东海丽水椒江新生代凹陷基底的岩性及分布

根据区域二维地震剖面和钻孔资料,研究东海丽水-椒江新生代凹陷基底的岩性及其分布,发现基底岩性有变质岩、花岗岩、火山岩、沉积岩及火山岩-沉积岩互层.其中,变质岩基底的地震反射多为连续性差、视频率低、中等—弱振幅,主要分布在丽水西次凹和椒江凹陷周围;花岗岩基底多为丘状外形、内部杂乱的弱反射,火山岩基底为连续性中等—较好、视频率低的层状强反射,两者主要分布在丽水-椒江凹陷的东北部;沉积岩基底为连续性中等—较好的中—高频反射,主要分散在丽水凹陷;火山岩-沉积岩互层基底主要分布在丽水-椒江凹陷的中心区域,其对应地震反射的连续性、振幅及视频率等在空间上变化较大.

Basement Lithology and Distribution of Lishui Jiaojiang Cenozoic Sag in East China Sea

The lithology and distribution characteristics of the basement in Lishui Jiaojiang Cenozoic Sag were studied according to 2D seismic profiles and borehole data. As a result, metamorphic, granite, volcanic, sedimentary and volcanic sedimentary interbedded rocks basement units were qualitatively differentiated. The metamorphic rocks basement generally surrounds the central parts of the West Lishui Sub sag and Jiaojiang Sag with discontinuous, low frequency and moderate to weak amplitude seismic reflectors. However, in the northeast regions of the Lishui and Jiaojiang sags dominantly site the granite and volcanic rocks basement, in which the former appears to be mounded geometries with chaotic and weak amplitude internal reflections, whereas the latter represents a good stratification with moderate to continuous, low frequency and strong amplitude reflectors. Besides, the sedimentary rocks basement scattersl mainly in the Lishui Sag with moderate to continuous and strong amplitude reflectors, whereas the volcanic sedimentary interbedded rocks basement largely covers the central area of the Lishui Jiaojiang Sag with the continuity, frequency and amplitude varying violently in spatial.