摘要
雪峰山中段金矿区内NE向和NW向主要控矿断裂带的宏观地质、显微构造和构造地球化学特征表明 ,NW向断裂为NE向断裂的伴生或派生构造的构造带。NE向断裂的声发射法、动态重结晶石英粒度法、石英亚颗粒法等变形岩石差应力估算值在 42 .39～ 6 8.40MPa之间 ;而NW向断裂带则介于 2 7.44～ 5 3 .14MPa之间。声发射法、包裹体测压法推测控矿构造韧性变形时的形成深度为 3 70 4～ 5 0 86m ,脆性变形时为 375～ 2 944m。岩组分析说明 ,NE向断裂具有早期逆冲推覆 ,主压应力属NW—SE向应力系统 ;晚期正断滑覆 ,应力方位偏转到SSE—NNW向。
The major structures in the gold ore district in Middle Xuefeng Mountain can be divided two belts.①The NE trending fault belt, which is composed of some parallel Caledonides faults. They were active in Indosin Yanshanian epoch and belong to Xuefeng Mountain arcuate ductile shear zone. They are distributed in parallel in plan and in imbricate arrangement in profile. There exist mylonite and silicatized gold alteration and they are major ore passageway structures in this region. This belt belonged to the structural phase ductile shear zone at the early stage, which was composed of a set of ductile deformation masses. Later it uplifted and formed a set of poor structural phase brittle ductile deformations. ②The NW trending fault belt. It is composed of schistosity zone, silicated vein zone,fracture zone and is distributed among NE trending fault belts. It was formed later than the NE trending fault belt,i.e., during the late ductile deformation stage or later. It is characterized by similar distance in plan and ribbon form in section. They are major host structures, which control the Tangwan Chanziping metallogenic belt, the Zimucao Tongxi Liangxikou Daping metallogenic belt, the Taojinkeng Baiyanyun Shuikoushan metallogenic belt and the Guanyintian Xiangjiatian metallogenic belt. Based on an analysis of macrostructures, microstructures, tectonite and structural geochemical features,it is inferred that the NW trending faults are the associated or induced structural belts of NE trending faults. The differential stress values of NW trending faults are between 42.39 and 68.40 MPa measured by echo emotion, dynamic recrystallized quartz grains and quartz subgrains, while those of NE trending faults are between 27.44 and 53.14 MPa. The depths of ductile deformation of ore controlling structures are about 3 704～5 086 m and the depths of brittle deformation are about 375～2 944 m. Petrofabric analysis shows that polar projection of chlorite and quartz in NE trending faults are mainly horizontal big circle and density, and major density or dot density parallel or vertical to the kinematic main axis. Dynamic features show that the NE-trending faults thrusted at the early stage and their main stress belongs to NW—SE stress system, but at the later stage they were normal faults and the main stress orientation changed to SSE—NNW or SN trending.It is also shown that the major stress orientation that formed the NW-trending fault was NE—SW and NNE—SSW trending,and it changed to SN and NW—WE trending after the formation of the ore deposits.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2001年第2期117-122,共6页
Acta Geoscientica Sinica
基金
国家计委"黔阳地区金锑矿控矿条件及靶区优选"专题研究及国土资源部地质力学开放实验室基金!资助项目研究成果的部分内容
