Cassiterite as a record of Sn mineral system processes

Research output: Chapter in Book/Conference paperConference paper

Abstract

Cassiterite (SnO2) is associated with mineral systems enriched in the 'critical' metals W, Nb, Ta, Li and In (Chakhmouradian et al. 2015) and is a potential multi-process recorder of these mineralised systems. Cassiterite is known to display complex cathodoluminescent microstructures, however detailed physicochemical models for their formation are yet to be established. Here we present a panchromatic CL, hyperspectral CL and quantitative X-ray element map study of these microstructures in cassiterite, along with observations from EPMA and LA-ICP-MS trace element datasets.

We show that sector zoning imparts a significant control on W and Fe distribution within cassiterite and that CL imaging alone does not reveal the full microstructural history with high Fe, Ta, Nb or W contents in cassiterite. We also show that the previously reported coupled substitution mechanisms for W, Nb and Ta into cassiterite cannot account for the high contents observed in some samples, and that different sectors within the same crystal show different preferred substitutional stoichiometries. Furthermore, we discuss unusual Nb/Ta and Zr/Hf ratios which imply the existence of fractionation processes during hydrothermal-metasomatic Sn mineralisation that can drive the Nb/Ta ratio to large values in excess of chondritic ratios (Nb/Ta >> 100).

Original languageEnglish
Title of host publicationLife with ore deposits on Earth, Proceedings of the 15th SGA Biennial Meeting, 2019, Vols. 1-4
PublisherSociety for Geology Applied to Mineral Deposits
Pages134-137
Number of pages4
Publication statusPublished - 2019
Event15th SGA Biennial Meeting on Life with Ore Deposits on Earth - Glasgow, United Kingdom
Duration: 27 Aug 201930 Aug 2019

Conference

Conference15th SGA Biennial Meeting on Life with Ore Deposits on Earth
CountryUnited Kingdom
CityGlasgow
Period27/08/1930/08/19

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