印尼塔里亚布锡铁多金属矿床矿浆型磁铁矿的矿物学特征与形成机理探讨  

The Mineralogical Characteristics and Mechanism Discuss of Ore-magma Type Magnetite from Taliabu Sn-Fe Polymetallic Deposit,Indonesia

作　　者：丁俊[1] 张术根[1] 徐忠发 秦新龙 

机构地区：[1]中南大学地球科学与信息物理学院有色金属成矿预测教育部重点实验室,湖南长沙410083 [2]有色金属华东地质勘查局,江苏南京210007

出　　处：《矿物学报》2012年第2期259-268,共10页Acta Mineralogica Sinica

摘　　要：在野外地质观察基础上,运用光学显微镜、化学分析、X射线衍射、扫描电镜、流体包裹体成分分析等手段,对印尼塔里亚布锡铁多金属矿床中矿浆型磁铁矿的矿物学特征进行了研究。结果表明,矿浆型铁矿体界线清晰,呈贯入充填形态,围岩蚀变简单。矿石具块状条带、气孔状、流纹状、熔结瘤状等典型矿浆型铁矿石构造。矿石矿物组成简单,磁铁矿含量高,磷灰石+磁铁矿是标志性矿物组合。磁铁矿在化学成分上富铁(TFe=66.08%～68.01%)、富镁(MgO=3.05%～3.22%)、贫硅(SiO2=0.82%～1.91%)、贫碱(Na2O+K2O<1.06%),具明显铕负异常(δEu=0.14～0.55)。磁铁矿晶胞参数介于0.8390～0.8397 nm,接近标准值。磁铁矿晶体以致密它形晶为主,重结晶形成的三晶嵌连结构反映矿浆冷凝结晶是典型的退火过程。磁铁矿流体成分富集Li+(0.234μg/g)、Na+(3.438μg/g)等碱性阳离子及H2O(4129μg/g)、SO42-(8.916μg/g)及其它挥发性组分。在富碱、富挥发分和高氧逸度条件下,研究区矿浆型铁矿与花岗岩是酸性原始岩浆高度演化分异的同源产物。On the basis of field investigation,mineralogical characteristics of ore-magma type magnetite were studied by the means of optical microscopy,X-ray diffraction,scanning electronic microscopy,chemical analysis and fluid inclusion composition analysis of Taliabu Sn-Fe polymetallic deposit,Indoneisa.The results show that ore-magma type ore body with an injection and filling shape has a clear boundary with all rocks with simple alterations.Iron ores has typical fabric of iron ore-mamga type including bulk band structure,vesicular structure,rhyotaxitic structure,sintered nodular structure and tricrystal embedded linked texture.The mineral assemblage is simple.Magnetite is main mineral.The apatite with magnetite is the typical mineral assemblage.The magnetite is high in TFe （66.08%~68.01%）,MgO （3.05%~3.22%）,low in silicon （SiO2=0.82%~1.91%）,alkali （Na2O＋K2O〈1.06%） and intensive depletion of Eu （δEu=0.14~0.55）.The cell parameter is closed to standard value between 0.8390~0.8397 nm.The crystal form of magnetites are mainly in dense,fine grained and xenomorphic.Triple junction texture by recrystallization indicates that the cooling and crystallization of ore-magma is the typical annealing process.There is high content of alkaili ion as Li＋（0.234 μg/g） and Na＋（3.438 μg/g） and volatile components as H2O（4129 μg/g） and SO42-（8.916 μg/g） in fluid inclusion composition.Under the condition of high in alkali,volatile components and oxygen fugacity,the ore-magma type magnetite and granite are congenetic products by complete evolution and differentiation of acid mother magma.

关 键 词：塔里亚布岛 矿浆 磁铁矿 矿物学 酸性侵入岩 

分 类 号：P571[天文地球—矿物学] P611.1[天文地球—地质学]