云南姚安县老街子碱性杂岩体特征及稀土找矿前景

云南姚安县老街子杂岩体为一弱酸性富钾的碱性岩体,其物质组分来源于地幔,同时也混染了部分地壳组份,地质年代为34.9~31.3Ma。该杂岩体群包括浅成侵入岩类和喷出岩类两大类,前者以黑云母正长斑岩、正长斑岩为代表,后者以黑云母粗面岩为代表。杂岩体具有较高稀土元素背景值,TREE平均值为904.64μg/g,其中LREE平均值达到853.65μg/g,不同类型岩石的轻重稀土分馏程度虽然存在一定的差异,但均分馏作用明显,(La/Yb)N平均值达55.6;杂岩体具有一定分布面积的风化壳,对有找寻离子吸附型轻稀土矿床有较好的前景。

THE FEATURE AND REE PROSPECTING POTENTIALITY OF LAOJIEZI ALKALINE COMPLEX BODY IN YAOAN,YUNNAN

Laojiezi complex in Yaoan,Yunnan is an alkaline rockbody with weak acidity and rich in K,which is mantle derived and contaminated with some crust components.The geological age is 34.9-31.3 Ma.This complex body is composed of epi-intrusive and volcanic rocks.The former is representative by biotite syenite-porphyry,syenite-porphyry,the latter is biotite trachyte.The complex body is with the high REE background value.TREE average 904.64μg/g,LREE average 853.65μg/g.The LREE,HREE fractional distillation degree of different rock is somewhat different one another,however the fractional distillation of them is evident all in all.(La/Yb)N average 55.6.The complex body has a certain area of weathering crust and the good potentiality of prospecting for the ion absorbed LREE deposit.