桐乡──平湖拗陷大地电磁研究

对桐乡──平湖拗陷大地电磁的研究表明：（１）控制桐乡凹陷和平湖凹陷的南北边界断裂，是火山岩沉积区内的中生代断裂，元古代深断裂实际上是统一的火山岩沉积拗陷的边界断裂。（２）桐乡凹陷和平湖凹陷的基底原来是一个统一的背斜构造，现今所指的平湖凹陷仅相当于桐乡凹陷基底背斜的南翼。推论在其北侧应存在一个对称的沉积凹陷。（３）盖层中的上白垩统兰溪组是一个低阻层，推论该层含有较丰富的泥岩层，可能是有利的生油层。

MT RESEARCH ON THE TONGXIANG AND PINGHU SAGS

The MT researchon the Tong-clang-Pinghu sag indicates that: (1)The northern and southern boundary faults controlling the Tongxiang and Pinghu sags are Mesozoic faults in a volcsnic sedimentary zone. The Proterozoic deep faults are virtually the boundary faults of a unified volcanic sedimentary sags. (2)The basement of the Tongxiang and Pinghu sags was a unified anticline. The Pinghu sag rsfrred here is only the southern wing of the Tongxiang basement anticline in the Tongxiang sag. It is deduced that there may be a symmetrical sedimentary sag on itsnotherm side. (3)The Upper Cretaceous Nanxi Group in the capping bed is a low-resistance formation. It is inferred that there is abundant mudstone in it. It may be beneficial oil-generating strata.