Research Paper GEOSPHERE Sedimentary provenance of the Taza-Guercif Basin, South Rifean Corridor, Morocco: Implications for basin emergence GEOSPHERE; v. 12, no. 1 Jonathan R. Pratt1, David L. Barbeau, Jr.1, Tyler M. Izykowski1, John I. Garver2, and Anas Emran3 1Department of Earth and Ocean Sciences, University of South Carolina, 710 Sumter Street, Columbia, South Carolina 29208, USA doi:10.1130/GES01192.1 2Department of Geology, Olin Building, Union College, 807 Union Street, Schenectady, New York 12308, USA 3Geotel, URAC 46, Mohammed V University, Scientific Institute, Rabat, Morocco 6 figures; 2 supplemental files CORRESPONDENCE: [email protected] ABSTRACT et al., 2013; Cornée et al., 2014). The combined effects of the MSC make it one of the most important oceanic events in the past 20 m.y. (Krijgsman CITATION: Pratt, J.R., Barbeau, D.L., Jr., Izykowski, The Taza-Guercif Basin is on the southern margin of the former Rifean et al., 1999a). T.M., Garver, J.I., and Emran, A., 2016, Sedimentary provenance of the Taza-Guercif Basin, South Rifean Corridor, one of the major Miocene marine connections between the Atlantic It is widely accepted that the MSC was initiated through the late Miocene Corridor, Morocco: Implications for basin emergence: Ocean and Mediterranean prior to the onset of the Messinian Salinity Crisis. severing of the Betic and Rifean marine corridors (e.g., Krijgsman et al., 1999a; Geosphere, v. 12, no. 1, p. 221–236, doi:10 .1130 As the first basin in the corridor to emerge during corridor closure, the basin Krijgsman and Langereis, 2000; Duggen et al., 2004, 2005; Braga et al., 2006; /GES01192.1. is a key location for understanding this major marine event. To constrain the Jolivet et al., 2006) that connected the Mediterranean Basin with the Atlantic mechanisms for corridor closure, we contribute 499 zircon U-Pb crystalliza- Ocean through Spain and Morocco, respectively. Within the Rifean Corridor, Received 12 April 2015 Revision received 27 October 2015 tion ages and 98 zircon fission-track (ZFT) cooling ages from the stratigraphy the Taza-Guercif Basin of Morocco was one of the first basins to emerge during Accepted 7 December 2015 of the Taza-Guercif Basin. The U-Pb age signature of the Taza-Guercif Basin the progression of corridor closure (Krijgsman et al., 1999b; Garcés et al., 2001; Published online 13 January 2016 is dominated by Pan-African (700–560 Ma) and West African craton (2200– Warny et al., 2003; Sissingh, 2008), although the exact nature of its closure is 1800 Ma) ages, and contains a significant abundance of Mesoproterozoic ages contended. Regional tectonics are considered the primary driver of corridor recently characterized in Mesozoic sediments from the Rif and Middle Atlas closure because changes to glacio-eustatic sea level (Hodell et al., 1989, 1994) mountains. The ZFT ages record a significant Triassic-centered cooling popu- and sedimentation rates (Krijgsman et al., 1999a) are generally considered to lation (275–150 Ma), well-defined Variscan (ca. 330 Ma) and post Pan-African be insufficient to isolate the Mediterranean Sea. Possible tectonic mechanisms (498 Ma) cooling peaks, and a scattering of Precambrian cooling ages. The contributing to corridor closure include craton-ward thrusting in the Rif moun- cooling ages suggest a source in the Middle Atlas; this is consistent with the tains following the cessation of slab rollback in the western Mediterranean U-Pb crystallization ages. Furthermore, there is no discernable change in either (Jolivet et al., 2006), subduction-delamination uplift of the Rif mountains on the U-Pb or ZFT populations during basin emergence. Together, these obser- the African continental margin (Duggen et al., 2003, 2004, 2005), and thermal vations suggest that the Middle Atlas mountains were a consistent source of uplift of the Middle Atlas mountains above thinned lithosphere (Babault et al., sediment to the Taza-Guercif Basin and played a significant role in the closure 2008; Barbero et al., 2011). of the Taza-Guercif Basin and possibly the Rifean Corridor. The Taza-Guercif Basin is between the Rif and Middle Atlas mountains and underwent structural deformation related to both orogens (Bernini et al., 2000). Rif orogenesis was driven by the tectonic collision of the allochthonous INTRODUCTION Alboran domain (Internal Zones; Fig. 1) against the margin of Morocco and deformed through southward-propagating reverse faults (see Chalouan et al., In the late Miocene, the connection between the Mediterranean Sea and 2008). The Atlas Mountains are controlled by inversion of normal faults from Atlantic Ocean was tectonically severed, leading to deep evaporative draw- Triassic– Jurassic extension associated with the opening of the Tethys Ocean down of Mediterranean sea level such that the entire basin approached (see Frizon de Lamotte et al., 2008). The central and eastern Rifean Corridor desiccation in an event known as the Messinian Salinity Crisis (MSC) (Hsü formed above and between Rif and Middle Atlas structures such that short- et al., 1973; Lofi et al., 2011; Roveri et al., 2014). The MSC sequestered 6% of ening and uplift associated with both orogenic belts are possible contributors global ocean salinity into evaporite deposits (Hsü et al., 1977); created a deep, to corridor closure. The Taza-Guercif Basin is just east of the abutment of the dry, and hot basin that altered global atmospheric circulation (Murphy et al., Rifean frontal thrust against the structurally uplifted Tazzeka spur of the Middle 2009); opened passageways for faunal migration between Europe, Africa, and Atlas mountains (Fig. 1). This structural juxtaposition is probably where the For permission to copy, contact Copyright Arabia (Agustí et al., 2006); and ended in the largest flood the Earth has ever marine connection between the Atlantic Ocean and Mediterranean Sea was Permissions, GSA, or [email protected]. experienced (Hsü et al., 1977; Garcia-Castellanos et al., 2009; Pérez-Asensio first severed. © 2016 Geological Society of America GEOSPHERE | Volume 12 | Number 1 Pratt et al. | Sedimentary provenance of the Taza-Guercif Basin Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/1/221/4091825/221.pdf 221 by guest on 02 October 2021 Research Paper 5° W5° E 15° E 25° E 35° E 45° N Alps Halite A Gypsum Apennine Adriatic Sea s Tyrrhenian 40° N Betics Betic Corridor Basin Ionian Basin Rif 35° N Herodotus Rifean Corridor Basin Taza-Guercif basin Middle Atlas 30° N 10° W 6° W 2° W 36° N B 0 200 Alboran Sea Internal kilometers Rif Flysch Nappes External Ri Gharb Tazzeka f Atlantic Ocean Basi TGB n 34° N Saiss B. High ’ Rekkame Plateau ‘Causse Atlas Moroccan Atlas Meseta Missour Folded Middle Basin Eastern Rehamna High Atlas Atlas 32° N High Jebilet GUIR rn Weste Atlas High Ouarzazate B. Anti-Atlas HAMADA ss B. Sou 30° N Cenozoic basins Internal Rif Rifean Flysch Nappes External Rif Approximate extent of the Mesozoic/Cenozoic Major Reverse Atlas system Paleozoic/Precambrian Rifean Corridor Plateaus Faults Figure 1 (on this and following page). (A) Map of the modern Mediterranean displaying the location of major paleogeographic elements related to the Messinian Salinity Crisis. Extent of evaporate deposition modified after Rouchy and Caruso (2006). (B) Geologic map of Morocco modified after Frizon de Lamotte et al. (2008). TGB—Taza-Guercif Basin. GEOSPHERE | Volume 12 | Number 1 Pratt et al. | Sedimentary provenance of the Taza-Guercif Basin Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/1/221/4091825/221.pdf 222 by guest on 02 October 2021 Research Paper 3°57′ W 3°39′ W C Oued Msoun 34°15 ′ TGB1, N TGB2 Taza Bab Stout Brakik Koudiat Plio-Quaternary Zarga Bou Irhardaiene Fm. Kef ed Deba Fm. Melloulou & Ras el Ksar Fms. Draa Sidi Saada Fm. Jurassic substratum Fault Major anticline TGB7 TGB3, TGB4 TGB5, TGB10 TGB12A TGB6 TGB14A Ras el Ksar N BR2 BR3 33°54 ′ N 010 Bou Rached kilometers Figure 1 (continued). (C) Geologic map of the Taza-Guercif Basin modified after Krijgsman et al. (1999a). Locations of samples indicated with red circles. GEOSPHERE | Volume 12 | Number 1 Pratt et al. | Sedimentary provenance of the Taza-Guercif Basin Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/1/221/4091825/221.pdf 223 by guest on 02 October 2021 Research Paper The tectonic interference of the two mountain belts makes determining the is composed of rippled sandstones, biolithites, and alternating siltstones and contribution of uplift from each belt to corridor closure difficult. Our approach mudstones. These strata recorded the assimilation of the Taza-Guercif Basin to solving this problem is to perform a detailed detrital zircon provenance into the Rifean marine corridor. study of the Taza-Guercif Basin stratigraphy as proxy for surface uplift in the Continued subsidence led to the deposition of the open-marine Melloulou Rif and Middle Atlas mountains, the need for which was previously recognized Formation, the base of which consists of thick and uniform marine marls (Gomez et al., 2000). Herein we present the results of the first provenance of its Blue Marl subunit. In the basin depocenter, two turbidite sandstone study of the Taza-Guercif Basin using a combination of detrital-zircon U-Pb systems interfinger with the blue marls: the finer and more thinly bedded crystallization ages and fission-track cooling ages. In Pratt et al. (2015), the El Rhirane turbidites and the coarser, more thickly bedded Tachrift turbidites. detrital zircon signatures of key elements of the Rif and Middle Atlas moun- Current marks suggest a paleoflow from the south, indicating a source in tains were determined using the same methodology, and provide detrital zir- the Middle Atlas (Gelati et al., 2000). The Tortonian-Messinian boundary (ca. con signatures for comparison to the Taza-Guercif sediments.