發(fā)布時間：2018-11-04 10:41

【摘要】：西藏多龍礦集區(qū)是目前班公湖-怒江成礦帶內(nèi)最具潛力的找礦遠(yuǎn)景區(qū),礦集區(qū)內(nèi)已發(fā)現(xiàn)4處大型斑巖銅礦,但其成礦背景尚有爭議。通過開展成礦前的薩瑪隆閃長巖鋯石U-Pb測年、巖石化學(xué)分析,結(jié)合區(qū)域內(nèi)構(gòu)造發(fā)育序次,對系列斑巖銅礦的成礦背景進(jìn)行探討。對薩瑪隆閃長巖中進(jìn)行LA-ICP-MS鋯石U-Pb測年,獲得23顆鋯石的~(206)Pb/~(238)U年齡加權(quán)平均值為121.6±1.7Ma(MSWD=1.9),代表了閃長巖的成巖年齡。薩瑪隆閃長巖的全巖巖石化學(xué)分析結(jié)果顯示,該巖石屬于中鉀富鈉巖石,富集輕稀土元素和大離子親石元素,虧損重稀土元素和高場強元素,具有高Sr、低Y特征,相對富集Cr、Ni等不相容元素,有埃達(dá)克巖的親和性。閃長巖具相對較高的(~(87)Sr/~(86)Sr)i值和較低的(~(143)Nd/~(144)Nd)i值、ε_(Nd)(t)。全巖巖石化學(xué)特征顯示,薩瑪隆閃長巖起源于下地殼角閃巖相,可能有幔源物質(zhì)混入。礦區(qū)內(nèi)早期走滑斷層切穿薩瑪隆閃長巖,指示多龍礦集區(qū)內(nèi)主要控巖-控礦走滑斷層可能形成于116~121Ma,多龍礦集區(qū)內(nèi)系列斑巖銅礦形成于班公湖-怒江洋向北俯沖末期的構(gòu)造轉(zhuǎn)換階段。
[Abstract]:The Dulong ore concentration area in Tibet is the most potential ore prospecting area in the Bangonghu-Nujiang metallogenic belt at present. Four large porphyry copper deposits have been found in the ore concentration area, but the metallogenic background is still controversial. The metallogenic setting of a series of porphyry copper deposits is discussed by means of U-Pb dating of zircon and petrochemical analysis of the pre-metallogenic Samaronite diorite combined with the sequence of tectonic development in the region. The LA-ICP-MS zircon U-Pb dating of the Samaron diorite shows that the weighted average of ~ (206) Pb/~ (238) U age of 23 zircons is 121.6 鹵1.7Ma (MSWD=1.9), which represents the diagenetic age of the diorite. The chemical analysis of the whole rock of Samaron diorite shows that the rock belongs to medium potassium and sodium rich rock, which is rich in light rare earth elements and large ion lithophile elements, and is depleted of heavy rare earth elements and high field strength elements, and has the characteristics of high Sr, and low Y, Relative enrichment of incompatible elements, such as Cr,Ni, has the affinity of adakite. Diorite has relatively high (87) Sr/~ (86) Sr) i) and lower (~ (143) Nd/~ (144) Nd) i), 蔚 _ (Nd) (t). The petrochemical characteristics of the whole rock indicate that the Samaron diorite originated from the amphibolite facies of the lower crust and may be mixed with mantle source materials. The early strike-slip fault cut through Samaron diorite in the mining area, indicating that the main rock-controlled strike-slip fault may have been formed at 116 ~ 121Ma. A series of porphyry copper deposits were formed in the late stage of northward subduction of Bangong Lake-Nujiang Ocean.
【作者單位】： 中國地質(zhì)調(diào)查局成都地質(zhì)調(diào)查中心;西藏地質(zhì)礦產(chǎn)勘查開發(fā)局第五地質(zhì)大隊;
【基金】：國家自然科學(xué)基金項目《西藏自治區(qū)改則縣多不雜斑巖銅金礦床巖漿演化與成礦背景研究》(批準(zhǔn)號:41202049)、《西藏岡底斯過鋁花崗巖的巖石成因及其對地殼生長的約束》(編號:41272091) 中國地質(zhì)調(diào)查局項目《中國礦產(chǎn)地質(zhì)與成礦規(guī)律綜合集成和服務(wù)》(礦產(chǎn)地質(zhì)志)(編號:DD20160346)、《滇西地區(qū)三稀等重要礦產(chǎn)地質(zhì)調(diào)查》(編號:DD20179604)、《西南三江有色金屬資源基地調(diào)查》(編號:DD20160016)
【分類號】：P597.3;P618.41

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