新疆伊吾县下马崖东山铜(金)矿床地质地球化学特征
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摘要
东山铜(金)矿位于新疆准噶尔盆地东南部,哈尔里克古生代复合岛弧带东段,带内矿床成因类型研究程度较低,南北两侧岛弧带内近年均发现较大规模斑岩型铜矿。东山铜金矿体呈脉状、网脉状产于花岗斑岩体边部花岗闪长岩节理裂隙中,矿石矿物主要有黄铜矿、黄铁矿、磁铁矿、赤铁矿等,与典型斑岩型铜矿类似。主要含矿岩体花岗闪长岩SiO_2、Al_2O_3、MgO含量分别为64.3%~68.15%,15.6%~16.6%,1.29%~1.69%。岩体Y和Yb含量低但具较高的Sr值,具埃达克岩特征;岩体大离子亲石元素Rb,Ba,U,K等元素相对富集,高场强元素Nb,Ta,Zr等相对亏损,具明显的Nb,Ta,Ti负异常特征,表明其形成于岛弧环境。埃达克岩和岛弧环境是新疆北部斑岩型铜矿的两个典型特征,本文通过矿床地质特征及含矿岩体地球化学特征研究,对比东山铜(金)矿与新疆北部斑岩型铜矿的成矿特征及构造环境,认为东山铜(金)矿的矿床成因类型应为斑岩型铜金矿床且区内具斑岩型铜矿的成矿潜力。
The Dongshan Cu(Au) deposit is located in the southeastern part of the Junggar Basin in Xinjiang, belonging to the eastern part of the Harlike Paleozoic island arc belt.The genetic type of ore deposits in the belt is relatively low, and in recent years, near by the belt many large scale porphyry copper deposits have been found. This paper is of certain significance for finding porphyry copper deposits in the belt. The orebodies are produced in the fissures of granodiorite in the striped type or in vein. The ore minerals are composed of chalcopyrite, pyrite, magnetite and hematite, is similar to typical porphyry copper deposits. The SiO_2,Al_2O_3 and MgO content of the ore-contained granite-diorite is 64.3% ~ 68.15%, 15.6% ~ 16.6% and1.29% ~ 1.69%, respectively. The granite-diorites are charactered by high Sr content and the low content of Y and Yb, meaning this rocks may be adakite. The granite-diorites are enriched in Ta, U, K and other large ion lithophile elements, lost in field strength elements Nb, Ta and Zr, and have significant Nb, Ta and Ti negative anomaly, indicating that the rocks were formed in island arc environment. The adakite and island arc environment are two typical characteristics of porphyry copper deposits in northern Xinjiang. This paper do the research of geological characteristics of the deposit and the geochemical characteristics. By comparing the metallogenic characteristics and tectonic setting of the Dongshan Cu(Au) deposit with the northern porphyry Cu deposit in the northern part of Xinjiang, we infer that this study area have the mineralization potential of the porphyry copper deposit and the Dongshan Cu(Au) is a porphyry-type Cu(Au) deposit.
The Dongshan Cu(Au) deposit is located in the southeastern part of the Junggar Basin in Xinjiang, belonging to the eastern part of the Harlike Paleozoic island arc belt.The genetic type of ore deposits in the belt is relatively low, and in recent years, near by the belt many large scale porphyry copper deposits have been found. This paper is of certain significance for finding porphyry copper deposits in the belt. The orebodies are produced in the fissures of granodiorite in the striped type or in vein. The ore minerals are composed of chalcopyrite, pyrite, magnetite and hematite, is similar to typical porphyry copper deposits. The SiO_2,Al_2O_3 and MgO content of the ore-contained granite-diorite is 64.3% ~ 68.15%, 15.6% ~ 16.6% and1.29% ~ 1.69%, respectively. The granite-diorites are charactered by high Sr content and the low content of Y and Yb, meaning this rocks may be adakite. The granite-diorites are enriched in Ta, U, K and other large ion lithophile elements, lost in field strength elements Nb, Ta and Zr, and have significant Nb, Ta and Ti negative anomaly, indicating that the rocks were formed in island arc environment. The adakite and island arc environment are two typical characteristics of porphyry copper deposits in northern Xinjiang. This paper do the research of geological characteristics of the deposit and the geochemical characteristics. By comparing the metallogenic characteristics and tectonic setting of the Dongshan Cu(Au) deposit with the northern porphyry Cu deposit in the northern part of Xinjiang, we infer that this study area have the mineralization potential of the porphyry copper deposit and the Dongshan Cu(Au) is a porphyry-type Cu(Au) deposit.
引文
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[16]芮宗瑶,黄崇轲,齐国明,等.中国斑岩铜(钼)矿床[M].北京:地质出版社,1984.
[2]赵泽南,王银宏,王建平.东天山土屋铜矿闪长玢岩地球化学、UPb年代学及其地质意义[J].矿物学报,2014(4):512-520.
[3]屈迅,徐兴旺,梁广林.蒙西斑岩型铜钼矿地质地球化学特征及其对东准噶尔琼河坝岩浆岛弧构造属性的制约[J].岩石学报,2009(4):765-776.
[4]王晓地,刘德权,唐延龄,等.伊吾县琼河坝地区斑岩铜矿床地质特征及远景评价[J].新疆地质,2006,24(4):398-404.
[5]王军,聂风军,刘勇.东准噶尔蒙西斑岩型铜钼矿床地质地球化学特征[J].中国地质,2010,(4):1151-1161.
[6]张旗,王焰,熊小林,等.埃达克岩与花岗岩:挑战与机遇[M].北京:中国大地出版社,2008.
[7]董连慧,冯京,刘德权,等.新疆成矿单元划分方案研究[J].新疆地质,2010,28(1):1-15.
[8] Peccerillo R,Taylor S R..Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contrib Mineral Petrol,1976,58:63-81.
[9] Middlemost E A K.Magmas and Magmatic Rocks[M].London:Longman,1985:1-266.
[10]许茗涵.新疆斑岩型铜矿成矿地质与地球化学特征研究[D].中国地质大学(北京),2016,97.
[11] Sun S S, McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J]. In:Saunders A D,Norry M J, eds. Magmatism in the Ocean Basins. Geological Society, London,Special Publications,1989,42:313-345.
[12] Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].Journal of Petrology,1984,25:956-983.
[13] Defant M J,Drummond M S.Derivation of some modern arc magmas by melting of young subduction lithosphere[J].Nature,1990,347:662-665.
[14] Kay R W.Aleutian magnesium andesites:melts from subducted Pacific oceanic crust[J].J.Volcanol.Geotherm.Res.,1978,4:117-132.
[15] Drummond M S,Defant M J,Kepezhinskas P K.Petrogenesis of slab-derived trondhjemite-tonalite-dacite/adakite magmas. Transactions of the Royal society of Edinburgh[J].Earth Sciences,1996,87:205-215.
[16]芮宗瑶,黄崇轲,齐国明,等.中国斑岩铜(钼)矿床[M].北京:地质出版社,1984.