CAJ | 학술논문

油砂山断裂是柴西主干断裂之一。多年来，对英北断裂的活动时限和形成机制众说不一，有人认为是Ⅺ号断裂的上分支，形成时间早，新生代以来持续活动；也有人认为是油砂山断裂在喜马拉雅运动中的派生断裂，与油砂山断裂同期形成，时间为上新世下油砂山组沉积时期。借助野外露头调查和断裂样品的ESR年龄测试结果，结合三维地震资料，从生长地层发育情况、断裂生长指数分析和主应力方向变化与构造形变关系等角度对英北断裂的活动时限和形成机制进行了约束与探讨，指出：（1）英北断裂是喜马拉雅晚期油砂山断裂右行压扭走滑过程中派生出来的P断裂，与Ⅺ号断裂无关；（2）其形成时间晚于油砂山断裂，活动时限为中更新世，距今约50万年；（3）英北断裂不参与该地区早期油气的运聚，但对晚期的油气调整具有一定作用。
유사산단렬시시서주간단렬지일。다년래，대영북단렬적활동시한화형성궤제음설불일，유인인위시Ⅺ호단렬적상분지，형성시간조，신생대이래지속활동；야유인인위시유사산단렬재희마랍아운동중적파생단렬，여유사산단렬동기형성，시간위상신세하유사산조침적시기。차조야외로두조사화단렬양품적ESR년령측시결과，결합삼유지진자료，종생장지층발육정황、단렬생장지수분석화주응력방향변화여구조형변관계등각도대영북단렬적활동시한화형성궤제진행료약속여탐토，지출：（1）영북단렬시희마랍아만기유사산단렬우행압뉴주활과정중파생출래적P단렬，여Ⅺ호단렬무관；（2）기형성시간만우유사산단렬，활동시한위중경신세，거금약50만년；（3）영북단렬불삼여해지구조기유기적운취，단대만기적유기조정구유일정작용。
The Youshashan fault,whose lower side is Ⅺ fault with south-dip and upper side is Yingbei fault paralleling to Ⅺfault,is one of the major faults in western Qaidam Basin.In recent years,there were different views on activity period and formation mechanism of Yingbei fault.Some researchers thought that it was the up-per branch of Ⅺ fault with early formation period and ongoing activity since Cenozoic.And some of them thought that it was a derived fault with the same period in the formation of Youshashan fault in Himalayan Move-ment,and the exact time is during the deposition of Youshashan Formation in Pliocene.In this paper,accord-ing to outcrop survey,ESR dating data and 3D seismic data,we did some discussion on activity period and formation mechanism on the base of growth strata development,fault growth index analysis and the relationship between principal stress directions change and tectonic deformation.And then we conclude that:(1 )Yingbei fault was a P fault generated from right lateral torsion slip activity by Youshashan fault in late Himalayan Move-ment,and it has nothing to do with Ⅺ fault;(2)Its formation period is mostly the Middle Pleistocene,about 500,000 years ago,later than that of Youshashan fault;(3)Yingbei fault is not involved in early oil and gas migration and accumulation,but it plays a certain role in late oil and gas adjustment.