赵江林, 曾忠诚, 贺宁强, 杜彪, 王星, 袁璋. 新疆大红柳滩地区奇台达坂北侧新近系泉水沟组火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义[J]. 地质通报, 2017, 36(7): 1129-1146.
    引用本文: 赵江林, 曾忠诚, 贺宁强, 杜彪, 王星, 袁璋. 新疆大红柳滩地区奇台达坂北侧新近系泉水沟组火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义[J]. 地质通报, 2017, 36(7): 1129-1146.
    ZHAO Jianglin, ZENG Zhongcheng, HE Ningqiang, DU Biao, WANG Xing, YUAN Zhang. LA-ICP-MS zircon U-Pb ages, geochemical characteristics and geo-logical significance of the Neogene Quanshuigou Formation volcanic rocks in the north of Dahongliutan-Qitaidaban area, Xinjiang[J]. Geological Bulletin of China, 2017, 36(7): 1129-1146.
    Citation: ZHAO Jianglin, ZENG Zhongcheng, HE Ningqiang, DU Biao, WANG Xing, YUAN Zhang. LA-ICP-MS zircon U-Pb ages, geochemical characteristics and geo-logical significance of the Neogene Quanshuigou Formation volcanic rocks in the north of Dahongliutan-Qitaidaban area, Xinjiang[J]. Geological Bulletin of China, 2017, 36(7): 1129-1146.

    新疆大红柳滩地区奇台达坂北侧新近系泉水沟组火山岩LA-ICP-MS锆石U-Pb年龄、地球化学特征及其地质意义

    LA-ICP-MS zircon U-Pb ages, geochemical characteristics and geo-logical significance of the Neogene Quanshuigou Formation volcanic rocks in the north of Dahongliutan-Qitaidaban area, Xinjiang

    • 摘要: 出露于大红柳滩地区奇台达坂北侧的泉水沟组火山岩主要岩性为辉石安山岩、辉石安粗岩和黑云母粗面岩。用LAICP-MS技术测得黑云母安粗岩锆石U-Pb年龄为3.71±0.05Ma,形成时代为上新世。地球化学结果显示,岩石具高Al2O3(13.56%~14.32%)、高K2O(4.46%~5.79%)、高Na2O(3.68%~4.40%),低TiO2(1.09%~1.48%)、低MgO(2.64%~5.18%)的特征,属于钾玄岩序列。稀土元素总量为550×10-6~612×10-6,轻稀土元素总量较高且明显富集,重稀土元素相对亏损,具有右倾型特征和弱Eu异常(δEu=0.55~0.63)。微量元素中大离子亲石元素(K、Rb、Ba、Th、U、Pb)强烈富集,高场强元素(Ti、Nb、Ta、P)亏损,具有造山成因钾玄岩的典型特征。研究表明,泉水沟组火山岩来源于有上地壳卷入的部分熔融富集地幔区。结合区域特征,认为泉水沟组火山岩的形成与上新世喀喇昆仑-甜水海造山带沿大红柳滩-泉水沟断裂和甜水海-郭扎错断裂向NNW方向逆冲推覆有关。

       

      Abstract: The Quanshuigou Formation volcanic rocks are located in northern Dahongliutan-Qitadaban area, western Kunlun Mountains, Xinjiang. The volcanic rocks are mainly composed of pyroxene andesite, pyroxene latite, and biotite trachyte. LA-ICPMS zircon dating indicates that the volcanic rocks were emplaced at 3.71 ±0.05Ma, suggesting that the crystallization age of the Quanshuigou Formation volcanic rocks is Neogene Pliocene. Geochemical analysis shows that major elements are characterized by high Al2O3 (13.56%~14.32%) and K2O (4.46%~5.79%), but low Na2O (3.68%~4.40%), TiO2 (1.09%~1.48%) and MgO (2.64%~5.18%), thus belonging to shoshonite series. In addition, they are enriched in total REE (550×10-6~612×10-6), and the samples are enriched in LREE (light rare earth elements) and depleted in HREE (heavy rare earth elements) with weak Eu anomalies (δEu=0.55~0.63). The chondrite-normalized REE patterns show rightly-inclined type, and the olcanic rocks have rich LILE(such as K, Rb, Ba, Th, U and Pb)but poor high field strength elements (such as Ti, Nb, Ta, and P). They have typical characteristics of orogenic potassic volcanic rocks.Studies show that the rocks were formed by the partial melting enriched mantle sources mixed with a small amount of materials of the upper crust. Combined with the data of regional geology, the authors hold that the formation of the orogenic belt was related to NNW-striking thrust nappe of Karakoram-Tianshuihai along Dahongliutan-Quanshuigou fault and TianshuihaiGuozhacuo fault in the Pliocene. At that time, the volcanic rocks were formed.

       

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