Paleomagnetic dating of continental geological formations: Strong diachronism evidenced in the Saharan platform and geodynamical implications

• Published in: Journal of African earth sciences (1994) Vol. 99; pp. 353 - 362
• Main Authors: Henry, B., Derder, M.E.M., Amenna, M., Maouche, S., Bayou, B., Ouabadi, A., Bouabdallah, H., Beddiaf, M., Ayache, M., Bestandji, R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-11-2014
• Subjects: Africa; Dating; Diachronism; Paleomagnetism; Permian; Diachronism; Permian; Dating; Paleomagnetism; Africa
• ISSN: 1464-343X; 1879-1956
• DOI: 10.1016/j.jafrearsci.2014.02.010

•Primary magnetization has been determined in a continental Saharan formation.•Dating has been made by comparison of these data with a known APWP.•Diachronism of at least 40My is evidenced within this formation.•Post-Hercynian structural evolution was not homogeneous in the Saharan platform.
The paleomagnetism is a powerful tool to date formations that have age not constrained by paleontological, stratigraphical or radiochronological data. It was applied, on the western border of the Murzuq basin in Algeria (Saharan platform), to the Zarzaïtine formation, attributed to a Middle–Upper Triassic–Lower Jurassic age. Comparison of the obtained paleomagnetic pole with previous poles from the same geological formation outcropping in another basin and from other Carboniferous to Lower Mesozoic African formations yielded a clearly older age (Late Permian) than expected. That evidences a strong diachronism (at least 40My) of the deposition of this formation on the Saharan platform. The post-Hercynian structural evolution was therefore different according to the parts of this platform, with significant differential vertical tectonic movements. The latter were at the origin of erosion, hiatus or sediments deposition according to areas.