A ~ 604 MA DEPOSITIONAL AGE FOR THE TIDDILINE CONGLOMERATE, BOU AZZER INLIER, MOROCCO BASED ON U-PB DATING OF DETRITAL ZIRCON
To address this debate, U-Pb ages of detrital zircon crystals were determined using the UCLA CAMECA 1270 ion microprobe. Folded beds of the Tiddiline conglomerate collected east of Ait Ahmane (Bou Azzer) in the Northern Tiddiline Basin (N30o 25.083396’, W 6o 28.187513’) of Bou Azzer contain detrital zircon yielding an age of 604 +/- 18 Ma, suggesting correlation with the Bou Salda Group rocks exposed in adjacent erosional inliers.
Quartz phyric volcanic rocks (N 30o31.476474’, W 6o 42.234728’) exposed in the northern Tiddiline basin and historically associated with the Tiddiline Formation, have been dated at 639 +/- 24 Ma. Rather than related to the late orogenic clastic basin deposits, the quartz phyric volcanic rocks are now recognized as being synchronous with the adjacent synorogenic Ousdrat quartz diorite intrusion (640.8 +/- 1.4 Ma). Available geochronologic evidence suggests that the Tiddiline Formation developed in the waning stages of a Pan African collision between a volcanic arc terrane and the West African craton ~585-620 Ma, in the aftermath of subduction generated arc magmatism and metamorphism ~640-650 Ma. This collision marked the final assembly stage of the Western Gondwana Supercontinent.