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元古宙岩体型斜长岩的特征及研究现状
  • ISSN号:1006-7493
  • 期刊名称:《高校地质学报》
  • 时间:0
  • 分类:P588.12[天文地球—岩石学;天文地球—地质学]
  • 作者机构:[1]中国科学院广州地球化学研究所,广州510640, [2]中国科学院研究生院,北京100039
  • 相关基金:国家自然科学基金项目(编号:40272041;40528002)资助致谢在成文过程中,承蒙周国庆教授、解广轰研究员、周金城教授和王焰博士提出宝贵意见,在此表示感谢.
中文摘要:

斜长岩是指斜长石含量〉90%的岩浆岩,可分为6类。其中,岩体型斜长岩仅赋存于前寒武纪变质地体中,形成时代主要为元古宙(2.1~0.9Ga),代表地球演化史上很重要的构造一热事件。岩体呈穹隆状或层状产出,具典型堆晶结构,有含钾长石和斜长石出溶片晶的巨晶斜长石和富铝辉石。巨晶的出溶指示了岩浆由高压至低压的变压结晶过程,体现了斜长岩体深成、浅侵位的特点。关于斜长岩的源区,之前普遍认为源于幔源玄武质岩浆,而近10年来更趋向于源区为下地壳,母岩浆的成分为纹长苏长岩和铁闪长岩等新认识;其成因模式以底侵模式和地壳舌状物熔融模式最具代表性。岩体型斜长岩时空上常与奥长环斑花岗岩共生,构成AMCG(Anorthosite—Mangerite—Charnockite—Granite)岩石组合,被认为属非造山岩浆作用的产物,可能代表大陆裂谷环境。然而,新近一些年龄结果显示,它们形成于造山作用的后期阶段,暗示岩体产出于碰撞后环境。斜长岩体中常赋存有Fe-Ti-V氧化物矿床,有的富含P及Cu,Ni硫化物等,属典型的岩浆矿床。对此,目前主要有结晶分异过程、早期堆晶过程及不混熔分离3种成因机制解释。由此对今后研究中值得关注的问题提出了一些看法。

英文摘要:

Anorthosite refers to igneous rocks consisting of over 90% plagioclase. Massif-type anorthosite is the most common type of anorthosite and with distinct characteristics. Most massif-type anorthosite bodies are Proterozoic ranging from 2.1 Gato 0.9 Ga in formation ages, representing an important tectono-thermal event in the earth evolution. The anorthosite massifs are usually dome-shaped or layered. Anorthosites often show cumulate texture composed of high-Al pyroxene and plagioclase megacrysts containing exsolution lamellaes of plagioclase and K-feldspar. The exsolution of the megacrysts indicates a polybaric crystallization process, which indicates the feature of deep generation and shallow emplacement. There exist different points of view in the petrogenesis of massif-type anorthosite. Many workers considered that the anorthosite massifs were generated from the upper mantle-derived basaltic magma. Whereas, especially in recent decade, some geologists argued that they were formed from the lower crust. The composition of the parental magma of anorthosite is considered to be more like jotunite and ferro- diorite. Two models are very common to interpret the formation of anorthosite massifs: the underplating model and the crustal tongue melting model. Most massif-type anorthosite bodies are spatially and temporally associated with rapakivi-granites, constituting an AMCG suite ( anorthosite-mangerite-charnockite-granite), as a result of anorogenic magrnatism in a continentalrift setting. However, some massifs might be formed at the late stage of orogeny, representing a post-collisional setting. Proterozoic massif-type anorthosite bodies are also hosts of P-rich Fe-Ti oxide deposits and a few of Cu-Ni sulfide deposits. These deposits are considered to be formed by fractional crystallization, primary cumulates or immiscible oxide melts.

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期刊信息
  • 《高校地质学报》
  • 中国科技核心期刊
  • 主管单位:教育部
  • 主办单位:南京大学
  • 主编:王汝成
  • 地址:南京市栖霞区仙林大道号南京大学共山楼
  • 邮编:210023
  • 邮箱:gxdzh@nju.edu.cn
  • 电话:025-83594340
  • 国际标准刊号:ISSN:1006-7493
  • 国内统一刊号:ISSN:32-1440/P
  • 邮发代号:
  • 获奖情况:
  • 1)2011年获中国高校期刊研究会颁发的“首届中国...,2)2012年“学术讨论与争鸣”栏目获江苏省科学技...,3)2012年被中国学术期刊(光盘版)电子杂志社,...,4)2013年被中国学术期刊(光盘版)电子杂志社,...,5)2014年获中国高校期刊研究会颁
  • 国内外数据库收录:
  • 美国化学文摘(网络版),美国地质文献预评数据库,日本日本科学技术振兴机构数据库,中国中国科技核心期刊,中国北大核心期刊(2004版),中国北大核心期刊(2008版),中国北大核心期刊(2011版),中国北大核心期刊(2014版)
  • 被引量:12035