COMPLEX MAGNETIZATION OF THE EARLY CAMBRIAN VOLCANO-SEDIMENTARY SEQUENCE FROM THE BOU-AZZER REGION, ANTI-ATLAS (MOROCCO)

The objective of this paper is to highlight the complexity of the magnetic record carried by the Early Cambrian volcano-sedimentary sequence from the Bou Azzer region in the Anti Atlas Mountains of Morocco. Despite an extensive sampling of various types of rocks with various bedding attitudes, the interpretation of the remanent directions in terms of successive paleomagnetic poles remains ambiguous. The comparison of these results with two paleomagnetic analyses previously carried out on the same sequence of rocks, sampled in the same region, does not clarify the interpretation. When all the results are considered together, some directions are easily explained either as a recent chemical remagnetization or as a Late Paleozoic (probably Permian) remagnetization. Other directions which are statistically similar to those used to define the Early Cambrian Bou Azzer pole, usually considered for the construction of the Apparent Polar Wander Path for Africa, can be interpreted either as a recent chemical remagnetization or as older magnetizations the timings of which are unknown but are unlikely to be Early Cambrian in age. Complementary rock magnetic analyses are needed to try to estimate the process, the chronology and possibly the periods of acquisition of these magnetizations. Finally, other directions of magnetization were identified in the Moroccan samples which are specific to a given locality and a given lithology. The meaning of these localized components is not clear (localized remagnetization process or artefact) but they are surely not representative of the sequence and therefore can not be used to constrain the movement of Africa, At this stage, we suggest that the results from the Bou Azzer sequence should not be used for the construction of the Paleozoic Apparent Polar Wander Path for Africa.