云南永平卓潘碱性杂岩体岩石学和地球化学特征及成因研究  

Petrology and geochemistry of the Zhuopan alkaline complex in Yongping,Yunnan Province: Constraints on petrogenesis and tectonic setting

作　　者：陈喜峰[1] 曾普胜[2] 张雪亭[3] 徐文荣[4] 万大幅 

机构地区：[1]中国地质调查局发展研究中心,北京100037 [2]中国地质科学院国家地质实验测试中心,北京100037 [3]中国冶金地质总局矿产资源研究院,北京100025 [4]中国冶金地质总局昆明地质勘查院,昆明650203

出　　处：《岩石学报》2015年第9期2597-2608,共12页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41072073);国家重点基础研究发展计划(2012CB416805);中国地质调查局地质调查项目(1212011220912)联合资助

摘　　要：卓潘碱性杂岩体为＂三江＂地区富碱（高钾）侵入岩的重要组成部分,位于哀牢山-金沙江缝合带的中部,侵位于兰坪盆地南部的白垩系砂岩中,主要由碱性辉长岩、辉石正长岩和霞石正长岩组成。对卓潘碱性杂岩体的岩相学、岩石学、主元素和稀土微量及同位素地球化学特征的系统研究表明,该杂岩体主量元素显示低硅、富钾、高碱（K2O＋Na2O为6.92%~13.43%）、低TiO 2（0.31%~1.20%）的特征,属钾质碱性系列岩石;杂岩体的各种岩石均富集Rb、Sr、Ba、Th等大离子亲石元素、亏损Nb、Ta、Ti等高场强元素,并具有轻稀土富集的右倾型稀土元素分布模式、具较高的87Sr/86Sr、206Pb/204Pb、207Pb/204Pb、208Pb/204Pb及较低的143Nd/144Nd等特征,表明源区具有较明显的EMⅡ型富集地幔特征,源区明显受到壳源物质的混染。卓潘岩体形成于印度-欧亚大陆后碰撞的剪切和拉张的构造环境,古扬子板片向西俯冲,诱发了经过陆壳交代混染了的岩石圈地幔的部分熔融。由于兰坪走滑拉分盆地东缘断裂拉伸强度大,岩浆起源的深度大,以及岩浆源区成分（特别是CO2含量）与其它部位不同,因此在卓潘地区形成一套与金沙江-哀牢山-红河断裂带其它新生代富碱斑岩完全不同的过碱性的岩石。Located in Yongping region in the middle area of the Jinsa River-Ailaoshan tectonic zone and emplaced in Jurassic sandstone in the northern segment of strike-slip extensional basin of Lanping,Zhuopan alkaline complex is the important part of the Sanjiang alkali-rich intrusive rocks and is composed of alkali gabbro,pyroxene syenite and nepheline syenite. The major element of the alkaline complex is characterized by rich potassium,high alkaline（ K2O ＋ Na2O = 6. 92% ~ 13. 43%） and low titanium（ TiO 2= 0. 31%~ 1. 20%）. The research showed that all samples are potassic alkaline series rocks. All samples are enriched in large ion lithophile elements（ Rb,Sr,Ba,Th）,and depleted in high field strength elements（ Nb,Ta,Ti） and exhibits LREE-enriched with rightinclined REE distribution patterns. The Sr-Nd-Pb isotopes characterized by high87 Sr /86 Sr,206Pb /204 Pb,207Pb /204 Pb and208Pb /204 Pb and low143 Nd /144 Nd and showed the source area have obvious characteristics of contamination by crustal materials and the crust-mantle transitional zone between EMⅡ enriched mantle and lower crust. The Zhuopan alkaline complex formed in shear-extensional tectonic setting post India-Eurasia collision associated with the crustal shortening and thickening,the westward subduction of Yangtze paleoplate,and the upwelling of asthenosphere mixed with the subducted Yangtze paleo-plate materials. Due to the shear-extensional in the Jinsa River-Ailaoshan fault zone,the magma rapidly erupted into the strike-slip extensional basin of Lanping with primary magma characteristics.

关 键 词：卓潘碱性杂岩体 元素和同位素地球化学 富集地幔 后碰撞 云南 

分 类 号：P588.15[天文地球—岩石学]