闽西南地区早白垩世两类花岗质岩体地球化学异同及其与成矿作用关系

The Differences of Geochemical Characteristics and Relative with Ore-Forming Processes of Two Types Early-Craceous Granites in Southwestern Fujian Province

本文通过地球化学方法对闽西南地区与不同成矿作用有关的岩体地球化学差异性进行了研究。闽西南地区花岗质岩石分为两种类型:一种与铜金成矿作用有关,以才溪、四方和罗卜岭岩体为代表,岩石类型多为花岗闪长岩;一种与铁成矿作用有关,以莒舟岩体和太华岩体为代表,岩石类型多为花岗岩。地球化学证据表明前者地球化学特征上显示为壳幔混源型花岗岩,分异程度低,稀土配分属轻稀土富集型,具中等的Eu/Eu*负异常,其中四方和罗卜岭岩体形成过程中幔源物质的加入对成矿作用影响大;后者分异程度高,稀土配分模式为稍向右倾的V字型,具有较强的Eu/Eu*负异常,这种高演化的花岗岩对铁矿床的形成起到了富集作用。

This study focuses on the geochemical difference of the pluton relative with Ore-forming granites in the Southwest of Fujian province. The granites can be devided into two types： one type is relative with Cu-Au Ore forming processes, which is represented by Caixi pluton, Sifang pluton and Luoboling pluton, another type is Juzhou and Taihua Plutons, rocks type is granite, which relative with Fe Ore-forming. According to their geochem ical characteristics, we propose that the former is belong to crust-mantle mixed source type granite, characterized by low evolution, LREE enrichment, and Medium negative Eu/Eu＊ anomalies, in addition, the mantle-sourced ma- terials play important roles in the ore-forming when Sifang and Luoboling plutons forming; the latter is character ized by high degree of differentiation and evolution, and slightly right tendency V-type pattern of REE distribution, and strong negative Eu/Eu＊ anomalies, these high evolution granites played an active role in Fe enriching.