| 内蒙古大青山地区孔兹岩系中钙硅酸盐岩的组成和地球化学特征 |
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| 引用本文： | 徐仲元,刘正宏,胡风翔,杨振升.内蒙古大青山地区孔兹岩系中钙硅酸盐岩的组成和地球化学特征[J].吉林大学学报(地球科学版),2005,35(6):681-689. |
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| 作者姓名： | 徐仲元 刘正宏 胡风翔 杨振升 |
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| 作者单位： | 1. 吉林大学,地球科学学院,吉林,长春,130061
2. 内蒙古地质调查院,内蒙古,呼和浩特,010020 |
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| 基金项目： | 中国地质调查局地质调查项目 |
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| 摘 要： | 在内蒙古大青山地区的孔兹岩系中,透辉片麻岩岩组以钙硅酸盐岩为特征的岩石组合作为一个独立的岩石地层单元产于榴云片麻岩岩组之上、大理岩岩组之下.该岩组由透辉片麻岩(DG)和透辉长石变粒岩(DFG)、长石透辉变粒岩(FDG)、透辉石岩(DD)、透辉大理岩(DM)组成,普遍以富含透辉石、榍石、方柱石和磷灰石为特征.富Ca、Sr、Na,贫Cr、Ni、Co、Sc的特征显示该岩组中有化学沉积物的存在.并且,从DM-DD-FDG-DFG和DG表现的CaO与SiO2负相关、Al2O3与SiO2正相关反映了岩石中碎屑组分增加、化学沉积减少的趋势.常量元素、微量元素和稀土元素的分布特征说明是一套由富铁白云质泥岩-钙质泥岩、钙质杂砂岩夹泥质灰岩、泥灰岩-含钙质长石砂岩组成的沉积建造,形成于干旱气候、潮间带或泻湖、陆源碎屑供给不足的环境中.消除化学沉积的影响后,该岩组的地球化学特征尤其是稀土元素与区内的榴云片麻岩十分相似,反映它们有共同的源区.它与榴云片麻岩岩组、大理岩岩组一起构成碎屑沉积-碎屑沉积加化学沉积-化学沉积组成的沉积旋回,类似于华北克拉通内中元古代长城系的沉积特征,因而支持孔兹岩系形成于克拉通内沉积盆地的观点.
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| 关 键 词： | 孔兹岩系 钙硅酸盐岩 地球化学 大青山 内蒙古 大青山 地区 孔兹岩系 钙硅酸盐岩 组成 地球 化学特征 Area Daqingshan Khondalite Series Rocks Characteristics Mongolia 沉积盆地 华北克拉通 支持 沉积特征 长城系 中元古代 |
| 文章编号： | 1671-5888(2005)06-0681-09 |
| 收稿时间： | 2005-03-24 |
| 修稿时间： | 2005年3月24日 |
Geochemical Characteristics of the Calc-Silicate Rocks in Khondalite Series in Daqingshan Area, Inner Mongolia |
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| XU Zhong-yuan,LIU Zheng-hong,HU Feng-xiang,YANG Zhen-sheng.Geochemical Characteristics of the Calc-Silicate Rocks in Khondalite Series in Daqingshan Area, Inner Mongolia[J].Journal of Jilin Unviersity:Earth Science Edition,2005,35(6):681-689. |
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| Authors: | XU Zhong-yuan LIU Zheng-hong HU Feng-xiang YANG Zhen-sheng |
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| Institution: | 1. College of Earth Sciences, Jilin University, Changchun 130061, Chinas 2. Inner Mongolia Institute of Geological Survey, Hohhot 010020, China |
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| Abstract: | In the khondalite series in Daqingshan area,Inner Mongolia,Di gneiss association is a independent litho-stratigraphic unit characteristic of calc-silicate rocks overlying a GaBi gneiss association and being overlain by a marble association.Characterized by generally containing diopside,sphene,scapolite and apatite,the unit is composed of diopside gneisses(DG) and diopside-feldspar granulitite(DFG),feldspar-diopside granulitite(FDG),diopsidite(DD) and diopside marble(DM).The association is rich in Ca,Sr,Na and depleted in Cr,Ni,Co,Sc,suggesting the presence of chemical sediments in the unit.Moreover,the negative correlation of CaO and positive of Al_2O_3 with SiO_2 reflect an increasing abundance of clastic rocks and a decreasing trend in chemical sediments from DM via DD,FDG to DFG and DG.The characteristics of major,trace and rare earth elements suggest a protolith association of(iron-rich) dolomitic pelite,calcareous mudstone and greywacke intercalated by pelitic limestone and marlite,calcareous-bearing arkose,which was deposited in the setting of dry,intertidal or laguna with insufficient supply of the terrigenous detrital material.Their similarity to GaBi gneiss in geochemistry,especially in REE,when chemical sediments are considered separately,reflects that they probably shared a mutual provenance to GaBi gneiss.The Di gneiss association,GaBi gneiss association and marble association make up a sedimentary cycle from clastic via clastic mixed by chemical to chemical sediment,a sedimentary feature characteristic of Mid-Proteroroic Changcheng Group,hence supporting the view that the khondalte series was deposited within an intracratonic basin. |
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| Keywords: | khondalite series calc-silicate rocks geochemistry Daqingshan |
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