鲁西金岭岩浆侵入杂岩体中角闪石岩包体成因研究  

Petrogenesis of Hornblendite Enclaves in Jinling Magmatic Complex of Intrusions from the Western Shandong Province

作　　者：胡雅璐 刘树文[1] 金子梁[2] 谢秋红 温冰冰 李子羲 HU Yalu;LIU Shuwen;JIN Ziliang;XIE Qiuhong;WEN Bingbing;LI Zixi(The Key Laboratory of Orogenic Belt and Crustal Evolution(MOE),School of Earth and Space Sciences,Peking University,Beijing 100871;School of Geosciences and Resources,China University of Geosciences(Beijing),Beijing 100083)

机构地区：[1]造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《北京大学学报（自然科学版）》2018年第2期385-397,共13页Acta Scientiarum Naturalium Universitatis Pekinensis

基　　金：国家重点基础研究发展计划(2012CB416806)和国家自然科学基金(41530207,41772188)资助

摘　　要：为了确定鲁西金岭岩浆侵入杂岩体中的角闪石岩包体成因,对该类包体进行岩相学、矿物化学和地球化学分析。结果表明,角闪石岩包体具有明显的堆晶结构,主要由角闪石和少量斜长石组成。其中,角闪石可以分为两类:一类为韭闪石,具有较低的Si O2含量和较高的Al2O3含量,是原生角闪石;另一类为阳起石、镁角闪石和浅闪石,相对富集Si O2,贫Al2O3,可能为原生角闪石晚期被改造的产物。利用角闪石全铝地质压力计对原生角闪石进行压力计算,获得其平均结晶压力为0.48 GPa。这些角闪石岩包体的微量元素特征与寄主岩石黑云母闪长岩相似,均富集轻稀土元素,亏损重稀土元素。结合原生角闪石的形成条件,可以认为这些角闪石岩包体可能与寄主岩石同源,是中地壳岩浆房闪长质岩浆分离结晶的产物。In order to determine the genesis of the hornblendite enclaves in the Jinling magmatic complex of intrusions in the Western Shandong Province,petrological,mineralogical and geochemical analyses have been conducted on the hornblendites from the complex.The hornblendites show clearly cumulus structure and are composed of plagioclases and amphiboles.The amphiboles in hornblendite enclaves can be divided into two types.The first type of amphibole shows lower SiO2 but higher Al2O3 contents and is classified as the pargasite with magmatic genesis.The other type of amphibole is composed of actinolite,magnesiohornblende and edenite with higher SiO2 but lower Al2O3,which may be attributed to modifications of the magmatic amphiboles during later tectonothermal events.The crystallization pressure of hornblendite enclaves is estimated to be 0.48 GPa using the hornblende Al2O3 geobarometer.The hornblendite enclaves show similar characters of the REE and trace elements to those of the hosting dioritic rocks,and are characterized by the LREE enrichment but HREE depletion.Together with the mineral crystalline condition of the magmatic hornblende,it is concluded that the hornblendite enclaves and their hosting diorites in the Jinling magmatic complex of intrusions may be produced by fractionation crystallization of cogenetic magmatic evolution,and the hornblendite enclaves crystalized from a lower magmatic chamber in the middle-crust level.

关 键 词：金岭岩浆侵入杂岩体 角闪石岩包体 角闪石结晶压力 岩浆成因 鲁西地区 

分 类 号：P611[天文地球—矿床学]