Paleomagnetism and tectonic evolution of the Pan‐African Damara Belt, southern Africa

摘要: Paleomagnetic results are reported from the Nosib, Otavi, and Mulden groups of Damara Supergroup, a late Precambrian shelf sequence on southern margin Congo craton in Namibia. Three magnetizations were isolated Nosib group samples. In order decreasing blocking temperature they NQ1 (n = 6 sites, λ 28°N, ϕ 323°E, α95 15°), NQ2 7 51°S, 213°E, 12°), NQ3 13 samples, 09°N, 295°E, 13°). Overall precision all three upon tectonic correction suggests that predate Pan-African (650–450 Ma) folding. Two Otavi above stratigraphic sequence. The DC1 component possible prefolding age 4 52°S, 186°E, 35°) has been over-printed by DC2 magnetization 10 55°S, 044°E, 15°) probable postfolding age. A single pre-folding was overlying Group samples 12°S, 090°E, 16°). Together with previously published paleomagnetic data Africa, new showed no great relative movements have occurred between Kalahari cratons during interval tectonism belt (McElhinny McWilliams, 1977). Continental collision preceded large displacements closure wide ocean (e.g., Himalayan analog) is effectively ruled out for belt. We develop an alternative model consistent available geologic data, which invokes rifting, heating, stretching lithosphere underneath belt, followed delamination subcrustal lithosphere. Hot asthenospheric material rises to take place detached sinking lithospheric base, inducing subduction interstacking continental crust. much thickened crust partially melted at depth, intruded synorogenic postorogenic granites finally uplifted eroded its present level exposure. compatible plate tectonics development can be broadly compared modern marginal seas, exception not induced secondary convection downgoing slab. Possible causes rising mantle plumes or intracontinental distortion within pre-Damara African plate.