攀枝花铁矿床两种类型铁矿体中角闪石组分特征及其对矿床成因的指示意义  

Characteristics of Amphibole Components in Two Types of Iron Ore Bodies in Panzhihua Iron Deposit and Their Indicative Significance for the Ore Deposit Genesis

作　　者：罗伟 李佑国[2] 金廷福 彭静 LUO Wei;LI Youguo;JIN Tingfu;PENG Jing(College of Engineering and Technology,Zunyi Normal University,Zunyi 563002,Guizhou,China;College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China;College of Mining Engineering,Guizhou University of Engineering Science,Bijie 551700,China)

机构地区：[1]遵义师范学院工学院,贵州遵义563006 [2]成都理工大学地球科学学院,四川成都610059 [3]贵州工程应用技术学院矿业工程学院,贵州毕节551700

出　　处：《昆明理工大学学报（自然科学版）》2023年第5期38-49,共12页Journal of Kunming University of Science and Technology(Natural Science)

基　　金：贵州省科学技术基金项目(ZK[2021]204);中国地质调查局项目(1212011220921);遵义师范学院项目(BS[2020]5);毕节市科学技术联合基金项目([2019]22)。

摘　　要：攀枝花铁矿床朱家包包矿段内似层状和脉状铁矿体中的铁矿石普遍发育单斜辉石的角闪石反应边和斜长石的角闪石镶边,对此类角闪石进行了岩相学及电子探针分析,讨论了铁矿床形成过程中流体的作用及深部岩浆过程.结果表明,两种类型铁矿石中的此类角闪石,其(Ca+Na)_(B)大于1.5、Na_(B)小于0.5(0.07~0.17)、Mg/(Mg+Fe^(2+))为0.69~0.76、^(Ⅳ)Si为5.85~6.13,为镁钙闪石,其w(Al_(2)O_(3))为11.05%~14.32%,w(TiO_(2))为2.73%~5.15%,为幔源岩浆成因.似层状铁矿体中角闪石的形成温度为1 003~1 049℃,氧逸度NNO-0.25~+0.10,脉状铁矿体中角闪石的形成温度为998~1 044℃,氧逸度NNO+0.34~+0.67.结合前人的研究,本文认为是深部富水流体注入攀枝花地区深部多重岩浆房,诱发初步富集铁钛的熔体发生不混熔形成富铁钛熔体,持续注入的深部流体在萃取了富铁钛熔体中的铁钛组分、并携带了部分残余熔体和先期结晶的造岩矿物,形成了富水、富铁钛熔体-流体流.这种熔体-流体流注入半固结的攀枝花浅部岩浆房中,溶蚀先期结晶形成的造岩矿物,形成溶蚀结构,且使残余岩浆富水,富水残余岩浆与先期结晶的造岩矿物不平衡,反应形成了单斜辉石的角闪石反应边和斜长石的角闪石镶边,铁钛质组分在硅酸盐矿物粒间结晶并沉淀到底部,形成了似层状铁矿体.脉状铁矿体是富水、富铁钛组分熔体-流体流贯入已固结的辉长岩体及围岩中,排气沉淀形成的.The amphibole reaction rim of clinopyroxene and the amphibole braiding rim of plagioclase are generally developed in the layered and vein-like iron ore bodies in the Zhujiabaobao ore section of the Panzhihua iron deposit.Based on the petrography and electron probe analysis of this type of amphibole,the fluid action and deep magmatic process during the formation of iron deposit are discussed.The geochemical analysis of these amphiboles in the two types of iron ores shows(Ca+Na)_B1.5、Na_(B) 0.5(0.07~0.17)、Mg/(Mg+Fe~(2+))=0.69~0.76、~ⅣSi= 5.85~6.13,belongs to tschermakite.The geochemical analysis of these amphiboles shows w(Al_2O_3)= 11.05%~14.32%,w(TiO_2)= 2.73%~5.15%,belongs to mantle-derived magmatic amphibole.According to the composition of hornblende,the formation temperature of hornblende in the layered iron orebody is estimated to be 1 003 ~ 1 049 ℃,fO_(2) varies from NNO-0.25 to NNO +0.10,the formation temperature of hornblende in the vein iron orebody is estimated to 998~ 1 044 ℃,and fO_(2) varies from NNO + 0.34 to NNO + 0.67.Combined with the previous studies,this paper argues that after the water-rich deep fluid injected into the deep magma chambers in the Panzhihua area,the melt in the deep magma chambers occured liquid immiscibility and formed Fe-Ti-rich melts.After extracting the Fe and Ti components in the Fe-Ti-rich melt and carrying part of the residual melt and the pre-crystallized rock-forming minerals,the deep-penetrating fluid formed the Fe-Ti-rich melt-fluid flow.The layered iron orebodies were formed by injecting Fe-Ti-rich and H_2O-rich melt-fluid flow into the semi-consolidated Panzhihua shallow magma chamber and dissolving the rock minerals formed by the previous crystallization,and resulting in the iron-titanium component precipitating and crystallizing between the silicate mineral grains.At the same time,some of the water in the Fe-Ti-rich,water-rich melt-fluid flow was absorbed by the residual magma in the Panzhihua shallow magma Chamber to form water-rich magma,which was not

关 键 词：角闪石 熔体-流体流 结晶条件 攀枝花铁矿床 

分 类 号：P618.31[天文地球—矿床学]