【摘要】：后碰撞階段花崗質(zhì)巖漿的源區(qū)多較為復(fù)雜,需要從多方面開展同位素的研究來加以識(shí)別,阿拉瑪斯花崗質(zhì)巖體位于西昆侖造山帶東段。先前的研究表明阿拉瑪斯巖體是后碰撞階段下地殼部分熔融。為進(jìn)一步研究阿拉瑪斯花崗巖類的源區(qū)特征,本文對(duì)阿拉瑪斯花崗巖類進(jìn)一步進(jìn)行Pb-Hf同位素的測(cè)定。結(jié)果顯示:阿拉瑪斯巖體具低的鋯石εHf(t)值為-9.5~-3.2(平均值為-5.6),二階段模式年齡為1633~2028 Ma,反映了巖漿來源于較老的下地殼部分熔融。阿拉瑪斯巖體的206Pb/204Pb范圍為18.382~19.333,平均值為18.784,207Pb/204Pb范圍為15.589~15.642,平均值為15.614,208Pb/204Pb范圍為38.585~39.080,平均值為38.800,μ值范圍為9.45~9.48,平均值為9.46,ω值的范圍33.80~38.14,平均值為36.16。在巖體源區(qū)判別圖解上,樣品主要落在上地殼的范圍內(nèi),反映了阿拉瑪斯巖體源區(qū)具有高Pb的同位素特征,說明巖漿源區(qū)有少量高Pb物質(zhì)(沉積物)的混入,從而說明后碰撞階段形成巖體的物質(zhì)來源具有多樣性。
[Abstract]:The source regions of granitic magma in post-collision stage are more complex and need to be identified by isotopic studies in many aspects. The Alamas granitic rock body is located in the eastern part of the West Kunlun orogenic belt. Previous studies have shown that the Alamas rock mass was partially melted in the lower crust during the post-collision stage. In order to further study the source characteristics of the Alamas Granitoids, the Pb-Hf isotopes of the Alamas granites have been further determined in this paper. The results show that the low zircon 蔚 Hf (t) value of Alamas is -9.5 ~ 3.2 (mean -5.6), and the two-stage model age of 1633 ~ 2028 Ma, reflects that the magma originated from the partial melting of the older lower crust. The 206Pb/204Pb range of the Alamas rock mass is 18.382 ~ 19.333, the average value is 15.589 ~ 15.642, the average value is 38.585N ~ (39.080), the average is 38.800, the 渭 value is 9.45 ~ 9.48, the average is 9.46, and the 蠅 value is 33.809 / 38.14, with an average value of 36.16. In the discriminant diagram of the source region of the rock mass, the samples mainly fall within the upper crust, which reflects the isotopic characteristics of high Pb in the source area of the Alamas rock body, indicating that there is a small amount of high Pb material (sediment) mixed in the magmatic source area. Therefore, the material sources of the rock mass formed in the post-collision stage are diverse.
【作者單位】： 中國地質(zhì)科學(xué)院;中國地質(zhì)調(diào)查局西安地質(zhì)調(diào)查中心;中國地質(zhì)科學(xué)院地質(zhì)研究所;中國地質(zhì)調(diào)查局成都礦產(chǎn)研究所;五礦勘查開發(fā)有限公司;
【基金】：中國地質(zhì)科學(xué)院中央級(jí)公益性基本業(yè)務(wù)費(fèi)專項(xiàng)基金(編號(hào):YWF201601) 中國地質(zhì)調(diào)查局國土資源大調(diào)查研究項(xiàng)目(編號(hào):DD20160004,DD20160083-1,12120115000801,121201101000150014)資助成果
【分類號(hào)】：P588.1

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本文編號(hào)：2265845