| 徐九华,何知礼,申世亮,杨振林,杜加锋.小秦岭文峪-东闯金矿床稳定同位素地球化学及矿液矿质来源[J].地质找矿论丛,1993,(2):87-100 |
| 小秦岭文峪-东闯金矿床稳定同位素地球化学及矿液矿质来源 |
| STABLE ISOTOPE GEOLOGY OF THE DONGCHUANG AND THE WENYU GOLD DEPOSITS AND THE SOURCE OF ORE-FORMING FLUID AND MATERIALS |
| 投稿时间：1992-03-02 |
| DOI：10.6053/j.issn.1001-1412.1993.2. 010 |
| 中文关键词: 小秦岭金矿 稳定同位素 成矿流体矿质来源 |
| 英文关键词: |
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| 中文摘要: |
| 文峪、东闯金矿是著名的小秦岭金矿带内毗邻的两个石英脉型金矿床.本文研究了氢、氧、碳、硫和铅同位素地质特征,结果表明成矿流体兼有岩浆水和变质水特点,并叠加了大气降水,硫、铅和金等成矿物质具深源特点,来自太华群基底的深熔过程. |
| 英文摘要: |
| Located in the middle of the Xiaoqinling Mt. area, tthe Dongchuang and the Wenyu are important neighbour gold deposits. The gold-bearing quartz veins in both deposits, controlled by EW strike duc- tile shear zones, occur in the Lujiayu formation of the Archean Taihua group which has an U-Pb isotopic age of 2,200-3,400 m.y.. The late Yanshanlan granitic intrusion, named wenyu, is situated in the north. The major metallic minerals in the ore are native gold, electrum, pyrite, galena, chalcopyrite and sphalerite, and gangue minerals mainly quartz, secondarily sericite, ankerite and calcite. Principal alteration patterns in both deposits are sericitization, silieification, pyritization, carbonotization, epidotization and chlorittization. Meassured δD values of fluid inclusions in quartz from the ore veins range from -33.8 to -87.4 per mil. And the δ18OH2O values calculated from δ18 quartz and depositional temperatures of ore, vary from 0.60 to 8.20 per mil. These show that the water inhydrothermal fluid precipitating the ore bodies could have been mainly magmatic water and metamorphic water, but local meteoric water might take part in the late mineralization. The values of δ13O from carbonates in the ore vary from -7.51 to -3.19 per mil, indicating that carbon was derived from magmatic or anatectic source. The values of δ13C of CO2 in fluid inclusions from vein quartz change considerably from 27.26 to 4.42 per mil, suggesting that carbon from metamorphic or other source has been mixed during mineralization.The δ34S values of sulfide samples from gold deposits range from -1.9 to +7.1 per mil, and the values of calculated δ34SH2S are from -0.43 to +6.66 per mil. Based on estimated fo2 and PH, the δ34S∑S in ore-forming fluid are less than 3.2～7.1 per mil for mineralization stage I, and less than 3.2～6.7 per mil for stage II. while for stage III, they range from -5.43 to +6.6 per mil. Combined with the δ34S values of the Archean metamorphic rocks and the wenyu intrusion, it can be concluded that sulfur in ore-forming fluid was anatectic origin, and it was relevant to anatexis of the Arehean Taihua group.The ratio of lead isotope from the wenyu and the Dongchuang gold deposits, ranging from 17.06 to 17.305 (206Pb/204Pb), 15.425 to 15.739 (207Pb/204Pb), and 37.557 to 38.450 (208Pb/204Pb), are identical with those of other gold deposits in the Xiaoqinling. These values show that the lead of both deposits was derived from lower crust or a mantle source. Mathematic geological study has demonstrated that gold in altered rocks has a close relationship with lead, silver and copper, suggesting that gold and other ore-forming materials were also originated from the Archean Taihua group in the lower crust during migmatization and granitization. |
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