Differentiating between hydrothermal and diagenetic carbonates using rare earth element and yttrium (REE+Y) geochemistry: A case study from the Paleoproterozoic George Fisher massive sulphide Zn deposit
Cite as:
Rieger, Philip; Magnall, Joseph M.; Gleeson, Sarah A.; Oelze, Marcus; Wilke, Franziska D.H.; Lilly, Richard (2021): Differentiating between hydrothermal and diagenetic carbonates using rare earth element and yttrium (REE+Y) geochemistry: A case study from the Paleoproterozoic George Fisher massive sulphide Zn deposit. GFZ Data Services. https://doi.org/10.5880/GFZ.3.1.2020.005
Status
I N R E V I E W : Rieger, Philip; Magnall, Joseph M.; Gleeson, Sarah A.; Oelze, Marcus; Wilke, Franziska D.H.; Lilly, Richard (2021): Differentiating between hydrothermal and diagenetic carbonates using rare earth element and yttrium (REE+Y) geochemistry: A case study from the Paleoproterozoic George Fisher massive sulphide Zn deposit. GFZ Data Services. https://doi.org/10.5880/GFZ.3.1.2020.005
Abstract
Carbonate minerals are ubiquitous in most sediment-hosted mineral deposits. These deposits can contain a variety of carbonate types with complex paragenetic relationships. When normalized to chondritic values (CN), rare-earth elements and yttrium (REE+YCN) can be used to constrain fluid chemistry and fluid-rock interaction processes in both low- and high-temperature settings. Unlike other phases (e.g., pyrite), the application of in situ laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) data to the differentiation of pre-ore and hydrothermal carbonates remains relatively untested. To assess the potential applicability of carbonate in situ REE+Y data, we combined transmitted light and cathodoluminescence (CL) petrography with LA-ICP-MS analysis of carbonate mineral phases from (1) the Proterozoic George Fisher clastic dominated (CD-type) massive sulfide deposit and from (2) correlative, barren host rock lithologies (Urquhart Shale Formation).
The REE+YCN composition of pre-ore calcite suggests it formed during diagenesis from diagenetic pore fluids derived from ferruginous, anoxic seawater. Hydrothermal and hydrothermally altered calcite and dolomite from George Fisher is generally more LREE depleted than the pre-ore calcite, whole-rock REE concentrations, and shale reference values. We suggest this is the result of hydrothermal alteration by saline Cl--rich mineralizing fluids.
Furthermore, the presence of both positive and negative Eu/Eu* values in calcite and dolomite indicates that the mineralizing fluids were relatively hot (>250°C) and cooled below 200-250°C during ore formation. This study confirms the hypothesis that in situ REE+Y data can be used to differentiate between pre-ore and hydrothermal carbonate and provide important constraints on the conditions of ore formation.
Authors
Rieger, Philip;GFZ German Research Centre for Geosciences, Potsdam, Germany;Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
Magnall, Joseph M.;GFZ German Research Centre for Geosciences, Potsdam, Germany
Gleeson, Sarah A.;GFZ German Research Centre for Geosciences, Potsdam, Germany;Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
Oelze, Marcus;GFZ German Research Centre for Geosciences, Potsdam, Germany
affiliation (affiliationIdentifier=0000-0001-7888-0077 affiliationIdentifierScheme=ORCID): GFZ German Research Centre for Geosciences, Potsdam, Germany
affiliation: Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
creator
creatorName (nameType=Personal): Magnall, Joseph M.
affiliation (affiliationIdentifier=0000-0002-7868-3038 affiliationIdentifierScheme=ORCID): GFZ German Research Centre for Geosciences, Potsdam, Germany
creator
creatorName (nameType=Personal): Gleeson, Sarah A.
affiliation (affiliationIdentifier=0000-0002-5314-4281 affiliationIdentifierScheme=ORCID): GFZ German Research Centre for Geosciences, Potsdam, Germany
affiliation: Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
affiliation (affiliationIdentifier=0000-0002-3950-6629 affiliationIdentifierScheme=ORCID): GFZ German Research Centre for Geosciences, Potsdam, Germany
affiliation (affiliationIdentifier=0000-0002-3463-6176 affiliationIdentifierScheme=ORCID): GFZ German Research Centre for Geosciences, Potsdam, Germany
affiliation: Department of Earth Sciences, University of Adelaide, Adelaide, Australia
titles
title: Differentiating between hydrothermal and diagenetic carbonates using rare earth element and yttrium (REE+Y) geochemistry: A case study from the Paleoproterozoic George Fisher massive sulphide Zn deposit
CharacterString: Differentiating between hydrothermal and diagenetic carbonates using rare earth element and yttrium (REE+Y) geochemistry: A case study from the Paleoproterozoic George Fisher massive sulphide Zn deposit
CharacterString: Carbonate minerals are ubiquitous in most sediment-hosted mineral deposits. These deposits can contain a variety of carbonate types with complex paragenetic relationships. When normalized to chondritic values (CN), rare-earth elements and yttrium (REE+YCN) can be used to constrain fluid chemistry and fluid-rock interaction processes in both low- and high-temperature settings. Unlike other phases (e.g., pyrite), the application of in situ laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) data to the differentiation of pre-ore and hydrothermal carbonates remains relatively untested. To assess the potential applicability of carbonate in situ REE+Y data, we combined transmitted light and cathodoluminescence (CL) petrography with LA-ICP-MS analysis of carbonate mineral phases from (1) the Proterozoic George Fisher clastic dominated (CD-type) massive sulfide deposit and from (2) correlative, barren host rock lithologies (Urquhart Shale Formation).
The REE+YCN composition of pre-ore calcite suggests it formed during diagenesis from diagenetic pore fluids derived from ferruginous, anoxic seawater. Hydrothermal and hydrothermally altered calcite and dolomite from George Fisher is generally more LREE depleted than the pre-ore calcite, whole-rock REE concentrations, and shale reference values. We suggest this is the result of hydrothermal alteration by saline Cl--rich mineralizing fluids.
Furthermore, the presence of both positive and negative Eu/Eu* values in calcite and dolomite indicates that the mineralizing fluids were relatively hot (>250°C) and cooled below 200-250°C during ore formation. This study confirms the hypothesis that in situ REE+Y data can be used to differentiate between pre-ore and hydrothermal carbonate and provide important constraints on the conditions of ore formation.
pointOfContact
CI_ResponsibleParty
individualName
CharacterString: Rieger, Philip
organisationName
CharacterString: GFZ German Research Centre for Geosciences, Potsdam, Germany
CI_OnLineFunctionCode (codeList=http://www.isotc211.org/2005/resources/Codelist/gmxCodelists.xml#CI_OnLineFunctionCode codeListValue=http://www.isotc211.org/2005/resources/Codelist/gmxCodelists.xml#CI_OnLineFunctionCode_information): information