方城县柏树岗金红石矿床^(40)Ar-^(39)Ar法年龄及其地质意义

^(40)Ar-^(39)Ar Age and Its Geological Significance of Baishugang Rutile Deposit

柏树岗金红石矿床有三次成矿作用:第一次为角闪岩相变质成矿作用,形成了粗粒金红石;第二次也为变质成矿作用,变质条件为角闪岩相与绿片岩相间的过度相,形成了细粒金红石;第三次为热液成矿作用,形成了脉状金红石。前两次为主要成矿作用。本文报道的的40Ar-39Ar法坪年龄416.1±0.5Ma为第二次变质成矿作用年龄,前人报道的Rb-Sr等时线年龄1180±50Ma为第一次变质成矿作用年龄。找矿方向:粗粒金红石矿体为新元古代角闪岩相变质带,细粒金红石矿体为加里东期变质条件略低(角闪岩相与绿片岩相间的过度相)的变质带。

The Baishugang rutile deposit has suffered two metamorphic mineralizations that are mail mineralizations and one hydrothermal mineralization.First metamorphic mineralization that achieves amphibolite facies formats coarse rutile,and second metamorphic mineralization that achieved the facies between amphibolite facies and green facies formats fine rutile.The age of the second metamorphic mineralization is ＂416.1±0.5Ma＂,and the age of first metamorphic mineralizations is ＂1180±50Ma＂.Direction for coarse-rutile orebody is Late Proterozoic amphibolite-facies metamorphic-belt and direction for coarse-rutile orebody is Caledonian metamorphic-belt of the facies between amphibolite facies and green facies.