腾冲地块稀土地球化学背景与泥岩中稀土超常富集特征

Geochemical Background of REEs:Super-enrichment in Argillaceous Rocks in Tengchong Block

近年来围绕腾冲地块花岗岩取得了一系列重要稀土勘查突破,深入了解稀土元素地球化学背景是稀土矿产勘查的基础。系统总结腾冲地块全国地球化学基准值和区域化探扫面获得的水系沉积物和9个主要地质单元岩石的稀土元素分布,查明区域稀土元素地球化学背景。稀土元素主要在新近系泥岩、白垩纪花岗岩和全新世火山岩,其中新近系芒棒组泥岩具有稀土超常富集,稀土平均含量达444×10–6,是地壳克拉克值的3倍,并与水系沉积物La地球化学异常具有空间对应关系,结合区域地质成矿条件和新类型稀土矿成矿特点,认为除白垩纪花岗岩以外,腾冲地块芒棒组泥岩和全新世火山岩可能具有形成稀土矿的潜力。

In recent years,a series of exploration breakthroughs were made for rare earth elements(REEs)deposits related to granite in Tengchong block.The concentrations and distribution of REEs in rocks and stream sediments of 9 main geological units obtained from“China Geochemical Baseline Project”(CGB)and the“Regional Geochemistry National Reconnaissance Project(RGNR)”of the Tengchong block were systematically summarized.REEs are enriched in the granite,Tertiary sedimentary rocks and Holocene volcanic rocks,and particularly enriched in argillaceous rocks of Mangbang Formation.La geochemical anomalies based on stream sediment data have the spatial correlation with Mangbang Formation and Holocene volcanic rocks.These facts imply that Tertiary argillaceous rocks and Holocene volcanic rocks may have potential for new type REE deposits in Tengchong.