摘要
本文对荷花坪锡多金属矿,锡田锡钨多金属矿以及新田岭钨矿矽卡岩中的石榴子石样品分别进行了主量元素、微量元素及红外光谱测定。结果表明,3种矽卡岩中的石榴子石多数属于(铁铝榴石+镁铝榴石+锰铝榴石)<15%的钙铁-钙铝榴石系列。新田岭钨矿的石榴子石中钙铁榴石端员含量明显高于其他两个锡矿。此外,在荷花坪、新田岭矿区发现了与后期铅锌矿化有关的锰质石榴子石。在单矿物尺度上,荷花坪矿区石榴子石核部富集钙铝榴石,边部富集钙铁榴石,而锡田矿区石榴子石与之相反;新田岭矿区石榴子石具有相对均匀的核部而边部发育细密的振荡环带。在稀土配分模式上,荷花坪矿区石榴子石重稀土富集,轻稀土亏损,δEu负异常较弱;锡田矿区石榴子石稀土总量最高,轻重稀土无明显分异,δEu负异常较弱;新田岭矿区石榴子石轻重稀土分异极强,重稀土富集,轻稀土严重亏损,δEu具显著的正异常。3种石榴子石的红外漫反射光谱均显示有10种吸收峰,其中低频区的5种与石榴子石成分中的钙铁榴石含量直接相关,因而造成新田岭矿区石榴子石的吸收峰与另两矿区石榴子石相比显著向低频波段移动。通过对华南3类含钨锡矽卡岩中的石榴子石的研究,确认了石榴子石的形成与矽卡岩形成中热液体系的环境变化密切相关。微量元素分析与红外光谱技术作为近年来矽卡岩型石榴子石研究的热点,能够提供传统研究中所不能涉及的微观信息。
This paper focuses on major element,trace element and inferred spectrum of garnet in skarns from Hehuaping Sn-polymetallic deposit,Xitian W-Sn-polymetallic deposit and Xintianling W deposit.The results show that most garnets in these three types of skarns belong to andradite-grossularite series with almandite＋spessartine＋pyrope component less than 15%.Andradite component in garnet from Xintianling W deposit is significantly higher than those of the other two deposits.Furthermore,manganese garnets related to Pb-Zn mineralization are discovered in Hehuaping and Xintianling deposits.On a scale of one particle,garnet from Hehuaping deposit has a core rich in grossularite while rims rich in andradite.Garnet from Xitian deposit has opposite variation tendency from Hehuaping deposit.Garnet from Xintianling deposit has a relatively homogeneous core while fine oscillation bands are developed in rims.The REE distribution pattern shows HREE enrichment characteristics with a weak negative anomaly of δEu.Garnet from the Xitian deposit has the highest ΣREE,with weak negative anomaly of δEu but shows no obvious differentiation between LREE and HREE.Garnet from Xintianling deposit shows obvious differentiation between LREE and HREE,rich in HREE and extremely depleted in LREE with significantly positive anomaly of δEu.Garnet from all three types of skarn shows ten absorption peaks,among which five in low frequency areas are directly related with the component of andradite.Therefore,the peak positions of garnet from Xintianling deposit are obviously shifted toward the low frequency direction comparing with those from the other two deposits.This work confirms the close relationship between the formation of garnet and the change of hydrothermal system during skarnization.As a hotspot in garnet research,trace element composition and inferred spectrum are able to provide microscopic information which can not be obtained by traditional analysis.
出处
《矿物学报》
CAS
CSCD
北大核心
2013年第3期315-328,共14页
Acta Mineralogica Sinica
基金
国家重点基础研究发展计划项目(编号:2012CB416702)
国家自然科学基金项目(批准号:41273053)
中国地质调查局项目(编号:1212011085407)
