Frome Project (Curnamona Craton)
The Frome project area consists of 5 GELs
within an unexposed portion of the Mesoproterozoic Curnamona Craton
lying just south of Lake Frome in northeastern South Australia
(Figure 3). In this area the Curnamona Craton is covered by a
locally thick sequence of Neoproterozoic and Cambrian sediments
of the Moorowie Sub-basin, with a thinner cover of Mesozoic and
Tertiary sediments in places.
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Figure 3 - Gravity image (coloured) draped on aeromagnetic image,
showing location of GELs with respect to gravity low and interpreted
buried granitoid body
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On a global scale the Precambrian basement rocks in the exposed portion of the Curnamona Craton are relatively enriched in primary uranium, evidenced by numerous historic uranium deposits including Radium Hill, Crockers Well, Ethiudna and Mount Painter. Granitic rocks are widespread in this terrain and are frequently associated with zones of migmatisation indicating that the granitic magmas were probably formed by in situ partial melting of the country rocks during the peak of metamorphism.
The 1580 million year old Crockers Well granite lying immediately south of Geothermal Resources’ GELs, contains a distinctive highly radiogenic sodic granite phase. It forms discrete outcropping bodies up to several kilometres across and hosts widely scattered disseminated, fracture controlled and breccia hosted uranium–thorium mineralisation (Figure 3). The Crockers Well granite therefore constitutes a truly “hot” radiogenic granite capable of generating abnormally large amounts of heat.
Gravity data for the region shows a marked gravity low associated with the outcropping Crockers Well and related granites, which extends northwards under the Moorowie Sub-basin. According to PIRSA, depth to basement interpretations compiled from new seismic data, gravity data and borehole information, the Moorowie Sub-basin thickens rapidly northwards from the outcropping basement rocks, reaching depths of more than 8 kilometres in the central portion of the basin (Figure 4).
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Figure 4 - Geothermal Resources GELs in relation to buried granite and
depth to basement data
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Geothermal Resources’ GELs were pegged to cover the area of the gravity low and granite in the subsurface beneath the Moorowie Sub-basin. In this regard the general geological setting appears very analogous to the established Cooper Basin hot dry rock geothermal field.
A new seismic traverse line through the area confirms that the gravity low is almost certainly caused by granite in the subsurface and not by the thickened pile of sediments in the Moorowie Sub-basin (Figure 5). Over much of the area of the GELs the depth of the insulating sedimentary pile appears to approximate the ideal depth of 2-4 kilometres.
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Figure 5 - Seismic profile through Geothermal Resources GEL 210
Diffuse seismic responses in central section correspond with gravity low and are almost certainly caused by a large buried granitoid pluton. The Moorowie Sub-basin thickens towards the west.
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Figure 5a - Oblique view of seismic overlain by gravity map. Note the close correlaton between the gravity low and the interpreted granite position
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Figure 5b -Gravity contours over the Frome GEL
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Recently PIRSA awarded a PACE grant of $100,000 as a contribution to initial drilling at the Frome project, receipt of which by the Company, is contingent on the Company expending at least $100,000 on such drilling.
Other Exploration projects
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