摘要:
提要: 云南昭通大型铅锌矿是滇东北矿集区乃至川滇黔铅锌成矿域铅锌矿床的典型代表。矿床具有明显的矿物组合分带性的特点, 区别于典型的MVT型铅锌矿床。根据矿物组合特征构建、计算、绘制了该矿床的pH?logfo2、pH?loga相图, 剖析了铅锌矿共生分异的形成机理。研究表明pH、氧逸度、组分浓度的协同作用造成了铅、锌的共生分异, 对矿物组合分带起控制作用, 且温度下降、氧逸度升高和pH升高有利于金属硫化物的沉淀, 成功解释了昭通铅锌矿床独具特色的矿物分带地质特征。
Abstract:
Abstract: Located at the southern center of the Sichuan-Yunnan-Guizhou lead-zinc polymentallic mineralization domain on the southwestern margin of the Yangtze block, the Zhaotong lead-zinc deposit in Yunnan Province is a typical representative in northeastern Yunnan or even in Sichuan-Yunnan-Guizhou area. The deposit is characterized by vertical zoning from coarsegrained pyrite, dark-color sphalerite + ferro-dolomite + quartz, rosy sphalerite + galena + pyrite to fine-grained pyrite from bottom to top of the orebody. These typical features are different from known lead-zinc deposit types discovered both in China and abroad, such as Mississipp Valley Type (MVT), Volcanic Hosted Massive Sulfide Type (VHMS), and Hydrothermal Sedimentation Type (SEDEX). The controlling of pH, logfo2, loga over the main metal sulfides and their assembly as well as mineral zoning will contribute to solving the formation mechanism of lead-zinc association and differentiation and the extreme enrichment of elements. Metallic minerals in the mineral zoning are the main study object, and pH-logfo2, pH-loga phase diagrams of the Zhaotong lead-zinc deposit at ore-forming temperatures (373 K, 423 K, 473 K, 523 K) were drawn. On the basis of these phase diagrams, the characteristics of the mineral zoning in the Zhaotong lead-zinc deposit that are different from features of known lead-zinc deposit types discovered in the world could be explained successfully. It is believed that the association of temperature, oxygen fugacity, component concentration and pH caused the lead-zinc association and differentiation and controlled the precipitation of main metal mineral assemblages and the zonation of mineral assemblages. When the temperature drops, the logfo2 value rises, pH goes up, and the sulfide will precipitate more easily.
下载:
