河南省安林地区接触交代型铁矿稀土元素地球化学特征

REE geochemical characteristics of contact metasomatic Fe deposit in Anlin area,Henan province

安林地区铁矿属典型的接触交代型铁矿,与成矿作用有关的岩浆岩为燕山期闪长岩,奥陶系马家沟组第三岩性段是主要的赋矿地层。通过对该矿区与成矿相关的岩矿石稀土元素地球化学研究表明:闪长岩w(ΣREE)_(平均)=114.12×10^(-6),灰岩w(ΣREE)_(平均)=11.98×10^(-6),磁铁矿石w(ΣREE)_(平均)=26.13×10^(-6),矽卡岩w(ΣREE)_(平均)=65.67×10^(-6),磁铁矿石和矽卡岩的稀土总量介于闪长岩与灰岩之间;稀土配分曲线总体上都表现为轻稀土相对富集的右倾型;闪长岩一般具有极弱的正Eu异常,灰岩具有较明显的负Eu异常,矽卡岩具有较弱的负Eu异常,磁铁矿石具弱的正Eu异常或Eu异常不明显;岩矿石的δCe值非常接近,且均不显示或显示极弱的负Ce异常;铁矿石和矽卡岩继承了来自闪长岩和灰岩的稀土元素特征,结合S、Pb同位素特征,认为闪长岩提供了主要成矿物质,赋矿地层也可能提供了部分成矿物质。

Fe deposit in Anlin area is typical contact metasomatic ore deposit.Yanshanian diorite is the Fe ore-related rock.The Fe ore is hosted by the third lithologic member of Majiagou formation.REE geochemistry of the ore-related rocks is studied.Average w(ΣREE)of diorite is 114.12×10^(-6),average w(ΣREE)of limestone 11.98×10^(-6),average w(ΣREE)of magnetite ore 26.13×10^(-6),average w(ΣREE)of skarn 65.67×10-6,w(ΣREE)of the magnetite ore and skarn is between those of the diorite and limestone.REE distribution curve generally dip rightly with relative enrichment of LREE.The curve of diorite is characterized by extremely weak positive Eu anomaly,limestone obviously negative Eu anomaly,skarn relatively weak Eu anomaly,magnetite ore weak Eu anomaly or unobvious Eu anomaly.Ce values of the rock and ore are proximate with weak Ce anomaly or without Ce anomaly.REE characteristics of magnetite ore and skarn are inherited from those of the diorite and limestone which together with S,Pb isotropic data suggest that the diorite may provide main ore materials and the host rock some for the contact metasomatic Fe deposit.