摘要
两矿床均主要由糜棱岩型矿石组成,受韧性剪切带控制,金矿化与强硅化和金属硫化物的富集有关。但两矿床的物质组成和稳定同位素特征并不完全相同,其中云西矿床矿物组合较复杂(富含磁黄铁矿等)、矿石化学成分中钴和镍含量较高、铅同位素组成范围较窄(μ值较小、φ值年龄较大),反映两矿床的物质来源和形成环境有差异。推测与不同的重熔岩浆热液作用有关。
Hetai goldfield, located in the Yunkal Mountain of western Guangdong, is composed of a group of large, medium, and small gold deposits. They generally occur in the altered mylonite zones composed of deformed Sinian metamorphic rocks and are mainly controlled by ductile shear belts. There are two generations of the gronitoids which consist mainly of gronodiorite (Yunlougang body) and megaphyric monzonitic granite (Wucun body), respectively.The gold deposits of the Gaocun mine and Yunxi mine situated at the north of the goldfield are large deposits hosted in the ML-11 and ML-19 mylonite zones respectively. Gold mineralization is mainly related to strong silicification during the ductile shearing and later enrichment of the metallic sulphides.The mineralogical and chemical compositions and stable isotopic constitutions of the two deposits are not quite the same. For instance, the Yunxi deposit is higher in Co and Ni contents and is more camplicated in its mineral assemblage. It also contains more pyrrhotite and rarely also pentla-ndite and is characterized by a more limited range of the Pb isotope constitution with smaller μ values and older model ages. These features indicate their differences in metallogenic environment and source of material.On the contrary, the hydrogen and oxgen constitutions of the two deposits are substantially identical. Measured and calculated δD and δ18O values of the hydrothermal fluids are -73.9--91.4‰ and +3.2-+6.31‰, respectively. These values roughly indicate that the fluids are basically of magmatic hydrothermal nature mixed with a small amount of meteoric water (Talor, 1974).Consequenlly, both Gaocua mine and Yunxi mines are considered to be magmatic hydrothermal deposits controlled by ductile shear belts. The mineralization of the Yunxi deposit is probably related to a later hydrothermal process of the Yunlongang intrusion with multiple magmatic activities, whereas the Gaocun deposit is perhaps closely related to the late hydro-thermal activity of the Wucun body.
出处
《地球学报》
EI
CAS
CSCD
1991年第1期101-116,共16页
Acta Geoscientica Sinica
