RB 2015/00007 Coober Pedy Precious Stones Field 40Ar/39Ar geochronology of alunite and opal formation.

Published: 01 Apr 2015 Created: 25 Nov 2024 Revised: 27 Nov 2024

Author: Morris, B.J.

Precious opal in South Australia occurs near the base of the weathered profile developed in Early Cretaceous host marine clastic sediments. It is associated with the supergene minerals alunite, kaolinite, gypsum and iron oxides, that are variously seen to have formed within a variety of rock types where the profile has been protected from erosion by siliceous Cainozoic sediments. Radiometric 40Ar/39Ar dating of five alunite samples collected from three widely separated locations at the Coober Pedy Precious Stones Field gave ages ranging from 15.71 Ma to 12.37 Ma, and showed a younging in age with sample depth, a genetic factor which is considered to have followed the fall of ground water levels that occurred during the Late Tertiary. Precious opal is considered to have formed towards the end of the Miocene from the remobilisation of disseminated amorphous opal that may be as old as 60 Ma.

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About this record

Record No	d20011028
Topic	Geoscientific Information
Type of Resource	Document
Category Type	Earth Sciences Engineering Geochemistry Geochronology Geology Geomatic Engineering Geomorphology And Regolith And Landscape Evolution Geophysics Historical Geology Hydrogeology Isotope Geochemistry Marine Geoscience Mineral Exploration Mineral Resource Geology Mineral System Geology Mineralogy And Crystallography Mining Engineering Paleoclimatology Petrology Physical Geography Policy And Administration Primary Mining And Extraction Of Mineral Resources Quaternary Environments Radiometrics Sedimentology Soil Chemistry Soil Science Stratigraphy Surface Geology Surface Processes Surfacewater Hydrology Volcanology
Document Type	Departmental Publication - Geological Survey Geoscience Publication
Contributor	Geological Survey of South Australia;The University of Queensland
Sponsor	Coober Pedy Miners Association Inc.
Tenement
Tenement Holder
Operator
Geological Province	Eromanga Basin
Mine Name	Coober Pedy Precious Stones Field;Donnas Rush;Larkins Folly;Browns Folly
Stratigraphy	Bulldog Shale Russo Beds
Commodity	gemstone industrial material
Notes	Notes: Includes as an appendix: - Vasconcelos, P.M. and Thiede, D.S., 6/6/2014. Argon argon geochronology of selected rock samples from Coober Pedy (The University of Queensland commercial analytical contractors' report for the GSSA). 29 pages,... Notes: Includes as an appendix: - Vasconcelos, P.M. and Thiede, D.S., 6/6/2014. Argon argon geochronology of selected rock samples from Coober Pedy (The University of Queensland commercial analytical contractors' report for the GSSA). 29 pages, 1 appx, figures, tables. Geographic Locality: Coober Pedy Doc No: RB 2015/00007 More +
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/d20011028
Citation	Morris, B.J. 2015. RB 2015/00007 Coober Pedy Precious Stones Field 40Ar/39Ar geochronology of alunite and opal formation. Departmental Publication - Geological Survey Geoscience Publication. Government of South Australia. https://pid.sarig.sa.gov.au/document/d20011028

Technical information

Status
Maintenance and Update Frequency
Geographic Reference	GDA2020 (EPSG:7844)
Geo bounding box	{"type":"Polygon","coordinates":[[[133.5,-30],[135,-30],[135,-28],[133.5,-28],[133.5,-30]]]}
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Lineage