安徽南陵‒宣城矿集区昆山叠瓦式逆冲断裂带构造特征:来自钻孔和地球物理方面的新证据  

Structural Characteristics of Kunshan Imbricated Thrust Fault Zone in the Nanling-Xuancheng Ore Concentration Area,Anhui Province:New Evidence from Borehole and Geophysics

作　　者：朱强[1,2] 陆三明[1] 赵丽丽[1] 郭冬[3] 张赞赞 杨本忠[4] 韩长生 金敏 ZHU Qiang;LU Sanming;ZHAO Lili;GUO Dong;ZHANG Zanzan;YANG Benzhong;HAN Changsheng;JIN Min(Public Geological Survey Management Center of Anhui Province,Hefei 230091,Anhui,China;Geological Survey of Anhui Province,Hefei 230001,Anhui,China;Geological Exploration Technology Institute of Anhui Province,Hefei 230031,Anhui,China;East China Metallurgical Institute of Geology and Exploration,Hefei 230088,Anhui,China;No.812 Geological Team of East China Metallurgical Bureau of Geology and Exploration,Tongling 244008,Anhui,China)

机构地区：[1]安徽省公益性地质调查管理中心,安徽合肥230091 [2]安徽省地质调查院,安徽合肥230001 [3]安徽省勘查技术院,安徽合肥230031 [4]华东冶金地质勘查研究院,安徽合肥230088 [5]华东冶金地质勘查局812地质队,安徽铜陵244008

出　　处：《大地构造与成矿学》2022年第6期1229-1244,共16页Geotectonica et Metallogenia

基　　金：国家重点研发计划项目(2016YFC0600209)资助。

摘　　要：南陵‒宣城矿集区是长江中下游成矿带近年来新发现的矿集区。矿集区构造以一系列NE向褶皱‒逆冲作用为主要特征,尤以逆冲作用最显著。本次研究通过实测构造地质剖面,结合高分辨率反射地震、大地电磁测深和高精度重磁测量等方法的三维综合地球物理探测技术,查明了狸桥‒九连山地区逆冲断裂带的几何学和运动学特征,利用钻孔资料进行有效约束,首次反演了其深部结构。综合分析认为该逆冲断裂带作为茅山推覆构造南延安徽段,由一系列叠瓦式逆冲断层组成,运动形式与江苏段有一定区别,将其命名为“昆山叠瓦式逆冲断裂带”。野外证据和定年结果显示,逆冲断裂带的挤压应力方向为NW-SE向,经历了至少三期逆冲活动,分别为早中生代的印支期‒燕山早期、晚中生代的早白垩世末和晚白垩世末‒古新世,自印支期以来经历了挤压(印支期‒燕山早期)‒伸展(早白垩世初)‒挤压(早白垩世末)‒伸展(晚白垩世)‒挤压(晚白垩世末‒古新世)等多构造旋回的演化过程。虽然,逆冲活动对早白垩世初形成的矿体有一定的破坏作用,但考虑到逆冲断层较深且水平位移不大,狸桥‒九连山地区依然是矿集区内具有巨大潜力的找矿区域之一。The Nanling-Xuancheng ore-concentration area was discovered in the middle and lower Yangtze River metallogenic belt(MLYRB)years ago.The structure of the ore concentration area is characterized by a series of NE-trending folds and thrusts,especially the thrusts.Based on measurement structural geological sections and 3-Dimensional comprehensive geophysical exploration(e.g.,high resolution reflection earthquake,magnetotelluric sounding and high precision gravity and magnetic measurement),the geometry and kinematics characteristics of the thrust fault zone in the Liqiao-Jiulianshan area are identified.Borehole data are used to constraint the deep structure.A comprehensive analysis shows that the thrust fault zone is composed of a series of imbricate thrust faults as the southern extension of the Maoshan thrust structure in the Anhui section.The movement form of the thrust fault zone is different from that of the Jiangsu section,and it is named as“the Kunshan imbricate thrust zone”.Field evidence and dating results indicate that the compressive stress direction of the thrust fault zone is NW-SE.The thrust fault zone experienced at least three stages of thrust activities:the Early Mesozoic Indosinian-Yanshanian,the Late Cretaceous,and the Late Cretaceous-Paleocene.Since the Indosinian,it has experienced multi-tectonic cycles such as the Indosinian to early Yanshanian compression,the Early Cretaceous extension,the Late Cretaceous compression,the Late Cretaceous extension,and the Late Cretaceous to Paleocene compression.Although the thrust activities have a certain destructive effect on the integrity of the orebody formed at the beginning of the Early Cretaceous,considering that the deep thrust fault and the small horizontal displacement,the Liqiao-Jiulianshan area is still one of the prospecting areas with great potential in the ore concentration area.

关 键 词：狸桥‒九连山地区 叠瓦式逆冲断裂带 深部结构 多构造旋回 找矿区域 

分 类 号：P542[天文地球—构造地质学] P612[天文地球—地质学]