冈底斯西段朱诺斑岩铜矿床岩浆氧逸度和含水性

发布时间：2018-05-07 13:36

本文选题：氧逸度 + 含水性　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：岩浆氧逸度和水含量对于斑岩铜矿的形成至关重要,朱诺斑岩铜矿床为冈底斯西段一典型的形成于后碰撞环境的斑岩型铜矿。矿区岩浆作用发育,主要包括成矿前约50Ma石英斑岩,成矿期13~15Ma二长花岗斑岩、斑状二长花岗岩及其中的包体等,成矿晚期10~12Ma花岗斑岩。本文通过锆石、角闪石、黑云母、斜长石、磁铁矿-钛铁矿、黑云母等方法研究朱诺各阶段岩浆的氧逸度和含水性,并与冈底斯东段的矿床进行区域对比。朱诺成矿期包体锆石Ce~(4+)/Ce~(3+)比值为372~919,据角闪石成分的ΔFMQ为+1.2~+3.0,水含量为4.0~4.3 wt%,据斜长石成分的水含量为3.5~4.2 wt%;二长花岗斑岩锆石Ce~(4+)/Ce~(3+)比值为142~364,据角闪石成分的ΔFMQ为+2.6~+3.4,水含量为3.2~3.9 wt%,据斜长石成分的水含量为2.7~3.4 wt%;斑状二长花岗岩锆石Ce~(4+)/Ce~(3+)比值为45~182,据角闪石成分的ΔFMQ为+2.8~+3.7,水含量为2.9~3.7 wt%,据斜长石成分的水含量为2.9~3.1 wt%;闪长玢岩锆石Ce~(4+)/Ce~(3+)比值为3~195,ΔFMQ为+2.7~+3.3。二长花岗斑岩和包体的氧逸度、水含量明显高于斑状二长花岗岩、闪长玢岩,因此,包体或者含包体的斑状二长花岗岩及二长花岗斑岩与成矿的关系最为密切。朱诺成矿前石英斑岩锆石Ce~(4+)/Ce~(3+)比值为328~959,水含量小于2.8wt%,较成矿期的岩石具有高氧逸度低含水性的特征。成矿后花岗斑岩锆石Ce~(4+)/Ce~(3+)比值为39~196,水含量小于3.0wt%,较成矿期岩石具有低氧逸度和低含水性的特征。本文对冈底斯东西段矿床氧逸度和含水性的对比发现,拉抗俄成矿岩体Ce~(4+)/Ce~(3+)比值为492.25,达布成矿岩体Ce~(4+)/Ce~(3+)比值为398.37,冲江成矿岩体Ce~(4+)/Ce~(3+)比值为263.83,朱诺成矿岩体Ce~(4+)/Ce~(3+)比值为249.24;驱龙成矿斑岩、甲玛成矿岩体的(Ce/Nd)/Y的比值大于0.01,1000(Eu/Eu*)/Y比值大于1,Eu/Eu*比值大于0.4;朱诺的成矿岩体的锆石(Ce/Nd)/Y比值小于0.01,1000(Eu/Eu*)/Y比值小于1,Eu/Eu*比值小于0.4。朱诺斑岩铜矿床较东段的斑岩铜矿床具有更低的岩浆氧逸度和含水性,暗示冈底斯西段受到更多印度陆壳物质的混染。
[Abstract]:The oxygen fugacity and water content of magma are very important for the formation of porphyry copper deposits. The Juno porphyry copper deposit is a typical porphyry copper deposit formed in the post-collision environment in the west section of Gangdis. Magmatism developed in the ore area, including 50Ma quartz porphyry before mineralization, 13~15Ma Erchanggranitic porphyry during metallogenic period, porphyry monzogranite and its middle inclusions, and 10~12Ma granitic porphyry in late metallogenic period. In this paper, oxygen fugacity and water content of magma at different stages of Juno are studied by means of zircon, hornblende, biotite, plagioclase, magnetite, ilmenite and biotite. In Juno metallogenic period, the ratio of zircon Ce~(4 ~ / ce ~ (3) is 372 ~ 919, according to hornblende composition 螖 FMQ is 1.2-3.0, water content is 4.0 ~ 4.3 wts, according to plagioclase composition, water content is 3.5 ~ 4.2wt.The ratio of Ce~(4 / Ce~(4 / Ce~(4 ~ (3) is 142 ~ 364, according to amphibole composition 螖 FMQ. The water content is 2.6-3.4 wt.The water content of plagioclase is 2.73.4wt.The ratio of zircon Ce~(4 / cefin 3 of porphyritic monzomorphic granite is 450.182, the 螖 FMQ of amphibole is 2.83.7w ~ 3.7w ~ (th), and the water content of plagioclase is 2.93.1wtt. the water content of the plagioclase is 2.93.1wtt, according to the plagioclase composition, the content of water is 2.93.7wtt, and the content of water is 2.93.7wtt, according to the composition of plagioclase. The ratios of zircon Ce~(4 ~ / ce ~ (3) and 螖 FMQ of diorite porphyrite are 31995 and 2.7 ~ 3.3 respectively. The oxygen fugacity and water content of Erchang granitic porphyry and xenoliths are obviously higher than that of porphyry granite and diorite-porphyrite. The ratio of zircon Ce~(4 ~ + / ce ~ (3) ~ (3) of quartz porphyry before Juno mineralization is 328959, and the water content is less than 2.8 wt. the ore-forming rocks have the characteristics of high oxygen fugacity and low water content. The ratio of zircon Ce~(4 ~ + / ce ~ (3) is 39 ~ (196), the water content is less than 3.0 wt, and the ore-forming period is characterized by low oxygen fugacity and low water content in the granitic porphyry, which is characterized by low oxygen fugacity and low water content. In this paper, the comparison of oxygen fugacity and water content in the east and west section of Gangdis ore deposit has been found. The ratio of Ce~(4 ~ / ce ~ (3) is 492.25, that of Dabu ore-forming body is 398.37, that of Chongjiang ore-forming body is 263.83, that of Juno ore-forming body is 249.24, that of Chongjiang ore-forming body is 263.83, that of Dabu ore-forming body is 398.37, that of Chongjiang ore-forming rock body is 263.83, and that of Juno ore-forming body is 249.24. The ratio of ce / NdU / Y of Jiama ore-forming rock body is greater than 0.01U / EU / EU / Y ratio > 1 / 10 EU / EU / Y ratio > 0.4, and the zircon ce / NdU / Y ratio of Juneau ore-forming rock mass is less than 0.01 / 1000 / EU / U / Y ratio < 1 EU / EU * / Y ratio < 0.4 EU / EU * / Y ratio, and the zircon / ce / NdU / Y ratio of Juneau ore-forming rock mass is less than 0.01U / NdU / Y ratio. The Juno porphyry copper deposit has lower magmatic oxygen fugacity and water bearing than the porphyry copper deposit in the eastern part, suggesting that the western Gangdis section is contaminated by more Indian continental crust materials.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.41

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