Application of Thermodynamics pH-Eh to Mineral Zonation Model of Sandstone-Hosted Type Copper Deposits in the Chuxiong Basin, Central Yunnan Province, China
详细信息
- 责任者：Zhang Yan (Southwest of Geological Survey ; Geological Survey Center for Non-Ferrous Mineral Resources ; Kunming University of Science and Technology ; Kunming 650093 ; China) ; Han Runsheng
- 刊名：Acta Mineralogica Sinica
- 出版年：2013
- 卷期：33(3)
- 页码：p.363-368
- issnNo：ISSN1000-4734
- isbnNo：CN52-1045/P
摘要
Sandstone copper deposits in central Yunnan Province,China such as Liuju copper in Dayao deposit are near the light-colored side of the transition zone of purple sandstone and light-colored sandstone from Liuju sub-segment (K2ml1 ) of the upper Cretaceous.Copper mineralization is controlled by the redox interface.From purple sandstone to light-colored sandstone,metallic minerals present a horizontal zoning in order as hematite,chalcocite,bornite,chalcopyrite and pyrite.Metallic minerals in the mineral zoning were studied.Based on test results of fluid inclusion,the pH-Eh phase diagram for Dayao copper deposit at ore-forming temperature was made.Results of theoretic calculation are consistent with macro-geological characteristics.Based on pH-Eh diagram,precipitation conditions and zoning mechanism of major metallic minerals were elaborated.It is believed that metallic mineral zonage of the sandstone copper deposit in Chuxiong Basin is under the dual control of pH and Eh.Between 373 K and 523 K,temperature changes have little effect on pH and Eh of the metallic mineral precipitation.The S2 can only be stable at temperature lower than 473 K,and the formation temperature of chalcocite (Cu2S) is below 473 K.The study has provided an important basis for ore forming mechanism.