东昆仑东段加鲁河中基性岩体环石英捕虏晶角闪石和黑云母矿物学特征及其对岩浆混合过程的约束

发布时间：2018-04-02 13:30

  本文选题：东昆仑造山带　切入点：加鲁河中基性岩体　出处：《地学前缘》2017年06期

【摘要】：加鲁河中基性岩体位于东昆仑造山带东段,岩体边部岩浆混合作用明显,富含暗色环边石英,是研究岩浆混合作用的理想地质体。本文在详细岩石学研究基础上,对寄主岩(香加南山花岗岩基)-包体-包体捕虏晶-暗色环边石英的矿物(黑云母和角闪石)进行电子探针成分分析。研究表明,不同类型黑云母的Fe~(2+)/(Fe~(2+)+Mg)比值基本一致,介于0.53~0.59,寄主岩黑云母的MgO含量较低(8.06%~8.29%),包体捕虏晶-暗色环边的黑云母MgO含量较高(分别为9.38%~9.45%和9.25%~9.52%);不同类型角闪石的(Ca+AlⅣ)较高,大于0.5,寄主岩角闪石具有较高的FeO~T含量(20.27%~21.01%)和较低Mg#值(45~47);包体-包体捕虏晶-暗色环边的角闪石具有较低的FeO~T含量(分别为18.31%~19.49%、18.11%~18.90%和18.01%~18.43%)和较高的Mg#值(分别为50~54、52~53和55~60)。寄主岩的角闪石(为铁浅闪石)和黑云母(为铁质黑云母)具壳型特征;包体-包体捕虏晶-暗色环边的角闪石(为镁角闪石)和包体-暗色环边的黑云母(为镁质黑云母)具壳幔型特征。寄主岩和包体捕虏晶的角闪石具有近似的成分和结晶环境,显示包体与寄主岩间存在成分交换。早期富水岩浆有利于磁铁矿和钛铁矿结晶,使晚期结晶的暗色环边矿物(黑云母和角闪石)具有较高的MgO含量和较低的FeO~T含量,以及最低的结晶温度和压力。
[Abstract]:The Jialuhe Middle basic Rock body is located in the eastern part of the East Kunlun orogenic belt. The magma mixing at the edge of the rock body is obvious and rich in dark ringed quartz, so it is an ideal geological body to study magmatic mixing. The electron probe analysis of minerals (biotite and hornblende) of host rock (Xianggananshan granite base, inclusion-xenocrystalline enclave quartz) shows that the ratios of different types of biotite are basically the same. Between 0.53 and 0.59, the content of MgO in the host rock biotite is lower than 8.06 and 8.29. The MgO content of xenocrystallite and dark ring is higher (9.38% and 9.52%, respectively), and that of different types of amphibole is higher than that of other types of hornblende. More than 0.5, the host hornblende has a higher FeO~T content (20.277.01) and a lower Mg# value (454.47%), a lower FeO~T content (18.31% 18.1118.90% and 18.01% 18.4343) and a higher Mg# value (505452% and 556060) for hornblende on the side of the xenocrystalline and dark ring. The hornblende (iron shallower amphibole) and biotite (ferric biotite) of the main rock are crustal; The hornblende (magnesium hornblende) and biotite (magnesia biotite) on the enclave enclave xenocryst and dark color ring edge are characterized by crust-mantle type. The amphibole of host rock and enclave xenocryst has similar composition and crystallization environment. The results show that there is an exchange of composition between the xenoliths and host rocks, and the early water-rich magma is favorable to the crystallization of magnetite and ilmenite, which results in a higher MgO content and a lower FeO~T content in the late crystallized dark rimmed minerals (biotite and hornblende). And the lowest crystallization temperature and pressure.
【作者单位】： 长安大学地球科学与资源学院西部矿产资源与地质工程教育部重点实验室国土资源部岩浆作用与找矿重点实验室;南阳理工学院土木工程学院;中国地质大学(北京)地球科学与资源学院;山西师范大学地理科学学院;
【基金】：国家自然科学基金项目(41472191,41502191,41172186,40972136) 中央高校基本科研业务费专项资金项目(310827161002,310827161006) 青海省国土资源厅-中国铝业公司公益性区域地质矿产调查基金项目(200801)
【分类号】：P57;P588.1
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