【摘要】：阿拉善地塊西南緣的北海子巖體由橄欖輝長巖、輝長輝綠巖、閃長巖相組成。巖體中含礦巖相為橄欖輝長巖,存在大量的硫化物珠滴,硫化物主要由磁黃鐵礦、鎳黃鐵礦與黃銅礦組成,指示巖漿深部發(fā)生過硫化物不混溶作用。巖石地球化學數(shù)據(jù)顯示北海子巖體屬于鐵質(zhì)超基性巖(m/f=2.32~5.01),富集輕稀土元素,具有明顯的Nb、Ta負異常;負εNd(t)值與高(87Sr/86Sr)i值證明巖漿源區(qū)為富集型巖石圈地幔,同位素與微量元素比值都指示巖漿在上升過程中受到了明顯的上地殼物質(zhì)混染。橄欖輝長巖中單顆粒鋯石U-Pb年齡為(374±4)Ma,結(jié)合區(qū)域地質(zhì)研究,北海子巖體可能形成于陸內(nèi)造山后伸展環(huán)境,與巖石圈地幔拆沉和對應(yīng)的軟流圈物質(zhì)上涌有關(guān),由富集型巖石圈地幔部分熔融產(chǎn)生的玄武質(zhì)巖漿侵位形成。
[Abstract]:The Beizi rock body in the southwestern margin of the Alashan block consists of olivine gabbro, pyroxenite and diorite facies. The ore-bearing rocks are olivine gabbro with a large number of sulphide droplets. The sulfides are mainly composed of pyrrhotite, nickel pyrite and chalcopyrite, indicating that sulfide immiscibility occurred in the deep part of the magma. The petrogeochemical data show that the Beihai rock body belongs to ferric ultrabasic rock (m/f=2.32~5.01), which is rich in light rare earth elements and has obvious negative Nb,Ta anomaly, negative 蔚 Nd (t) value and high (87Sr/86Sr) I value prove that the magmatic source area is enriched lithospheric mantle. The ratio of isotopes to trace elements indicates that the magma is contaminated by the upper crust material during the process of rising. The U-Pb age of single zircon in olivine gabbro is (374 鹵4) Ma, and the Beihai rock body may be formed in the post-orogenic extensional environment, which is related to the lithospheric mantle desubsidence and the corresponding asthenospheric material upwelling. Black Tortoise magma emplacement formed by partial melting of enriched lithosphere mantle.
【作者單位】： 長安大學地球科學與資源學院;西部礦產(chǎn)資源與地質(zhì)工程教育部重點實驗室;國土資源部巖漿作用成礦與找礦重點實驗室;
【基金】：國家自然科學基金項目(41672064,41372101) 國土資源部公益性行業(yè)科研專項(200911007,201011058) 長安大學科技創(chuàng)新研究項目(2013G2273009)
【分類號】：P597.3;P588.1
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本文編號：2203766