ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    中亚成矿域核心区斑岩铜矿地质和地球化学特征研究现状综述

    Geological and Geochemical Characteristics of Porphyry Copper Deposits in Core Part of Central Asian Metallogenic Domain: A review

    • 摘要: 中亚成矿域核心区域发育多个斑岩型铜矿床,集中分布于哈萨克斯坦环巴尔喀什、中国新疆西准噶尔和东天山地区。笔者从成矿斑岩岩石学、地球化学、岩浆性质、矿床地质和成矿流体性质等方面,对以上地区主要斑岩铜矿的研究现状进行了总结,并概括了境内外斑岩铜矿床的异同。中亚成矿域核心区斑岩铜矿含矿斑岩主要为闪长岩、闪长玢岩、花岗闪长斑岩和石英二长岩,属钙碱性或高钾钙碱性系列,除哈萨克斯努尔卡斯甘外,大多具有埃达克岩的地球化学特征。哈萨克斯坦环巴尔喀什地区和中国西准噶尔、东天山地区斑岩铜矿成矿斑岩结晶温度主要集中在668~836℃,斑晶相结晶压力为0.8~3.2kbar(对应深度2.4~8.8km),环巴尔喀什地区成矿斑岩(ΔQFM=2.9~4.8)具有明显高于西准噶尔和东天山地区(ΔQFM=0.3~1.8)的岩浆氧逸度。中亚成矿域核心地区含矿斑岩的(87Sr/86Sr)i=0.702 5~0.706 7,εNd(t)=4.9~8.8,显示含矿岩体主要来源于新生洋壳,可能伴随古老基底物质的参与。矿区发育以钾化、绢英岩化和青磐岩化为主的热液蚀变,努尔卡斯甘矿区发育与高级泥化有关的高硫型浅成低温热液型金矿化。矿床地球化学研究显示区内斑岩铜矿硫化物的硫主要为岩浆硫(δ34S=-5‰~2‰)。环巴尔喀什地区和中国东天山土屋-延东斑岩铜矿成矿流体为氧化性的H2O-NaCl-CO2-SO2体系,西准噶尔包古图为还原性的H2O-NaCl-CO2-CH4体系。

       

      Abstract: Plenty of large and ultra-large porphyry copper deposits are occurred in the Central Asia Metallogenic Domain, which are mainly concentrated in the Balkhash of Kazakhstan and west Junggar and the eastern Tianshan of Xinjiang in China.In this paper, the research statuses of the main porphyry copper deposits in the above areas have been reviewed from the aspects of petrology, geochemistry, magmatic properties, deposit geology and ore-forming fluid properties.The similarities and differences between porphyry copper deposits in China and abroad have also been summarized.The ore-bearing porphyries are mainly diorite, diorite porphyrite, granodiorite porphyry and quartz monzonite.Most of the ore-bearing porphyries, except for Nurkazgan in Kazakhstan, have the geochemical characteristics of adakite.The crystallization temperature of ore-bearing porphyries range from 668℃ to 836℃, and the crystallization pressure of porphyry phase is 0.8~3.2kbar.The oxidation state of porphyries in the Balkhash region (ΔQFM=2.9~4.8)is significantly higher than that in the west Junggar and the eastern Tianshan area (ΔQFM=0.3~1.8).The (87Sr/86Sr)i and εNd(t)of all the ore-bearing porphyries range from 0.702 5 to 0.706 7 and from 4.9 to 8.8, respectively, indicating that the new oceanic crust is the main source of the ore rock, and a small amount of continental crustal material is also involved.The hydrothermal alteration is mainly composed of potassium alteration, sericitization and propylitization.The geochemical studies show that the sulfur of ore-forming system is mainly derived from the magma (δ34S=-5‰~2‰).The ore-forming fluid in Balkhash and Tuwu-yandong is oxidized H2O-NaCl-CO2-SO2 system, while the ones in Baogutu is a reductive H2O-NaCl-CO2-SO2 system.

       

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