Mapping the surface geomorphology of the Makgadikgadi Rift Zone (MRZ)

摘要

The Makgadikgadi basin and wider Middle Kalahari region of Botswana and beyond host landforms which have been attributed to Quaternary environmental change, including palaeolake level fluctuations and aeolian activity. Tectonic processes and landforms on the other hand, have mostly been linked to the Okavango graben and associated rift zone (ORZ) to the west of the Makgadikgadi. In this paper we establish the extent of tectonic surface expression associated with the Makgadikgadi Rift Zone (MRZ). We identify a series of parallel, NNE-SSW, normal faults and scarps, expressing horst and graben structures linked to seven major blocks in the northern Makgadikgadi basin, using both Shuttle Radar Topographic Mission (SRTM) and geomagnetic data. Subtle expression of rifting has controlled endorheic drainage topology, replicated regional dune-field patterns and displaced the 945 m palaoelake contour since lake desiccation. These observations underscore the role of neotectonic "piano key" block movement in shaping surface landforms across a large expanse of the Kalahari region. This paper provides the first detailed map and introduction to the Makgadikgadi Rift Zone (MRZ) and its geomorphology. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.