摘要
产于麋棱岩带的河台金矿是一种新的金矿类型。地质及地球化学研究表明主要控矿因素有:①矿源层(含金建造)——提供金的来源;②混合岩化及花岗岩岩浆热液作用——促使金发生活化转移;③韧性剪切带——提供了导矿通道及容矿空间。矿床形成于中温(250℃)、中深(573.5×10~5Pa)的条件。成矿流体富含HCO_3-及CO_2,并具Na^+>K^+>ca^(2+),HCO_2^->C1^->F^->ΣS,CO_2>CH_4的特点。介质从早到晚由中性到弱碱性,氧逸度f_(o2)为10^(-37)-10^(-39)。矿床是多阶段长期演化发展的产物,区域变质作用,动力变质作用,混合岩化作用过程中变质热液起着主导作用,海西—印支期断裂重熔岩浆热液活动使金局部富集。在此认识基础上,提出了河台金矿的成矿模式。
The Hetai gold deposit is located in Yunkai Mountain of western Guangdong, which is an important gold prospect area in South China. Based upon a detailed study on gold-bearing formation, two types of migmatite and characteristics of the gold deposit, the authors hold that the Sinian C Formation(Z^c) is the most important gold-bearing formation in this area, which provided the Hetai gold deposit with large quantities of ore materials. The regional metamorphism and basement migmatitization accompanying Yunan orogeny caused the activation and transference of gold in the gold-bearing formation. Later, a further enrichment of gold took place in the fractural-metamorphic migmatite zone during the fractural metamorphism, and the Hercynian-Indosinian granitic activities once again stimulated the activation and enrichment of gold. The muscovite pegmatite, an evolution product of the granite, is closely related to orebodies in space, time and genesis. The Sihui-Wuchuan fault and its secondary faults have been repeatedly activated since the Caledonian orogeny. in profile, the gold deposit is strictly controlled by the mylonite zone and displays obvious zoning. From the wall rock to the orebody, gold and other metallogenic elements increase gradually. The ore-forming solutions are characterized by Na^+>K^+>Ca^(2+)>ΣFe>Cu^(2+), HCO_3^->C1->F->S^(2-) and CO_2>CH_4, the ore-forming temperature is 200-280℃, ore-forming pressure about 566 atm(573 x 10~5Pa), and of_2, 10^(-37)-10^(-39). Gold and major cations and anions in ore-forming solutions increase steadily from early stage to late, and the isotopic evidence demonstrates that the ore-forming solutions are mixtures of metamorphic and meteoric waters, with the participation of a little magmatic water.
出处
《矿床地质》
CAS
CSCD
北大核心
1989年第2期61-71,共11页
Mineral Deposits
