【摘要】 长兴-奉化断裂是斜跨杭州湾地区的一条新生代北西向断裂,改造了该地区印支运动以来北东向为主的构造格局,对区域矿产资源开发、油气勘探有着重要意义。由于该断裂在航磁异常图上表现不明显,地表行迹不连续,且极易与早期断裂的次级断裂混淆,因此该断裂的存在及其几何展布一直有所争议。本文结合杭州湾地区的TM遥感图像解译、布格重力异常场、以及人工地震勘探资料,分析长兴-奉化断裂的几何展布及中新生代活动特征,提出长兴-奉化断裂西起长兴煤山,经桐乡、海宁、余姚、宁波,向东南延伸入海,而非前人据航磁异常提出的自长兴向奉化地区延伸。TM遥感影像解译表明该断裂是由一系列新生的北西向小断裂呈右阶斜列、平行或断续出现所构成,断错了先存的北东向、东西向构造。人工地震资料显示自白垩纪至古近纪,长兴-奉化断裂均有活动,参与控制了杭州湾地区白垩纪-古近纪陆相盆地的沉积。该断裂在地表和剖面上表现为右旋张扭,是中国东部地区北西向断裂系统带的一部分。更多还原

【Abstract】 The Changxing-Fenghua fault (CFF) is a regional fault trending in NW-SE,which diagonally goes across the Hangzhou Bay region.The CFF changed the NE-SW trending tectonic frameworks which were formed in the Indosinian movement.The CFF plays an important role for the development of mineral resources and oil resources.It consists of a series of NW-SE-trending faults which are discontinuous,parallel to each other or dextral en-echelon array.Secondary NW-SE-trending faults of NE-SW-or E-W-trending deep preexisting faults are easily misdeemed from the CFF.Therefore,the distribution,even the determination of the CFF are challenged in recent decades.We analyzed the distribution and activity of the CFF in the Mesozoic and Cenozoic according to the TM remote sensing image,aeromagnetic anomaly map,Bouguer gravitational anomaly map and artificial seismic profiles of the Tongxiang-Pinghu depression,Changhe depression and Ningbo basin.The TM remote sensing image indicates the new NW-SE-trending fractures assemble in Shangyu city,the northern part of Simin Shan and the Ningbo city.And the difference from the previous understanding is that the NW-SE-trending fractures around Fenghua city are only secondary fractures of preexisting deep faults.Although inconspicuous in the aeromagnetic anomaly map and discontinuous on the ground surface,the CFF is a remarkable boundary of positive and negative abnormality on the Bouguer anomaly map.The fracture distribution and the Bouguer anomaly map suggest the CFF starts in Chang-xing County and expends southeastwardly to the East China Sea.The CFF spreads as en-echelon fractures and passes by the Tongxiang,Haining,Yuyao and Ningbo cities,rather than the Fenghua city as people suspected from the aeromagnetic anomaly map before.Artificial seismic exploration showed that the CFF controlled the deposition process and rebuilt the structures of continental basins from the Cretaceous to Eogene.The CFF cut across old structures with dextral horizontal displacement on the ground surface and strata as a normal fault on the artificial seismic profile.Therefore,the CFF is a tenso-shear fault and belongs to the NW-trending active fault zones of the eastern Chinese continent in the Mesozoic and Cenozoic.更多还原