Crower Project (South East SA)
The Crower project area consists of 4 GELs and 2 GELAs
that are located on the northern onshore margin of the Otway Basin
in southeastern South Australia (Figure 6). The Otway Basin is
a Jurassic to Cretaceous basin with Tertiary cover that was formed
along the southern coast of Australia as a result of rifting between
the Australian and Antarctic plates at the time of break up of
Gondwana.
The northern margin of the Otway Basin in South Australia is defined by outcropping granites of the Padthaway Ridge, which is the surface expression of the early Palaeozoic Kanmantoo Fold Belt in this area. Gravity and magnetic data, as well as drillhole information, indicates that several large granite bodies of the Padthaway Ridge extend beneath the northern Otway Basin within the Crower project area (Figure 6). It is these granite bodies that are candidates for hot dry rock geothermal energy sources when buried at sufficient depth beneath the Otway Basin sediments.
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Figure 6 - Geothermal Resources tenements with respect to depth
to
basement in northern Otway Basin
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The northern Otway Basin is marked by rapid changes in thickness of sediments caused by two half grabens now represented by the ENE-WSW trending Robe Trough and the SE-NW trending Penola Trough and adjacent
basement highs (Figure 7). More than 7000 metres of sediments are present in the deepest parts of these troughs, which are extremely narrow, elongate features presumably produced by the complex interaction of N-S to NNW-SSE basement faulting and rifting at the time of continental break up. The result is that within the project area the Palaeozoic granites of the Kanmantoo Fold Belt are buried over a wide range of depths, which gives the opportunity for selecting particular locations where interpreted burial depths are optimal for generating the required temperatures for a geothermal energy source.
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Figure 7 - SEEBASE image of depth to basement in Otway Basin,
showing location of Geothermal Resources GELAs
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A very significant feature of this region of South Australia is the higher heat flows shown on the heat flow map of Australia (Figure 2). The reason for the high heat flow is not certain, but it could relate to the complex rifting history of this area, with associated significant uplift and down drop of major crustal blocks. The abundant granite and volcanic rocks of the Kanmantoo Fold Belt, which form a significant part of the basement in this region, may have also been an important contributor of radiogenic heat. From a geothermal energy exploration perspective, this aspect is a major positive because it implies elevated geothermal gradients and the possibility of high temperatures in hot dry rocks at comparatively shallow, readily exploitable depths.
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Figure 2 - Heat flow map of Australia
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Other Exploration projects
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