摘要
该矿床不同阶段脉石英δ^(18)O值稳定在16‰±,计算的δ^(18)O_(H_2O)达8‰±;脉石英包裹体δD_(H_2O)产值稳定在-60‰±。从地表向不同深度,直到1200m以下,蚀变岩石δ^(18)O值从15‰±,逐渐降为11‰±。各种水-岩交换计算表明,成矿流体是大气降水与千枚岩在350℃和有效W/R值为0.1左右时形成的,当它进入上部矿化体系线形水-岩交换时,有效W/R值增大为5.0以上。进而建立了缓冲开放体系两阶段水-岩交换演化成矿模式。
The large-scale Yingshan vein and disseminated Cu-Pb-Zn Ag-Au deposit occurs in the contact-fracture zone of Proterozoic phyllite and Mesozoic subvolcanic rocks. δ18O values of 12 vein quartz samples in 2 stages are very constant, ranging from 15. 3‰ to 17. 2‰ with an average of 16. 1‰±0. 6‰- The calculated δ18O values of water, which is equilibrated with main-stage quartz at 280℃ , are 8. 0‰ ±0. 6‰. δDH2,ovalues of 5 fluid inclusions of vein quartz of the main mineralization stage are from - 53‰ to - 66‰ and average around -57‰- The δ18O values of 17 altered Proterozoic phyllite samples from the Shuangqiaoshan Group range from 13. 5‰ to 16. 7‰ , with an average of 14. 9‰±0. 8‰, which are higher than that of the fresh phyllite (≈ 12. 3‰) > δ18O values of 6 altered Mesozoic subvolcanic rocks range from 11. 0‰ to 16. 8‰ , with an average of 13. 6‰±1. 9‰, which are higher than that of the fresh rocks (≈8. 5‰) on the surface. The δ18O values of two kinds of altered rocks decrease downwards to different depths until they are lower than those of fresh rocks.These features mentioned above indicate that the ore fluids are of meteoric origin, i. e. the ore fluids were formed by the interaction between Mesozoic meteoric water (δwf = - 9. 0‰, - 60‰) and the phyllite (δ= 12. 0‰, -95‰) following subvolcanic intrusion. According to the characteristics and variation of δ18O values of the two kinds of altered rocks from the surface and different depths combined with the inversion calculation, a buffered two-step mineralization system of water-rock interaction for the formation of the Yingshan deposit is proposed by this study.During the first step, meteoric groundwater was heated and then interacted with the phyllite at the >5 km depth, where t≥350℃ and the effective W/R ratio was low (0. 1-0. 01). After the areal-type water-rock interaction the original meteoric groundwater evolved into hydrother-mal ore fluids, and then a moving hydrothermal reservoir origina
出处
《地质学报》
EI
CAS
CSCD
北大核心
1996年第1期48-60,共13页
Acta Geologica Sinica
基金
国家自然科学基金(编号 49473176)
地质行业基金(编号 89042)
关键词
氢
氧
同位素
水岩体系
铜矿床
铅锌矿床
H and O isotopes, water/rock exchange, buffer open system, Yingshan of Jiangxi Province
