Time constraints on Early Tonian Rifting and Cryogenian Arc terrane-continent convergence along the northern margin of the West African craton: Insights from SHRIMP and LA-ICP-MS zircon geochronology in the Pan-African Anti-Atlas belt (Morocco)

Revised stratigraphic framework for the lower Anti-Atlas Supergroup based on U–Pb geochronology of magmatic and detrital zircons (Zenaga and Bou Azzer-El Graara inliers, Anti-Atlas Belt, Morocco)

“…2060 Ma) and a minor Neoproterozoic one (with a prominent mode at ca. 690 Ma); the latter defines, along with the 697.3 ± 2.2 Ma maximum depositional age of the metasiltstone from the most basal part of the Bleida Formation (Bouougri et al, 2020), a Cryogenian maximum depositional age for this formation (although the minimum depositional age is younger than 883 Ma). These data imply a significant hiatus (697 to <883 Ma) in time of deposition between the Tachdamt and Bleida formations.…”

“…The present study is based on field observations and new U-Pb ages for igneous zircons from dolerite sill intruding carbonates from the lower Anti-Atlas Supergroup in the Zenaga Inlier and detrital zircon grains from four samples from the lower, middle, and upper parts of the lower Anti-Atlas Supergroup in the Zenaga and Bou Azzer El Graara inliers. We propose a new lithostratigraphy for the Proterorozoic lower Anti-Atlas Supergroup of the Anti-Atlas Belt based on a discussion of our data in combination with the previously published data (Abati et al, 2010;Walsh et al, 2012;Letsch, 2018;Bouougri et al, 2020) and constrain the provenance for the five, major unconformity-bounded packages of the supergroup.…”

“…Abati et al, 2010;Gärtner et al, 2013;2018). However, recent studies in the northern WAC (El Bahat et al, 2013;Söderlund et al, 2013;Youbi et al, 2013;Ikenne et al, 2017) Walsh et al, 2002;Gasquet et al, 2004;El Bahat et al, 2013;Kouyaté et al, 2013;Söderlund et al, 2013;Youbi et al, 2013;El Bahat et al, 2017;Ikenne et al, 2017;Bouougri et al, 2020 ;Youbi et al, 2020). Re-Os geochronology of the sedimentary succession of the Atar Group in the Taoudeni Basin of Mauritania indicated depositional ages ranging from 1109 ± 22 to 1105 ± 37 Ma (Rooney et al, 2010).…”

“…930 dates, consistent with ca. 883 Ma U-Pb SHRIMP zircon ages for two tuff horizons interbedded in the basal part of the Tachdamt Formation in the Siroua Inlier (Youbi et al, 2018, Bouougri et al, 2020. The youngest concordant zircon dates that overlap within errors in the sample BA24 from the Bleida Formation yield a concordia age of 1855 ± 6.5 Ma.…”

“…The NE30°-trending Iguerda-Taïfast mafic dyke swarm in the Zenaga and Iguerda-Taïfast inliers and the coeval volcanics of the Tachdamt Formation are part of the ca. 885-883 Ma Iguerda-Taïfast Large Igneous Province (LIP) in the Anti-Atlas Belt of Morocco (Kouyaté et al, 2013;Söderlund et al, 2013;Youbi et al, 2013Youbi et al, , 2018Bouougri et al, 2020), related to the rifting within the Rodinia supercontinent. The formation was likely deposited in the rift basin at the late stage in the assembly of the supercontinent Rodinia, but it remains uncertain whether this basin evolved into a passive continental margin setting along the northern margin of the WAC.…”