雪峰造山带溆浦—靖州断裂活动历史及构造属性

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摘要：溆浦—靖州断裂走向NNE（北段转为NE—近EW向），倾向SE，是雪峰造山带内部一条长期活动的重要断裂。基于与断裂相关的沉积作用、构造变形、岩浆活动等，研究溆浦—靖州断裂的活动历史，进而探讨断裂的构造属性。结果表明：溆浦—靖州断裂自早至晚经历了南华纪伸展、志留纪晚期加里东运动中逆冲、晚古生代伸展、中三叠世晚期印支运动中逆冲、晚三叠世—中侏罗世左行走滑-逆冲、中侏罗世晚期早燕山运动中逆冲、白垩纪伸展、古近纪右行走滑等多期构造活动；溆浦—靖州断裂以西块体相对强硬或不同壳层具刚性焊合，断裂以东块体相对软弱或不同壳层之间焊合较弱，导致断裂东侧在伸展事件中具有更强烈的伸展减薄并相对沉降，在挤压事件中则具更强烈变形和更大幅度抬升，且断裂以东具多期花岗质岩浆活动，而断裂以西无花岗岩发育；溆浦—靖州断裂为扬子陆块与东南缘岛弧之间的分界断裂，是武陵（晋宁）运动中扬子陆块与东南侧岛弧的弧-陆碰撞带内主断裂。

关键词：活动历史；构造属性；伸展；逆冲；走滑；弧-陆碰撞；溆浦—靖州断裂；雪峰造山带

中图分类号：P542；P548 文献标志码：A

Abstract： The Xupu-Jingzhou fault with NNE- to NE-nearly EW-trending stirkes and SE-dipping direction is an important fault in Xuefeng orogenic belt with long-term activity. The evolutionary history and structural attribute of Xupu-Jingzhou fault through fault-related sedimentation， deformation and magmatism were studied. The results show that the fault experienced several tectonic movements， which are Nanhuan Period extension， Late Silurian Caledonian thrusting， Late Paleozoic extension， Late Middle Triassic Indosinian thrusting， left-lateral slipping-thrusting during Late Triassic-Middle Jurassic， Late Middle Jurassic Early Yanshanian thrusting， Cretaceous extension and Paleogene dextral strike-slipping from early to late； the block in the

west side of Xupu-Jingzhou fault is stronger or with inflexible coupling between different layers， while the block in the east side of Xupu-Jingzhou fault is softer or with weak coupling between different layers； because of the structural difference of the crustal basements， there are more intensive extension， thinning and subsidence under extensional setting， and stronger folding， thrusting and larger uplift under compressional setting， and several granitic magmatism in the east side of Xupu-Jingzhou fault； Xupu-Jingzhou fault is the boundary between Yangtze Block and the southeastern island arc， and is the major fault in the arc-continental collision zone during Wuling （Jinning） movement.

Key words： activity history； tectonic attribute； extension； thrusting； strike-slipping； arc-continental collision； Xupu-Jingzhou fault； Xuefeng orogenic belt

0 引 言

作为江南造山带西段的雪峰造山带是华南构造演化中一个重要的地质单元。前人对其形成演化和构造属性[1-13]、构造变形特征[14-27]、内部中生代盆地特征和成因[28-32]等进行了大量研究，但在造山带结构组成、构造变形与构造隆升的时代等问题上仍存在认识分歧[1，7-8，14，17，20]。……