滇东南新寨锡矿床夕卡岩矿物学特征及其地质意义  

Mineralogical characteristics and geological implications of skarn minerals in the Xinzhai tin deposit,SE Yunnan,China

作　　者：张琪 任涛[1] ZHANG Qi;REN Tao(Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming 650093,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093

出　　处：《矿物岩石地球化学通报》2023年第6期1410-1423,共14页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(42163005)。

摘　　要：新寨夕卡岩型锡矿床位于华南板块西南缘,属于接触交代型夕卡岩矿床,其围岩主要为片岩和大理岩。为查明该矿床夕卡岩矿物的形成环境和变质过程中元素的富集规律,开展了夕卡岩矿物化学成分和元素空间分布测试分析。结果显示,新寨辉石成分为Di_(76-79)Hd_(20-22)Jo_(1),以透辉石为主;石榴子石成分为Alm_(61-74)Gr_(18-26)Ad_(0-3),以铁铝榴石为主;角闪石主要为钙镁闪石。石榴子石球粒陨石标准化稀土元素配分模式总体表现为LREE亏损,MREE和HREE富集的特征,表明其可能形成于还原环境。印支期区域变质作用导致矿区中的岩石和矿物变形,同时石榴子石边缘形成了Mn、Sc、Y和HREE富集环带。研究认为,新寨夕卡岩矿床形成与加里东期岩浆侵位有成因联系。The Xinzhai skarn tin deposit is located in the southwestern margin of the South China block.It belongs to the contact metasomatic type skarn deposit.Its wallrocks are mainly calcareous schist and marble.In order to identify the formation environment of skarn minerals of the deposit and its elemental enrichment rules during metamorphism,in this work,we have analyzed the chemical compositions of skarn minerals and the elemental distribution of garnet in the Xinzhai deposit.The results show that pyroxenes of the deposit have variable compositions of Di_(76-79)Hd_(20-22)Jo1.Garnets have compositions of Alm_(61-74)Gr_(18-26)Ad_(0-3).Amphiboles mainly belong to the calcium magnesium amphibole.The chondrite-normalized REE patterns of the garnets generally characterized with the LREE depletion and the MREE and HREE enrichment,indicating that they were formed in a reduced environment.The Indosinian regional metamorphism resulted in the deformation of minerals and rocks(skarn and granite),and the formation of Mn-,Sc-,Y-,and HREE-enriched rims of the original garnet grains.It is believed that the formation of Xinzhai skarn deposit could be genetically related to the Caledonian magmatic emplacement.

关 键 词：夕卡岩 新寨锡矿床 矿物学 区域变质 LA-ICP-MS 

分 类 号：P618.44[天文地球—矿床学]