PRIMARY RESEARCH OF ACTIVITY SEGMENTATION OF LONGMENSHAN FAULT ZONE SINCE LATE-QUATERNARY
PRIMARY RESEARCH OF ACTIVITY SEGMENTATION OF LONGMENSHAN FAULT ZONE SINCE LATE-QUATERNARY
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发表时间：
2007
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通讯作者：
Chen Guo-guang
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作者：
Chen Guo-guang
龙门山断裂带位于松潘-甘孜造山带与扬子地块之间，呈NE向，由后山断裂等4条主要断裂及相关逆冲岩片组成，是一个以前展为特征的推覆构造，形成于印支运动时期，此后多次活动，第四纪以来活动频繁，本文根据地貌、地质、布格重力异常和地震资料，对该断裂带进行了综合分析，结果表明，位于沿着北川-安县的近南北走向的雷东断裂，是龙门山断裂带中段与东北段的分界线，两段活动性差异较大，中段晚更新世以来活动频繁，中小地震频繁，东北段第四纪以来活动微弱，偶有小震发生，由于青藏高原的挤压隆升和侧向滑动，其中，川青块体向东南向运动，形成了块体活动边界，该边界包括名山隆起和龙门山断裂带中段、西南段，二者均被名山隆起截断，龙门山断裂带东北段已废弃。
The Longmenshan Fault zone,trending in NE,lies between the Songpan-Ganzi orogenic belt and the Yangzi block.It consists of four major faults,such as the Houshan Fault,and related thrusting sheets.It is a nappe structure characterized by forward spreading.It formed during the Indo-China movement and was active many times since then.Since the Quaternary,this fault zone has been very active,and exhibits differential activity on its various sections.In this work,we make an integrated analysis of this fault zone based on data of geomorphology,geology,Bouguer gravity anomalies,and earthquakes.The results show that the near NS-striking Leidong Fault,located along Beichuan-Anxian,is the boundary between the middle and northeastern sections of the Longmenshan Fault zone.The two sections have high distinctive activity.The middle section is very active since late Pleistocene time with frequent medium-and small-sized earthquakes,while the northeastern section has weak activity since Quaternary with occasional small earthquakes.Due to the compression and uplift of the Tibetan Plateau and lateral sliding of blocks,the Sichuan-Qinghai block moves towards SEE,resulting in an active boundary of the block.This boundary includes the Mingshan uplift and the middle and southwestern sections of the Longmenshan Fault zone,both of which are truncated by the Mingshan uplift.And the northeastern section of the Longmenshan Fault zone has been abandoned.