- 责任者：Xu Yaoming (State Key Laboratory for Mineral Deposits Research ; School of Earth Sciences and Engineering ; Nanjing University ; Nanjing 210093 ; China) ; Jiang Shaoyong
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(12)
- 关键词：矿集区 ; ore-concentrated area ; 铜矿 ; copper ores ; 酸性岩 ; acidic rocks ; 江西 ; Jiangxi Province
- 页码：p.4291-4310
- 图表：9 illus., 5 tables, 58 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
The major types of copper polymetallic ore deposit in Jiurui ore district include porphyry, skarn and massive sulfide types. Porphyry and skarn types are typical magmatic-hydrothermal deposits, and the massive sulfide deposits of Jiurui area occurred along the strata near the sandstone and dolomite boundary but also located near intrusive rocks, which shows that magmatic-hydrothermal fluids may have also played a crucial role in the mineralization processes. In Jiurui area, petrographic characters of ore-barren intrusive rocks are almost the same as ore-bearing samples, and parameters to identify between ore-bearing and ore-barren intrusive rocks as well as how these parameters affect mineralization are still unknown. In order to solve above problems, a detailed study on geochronology, major elemental geochemistry and mineral chemistry was performed for the ore-bearing and ore-barren quartz diorite-porphyrite and granodiorite porphyry from the Jiurui ore district, Jiangxi Province. Zircon U-Pb dating results demonstrate that extensive magmatism was coeval and intensive in this area, with emplacement ages of 138.21.8Ma to 148.01.0Ma for the ore-bearing intrusive rocks, and 139.01.3Ma to 149.63.0Ma for the ore-barren intrusive rocks, which are consistent within the error range with each other. The variation ranges of SiO2 and other 9 major oxides are quite similar between ore-bearing and ore-barren intrusive rocks. The average temperatures of ore-bearing and ore-barren intrusive rocks are 769℃ and 723℃ respectively, which are also not much difference. However, the variation range of the ore-bearing intrusive rocks （580~915℃） is obviously greater than the ore-barren ones （656~796℃）. It is remarkable that the average pressure of ore-barren intrusive rocks （5.7kbar） is evidently greater than the ore-bearing samples （1.4kbar）. Therefore, the ore-bearing intrusive rocks from the Jiurui area should have experienced a more distinctive pressure decreasing process, which is quite important to form magmatic aqueous phase and brittle failure for hydrothermal circulation. However, decreasing pressure process of an intrusive rock is not the sufficient condition for mineralization, but a necessary condition. Based on the data from Jiurui area, the mineralization potential is weak when the pressure of intrusive rock exceeds 4kbar. The fO2 of the ore-bearing intrusive rocks has a wider variation range than the ore-barren samples and half of the data are plotted above the HM buffer line, but the fO2 data of the ore-barren samples are all plotted below the HM buffer line, which means that high fO2 （higher than HM buffer line） is beneficial to mineralization in Jiurui ore district.