Sedimentary Provenance of the Taza-Guercif Basin, South Rifean Corridor, Morocco: Implications for Basin Emergence GEOSPHERE; V

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.

5° W5° E 15° E 25° E 35° E

45° N Alps Halite A Gypsum Apennine Adriatic Sea

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.

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.

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. The differences 7.2 Ma) is at or near the top of the Tachrift turbidites (Krijgsman et al., 2000). and similarities between the signal in the Taza-Guercif Basin and those of the The turbidites are overlain by the Gypsiferous Marl subunit, which was de- bounding orogens are used to evaluate the closure of the Rifean Corridor and, posited after rapid shallowing of the basin between 7.2 and 7.1 Ma (Krijgsman by extension, the initiation of the MSC. et al., 1999a). The post-shoaling marl contains abundant gypsum crystals indicating evaporative conditions and is several hundred meters thick (Fig. 2), indicating the continuation of basin subsidence (Krijgsman et al., 1999a; GEOLOGIC BACKGROUND Gelati et al., 2000). Compressional forces became dominant in the Taza-Guercif Basin during The Miocene Taza-Guercif Basin is in the former Rifean Corridor of the early Messinian, caused by the encroachment of the south-vergent Rifean Morocco (Fig. 1). The basin formed in the foreland of the south-vergent Creta- thrust front that inverted preexisting Middle Atlas shear zone structures (Ber- ceous–Holocene Rif mountain fold and thrust belt and is on top of reactivated nini et al., 1999, 2000; Gomez et al., 2000). At the same time, the westward Middle Atlas Triassic–Jurassic rift-related faulting (Bernini et al., 2000). The Rif connection with the Rifean corridor was progressively restricted, leading to mountains are part of the Betic-Rif orocline that rims the Mediterranean Sea lowering sea levels in the basin. The onset of basin emergence is marked by from southern Spain, across the Gibraltar arc, and into Morocco (Fig. 1). This the unconformity overlying the Melloulou Formation and the deposition of the orogenic system formed due to the Cretaceous–Miocene dissection and ac- overlying Kef ed Deba Formation. cretion of a microcontinent, named the Alboran block in the Rif, during slab The Kef ed Deba Formation consists of transitional marine facies that are rollback in the eastern Mediterranean (Chalouan et al., 2008, and references capped by fluvial-deltaic conglomerates and fossiliferous sandstones (Gelati therein). In a different scenario, the Middle Atlas mountains formed from the et al., 2000). These regressive transitional marine facies of the Kef ed Deba Late Cretaceous–Neogene inversion of a failed Triassic–Jurassic rift system Formation are truncated by a stark regional unconformity that marks the final (Frizon de Lamotte et al., 2008). Both orogenic systems accommodated the emergence of the Taza-Guercif Basin between 6.7 and 6.0 Ma (Krijgsman strain in the north African margin due to the convergence with Eurasia, and et al., 1999a, 1999b). Above the unconformity, continental deposition began it is within the context of African-Eurasian convergence that the Taza-Guercif with the lacustrine carbonates and fluvial conglomerates of the Pliocene Bou Basin was formed. Hydrocarbon exploration within the Taza-Guercif Basin has Irhardaiene Formation (Gelati et al., 2000). The postemergence succession provided ample well and seismic data that along with outcrop studies have evolved under the influence of the transpressional Middle Atlas shear zone in constrained the structural and stratigraphic evolution of the Taza-Guercif Basin the absence of further Rifean forcing (Bernini et al., 2000). (e.g., Bernini et al., 2000; Krijgsman et al., 1999a; Gelati et al., 2000; Sani et al., 2000), from which the following summary is simplified. The Neogene evolution of the Taza-Guercif Basin began in the Tortonian METHODS with the formation of a graben system superimposed on the northeastern continuation of the Middle Atlas mountains. The graben-forming extension is Sampling attributed to foreland flexure associated with loading in the external Rif thrust that reactivated Middle Atlas rift structures (Bernini et al., 2000; Sani et al., The analyzed samples obtained from Taza-Guercif Basin stratigraphy 2000) or distal effects of a sinistral shear zone associated with west-southwest– represent all formations with the exception of the monogenetic conglomer- vergent thrusting in the central Rif (Gomez et al., 2000). The onset of extension ates of the Draa Sidi Saada Formation. In all formations, medium to coarse was marked by the deposition of discontinuous continental conglomerates sandstones were targeted for high zircon yields, but often only finer grained and breccias of the Tortonian Draa Sidi Saada Formation. Shallow-marine sed- sandstones were available. In total, nine sandstone samples were selected for imentation followed with the deposition of the Ras el Ksar Formation, which analysis (locations are shown in Figs.1C and 2).

lected from a rust-colored medium-grained sandstone on the uplifted southern

e margin of the basin near the contact with the underlying Jurassic substratum in the vicinity of Bou Rached (TGB14A; 33.9224°, –3.5761°). The sampled bed displays a lenticular base that cuts into a marly bed below. The bed pinches

TGB7 1500 out laterally and where observed is overlain by planar-bedded sandstones. Bou Irhardaien Sample TGB12A was collected from the El Rhirane turbidites between the Melloulou and Zobzit Rivers (TGB12A; 33.9944°; –3.7620°). The El Rhirane tur- TGB10 6.70–6.0 Lacustrine limestone and mudstone bidite sandstones crop out in this area across a low rise, forming small step-like Ke D Fluviatile conglomerate exposures separated by slightly thicker intervals of mudstones. The sample is TGB6 from an ~40-cm-thick tabular bed of rust-colored medium-grained sandstone. TGB5 Transitional deposit Samples TGB3 and TGB4 were collected east of the Zobzit River within a

Marine mudstone with coarsening-upward succession of the Tachrift turbidites that form a ridge over- gypsum crystals looking the village of Timalit (TGB3 and TGB4; 33.9982°, –3.7392°). Each sample

1000 Turbidite sandstone was taken from the uppermost bed of two of different coarsening-upward inter- u vals. Sampled beds are ~1.5 m thick and composed of beige medium-grained Thinly bedded turbidite upward-fining structureless sandstones. Sample TGB3 is the uppermost of the sandstone Melloulo 7.1 2 samples, occurring ~5 m upsection from TGB4. Marine marl Samples TGB5 and TGB6 were acquired from more arenaceous intervals 7.2 Shallow marine within the Gypsiferous Marl subunit exposed east of the Zobzit River on the east- sandstone ern limb of the Safsafat anticline (TGB5 and TGB6; 34.0012°, –3.6593°). Similar TGB3 Main unconformity to the El Rhirane turbidites, the exposures occur on a low rise with sandstones TGB4 interbedded within marl forming discrete step-like ridges. TGB5 was acquired 00 from a dark red to brown ~50-cm-thick fine-grained planar-bedded quartz-rich 7.3 sandstone. TGB6 was sampled ~5–6 m upsection in a 20–30-cm-thick dark red to brown poorly sorted medium- to coarse-grained sandstone. TGB12A Sample TGB10 was collected from the Kef ed Deba Formation within a red 7.5 sandstone interval cropping out on the southern exposure of the eastern limb of the Safsafat anticline (TGB10; 34.0055°, –3.649089°). The sandstone bed is fine grained, ~50-cm-thick, planar bedded, and contains abundant pelecypods. TGB2 TGB7 is the stratigraphically highest sample analyzed in this study and was TGB1 collected from an ~70-cm-thick rippled fine- to medium-grained sandstone TGB14A ReK 8.0 intercalated with the conglomerates of the Bou Irhardaiene Formation ~3 m 0 m5 0600

DS S above a regional unconformity in the Taza-Guercif Basin (TGB7; 34.0070°, Bathymetry Stratigraphic –3.6492°). The surrounding pebble-cobble conglomerates are matrix poor and (meters) Age (Ma) observed clasts consist almost entirely of carbonate. Figure 2. Stratigraphic column of Taza-Guercif Basin (TGB) sediments with paleobathymetry modified after Krijgsman et al. (1999a). DSS—Draa Sidi Saada Formation; Rek—Ras el Ksar For- mation; KeD—Kef ed Deba Formation. Detrital Zircon U-Pb Geochronology

Seven samples (TGB1, TGB4, TGB5, TGB7, TGB10, TGB12A, TGB14A) were Three samples were collected from the Ras el Ksar Fm. TGB1 (sample prefix analyzed using laser ablation–single-collector–inductively coupled plasma– TGB—Taza-Guercif Basin) was sampled in the Bab Stout region in the north of mass spectrometry (LA-SC-ICP-MS) at the University of South Carolina’s Cen- the basin ~10 m upsection of the contact with the underlying Draa Sidi Saada ter for Elemental Mass Spectrometry. Our procedure was detailed in Pratt et al. Formation (34.2402°, –3.8564°). The outcrop consists of a 1–2 m pitted and bio- (2015) and is only briefly summarized here. Following standard rock disaggre- turbated beige fine- to medium-grained sandstone that is tabular and laterally gation and zircon separation techniques, samples were ablated with a Photon- continuous. Sample TGB2 was collected ~5 m upsection from TGB1, separated Machines 193 nm ArF excimer laser and the ablated material was plumbed to by fine-grained slope-forming rock, and similarly is a 1–2-m-thick beige fine- to and analyzed in a Thermo Scientific Element2 high-resolution SC-ICP-MS. Our medium-grained pitted and bioturbated sandstone. Sample TGB14A was col- analysis measured the signal intensities of 202Hg, 204(Pb + Hg), 206Pb, 207Pb, 208Pb,

232Th, and 238U. Each sample analysis targeted ~100 unknown zircons and incor- grains and caution should be applied when comparing directly to results from porated an analysis of the natural zircon standard SL2 (563.2 ± 4.8 Ma; Gehrels conventional optical fission-track analysis. et al., 2008) after every fifth unknown, and R33 (419.3 ± 0.4 Ma; Black et al., Zircons were extracted from the same separates produced for the U-Pb 2004) after every twentieth unknown. Each individual grain analysis included analysis to produce grain mounts for four samples (TGB3, TGB6, TGB12A, a 10 s blank integration followed by 28 s of analysis during 10 Hz ablation by and TGB14A) in addition to three mounts of natural standards for zeta calibra- a 25 mm circular spot, followed by 15 s for post-ablation chamber wash-out. tion: the Buluk Tuff (16.4 ± 0.2 Ma fission-track age), Fish Canyon Tuff (27.9 ± Data reduction was performed in the Iolite software add-on (Paton et al., 0.5 Ma), and Peach Springs Tuff (18.5 ± 0.1 Ma). Etching proceeded for 5–7 h 2011) for WaveMetric’s IgorPro software utilizing the U-Pb Geochronology3 in a KOH:NaOH eutectic at 228 °C. The mounts were then flattened, cooled, Data Reduction Scheme. Data were corrected for background signals, down- and cleaned prior to affixation with an ~0.2 mm mica flake. The mounts and hole fractionation, and instrument drift to produce the final isotopic ratios and 3 glass dosimeters with a 238U content of 12.3 ppm were irradiated in Oregon ages (Supplemental Table 11). Final analyses with 2s error >20% in either the State University’s TRIGA Mark II Reactor. Following irradiation, the mica de- 238U/206Pb or 207U/206Pb ages were disregarded. Resulting analyses with 238U/206Pb tectors were etched in 48% HF for ~18 min. The mounts and corresponding ages older than 500 Ma were subjected to a concordance filter whereby any mica detectors were mounted as mirror images on petrographic slides with an grains with >30% normal discordance or >5% reverse discordance were sim- ~8–10-nm-thick carbon coating and imaged at ~3000–10,000× using the sec- ilarly disregarded. Grains with 238U/206Pb ages younger than 500 Ma were ondary electron detector of a Zeiss EVO50 tungsten-filament SEM. retained regardless of discordance. Herein we use 238U/206Pb ages for grains Natural and induced fission-track densities were determined using spatial with ages younger than 1.3 Ga, and 207Pb/206Pb ages for grains with 238U/206Pb analysis of the secondary electron images in the ImageJ software package ages older than 1.3 Ga. This age division was chosen to reduce individual age (http://imagej .nih .gov /ij/). The number of spontaneous fission tracks preserved uncertainty and to avoid skewing a population that extends across the more in the zircon, induced fission tracks in the mica, and image area were entered conventional 1.0 Ga age-method division. into ZetaAge (Brandon, 1996) and DensityPlotter (Vermeesch, 2009, 2012) to determine grain ages, kernel density estimates (KDE), and mixture model Detrital Zircon Fission-Track Geochronology peaks. The mixture model attempts to fit a discrete number of cooling events to the fission-track ages where peaks are located at the age of the event and Supplemental Table 1. Detrital zircon U-Pb data

Ras el Ksar Fm (Bab Stout) Zircon fission-track (ZFT) thermochronology provides ages at which zir- distribution of ages about the peaks is due to partial resetting (Brandon, 1996). TGB1 Ratios Ages 207 235 206 238 d 207 206 206 238 207 235 207 206 #U [ppm]Th/U Pb/ U 2 σ Pb/ U 2 σ rho Pb/ Pb 2 σ Pb/ U 2 σ Pb/ U 2 σ Pb/ Pb 2 σ %Conc TGB1_2 1660.019 0.797 0.043 0.095 0.0030.263 0.062 0.003 583 18 592 25 633 96 92.1 TGB1_5 54 0.426 0.930 0.120 0.097 0.0030.380 0.071 0.009 597 16 652 56 810 22073.7 cons cool below the closure temperature, which is typically ~250 °C for aver- To create a mixture model DensityPlotter chooses the number of age com- TGB1_15 1760.256 2.05 0.053 0.190 0.0040.384 0.080 0.002 1121 23 1129 18 1196 52 93.7 TGB1_16 6210.037 0.7 0.026 0.092 0.0030.705 0.060 0.002 568 18 56 15 596 60 95.3 TGB1_19 6600.072 0.761 0.035 0.089 0.0050.820 0.065 0.002 551 29 577 19 768 64 71.7 TGB1_21 1530.577 13.650 0.380 0.508 0.0140.821 0.19 0.003 267 62 2723 26 2771 26 95.5 age zircons (Fleischer et al., 1975; Tagami and O’Sullivan, 2005). These ages ponents by minimizing the Bayes Information Criterion and determines their TGB1_30 77 0.124 6.530 0.200 0.371 0.0090.586 0.127 0.003 2031 42 207 27 2051 43 99.0 TGB1_31 3480.208 0.832 0.029 0.096 0.0030.580 0.062 0.002 589 15 61 16 66 58 88.7 TGB1_34 62 0.208 3.990 0.480 0.283 0.0210.407 0.102 0.012 1600 110 1689 88 1790 12089.4 are determined using the density of fission-induced damage trails, or fission value using a hybrid deterministic and Markov chain Monte Carlo method (Ver- TGB1_36 89 0.275 1.669 0.069 0.165 0.0040.492 0.073 0.003 982 24 99 26 1019 78 96.4 TGB1_37 2060.371 0.737 0.038 0.08 0.0020.378 0.06 0.003 520 14 559 22 710 11073.2 TGB1_38 35.1 0.150 6.560 0.240 0.356 0.0110.619 0.130 0.004 1968 50 209 33 2090 52 94.2 238 TGB1_43 1350.156 0.913 0.043 0.107 0.0030.559 0.062 0.003 653 19 656 23 651 96 100.3 tracks, in the crystal lattice of the zircons and the rate at which U under- meesch, 2009, 2012). The KDE creates a curve of the relative probability that TGB1_45 2010.339 0.829 0.037 0.092 0.0020.211 0.06 0.003 570 13 611 20 728 81 78.3 TGB1_46 5530.191 0.751 0.024 0.091 0.0020.579 0.060 0.001 560 13 570 13 608 52 92.1 TGB1_47 1251 0.054 0.352 0.015 0.06 0.0020.651 0.05 0.002 292 11 306 11 37 75 84.1 goes spontaneous fission. Above the closure temperature, fission tracks are a randomly selected grain from an infinite population would occur at a given TGB1_50 1780.604 0.75 0.039 0.090 0.0020.181 0.059 0.003 552 13 563 23 577 99 95.7 TGB1_51 2750.442 1.31 0.082 0.139 0.0080.821 0.069 0.002 83 45 858 36 893 65 94.4 TGB1_55 1870.375 0.78 0.030 0.09 0.0030.544 0.060 0.002 581 16 589 17 588 71 98.8 TGB1_56 2820.061 0.751 0.033 0.090 0.0030.548 0.060 0.003 556 17 567 19 569 95 97.7 repaired and below the closure temperature, fission tracks are retained. Thus age based on the density distribution of sampled ages (Vermeesch, 2012). TGB1_57 5610.313 5.310 0.150 0.315 0.0080.898 0.122 0.002 1766 40 1873 22 1987 23 88.9 TGB1_59 1860.122 1.130 0.073 0.123 0.0070.817 0.067 0.002 76 42 768 36 867 73 86.0 TGB1_60 3100.153 0.803 0.026 0.097 0.0030.580 0.060 0.002 59 14 597 14 603 61 98.5 TGB1_61 1860.432 0.905 0.036 0.099 0.0030.495 0.066 0.002 610 17 656 19 828 75 73.7 reheating above the closure temperature resets the fission-track age (Naeser, TGB1_62 5500.102 0.801 0.024 0.095 0.0020.726 0.061 0.001 583 14 597 13 619 50 94.2 TGB1_69 227.40.231 1.61 0.060 0.163 0.0040.726 0.073 0.002 975 24 987 23 1009 42 96.6 TGB1_71 1720.056 .610 0.740 0.262 0.0400.965 0.125 0.007 170 210 1690 160 2000 11073.5 1979; Bernet and Garver, 2005). The distribution of fission-track ages from de- TGB1_72 94.8 0.394 11.380 0.320 0.21 0.0110.820 0.19 0.003 227 51 2566 25 2776 28 81.9 TGB1_74 4860.168 0.828 0.028 0.098 0.0020.664 0.060 0.001 601 13 612 16 612 52 98.2 TGB1_75 92.9 0.366 0.721 0.035 0.089 0.0020.312 0.060 0.003 57 12 553 21 597 99 91.6 TGB1_76 145.80.168 1.26 0.046 0.1 0.0050.405 0.070 0.002 868 26 902 18 95 72 91.0 trital zircons in a sedimentary sample can provide a unique signature separate RESULTS TGB1_81 3860.084 0.751 0.066 0.088 0.0070.830 0.061 0.003 51 41 569 41 590 12091.7 TGB1_82 90.4 0.185 0.660 0.049 0.079 0.0030.618 0.060 0.004 90 15 510 30 560 14087.5 TGB1_83 3330.326 5.370 0.140 0.326 0.0090.832 0.116 0.002 1818 44 1878 22 1899 26 95.7 from the U-Pb crystallization ages. The combination of the two signatures bet- TGB1_85 1430.445 1.397 0.068 0.137 0.0040.605 0.072 0.003 829 23 889 28 980 73 84.6 TGB1_89 59 0.247 0.565 0.050 0.070 0.0020.381 0.058 0.005 3 12 50 33 90 18088.6 TGB1_91 5570.159 .810 0.380 0.277 0.0220.973 0.12 0.002 1570 110 176 70 2016 30 77.9 TGB1_92 3950.236 0.757 0.032 0.089 0.0030.732 0.061 0.002 58 18 571 19 65 64 85.0 ter discriminates between potential source rocks and is particularly valuable in Zircon U-Pb Results TGB1_93 3620.175 8.790 0.410 0.369 0.0160.909 0.170 0.003 2023 74 2308 43 2558 29 79.1 TGB1_94 2400.138 6.050 0.180 0.32 0.0090.792 0.128 0.002 1896 45 198 25 2067 29 91.7 TGB1_95 1430.431 17.30 0.570 0.96 0.0150.903 0.256 0.004 2591 66 2960 33 3217 23 80.5 TGB1_96 2220.228 5.590 0.440 0.298 0.0210.976 0.137 0.002 1700 100 1925 66 2185 31 77.8 in areas, such as Morocco, where crystallization ages are likely to be uniform TGB1_98 1910.131 3.680 0.140 0.259 0.0080.620 0.103 0.003 18 41 1563 30 1678 42 88.4 TGB1_99 200.30.191 0.675 0.029 0.085 0.0020.327 0.058 0.003 527 14 522 18 517 94 101.9 TGB1_101 5090.341 0.757 0.021 0.090 0.0020.727 0.061 0.001 557 12 571 12 625 38 89.1 but have a more heterogeneous low-temperature thermal history. We analyzed 638 zircons in the course of this study. After error and concor- TGB1_102 6050.063 0.805 0.033 0.093 0.0040.857 0.06 0.002 575 26 598 18 726 73 79.2 TGB1_103 4340.311 0.767 0.030 0.096 0.0020.646 0.060 0.002 589 14 585 16 586 55 100.5 TGB1_105 2690.003 0.85 0.043 0.098 0.0030.698 0.063 0.002 600 19 623 24 700 80 85.7 TGB1_107 4240.706 0.787 0.040 0.092 0.0030.031 0.062 0.002 567 16 587 22 60 86 88.6 The ZFT analysis of our samples was performed using the scanning elec- dance filtering, analysis yielded 500 individual zircon U-Pb ages from 7 sam- TGB1_108 111.90.568 0.580 0.035 0.073 0.0030.453 0.059 0.004 55 19 66 22 550 12082.7 TGB1_112 80.6 0.298 0.395 0.039 0.05 0.0020.174 0.055 0.005 30 11 3 28 380 18089.5 TGB1_113 168.10.315 5.170 0.120 0.301 0.0070.795 0.126 0.002 1697 36 1850 21 2035 32 83.4 tron microscope high-density fission-track (SEM-HDFT) technique (e.g., Mon- ples, TGB14A, TGB1, TGB12A, TGB4, TGB5, TGB10 and TGB7 (see Supplemen- TGB1_115 246.40.241 0.729 0.032 0.088 0.0020.314 0.060 0.002 5 13 55 19 620 64 87.7 TGB1_116 4200.292 5.320 0.200 0.316 0.0140.875 0.123 0.003 1765 68 1867 32 2005 40 88.0 TGB1_117 243 0.309 0.79 0.039 0.09 0.0020.536 0.062 0.003 579 13 591 22 680 82 85.1 TGB1_118 117.30.427 0.593 0.047 0.070 0.0020.189 0.061 0.005 38. 9.4 68 30 570 16076.9 tario and Garver, 2009). This technique utilizes higher magnifications and tal Table 1). Age spectra for individual samples as well as the composite of the TGB1_119 2880.201 2.592 0.086 0.217 0.0060.437 0.087 0.002 1266 30 1296 24 136 43 92.8 TGB1_120 2200.538 1.100 0.046 0.119 0.0030.607 0.067 0.002 726 16 751 22 831 66 87.4 TGB1_14 48 0.011 0.692 0.029 0.075 0.0040.914 0.068 0.001 65 21 532 17 880 37 52.8 TGB1_29 0.53 0.036 3.800 0.510 0.075 0.0070.153 0.395 0.059 63 40 1670 120 3980 23011.6 gentler etching techniques to allow the counting of zircon fission tracks at Taza-Guercif Basin are shown in Figure 3. TGB1_33 1.20.015 0.820 0.300 0.076 0.0120.540 0.13 0.049 70 71 723 87 1890 53024.9 TGB1_44 32 0.012 0.860 0.220 0.081 0.0160.779 0.070 0.006 98 90 581 93 910 13054.7 8 2 TGB1_63 35 0.013 0.609 0.084 0.057 0.0060.177 0.069 0.010 355 36 68 60 80 37042.3 high densities (3 × 10 tracks/cm ), thereby unlocking cooling ages in highly The composite of Taza-Guercif Basin samples contains ages ranging from TGB1_84 0.0086 0.131 2.090 0.270 0.01 0.0020.584 1.100 0.150 88 14 1155 92 5620 3501.6 TGB1_87 7.40.030 3.260 0.140 0.080 0.0040.433 0.292 0.013 99 21 173 32 337 74 14.5 TGB1_104 0.59 0.010 0.82 0.040 0.065 0.0020.302 0.05 0.004 08 12 396 28 370 170 110.3 TGB1_110 6.20.011 0.653 0.045 0.07 0.0030.402 0.063 0.004 61 16 512 29 690 15066.8 radiation damaged grains, as are common to old and/or high [U] crystals. 3570 to 68 Ma and contains 2 dominant populations. The largest population The closure temperature for radiation-damaged grains is between ~150 and contains 228 ages between 693 and 518 Ma, representing 45.6% of all analyzed 1 Supplemental Table 1. Detrital zircon U-Pb data. 195 °C. Details of the technique can be found in Montario and Garver (2009); grains. The second-largest population with 78 grains consists of ages that are Please visit http://dx.doi.org/10 .1130/GES01192.S1 or the full-text article on www.gsapubs.org to view our procedure was presented in detail in Pratt et al. (2015), and is only briefly between 2185 and 1790 Ma, and represents 15.6% of the total population; <9% Supplemental Table 1. summarized here. This method preferentially targets nearly metamict zircon of all grains are younger than the 518 Ma lower limit of the primary age peak,

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 226 by guest on 02 October 2021 on 02 October 2021 by guest Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/1/221/4091825/221.pdf Research Paper generated in DensityPlotter (Vermeesch, 2009). Left panel displays ages from 0 to 1100 Ma. Right panel displays full age spectra from 0 to Ma. 3500 Figure 3. U-Pb zircon age kernel density estimates (KDE) and pie charts for individual samples and the Taza-Guercif Basin (TGB) composite. KDEs were # of Grains # of Grains # of Grains # of Grains # of Grains # of Grains # of Grains # of Grains 10 40 20 2 6 0 2 4 6 8 0 2 4 0 0 4 8 0 2 4 6 0 2 4 6 0 2 4 6 0 2 4 6 0 0 0 0 0 0 All TGB 0 0 (Bou Rached) Ras el Ksar (Bab Stout) Ras el Ksar El Rhirane turbidites Gypsiferous Mar l Kef ed Deba Bou Irhardaiene Tachrift turbidites TGB4 (n=47) TGB5 (n=47) TGB10 (n=41) TGB12A (n=37) TGB7 (n=48) AllTGB (n=331) TGB1 (n=49) TGB14A (n=62) 100 100 100 100 100 100 100 100 200 200 200 200 200 200 200 200 300 300 300 300 300 300 300 300 400 400 400 400 400 400 400 400 463 489 Age (Ma) 500 500 500 500 500 500 500 500 550 554 534 571 541 534 600 600 600 600 600 600 600 600 583 579 600 598 597 585 622 619 619 637 637 633 700 700 700 700 700 700 700 700 692 683 800 800 800 800 800 800 800 800 844 888 900 900 900 900 900 900 900 900 926 888 955 1000 1000 1000 1000 1000 1000 1000 1000 1003 1023 993

1100

1100 1100 1100 1100 1100 1100 1100

Probability Probability y robabilit yP Probabilit Probability Probability Probability y Probabilit 3% 10 % 10 % 12 % 11 12 % 15 % 11 19 % 15 % 26 % 18 % 18 % 20 % 21 % 0.64-1.0 Ga 0.54-0.64 Ga <0.54 Ga 23 % 15 % 19 % % % 17 % 8% 16 % 7% 4% 15 % 15 % 8% 6% 5% 3% 16 % 36 % 12 % 13 % 23 % 15 % 10% 18% 3% 7% 25% 30% 39% 40% 41% 35% 32% 23% >2.5 Ga 1.6-2.5 Ga 1.0-1.6 Ga

# of Grains # of Grains # of Grains # of Grains # of Grains # of Grains # of Grains # of Grains 12 30 60 90 12 16 12 12 12 10 0 4 8 0 0 4 8 0 2 4 6 0 4 8 0 4 8 8 0 3 6 9 0 2 4 6 0 0 0 0 0 0 0 0 463 400 400 400 400 400 400 541 549 400 400 580 585 619 575 800 800 800 609 599 800 596 800 800 800 841 800 870 983 943 1003 909 1019 120 0 120 0 120 0 1200 120 0 120 0 120 0 120 0 1 1 1232 172 1217 172 160 0 160 0 160 0 Age (Ma) 160 0 160 0 160 0 1558 160 0 160 0 200 0 1963 2045 200 0 200 0 200 0 200 0 200 0 200 0 200 0 2013 2071 2066 2016 2019 2126 2400 240 0 240 0 240 0 240 0 240 0 240 0 240 0 280 0 280 0 280 0 TGB14A (n=93 ) TGB12A (n=62 ) AllTGB (n=499) 280 0 280 0 280 0 280 0 280 0 TGB10 (n=58) TGB5 (n=74) TGB7 (n=74) TGB4 (n=71) TGB1 (n=67) 3200

320 0 320 0 320 0 320 0 320 0

3200 320 0

y robabilit y Probabilit yP Probabilit Probability Probability Probability Probability Probability

GEOSPHERE | Volume 12 | Number 1 Pratt et al. | Sedimentary provenance of the Taza-Guercif Basin 227 Research Paper

and only 7% are older than 2185 Ma. Individual samples are all generally very DISCUSSION similar to the composite spectrum (Fig. 3). For brevity, the populations in each individual sample are reported Figure 3, and the differences between individ- Basin-Scale Provenance ual samples are discussed later in the text. Examining the detrital zircon U-Pb crystallization age data from the Taza-Guercif Basin as a whole reveals a dominant Pan-African signal as ZFT Results demonstrated by the robust ca. 700–520 Ma population (Fig. 3). These Pan-African ages represent a period of orogenesis and magmatism that oc- SEM high-definition fission-track (SEM-HD-FT) analysis yielded results curred during the coalescence of Gondwana in the latest Proterozoic and from 99 zircon grains from 4 samples from the Taza-Guercif Basin (TGB14A, earliest Paleozoic (Stern, 1994, 2002). This population combined with the ca. TGB12A, TGB3, and TGB6) (see Supplemental Table 22). Greater grain counts 2.2–1.8 Ga Paleoproterozoic U-Pb crystallization ages composes a signature were obtained for TGB12A and TGB3, which contain 35 and 40 grains, respec- typical of sediment derived from the West African craton and its Pan-African tively, whereas the remaining 2 samples measured 11 and 13 grains. Analysis margin (Fig. 5; Nance and Murphy, 1994; Abati et al., 2010; Avigad et al., of a fifth sample, TGB7, was attempted, but yielded too few appropriate zircons 2012). The smaller population at ~950 Ma crystallization age is not typical after those for U-Pb analysis were separated. The 95% confidence interval for of the West African craton crystalline basement, but has been identified in individual ages is regularly in excess of 100 m.y. above and below the calcu- Ediacaran–Cambrian exposures in the Anti-Atlas mountains (Avigad et al., lated age. KDEs and mixture model peaks were generated for each sample and 2012), in the Internal Zones of the Betic-Rif arc in Spain (Fig. 1; Platt and are shown in Figure 4. The mixture model attempts to fit a discrete number of Whitehouse, 1999; Zeck and Whitehouse, 1999, 2002; Zeck and Williams, cooling events to the fission-track ages where peaks are located at the age of 2001), as well as in Mesozoic exposures in the Middle Atlas and Rif moun- the event and deviation about the peaks is due to partial resetting. The KDE tains (Fig. 5; Pratt et al., 2015). uses the density of sampled ages to compute a curve of the probability that a While it is unsurprising that these northwest African samples show a dom- randomly chosen grain would fall at a given age if the population were sam- inant signal from the West African craton, the presence of Mesoproterozoic ples infinitely. ages as represented by a small population peak ca. 1190 Ma is significant. To Ras el Ksar sample TGB14A (n = 13) produced KDE peaks at 198, 259, and date, Mesoproterozoic zircons have only been identified in Morocco within the 506 Ma with mixture model peaks occurring at 228 ± 21 Ma, 510 ± 55 Ma, and Mesozoic samples mentioned above. In general, Mesoproterozoic zircon crys- 1037 ± 343 Ma (Fig. 4). The mixture model is in good agreement with the KDE tallization ages are rare in the region, occurring only in small abundances in peaks with the exception that the mixture model lumped the two youngest other exposures across North Africa and not coevally with the ca. 1190 peak Supplemental Table 2. Detrital zircon fission-track data

TGB3 Tachrift Turbidites peaks defined by the KDE. Statistically, the 2 KDE peaks are inseparable based observed here (Thomas et al., 2010; Linnemann et al., 2011). RhoD % errorU(ppm)Zeta1 Area 3.307E+051.5212.30 321.910.61.000E-08 on the 95% confidence interval of individual ages. In the thermochronologic data, all of the studied Taza-Guercif Basin strata Grain S Ns I NI SquaresU 2 Age95% CI 15.52E+07 107 2.21E+07 45 204820 245 125.1 87.8 181.2 29.91E+07 336 5.31E+06 18 339197 92 916.6 590.41507.7 El Rhirane turbidite sample TGB12A (n = 35) displays KDE peaks at 237, contain a ZFT cooling age population centered on the Triassic (Fig. 4), span- 35.96E+07 202 1.21E+07 41 339450 140 256.2 183.8366.3 44.66E+07 158 4.42E+06 15 339165 84 532.5 321.3952.4 57.43E+07 252 3.54E+06 12 339132 75 1018.5 599.31888.2 323, and 489 Ma, and mixture model peaks occur at 203 ± 36, 323 ± 27, and ning from the Permian to the Late Jurassic (ca. 285–160 Ma). The age range of 67.17E+07 243 7.08E+06 24 339263 107 514.5 343.9805.9 75.28E+07 179 9.14E+06 31 339340 122 298.9 205.4450.2 85.22E+07 177 5.60E+06 19 339208 95 474.1 300.8793.1 606 ± 78 Ma (Fig. 4). The KDE and mixture model peaks occur at similar ages this cooling population coincides with late Variscan magmatism that affected 98.24E+07 168 4.41E+06 9 204164 107 909.4 491.41901.7 10 4.40E+07 149 5.90E+06 20 339219 97 382.2 242.8636.1 11 8.61E+07 292 5.31E+06 18 339197 92 803.3 515.01331.4 for the youngest two peaks. A mismatch occurs with the third peak where the the Moroccan Meseta (Michard et al., 2008, and references therein), the Trias- 12 6.08E+07 206 7.08E+06 24 339263 107 438.8 291.5691.7 13 3.69E+07 125 1.09E+07 37 339406 133 176.8 122.4262.0 14 5.37E+07 182 8.26E+06 28 339307 115 335.4 227.2514.7 mixture model combines the grains represented by the 489 Ma KDE peak with sic rifting of the Atlas basins and the Central Atlantic Magmatic Province lava 15 8.04E+07 193 7.92E+06 19 240294 134 515.3 328.1858.7 16 4.69E+07 159 6.49E+06 22 339241 102 371.3 240.6602.8 17 4.25E+07 144 3.54E+06 12 339132 75 601.8 344.81155.8 all older ages. flows in Morocco (Knight et al., 2004; Verati et al., 2007; Frizon de Lamotte 18 4.72E+07 160 7.37E+06 25 339274 109 330.2 218.5521.1 19 5.49E+07 186 8.85E+06 30 339329 120 320.4 219.5484.8 20 4.69E+07 159 8.26E+06 28 339307 115 294.0 198.0453.5 The spectra for the Tachrift turbidite sample TGB3 (n = 40) yielded 3 strong et al., 2008), and Early Jurassic magmatism that occurred in the High Atlas 21 4.93E+07 167 9.73E+06 33 339362 126 262.8 181.7392.4 22 6.05E+07 205 2.95E+06 10 339110 68 993.7 556.11975.1 23 3.24E+07 110 9.73E+06 33 339362 126 174.4 118.0265.1 KDE peaks at 181, 323, and 489 Ma. Mixture model peaks for TGB3 were cal- (Frizon de Lamotte et al., 2008, and references therein) with coeval hydro- 24 7.63E+07 183 8.33E+06 20 240310 137 466.2 298.9769.1 25 5.69E+07 78 8.76E+06 12 137326 185 333.2 184.4633.3 culated as 172 ± 19 Ma, 323 ± 37 Ma, and 592 ± 50 Ma (Fig. 4). The mixture thermal events in the Middle Atlas (Hamidi et al., 1997; Auajjar and Boulègue, 26 6.79E+07 93 6.57E+06 9 137244 159 519.6 271.51135.1 27 4.37E+07 148 3.54E+06 12 339132 75 617.7 354.41184.5 28 6.64E+07 225 6.78E+06 23 339252 104 497.6 329.4788.9 model and KDE peaks produce similar young peaks, while the oldest peaks in 2002; Dekayir et al., 2005). 29 3.81E+07 129 5.01E+06 17 339187 89 388.6 238.0678.3 30 5.55E+07 188 7.37E+06 25 339274 109 386.2 257.4605.6 31 3.54E+07 120 3.54E+06 12 339132 75 505.4 286.9981.1 each model deviate significantly. The issue is the same as TGB12A, where the All samples except for TGB14A also contain a population of grains with 32 8.47E+07 287 7.96E+06 27 339296 113 539.4 369.5820.1 33 6.84E+07 232 7.08E+06 24 339263 107 492.1 328.4772.1 34 4.25E+07 144 1.06E+07 36 339395 131 208.8 145.0308.8 mixture model lumps the oldest half (52% ± 13%) together to define one peak. ZFT ages ca. 330 Ma, coeval with the early period of Variscan tectonics and 35 5.34E+07 181 5.01E+06 17 339187 89 538.6 335.0925.4 36 4.72E+07 160 8.55E+06 29 339318 118 285.9 193.6437.9 37 3.81E+07 129 4.13E+06 14 339154 81 467.9 275.7862.6 Sample TGB6 from the Gypsiferous Marl (n = 11) displays three dominant magmatism that affected the Moroccan Meseta and the Anti-Atlas mountains 38 7.02E+07 238 5.31E+06 18 339197 92 662.6 421.21108.2 39 2.63E+07 89 6.49E+06 22 339241 102 210.6 132.3351.3 40 3.27E+07 111 1.00E+07 34 339373 128 170.9 116.2258.3 KDE peaks at 223, 335, and 957 Ma. Mixture model peaks are calculated as (Michard et al., 2008). In the Taza-Guercif Basin composite ZFT spectrum, this 171 ± 26, 336 ± 29, and 959 ± 300 Ma (Fig. 4). The two models are in near per- peak is the best defined and of greatest amplitude (Fig. 6). This suggests that 2 Supplemental Table 2. Detrital zircon fission-track fect agreement, with the only difference occurring in the age of the youngest the zircons of this population were not affected by subsequent annealing data. Please visit http://dx .doi .org /10 .1130/GES01192 .S2 or the full-text article on www.gsapubs.org to peak. However, the difference in these ages is within the 95% confidence inter- during the latter phases of the Variscan orogeny or during the Mesozoic ex- view Supplemental Table 2. val for individual grain ages. tension that followed.

3 171± 336± 959± (23± (68± (9± 203± 312± 606± (12± (64± (23± 22%) 15%) 16%) 26 29 300 12% ) 13% ) 18% )

Gypsiferous Marl 36 27 78 El Rhirane turbidites TGB6 (n=11) TGB12A (n=35) 7 2

335 Probability 6 323

5 Probability 4 # of Grains 1 3 223 237 # of Grains 2 489 957 1

0 0

0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Age (Ma) Age (Ma) 228± 510± 1037± (46± (46± (8± 21% ) 14% ) 15% ) 172± 323± 592± 21 55 (13.3± (35± (52± 343 Ras el Ksar 11%) 13%) 6.1%) 19 37 50 Tachrift turbidites 2 TGB14A (n=13) TGB3 (n=40) Probability Probability 259 506 4 518 198 3 1 323 2 # of Grains # of Grains 181 1

0 0

0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Age (Ma) Age (Ma)

Figure 4. Zircon fission-track age kernel density estimates (KDE). Mixture model peaks are shown with dashed lines. KDE and mixture models were generated in DensityPlotter (Vermeesch, 2009). TGB—Taza-Guercif Basin.

Samples TGB14A and TGB3 contain a significant KDE cooling age peak in Evaluation of the Middle Atlas and Rif Mountains as Zircon Sources the Cambrian, whereas sample TGB12A displays a minor peak during this time (Fig. 4). The absence of this population in the remaining sample, TGB6, may In the late Miocene both the Rif and Middle Atlas mountains were de- simply result from its comparatively small grain count, as it otherwise closely forming adjacent to the Taza-Guercif Basin. The Middle Atlas mountains were resembles TGB12A. These Proterozoic cooling ages may reflect distinct cool- undergoing broad thermal uplift (e.g., Teixell et al., 2005; Barbero et al., 2007; ing events, but were likely subject to various degrees of reheating and partial Babault et al., 2008) while the encroachment of the Rif thrust front reactivated resetting and as such are not diagnostic. Middle Atlas structures and caused shortening in the Rif domain (Bernini

660 60 597 Rif Mountains composite (n=141) Anti-Atlas (n=220) 24 (Pratt et al., 2015) 40 Probabilit y

middle Cambrian Probabilit y (Avigad et al., 2012)

12 2017 # of Grains 20 950 2093 # of Grains 9741175

0 0

0 400 800 1200 1600 2000 2400 2800 3200 0 400 800 1200 1600 2000 2400 2800 3200

590 Taza-Guercif Basin composite (n=499) Alboran domain (n=81) 90 (this study) 301590 (Platt & Whitehouse, 1999; Probability 8 Zeck & Whitehouse, 1999, 2002; Probabilit y 60 959 Zeck & Williams, 2001)

4 30 2023 # of Grains # of Grains 939 1185

0 0

0 400 800 1200 1600 2000 2400 2800 3200 0 400 800 1200 1600 2000 2400 2800 3200 Age (Ma)

638 Bou Rached Sandstones (n=118) 12 (Pratt et al., 2015)

437 Probabilit y 8 2082 Figure 5. Comparison of U-Pb spectra from relevant terranes. 4 2522 # of Grains 0

0 400 800 1200 1600 2000 2400 2800 3200 Age (Ma)

et al., 1999, 2000; Gomez et al., 2000). Due to their immediate proximity to Sidi Saada and Ras el Ksar Formations and compose part of the Jurassic sub- the Taza-Guercif Basin and their elevation, these two mountain ranges are the stratum, as confirmed by borehole and seismic data (Sani et al., 2000). In some most likely sources of sediment to the basin. The currently available data and portions of the basin, the sandstones are capped by upper Jurassic limestones geologic histories of these potential source areas are compared and evaluated and in other parts, particularly the margins of the basin, they immediately in relation to the both the detrital zircon U-Pb crystallization ages and the ZFT underlie the Miocene basin fill beneath a dramatic angular unconformity. cooling ages obtained from the sediments of the Taza-Guercif Basin. Despite this relationship, the composite U-Pb crystallization age spectrum of the Taza-Guercif Basin does not match that of the Middle Atlas Bou Rached Jurassic sandstones (Fig. 5), although the latter may be a minor contributor to Middle Atlas the former. Detrital zircon U-Pb age spectra from the Bou Rached sandstones contain a 500–400 Ma population that accounts for <0.5% of grains in the Taza- In the Middle Atlas, the only available U-Pb or ZFT data come from the Guercif composite age-distribution curve while composing >10% of the grains Jurassic (Bathonian–Callovian) Bou Rached sandstones sampled in the north- in the Bou Rached sandstones. The Bou Rached sandstones display a character- ern Middle Atlas near the contact with Miocene sediments of the Taza-Guercif istic gap in U-Pb ages between 560 and 500 Ma not present in the Taza-Guercif Basin (Fig. 1C; Pratt et al., 2015). These sandstones extend beneath the Draa Basin samples and contain a larger proportion of Archean ages (Fig. 5).

316 Tisiren and Ketama units Taza-Guercif Basin, although the possibility of a contribution from interbedded 3 434 Rif

Probability quartzose lithologies cannot be excluded. 115 583 (n=33) 2 Farther south in the Middle Atlas, the Jurassic carbonates are overlain by

1 lower Cretaceous continental red beds that were subsequently covered in

# of Grains the Late Cretaceous by sediments deposited during a regional transgression 0 (Faure-Muret and Choubert, 1971; Frizon de Lamotte et al., 2008). The Creta- 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 ceous continental and marine successions are preserved in the southern half Age (Ma) 5 of the Middle Atlas and are mostly absent to the north. This missing cover may represent a viable distal source from the Middle Atlas to the Miocene

4 Bou Rached Sandstones Taza-Guercif Basin.

Middle Atlas Probability 3 336 428 (n=26) 141 Rif 2 # of Grains

1 Limited data in the Rif mountains are available for the Ketama and Tisiren units that represent the External Zones and Maghrebian Flysch domain, re- 0 spectively (Fig. 1B). The U-Pb crystallization ages from these domains are nearly identical to one another. The Taza-Guercif Basin samples contain U-Pb 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 crystallization age signatures that closely resemble those of the Rifean sam- Age (Ma) 326 12 ples (Fig. 5). The majority of U-Pb ages shared between the Rif samples and Taza-Guercif basin the Taza-Guercif Basin samples correspond to the Pan-African orogeny and (n=98) Probability West African cratonic signatures while the source of the shared Mesoprotero- 8 498 198 250 zoic population is poorly constrained. Given the commonality of the Pan-Afri- 4 can and West African craton ages across the region and the uncertainty of the

# of Grains temporal and spatial distribution of the Mesoproterozoic ages, this correlation 0 is insufficient to conclude a source-sink relationship.

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 Analysis of the ZFT cooling age distributions suggests that the sampled domains in the Rif are not the source for the Taza-Guercif Basin sediments (Fig. 5). Age (Ma) A combination of the ZFT cooling ages obtained in the Tisiren and Ketama Figure 6. Comparison of zircon fission-track spectra from the Rif and Middle units could provide the Variscan age distributions found in the Taza-Guercif Atlas samples of Pratt et al. (2015) to the Taza-Guercif Basin composite of Basin. However, both sampled Rif units lack the strong Triassic-centered cool- this study. ing age population that is ubiquitous in the Taza-Guercif Basin ZFT spectra. The Internal Zones of both the Rif and Betic mountains are equivalent The two successions also contain different cooling age distributions. The and composed of rocks from the allochthonous Alboran domain (Chalouan Bou Rached sandstones contain Ordovician–Silurian cooling peaks that are et al., 2008, and references therein). There are no comparable data for Internal absent in the Taza-Guercif Basin samples. Another difference is observed in Zones of the Rif (Fig. 1B); however, there are data for the Internal Zones of the the youngest cooling peaks in the Taza-Guercif Basin samples that are Triassic– Betic Mountains of Spain. Comparison of the zircon crystallization and cooling Early Jurassic in age, whereas those of the Bou Rached sandstones are Middle age data from the Betic Alboran domain (Platt and Whitehouse, 1999; Zeck Jurassic and Early Cretaceous. This difference is within the possible range of and Whitehouse, 1999, 2002; Zeck and Williams, 2001) and those of the Taza- error for individual grains as determined by the 95% confidence interval and Guercif Basin indicate that the Betic Alboran domain was not the source for the may reflect method and not geology. Taza-Guercif Basin. (1) The Taza-Guercif Basin sediments lack the Paleogene to While the Bou Rached sandstones are in closest proximity to the sam- early Miocene ZFT cooling age ages commonly recorded in the Alboran do- pled sediments of the Taza-Guercif Basin, the majority of the northern Middle main, although this may be a product of selection bias for radiation-damaged Atlas outcrops consist of the lower Jurassic Lias platform carbonates. These grains in our ZFT analysis. (2) The Variscan U-Pb crystallization ages that occur rocks are an unlikely source for detrital sediments in the Taza-Guercif Basin in abundance in the Internal domain are scant in the Taza-Guercif sediments as the dominant carbonate lithology is incapable of generating the coarser (Fig. 5). (3) The U-Pb zircon data from the Alboran domain lack the Meso arenaceous turbidites and transitional marine sandstones found within the proterozoic crystallization ages that occur in all Taza-Guercif samples.

Triassic-Centered Detrital Cooling Ages and Their Possible Sources Middle Atlas Source (?)

The Triassic cooling age population that is consistent in ZFT data across The U-Pb zircon crystallization age results of this study as well as those the Taza-Guercif Basin samples distinguish them from the available data in from previous Moroccan detrital-zircon studies (Abati et al., 2010; Avigad et al., the Bou Rached sandstones of the Middle Atlas as well as the Internal Zones, 2012; Pratt et al., 2015) suggest a similar U-Pb signature for the majority of Maghrebian Flysch domain, and External Zones of the Rif (Figs. 4 and 5; Pratt Moroccan stratigraphy, obscuring robust source-sink correlations using only et al., 2015). Even though the Bou Rached sandstones lack this key ZFT pop- detrital zircon U-Pb crystallization ages. As a result we primarily rely on our ulation, the most likely source for the Triassic cooling populations is other smaller (and larger error) ZFT cooling age data set, integrated with regional strata in the High and Middle Atlas mountains (Fig. 1B). Triassic extension geologic relationships, to interpret the provenance of the Taza-Guercif Ba- and rifting in the Tethyan domain formed the High and Middle Atlas rift basins sin stratigraphy. The ZFT data indicate that the currently sampled stratigra- (Frizon de Lamotte et al., 2008) and domains were marked by magmatism in phy of the Rif and Middle Atlas mountains is not the dominant source of the the Mesozoic. Taza-Guercif Basin sediments because they do not share the Triassic-centered Magmatic events that may be recorded in the ZFT ages include the Cen- cooling population. Therefore, despite the similar U-Pb zircon crystallization tral Atlantic Magmatic Province magmatism that affected Morocco and is re- age distributions between the Taza-Guercif Basin and the Rif (Pratt et al., 2015), stricted in age to between 200 and 196 Ma (Knight et al., 2004; Verati et al., we propose that the dominant zircon source to the Taza-Guercif Basin was the 2007). The cooling age population also encompasses two phases of Jurassic– lower Cretaceous continental successions of the Middle and High Atlas moun- Early Cretaceous magmatism that followed in the High Atlas at 175–155 Ma tains. This interpretation is based on five lines of reasoning. and 135–110 Ma (Souhel, 1996; Frizon de Lamotte et al., 2008). These ages 1. The age of at least part of the source stratigraphy should be the same could derive from either the High or Middle Atlas mountains. Triassic Central age or younger than the 150–125 Ma ZFT ages found in the basin as these Atlantic Magmatic Province–related magmatism occurred in both regions and grains are inherited from the sources. If these cooling ages were acquired in while only the High Atlas was affected directly by the Jurassic magmatism the source in situ, it is highly unlikely the older cooling ages would have been (Frizon de Lamotte et al., 2008), the Middle Atlas underwent coeval hydrother- retained. mal heating (Hamidi et al., 1997; Auajjar and Boulègue, 2002; Dekayir et al., 2. The Middle and High Atlas were the loci of Triassic–Jurassic extension 2005). These magmatic episodes are consistent with the range of ages present and associated magmatic and hydrothermal heating that are the inferred in the Triassic-centered cooling age population (Fig. 3), and the combination source of the corresponding Triassic–Jurassic cooling peak. of several events could explain the broad distribution of ages as seen in the 3. A Late Cretaceous transgression inundated the majority of Morocco, Taza-Guercif Basin composite (Fig. 6). burying older Middle and High Atlas stratigraphy that may have contained A source in the Middle and High Atlas domains is supported by the avail- more locally derived sediment containing the Early Jurassic zircon cooling able thermochronological data outside the Middle Atlas mountains that age signal. imply that Morocco was mostly subsiding during the Triassic–Early Jurassic 4. The Lias carbonates and the upper Cretaceous fine-grained lithologies and that regional exhumation is an unlikely cause of the cooling recorded are unlikely sediment sources for the coarse and zircon-rich sandstones sam- in the Triassic–Early Jurassic ZFT ages. The western Anti-Atlas and West- pled in the Taza-Guercif Basin. ern Meseta were located along the West Moroccan arch, the common rift 5. This model is consistent with observed paleocurrent indicators in the shoulder of Tethyan (Atlas) and Atlantic rifting (Frizon de Lamotte et al., 2008, El Rhirane turbidites that suggest a southern Middle Atlas source (Gomez 2009), and are the most likely terranes in Morocco to record Triassic–Early et al., 2000). Although now mostly preserved on the margins of the uplifted Jurassic exhumation. Atlas Mountains, these Early Cretaceous sandstones likely covered a much Temperature-time models constructed from apatite fission-track (AFT) data wider area in the Cretaceous and were subsequently eroded during the uplift of Variscan granitoids and metamorphic rocks within the Western Meseta pre- of the Atlas. These rocks, along with the Lias strata, supplied sediment to the dict cooling below 120 °C by ca. 300–250 Ma (Saddiqi et al., 2009; Barbero Taza-Guercif Basin, generating the marls that dominate the basin, as well as et al., 2011) and record subsidence and burial through the Triassic and Jurassic the intercalated turbidite sandstones within. that reached temperatures insufficient to reset the ZFT system (Ghorbal et al., 2008; Saddiqi et al., 2009). These data imply that the zircons within the Vari- scan and older rocks of the Western Meseta basement most likely retained Provenance Evolution their Variscan and older cooling ages. Variscan cooling ages are also retained in the central and western Anti-Atlas, confirmed by ca. 340–310 Ma ZFT ages Although the composite U-Pb crystallization age spectrum of the Taza- obtained from the Proterozoic basement that cooled steadily in the absence of Guercif Basin suggests a dominant Middle Atlas source of sediment for the regional exhumation (Sebti et al., 2009; Ruiz et al., 2011; Oukassou et al., 2013). Taza-Guercif Basin, the presence or absence of provenance shifts and trends in

the basin fill from opening to closure is pertinent to constraining the tectonic age distribution. ZFT cooling ages of the Gypsiferous Marl unit sample TGB6 severing of the Rifean Corridor. The following discussion explores the prove- generally coincide with that of the El Rhirane turbidite sample TGB12A, con- nance of each individual sample moving upsection. taining Mesozoic cooling ages represented by a KDE peak at 223 Ma and a The Ras el Ksar formation samples TGB1 and TGB14A, from the north and mixing model peak at 171 Ma, along with a large ca. 335 Ma Variscan peak in south of the basin, respectively, demonstrate at least a partial divergence in both the KDE and mixing model. These data suggest that the Gypsiferous Marl sediment provenance during deposition at the opening of the Taza-Guercif Ba- unit sandstones were derived from the same source region as the El Rhirane sin. Sample TGB1 from the Bab Stout area contains a Paleozoic U-Pb zircon and Tachrift turbidites. crystallization signature that accounts for 25% of single-grain ages within the U-Pb zircon crystallization age spectra from the upsection Kef ed Deba For- sample (the largest such signature in the Taza-Guercif Basin samples) and a mation sample TGB10 and the continental Bou Irhardaiene Formation sample younger Neoproterozoic peak than present in the other samples. The sample TGB7 show no significant changes from the Gypsiferous Marl sandstone. Both has the lowest percentage of Mesoproterozoic grains, lacking the Ectasian– TGB10 and TGB7 contain a tri-peaked Pan-African distribution, while the mag- Tonian (ca. 1300–900 Ma) peaks common to other Taza-Guercif Basin samples. nitudes of the Ectasian–Tonian and the Paleoproterozoic peaks vary slightly. These features indicate that the sample may have been partially sourced from This minor variance may be attributed to changing exposures in the source Middle Jurassic sandstones equivalent to the Bou Rached sandstones. These region, hydrodynamic sorting, or simple statistics of random grain selection. samples may also have sourced from the west through the Rifean Corridor, because the sample location for TGB1 is nearer to the paleoconnection with the Saiss basin (Fig. 1). The Ras el Ksar Formation sample TGB14A contains Implications for the Closure of the Rifean Corridor fewer grains with Paleozoic U-Pb crystallization ages than the average for the Taza-Guercif Basin samples, and contains the two-peaked Ectasian-Tonian (ca. Our crystallization and cooling age data from detrital zircons of the Taza- 1300–900 Ma) populations (Fig. 3), suggesting a provenance different from Guercif Basin suggest that there were no major shifts in provenance between that of the northern sample (TGB1). deposition of (1) the El Rhirane and Tachrift turbidites, deposited when the The stratigraphically upsection turbidite units of the Melloulou Formation basin reached its deepest bathymetry, and (2) the post-shallowing Gypsiferous (TGB3 and TGB12A) contain similar U-Pb crystallization age spectra, each con- Marl unit. Thus, the shallowing of the basin did not shift the source for the taining a Pan-African signature with a dominant peak ca. 615 Ma and a subor- Taza-Guercif Basin, and it continued to subside throughout the deposition of dinate peak ca. 534 Ma. The spectra differ in the older ages, yet the similarity is the thick Gypsiferous Marl unit. striking for ages younger than 700 Ma, and is not shared with any of the other The shallowing was most likely the result of a restricted marine connection Taza-Guercif Basin samples. The age of mixture model peaks generated for the to the west and/or the cessation of tectonic subsidence (Bernini et al., 1999; ZFT cooling age data are similar between the two units. Significant differences Gomez et al., 2000). Basin uplift associated with the advancement of the Rif occur only in the Mesozoic cooling populations, where the El Rhirane turbidite thrusts and olistostrome emplacement is an alternative explanation for the sample contains a peak in the Triassic and the Tachrift turbidite sample con- onset of shallowing (Krijgsman et al., 1999; Krijgsman and Langereis, 2000). tains a peak in the Early Jurassic. This degree of variation is within the 95% Detrital zircons from Taza-Guercif Basin strata deposited before and after shal- confidence interval of error for individual ZFT analyses and it is possible that lowing show no obvious provenance shifts in either the fission-track cooling these peaks represent the same population. The KDE peak ages for the ZFT ages or U-Pb crystallization ages that would suggest increased sediment sup- spectra are also similar between samples, sharing the Variscan peak and with ply accompanying uplift in the adjacent Rif mountains. The presence of the a Triassic peak for the El Rhirane unit and an Early Jurassic peak for the Tachrift Masgout and Tazzeka areas as basement highs along the Msoun arch (Gomez unit. The two Mesozoic peaks are within the 95% confidence interval of each et al., 2000; Sani et al., 2000) during the Neogene filling of the Taza-Guercif of the individual ages that compose the populations. Despite the differences in Basin may have prevented Rif sediments from penetrating the Melloulou- the proportions of each cooling population between the samples, they occur Zobzit embayment, particularly during the deposition of the Gypsiferous Marl at the same ages. This suggests that they were derived from the same general unit under shallow conditions. source region. The minor differences between the samples probably reflect The shift to an intracontinental basin ca. 6.7–6.0 Ma marked by the uncon- changes in the relative exposure of different rocks within the source area or a formity between the Kef ed Deba and Bou Irhardaiene Formations did not sig- modest shift in the locus of erosion. Paleocurrent indicators in the El Rhirane nificantly affect the detrital zircon U-Pb crystallization age distribution in the turbidites indicate a southern source (Bernini et al., 1999), consistent with ero- basin. The presence of the distinct tri-peaked Pan-African zircon crystallization sion of Middle Atlas or High Atlas Mesozoic cover. age signal in the Gypsiferous Marl, Kef ed Deba Formation, and Bou Irhar- Upsection in the post-shallowing Gypsiferous Marl unit of the Melloulou daiene Formation would not likely have been maintained across their bound- Formation, the U-Pb zircon crystallization age spectrum of sample TGB5 con- ing unconformities through a major shift in provenance. This implies that the tains Tonian- and Ectasian-age peaks and a distinctive tri-peaked Pan-African final emergence of the basin did not affect the provenance of basin sediments.

While the subsidence of the Taza-Guercif Basin was controlled by loading Taza-Guercif Basin received the majority of its sediment from a consistent from the Rif interacting with Middle Atlas structures and then sediment load- source, suggested here to be the Middle Atlas mountains to the south. ing (Bernini et al., 1999, 2000; Gomez et al., 2000; Sani et al., 2000), the avail- There is no indication of increased sedimentation from the Rif mountains ability of sediments that filled the basin appears to have been controlled by as they encroached upon the Rifean Corridor in the Messinian. This suggests the relative uplift of Middle Atlas mountains. Thus, an apparently consistent that the thermal and contractional uplift of the Middle Atlas played a role in source of sediments derived from the Middle Atlas agrees well with models isolating the Taza-Guercif Basin prior to the onset of the MSC in the Mediterra- for domal surface uplift of the region beginning ca. 15 Ma (Barbero et al., 2007; nean. With similar effects of Middle Atlas uplift documented in the Saiss basin Babault et al., 2008), with intermittent fault-controlled uplift providing coarse (Babault et al., 2008), across the Rif-Middle Atlas contact, uplift of the Middle turbidite sedimentation. Atlas may have contributed substantially to the closure of the Rifean Corridor. The role of thermal uplift of the Middle Atlas has also been proposed to contribute to the closing of the Saiss basin west of the Taza-Guercif Basin and the contact of the Rif and Middle Atlas mountains (Babault et al., 2008). The REFERENCES CITED Ras el Ksar Formation outcrop where TGB14A was collected now is at an ele- Abati, J., Aghzer, A.M., Gerdes, A., and Ennih, N., 2010, Detrital zircon ages of Neoproterozoic sequences of the Moroccan Anti-Atlas belt: Precambrian Research, v. 181, p. 115–128, doi:10 vation of ~580 m, ~260 m higher than the Ras el Ksar Formation outcrops in the .1016/j.precamres.2010.05.018. north of the basin where TGB1 was collected. Today, the northern Middle Atlas Agustí, J., Garcés, M., and Krijgsman, W., 2006, Evidence for African-Iberian exchanges during mountains drain to the north through the old Taza-Guercif Basin depocenter, the Messinian in the Spanish mammalian record: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 238, p. 5–14, doi:10.1016/j.palaeo.2006.03.013. a scenario that seems relatively unchanged since the Neogene opening of the Auajjar, J., and Boulègue, J., 2002, Dolomites in the Tazekka Pb-Zn district, eastern Morocco: Taza-Guercif Basin. Polyphase origin from hydrothermal fluids: Terra Nova, v. 14, p. 175–182, doi:10.1046 /j .1365 -3121.2002.00405.x. Avigad, D., Gerdes, A., Morag, N., and Bechstädt, T., 2012, Coupled U-Pb-Hf of detrital zircons of Cambrian sandstones from Morocco and Sardinia: Implications for provenance and Pre- CONCLUSIONS cambrian crustal evolution of North Africa: Gondwana Research, v. 21, p. 690–703, doi:10 .1016/j.gr.2011.06.005. Our analysis of the detrital zircon in the Taza-Guercif Basin provides the Babault, J., Teixell, A., Arboleya, M.L., and Charroud, M., 2008, A late Cenozoic age for long-wave- length surface uplift of the Atlas Mountains of Morocco: Terra Nova, v. 20, p. 102–107, doi:10 first attempt to constrain the provenance of the basin sediments under the .1111/j.1365-3121.2008.00794.x. dual tectonic influence of the Rif and Middle Atlas mountains to elucidate Barbero, L., Teixell, A., Arboleya, M.L., Río, P.D., Reiners, P.W., and Bougadir, B., 2007, Juras- the forces that severed the Rifean Corridor. The conclusions from this analy- sic-to-present thermal history of the central High Atlas (Morocco) assessed by low-temperature thermochronology: Terra Nova, v. 19, p. 58–64. sis follow. Barbero, L., Jabaloy, A., Gómez-Ortiz, D., Pérez-Peña, J.V., Rodríguez-Peces, M.J., Tejero, R., Estu Inherited Triassic-centered ZFT cooling ages present in all of the Taza- piñán, J., Azdimousa, A., Vázquez, M., and Asebriy, L., 2011, Evidence for surface uplift of the Guercif Basin samples indicate that the primary source for the basin derived Atlas Mountains and the surrounding peripheral plateaux: Combining apatite fission-track results and geomorphic indicators in the Western Moroccan Meseta (coastal Variscan Paleo- from the post-Jurassic cover of the Middle and/or High Atlas mountains, the zoic basement): Tectonophysics, v. 502, p. 90–104, doi:10.1016/j.tecto.2010.01.005. proximal position of the former offering a more likely match. Bernet, M., and Garver, J.I., 2005, Fission-track analysis of detrital zircon, in Reiners, P.W., and Ehlers, The sediment provenance at the opening of the Taza-Guercif Basin was not T.A., eds., Low-temperature thermochronology: Techniques, interpretations, and applications: Reviews in Mineralogy and Geochemistry Volume 58, p. 205–237, doi:10 .2138 /rmg .2005 .58.8 . uniform across the basin. The northern Ras el Ksar Formation contains signif- Bernini, M., Boccaletti, M., Gelati, R., Moratti, G., Papani, G., and El Mokhtari, J., 1999, Tectonics icant zircons with crystallization ages between 500 and 400 Ma, a population and sedimentation in the Taza-Guercif Basin, northern Morocco: Implications for the Neo- found in the Middle Jurassic sandstones of the Middle Atlas (Pratt et al., 2015), gene evolution of the Rif-Middle Atlas orogenic system: Journal of Petroleum Geology, v. 22, p. 115–128, doi:10.1111/j.1747-5457.1999.tb00462.x. while the southern Ras el Ksar Formation contains a provenance signal similar Bernini, M., Boccaletti, M., Moratti, G., and Papani, G., 2000, Structural development of the Taza- to that throughout the rest of the basin fill. Guercif Basin as a constraint for the Middle Atlas shear zone tectonic evolution: Marine and The turbidites of the overlying Melloulou Formation differ slightly from one Petroleum Geology, v. 17, p. 391–408, doi:10.1016/S0264-8172(99)00042-2. 206 238 another but both reflect an overall Middle Atlas provenance. Variations may Black, L.P., et al., 2004, Improved Pb/ U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope have resulted from minor shifts in the locus of erosion or changes in the rel- documentation for a series of zircon standards: Chemical Geology, v. 205, p. 115–140, doi:10 ative exposure of different source rocks. These changes may reflect tectonic .1016/j.chemgeo.2004.01.003. activity in the Middle Atlas, a scenario that has been previously proposed (Ber- Braga, J.C., Martín, J.M., Riding, R., Aguirre, J., Sánchez-Almazo, I.M., and Dinarès-Turell, J., 2006, Testing models for the Messinian salinity crisis: The Messinian record in Almería, SE nini et al., 1999; Gelati et al., 2000). Spain: Sedimentary Geology, v. 188, p. 131–154, doi:10.1016/j.sedgeo.2006.03.002. Sediment provenance did not change with the deposition of the Gypsif- Brandon, M.T., 1996, Probability density plot for fission-track grain-age samples: Radiation Mea- erous Marl unit after rapid shallowing of the Taza-Guercif Basin and Rifean surements, v. 26, p. 663–676, doi:10.1016/S1350-4487(97)82880-6. Chalouan, A., Michard, A., El Kadiri, K., Negro, F., de Lamotte, D.F., Soto, J.I., and Saddiqi, O., Corridor. The U-Pb zircon crystallization age spectra do not differ significantly 2008, The Rif Belt, in Michard, A., Saddiqi, O., Chalouan, A., and Frizon de Lamotte, D., onward through the Pliocene Bou Irhardaiene Formation, suggesting that the eds., Continental Evolution: The Geology of Morocco: Berlin, German, Springer, p. 203–302.

Cornée, J.J., et al., 2014, The early Pliocene reflooding in the western Mediterranean: New in- Jolivet, L., Augier, R., Robin, C., Suc, J.P., and Rouchy, J.M., 2006, Lithospheric-scale geodynamic sights from the rias of the Internal Rif, Morocco: Comptes Rendus Geoscience, v. 346, no. 3, context of the Messinian salinity crisis: Sedimentary Geology, v. 188, p. 9–33, doi:10 .1016 /j p. 90–98, doi:10.1016/j.crte.2014.03.002. .sedgeo.2006.02.004. Dekayir, A., Amouric, M., and Olives, J., 2005, Clay minerals in hydrothermally altered basalts Knight, K.B., Nomade, S., Renne, P.R., Marzoli, A., Bertrand, H., and Youbi, N., 2004, The Central from Middle Atlas, Morocco: Clay Minerals, v. 40, p. 67–77, doi:10 .1180 /0009855054010156 . Atlantic Magmatic Province at the Triassic-Jurassic boundary: Paleomagnetic and 40Ar/39Ar Duggen, S., Hoernle, K., Van Den Bogaard, P., Rüpke, L., and Morgan, J.P., 2003, Deep roots of evidence from Morocco for brief, episodic volcanism: Earth and Planetary Science Letters, the Messinian salinity crisis: Nature, v. 422, no. 6932, p. 602–606, doi:10 .1038 /nature01553 . v. 228, p. 143–160, doi:10.1016/j.epsl.2004.09.022. Duggen, S., Hoernle, K., van den Bogaard, P., and Harris, C., 2004, Magmatic evolution of the Krijgsman, W., and Langereis, C.G., 2000, Magnetostratigraphy of the Zobzit and Koudiat Zarga Alboran region: The role of subduction in forming the western Mediterranean and causing sections (Taza-Guercif basin, Morocco): Implications for the evolution of the Rifian Corridor: the Messinian Salinity Crisis: Earth and Planetary Science Letters, v. 218, p. 91–108, doi:10 Marine and Petroleum Geology, v. 17, p. 359–371. .1016/S0012-821X(03)00632-0. Krijgsman, W., Langereis, C.G., Zachariasse, W.J., Boccaletti, M., Moratti, G., Gelati, R., Iaccarino, Duggen, S., Hoernle, K., van den Bogaard, P., and Garbe-Schönberg, D., 2005, Post-collisional S., Papani, G., and Villa, G., 1999a, Late Neogene evolution of the Taza-Guercif Basin (Rifean transition from subduction- to intraplate-type magmatism in the westernmost Mediterra- Corridor, Morocco) and implications for the Messinian salinity crisis: Marine Geology, v. 153, nean: Evidence for continental-edge delamination of subcontinental lithosphere: Journal of p. 147–160, doi:10.1016/S0025-3227(98)00084-X. Petrology, v. 46, p. 1155–1201, doi:10.1093/petrology/egi013. Krijgsman, W., Hilgen, F.J., Raffi, I., Sierro, F.J., and Wilson, D.S., 1999b, Chronology, causes and pro- Faure-Muret, A., and Choubert, G., 1971, Le Maroc. Domaine rifain et atlasique, in Tectonique de gression of the Messinian salinity crisis: Nature, v. 400, no. 6745, p. 652–655, doi:10.1038 /23231 . l’Afrique: Paris, United Nations Educational, Scientific and Cultural Organization, p. 17–46. Linnemann, U., Ouzegane, K., Drareni, A., Hofmann, M., Becker, S., Gärtner, A., and Sagawe, A., Fleischer, R.L., Price, P.B., and Walker, R.M., eds., 1975, Nuclear Tracks in Solids: Principles and 2011, Sands of West Gondwana: An archive of secular magmatism and plate interactions—A Applications: Berkeley, University of California Press, 626 p. case study from the Cambro-Ordovician section of the Tassili Ouan Ahaggar (Algerian Frizon de Lamotte, D.F., Zizi, M., Missenard, Y., Hafid, M., El Azzouzi, M., Maury, R.C., Char- Sahara) using U-Pb-LA-ICP-MS detrital zircon ages: Lithos, v. 123, p. 188–203, doi:10.1016 /j rière, A., Taki, Z., Benammi, M., and Michard, A., 2008, The Atlas system, in Michard, A., .lithos.2011.01.010. et al., eds., Continental evolution: The geology of Morocco: Heidelberg, Berlin, Springer, Lofi, J., Deverchère, J., Gaullier, V., Gillet, H., Guennoc, P., Gorini, C., Loncke, L., Maillard, A., p. 133–202. Sage, F., and Thinon, I., 2011, Seismic atlas of the Messinian salinity crisis markers in the Frizon de Lamotte, D., Leturmy, P., Missenard, Y., Khomsi, S., Ruiz, G., Saddiqi, O., Guillocheau, offshore Mediterranean domain: Commission de la Carte Géologique du Monde and Société F., and Michard, A., 2009, Mesozoic and Cenozoic vertical movements in the Atlas system Géologique de France, 72 p. (Algeria, Morocco, Tunisia): An overview: Tectonophysics, v. 475, p. 9–28, doi:10 .1016 /j .tecto Michard, A., Hoepffner, A., Soulaimana, A., and Baidder, L., 2008, The Variscan Belt, in Michard, .2008.10.024. A., et al., eds., Continental evolution: The geology of Morocco: Structure, stratigraphy, and Garcés, M., Krijgsman, W., and Agustí, J., 2001, Chronostratigraphic framework and evolution of tectonics of the Africa-Atlantic-Mediterranean triple junction: Lecture Notes in Earth Sci- the Fortuna basin (Eastern Betics) since the late Miocene: Basin Research, v. 13, p. 199–216, ences Volume 116: Berlin, Springer, p. 65–132, doi:10.1007/978-3-540-77076-3_3. doi:10.1046/j.1365-2117.2001.00144.x. Montario, M.J., and Garver, J.I., 2009, The thermal evolution of the Grenville terrane revealed Garcia-Castellanos, D., Estrada, F., Jiménez-Munt, I., Gorini, C., Fernández, M., Vergés, J., and De through U-Pb and fission-track analysis of detrital zircon from Cambro-Ordovician quartz Vicente, R., 2009, Catastrophic flood of the Mediterranean after the Messinian salinity crisis: arenites of the Potsdam and Galway Formations: Journal of Geology, v. 117, p. 595–614, doi: Nature, v. 462, p. 778–781. 10.1086/605778. Gehrels, G.E., Valencia, V.A., and Ruiz, J., 2008, Enhanced precision, accuracy, efficiency, Murphy, L.N., Kirk-Davidoff, D.B., Mahowald, N., and Otto-Bliesner, B.L., 2009, A numerical study and spatial resolution of U-Pb ages by laser ablation–multicollector–inductively coupled of the climate response to lowered Mediterranean Sea level during the Messinian Salinity plasma–mass spectrometry: Geochemistry, Geophysics, Geosystems, v. 9, Q03017, doi:10 Crisis: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 279, p. 41–59, doi:10 .1016/j .1029/2007GC001805. .palaeo.2009.04.016. Gelati, R., Moratti, G., and Papani, G., 2000, The late Cenozoic sedimentary succession of the Naeser, C.W., 1979, Fission-track dating and geologic annealing of fission tracks, in Jäeger, C., Taza-Guercif Basin, South Rifean Corridor, Morocco: Marine and Petroleum Geology, v. 17, and Hunziker, J.C., eds., Lectures in isotope geology: Berlin, Heidelberg, Springer, p. 154– p. 373–390, doi:10.1016/S0264-8172(99)00054-9. 169, doi:10.1007/978-3-642-67161-6_10. Ghorbal, B., Bertotti, G., Foeken, J., and Andriessen, P., 2008, Unexpected Jurassic to Neogene Nance, R.D., and Murphy, J.B., 1994, Contrasting basement isotopic signatures and the palin- vertical movements in ‘stable’ parts of NW Africa revealed by low temperature geochronol- spastic restoration of peripheral orogens: Example from the Neoproterozoic Avalonian- ogy: Terra Nova, v. 20, p. 355–363, doi:10.1111/j.1365-3121.2008.00828.x. Cadomian belt: Geology, v. 22, p. 617–620. Gomez, F., Barazangi, M., and Demnati, A., 2000, Structure and evolution of the Neogene Guercif Oukassou, M., Saddiqi, O., Barbarand, J., Sebti, S., Baidder, L., and Michard, A., 2013, Post- Basin at the junction of the Middle Atlas Mountains and the Rif thrust belt, Morocco: Ameri- Variscan exhumation of the Central Anti-Atlas (Morocco) constrained by zircon and apatite can Association of Petroleum Geologists Bulletin, v. 84, p. 1340–1364, doi:10 .1306 /A9673EA0 fission-track thermochronology: Terra Nova, v. 25, p. 151–159, doi:10 .1111 /ter.12019. -1738-11D7-8645000102C1865D. Paton, C., Hellstrom, J., Paul, B., Woodhead, J., and Hergt, J., 2011, Iolite: Freeware for the visual- Hamidi, E.M., Boulangé, B., and Colin, F., 1997, Altération d’un basalte triasique de la région isation and processing of mass spectrometric data: Journal of Analytical Atomic Spectrom- d’Elhajeb, Moyen Atlas, Maroc: Journal of African Earth Sciences, v. 24, p. 141–151, doi:10 etry, v. 26, p. 2508–2518, doi:10 .1039 /c1ja10172b . .1016/S0899-5362(97)00032-8. Pérez-Asensio, J.N., Aguirre, J., Jiménez-Moreno, G., Schmiedl, G., and Civis, J., 2013, Glacio- Hodell, D.A., Benson, R.H., Kennett, J.P., and Bied, R.E., 1989, Stable isotope stratigraphy of latest eustatic control on the origin and cessation of the Messinian salinity crisis: Global and Plan- Miocene sequences in northwest Morocco: The Bou Regreg section: Paleoceanography, v. 4, etary Change, v. 111, p. 1–8, doi:10.1016/j.gloplacha.2013.08.008. p. 467–482, doi:10.1029/PA004i004p00467. Platt, J.P., and Whitehouse, M.J., 1999, Early Miocene high-temperature metamorphism and Hodell, D.A., Benson, R.H., Kent, D.V., Boersma, A., and Bied, R.E., 1994, Magnetostratigraphic, rapid exhumation in the Betic Cordillera (Spain): Evidence from U-Pb zircon ages: Earth and biostratigraphic, and stable isotope stratigraphy of an Upper Miocene drill core from the Planetary Science Letters, v. 171, p. 591–605, doi:10.1016/S0012-821X(99)00176-4. Salé Briqueterie (northwestern Morocco): A high-resolution chronology for the Messinian Pratt, J.R., Barbeau, D.L., Jr., Garver, J.I., Emran, A., and Izykowski, T.M., 2015, Detrital zircon stage: Paleoceanography, v. 9, p. 835–855, doi:10.1029 /94PA01838 . geochronology of Mesozoic sediments in the Rif and Middle Atlas Belts of Morocco: Prove- Hsü, K.J., Ryan, W.B.F., and Cita, M.B., 1973, Late Miocene desiccation of the Mediterranean: nance constraints and refinement of the West African signature: Journal of Geology, v. 123, Nature, v. 242, no. 5395, p. 240–244, doi:10 .1038 /242240a0 . p. 177–200, doi:10.1086/681218. Hsü, K.J., Montadert, L., Bernoulli, D., Cita, M.B., Erickson, A., Garrison, R.E., Kidd, F., Müller, C., Rouchy, J., and Caruso, A., 2006, The Messinian salinity crisis in the Mediterranean basin: A and Wright, R., 1977, History of the Mediterranean salinity crisis: Nature, v. 267, no. 5610, reassessment of the data and an integrated scenario: Sedimentary Geology, v. 188–189, p. 399–403, doi:10.1038/267399a0. p. 35–67, doi:10.1016/j.sedgeo.2006.02.005.

Roveri, M., et al., 2014, The Messinian Salinity Crisis: Past and future of a great challenge for Tagami, T., and O’Sullivan, P.B., 2005, Fundamentals of fission-track thermochronology: Reviews marine sciences: Marine Geology, v. 352, p. 25–58, doi:10.1016/j.margeo.2014.02.002. in Mineralogy and Geochemistry, v. 58, p. 19–47. Ruiz, G.M.H., Sebti, S., Negro, F., Saddiqi, O., Frizon de Lamotte, D., Stockli, D., Foeken, J., Stuart, Teixell, A., Ayarza, P., Zeyen, H., Fernandez, M., and Arboleya, M.L., 2005, Effects of mantle upwell- F., Barbarand, J., and Schaer, J.P., 2011, From central Atlantic continental rift to Neogene ing in a compressional setting: The Atlas Mountains of Morocco: Terra Nova, v. 17, p. 456–461. uplift–western Anti-Atlas (Morocco): Terra Nova, v. 23, p. 35–41, doi:10.1111 /j.1365-3121 .2010 Thomas, M.F.H., Bodin, S., Redfern, J., and Irving, D.H.B., 2010, A constrained African craton source .00980.x. for the Cenozoic Numidian Flysch: Implications for the palaeogeography of the western Med- Saddiqi, O., El Haimer, F.Z., Michard, A., Barbarand, J., Ruiz, G.M.H., Mansour, E.M., Leturmy, P., iterranean basin: Earth-Science Reviews, v. 101, p. 1–23, doi:10 .1016 /j .earscirev .2010 .03 .003 . and Frizon De Lamotte, D., 2009, Apatite fission-track analyses on basement granites from Verati, C., Rapaille, C., Féraud, G., Marzoli, A., Bertrand, H., and Youbi, N., 2007, 40Ar/39Ar ages and south-western Meseta, Morocco: Paleogeographic implications and interpretation of AFT duration of the Central Atlantic Magmatic Province volcanism in Morocco and Portugal and age discrepancies: Tectonophysics, v. 475, p. 29–37, doi:10.1016/j.tecto.2009.01.007. its relation to the Triassic-Jurassic boundary: Palaeogeography, Palaeoclimatology, Palaeo- Sani, F., Zizi, M., and Bally, A.W., 2000, The Neogene–Quaternary evolution of the Guercif Basin ecology, v. 244, p. 308–325, doi:10.1016/j.palaeo.2006.06.033. (Morocco) reconstructed from seismic line interpretation: Marine and Petroleum Geology, Vermeesch, P., 2009, RadialPlotter: A Java application for fission track, luminescence and other v. 17, p. 343–357, doi:10.1016/S0264-8172(99)00058-6. radial plots: Radiation Measurements, v. 44, p. 409–410, doi:10.1016/j.radmeas.2009.05.003. Sebti, S., Saddiqi, O., El Haimer, F.Z., Michard, A., Ruiz, G., Bousquet, R., Baidder, L., and Frizon Vermeesch, P., 2012, On the visualisation of detrital age distributions: Chemical Geology, v. 312, de Lamotte, D., 2009, Vertical movements at the fringe of the West African Craton: First p. 190–194, doi:10.1016/j.chemgeo.2012.04.021. zircon fission track datings from the Anti-Atlas Precambrian basement, Morocco: Comptes Warny, S.A., Bart, P.J., and Suc, J.P., 2003, Timing and progression of climatic, tectonic and Rendus Geoscience, v. 341, p. 71–77, doi:10.1016/j.crte.2008.11.006. glacioeustatic influences on the Messinian Salinity Crisis: Palaeogeography, Palaeoclimatol- Sissingh, W., 2008, Punctuated Neogene tectonics and stratigraphy of the African-Iberian ogy, Palaeoecology, v. 202, p. 59–66, doi:10.1016/S0031-0182(03)00615-1. plate-boundary zone: Concurrent development of Betic-Rif basins (southern Spain, northern Zeck, H.P., and Whitehouse, M.J., 1999, Hercynian, Pan-African, Proterozoic and Archean ion- Morocco): Geologie en Mijnbouw, v. 87, p. 241–289. microprobe zircon ages for a Betic-Rif core complex, Alpine belt, W Mediterranean—Conse- Souhel, A., 1996, Le mésozoïque dans le haut-atlas de Béni-Mellal (Maroc): Stratigraphie, sédi- quences for its PTt path: Contributions to Mineralogy and Petrology, v. 134, p. 134–149, doi: mentologie et évolution géodynamique [Ph.D. thesis]: Toulouse, France, Université Paul 10.1007/s004100050474. Sabatier, 249 p. Zeck, H.P., and Whitehouse, M.J., 2002, Repeated age resetting in zircons from Hercynian–Alpine Stern, R.J., 2002, Crustal evolution in the East African orogen: A neodymium isotopic perspec- polymetamorphic schists (Betic-Rif tectonic belt, S. Spain)—A U-Th-Pb ion microprobe tive: Journal of African Earth Sciences, v. 34, p. 109–117, doi:10.1016 /S0899 -5362(02)00012-X. study: Chemical Geology, v. 182, p. 275–292, doi:10.1016/S0009-2541(01)00296-0. Stern, R.J., 1994, Arc-assembly and continental collision in the Neoproterozoic African orogen: Zeck, H.P., and Williams, I.S., 2001, Hercynian metamorphism in nappe core complexes of the Implications for the consolidation of Gondwanaland: Annual Review of Earth and Planetary Alpine Betic-Rif belt, western Mediterranean—A SHRIMP zircon study: Journal of Petrology, Sciences, v. 22, p. 319–351, doi:10.1146/annurev.ea.22.050194.001535. v. 42, p. 1373–1385, doi:10.1093/petrology/42.7.1373.