科马提岩与苦橄岩的区别及对若干晚古生代“科马提岩”的质疑  

Difference between komatiites and picrites and a discussion on some Late Paleozoic "komatiites"

作　　者：李振焕 刘学龙[1] 朱月琴 张旗[4] 罗应[1] 张昌振 陈建航 王帅帅 杨富成[1] LI Zhenhuan;LIU Xuelong;ZHU Yueqin;ZHANG Qi;LUO Ying;ZHANG Changzhen;CHEN Jianhang;WANG Shuaishuai;YANG Fucheng(College of Land and Rresources Eengineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China;Key Laboratory of Geological Information Technology,Ministry of Natural Resources,Beijing 100037,China;Development Research Center,China Geological Survey,Beijing 100037,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [2]自然资源部地质信息技术重点实验室,北京100037 [3]中国地质调查局发展研究中心,北京100037 [4]中国科学院地质与地球物理研究所,北京100029

出　　处：《地质通报》2019年第12期1971-1980,共10页Geological Bulletin of China

基　　金：中国地质调查局项目《云南省格咱铜多金属矿整装勘查区普朗斑岩型铜矿地质数据挖掘研究》(编号：KKF0201821043);《国家地质大数据汇聚与管理》(编号：DD20190381A);《资源环境重大问题综合区划与开发保护策略研究》(编号：DD20190463);国家自然科学基金项目《滇西北中甸铜厂沟燕山期斑岩型Mo-Cu矿床热液蚀变分带结构及发育机制研究》(批准号：41862009);昆明理工大学重点学科建设经费项目《地质资源与地质工程(省级一流学科)》(编号：1407839305);云南省基础研究计划项目《滇西格咱斑岩铜钼矿带多期成矿作用研究》(编号：2019FA018)

摘　　要：以往学术界更多的关注科马提岩和苦橄岩的相似性,忽略其差异。通过全数据模式,采集数据库内全球的太古宙科马提岩、后太古宙低/高钛苦橄岩数据,对比三者之间的差异发现,科马提岩更富MgO、Cr、Ni、Cs、Pb、Co和Zn,其次为低钛苦橄岩(除Co和Zn),其余主量、微量元素的含量由高至低依次为高钛苦橄岩、低钛苦橄岩、科马提岩。依据元素间的差异(如Cr/Ga、MgO/Ga、MnO/Zr、Cr/Zr等),采用密度分布函数(Density Distribution)在Matlab软件中绘制出可有效区分3类岩石的等密度判别图,并用该图对若干晚古生代"科马提岩"的岩性重新厘定。结合岩相学和地球化学特征研究表明,晚古生代"科马提岩"中,印度东部为高钛苦橄岩,越南为化学成分与科马提岩类似的低钛苦橄岩,印度拉达克地区为低钛苦橄岩。In the past,academia paid much attention to the similarity between komatiites and picrites,but ignored their differences.In this paper,the global data of Archaean komatiites and Post-Archaean low/high titanium picrites in the database were collected by full data model.Based on comparing the differences between them,the authors found that komatiites are richer in MgO,Cr,Ni,Cs,Pb,Co and Zn,followed by low-titanium picrites(except for Co and Zn).As for the other main and trace elements,high-titanium picrites has the highest content,followed by low-titanium picrites and then by komatiites.Based on the differences between elements such as Cr/Ga,MgO/Ga,MnO/Zr and Cr/Zr,the authors used density distribution to draw an isodensity discriminant map which can effectively distinguish the three types of rocks,and redefined the lithology of some Late Paleozoic"komatiites"with this diagram.The results of lithofacies and geochemical characteristics show that,in the Late Paleozoic"komatiites",the rocks in the eastern part of India are high-titanium picrites,those in Vietnam are low-titanium picrites with similar chemical composition to komatiites,and those in Ladak area of India are low-titanium picrites.

关 键 词：科马提岩 低/高钛苦橄岩 等密度判别图 晚古生代 重新厘定 

分 类 号：P588.14[天文地球—岩石学] P628[天文地球—地质学]