The resistivity structure of the Gidyea Suture and its relationship to the Carpentaria Conductivity Anomaly

The Gidyea Suture is a structure that lies on the eastern margin of the Mount Isa Province. It was first recognised in deep crustal seismic, and subsequent authors have used magnetotelluric (MT) data to further support its existence. It is considered to be a highly conductive zone that is part of the broad scale Carpentaria Conductivity Anomaly (CCA). New, high resolution MT data in the Cloncurry region, together with a more detailed interpretation of the location of the Gidyea Suture from the deep crustal seismic data provides additional constraint on the conductivity structure of the Gidyea Suture. The crustal conductivity feature typically attributed to the Gidyea Suture varies considerably along strike. The conductivity feature typically sits in the Numil terrain, which underlays the suture to the east and extends into the upper crust. In contrast, to the west of the Suture in the Cloncurry area, there is a resistive upper crust and a broad region of conductive lower crust that is largely confined between the Suture and Quamby Fault. A significant conductivity feature was also imaged in the mid to upper crust along the Quamby Fault. This feature may be associated with upper crustal graphitic shale basins or alteration along the fault. All these different conductive structures are within the zone typically considered to be the CCA. The complex and variable nature of resistivity structures along and around the Gidyea Suture indicates it cannot simply be thought of as an anomaly created by the Suture.