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甘肃文县阳山金矿为西秦岭近十年来发现的超大型卡林–类卡林型金矿床,地处扬子板块西北部碧口地体北缘。本文选取阳山矿区与矿体在空间上密切相关的花岗岩样品,进行系统的元素地球化学特征分析,结合前人的年代学和Sr-Nd-Pb同位素数据来探讨其成因。阳山花岗岩SiO_2含量为60.64%~80.77%、Al_2O_3为13.68%~23.71%,K_2O为0.74%~4.32%,A/CNK为1.34~6.02,富集Cs、U、K、Pb等元素,亏损Ba、Nb、La、Ce、Sr、Ti等元素,ΣREE=14.45×10–6~143.14×10–6,平均70.31×10–6,LREE/HREE=1.39~19.52,平均10.12,具有轻稀土富集,重稀土亏损的特征,(La/Yb)N=1.48~37.26,平均17.08,球粒陨石标准化配分模式显示弱负Eu异常(δEu=0.50~1.21,平均0.77),为过铝质钙碱性花岗岩。结合前人对花岗岩、碧口群和泥盆系三河口组的元素地球化学、年代学和Sr-Nd-Pb同位素等测试数据以及区域构造演化历史,认为阳山花岗岩来源于碰撞增厚的地壳物质——碧口群的部分熔融,在上升的过程中与泥盆系发生混染。
The Yangshan Gold Mine in Wenxian County, Gansu Province is a super-large Carlin-Carlin-type gold deposit discovered in the past ten years in the West Qinling Mountains. It is located in the northern margin of the Bikou Terrane in the northwestern part of the Yangtze Plate. In this paper, the granite samples closely related to the ore body in Yangshan mining area are selected to analyze the elemental geochemical characteristics of the ore body and to explore its origin in combination with the previous chronological and Sr-Nd-Pb isotope data. The content of SiO_2 in Yangshan granite is 60.64% ~ 80.77%, Al_2O_3 is 13.68% ~ 23.71%, K_2O is 0.74% ~ 4.32%, A / CNK is 1.34 ~ 6.02, enriching elements such as Cs, U, K and Pb, , Nb, La, Ce, Sr, Ti and other elements, with ΣREE = 14.45 × 10-6 ~ 143.14 × 10-6, an average of 70.31 × 10-6 and LREE / HREE = 1.39 ~ 19.52 with an average of 10.12. (La / Yb) N = 1.48 ~ 37.26 with an average of 17.08. The normalized distribution pattern of chondrules shows a weak Eu anomaly (δEu = 0.50 ~ 1.21, average 0.77) granite. Based on previous geochemical, geochronological, and Sr-Nd-Pb isotopic data from the granites, Bikou Group and the Devonian Sanhekou Formation and the history of regional tectonic evolution, Yangshan granite is believed to originate from the crustal thickening Material - Bikou part of the melting, in the process of rising and Devonian Department of contamination.