鲁西彩山地区变角闪辉长岩地球化学特征及其地质意义  

Geochemistry and geological significance of the metaamphibole gabbros in Caishan area of western Shandong Province

作　　者：刘伟 靳立杰 孙天河 于松 江振国 杨帆 LIU Wei;JIN Lijie;SUN Tianhe;YU Song;JIANG Zhenguo;YANG Fan(No.1 Institute of Geology and Mineral Resources of Shandong Province,Jinan 250010,China;Shandong Engineering Laboratory for High-Grade Fe Ores Exploration and Exploitation,Jinan 250010,China)

机构地区：[1]山东省第一地质矿产勘查院,山东济南250010 [2]山东省富铁矿勘查技术开发工程实验室,山东济南250010

出　　处：《山东理工大学学报（自然科学版）》2023年第2期29-33,共5页Journal of Shandong University of Technology:Natural Science Edition

摘　　要：南涝坡序列变角闪辉长岩是鲁西地区新太古晚期侵入岩重要组成部分。以野外地质调查为基础,结合前人年代学结果,对其岩石学、岩石地球化学和年代学进行研究,结果显示:岩石SiO_(2)质量分数为52.72%,Al_(2)O_(3)质量分数为15.62%,TiO_(2)质量分数为1.13%,MgO质量分数为5.00%,里特曼指数σ为0.54,属钙碱性岩;岩石明显富集大离子亲石元素(如Rb、Ba、Sr等),而相对亏损高场强元素(如Nb、Ta、P等)。岩石稀土元素总量较高,∑REE为165.62×10^(-6),显示为轻稀土元素相对富集的右倾型配分模式。主、微量及稀土元素特征反映出岩石具幔源岩浆的特点,但受到地壳物质的混染,岩浆的形成与基底构造活动密切相关。岩体形成于2550 Ma前后,对应于新太古代晚期第一个构造岩浆活动阶段,该期岩浆活动代表了鲁西大规模陆壳增生和克拉通化阶段的开始。Nanlaopo sequence metaamphibole gabbro is an important component of Late Neoarchaean intrusive rocks in western Shandong Province.Based on field geological survey and combined with previous chronological datas,its petrology,geochemistry and geo-chronology were studied.The result showed that the SiO_(2)content was 52.72%,Al_(2)O_(3)content was 15.62%,TiO_(2)content was 1.13%,MgO content was 5.00%.The Ritman indexσis 0.54,belonging to calc-alkaline rock series.The rocks were obviously enriched in large ion lithophile elements(such as Rb,Ba,Sr,etc.),while relatively depleted in high field strength elements(such as Nb,Ta,P,etc.).The total amount of rare earth elements in the rocks was relatively high,andΣREE was 165.62×10^(-6),showing a right leaning distribution pattern with relative enrichment of light rare earth elements.The major,trace and rare earth elements reflect the characteristic of mantle-derived magma,and showed that the magma might be contaminated by the crust material,and the formation of magma was closely related to basement tectonic activities.The rock mass formed around 2550 Ma,corresponding to the first tectonomagmatic activity stage in the Late Neoarchean,which represents the beginning of large-scale continental crust accretion and cratonization in western Shandong Province.

关 键 词：鲁西 南涝坡 新太古代晚期 辉长岩 地球化学 

分 类 号：P588.1[天文地球—岩石学] P597[天文地球—地质学]