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Geology of the Acropolis prospect, South Australia, constrained by high-precision CA-TIMS ages

Citation

McPhie, J and Ehrig, KJ and Kamenetsky, MB and Crowley, JL and Kamenetsky, VS, Geology of the Acropolis prospect, South Australia, constrained by high-precision CA-TIMS ages, Australian Journal of Earth Sciences, 67, (5) pp. 699-716. ISSN 0812-0099 (2020) [Refereed Article]

Copyright Statement

Copyright 2020 Geological Society of Australia

DOI: doi:10.1080/08120099.2020.1717617

Abstract

Acropolis is an Fe-oxide–copper–gold prospect ∼20 km from Olympic Dam, South Australia, and marked by near-coincident gravity and magnetic anomalies. Prospective Fe-oxide–apatite ± sulfide veins occur in Mesoproterozoic and Paleoproterozoic volcanic and granitoid host units beneath unmineralised sedimentary formations. We have produced a geological map and history of the prospect using data from 16 diamond drill holes, including LA-ICPMS and high-precision CA-TIMS ages. The oldest unit is megacrystic granite of the Donington Suite (ca 1850 Ma). A non-conformity spanning ca 250 My separates the Donington Suite and felsic lavas and ignimbrites of the Gawler Range Volcanics (GRV; 1594.03 ± 0.68 Ma). The GRV were intruded by granite of the Hiltaba Suite (1594.88 ± 0.50 Ma) and felsic dykes (1593.88 ± 0.56 Ma; same age as the Roxby Downs Granite at Olympic Dam). The felsic dykes are weakly altered and lack Fe-oxide–apatite–sulfide veins, suggesting that they post-date the main hydrothermal event. If correct, this relationship implies that the main hydrothermal event at Acropolis was ca 1594 Ma and pre-dated the main hydrothermal event at Olympic Dam. The GRV at Acropolis are the same age as the GRV at Olympic Dam and ca 3–7 My older than the GRV exposed in the Gawler Ranges. The gravity and magnetic anomalies coincide with sections through the GRV, Hiltaba Suite and Donington Suite that contain abundant, wide, Fe-oxide veins. The GRV, Hiltaba Suite and Donington Suite are unconformably overlain by the Mesoproterozoic Pandurra Formation or Neoproterozoic Stuart Shelf sedimentary formations. The Pandurra Formation shows marked lateral variations in thickness related to paleotopography on the underlying units and post-Pandurra Formation pre-Neoproterozoic faults. The Stuart Shelf sedimentary formations have uniform thicknesses.

Item Details

Item Type:Refereed Article
Keywords:Acropolis prospect, Olympic Cu–Au–U province, CA-TIMS, geochronology, geophysical anomaly, Gawler Range, Volcanics, Hiltaba Suite, Mesoproterozoic,Olympic Dam, zircon U-Pb dating, IOCG, Gawler Craton
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and metamorphic petrology
Objective Division:Energy
Objective Group:Energy exploration
Objective Field:Uranium exploration
UTAS Author:McPhie, J (Professor Jocelyn McPhie)
UTAS Author:Kamenetsky, MB (Dr Maya Kamenetsky)
UTAS Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:143720
Year Published:2020
Funding Support:Australian Research Council (LP130100438)
Web of Science® Times Cited:3
Deposited By:CODES ARC
Deposited On:2021-03-30
Last Modified:2021-08-24
Downloads:0

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