کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6435590 | 1637226 | 2017 | 25 صفحه PDF | دانلود رایگان |
- A sediment-hosted Nb-Zr-REE-Ga mineralization in SW China was described.
- The mineralization was initially derived from Emeishan alkaline volcanic ashes.
- The alkaline volcanic ashes were altered by subsequent hydrothermal fluids.
- A critical element-enrichment model has been proposed for this Nb-Zr-REE-Ga deposit.
- The mineralization has giant economic potential.
A previous study briefly described the occurrence of a new type of Nb(Ta)-Zr(Hf)-REY-Ga (REY: rare earth elements and yttrium) polymetallic mineralization in eastern Yunnan, southwest China. In this paper, the mineralogical and geochemical features have been further advanced through a study of two regionally extensive and relatively flat-lying mineralized layers from No. XW drill core. The layers are clay-altered volcanic ash and tuffaceous clay, and are dominated by clay minerals (mixed layer illite/smectite, kaolinite, berthierine, and chamosite); with lesser amounts of quartz and variable amounts of anatase, siderite and calcite; along with trace pyrite, barite, zircon, ilmenite, galena, chalcopyrite, and REE-bearing minerals. The mineralized samples have higher Al2O3/TiO2 values (13.7-41.4) and abundant rare metal elements (Nb, Ta, Zr, Hf, REE, Ga, Th, and U) whereas less mineralized samples are rich in V, Cr, Co, and Ni and have lower Al2O3/TiO2 values (2.32-7.67). The mineralized samples also have strong negative δEu in chondrite-normalized REE patterns. Two processes are most likely responsible for the geochemical and mineralogical anomalies of the mineralized samples: airborne volcanic ash and multi-stage injection of low-temperature hydrothermal fluids. Based on paragenetic analysis, this polymetallic mineralization is derived from the interaction between alkaline volcanic ashes and subsequent percolation of low-temperature fluids. The intense and extensive alkaline volcanism of the early Late Permian inferred from this study possibly originated from the coeval Emeishan large igneous province (ELIP). This unique Nb(Ta)-Zr(Hf)-REE-Ga mineralization style has significant economic and geological potential for the study of mineralization of the lowest Xuanwei Formation.
Journal: Ore Geology Reviews - Volume 80, January 2017, Pages 116-140