RB 2014/00003 Geology and mineral resources of Bimbowrie Conservation Park – the MacDonald Corridor and adjacent parts of the Palaeo- to Mesoproterozoic basement.
Published: 01 Jan 2014 Created: 25 Nov 2024 Revised: 27 Nov 2024

Former sheep station ‘Bimbowrie’, situated in the Olary Ranges, South Australia, was purchased by the South Australian Government as a conservation park in 2004. It has had a long history of mining, mineral exploration and geoscientific...

Former sheep station ‘Bimbowrie’, situated in the Olary Ranges, South Australia, was purchased by the South Australian Government as a conservation park in 2004. It has had a long history of mining, mineral exploration and geoscientific investigation. With mineral exploration being allowed, the geology and mineral resources of this important area are being documented as part of a wider programme of mapping the southern Curnamona Province. This first progress report summarises the geology and known mineral resources of the Macdonald Corridor, comprising Neoproterozoic metasediments, and adjacent parts of the Palaeo- to Mesoproterozoic Curnamona Province basement (Willyama Supergroup metasediments and Kalabity Supersuite and Ninnerie Supersuite igneous rocks). The late Palaeoproterozoic Willyama Supergroup comprises albitic, siliciclastic and minor calcareous metasedimentary rocks of the Curnamona Group. Felsic igneous rocks of the 1720–1710 Ma Basso Suite are interlayered with and intrusive into the Curnamona Group, which is disconformably overlain by base-metal-anomalous calc-silicate and psammite of the Bimba Formation, followed by the ~1693 Ma volcaniclastic Plumbago Formation and the pelite-dominated Raven Hill Subgroup. The ~1650 Ma Mount Howden Subgroup pelites and psammites at the top of the exposed Willyama Supergroup are found only north of the present map area, and are only briefly documented here. The Willyama Supergroup was deformed and metamorphosed to amphibolites facies under high-T/low-P conditions in the ~1600 Ma Olarian Orogeny. Early layer-parallel foliation was folded into isoclinal recumbent folds (nappes and nappe-thrusts) and later more upright folds. The overall transport direction was toward the northwest, and deformation was probably continuous and progressive. S-type granites of the Bimbowrie Suite were intruded late in the deformation history as part of the very widespread early Mesoproterozoic “Hiltaba event”. Late Olarian retrograde shear zones cut the metasediments and granites, and were responsible for major exhumation of the metamorphic complex, the deepest levels being exhumed in the south of the Curnamona Province. After a prolonged period of erosion, as part of the South Australian Craton, the Curnamona Province underwent extension and mafic dyke intrusion in the mid-Neoproterozoic. Further extension produced a series of southwestward-downstepping and northeastward-rotating fault blocks, the precursors of the present-day basement inliers. The Bimbowrie Inlier fault block was onlapped by the Belair Subgroup of the Burra Group, while the Kalabity Inlier to the northeast was elevated by the precursor of the Macdonald Fault. During the Sturt glaciation, glacial, fluvioglacial and glaciomarine diamictite, sandstone, siltstone, ironstone and conglomerate were deposited in the Macdonald Corridor, disconformably on the Belair Subgroup, while glacial topography was sculpted into the mountainous Kalabity Inlier block. In the later stages of the glaciation, sedimentation overstepped the Macdonald Fault onto the Kalabity Inlier, with massive granite conglomerate infilling a glacial U-shaped valley and interfingering with glaciomarine silts. The Braemar ironstone facies, a ferruginous siltstone (now metamorphosed and magnetite-bearing), developed in a shallow marine cold-water environment. During the ~500 Ma Delamerian Orogeny, the Macdonald Fault underwent reactivation as a dextral oblique-slip fault, accompanied by folding of the tilted Neoproterozoic sediments which were metamorphosed to upper greenschist facies. Regional ENE-trending fold axes were dragged into parallelism with the fault. Several late Olarian shear zones were reactivated and parts of the basement complex were rotated. Mineralisation in the present map area includes synsedimentary base-metal accumulations in the Bimba Formation, while the presence of quartz-Mn garnet rocks (coticule) and manganiferous BIF in the Broken Hill Group - equivalent Raven Hill Subgroup suggests potential for Broken Hill-type deposits where thicker successions may be preserved to the north of the present map area. Also to the north there is potential for IOCG-related copper, gold and uranium mineralisation where Bimbowrie Suite granites have not been as deeply eroded. Structurally controlled small copper deposits are widespread in fractures and shears, and the ultimate source of metal may be associated felsic volcanic rocks. Barite formed as a sedimentary exhalative deposit within the Cathedral Rock Formation. Pegmatite and coarsely crystalline albite bodies have been mined intermittently as a source for feldspar. Mafic dykes of presumed mid-Neoproterozoic age are also a local copper source, a sheared variety of one dyke being host for the Pimponda mine. The magnetite-rich Braemar ironstone facies of the Benda Siltstone has been a target of recent iron ore exploration.

More +

About this record

Record No d20010685
Topic Geoscientific Information
Type of Resource Document
Category Type
Document Type Departmental Publication - Geological Survey Geoscience Publication
Contributor DMITRE Mineral Resources Div., Geological Survey of South Australia;Mason Geoscience Pty Ltd
Sponsor
Tenement
Tenement Holder
Operator
Geological Province Curnamona Province
Mine Name Walter Outalpa mine
Stratigraphy
Commodity zircon
Notes
Geographic Locality: Olary Ranges;Bimbowrie Conservation Park;Macdonald [Structural] Corridor;Mount Mulga Nappe Syncline;Old Boolcoomata Homestead ruins;Cathedral Rock
Doc No: RB 2014/00003

Geographic Locality: Olary Ranges;Bimbowrie Conservation Park;Macdonald [Structural] Corridor;Mount Mulga Nappe Syncline;Old Boolcoomata Homestead ruins;Cathedral Rock Doc No: RB 2014/00003

Language English
Metadata Standard ISO 19115-3

Citations

Use constraints License
License Creative Commons Attribution 4.0
Persistent identifier https://pid.sarig.sa.gov.au/document/d20010685
Citation Preiss, W.V. 2014. RB 2014/00003 Geology and mineral resources of Bimbowrie Conservation Park – the MacDonald Corridor and adjacent parts of the Palaeo- to Mesoproterozoic basement. Departmental Publication - Geological Survey Geoscience Publication. Government of South Australia.
https://pid.sarig.sa.gov.au/document/d20010685

Technical information

Status
Maintenance and Update Frequency
Geographic Reference GDA2020 (EPSG:7844)
Geo bounding box {"type":"Polygon","coordinates":[[[140,-32.5],[140.5,-32.5],[140.5,-32],[140,-32],[140,-32.5]]]}
Purpose

                    
                    

                    
                  
Lineage