... to future development in the area, including the establishment of commercial ranching beyond the main centres of settlement. Although groundwater in the Ecca aquifer in this area was known to be saline, reports persisted that better quality groundwater, perhaps suitable for agriculture, existed...

... mainly in semiconfined conditions; the Dwyka diamictites and tillites are fractured aquifers characterised by low borehole yields, ranging from 0.1 to 3.2 l/s and with K and T values of 0.8 m/day and 1.3 m 2 /day, respectively; the Vryheid Formation of the Ecca Group, which is a fractured aquifer...

.... The Ecca Group mainly consists of shales and mudstones and no major aquifer system is found within this layer. High yielding boreholes (>5 l/s) in the Ecca Group are usually associated with intrusive structures of a much younger age, with bedding plane fractures within sedimentary layers of the Ecca...

...- and Waterford formations of the Ecca Group and the Koonap Formation of the Beaufort Group as intersected by this ~2 352 m deep research borehole drilled in the southeastern sector of the basin. The weighted mean ages for the youngest zircons calculated for the formations of the Ecca- and Beaufort groups...

... of methane is produced by microbial processes. The presence of thermogenic methane together with helium on the surface is likely to give clues to pathways from depth. Exploration for shale gas in the deep Ecca will need to include isotope analysis for any contemplated baseline study. Editorial handling...

... sufficiently massive nor continuous to be detected separately in sounding curves. Exceptions are a few, thick, massive arenaceous turbidite fans occurring under an appreciable cover in the downwarped Karoo Trough, straddling the Lower Beaufort and Upper Ecca Subgroups at the southern extremity of the basin...

... Meandering rivers Lower Beaufort Adelaide Subgroup: Southwestern Karoo Southeastern Karoo Teekloof Balfour Meandering rivers Abrahamskraal Middleton Koonap Upper Ecca Waterford Delta front sands Fort Brown Prodelta slope muds Southwestern Karoo...

... by a shallow weathered-fractured rock aquifer comprising of the glacial and deltaic sediments of the Karoo Supergroup, while the deeper historically confined fractured bedrock aquifer consists predominantly of quartzite with subordinate lava, shale and conglomerate of the Witwatersrand Supergroup. The deep...

... in close proximity to the Whitehill Formation, which is the main target for shale gas exploration. This suggests that gas vents in the eastern Karoo Basin close to Lesotho are due to the release of gas from the carbonaceous shales of the Ecca Group. This is similar to breccia pipes mapped on surface...

...V. Nengovhela; B. Linol; L. Bezuidenhout; T. Dhansay; T Muedi; M.J. de Wit Abstract Contact metamorphism along widespread dolerite sills and dykes, emplaced at 182 to 183 Ma through the sedimentary host rocks of the Karoo Basin, triggered devolatilization of carbon-rich shales of the Lower Ecca...

...H. Mosavel; D.I. Cole; A.M. Siad Abstract Recent investigations of the shale gas potential in the main Karoo Basin have concentrated on the Whitehill Formation within the Ecca Group. This study focuses on the shale gas potential of the underlying Prince Albert Formation using the parameters...

... Karoo dolerite sill(s) would have represented distinct aquifers. The sandy diamictites and sandy esker deposits within the lower Dwyka would also represented aquifers, whereas the Ecca, Dwyka, and Nama shales in turn were rather impermeable and thus poor aquifers. Updoming during laccolith growth...

.... The Ecca Group is predominantly mudstone and shale, with subordinate sandstone and siltstone. It reaches a maximum thickness of 3 000 m. The lower part of the Ecca Group hosts most of the Karoo’s economic coal deposits and black carbonaceous mudstones are present. The Beaufort Group is the most widespread...

... glaciogenic diamictites and conglomerates and the overlying Ecca Group ( Johnson et al., 2006 ). The latter is represented by the Vryheid Formation mudrock, siltstone, sandstone, minor conglomerate and up to six coal seams. To the north of the Karoo Supergroup lithologies, the northern edge of the Karoo...

..., homogeneous shales with a high degree of anisotropy. The thick dolerite-rich middle zone 2 extending from the Upper Ecca Subgroup through the Beaufort Group and partially into higher Formations is characterised by the occurrence of large basin structures of dolerite. A model, which assumes a central dyke...

... of estimating peak temperatures. Our results indicate a regional elevation of palaeotemperatures of the organic-rich sedimentary rocks of the Ecca Group to temperatures where hydrocarbons are normally converted into gas. This study shows that the greatest thermal effects of the sill intrusions...

...T. Smithard; E.M. Bordy; D. Reid Abstract Recent interest in the shale gas potential in the main Karoo Basin of South Africa has focused attention mainly on the carbonaceous Whitehill Formation (Ecca Group, Karoo Supergroup). To unravel the metamorphic effect of the Lower Jurassic Karoo igneous...

...R.C. Minnaar; M.A. Dippenaar Abstract Faults and dolerite dykes within Basement- and Karoo-aquifers in northern Mozambique may increase groundwater occurrence but may also be barriers to groundwater flow. Should observation boreholes drilled into regional and local faults as well as dykes show...

...-topography of the Archaean and Paleoproterozoic basement and commonly pinch out against basement highs. The overlying Ecca Group comprises the Vryheid Formation, a deltaic and near-shore sequence marked by up to five coal seams separated by about 20 m of sand- and siltstone layers ( Cairncross, 1989...

...G. Mahed Abstract An aquifer in the semi-arid environment of Sutherland, South Africa is examined. The characterization of the saturated geological unit was completed by mapping associated dolerite dykes and fractured outcrops of Beaufort Group sedimentary rocks. This was complimented by pumping...