The Karoo Supergroup revisited and Madagascar-Africa fits

Abstract

New palæomagnetic data from the Late Permian-Early Jurassic Sakamena and the Late Carboniferous(?)-Early Permian Sakoa Group from Madagascar (Karoo Supergroup) show gross similarities with earlier published data. Palæomagnetic poles based on all studies of the Sakamena and Sakoa Groups average to 76.7°N and 290.8°E, and 51.3°N and 252.6°E, respectively, and imply palæoaltitudes of 28°S and 55°S for southwest Madagascar in Late Permian-Early Triassic and Late Carboniferous(?)-Early Permian times. The majority of the data, however, are of relatively poor quality and there is no firm evidence for primary magnetic signatures. A comparison with West Gondwana palæomagnetic poles shows that the Lottes and Rowley fit produces the best palæomagnetic match between Madagascar and East Africa (Somalia). The precise Pangæa configuration is still not known, but taken at face value, the Madagascar Sakamena pole and West Gondwana reference data indicate a Pangæa B or C configuration in Late Permian-Early Triassic times. However, high quality West Gondwana poles from Late Permian-Early Triassic times are clearly absent, and there is stronger confidence in West Gondwana poles of Late Carboniferous-Early Permian age. The latter poles place parts of Gondwana at high southerly latitudes and in good agreement with the distribution of climatically sensitive lithological data.