摘要
本文通过研究鲁西平邑磨坊沟金矿矿层 ,详细研究了围岩蚀变特征和成矿流体特征 ,结合硫、氧同位素资料 ,探讨了该矿床的成因机制。磨坊沟金矿呈似层状产于新太古代花岗闪长岩或古元古代二长花岗岩与寒武系主拆离滑脱带之上的早寒武世朱砂洞组碳酸盐岩中 ,围岩蚀变包括黄铁绢英岩化、方解石化和萤石化 ,金矿的形成主要与黄铁绢英岩化有关。成矿流体的均一温度集中于 10 3～ 2 2 0℃之间 ,盐度在 4 .6 5 %～ 13.18%范围内。从矿物成分看 ,该矿床属于碲金型金矿。同位素研究表明 ,矿层中硫来源于地幔 ,而氧同位素则显示其成矿过程有大气降水的参与。矿质迁移经过了鲁西幔枝构造中深、浅层次的拆离滑脱构造 ,最终卸载于次级拆离滑脱带断坪和断坡中。
This paper described the measured section ofthe Mofanggou golddeposit, studied in detail characteristics of alterations and fluid inclusions as well as stable isotopes, and discussed the formation mechanism of the deposit.The Mofanggou gold deposit, stratoid in form, occurs in Early Cambrian Zhushadong Formation which overlies the principal detachment-slip zone between Cambrianstrata and Archaeozoic gneissose granodiorite or Palaeoproterozoic adamellite. Wall-rock alterations include kaolinization, pyritization, silicification, sericitization, calcitization and fluoritization. Gold ores are related to pyritization, silicification and calcitization. Gold minerals are native gold, petzite andelectrum. The homogenization temperature of the fluid inclusions mainly rangesfrom 103 ℃ to 220 ℃. The salinity varies from 4.65% to 13.18%. Sulfur isotope studies demonstrate that sulfur was derived from the mantle, and oxygen isotope analyses reveal that the fluid of the deposit was a mixed source of magmatic water and atmospheric water. The ore-forming fluids originated from the multipleevolution of North China sub-mantle plume, migrated through deep and shallow detachment-slip zones of Luxi mantle-branch structure, and were eventually unloaded in flats and ramps of secondary detachment-slip zones.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2004年第5期523-528,共6页
Acta Geoscientica Sinica
基金
中国地质调查局地质调查项目 (编号 :2 0 0 110 2 0 0 0 3 8)
国家自然科学基金项目 (编号 :40 2 72 0 88)
国家重点基础规划发展项目 (编号 :G19990 43 2 11)成果。
关键词
金矿
矿层
围岩蚀变
成矿流体
Mofanggou gold deposit tellurium-gold type detachment-slip zone mantle-branch structure
