Geochemical characteristics, source area properties and tectonic significance of Ore bearing metasedimentary rocks from Tebai gold deposit in Alxa right banner area
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摘要: 本次对阿拉善右旗特拜金矿赋矿变沉积岩进行地球化学分析，主要岩性为云母石英片岩、变质粉砂岩、变质岩屑石英砂岩等；主量元素SiO2平均含量62.39%，Al2O3平均含量15.40%，Fe2O3平均含量6.57%，MgO 平均含量3.84%，CaO 平均含量2.31%，K2O 平均含量2.65%，Na2O 平均含量2.09%。ΣREE 配分模式曲线一致，LREE/HREE=5.75～8.34，平均为7.18，（La/Yb）N=5.39～8.38，平均6.83，Eu负异常明显，轻稀土元素相对重稀土元素明显富集；微量元素中相对稳定元素比值如La/Sc、Th/Sc、Cr/Zr显示出物源来自上地壳长英质；Rb-K2O图解、Ni-TiO2图解和La/Yb-ΣREE图解表明其母岩主要来源于花岗岩，结合古水流特征以及碎屑锆石年龄证据等推测物源可能来自北大山地区花岗岩。结合特拜赋矿变沉积岩岩石组合特征、构造特征和地球化学特征，认为其源岩形成于大陆岛弧构造环境。Abstract: In this paper, geochemical analysis of the ore bearing metasedimentary rocks of the Tebai gold deposit in Alxa Right Banner is carried out, The main lithology is mica quartz schist, metamorphic siltstone, metamorphic lithic quartz sandstone, etc; The average content of SiO2 is 62.39%, the average content of Al2O3 is 15.40%, the average content of Fe2O3 is 6.57%, the average content of MgO is 3.84%, the average content of CaO is 2.31%, the average content of K2O is 2.65%, the average content of Na2O is 2.09%.The REE patterns of curves are consistent, LREE/HREE=5.75~8.34, the average value is 7.18,(La/Yb)N=5.39~8.38, the average value is 6.83, Eu negative anomaly is obvious, LREE are obviously enriched relative to HREE; Rb-K2O diagram、Ni-TiO2 diagram and La/Yb-ΣREE diagram show that the parent rocks may originate from granites; Combined with paleocurrent characteristics and detrital zircon age evidence, it is speculated that the provenance may come from granite in Beidashan area.Combined with the rock assemblage characteristics, tectonic combined characteristics and Geochemical characteristics of Ore bearing metasedimentary rocks in Tebai, it is considered that the source rocks were formed in a tectonic environment of continental island-arc.
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Key words:
- Alxa block /
- Tebai gold deposite /
- ore-hosting strata /
- Metasedimentary rock /
- geochemistry /
- continental island-arc
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