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红山铜矿床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中型规模的矽卡岩矿床。通常,矽卡岩体就是铜矿体或铜矿化体,主要呈似层状、层状、脉状及透镜体状产于大理岩与角岩接触带或局部在角岩中,未见其与侵入岩直接接触。通过对不同成矿阶段所形成的石榴石、磁铁矿、磁黄铁矿、黄铁矿、黄铜矿、方解石等典型矿物以及大理岩的稳定同位素特征研究,发现矽卡岩的最主要组成矿物石榴石的δ~(18)O_(SMOW)范围为6.2～8.3‰,反映了矽卡岩可能直接继承隐伏斑岩体的氧同位素组成。根据磁铁矿的氧同位素组成(5.5～7.1‰)所计算的磁铁矿化阶段成矿流体的δ~(18)O_(SMOW)为13.1～14.7‰(400℃)或12.5～14.1‰(500℃),暗示有富集δ~(18)的 CO_2溶入到成矿流体中。硫化物的δ~(34)S_(CDT)范围4.45～6.20‰,说明矿床具有高度均一的硫源,并且在硫化物的结晶沉淀过程中,流体中硫同位素分馏很弱。由此推测主成矿期成矿流体的δ~(34)S_(ΣS)为5.6±0.6‰。矿床中的大理岩的δ~(13)C_(PDB)为2.0～2.2‰,δ~(18)O_(SMOW)为24.0～24.8‰,说明大理岩是由海相碳酸盐岩经重结晶作用而成。成矿晚期阶段形成的方解石脉的δ~(13)C_(PDB)范围是-2.4～1.7‰,δ~(18)O_(SMOW)范围是16.3～22.4‰,表明其 C 和 O 主要来源于大理岩。总之,我们推测红山矽卡岩很可能主要是由中酸性岩浆浅成侵位时局部同化碳酸盐围岩所形成的一种富含钙质成分的次生岩浆就位于碎屑岩与碳酸盐岩之间的构造薄弱带冷凝固结而成,矽卡岩型矿化与深部斑岩型矿化具有共同的成矿物质和成矿流体来源。
The Hongshan copper deposit, located in the Zhongdian arc at the southern end of the Lishun Island arc in the Sanjiang area, is a medium-sized skarn deposit formed during the subduction of the Garzê-Litang basin in the late Triassic. Generally, the skarn bodies are copper ore bodies or copper mineralized bodies, and are mainly in the form of lamellar, stratiform, veinlike and lenticular bodies that are produced in the contact zone between marble and hornfels or locally in hornfels, In direct contact with intrusive rocks. Through the study on the stable isotopic characteristics of typical minerals such as garnet, magnetite, pyrrhotite, pyrite, chalcopyrite and calcite formed in different mineralization stages and marble, it is found that the most important component of skarn The δ ~ (18) O SMOW of the mineral garnet ranged from 6.2 to 8.3 ‰, which reflected that the skarn may directly inherit the oxygen isotopic composition of the buried porphyry. The δ ~ (18) O SMOW of the magnetite mineralization phase is 13.1 ~ 14.7 ‰ (400 ℃) or 12.5 ~ 14.1 ‰ (ρ) according to the oxygen isotopic composition of magnetite (5.5-7.1 ‰) 500 ℃), suggesting that δ ~ (18) enriched CO 2 dissolved into the ore-forming fluid. The δ ~ (34) S CDT of sulfide ranged from 4.45 to 6.20 ‰, indicating that the deposit has a highly uniform sulfur source and the sulfur isotope fractionation in the fluid is very weak during the precipitation of sulfide. It can be inferred that δ 34 S ΣS of the ore-forming fluid in the main mineralization period is 5.6 ± 0.6 ‰. The δ 13 C (PDB) of the marble in the deposit is 2.0-2.2 ‰ and the δ 18 O SMOW is 24.0-24.8 ‰, which indicates that marble is recrystallized from marine carbonates Effect The δ ~ (13) C PDB range of calcite veins formed in the late stage of metallogenesis was -2.4 ~ 1.7 ‰, while the δ ~ (18) O SMOW range was 16.3 ~ 22.4 ‰, indicating that C and O originated mainly from Marble. In summary, we hypothesized that Hongshan skarn is likely to be mainly composed of a secondary calcareous component of locally calcified carbonate rocks formed by the local assimilation of carbonate rocks during the shallow emplacement of the intermediate-acid magma, The tectonic weakness between acidites is formed by condensation and solidification. Skarn mineralization and deep porphyry mineralization have common source of ore-forming materials and ore-forming fluids.