内蒙古罕山林场地区下二叠统本巴图组碎屑岩地球化学特征及物源区构造背景分析

Geochemical Characteristics and Tectonic Background Analysis of the Lower Permian Benbatu Formation Clastic Rocks of the Hanshan Forest Farm Area in Inner Mongolia

本巴图组为罕山林场地区最古老地层,主要为一套轻微变质的深海沉积碎屑岩与少量火山岩组合。对8件轻微变质碎屑岩进行地球化学测试分析,结果显示主量元素具高硅特征,说明岩石中具有较高含量的石英或富含SiO 2的矿物,富铝特征与岩石中长石、云母、黏土矿物等富铝矿物有关。岩石稀土总量高,轻重稀土具明显的分馏作用;稀土标准化曲线解释了沉积物源岩主要来自上地壳,并且物源较单一。经物源区构造背景判别图解及与不同大地构造背景进行对比,结果表明本巴图组碎屑岩源区构造背景为大陆岛弧或活动大陆边缘。

The Benbatu Formation is the oldest formation in the Hanshan Forest Farm area,mainly composed of a set of slightly metamorphosed deep-sea sedimentary clastic rocks and a small amount of volcanic rocks.Geochemical testing and analysis are conducted on 8 slightly metamorphosed clastic rocks,and the results show that the main elements have high silicon characteristics,indicating a high content of quartz or SiO 2 rich minerals in the rocks.The aluminum rich characteristics are related to aluminum rich minerals such as feldspar,mica,and clay minerals in the rocks.The total amount of rare earths in rocks is high,and the light and heavy rare earths have obvious fractionation effects.The standardization curve of rare earth elements explains that the sediment source rocks mainly come from the upper crust and have a relatively single source.Through the identification diagram of the tectonic background of the source area and comparison with different tectonic backgrounds,the results indicate that the tectonic background of the clastic rock source area of the Benbatu Formation is a continental island arc or active continental margin.