The Southern African Magnetotelluric Experiment (SAMTEX) images the underbelly of southern Africa
|Category||Tectonic & Seismotectonic|
|Location||International Geological Congress,oslo 2008|
|Author||Muller, Mark R.۱; Hamilton, Mark P.۱; Miensopust, Marion P.۱; Garcia, Xavier۱; Evans, Rob L.۲; Cole, Patrick۳; Ngwisanyi, Tiyapo۴; Hutchins, Dave۵; Fourie, Stoffel۶; Evans, Shane F.۷; Mountford, Andy۸; Pettit, Wayne۹; SAMTEX, MT Team۱|
|Holding Date||02 September 2008|
The Southern African Magnetotelluric Experiment (SAMTEX) is making electromagnetic measurements on a regional basis across Botswana, Namibia and South Africa. It is the largest EM experiment conducted, and, when comleted after Phase IV in April, 2008, will comprise deep (200+ km) EM probing into the Earth at over 750 locations across an area of over one million square kilometres. SAMTEX was initiated in 2003 with four partners (DIAS, WHOI, CGS and DeBeers) as a project based entirely in South Africa to provide EM complementary data to the Southern African Seismic Experiment. It has grown over its four phases and now has eleven partners in the consortium from academia (DIAS, WHOI, Wits), government (CGS, CSIR, GSB, GSN) and industry (ABB, BHP-Billiton, DeBeers, Rio Tinto) and measurements over most of Namibia and all of Botswana in addition to the South African ones.
Strong regional variations in electrical conductivity at crustal and lithospheric mantle level are readily apparent in images and models from the data. In particular, the cratonic regions (Kaapvaal, Zimbabwe and Angola cratons) are resistive for much of their lithospheric extent, whereas the stitching mobile belts are far more conductive. There is a strong correlation between the diamondiferous kimerlites and the locations of deep (200+ km) resistive regions, and of non-diamondiferous kimberlites with less-resistive deep lithosphere.
Other aspects, including correlations between electrical and seismic velocities, will be presented.