Lateral termination of a delaminated orogenic root: Lower crustal architecture, and exhumation history of northern Mozambique

The East African-Antarctic Orogen forms one of the largest orogens on Earth and is characterized by strong lateral variations. The orogen root probably underwent partial delamination in its southern part, indicated by vast volumes of late-tectonic A-type granites between Mozambique and Antarctica. We identified a zone within the orogen, the Lurio Belt, that could represent the lower crustal expression of the boundary zone to the non-delaminated central and northern part of the orogen. Partly delaminated o rogen roots and especially the crustal expression of the boundary zone have thus far not been documented in any orogen. Different exhumation mechanisms and exhumation histories are expected on either side of such a boundary zone. The part of the orogen th at has a delaminated root will be relatively hot and will therefore undergo rapid mechanical thinning, associated with the development of metamorphic core complexes. The part of the orogen that has an intact root will be comparatively cold, less susceptib le to orogenic collapse and would remain as a high standing mountain belt undergoing relatively slow erosional unroofing. This project intends to test such a scenario in northern Mozambique by comparing the structure of the orogenic crust to the north and south of the Lurio Belt. We will use petrological and hermochronological methods on either side of the Lurio Belt to precisely date and quantify the exhumation histories and to gain crustal thickness informations. The project is the scientific follow up of an international effort to remap northern Mozambique as part of an infrastructure building program financed under the auspices of the World Bank and the Nordic Development Fund.