The Geological Survey of South Australia’s (GSSA) Gawler Challenge Phase 2: next generation mineral systems mapping (GP2) program allowed the authors of this report to revisits some ground-breaking landscape evolution studies with new geophysical...
The Geological Survey of South Australia’s (GSSA) Gawler Challenge Phase 2: next generation mineral systems mapping (GP2) program allowed the authors of this report to revisits some ground-breaking landscape evolution studies with new geophysical data and reprocessed remote sensing data in a region of high resource potential within South Australia. The study area, located in the central–western Gawler Craton of South Australia, comprises thin basin margin successions and paleovalleys. Three basins (Arckaringa, Eromanga and Eucla) contain nearshore to onshore coastal-channel sediments of late Paleozoic, Mesozoic and Cenozoic ages, linked to an extensive network of peripheral paleovalleys that drained the Precambrian Gawler Craton and Musgrave Province, as well as the Neoproterozoic – Early Paleozoic Officer Basin. Understanding the geology and sedimentary evolution of these basins and peripheral paleovalleys has relevance to the exploration for placer deposits (e.g., gold, heavy minerals), secondary geochemical deposits (e.g., uranium), clay minerals and for saline and rarely, potable groundwater resources in the basin and channel sediments. Knowledge of the basin and paleovalley architecture and any concentration of minerals in the channels is also of interest as guides to the location of both paleochannel and bedrock lode deposits in the Gawler Craton. Geoscientific datasets have been integrated in an investigation of these basins and peripheral paleovalleys that have significance for mineral exploration. The objective of the study was to understand the basin characteristics and history, and to map the paleo-components related to these basins and paleovalleys, in order to assist exploration in GP2 basin-paleodrainage terrains. This was achieved through the combination of results from various geographical, geological and particularly new geophysical datasets. These include interpretations drawn from field observations, a compendium of geological and drilling data, topographic and evaluated digital elevation models, remote sensing imagery, geophysical data (e.g. magnetics, gravity, airborne and transient electromagnetics and radiometrics, where available), all of which have contributed to a systematic investigation of the basin-paleodrainage terrains. Physical property contrasts that exist between the basin/channel sediments and the underlying bedrocks/basement, for instance, can be differentiated by geophysical methods to locate the basin framework and paleoshorelines/paleovalleys. Evidence from sedimentological records was combined with other geological, geomorphological and geophysical characteristics to arrive at a general reconstruction of basinal and paleovalley architectures and depositional environments.
More +