| 吉林延边小西南岔铜（金）矿床早白垩世中—酸性岩浆岩年代学、地球化学及其成因探讨 |
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| 引用本文： | 王琳琳,霍 亮,王 莹.吉林延边小西南岔铜（金）矿床早白垩世中—酸性岩浆岩年代学、地球化学及其成因探讨[J].吉林大学学报(地球科学版),2022,52(5):1658-1674. |
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| 作者姓名： | 王琳琳 霍 亮 王 莹 |
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| 作者单位： | 吉林大学地球科学学院，长春130061 |
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| 摘 要： | 小西南岔铜（金）矿床位于吉林省延边地区东部，通过对小西南岔铜（金）矿床早白垩世中—酸性岩浆岩进行野外地质、岩相学、年代学和地球化学等方面的研究，进一步探讨延边乃至东北地区中生代大地构造演化。年代学研究结果表明：其同位素年龄分别为(101.69±0.61) Ma（石英闪长岩）、(101.14±0.58) Ma（英云闪长岩）、(100.82±0.62) Ma（花岗闪长岩）和(100.20±1.10) Ma（闪长玢岩），岩浆作用发生在早白垩世末期（102~100 Ma），是同一构造演化过程的产物。岩石地球化学研究表明，闪长玢岩具有典型埃达克质岩石的地球化学特征，其w(SiO2)=61.419%~62.153%，w(Al2O3)=16.872%~17.329%，w(MgO)=2.339%~2.643%，w(Na2O)=5.749%~6.623%，w(K2O)=1.483%~1.786%，w(Sr)=(691~888)×10-6，w(Yb)=(0.71~0.83)×10-6，Sr/Y值为87.4~120.0，LREE富集，说明闪长玢岩是由俯冲的大洋板片部分熔融产生的埃达克质岩浆上侵就位形成。埃达克质岩浆上侵过程中与下地壳重熔产生的酸性岩浆混合，形成的富集地幔源岩浆上侵就位形成石英闪长岩、英云闪长岩和花岗闪长岩等钙碱性花岗质杂岩；岩浆热液沿区域断裂上升过程中与大气降水混合，萃取围岩中的成矿物质，形成富铜（金）组分的成矿热液，在合适的部位卸载沉淀形成脉状铜（金）矿化。晚中生代延边地区位于古太平洋板块向欧亚大陆板块俯冲的大陆边缘环境，古太平洋板块的俯冲是形成早白垩世石英闪长岩、英云闪长岩、花岗闪长岩和闪长玢岩（脉）以及小西南岔矿床热液脉型铜（金）矿化的直接动力来源。
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| 关 键 词： | 吉林延边小西南岔铜（金）矿床 早白垩世 中—酸性岩浆岩 年代学 地球化学 构造演化 |
| 收稿时间： | 2022-03-20 |
Geochronology,Geochemistry and Genesis of Early Cretaceous Intermediate-Acidic Magmatic Rocks
in Xiaoxinancha Copper (Gold) Deposit,Yanbian Area,Jilin Province |
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| Wang Linlin,Huo Liang,Wang Ying.Geochronology,Geochemistry and Genesis of Early Cretaceous Intermediate-Acidic Magmatic Rocks
in Xiaoxinancha Copper (Gold) Deposit,Yanbian Area,Jilin Province[J].Journal of Jilin Unviersity:Earth Science Edition,2022,52(5):1658-1674. |
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| Authors: | Wang Linlin Huo Liang Wang Ying |
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| Institution: | College
of Earth Science, Jilin University, Changchun 130061, China |
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| Abstract: | Based on the comprehensive research on field geology,
petrography, geochronology and geochemistry of the Early Cretaceous
intermediate-acidic magmatic rocks of Xiaoxinancha copper (gold) deposit in
Yanbian, Jilin Province, the isotopic ages are determined to be(101.69±0.61) Ma (quartz diorite), (101.14±0.58) Ma (tonalite), (100.82±0.62) Ma (granodiorite) and (100.20±1.10) Ma (diorite porphyrite). The magmatism occurred
at the end of the Early Cretaceous (102-100 Ma), which is the product of the
same tectonic evolution process. The diorite porphyrite has the geochemical
characteristics of typical adakitic rocks, with w(SiO2)=61.419%-62.153%， w(Al2O3)=16.872%-17.329%,w(MgO)=2.339%-2.643%,w(Na2O)=5.749%-6.623%, w(K2O))=1.483%-1.786%, w(Sr)=(691-888)×10-6,w(Yb)=(0.71-0.83)×10-6,Sr/Y=87.4-120.0.The enrichment of LREE
is formed by the in-situ intrusion of adakitic magma generated by partial
melting of the subducted oceanic slab. The adakitic magma mixed with the acidic
magma produced by the remelting of the lower crust during the upwelling process
to form the enriched mantle source magma which was upwardly emplaced, and
formed the calc-alkaline granitic complexes such as quartz diorite, tonalite
and granodiorite. The magmatic hydrothermal fluid is mixed with atmospheric
precipitation during the ascent along the regional faults, extracted the
metallogenic materials in the surrounding rocks, and formed the metallogenic
hydrothermal fluid rich in copper (gold) components, and unloaded and
precipitated at a suitable location to form vein-type copper (gold)
mineralization. Yanbian area was located in the continental margin environment
where the paleo Pacific plate subducted to the Eurasian plate in the Late
Mesozoic. The subduction of the paleo-Pacific plate was the direct driving
force for the formation of Early Cretaceous quartz diorite, tonalite, granodiorite,
diorite porphyrite (dikes)and hydrothermal vein-type copper (gold)
mineralization in Xiaoxinancha deposit. |
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| Keywords: | Xiaoxinancha copper (gold) deposit in Yanbian area Jilin Province Early Cretaceous intermediate-acidic magmatic rocks geochronology geochemistry tectonic evolution |
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