The Southern African Magnetotelluric Experiment (SAMTEX) images the underbelly of southern Africa

Alan G. Jones (alan@cp.dias.ie), Mark R. Muller (mark.muller@dias.ie), Mark P. Hamilton (mh@cp.dias.ie), Marion P. Miensopust (marion@cp.dias.ie), Xavier Garcia (xavi@cp.dias.ie)
Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2, Ireland

Rob L. Evans (revans@whoi.edu)
Woods Hole Oceanographic Institution, Department of Geology and Geophysics, Clark South 172, 360 Woods Hole Road, Woods Hole, Massachusetts, 02543-1542, U.S.A.

Patrick Cole (pcole@geoscience.org.za)
Council for Geoscience, 280 Pretoria Street, Silverton, Pretoria 0001, South Africa

Tiyapo Ngwisanyi (tngwisanyi@gov.bw)
Geological Survey of Botswana, Private Bag 14, Lobatse, Botswana

Dave Hutchins (dhutchins@mme.gov.na)
Geological Survey of Namibia, 1 Aviation Road, Windhoek, Namibia 

C.J.S. Fourie (sfourie@csir.co.za)
Council for Scientific and Industrial Research, Address 

Shane F. Evans (Shane.Evans@au.debeersgroup.com)
De Beers Group Services, Private Bag X01, Southdale 2135, South Africa

Andy Mountford (Andy.Mountford@riotinto.com)
Rio Tinto Mining and Exploration Ltd., PO Box 695, 7th Floor Castlemead, Lower Castle Street, Bristol BS99 1FS, U.K.

Wayne Pettit (Wayne.Pettit@bhpbilliton.com)
BHP Billiton, 6 Hollard Street, Johannesburg 2001, South Africa 

and the SAMTEX Team
Other members of the SAMTEX team are: Louise Collins, Colin Hogg, Clare Horan, Jessica Spratt, Gerry Wallace (Dublin Institute for Advanced Studies); Alan D. Chave (Woods Hole Oceanographic Institution); Janine Cole, Raimund Stettler (Council for Geoscience); Susan J. Webb (University of the Witwatersrand); G. Tshoso (Geological Survey of Botswana); Ed Cunion (Rio Tinto Mining and Exploration); David Khosa (BHP-Billiton)

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.