肃北县德勒诺尔铁矿区构造应力场分析

TECTONIC STRESS FIELD ANALYSIS OF DELENUOER IRON DEPOSIT IN SUBEI COUNTY

本文以德勒诺尔铁矿区发育的节理为研究对象,在约20km2的研究区内布置了93个观测点,在野外共观测三百余组节理,采用数学统计方法,对节理进行分期配套,确定区内主要发育3组高倾角平面X剪节理,通过节理之间相互错断、限制关系对节理期次进行配套分析,并对不同期次构造应力场形成的共轭剪节理进行了研究,利用吴氏网绘制各观察点的主应力图解,获得各点应力轴(σ1,σ2,σ3)的产状。研究得出本区第1次构造应力场最大主压应力轴(σ1)的优选产状为181°∠8°,中间应力轴(σ2)为141°∠81°,最小主应力轴(σ3)为89°∠5°,可能是区内的主体构造格架的动力来源,在区内形成了近EW向的复式背斜及叠瓦状逆冲断裂。第2期构造应力场最大主压应力轴呈NE—SW向,最大主压应力轴(σ1)的优选产状为250°∠12°,中间应力轴(σ2)为56°∠78°,最小主应力轴(σ3)为143°∠11°,为区内形成NW—NWW向展布的逆冲断裂的主要动力来源。第3期构造应力场最大主压应力轴呈NNW—SSE向,最大主压应力轴(σ1)的优选产状为344°∠3°,中间应力轴(σ2)为79°∠80°,最小主应力轴(σ3)为252°∠13°,可能为区内NW、NE向展布的张性断裂的主要动力来源。研究总结了区内不同期次构造应力场的特征,并对动力来源进行了初步探讨。

This article takes joint as the object of the research in delenuoer iron deposit,the layout of the 93 observation points in the research area of about 20 km2,where were observed more than 300 sets of joints,adoption mathematical statistics to match by stage for determining the area mainly developed 3 sets of high inclined plane X shear joint.Through the fault、limitation of the joints to analyse of matching on joint time,according to the tectonic stress field of the different stages formed in the conjugate shear joints were studied,using Wulff net mapping from the main stress diagram of each observation point,to obtain the stress axis（σ1,σ2,σ3） occurrence.It is indicated that the maximum principal compressional stress axis of the first tectonic stress field（σ1） preferred occurrence is 181°∠8°,the middle axis of stress（σ2） is 141°∠81°,the minimum axis of stress（σ3） is 89°∠5°,maybe the power source of the main tectonic framework is formed synclinorium and imbricated thrust fault of a nearly EW in the region.Maximum principal compressional stress axis（σ1） of the second tectonic stress field is along NE-SW,preferred occurrence is 250°∠12°,the middle stress axis（σ2） is 56°∠78°,the minimum principal stress axis（σ3） is 143°∠11°,it is the main power source of NW-NWW trending thrust fault.Maximum principal compressional stress axis（σ1） of the third tectonic stress field is to NNW-SSE,which preferred occurrence is 344°∠3°,the middle stress axis（σ2） is 79°∠80°,the minimum principal stress axis（σ3） is 252°∠13°.Possible for the main power source of extension fracture in NW,NE.Summary of research in the area of different periods of tectonic stress field characteristics,and the power source are discussed.