ISSN:
1365-246X
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
Seven new palaeopole positions from southern Egypt and northern Sudan with ages ranging from Upper Proterozoic (720 Ma) to Uppermost Cretaceous are presented and discussed in the context of the apparent polar wander path (APWP) of Africa. Rockmagnetic studies were also performed to determine the carriers of magnetization and to test the reliability of the remanence data. Ages pertinent to the APWP were taken from the literature or-for most of the localities-have been determined by K-Ar dating on whole rocks or minerals. the localities, geographic coordinates, ages, rock types and positions of the palaeomagnetic South Poles are as follows:(1) Gebel Gifata, SW Egypt, 29.0°E, 25.5°N, Upper Cretaceous (65–70 Ma) limestones and shales, 45.0°E, 81.5°S. (2) Northern Volcanic Field, N Sudan, 33.3°E, 19.0°N, Upper Cretaceous (80 Ma) basalts, 97.8°E, 55.9°S. (3) Nusab el Balgum complex, SW Egypt, 29.3°E, 23.3°N, Triassic (216 Ma) rhyolites and subvolcanics, 50.7°E, 64.1°S. (4) Sabaloka complex, N Sudan, 32.6°E, 16.3°N, Lower Devonian (395 Ma) volcanics, subvolcanics, metamorphosed quartzite, 55.8°E, 43.5°S. (5) Bir Safsaf, SW Egypt, 29.3°E, 23.1°N, Cambrian (586 Ma) dykes, 249.7°E, 80.0°N. (6) Nabati, N Sudan, 33.7°E, 18.1°N, Pre-Cambrian-Lower Cambrian (589 Ma) diorite and granite, 314.1°E, 67.9°N. (7) Kadaweb, Red Sea Hills, N Sudan, 36.3°E, 20.1°N, Proterozoic (720 Ma) gabbros, 319.6°E, 1.0°N.Nine other localities of Mesozotc and Palaeozoic rocks gave no reliable pole positions, mostly due to secondary magnetizations. the seven palaeopoles cover the Phanerozoic and Upper Proterozoic and increase the palaeomagnetic database for Africa. For the Phanerozoic there is coincidence with the palaeomagnetic data of other African cratonic areas indicating that Africa has behaved as a more or less stable block since the end of the Pan-African orogeny.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-246X.1989.tb00497.x
Permalink