Titanite as an indicator mineral in porphyry systems
File(s)
Author(s)
Matthews, Tom
Type
Thesis
Abstract
Titanite is an accessory mineral that is commonly found in rocks associated with porphyry copper deposits, either as a primary igneous or secondary alteration mineral. Compositions of titanite, with supporting whole-rock and mineral chemistry were characterised from four study sites: Strontian, Chuquicamata, Cobre Panama and Oyu Tolgoi. Titanite data from these sites were combined with data from a global sample suite and literature data, to characterise and understand signatures of titanite related to porphyry mineralisation.
Primary and secondary titanites display contrasting compositions, as exemplified by F, Al, Sc, LREE and Th contents. Primary titanite linked to mineralisation can potentially be detected using supervised learning techniques, which identify Mn and Sr concentrations, as well as Eu/Eu* ratios and lambda values as important discriminators. Igneous titanite compositions are influenced by both bulk magma chemistry and late-stage residual melt chemistry, with important implications for false positives when applying conventional techniques to mineral prospectivity studies.
Determining trace element chemistry and U-Pb isotopic compositions in both igneous and non-igneous titanite reveal the potential in recognising the presence of multiple titanite populations in the same rock. This is recommended as a means to identify porphyry titanite, allowing U-Pb ages to be related to mineralising events of a particular age. Overall, this study highlights the potential utility of titanite as an indicator mineral in porphyry copper systems.
Primary and secondary titanites display contrasting compositions, as exemplified by F, Al, Sc, LREE and Th contents. Primary titanite linked to mineralisation can potentially be detected using supervised learning techniques, which identify Mn and Sr concentrations, as well as Eu/Eu* ratios and lambda values as important discriminators. Igneous titanite compositions are influenced by both bulk magma chemistry and late-stage residual melt chemistry, with important implications for false positives when applying conventional techniques to mineral prospectivity studies.
Determining trace element chemistry and U-Pb isotopic compositions in both igneous and non-igneous titanite reveal the potential in recognising the presence of multiple titanite populations in the same rock. This is recommended as a means to identify porphyry titanite, allowing U-Pb ages to be related to mineralising events of a particular age. Overall, this study highlights the potential utility of titanite as an indicator mineral in porphyry copper systems.
Version
Open Access
Date Issued
2023-03-31
Date Awarded
01/02/2024
License URL
Advisor
Wilkinson, Jamie
Loader, Matthew
Pacey, Adam
Sponsor
Rio Tinto PLC
Grant Number
NE/P009794/1
Publisher Department
Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)