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为了解浙江安吉多金属矿区岩浆作用的性质及其与成矿作用的关系,对区内石英二长斑岩的地球化学和年代学展开研究。地球化学结果表明,该岩脉高硅(w(SiO2)=65.91%～66.72%)、富碱(w(K2O+Na2O)=7.82%～8.26%)、高钾(w(K2O)/w(Na2O)=1.58～1.82),铝饱和指数A/CNK=0.86～0.91,轻稀土元素和大离子亲石元素Rb、Th、K相对富集,铕弱负异常,Ba、Sr和高场强元素Nb、Ti、P相对亏损,属准铝质―钾玄岩系列。铝饱和指数及结晶分异指数显示,该岩脉属I型花岗岩系列。年代学结果表明,该岩脉锆石U-Pb年龄为(137.3±1.6)Ma,与区内杂岩体同期。据野外证据,该岩脉的侵位时代指示北东向湖州―学川大断裂在(137.3±1.6)Ma左右再次活动,且该时间也为北西向孝丰―三门湾大断裂再度活跃的最早年龄。区内岩浆作用、成矿作用基本同期,岩体与矿化又具有密切的空间关系,表明区内成矿作用和岩浆活动密切相关。
In order to understand the nature of magmatic processes in the Anji polymetallic deposit in Zhejiang Province and its relationship with mineralization, the geochemistry and geochronology of quartz monzonite porphyry in the area are studied. The geochemical results show that the ratio of high K (w (SiO2) = 65.91% ~ 66.72%) and K (K2O + Na2O) = 7.82% ~ 8.26% Na2O) = 1.58-1.82), and the index of aluminum saturation A / CNK = 0.86-0.91. The light rare earth elements and large lithophile elements Rb, Th and K are relatively enriched, the weak negative anomalies of europium, Ba, Sr and high field strength elements Nb, Ti, P relative loss, is a quasi-aluminum - potassium basalt series. Aluminum saturation index and the crystallization index show that the vein is a type I granite series. The geochronological results show that the zircon U-Pb ages of the dikes are (137.3 ± 1.6) Ma, which coincide with the complex intrusion in the area. According to field evidence, the emplacement age of the dikes indicates that the NE-trending Huzhou-Xuechuanda fault reactivated at (137.3 ± 1.6) Ma, and this time was again active for the northwest Xiaofeng-Sanmenwan fault The earliest age. The magmatism and mineralization in the area have basically the same period, and there is a close spatial relationship between the rock mass and mineralization, indicating that the mineralization in the area is closely related to the magmatism.