Reply to discussion on ‘From Pan-African transpression to Cadomian transtension at the West African margin: new U–Pb zircon ages from the Eastern Saghro Inlier (Anti-Atlas, Morocco)’ by Errami et al . ( SP 503, 209–233)

Abstract

The comment of Ikenne et al. concerns recently described U-Pb baddeleyite ages, around 1.71 and 1.65 Ga, obtained on intrusive sills and dykes in the Taghdout-Lkest Group in the SW domain of the Anti-Atlas (AA). These authors suggest an independent geodynamic evolution of the eastern and western domains of the Anti-Atlas prior to the Ediacaran period. Furthermore, they state that we do not take this magmatic event into account when interpreting our data. We like to emphasize that this is beyond the scope of our paper and does not affect our interpretation of the AA evolution during the deposition of the Ediacaran sedimentary successions (Saghro, Mgouna, and Ouarzazate goups). We agree with the comment that we did not distinguish the Taghdout-Lkest from the Bleida-Tachdamt groups and now we separate them in the revised figure 2. The different geodynamic evolution of the SW and NE Anti-Atlas domains in pre-Ediacaran times sensu Ikenne et al., is not consistent with abundant inherited Paleoproterozoic zircon detritus and Nd model ages (0.80-1.82 Ga) from the northeastern Anti-Atlas and the Meseta. There is no doubt about Late Paleoproterozoic baddeleyite ages, but they do not have an analogue in the zircon age record of the West African Craton, which is expected from ultramafic rocks with few zircon grains. However, they locally allow assuming a Late Paleoproterozoic deposition of the lower Taghdout-Lkest Group. Any age constraints for the upper parts of this group are lacking, thus allowing a hypothetic deposition between ca. 1.65 Ga and 0.83 Ga (the assumed age of initial Bleida-Tachdamt Group deposition). Therefore, it is very important to close the gap in detailed stratigraphic studies that would allow differentiating between the different Late Paleoproterozoic and Early Neoproterozoic events including the stratigraphic position of the upper Taghdout-Lkest Group and Bleida-Tachdamt group.

The Oumjrane-Boukerzia Mining District (Eastern Anti-Atlas, Morocco): Constraints of its geological and tectono-magmatic setting

“…(iii) The Post Pan-African domain (northeastern Anti-Atlas) is formed by the Upper Neoproterozoic series and consists mainly of the Saghro Group. This later is attributed to Late Cryogenian and Early Ediacaran time and is covered by the younger Bou Salda, Dadès and Mgouna groups [29]- [32].…”