摘要
从湖南万古金矿区采集4件石英样品进行了氦同位素测定,获得了~3He/~4He值231×10^(-6)—1460×10^(-6)的数据。该数据反映了在万古金矿床形成时富~3He流体参与了成矿作用。而这种富~3He流体可能是受构造活动影响,由地幔岩石减压部分脱气造成动力学分馏而形成。
The Wangu gold deposit, a new discovery in the past six years, is one of representative gold deposits in the gold deposit belt of the Jiangnan massif in the Yangtze Platform. There are 19 nearly E-W-trending ore veins hosted in the Middle Proterozoic slate in the deposit. Gold mineralization is controlled by a group of E-W-trending fractures, which are subsidiary ones of the Si-cun - Tadong regional fault of ENE strike. The ores in the deposit can be divided into quartz vein, fractured slate and breccia types. Four samples of quartz separately taken from No. 1 and No. 5 ore veins were analyzed by the noble gas spectrometer in the Stable Isotope Laboratory of the Institute of Mineral Deposits, Chinese Academy of Geological Sciences, which was imported from Ukraine. The 3He/4He data taken range from 231 X 10-6 to 1460X 10-6.According to related researches, meteorite, moon rock and solar wind have higher 3He/4He values ranging from 370×10-6 to 426×10-6. The 3He/4He values of marine basalt, hydrother-mal solution in the Liohi Sea Mount and in the Red Sea are around 12 × 10-6-17. 2 × 10-6. O'Nions et al (1994) pointed out that the 3He/4He value of upper mantle is 12 × 10~6-42 × 10-6. In general, the 3He/4He value of the air is 1. 4×10-6, that of the Crust is nx 10-6, and that of granite is 1 % of that of the air . Compared to the 3He/4He distribution in various kinds of rocks and fluids, the helium in the Wangu gold deposit might be derived from the mantle. This result is in accordance with the writers' previous study on stable isotope determination of sulphur, oxygen, and hydrogen.A series of NE-trending regional faults formed in eastern China due to subduction of the Pacific plate to Eurasia continent during the Mesozoic. These large faults led the hydrothermal fluids, heat energy, and some substances move upwards along them. The Sicun - Tadong fault beside the Wangu gold deposit is a part of the large NNE-trending Guangji - Litang fault which is possible to be connected with the Tancheng -Lujiang huge strike-slip fault in its north. Furthermore, a great amount of accumulation of helium gas has been discovered in several basins such as the Songliao, Liaohe, North Jiangsu and Sanshui basins, distributed along the Tancheng-Lujiang fault .
出处
《地质论评》
CAS
CSCD
北大核心
1997年第6期646-649,共4页
Geological Review
关键词
金矿床
地幔流体
氦同位素
矿床成矿
gold deposit, mantle fluid, helium isotope, Wangu, Hunan
