Examples from a new EM and electrical methods receiver system

Abstract

The SMARTem Electrical Methods Geophysical Receiver System has evolved during the last three years as a flexible new tool for TEM, IP and other electrical geophysical survey methods. This paper presents a brief description of that instrument and several examples of data collected recently in Australia. First prototyped in mid-1995, the SMARTem receiver is now increasingly used in mineral exploration and ore delineation geophysics. Based on a rugged PC with a familiar operating system and programmed in a high level language, its aim is to increase the value of the data obtained in electrical geophysical campaigns. In addition to carrying out geophysical tasks in a graphics-rich environment it functions as a digital storage oscilloscope and spectrum analyser. SMARTem has been used in fixed-loop, moving-loop, borehole (axial and 3-component) and underground surveys in both direct-trigger and crystal-synchronised modes. TEM data from Leinster and Kambalda in Western Australia illustrate the use being made of SMARTem in the exploration for nickel deposits in Western Australia. Data is typically collected in or around existing mine infrastructure where electrical interference from power grids and other sources is significant. Signal and data processing strategies have been developed and optimised to allow data of the desired quality to be collected at good rates of production. Software for automated acquisition and processing of 3-component borehole TEM data has been developed. At Honeymoon Well, Western Australia, SMARTem work has been carried out over the Wedgetail Deposit ? a popular site for tests of TEM instrumentation. Fixed-loop and movinp-loop, TEM data from the site is presented to illustrate this instrument's performance in the mapping of this very difficult geophysical target. Recently, SMARTem borehole TEM data has been collected at Mount Isa in the exploration for new deposits in the Deep Copper mine. This environment is especially difficult for TEM as a result of interference from underground equipment. Examples of data sets and processing results are presented.