甘肃北山白墩子—小西弓韧性剪切带及其控矿作用  

BAIDUNZI-XIAOXUGONG DUCTILE SHEAR ZONE AND ITS ORE-CONTROLLING EFFECT IN THE SOUTHERN BEISHAN AREA,GANSU

作　　者：陈柏林[1] 吴淦国[2] 杨农[1] 叶得金[3] 舒斌[1] 刘晓春[1] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地质大学(北京),北京100083 [3]甘肃省地质调查院,甘肃兰州730000

出　　处：《地质力学学报》2007年第2期99-109,共11页Journal of Geomechanics

基　　金：原地质矿产部定向研究基金项目(编号:地科定96-21)资助

摘　　要：白墩子-小西弓韧性剪切带是甘肃北山地区8条韧性剪切带中最南侧的一条，位于北山南带的白墩子-小西弓-带，呈近东西向展布，长160km，宽5～8km。该韧性剪切带以近水平右行剪切为特点，是一条形成于中低-中偏高温度、较低差应力条件（53～106MPa）下的韧性剪切带，主应变（Rxz）为4～20，剪应变（γ）1．41～2．42，剪位移达10～25km。该韧性剪切带对金矿床控制作用明显，在区域上控制金矿床（点）的分布，在矿床范围内控制金矿化带、矿体的形态、产状和规模。压扭性韧性剪切变形特点决定了金矿化类型以蚀变糜棱岩型为主，蚀变以交代作用为特色。金矿化稍晚于韧性蛮形。The Baidunzi-Xiaoxigong ductile shear zone, as the southernmost one of the eight ductile shear zones in the Beishan area, Gansu, is situated at the southern border of the southern Beishan area and near the northern border of the Dunhuang massif. It extents in a nearly E-W direction with a length of 160 km and a width of 5-8 km. This shear zone is characterized by subhorizontal dextral shear and formed under the conditions of low-middle to middle-slightly high temperatures and relatively low differential structural stresses （53-106 MPa）. The principal strain （Rxz） is 4-20, the shear strain （7） is 1.41-2.42 and the shear displacement is up to 10-25 km. The ductile shear zone has a marked controlling effect on gold deposits ： it controls the distribution of gold deposits （occurrences） on a regional scale and the shape, attitude and size of gold mineralization zones and orebodies on a deposit scale. The features of transpressional ductile deformation determine that gold mineralization is mainly of altered mylonite type and that alteration is featured by metasomatism. Gold mineralization occurred a little later than ductile shear deformation.

关 键 词：韧性剪切带 变形特征 控矿作用 自墩子-小西弓-带 甘肃省 

分 类 号：P618.41[天文地球—矿床学] P613[天文地球—地质学]