辽东半岛大石桥周家铁钴矿控矿构造特征及其区域地质意义

Structural controlling characteristics of the Zhoujia Fe-Co ore deposit and regional geological significance in Dashiqiao,Liaodong Peninsula

构造作用往往能为成矿流体提供重要的导矿通道,以此对矿床的形成及富集起着关键的控制作用,对其进行深入的研究能为地质找矿提供理论依据。本文对中国东北地区辽宁大石桥市周家铁钴矿开展了详细的地质工作,包括剖面测制、构造解析和岩相学观察等。野外观察及室内岩相学研究指示Fe-Co矿矿体主要赋存于里尔峪组二段变粒岩和浅粒岩中。此外,还有少量铁矿见于古元古代辽吉花岗岩中。构造解析显示周家Fe-Co矿围岩变形包括早期紧闭褶皱、逆冲断层以及断层相关褶皱和晚期布丁构造、倾竖褶皱。通过野外岩脉穿切关系并综合前人年代学资料,可以将周家铁钴矿形成过程分为三个阶段,早期发生原始地层变形,即为S_(0)发生变形形成S_(1)和F_(1)阶段;中期逆冲断层及紧闭褶皱等产于强烈造山期的构造要素为周家铁钴矿在古元古代的富集成矿提供了重要的构造条件;周家铁钴矿最终构造样式为倾竖褶皱和布丁状铁矿体,形成于晚期古元古代造山后的抬升剥蚀。

Structure often serves as a crucial pathway for ore-forming fluids,playing a pivotal role in controlling the formation and enrichment of ore deposits.Investigation structural evolution can provide a theoretical foundation for geological prospecting.This study detailly examines the Zhoujia Fe-Co deposits in Dashiqiao City,Liaoning Province,Northeast China through profiling,structural analysis,and petrographic observation.Field observations and laboratory petrographic studies indicate that Fe-Co ore bodies primarily occur within the leucoleptite and leptynite of the second segment of the Li'eryu Formation.A small amount of iron ore is also found in the Paleoproterozoic Liaoji granite.The structural analysis reveals that the deformation of surrounding rocks at Zhoujia Fe-Co mine includes early tight folding,thrust faulting,fault-related folding,as well as late pudding structures and plunging vertical folds.Based on field dike-cutting relationships and previous geochronology data synthesis,the Zhoujia Fe-Co deposit formation can be divided into three stages.In the early stage,initial formation deformation occurred,resulting in the development of S_(0) deformation into S_(1) and F_(1) stages.During the middle stage,thrust faults and tight folds,which were generated during a period of intense orogeny,provided crucial structural conditions for the enrichment and mineralization of the Zhoujia Fe-Co deposit in the Paleoproterozoic.The final structural pattern observed at the Zhoujia Fe-Co deposit,including vertical folds and boudinage iron ores,was formed during exhumation and denudation processes associated with late Paleoproterozoic orogeny.