Publication Date:
2022-05-26
Description:
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): B02401, doi:10.1029/2010JB007740.
Description:
Within the framework of the Southern African Magnetotelluric Experiment a focused study was undertaken to gain improved knowledge of the lithospheric geometries and structures of the westerly extension of the Zimbabwe craton (ZIM) into Botswana, with the overarching aim of increasing our understanding of southern African tectonics. The area of interest is located in northeastern Botswana, where Kalahari sands cover most of the geological terranes and very little is known about lithospheric structures and thicknesses. Some of the regional-scale terrane boundary locations, defined based on potential field data, are not sufficiently accurate for local-scale studies. Investigation of the NNW-SSE orientated, 600 km long ZIM line profile crossing the Zimbabwe craton, Magondi mobile belt, and Ghanzi-Chobe belt showed that the Zimbabwe craton is characterized by thick (∼220 km) resistive lithosphere, consistent with geochemical and geothermal estimates from kimberlite samples of the nearby Orapa and Letlhakane pipes (∼175 km west of the profile). The lithospheric mantle of the Ghanzi-Chobe belt is resistive, but its lithosphere is only about 180 km thick. At crustal depths a northward dipping boundary between the Ghanzi-Chobe and the Magondi belts is identified, and two middle to lower crustal conductors are discovered in the Magondi belt. The crustal terrane boundary between the Magondi and Ghanzi-Chobe belts is found to be located further to the north, and the southwestern boundary of the Zimbabwe craton might be further to the west, than previously inferred from the regional potential field data.
Description:
In addition to the funding
and logistical support provided by SAMTEX consortium members (Council
for Geoscience, Geological Surveys Botswana and Namibia, De Beers Group
Services, Rio Tinto Exploration, and BHP Billiton), this work was also supported
by research grants from National Science Foundation’s Continental
Dynamics program (USA, EAR‐0309584 and EAR‐0455242), the Department
of Science and Technology (South Africa), and Science Foundation
Ireland (Ireland, grant 05/RFP/GEO001).
Keywords:
Magnetotellurics
;
Zimbabwe craton
;
Lithospheric structures
;
Southern Africa
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
