摘要
巴尔哲超大型稀土铌铍锆矿床位于内蒙古自治区扎特鲁旗。矿体赋存在钠闪石花岗岩中，成矿元素主要赋存在兴安石、铌铁矿、烧绿石和锆石中。钠闪石花岗岩侵入在大兴安岭侏罗世火山岩盆地中，矿区位于大兴安岭主脊－林西断裂带与嫩江－八里罕断裂带之间的霍林河东西向断裂带和大兴安岭－太行山－武陵山重力梯度带上。钠闪石花岗岩的Ｒｂ－Ｓｒ等时线年龄为１２５Ｍａ。矿体遭受强烈交代作用，主要为钠闪石化和硅化。巴尔哲钠闪石花岗岩是岩浆强烈分异的产物，它的稀土分布模式为Ｖ型，铕强烈亏损。铷含量很高，而Ｓｒ和Ｂａ很低，Ｆ含量高。Ｋ／Ｒｂ和Ｚｒ／Ｈｆ比值很低，Ｒｂ／Ｓｒ比值很高。花岗岩物质来源于富集地幔εＮｄ（Ｔ）为１．８８—２．４７，锶初始值＜０．７０５，石英δ１８Ｏ为５．２‰—６．０‰。成矿机制是：富集地幔低程度部分熔融形成的岩浆在水和挥发分的作用下强烈分异，并在岩浆晚期产生强烈的自交代作用。
The Baerzhe ore deposit in Jarud Qi,Nei Mongol Autonomous Region is a REE Nb Be Zr superlarge deposit.The ore bodies occur in the riebechite granites.The REE Nb Be Zr are mainly partitioned into xinanite,columbite,pyrochlore and zircon.The deposit is located in Huolinhe east west fault,which is between Da Hinggan Ling Linxi fault and Nen Jiang Balihan fault and gravity gradient belt of Da Hinggan Ling Taihang Shan Wu Ling Shan.Riebeckite granites emplaced in Jurassic volcanic basin of Da Hinggan Ling and its Rb Sr isochron age is 125 Ma.Ore bodies are intensively metasomatized by albitization and silicification.Riebeckite granites are the products of strong magmatic differentiation.They have V type REE patterns with intense Eu depletion,positive Ce anomalies and M tetrad effect.The contents of Rb and F are high in the granites whereas Sr and Ba are low.Ratios of K/Rb and Zr/Hf are low and Rb/Sr is high.On the basis of isotopic composition(ε Nd (T)=1.88—2.47, 87 Sr/ 86 Sr) i<0.705,δ 18 O=5.2‰—6.0‰),we conclude that riebeckite hranites were derived fron the enriched mantle. Ore—forming mechanism is that magma formed by low degree or paartial melting of enriched mantle underwint strong differetiation with the presence of water and volatile leading to the formation of riebeckite granites.The granites were then repeatedly autometasomatized at late stage of magma,resulting in the formation of the superlarge deposit.
出处
《地球化学》
CAS
CSCD
北大核心
1997年第1期24-35,共12页
Geochimica
关键词
稀土元素矿床
铌矿床
铍矿床
锆矿床
地球化学
superlarge deposit,riebechite granite,magmatic differentiation,metasomatism,Nei Mongol Autonomous Region
