桂东大瑶山地区加里东期基性岩的发现及地质意义
发布时间：2018-08-27 06:32
【摘要】：思泰岩体位于扬子地块与华夏地块拼合带的西南段,对剖析华南区域构造演化具有重要的地质意义。思泰岩体主要由辉长岩、辉长闪长岩组成。LA-ICP-MS锆石U-Pb年代学分析表明,辉长岩的侵位结晶时限为(445±1)Ma,属于加里东期岩浆活动产物。岩石具有高钾钙碱性特征;其铝饱和指数为0.95~1.99,属准铝质-过铝质岩石;岩石具有中等偏高的Mg#值(0.43~0.51)。锆石的εHf(t)值主要集中在0.39~5.84之间,其一阶段模式年龄为1 181~855 Ma,暗示其源区主要为中-新元古代岩石圈地幔。综合地球化学、锆石Hf同位素组成特征及区域地质资料,认为思泰岩体是在陆内碰撞造山期后伴随岩石圈局部伸展-减薄,软流圈高温地幔物质上涌,从而导致中-新元古代岩石圈地幔物质的部分熔融,随后岩浆发生上升侵位固结成岩,在上升侵位的过程中受到少量的地壳物质的混染而形成。
[Abstract]:The Sitai rock body is located in the southwest section of the Yangtze and Huaxia blocks, which is of great geological significance to the analysis of the regional tectonic evolution in South China. The dating analysis of zircon U-Pb shows that the emplacement crystallization time of gabbro is (445 卤1) Ma, which is the product of Caledonian magmatic activity. The rock has the characteristics of high potassium calc-alkalinity, and its aluminum saturation index is 0.95 ~ 1.99, which belongs to the quasi-aluminum-peraluminous rock, and the rock has a moderate high Mg# value (0.43 ~ 0.51). The 蔚 Hf (t) value of zircon is mainly between 0.39 and 5.84, and its model age of 1 181 ~ 855 Ma, indicates that the source region of zircon is mainly Mesoproterozoic lithospheric mantle. Based on geochemistry, zircon Hf isotopic composition and regional geological data, it is considered that the Sitai rock mass is associated with the local extension and thinning of lithosphere after the intracontinental collision orogeny and the upwelling of the asthenospheric high temperature mantle material. This resulted in partial melting of the Mesoproterozoic lithospheric mantle material and subsequent magmatic emplacement consolidation diagenesis, which was formed by the mixing of a small amount of crustal materials during the ascending emplacement process.
【作者单位】： 广西壮族自治区地质调查院;中化地质矿山总局广西地质勘查院;
【基金】：中国地质调查局项目“桂东-粤西地质矿产调查”(DD20160035)
【分类号】：P588.124
[Abstract]:The Sitai rock body is located in the southwest section of the Yangtze and Huaxia blocks, which is of great geological significance to the analysis of the regional tectonic evolution in South China. The dating analysis of zircon U-Pb shows that the emplacement crystallization time of gabbro is (445 卤1) Ma, which is the product of Caledonian magmatic activity. The rock has the characteristics of high potassium calc-alkalinity, and its aluminum saturation index is 0.95 ~ 1.99, which belongs to the quasi-aluminum-peraluminous rock, and the rock has a moderate high Mg# value (0.43 ~ 0.51). The 蔚 Hf (t) value of zircon is mainly between 0.39 and 5.84, and its model age of 1 181 ~ 855 Ma, indicates that the source region of zircon is mainly Mesoproterozoic lithospheric mantle. Based on geochemistry, zircon Hf isotopic composition and regional geological data, it is considered that the Sitai rock mass is associated with the local extension and thinning of lithosphere after the intracontinental collision orogeny and the upwelling of the asthenospheric high temperature mantle material. This resulted in partial melting of the Mesoproterozoic lithospheric mantle material and subsequent magmatic emplacement consolidation diagenesis, which was formed by the mixing of a small amount of crustal materials during the ascending emplacement process.
【作者单位】： 广西壮族自治区地质调查院;中化地质矿山总局广西地质勘查院;
【基金】：中国地质调查局项目“桂东-粤西地质矿产调查”(DD20160035)
【分类号】：P588.124
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