1
This project focuses on understanding the Paleoproterozoic Bryah and Padbury Basins through the interpretation of geophysical and geological datasets, aiming to better understand the basins’ history and geological features, including architecture, magmatism, sedimentary fill, and structural development, as well as the mineralization controls. www.cet.edu.au Stratigraphy and Architecture of the Paleoproterozoic Bryah and Padbury Basins, Capricorn Orogen: Towards an Understanding of Basin Evolution Lara Ramos , Alan Aitken, Sandra Occhipinti, Mark Lindsay CET-Centre for Exploration Targeting – The University of Western Australia Thanks to Sandfire Resources and Metals X for allowing the drill core analysis at the DeGrussa and Fortnum Mines, respectively, and for providing the samples for the petrophysical studies. The first author thanks the CNPq-Brazilian Counsel of Technological and Scientific Development for her scholarship, and thanks the Distal Footprints of Giant Ore System – UNCOVER Australia (RP04-063) for project funding. [email protected] The Bryah Basin was formed in a rift setting along the north margin of the Yilgarn Craton and contains volcano-sedimentary rocks of the Bryah Group (c. 2018 Ma). The Padbury Basin comprises carbonate, siliciclastic and banded iron formation rocks of the Padbury Group (2000-1800 Ma) deposited over the Bryah Group in a pro-foreland basin that developed during the Glenburgh Orogeny (2005-1960 Ma) Lower Bryah Group Padbury Group Bryah Group a. b. c. Petrophysical data from the Bryah and Padbury Basins and the surrounding terranes: a. summary of rock density plotted on a stratigraphic column of the Bryah and Padbury Basins, and the surrounding basement; b. magnetic susceptibility data; c. Box plot of the Bouguer Anomaly values of the Bryah and Padbury Basins’ units. Bouguer anomaly over the TDR gravity image, with indications of major Boundaries based on seismic data (Korsch & Doublier, 2016) and preliminary gravity features interpretation. Note the relation of the VMS mineralization (e.g. DeGrussa Mine) with the limits of the high gravity domain coincident with large faults. Magnetic domains and preliminary magnetic structural interpretation defined based on the magnetic amplitude and frequency of the Bryah and Padbury Basins and surrounding terranes overlying the RTP image. a. Bouguer anomaly slice filtered according to the frequencies that indicate deep gravity sources (~12km) interpreted on the Power Spectrum (b). a. Sourcing Parameters Imaging (SPI) and Euler deconvolution (index S0) showing deeper magnetic signals related with the northern and southern limits of the Bryah Basin, b. Magnetic Power Spectrum indicating deeper magnetic sources at ca. 4.5km, close to the one indicated by the SPI (4.25km). B b a. Ternary Magnetic Image integrating 1DV, TDR and Theta Map that individually proved useful during interpretation. b. Geophysical structural interpretation over RTP image. c. Field validation mapping. a c Bryah Group Narracoota Fm. Karalundi Fm. ? BRDD001 BRDD002 BRDD003 Preliminary graphic logs of the Neptune Prospect. Lower Padbury Sequence stratigraphy column based on Martin (1998). ? DGDD347 DDH1-F1 DGDD404 RCD358 Bryah and Padbury Basins geological map (Occhipinti et al,2017) over RTP image, and the stratigraphic columns of drill holes from the Fortnum Mine (DDH1-F1), Horseshoe Lights (RCD358) and DeGrussa Mine (DGDD404 and DGDD3467). Narracoota Fm. Ravelstone Fm. Juderina Fm. Marymia Inlier Narracoota Fm. Wilthorpe Fm. b a
