普朗斑岩铜矿位于三江地区义敦岛弧南端的中甸弧,是在晚三叠世甘孜.理塘洋盆向西俯冲过程中形成的一个大型.超大型矿床。通过显微测温学和激光拉曼谱学研究,发现普朗斑岩铜矿含矿石英脉中广泛发育富液相包裹体、含CO2三相/两相包裹体、含子晶多相包裹体。子晶种类复杂,盐类矿物主要有石盐、钾盐、方解石、石膏,金属矿物主要为黄铜矿和赤铁矿。流体包裹体中发现有4种流体,即高盐度岩浆流体、含CO2低盐度流体、中等盐度流体以及少量低盐度水溶液。高盐度岩浆流体的均-温度范围457,245℃,均一压力范围(259.33~25.43)×10^5 Pa,盐度为34%-54%NaCl,密度为1.12—1.07g/cm^3,富含Na、K、Ca、Cu、Fe、CO2、C1、S等成分。原始岩浆流体可能是由中酸性岩浆上升至中间岩浆房后直接出溶而成,并汇聚在岩浆房的顶部。在甘孜一理塘洋盆的俯冲过程中,岩浆流体在流体内压和洋盆俯冲所产生的主压应力场的共同作用下,可以间歇性地从岩浆房上涌,为早期岩浆活动(226±3)~(2284-3)Ma所形成的岩浆一热液系统提供了持续的矿质和热源。含CO2低盐度流体与高盐度岩浆流体的相分离作用是导致普朗斑岩铜矿主成矿期网脉状-浸染状矿化的主要原因。
The Pulang porphyry copper deposit is located in the northern part of the Sanjiang area. Tectonically, it is located in the Zhongdian arc of the southern part of the Yidun island arc. It is a large to superlarge deposit and was formed in the process of the westward subduction of the Ganzi-Litang oceanic basin in Late Triassic. Various types of fluid inclusions have been observed or identified in the quartz veins of the deposit through microthermometric study and Laser Raman microspectroscopic analysis. They include the aqueous liquid-rich inclusions, the CO2-bearing three/two phase inclusions, and the daughter mineral-bearing multiphase inclusions basically. There are many kinds of daughter minerals, including halite, sylvinite, calcite, gypsum, chalcopyrite and hematite. Four kind of fluids trapped in various inclusions have been observed, that is, high salinity magmatic hydrothermal fluid, low salinity CO/-bearing fluid, intermediate salinity fluid and minor low salinity water. The high salinity magmatic hydrothermal fluid is characterized by homogenization temperatures of 457 - 245℃, calculated homogenization pressure of (259.33 -25.43) × 105 Pa, high salinities of 34% -54% NaCl equiv. (possibly up to 70% NaCl equiv. ), density of 1.12 - 1.07 g/cm^3, and high contents of Na, K, Ca, Cu, Fe, CO2, S and Cl. It is believed that the original magmatic fluid could be formed in the magma chamber due to the evolution of the intermediate-acidic magma, and then concentrated in the top part of the magma chamber. In the westward subduction process of the Ganzi-Litang oceanic basin, the magmatic fluid could be pulsatively upwelling, from the chamber under the fluid internal pressure and the main compressive force of the oceanic basin subduction, to provide continuous supply of ore-forming materials and heat source for the magmatic bydrothermal fluid system which was formed in the early magmatic movement during 226 ± 3 to 228 ±3 Ma. It is also believed that the phase unmixing of the high salinity and CO2-bearing