本文選題：鋯石U-Pb年齡 + 幔源巖漿　； 參考：《地質(zhì)與勘探》2017年05期

【摘要】：東昆侖造山帶早中生代幔源巖漿底侵不僅為花崗巖類的廣泛發(fā)育提供了能量和物質(zhì)基礎(chǔ),也為厘定區(qū)域構(gòu)造環(huán)境提供了新的約束。本文對區(qū)域上發(fā)育的小尖山巖體、拉陵高里溝腦2、3號巖體開展了精確的鋯石U-Pb年代學(xué)研究,并與區(qū)域上鎂鐵質(zhì)巖體做了對比。LA-ICP-MS U-Pb定年結(jié)果表明,小尖山巖體磁黃鐵礦化輝長巖鋯石~(206)Pb/~(238)U-~(207)Pb/~(235)U諧和年齡為247.1±1.1Ma,與前人獲得的中細粒輝長巖年齡相差20Ma,暗示該巖體為多期巖漿活動的產(chǎn)物。拉陵高里溝腦2號和3號巖體輝長巖鋯石~(206)Pb/~(238)U-~(207)Pb/~(235)U諧和年齡分別為(244.9±1.6)Ma和(238.4±4.1)Ma,二者年齡在測試誤差范圍內(nèi)一致,為同期巖漿作用的產(chǎn)物。結(jié)合區(qū)域上已知鎂鐵質(zhì)巖體的形成時代及地球化學(xué)特征,認為早中生代幔源巖漿形成于后碰撞伸展環(huán)境,活動時限為251~221Ma。該期幔源巖漿與地殼物質(zhì)發(fā)生了廣泛的物質(zhì)與能量交換,是今后該區(qū)銅鎳礦勘查的重要對象之一。
[Abstract]:The early Mesozoic mantle magmatic underplating in the East Kunlun orogenic belt not only provides the energy and material basis for the extensive development of granites, but also provides a new constraint for determining the regional tectonic environment. In this paper, the zircon U-Pb dating of the Xiaojianshan and Lalinggaoligounao 2 and 3 intrusions developed in the region has been carried out, and the results of U-Pb dating show that the zircon dating results are compared with those of the magnesite bodies in the region. The zircon of pyrrhotite pyroxene in Xiaojianshan is 247.1 鹵1.1 Ma, indicating that it is the product of multi-stage magmatic activity. The harmonic age of pyrrhotite is 247.1 鹵1.1 Ma. which indicates that the pyroxene is a product of multi-stage magmatic activity. The corresponding ages of gabbro zircon of Laling Gaoligou No. 2 and No. 3 are 244.9 鹵1.6)Ma and 238.4 鹵4.1 Ma, respectively, which are the same age range of magmatism and are the products of simultaneous magmatism, and the corresponding ages are 244.9 鹵1.6)Ma and 238.4 鹵4.1 Ma, respectively. They are the products of simultaneous magmatism. Based on the known age and geochemical characteristics of the magnesite in the region, it is considered that the early Mesozoic mantle-derived magma was formed in a post-collision extensional environment with a time limit of 251 ~ 221 Ma. In this period, the mantle magma and crustal material exchange widely, which is one of the important objects for the exploration of copper-nickel deposits in this area in the future.
【作者單位】： 國土資源部巖漿作用成礦與找礦重點實驗室中國地質(zhì)調(diào)查局西安地質(zhì)調(diào)查中心;
【基金】：國土資源部公益性行業(yè)科研專項項目(201511020) 國家自然科學(xué)基金(青年)項目(41402071,41302052) 中國地質(zhì)調(diào)查局地質(zhì)礦產(chǎn)調(diào)查項目(DD20160013)聯(lián)合資助
【分類號】：P542;P597.3;P612

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