云南墨江金矿含镍金绿色蚀变岩的构造地球化学特征及时空演化  

CHARACTERISTICS OF TECTONIC GEOCHEMISTRY AND SPATIAL-TEMPORAL EVOLUTION OF GREEN Ni-Au-BEARING ALTERED ROCKS IN MOJIANG Ni-Au DEPOSITS, YUNNAN

作　　者：方维萱[1] 胡瑞忠[2] 漆亮[2] 谢桂青[2] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学开放研究实验室,贵州贵阳550002 [2]有色金属矿产地质调查中心北京地质调查所,北京100814

出　　处：《矿物学报》2004年第1期31-38,共8页Acta Mineralogica Sinica

基　　金：国家重大基础研究规划项目(G1999043200);国家杰出青年科学基金项目(49925309)

摘　　要：采用构造变形筛分、同位素地球化学定年约束和构造蚀变岩的常量 微量元素地球化学研究等方法,对墨江镍金矿床中含金镍绿色蚀变带进行详细研究,探讨其形成和时 空演化规律,以及与金、镍成矿关系,提出本区含镍金绿色蚀变带形成与演化可分为三个期次:早期含镍金绿色蚀变带形成于(251 9±4 32)Ma,产于韧性剪切带中,形成含铬绢云母 绢云母(S2)组成的切层剪切面理;中期含镍金绿色蚀变岩形成于燕山早期(169 37～180 6Ma),产于高角度脆韧性剪切带中,形成铬绢云母 含铬绢云母组成的透入性剪切面理换(S3)和绿泥石拉伸线理;晚期含金绿色蚀变糜棱岩形成于燕山晚期(71 14～149 98Ma),产于左旋走滑脆韧性剪切带中,发育铬伊利石(S4)和铬绿泥石(S4)组成透入性剪切变形面理置换,与脆韧性剪切带的主体产状一致,韧性剪切构造带内发育,走滑构造带中十分发育,形成褶皱变形带(倾竖褶皱、鞘褶皱)及含金蚀变岩。Based on the analysis of tectonic deformation and isotopic geochemical constrains, the geochemical study of trace and major elements, characteristics of tectonic geochemistry and spatial-temporal evolution, the blue altered rocks in the Mojiang Ni-Au deposits have been discussed in detail. The first-stage blue Ni-Au-bearing altered rocks hosted in the brittle-ductile shear zones were probably formed at 251.9±4.32 Ma, and S-C fabric plane(S_2)in cutting bed plane(S_1) was found in this type of altered rocks. The second-stage blue Ni-Au-bearing altered rocks hosted in the strike-slip-type shear zones with a high angle were probably formed in the Early Yanshanian orogen (180.6～169.37 Ma). Transposition foliation of penetrative shear (S_3) and chlorite lineament (L_3) characterized the second-stage blue Ni-Au-bearing altered rocks. The last-stage blue Ni-Au-bearing altered rocks were most likely to have formed in the strike-slip-type shear zones during the Late Yanshanian orogen (149.98～71.14 Ma). Cr-minerals, including Cr-hydromiscovite, Cr-kaolinite, Cr-hydrokaolinite, blue Cr-kaolinite, hydrokaolinite and Cr-smectite, account for the green color of the Ni-Au-bearing altered rocks.

关 键 词：金矿 绿色蚀变岩 矿物构造 地球化学 云南 

分 类 号：P618.51[天文地球—矿床学] P544[天文地球—地质学]