新疆北部青河县阿斯喀尔特铍矿区花岗质岩石年代学及地球化学特征

发布时间：2018-03-26 07:45

本文选题：地球化学　切入点：LA-ICP-MS锆石U-Pb定年　出处：《矿床地质》2017年03期

【摘要】：新疆北部青河县阿斯喀尔特铍矿床的形成与岩浆活动密切相关,是中国花岗岩型铍矿床的典型代表。对矿区斑状二云母二长花岗岩进行LA-ICP-MS锆石U-Pb年龄测试,获得其加权平均年龄为(216.7±2.8)Ma(MSWD=0.48),表明该岩体形成时代为晚三叠世,据此限定阿斯喀尔特铍矿床成矿时代略晚于216 Ma,为晚三叠世—早侏罗世。岩石具有高硅(w(Si O2)=70.86%~76.34%)、富碱(ALK=5.54~9.30)、富铝(w(Al_2O_3)=13.00%~14.74%,A/CNK=0.99~1.23)、低钛(w(Ti O2)=0.02%~0.18%)和镁(w(Mg O)=0.02%~1.21%)特征,为过铝质中钾-高钾岩石系列。稀土元素配分型式显示LREE的相对弱富集,HREE较平坦以及Eu弱-中等的负异常(δEu=0.37~0.90),呈略右倾型。微量元素Ba、Sr、Hf、Ti等具负异常,Rb、Th、K、Nb、Ta、La、Ce、Nd、Sm等具正异常,Rb/Sr比值较高(9.34~26.81),显示出S型花岗岩特征。结合区域资料,认为阿斯喀尔特铍矿矿区印支期花岗岩形成于后造山构造阶段,可能是上地壳含砂泥质岩石部分熔融的产物。
[Abstract]:The formation of Ascalt beryllium deposit in Qinghe County, northern Xinjiang, is closely related to magmatic activity and is a typical representative of granitic beryllium deposits in China. The LA-ICP-MS zircon U-Pb dating test for porphyry dimica monzomorphic granites is carried out in this paper. The weighted mean age is 216.7 卤2.8 Ma-MSWDU 0.48, which indicates that the formation of the rock mass is of late Triassic. The ore forming age of Ascalte beryllium deposit is a little later than 216 Ma, which is the late Triassic to early Jurassic. The rocks have the characteristics of high silicon, high silicon, high silicon, high silicon, high silicon, high silicon, high silicon, high silicon, high silicon, high silicon, alkali-rich alkali-rich alkali-rich ALK, Al2O-rich Al2O-like structure, 313.0014.744.74A / CNK 0.990.23m, 0.18mg), 0.18mg) and mg / WOO _ (0.02o) 0.021.21mg), and the main features are as follows: (1) the ore-forming age of Ascalte beryllium deposit is a little later than 216 Ma. The REE distribution pattern of LREE shows that the relative weak enrichment of HREE and the weak to moderate negative anomaly of EU (未 EU ~ (0.37) ~ (0.90)) are slightly rightward. The trace elements BabThK, NbTK, LaCeNdSm and so on have positive anomalies, such as RbThK. The high ratio of 9.34 ~ 26.81% shows the characteristics of S-type granite. It is considered that the Indosinian granites in Ascalt beryllium ore area were formed in the post-orogenic stage and may be the product of partial melting of sandy muddy rocks in the upper crust.
【作者单位】：陕西省地质调查中心;新疆地质矿产勘查开发局第七地质大队;太原理工大学矿业工程学院;
【基金】：中国地质调查局区域地质调查项目(编号:1212011120503;1212011120509;DD20160006)资助
【分类号】：P618.72

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