Data

Inferred Magnesium Number Maps for the Bulk Lithospheric Mantle Beneath Australia

Name: Inferred Magnesium Number Maps for the Bulk Lithospheric Mantle Beneath Australia
Published: 2023

Geoscience Australia

Haynes, M. ; Afonso, J.C.

ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rfr_id=info%3Asid%2FANDS&rft_id=https://pid.geoscience.gov.au/dataset/ga/149092&rft.title=Inferred Magnesium Number Maps for the Bulk Lithospheric Mantle Beneath Australia&rft.identifier=https://pid.geoscience.gov.au/dataset/ga/149092&rft.publisher=Commonwealth of Australia (Geoscience Australia)&rft.description=Raster datasets of inferred magnesium number for the bulk lithospheric mantle across the Australian continent. The magnesium number is an elemental ratio, defined by Mg / (Mg + Fe), which correlates to the relative enrichment or depletion in incompatible elements. Oxide concentrations are inferred in from thermo-chemical inverse modelling of Rayleigh phase velocities, surface heat flow, geoid anomalies, and topography. The magnesium number rasters summarise the results of a Markov-chain Monte Carlo sampling of the posterior model space from an ensemble of plausible candidate models. Model release 'FR23' is developed using primary-mode Rayleigh phase velocity grids adapted from Fishwick & Rawlinson (2012; 3-D structure of the Australian lithosphere from evolving seismic datasets). Model release 'KY22' is developed using the primary-mode Rayleigh phase velocity grids of Yoshizawa (2014; Radially anisotropic 3-D shear wave structure of the Australian lithosphere and asthenosphere from multi-mode surface waves). All models are products of the Exploring for the Future program.Maintenance and Update Frequency: notPlannedStatement: The inversion is based on Markov chain Monte Carlo sampling of major oxide compositions within the lithospheric mantle (Al2O3, CaO, FeO, and MgO). Coupled with temperature and pressure profiles, Gibbs free-energy minimisation (e.g. Connolly, 2009) allows estimation of the dominant mineral phases and, subsequently, the forward physical response. The LitMod inversion platform was used to perform a joint inversion of the following observed data: elevation (Whiteway, 2009), Rayleigh-wave phase velocities (Fishwick & Rawlinson, 2012; Yoshizawa, 2014), surface heat flow (International Heat Flow Commission, 2021), and long-wavelength geoid anomalies (Afonso et al., 2019). The parameterisation consists of 1D vertical columns across the Australian continent, with 1° lateral grid. The crust was divided into three layers: sediments, upper crust and lower crust. As a starting model, the thicknesses of sedimentary sequences were estimated using the Phanerozoic OZ SEEBASE dataset (Frogtech, 2005), and crustal thicknesses were taken from AusMoho2012 (Salmon et al., 2013). Similarly, the lower crust was assumed to comprise half the total crustal thickness, to a maximum of 15 km. Seismic wave speeds and density within the crust were initially set from AuSREM (Salmon et al., 2012). To help ensure that deep mantle structures are not mapped into the lithospheric mantle, we use the GyPSuM reference model (Simmons et al., 2010) to assign lower mantle seismic wave speed and density profiles. The magnesium number maps report an elemental ratio which can be calculated from the published LitMod results according to MgO/40.304 * (MgO/40.304 + FeO/71.844)^(-1).&rft.creator=Haynes, M. &rft.creator=Afonso, J.C. &rft.date=2023&rft.coverage=westlimit=155; southlimit=-46; eastlimit=111; northlimit=-9; projection=WGS 84 / geographic 2D (EPSG: 4326)&rft.coverage=westlimit=155; southlimit=-46; eastlimit=111; northlimit=-9; projection=WGS 84 / geographic 2D (EPSG: 4326)&rft_rights= https://creativecommons.org/licenses/by/4.0/&rft_rights=Creative Commons Attribution 4.0 International Licence&rft_rights=CC-BY&rft_rights=4.0&rft_rights=Any&rft_rights=Any&rft_rights=© Commonwealth of Australia (Geoscience Australia) & Macquarie University 2023&rft_rights=Australian Government Security Classification System&rft_rights=https://www.protectivesecurity.gov.au/Pages/default.aspx&rft_rights=WWW:LINK-1.0-http--link&rft_rights=Australian Government Security Classification System&rft_rights=Creative Commons Attribution 4.0 International Licence http://creativecommons.org/licenses/by/4.0&rft_subject=geoscientificInformation&rft_subject=EFTF – Exploring for the Future&rft_subject=Australia’s Resources Framework&rft_subject=Lithospheric Geophysics&rft_subject=LitMod&rft_subject=Magnesium number&rft_subject=Metasomatism&rft_subject=SCLM&rft_subject=Sub-Continental Lithospheric Mantle&rft_subject=Peridotite&rft_subject=Igneous and metamorphic petrology&rft_subject=Resource geoscience&rft_subject=Seismology and seismic exploration&rft_subject=Published_External&rft.type=dataset&rft.language=English Access the data

Cite Save to MyRDA

Licence & Rights:

Open Licence view details

Access:

Open

Brief description

Raster datasets of inferred magnesium number for the bulk lithospheric mantle across the Australian continent. The magnesium number is an elemental ratio, defined by Mg / (Mg + Fe), which correlates to the relative enrichment or depletion in incompatible elements. Oxide concentrations are inferred in from thermo-chemical inverse modelling of Rayleigh phase velocities, surface heat flow, geoid anomalies, and topography. The magnesium number rasters summarise the results of a Markov-chain Monte Carlo sampling of the posterior model space from an ensemble of plausible candidate models. Model release 'FR23' is developed using primary-mode Rayleigh phase velocity grids adapted from Fishwick & Rawlinson (2012; "3-D structure of the Australian lithosphere from evolving seismic datasets"). Model release 'KY22' is developed using the primary-mode Rayleigh phase velocity grids of Yoshizawa (2014; "Radially anisotropic 3-D shear wave structure of the Australian lithosphere and asthenosphere from multi-mode surface waves"). All models are products of the Exploring for the Future program.

Lineage

Maintenance and Update Frequency: notPlanned

Statement:

The inversion is based on Markov chain Monte Carlo sampling of major oxide compositions within the lithospheric mantle (Al2O3, CaO, FeO, and MgO). Coupled with temperature and pressure profiles, Gibbs free-energy minimisation (e.g. Connolly, 2009) allows estimation of the dominant mineral phases and, subsequently, the forward physical response. The LitMod inversion platform was used to perform a joint inversion of the following observed data: elevation (Whiteway, 2009), Rayleigh-wave phase velocities (Fishwick & Rawlinson, 2012; Yoshizawa, 2014), surface heat flow (International Heat Flow Commission, 2021), and long-wavelength geoid anomalies (Afonso et al., 2019). The parameterisation consists of 1D vertical columns across the Australian continent, with 1° lateral grid. The crust was divided into three layers: sediments, upper crust and lower crust. As a starting model, the thicknesses of sedimentary sequences were estimated using the Phanerozoic OZ SEEBASE dataset (Frogtech, 2005), and crustal thicknesses were taken from AusMoho2012 (Salmon et al., 2013). Similarly, the lower crust was assumed to comprise half the total crustal thickness, to a maximum of 15 km. Seismic wave speeds and density within the crust were initially set from AuSREM (Salmon et al., 2012). To help ensure that deep mantle structures are not mapped into the lithospheric mantle, we use the GyPSuM reference model (Simmons et al., 2010) to assign lower mantle seismic wave speed and density profiles. The magnesium number maps report an elemental ratio which can be calculated from the published LitMod results according to MgO/40.304 * (MgO/40.304 + FeO/71.844)^(-1).

Notes

Purpose
Maps of inferred magnesium number for the bulk sub-continental lithospheric mantle across Australia. The magnesium number is an elemental ratio, defined by Mg / (Mg + Fe), which correlates to the relative enrichment or depletion in incompatible elements. Oxide concentrations are inferred in these models from inverse modelling of Rayleigh phase velocities, surface heat flow, geoid anomalies, and topography. The inversions assume peridotite lithologies within the lithospheric mantle.

Created: 25 11 2023

Issued: 29 11 2023

Click to explore relationships graph

text: westlimit=155; southlimit=-46; eastlimit=111; northlimit=-9; projection=WGS 84 / geographic 2D (EPSG: 4326)

Subjects

User Contributed Tags

Other Information

Download Maps (zip) [1.0 MB]

uri : https://d28rz98at9flks.cloudfront.net/149092/149092_00_0.ZIP External Link

Identifiers

DOI : 10.26186/149092
URI : pid.geoscience.gov.au/dataset/ga/149092
global : c4659ea2-fbc8-4045-821f-b8700a6494b4

Similar data you may be interested in: