Authors / CoAuthors
Condon, M.A. | Johnstone, D. | Perry, W.J. | Crespin, I.
Abstract
The Cape Range Structure, which occupies the North-West Cape peninsula, is a closed anticline in Tertiary limestones. The structure is at least eighty miles long and twenty miles wide, and has a vertical closure of 1200 feet and a closed area of 1200 square miles. The physiography is a reflection of the structure-a young fold mountain with mainly consequent, closely-spaced, drainage. The Tertiary sediments were laid down in a shelf area of the southwestern arm of the Indo-Pacific geosyncline. Because of the stability of the adjoining Western Australian shield, they did not attain the thickness of the sediments laid down elsewhere in the Indonesian geosyncline, nor were they affected to the same extent by subsequent tectonic disturbance. Five Tertiary formations are exposed on the Cape Range-the lower Miocene (e-stage) Mandu Calcarenite (265 feet of chalky limestone), the lower Miocene (f1-stage) Tulki Limestone (225 to 420 feet of hard crystalline limestone) and the possibly lower Miocene (f1 to , ?f2stage). Trealla Limestone (18'0 feet of white crystalline limestone), constituting the Cape Range Group; and the possibly lower Miocene Pilgramunna Formation and possibly Pliocene Vlaming Formation, forming the Yardie Group (calcareous sandstone and fine conglomerate up to 300 feet thick). Beneath the Miocene limestones are probably at least 3,000 feet of Cretaceous and Eocene marine sediments and possibly up to 18,000 feet of Permian, Carboniferous, and Devonian marine sediments. In vertical closure and closed area the Cape Range Structure is' the largest in the Carnarvon (North-West) Basin. Potential drainage of oil is unrestricted on the west flank and on the northern two-thirds of the east flank. Further geophysical (gravity and seismic) investigations should be carried out so as to try to determine the thickness of sediments and the shape of the structure in depth.
Product Type
document
eCat Id
221
Contact for the resource
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Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GA PublicationBulletin
- ( Theme )
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- geology
- ( Theme )
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- stratigraphy
- ( Theme )
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- structural geology
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- AU-WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1955-01-01T00:00:00
Creation Date
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unknown
Topic Category
geoscientificInformation
Series Information
Bulletin 021
Lineage
Unknown
Parent Information
Extents
[-23.0, -21.5, 113.5, 114.5]
Reference System
Spatial Resolution
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Source data not available.