McArthur Basin architecture ? a new perspective from geophysics and GIS

Abstract

Interpretations of the gross geometry of the McArthur Basin from regional potential field data are presented as a 2.5-D component of a metallogenic geographic information system (GIS) developed for the region. The McArthur Group, host to the major HYC Pb?Zn deposit, is seen to extend well beyond its eastern limit of outcrop as defined by the Emu Fault. Units identified as prospective using lithological criteria encoded in the GIS contain all known stratiform base metal mineralisation. Such deposits are preferentially located on the periphery of the thickest accumulations of McArthur Group sedimentary rocks. Volcanism in the upper and lower Tawallah Group is much more voluminous than its comparatively small stratigraphic thickness measured in outcrop would suggest. Over 15 km of basin fill (including volcanic rocks) is implied in some areas, but this may vary rapidly, implying considerable pre-McArthur Group structural development. A number of lineaments visible in the isochore images converge at the position of HYC, indicating bounding fault and strike-slip fault activity at this location during a large portion of basin evolution. These structures do not necessarily correspond to major regional faults interpreted from surface mapping.