黔东北地区构造作用对萤石成矿的控制与影响

Controlling function and influence of tectonic actions on the fluorite mineralization in the northeastern Guizhou,China

黔东北地区与黔中隆起相邻,受黔中隆起影响与控制,该区自古生代以来经历了郁南运动、都匀运动、广西运动和燕山运动。早古生代早期发育在奥陶系下统红花园组(O_(1)h)和桐梓组(O_(1)t)脆性灰岩中的NW向裂隙是黔东北萤石矿床的容矿构造,而NE向断层属于导矿构造。本文通过区域构造研究,典型矿区的构造解析,面理、线理、节理等统计与赤平投影分析,对黔东北地区构造变形与萤石矿床的成因关系开展了研究。结果表明,寒武纪末-早奥陶世早期的郁南运动、晚奥陶世-早志留世都匀运动形成了容矿与导矿构造。早古生代末期的广西运动使得黔东北长期(石炭纪-二叠纪)处于隆升暴露,在此期间,在下古生界形成了以正断层为特点的断层组合,发育了地垒式、地堑式、阶梯状、放射状、羽裂状等多种断层组合,这些组合断层在上覆上古生界的地层中不发育。同时,下古生界还发育了切割寒武系-志留系地层的NW向断层,这些NW断层不是控矿断层,在上述研究基础上,拟定了该区控矿和不控矿的NW向断层的特征。燕山运动在黔东北形成隔槽式褶皱组合,早期断层在此期间大多反转或平移,少数继承性再活动切穿上覆二叠系-三叠系地层。总体而言,黔东北地区萤石矿化受古生代早期构造活动控制,属热液充填型萤石矿床,而广西运动、燕山运动仅对早期形成的矿床发生改造与破坏。

The northeastern Guizhou region is adjacent to the central Guizhou Uplift.Under the influence and control of the central Guizhou Uplift,this area had undergone influences of the Yunan,Duyun,Guangxi and Yanshanian movements since the Paleozoic Era.The NW-trending fissure developed in brittle limestones of the Early Paleozoic Ordovician Honghuayuan(O_(1)h)and Tongzi(O_(1)t)formations is the ore-bearing structure of fluorite deposits in the northeastern Guizhou,while the NE-trending fault is the ore-conducting structure.In this paper,the genetic relationship between the tectonic deformation and the genesis of fluorite deposits in the northeastern Guizhou has been studied through the study of regional structures,the analysis of typical structures in deposits,and the statistical analysis and eraplanation projection of foliations,lineations and joints.The results show that the Late Cambrian-Early Ordovician Yunan Movement and the Late Ordovician-Early Silurian Duyun Movement resulted in the formmation of ore-bearing and ore-conducting structures in the northeastern Guizhou.The Guangxi movement occurred at the end of the Early Paleozoic had resulted in the uplifting and exposing of the northeastern Guizhou for a long time(Carboniferous to Permian).During this period,normal fault associations were formed,and various fault associations,such as the horst,graben,staircase,radial and pinnate faults,were developed in the Lower Paleozoic strata.These faults were not developed in the overlying Upper Paleozoic strata.At the same time,the NW-trending faults cutting the Cambrian and Silurian strata were developed in the Lower Paleozoic strata,these NW-trending faults were not ore-controlling faults.On the basis of above researches,we have drawn up characteristics of the ore-controlling and not ore-controlling NW-trending faults in the area.The Yanshanian movement resulted in the formation of the trough-like fold association in the northeastern Guizhou.Most of the early formed faults were reversed or shifted during this period.Only a few reworked early faults by the inheriting reactivity had cut the overlying Permian-Triassic strata.In general,the fluorite mineralization in the northeastern Guizhou was only controlled by the early Paleozoic tectonic activities,and the fluorite deposits belongs to the hydrothermal filling type fluorite deposit.The Guangxi and Yanshanian movements only resulted in the transformation and destruction of the early formed deposits.