fault zones, i. e. the "K" synthetic fault zone, "W" antithetic fault zone, "P" synthetic fault zone and "N" graben-type fault zone from north to south. Results showed that the fault sealing capacity was higher in the middle part of the slope rather than in the south and north parts. The sealing capacity of most "K" synthetic fault zone and "W" antithetic fault zone was high. However, due to the long-term activity of the main Pinghu fault, the fault sealing capacity became ordinary as a whole. As the result of the weak compressive inversion of the Longjing movement by the end of Miocene, the sealing capacity of the "P" synthetic fault zone was fine. But the fault sealing capacity of the "N" graben-type fault zone was low, due to the long-term activity of the main Pinghu fault and the occurrence of the faults in subsidence period.