内蒙古西乌旗阿拉坦高勒含矿辉长岩岩石学特征及其成因

内蒙古西乌旗阿拉坦高勒含钒钛磁铁矿的辉长岩岩体主要由中--粗粒的狭义辉长岩、角闪辉长及橄榄辉长岩、细粒辉长岩和辉绿岩等复合而成。不同钻孔岩心的主量、微量和稀土元素分析结果研究发现，Al₂O₃ 含量为14. 5% ～ 19. 65%，K₂O + Na₂O 含量为3. 03% ～ 4. 7%，P₂O₅ 含量为0. 11% ～ 1. 04%，总体上，主量元素具有高铝、低碱、不均匀富磷的特点，属于里特曼指数σ ＜ 4 的钙碱性系列岩石。( La /Yb) N 为1. 40 ～ 6. 54，( Gd /Yb) N 为1. 38 ～ 2. 09，表现为轻稀土富集的右倾型，表明岩浆来源于地幔物质的低程度部分熔融。辉长岩δEu 为0. 53 ～ 1. 18，Eu 元素异常的不同表现形式和相似的微量元素配分特点，一方面揭示了不同岩石类型具同源性特点，另一方面结合岩相学研究，也为该岩体历经岩浆分离结晶--多期脉动侵位--流体叠加成矿的成因机制提供了地球化学依据。

Petrobogical characteristics and petrogenesis of Alatan Gol ore-bearing gabbro in West Ujimqin Banner, Inner Mongolia

The Alatan Gol vanadium titanomagnetite ore-bearing gabbro plutons are mainly composed of medium-coarse grained gabbro in narrow sense, amphibole gabbro, and olivine gabrro, fine-grained gabbro and diabase in West Ujimqin Banner, Inner Monglia. The study on major, trace and REE elements of various drilling cores shows the content of A1203 as 14.5% - 19.65%, K2O ＋ Na2O as 3.03% -4.7%, and P205 as 0.11% 1.04%. The major elements are characterized by high-A1, low-alkali and uniform phosphorus-rich, belonging to calc-alkaline series with Rittman index less than 4. The content of （La/Yb） N is 1. 40 - 6. 54, and （Gd/Yb） N as 1. 38 - 2. 09, which shows LREE enrichment and right slope, indicating the magma derived from the mild partial melting of mantle. The δEu of gabbro is 0.53 -1.18 in content, and the different expression forms of Eu anomaly and similar distribution characteristics of trace elements, reveal that the various rock types deprived from the ho- mogenous source on the one hand, and provide geochemistry basis for genetic mechanism of fractional crystalliza- tion, multi-phase pulse emplacement and fluid superimposed mineralization on the other hand combining with the petrography study.