Sedimentary provenance of the Taza-Guercif Basin, South Rifean Corridor, Morocco: Implications for basin emergence

Abstract

The Taza-Guercif Basin is on the southern margin of the former Rifean Corridor, one of the major Miocene marine connections between the Atlantic Ocean and Mediterranean prior to the onset of the Messinian Salinity Crisis. As the first basin in the corridor to emerge during corridor closure, the basin is a key location for understanding this major marine event. To constrain the mechanisms for corridor closure, we contribute 499 zircon U-Pb crystallization ages and 98 zircon fission-track (ZFT) cooling ages from the stratigraphy of the Taza-Guercif Basin. The U-Pb age signature of the Taza-Guercif Basin is dominated by Pan-African (700–560 Ma) and West African craton (2200–1800 Ma) ages, and contains a significant abundance of Mesoproterozoic ages recently characterized in Mesozoic sediments from the Rif and Middle Atlas mountains. The ZFT ages record a significant Triassic-centered cooling population (275–150 Ma), well-defined Variscan (ca. 330 Ma) and post Pan-African (498 Ma) cooling peaks, and a scattering of Precambrian cooling ages. The cooling ages suggest a source in the Middle Atlas; this is consistent with the U-Pb crystallization ages. Furthermore, there is no discernable change in either the U-Pb or ZFT populations during basin emergence. Together, these observations suggest that the Middle Atlas mountains were a consistent source of sediment to the Taza-Guercif Basin and played a significant role in the closure of the Taza-Guercif Basin and possibly the Rifean Corridor.