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Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria)

DOI: 10.1111/bre.12182

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Citation for published version (APA): English, K., Redfern, J., Bertotti, G., English, J. M., & Yahia Cherif, R. (2016). Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria). Basin Research, 1. https://doi.org/10.1111/bre.12182

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1 2 3 4 1 Cenozoic uplift of the Hoggar Region, North Africa: constraints from its 5 6 2 northern flank (Illizi basin, Algeria) 7 8 9 3 Kara L. English 10 4 Petroceltic International Plc, 5th Floor, 3 Grand Canal Plaza, Grand Canal Street Upper, Dublin 11 12 5 4, Ireland. Phone: +353 1 421 8300; E-mail: [email protected] 13 14 6 Jonathan Redfern 15 16 7 School of Earth, Atmospheric and Environmental Sciences, University of Manchester, 17 18 8 Williamson Building, Oxford Road, Manchester, M13 9PL, United Kingdom; E-mail: 19 20 9 [email protected] 21 22 10 Giovanni Bertotti 23 24 11 Geoscience and Engineering, Delft University of Technology, Stevinweg 1, 2628CN, Delft, The 25 26 12 Netherlands; E-mail: [email protected] 27 28 13 Joseph M. English 29 th 30 14 Petroceltic International Plc, 5 Floor, 3 Grand Canal Plaza, Grand Canal Street Upper, Dublin 31 15 4, Ireland. Phone: +353 1 421 8300; E-mail: [email protected] 32 33 34 16 Rachida Yahia Cherif 35 17 Direction Coordination Groupe Associations – Sonatrach, Djenane El-Malik, Hydra, Alger, 36 37 18 Algérie (Algeria); E-mail: [email protected] 38 39 40 19 Submitted to Basin Research, July 27th, 2015 41 42 20 Revision submitted to Basin Research, November 13, 2015 43 44 21 Second Revision submitted to Basin Research, January 3, 2016 45 22 Main text word count = 5960 46 47 23 Abstract word count = 182 48 49 24 Number of references = 85 50 51 25 Number of tables = 3 52 26 Number of figures = 7 53 54 27 Data Repository = Yes 55 56 28 Corresponding author = Kara English 57 58 1 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 2 of 41

1 2 3 29 ABSTRACT 4 5 30 Zones of anomalously high topography within continental interiors, distant from active plate 6 7 31 boundaries, are interpreted as being either dynamically supported by viscous flow in the 8 9 32 underlying mantle or influenced by plate tectonics. Constraining the models of their genesis 10 11 33 requires accurate data on the timing and dimensions of such features. New apatite fission-track 12 34 and thermal maturity data from the Illizi Basin in Algeria quantifies the magnitude and timing of 13 14 35 kilometre-scale uplift and exhumation of the northern flank of the Hoggar swell in North Africa. 15 16 36 The findings of this study, integrated with previously published thermochronological data, 17 18 37 confirm that long wavelength regional uplift occurred during the Cenozoic extending over a 19 38 distance in excess of 1,500 km from north to south. The uplift evidenced in the Hoggar Massif 20 21 39 significantly impacted the flanking Illizi and Tim Mersoï basins. The combination of thermal 22 23 40 history modelling and regional stratigraphic observations indicates that the onset of exhumation 24 25 41 of the Illizi Basin likely occurred during the Eocene, broadly coincident with magmatism on the 26 42 Hoggar Massif to the south and the onset of tectonic shortening in the Atlasic belt to the north. 27 28 29 43 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 2 59 60 FOR REVIEW PURPOSES ONLY Page 3 of 41 Basin Research

1 2 3 44 INTRODUCTION 4 5 6 45 Zones of anomalously high topography within continental interiors, far away from active 7 46 plate boundaries, are often interpreted as being dynamically supported by viscous flow in the 8 9 47 underlying mantle (e.g. Braun, 2010; Al-Hajri et al., 2009; Moucha & Forte, 2011; Jones et al., 10 11 48 2012). The average diameter of modern topographic swells across Africa and Antarctica is 1850 12 13 49 ± 450 km, and associated gravity anomalies suggest that the full height of dynamically supported 14 15 50 topography ranges from 800 to 1800 m (Jones et al., 2012). Long-wavelength basins and swells 16 51 characterize the present-day topography of Africa (Holmes, 1944; Burke, 1996). Northern Africa 17 18 52 is characterised by a number of prominent topographic swells, typically associated with 19 20 53 relatively young (c. 35 Ma-Recent) volcanism (e.g. Hoggar, Tibesti, Darfur; Fig. 1), consistent 21 22 54 with the involvement of sublithospheric processes (Sahagian, 1988; Wilson & Guiraud, 1992; 23 55 Burke, 1996; Liégeois et al., 2005; Azzouni-Sekkal et al., 2007; Beccaluva et al., 2007). 24 25 26 56 There is general consensus that mantle convection plays an important role in the formation 27 28 57 of many modern topographic swells, but detailed surface studies are required to establish the 29 58 timing and evolution of these uplifts in the geological record to provide constraints for 30 31 59 understanding their genesis. The Hoggar Massif in central North Africa (Fig. 1) is characterized 32 33 60 by exposed crystalline basement, and flanked by sedimentary basins. New apatite fission-track 34 35 61 and thermal maturity data from a well in the Illizi Basin (Well A; Fig. 1), along with basin 36 62 modelling and regional stratigraphic correlations, constrain both the timing and magnitude of 37 38 63 exhumation of the northern flank of the Hoggar Massif. These new data are integrated with 39 40 64 previously published thermochronological data from the Hoggar Massif and surrounding basins. 41 42 65 A regional cross-section is constructed from the Illizi and Berkine basins in the north, over the 43 66 Hoggar Massif, and southward across the Tim Mersoï and Iullemmeden basins (Fig. 1). This 44 45 67 illustrates that the Cenozoic kilometric-scale rock uplift occurred over a distance in excess of 46 47 68 1,500 km from north to south. 48 49 69 50 51 52 70 GEOLOGICAL SETTING 53 54 71 The Hoggar Massif in Algeria is associated with exposed Pan-African basement extending 55 2 56 72 over an area greater than 400,000 km (Fig. 1). The preserved Paleozoic sections north and south 57 58 3 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 4 of 41

1 2 3 73 of the Hoggar Massif have broadly similar stratigraphy, with up to 2.5 km of sedimentary section 4 5 74 preserved in the Illizi Basin (Galeazzi et al., 2010) to the north and in the Iullemmeden and Tim 6 7 75 Mersoï basins (Zanguina et al., 1998) to the south. A predominance of northerly paleocurrent 8 9 76 directions reported within Cambro-Ordovician and Devonian sandstones on the northern and 10 11 77 southern sides of the Hoggar Massif (Beuf et al., 1971) suggests that the Hoggar Massif was not 12 78 a structural high during the earlier part of the Paleozoic, and that sequences were originally 13 14 79 deposited continuously across the Hoggar region. Following the collision of Gondwana with 15 16 80 Laurasia, the Paleozoic sequence was variably uplifted and eroded across parts of northwest 17 18 81 Africa during the Late Carboniferous-Early Permian Hercynian (Variscan) Orogeny (Aliev et al., 19 82 1971; Burollet et al., 1978; Boote et al., 1998; Acheche et al., 2001). 20 21 22 83 Rifting along the northern margin of the African plate during the Early Triassic records the 23 84 initial breakup of Gondwana and the opening of the Tethyan seaway (e.g., Guiraud, 1998). 24 25 85 Triassic continental clastic systems sourced from uplifted Hercynian highs, flowed north- 26 27 86 northeast through the Berkine Basin towards the peri-Tethys (Turner et al., 2001). In response to 28 29 87 relative sea-level rise during the Middle Triassic, marine incursion occurred across Algeria, 30 31 88 Tunisia and western Libya leading to the formation of a restricted Triassic salt basin (Turner & 32 89 Sherif, 2007) in the northern portion of the Berkine and Oued Mya basins. Continued landward 33 34 90 encroachment during the Late Triassic and Early Jurassic resulted in the progressive southward 35 36 91 onlap of these successions onto older Paleozoic strata in the Illizi Basin (Galeazzi et al., 2010). 37 38 92 On the southern flank of the Hoggar Massif, the Iullemmeden Basin was also a site of 39 93 continental deposition during this time (Zanguina et al., 1998). 40 41 42 94 Some interpretations consider that the Hoggar Massif remained an exposed high since the 43 95 Hercynian orogeny until present-day (Fabre, 1976; Guiraud et al., 2005; Liégeois et al., 2005) 44 45 96 while others interpret that deposition may have occurred over the Hoggar Massif during the Late 46 47 97 Cretaceous–Early Eocene (Swezey, 2009; Rougier et al., 2013). Evidence to support the latter 48 49 98 interpretation are remnants of Jurassic to Cretaceous sediments that are widely preserved on the 50 51 99 flanks of the uplifted Hoggar Massif. In the Serouenout area of northeastern Hoggar (Fig. 1), up 52 100 to 350 m of poorly dated Upper Jurassic to Lower Cretaceous continental sandstones were 53 54 101 deposited directly on basement (Bordet, 1954; Philippe et al., 2003). The Serouenout sediments 55 2 56 102 cover an area of ~6,000 km with no indications of the basin limit (LeFranc & Guiraud, 1990). In 57 58 4 59 60 FOR REVIEW PURPOSES ONLY Page 5 of 41 Basin Research

1 2 3 103 the Amguid area in the northern Hoggar (Fig. 1), Upper Cenomanian-Lower Turonian limestones 4 5 104 unconformably overlie basement (Busson et al., 1999). These outcrops lie along trend from the 6 7 105 basement-controlled north-south oriented Amguid-El Biod High to the north (Fig. 1). This 8 9 106 structure was the site of major transpressional deformation during the Late Neocomian-Middle 10 11 107 Aptian Austrian event (Galeazzi et al., 2010), and the presence of the Amguid limestones 12 108 indicates at least partial inundation of this high during the Late Cretaceous. The short-lived 13 14 109 Austrian tectonic event was characterized by strike-slip deformation along major intra-plate 15 16 110 basement structures in North Africa, and was likely associated with the break-up of the 17 18 111 Equatorial Atlantic and rifting in Central Africa (Guiraud et al., 2005; Galeazzi et al., 2010). 19 20 112 In general, the Cenozoic stratigraphy of the Sahara records a transition from early Cenozoic 21 22 113 carbonate deposition to late Cenozoic siliciclastic deposition (Swezey, 2009). North of the 23 114 Hoggar, outcrops of marine carbonates in the Tademaït region (Fig. 1) record deposition during 24 25 115 the Late Cretaceous to Early Eocene. This sequence is capped by an unconformity, which is 26 27 116 locally overlain by either Upper Eocene-Oligocene fluvial sandstones or Miocene-Pliocene 28 29 117 fluvial sandstones and conglomerates (Swezey, 2009). In the Iullemmeden Basin, latest 30 31 118 Paleocene to Eocene marine deposits are capped by continental Eocene to Miocene deposits; 32 119 these sequences are separated by unconformities typically assigned to the Late Paleocene and 33 34 120 Late Eocene-Oligocene (Kogbe, 1981; Burke & Gunnell, 2008). Clastic deposits of Late Eocene- 35 36 121 Pliocene age in the Saharan region are collectively referred to as the “Continental Terminal” 37 38 122 (Kilian, 1931; Lang et al., 1990). Magmatic activity in the Hoggar area began at the Eocene- 39 123 Oligocene boundary (~34 Ma) and has continued until the present (Girod, 1971; Aït Hamou et 40 41 124 al., 2000; Liégeois et al., 2005; Azzouni-Sekkal et al., 2007). 42 43 125 44 45 46 126 PREVIOUS STUDIES OF HOGGAR UPLIFT 47 48 127 Evidence of rock uplift, defined as vertical displacement of rock compared to a fixed frame 49 50 128 of reference (England & Molnar, 1990), is observed in the core of the Hoggar, where the 51 52 129 Precambrian basement attains average elevations of 1,000-1,500 m a.s.l. (Lesquer et al., 1990), 53 130 while locally reaching elevations of ~2,400 m a.s.l. in the Atakor region (Fig. 1) (Girod, 1971). 54 55 131 The Upper Jurassic to Lower Cretaceous sandstones at Serouenout mostly occur at elevations 56 57 58 5 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 6 of 41

1 2 3 132 between 1,200 and 1,400 m a.s.l., although they can reach up to 1,700 m a.s.l. (Rougier, 2012). 4 5 133 Sahagian (1988) used the distribution of Cenomanian shoreline deposits from the Trans-Sahara 6 7 134 seaway preserved near the Hoggar to estimate that 2–3 km of uplift likely occurred in the area 8 9 135 post-Cenomanian deposition. Volcanic centres, such as Mt. Tahat (2,909 m a.s.l.) in the Atakor 10 11 136 area (Fig. 1), developed locally on top of the broader Hoggar swell during the Cenozoic. 12 13 137 Previous thermochronological analyses in the region have mainly focussed on outcrops 14 15 138 from the Hoggar Massif (Carpena et al., 1988; Meyer, 1990; Cavellec, 2006; Rougier et al., 16 139 2013). Rougier et al. (2013) collected extensive apatite (U-Th)/He data and determined that the 17 18 140 last phase of cooling and exhumation of the Hoggar Massif likely occurred during the Eocene. 19 20 141 Apatite fission-track data from nearby basement outcrops in Aïr (Fig. 1; Cavellec, 2006) yield a 21 22 142 central age of 44 ± 2.6 Ma, and linear cooling from peak temperatures >100°C in the early 23 143 Cenozoic was interpreted based on thermal history modelling. Fission-track data from 24 25 144 Carboniferous-Permian outcrops near Arlit (Fig. 1; Meyer, 1990) also yield similar Eocene- 26 27 145 Oligocene ages (41-28 Ma), but track length data were not available to constrain thermal history 28 29 146 models. Roberts & White (2010) also estimated that uplift of the Hoggar initiated during the 30 31 147 Eocene based on modelling of longitudinal river profiles. 32 33 148 34 35 149 NEW THERMOCHRONOLOGICAL DATA FROM THE ILLIZI BASIN 36 37 150 Data Collection and Methodology 38 39 40 151 Thermal Maturity 41 42 152 Integration of thermal maturity and apatite fission-track data provides constraints on the 43 44 153 maximum paleotemperature of the sedimentary fill, and the timing of the last major cooling 45 46 154 event (e.g., Green & Duddy, 2012 and references therein). Vitrinite and bitumen reflectance and 47 155 Rock-Eval data was collected from a suite of drill cuttings from Well A in the Illizi Basin (Fig. 48 49 156 1) in order to constrain the thermal maturity and peak paleotemperatures of Silurian to 50 51 157 Carboniferous strata in the study area. Reflectance data was measured by two different 52 53 158 laboratories (KK: Keiraville Konsultants and EGS: Egs-ploration). No sample count exceeds 14 54 159 measurements due to limited sample volume, and hence maturity estimates derived from the 55 56 160 reflectance data must be treated with some caution. Only samples with > 5 measurements are 57 58 6 59 60 FOR REVIEW PURPOSES ONLY Page 7 of 41 Basin Research

1 2 3 161 have been included in the study (Table 1). Bitumen reflectance was converted to vitrinite 4 5 162 reflectance equivalent using a relationship from Schoenherr et al. (2007). The vitrinite 6 7 163 reflectance data (and equivalents) were converted to an indicative estimate of maximum paleo- 8 9 164 temperature using Easy%Ro (Sweeney & Burnham, 1990) and a fixed heating rate of 1°C/Myr. 10 11 165 Rock-Eval pyrolysis data (Table 2) were screened according to the criteria of English et al. 12 166 (2015) and Peters & Cassa (1994). The Tmax to vitrinite reflectance conversion was adopted from 13 14 167 Jarvie et al. (2001) and Peters et al. (2005). 15 16 168 Apatite Fission-Track 17 18 19 169 Ten sandstone-bearing intervals in Well A, ranging in age from Carboniferous (Namurian) 20 170 to Ordovician, were also sampled for apatite-fission track analysis. Fission-track analysis was 21 22 171 carried out by Geotrack International according to the sample preparation details described by 23 24 172 Green (1986). Fission-track ages were determined by the external detector method (Gleadow, 25 26 173 1981) with zeta calibration (Hurford & Green, 1983) using dosimeter glass CN5 and a zeta of 27 28 174 392.9 ± 7.4 (analyst MEM – Geotrack International). Inverse modelling of the apatite fission- 29 175 track data was utilised to constrain the range of possible time-temperature histories that are 30 31 176 consistent with the measured data, and in particular to constrain (a) the timing and magnitude of 32 33 177 maximum paleotemperature and (b) the timing and magnitude of the last major cooling event. 34 35 178 Inverse modelling was carried out in HeFTy v.1.8.2 (Ketcham, 2005) using the annealing kinetic 36 179 model of Ketcham et al. (2007). Chlorine content (wt.%) was used as the kinetic parameter, and 37 38 180 due to the generally low Cl contents (< 0.5 wt.%), each sample was modelled as a single 39 40 181 population. C-axis projection was not used. The inverse models were run until 10,000 good paths 41 42 182 were found. An acceptable and a good path were defined as having a goodness-of-fit (GOF) of > 43 183 0.05 and > 0.5 respectively according to the Kolmogorov-Smirnov test. 44 45 46 184 Results 47 48 185 Well A in the Illizi Basin penetrated 2118 m of Paleozoic stratigraphy ranging in age from 49 50 186 Carboniferous (Namurian) to Ordovician. The results of the thermal maturity and apatite fission- 51 52 187 track analysis are displayed in Tables 1-3 and graphically in Figure 2. The complete apatite 53 188 fission-track dataset can be accessed in the Data Repository. The default profiles in Figure 2 54 55 56 57 58 7 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 8 of 41

1 2 3 189 illustrate predicted thermal maturity and apatite fission-track age if no additional burial is 4 5 190 assumed. 6 7 191 Thermal Maturity 8 9 10 192 From the thermal maturity data (Fig. 2a), it is readily apparent that measured peak maturity 11 12 193 values are consistently higher than what would be predicted from the present-day burial depth 13 194 (the deposition of the preserved stratigraphy alone). The slope of the default maturity profile is 14 15 195 broadly similar to the measured peak maturity profile, suggesting that the peak paleogeothermal 16 17 196 gradient is likely similar to the present-day geothermal gradient. These observations confirm that 18 19 197 this sedimentary sequence has been subjected to higher temperatures in the past, likely due to 20 198 deeper burial, and that significant exhumation of the basin has occurred. 21 22 23 199 Apatite Fission-Track 24 25 200 The ten sandstone samples for fission-track analysis were derived from a limited volume of 26 27 201 drill cuttings. Two of the samples yielded no apatite grains and the apatite yield was generally 28 29 202 moderate in the other eight samples (grain counts ranged between 6 and 21). The P(χ2) test was 30 203 applied to all samples, using a probability >5% as indicative of a homogeneous population 31 32 204 (Galbraith, 1981). One sample (GC1085-3) produced a limited amount of data which failed the 33 34 205 P(χ2) test, and is therefore excluded from further analysis here. Minor filtering in four of the 35 36 206 remaining seven samples removed occasional spurious apatite grains with outlier chlorine 37 207 contents or outlier fission track ages that appear to represent contamination. A summary of the 38 39 208 final filtered dataset is presented in Table 3, but the data from the excluded grains from samples 40 41 209 GC1085-2, GC1085-6, GC1085-7 and GC1085-8 are also provided in the Data Repository for 42 43 210 completeness. The presented fission-track ages are pooled ages commonly used when P(χ2) > 44 45 211 5% (Galbraith & Laslett, 1993). The two samples with P(χ2) < 5% have central ages of 29.7±5.9 46 212 Ma (GC1085-7) and 8.5±2.4 Ma (GC1085-10). Only GC1085-1 (Namurian) provided sufficient 47 48 213 track length measurements (>100) to define a statistically meaningful track length distribution. 49 50 214 The measured apatite fission-track ages (Fig. 2b) for all samples, including the 51 52 215 Carboniferous (Namurian) sample from a depth of only 180 m, are younger than their 53 54 216 corresponding depositional ages, indicating that fission-track annealing has affected the entire 55 56 217 preserved stratigraphic sequence, with increased annealing in deeper samples that have been 57 58 8 59 60 FOR REVIEW PURPOSES ONLY Page 9 of 41 Basin Research

1 2 3 218 exposed to higher temperatures. The default profile illustrates the modelled vertical profile of 4 5 219 apatite fission-track age assuming no additional burial beyond that preserved today. As chlorine 6 7 220 content has been demonstrated to exert a systematic influence on annealing rates (Gleadow & 8 9 221 Duddy, 1981; Green et al., 1985, 1986), a fixed chlorine content of 0.1 wt.% has been assumed 10 11 222 for the purposes of generating a vertical profile. Of the 93 apatite grains included in the analysis, 12 223 80% have chlorine contents less than or equal to 0.1 wt.%, and the average chlorine content is 13 14 224 0.07 wt.%. The default profile shows a characteristic “break-in-slope” (Fitzgerald & Gleadow, 15 16 225 1988, 1990; Fitzgerald et al., 1995; Green & Duddy, 2012) between present-day temperatures of 17 18 226 ~60 and 90°C, while total annealing is expected below ~110 °C. The measured fission-track ages 19 227 are routinely younger than the default profile, indicating this stratigraphic sequence has 20 21 228 experienced hotter temperatures in the past. Samples from below ~1,000 m depth (Devonian, 22 23 229 Silurian and Ordovician) are interpreted to have been totally annealed in the past (maximum 24 25 230 temperatures > 110°C). Sixty-six apatite grains were analysed in these deeper samples (GC1085- 26 231 6, GC1085-7, GC1085-8, GC1085-9, GC1085-10) yielding fission-track ages ranging from 73-0 27 28 232 Ma with an average of 17 Ma (see Data Repository); 96% of these grains yielded Eocene and 29 30 233 younger fission-track ages. The shallower Carboniferous samples have only been partially 31 32 234 annealed, and the fission-track age bears no relation to any specific thermal event. 33 34 235 Inverse Modelling of the Fission-Track Data 35 36 236 Inverse modelling was carried out in HeFTy to constrain the range of possible time- 37 38 237 temperature histories that are consistent with the measured fission-track data (Ketcham, 2005). 39 40 238 The initial (deposition) and final (present-day) conditions were defined in the model set-up, and 41 42 239 additional constraint boxes were placed in temperature-time (T-t) space such that the inverse 43 240 models would honour our general understanding of the burial history of the basin – i.e., pre- 44 45 241 Hercynian burial, Hercynian exhumation, and post-Hercynian burial. Hercynian exhumation is 46 47 242 modelled to be consistent with the maximum preserved thicknesses of Carboniferous strata in the 48 49 243 eastern Illizi Basin (Galeazzi et al., 2010) and the Hercynian subcrop patterns observed 50 51 244 immediately to the north of the study area (English et al., 2016). Straight-line segments were 52 245 modelled between the constraint boxes such that the inverse modelling would identify a series of 53 54 246 relatively simple thermal histories that honour the fission-track data. The primary objective of 55 56 247 the inverse modelling was to identify what constraints can be placed on the timing and 57 58 9 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 10 of 41

1 2 3 248 magnitude of maximum paleotemperature and also the timing and magnitude of the last major 4 5 249 cooling event. Sample GC1085-1 (Namurian) was selected for inverse modelling as this sample 6 7 250 passed the P(χ2) test (11.7%) and provided the highest number of track length measurements (n 8 9 251 = 106). As the number of measured track lengths is more limited in the deeper samples (Table 3), 10 11 252 it was elected to combine the Devonian and Silurian samples GC1085-6, GC1085-7 and 12 253 GC1085-8 to provide a more statistically meaningful sample set (n = 41) for inverse modelling. 13 14 254 These samples were selected because they are from a narrow depth range (1385-1560 m), are at 15 16 255 the lower temperature end of samples that have been fully annealed in the past (76-82°C present- 17 18 256 day), and the combined fission-track age dataset also passes the P(χ2) test (5.2%). 19 20 257 Namurian Sample GC1085-1 21 22 258 The inverse modelling results for sample GC1085-1 (Namurian) are presented in Figure 3a. 23 24 259 The assumed timing constraints for the inverse modelling of this sample are as follows: 25 26 260 • A pre-deposition constraint (400-325 Ma) to account for inherited grains. 27 28 29 261 • The depositional constraint was set to approximate Namurian age (325-315 Ma) at 15- 30 262 25°C surface temperature. 31 32 33 263 • The post-deposition constraints were defined on the basis of preserved stratigraphy and 34 35 264 regional stratigraphic observations, and assume pre-Hercynian burial (300-260 Ma), 36 265 Hercynian exhumation (260-160 Ma), and post-Hercynian reburial (180-0 Ma). 37 38 39 266 • Finally, the present-day temperature, based on downhole gauge temperature data from 40 41 267 the well, defined the terminal conditions of the model. 42 43 268 The model was run until 10,000 good paths were identified. The vertices of the good paths 44 45 269 (GOF > 0.5) are highlighted in purple, while the vertices of the acceptable paths (GOF > 0.05) 46 270 are highlighted in green. The cloud of good path vertices during post-Hercynian reburial 47 48 271 indicates that the maximum paleotemperature of the Namurian sample is likely to be in the 60- 49 50 272 80°C range. Higher peak temperatures are allowable if maximum burial occurred during the Late 51 52 273 Jurassic or Cretaceous as opposed to the Cenozoic (Fig. 3a). Hence, inverse modelling of the 53 274 Namurian sample confirms that these strata reached maximum temperatures ~30-50°C higher 54 55 275 than present-day, but does not provide clear constraints on the timing of maximum burial. The 56 57 58 10 59 60 FOR REVIEW PURPOSES ONLY Page 11 of 41 Basin Research

1 2 3 276 best-fit of all the inverse model solutions is highlighted by the black line in the thermal history 4 5 277 plot and reflects cooling from maximum temperatures in the Eocene (Fig. 3a). This inverse 6 7 278 model solution provides a goodness-of-fit of 0.98 and 0.97 for the fission-track age and track 8 9 279 length distribution respectively. This solution is non-unique and simply represents the best-fit of 10 11 280 10,000 different thermal histories that can provide a good fit to the measured data. 12 13 281 Silurian-Devonian Combined Sample GC1085-6,-7,-8 14 15 282 The inverse modelling results for the deeper combined samples GC1085-6, GC1085-7 and 16 17 283 GC1805-8 (Devonian-Silurian) are presented in Figure 3b. The assumed timing constraints for 18 19 284 the inverse modelling of this sample are as follows: 20 21 285 • A depositional constraint (423-400 Ma) at 5-15°C surface temperature. A pre- 22 23 286 depositional constraint to allow for inherited grains is not required here as these samples 24 25 287 have been fully annealed during burial. 26 27 288 • The post-deposition constraints were defined on the basis of preserved stratigraphy and 28 29 289 regional stratigraphic observations, and assume pre-Hercynian burial (300-260 Ma), 30 290 Hercynian exhumation (260-160 Ma), and post-Hercynian reburial (180-0 Ma). 31 32 33 291 • The present-day temperature defined the terminal conditions of the model. 34 35 292 • In addition, two cooling constraint boxes were added from 140-0 Ma at temperature 36 37 293 intervals of 90-100°C and 70-85°C. These boxes are intermediate steps between post- 38 39 294 Hercynian reburial and present-day conditions, but serve to capture the constraints that 40 41 295 the fission-track data can place on the timing of cooling into the partial annealing zone 42 296 during the latest phase of exhumation. 43 44 45 297 The model was again run until 10,000 good paths were identified. The cloud of purple 46 298 good-path vertices (Fig. 3b) during post-Hercynian reburial confirms that the apatite fission-track 47 48 299 data cannot provide any constraints on the thermal history above 110°C (due to total annealing), 49 50 300 except confirming that cooling from maximum temperatures had to initiate before ~30 Ma. The 51 52 301 cloud of good path vertices in the 90-100°C constraint box indicates that cooling through this 53 302 temperature range likely occurred no earlier than ~50 Ma and no later than ~10 Ma – most likely 54 55 303 during the 35-20 Ma window. Finally, the cloud of good path vertices in the 70-85°C constraint 56 57 58 11 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 12 of 41

1 2 3 304 box indicates that these samples reached temperatures close to present-day no earlier than ~30 4 5 305 Ma. Hence, inverse modelling of the Devonian-Silurian combined sample confirms that these 6 7 306 strata reached higher temperatures in the total annealing zone in the past, and cooled by > 20°C 8 9 307 during the Eocene or later to reach their present-day temperatures. The best-fit of all the inverse 10 11 308 model solutions is highlighted by the black line in the thermal history plot and reflects cooling 12 309 from maximum paleotemperatures in the Eocene (Fig. 3b). This inverse model solution provides 13 14 310 a goodness-of-fit of 0.98 and 0.99 for the fission-track age and track length distribution 15 16 311 respectively. This solution is non-unique and simply represents the best-fit of 10,000 different 17 18 312 thermal histories that can provide a good fit to the measured data. 19 20 313 Summary 21 22 314 The inverse modelling confirms that deeper burial and hotter temperatures occurred in the 23 24 315 study area in the past. The inverse modelling of the Namurian samples indicates maximum 25 26 316 paleotemperatures ~30-50°C higher than present-day at some point during the Late Jurassic to 27 28 317 Cenozoic (Fig. 3a). The inverse modelling of the deeper Devonian-Silurian samples indicates 29 318 that at least 20°C of cooling occurred during the Eocene or later (Fig. 3b). Two main candidate 30 31 319 tectonic events could have led to cooling from maximum burial temperature in this region 32 33 320 (Galeazzi et al., 2010). Model 1 is that exhumation from maximum burial conditions occurred 34 35 321 during the Cenozoic and is related to uplift of the Hoggar Massif to the south of the study area. 36 322 Model 2 is that exhumation from maximum burial conditions occurred during the Middle 37 38 323 Cretaceous and is related to possible uplift associated with the Austrian tectonic event. Model 2 39 40 324 would still require some Cenozoic cooling to honour the fission-track data from the deeper 41 42 325 samples (Fig. 3b). 43 44 326 45 46 327 1D BURIAL HISTORY MODELLING 47 48 49 328 1D burial and thermal history modelling for Well A was carried out using the Genesis 50 329 software (developed by Zetaware). Inputs for the thicknesses and lithologies of preserved and 51 52 330 missing/eroded stratigraphy, present-day temperatures, and thermal maturity were based on well 53 54 331 data and regional stratigraphic analysis (English et al., 2016). The youngest preserved 55 56 332 stratigraphy in Well A is Carboniferous, and missing/eroded stratigraphy assumptions were 57 58 12 59 60 FOR REVIEW PURPOSES ONLY Page 13 of 41 Basin Research

1 2 3 333 reconstructed from younger preserved strata documented elsewhere in the Illizi and Berkine 4 5 334 basins (Turner et al., 2001; Yahi et al., 2001; Makhous & Galushkin, 2003; Turner & Sherif, 6 7 335 2007; Underdown et al., 2007; Dixon et al., 2010, Galeazzi et al., 2010) and in outcrops 8 9 336 (Swezey, 2009). Paleobathymetry was based on well-derived depositional facies and data from 10 11 337 Yahi et al. (2001) from the Berkine Basin. The onset of post-Hercynian deposition in the study 12 338 area is interpreted to have occurred in the Early Jurassic based on observed depositional edges 13 14 339 within the Illizi Basin (Fig. 1). Paleolatitudes were used to approximate the paleo-surface 15 16 340 temperature (Wygrala, 1989; Underdown, 2006). 17 18 341 Measured temperatures in Well A and 10 nearby wells indicate an average present-day 19 20 342 geothermal gradient of 38°C/km (range 36-41°C/km), assuming an annual surface temperature 21 22 343 of 22°C. The peak paleogeothermal gradient in the area is estimated to be ~37°C/km based on 23 24 344 available thermal maturity data (English et al., 2016). The calculated present-day basal heat flow 25 2 26 345 is 65 mW/m , which is consistent with documented heat flows in the southern Illizi Basin (60 - 27 346 100 mW/m2; Lesquer et al., 1990). The basal heat flow was held constant through time in the 28 29 347 Genesis models due to: (a) the similarity between the present-day geothermal gradient 30 31 348 (38°C/km) and peak paleogeothermal gradients during maximum burial (~37°C/km), and (b) the 32 33 349 absence of any major rifting event in the vicinity. Variations in heat flow have been assumed in 34 35 350 some other studies in North Africa, such as in the Ahnet and Reggane basins (Fig. 1), where peak 36 351 temperatures are related to a brief ‘heat spike’ or thermal anomaly at ~200 Ma, characterized by 37 38 352 high peak paleogeothermal gradients (~60-80°C/km; Logan & Duddy, 1998) that are not 39 40 353 observed in our Illizi Basin dataset. 41 42 354 Two independent 1D burial and thermal history models for Well A were constructed (Fig. 43 44 355 4) – one with maximum burial during the Cenozoic (Model 1) and one with maximum burial 45 46 356 during the Middle Cretaceous (Model 2). Both thermal history models honour the preserved 47 357 stratigraphy at Well A and the present-day temperature data. The post-Namurian depositional 48 49 358 and erosional history was adjusted to calibrate to the available thermal maturity and apatite 50 51 359 fission-track age data (Fig. 2). The modelled temperature-time (T-t) pathways for each layer in 52 53 360 Genesis were imported into HeFTy, and a fixed chlorine content of 0.1 wt.% has been assumed 54 55 361 for the purposes of generating a vertical profile of fission-track age for both Model 1 and Model 56 362 2 (Fig. 2b). These two vertical profiles are practically indistinguishable from each other, predict 57 58 13 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 14 of 41

1 2 3 363 a “break-in-slope” at much shallower depths than the default profile, and are more consistent 4 5 364 with the measured fission-track age data. There is a small discrepancy in the shallower samples 6 7 365 between the measured fission-track ages and the continuous profiles, and this may be because of 8 9 366 (1) inherited tracks within these partially annealed grains or (2) a slightly higher Cl content. For 10 11 367 example, the analysed grains in the shallowest Namurian sample have an average Cl content of 12 368 0.16 wt.%, and the modelled fission-track age for the actual grain population (blue squares – 13 14 369 Model 1; red squares – Model 2) plots closer to the measured fission-track age (red circle) than 15 16 370 the continuous profile assuming 0.1 wt.% Cl. Finally, both Model 1 and Model 2 were calibrated 17 18 371 to the fission-track age and track length distributions for Namurian sample (GC1085-1) and the 19 372 combined Devonian-Silurian samples (GC1085-6, GC1085-7 and GC1085-8) via forward 20 21 373 modelling of the associated T-t pathway in HeFTy. The forward modelling results for Model 1 22 23 374 and Model 2 are displayed in Figures 5 and 6 respectively. The goodness-of-fit (GOF) is greater 24 25 375 than 0.85 in all cases except for the fission-track age in the Namurian sample where pre- 26 376 depositional inheritance may be the cause of some additional variation. 27 28 29 377 Model 1 assumes additional post-Hercynian sedimentary burial throughout the Mesozoic 30 31 378 with maximum burial in the Early Eocene (52 Ma), followed by (~1 km) exhumation during the 32 379 Eocene-Miocene (Fig. 4a). Minor mid-Aptian exhumation (~25 m) is also included in this model 33 34 380 to represent the Austrian unconformity. Model 2 assumes that maximum temperature occurs 35 36 381 during the Aptian (124 Ma) followed by ~570 m of Austrian exhumation, with renewed Late 37 38 382 Cretaceous and early Cenozoic burial, and ~840 m exhumation initiating during the Eocene (Fig. 39 383 4b). Both Model 1 and Model 2 honour the apatite fission-track and thermal maturity data for 40 41 384 Well A (Figs. 2, 5 and 6). 42 43 385 44 45 46 386 TIMING OF MAXIMUM BURIAL IN THE ILLIZI BASIN 47 48 387 In the Illizi Basin, deformation and erosion associated with the Austrian tectonic event has 49 50 388 been focussed along the north–south Amguid-El Biod fault trend at the western margin of the 51 52 389 basin (Galeazzi et al., 2010), while the more central parts of the Illizi Basin show less effect. 53 390 Similarly, the Tihemboka Arch that defines the eastern boundary of the Illizi Basin does not 54 55 391 show evidence of Austrian unroofing (Boote et al., 2012). Within the study area, it is difficult to 56 57 58 14 59 60 FOR REVIEW PURPOSES ONLY Page 15 of 41 Basin Research

1 2 3 392 comment with certainty on the magnitude of the Austrian erosional event due to the lack of 4 5 393 sedimentary record. However, ~80 km north-northwest of Well A, pre- and post-Austrian strata 6 7 394 at the Tin Fouyé Tabankort field (Chiarelli et al., 1978; Fig. 1) do not display any significant 8 9 395 angular discordance and are uniformly tilted northward together by a younger event. Based on 10 11 396 this evidence, the preferred model for the study area involves maximum burial during the 12 397 Cenozoic followed by exhumation and cooling in the Eocene-Miocene (Model 1). While the 13 14 398 Mesozoic portion of the modelled thermal history solution is non-unique (i.e., Model 2 is also a 15 16 399 possible valid model), the new dataset does require significant (0.5-1.0 km) Cenozoic 17 18 400 exhumation in the study area to match the uniformly young fission-track ages in the deeper 19 401 samples (e.g., Fig. 3b). The timing of the end of the exhumation cannot be definitively resolved, 20 21 402 but a good fit to the fission-track data was achieved with significant exhumation ending during 22 23 403 the Miocene. In the preferred Model 1, the total amount of Cenozoic exhumation at Well A in 24 25 404 the Illizi Basin is estimated at ~1.0–1.1 km. 26 27 405 28 29 406 GEOMETRY AND MAGNITUDE OF HOGGAR UPLIFT AND EXHUMATION 30 31 32 407 Comparison with Regional Thermochronological Data 33 34 408 Previous apatite fission-track data over the Hoggar have provided widespread Mesozoic 35 36 409 ages (Carpena et al., 1988). New apatite fission-track data presented in this study from the Illizi 37 410 Basin support other recent apatite (U-Th)/He thermochronologic data (Rougier et al., 2013) and 38 39 411 inverse modelling of longitudinal river profiles (Roberts & White, 2010), which indicate that the 40 41 412 last major exhumation phase initiated during the Eocene. Rougier et al. (2013) reported apatite 42 43 413 (U-Th)/He data from exposed basement samples adjacent to the Lower Cretaceous Serouenout 44 45 414 deposits (Fig. 1), and interpreted that these rocks underwent post-depositional heating to 60- 46 415 80°C, corresponding to 1-3 km of additional burial (assuming an Eocene geothermal gradient of 47 48 416 22-28°C/km and surface temperatures of 15-30°C), prior to exhumation. Using the maximum 49 50 417 burial conditions assumed at Well A in the Illizi Basin (i.e., Eocene geothermal gradient of 36- 51 52 418 41°C/km and surface temperature of 24°C), exhumation in the Serouenout area would 53 419 correspond to ~0.9-1.6 km. It is possible that previously published Mesozoic apatite fission-track 54 55 420 ages from outcrop samples of the Hoggar Massif (Carpena et al., 1988) were only partially 56 57 58 15 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 16 of 41

1 2 3 421 annealed during subsequent Mesozoic-Cenozoic reburial, and hence the fission-track ages may 4 5 422 not directly relate to any specific thermal event. 6 7 423 South of the Hoggar, in the Arlit area of Niger (Fig. 1), vitrinite reflectance and Rock-Eval 8 9 424 pyrolysis data from the Carboniferous (Visean) Guézouman/Tarada Formation in the Tim Mersoï 10 11 425 Basin indicate a thermal maturity of 0.66 Ro% and a Tmax of 434°C at ~100m depth (sample 12 13 426 927/607; Forbes et al., 1988). These measurements correspond to an estimated peak temperature 14 15 427 of ~109°C using Easy%Ro (Sweeney & Burnham, 1990) and a fixed heating rate of 1°C/Myr. 16 428 Rock-Eval pyrolysis data from the same formation in the Akouta area (sample CMK5; Salze, 17 18 429 1998), screened according to the criteria of English et al. (2015), yield a Tmax of 430°C, and an 19 20 430 equivalent Ro% of ~0.56 corresponds to an estimated peak temperature of ~95°C. Using the 21 22 431 maximum burial conditions from Well A, these data suggest that the Visean formations reached 23 432 maximum burial depths of ~1.7-2.3 km in the Tim Mersoï Basin. Apatite fission-track data from 24 25 433 nearby basement outcrops in Aïr (Cavellec, 2006; Fig. 1) yield a central age of 44 ± 2.6 Ma and 26 27 434 an average track length 12.56 ± 0.22 µm. Based on thermal history modelling, Cavellec (2006) 28 29 435 interpreted a best-fit model with linear cooling from peak temperatures >100°C in the early 30 31 436 Cenozoic. Fission-track data from Carboniferous-Permian outcrops near Arlit (Meyer, 1990) also 32 437 yield similar Eocene-Oligocene ages (41-28 Ma), but track length data were not available to 33 34 438 constrain thermal history models. Regionally, distinct Cenozoic exhumation has been interpreted 35 36 439 in fission-track studies across the Ahnet Basin (Logan & Duddy, 1998), Tihemboka Arch 37 38 440 (Glover, 1999; Boote et al., 2012), and Al Qarqaf Arch (Underdown et al., 2007), with only 39 441 modest Cenozoic exhumation interpreted further north in the Berkine-Ghadames Basin 40 41 442 (Underdown et al., 2007) (Fig. 1). 42 43 443 In summary, these regional data confirm that a major Cenozoic cooling and exhumation 44 45 444 event extended across the Hoggar region and into the surrounding sedimentary basins to the 46 47 445 north and south. The preservation of a relatively complete Mesozoic-Cenozoic stratigraphic 48 49 446 sequence in both the Berkine Basin (Galeazzi et al., 2010) and the southern Iullemmeden Basin 50 51 447 (Zanguina et al., 1998) constrains the lateral extent of this exhumation event to the north and 52 448 south respectively. 53 54 55 449 Geometry of the Hoggar Uplift 56 57 58 16 59 60 FOR REVIEW PURPOSES ONLY Page 17 of 41 Basin Research

1 2 3 450 A regional schematic structural section has been constructed from the Berkine Basin in the 4 5 451 north, across the Hoggar Massif, to the Iullemmeden Basin to the south, to define the geometry 6 7 452 of the Hoggar uplift (Fig. 7). Following Rougier et al. (2013), we interpret that at least parts of 8 9 453 the Hoggar Massif endured significant post-Hercynian Mesozoic and early Cenozoic reburial, 10 11 454 although it remains unknown if this reburial affected the entire Hoggar region. Cenozoic rock 12 455 uplift occurred across the Hoggar swell and surrounding basins over a distance >1,500 km from 13 14 456 north to south, and uplift magnitudes within the core of the swell are in excess of 2 km (Fig. 7). 15 16 457 These uplift estimates are consistent with ~1 km post-depositional burial of the Serouenout 17 18 458 sandstones (at lower elevations), followed by uplift to their present-day elevations. Uplift 19 459 magnitudes may be even greater in some local areas of the Hoggar such as Atakor (off-section 20 21 460 from Fig. 7) where the Precambrian basement reaches elevations of ~2,400 m a.s.l. (Girod, 22 23 461 1971). Within the adjoining sedimentary basins, the magnitude of exhumation is interpreted to 24 25 462 increase from the flanks towards the central part of the Hoggar uplift. The reduction in erosion 26 463 within the core of the Hoggar (Fig. 7) may be due to the presence of more resistant crystalline 27 28 464 basement compared to the sedimentary strata, or due to a reduction in fluvial erosion rates due to 29 30 465 a smaller drainage area and lower discharge rates. 31 32 466 Driving Mechanisms for Uplift 33 34 35 467 The driving mechanisms for uplift of the Hoggar swell have been the subject of much 36 468 debate (Liégeois et al., 2005). A deep-mantle plume origin has been previously discounted based 37 38 469 on the lack of an associated present-day thermal anomaly (Lesquer et al., 1988; 1989), and the 39 40 470 absence of expected evidence along the plate’s projected path since 35 Ma (Liégeois et al., 41 42 471 2005). As an alternative, Liégeois et al. (2005) proposed that edge-driven convection (King & 43 472 Anderson, 1998), associated with changes in lithospheric thickness beneath the shield, may have 44 45 473 facilitated asthenospheric mantle uprising and decompression melting during Eocene-Recent 46 47 474 reactivation of Pan-African basement structures, linked to Africa-Eurasia collision to the north. 48 49 475 Moucha & Forte (2011) and Jones et al. (2012) have both interpreted dynamic support for the 50 51 476 Hoggar swell, indicating a role for underlying mantle convection. The data presented here 52 477 indicates that the initiation of Cenozoic exhumation in the Illizi Basin, on the northern flank of 53 54 478 the Hoggar swell, is coincident with the onset of intra-plate volcanism across a number of other 55 56 479 North African magmatic provinces, including the Tibesti and Darfur districts (Wilson & 57 58 17 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 18 of 41

1 2 3 480 Guiraud, 1992; Wilson et al., 1998; Liégeois et al., 2005; Fig. 1), and is broadly co-eval with the 4 5 481 onset of Africa-Eurasia collision during the Mid-Late Eocene (e.g. Frizon de Lamotte et al., 6 7 482 2011). This collisional event resulted in inversion along the northwestern Atlas zone (Fig. 1), and 8 9 483 concomitant minor angular unconformities can be observed in many North African sedimentary 10 11 484 basins (e.g. Berkine, Oued Mya and Iullemmeden basins; Guiraud et al., 2005; Lang et al., 12 485 1990). However, the relationship between the Atlas event and the Hoggar uplift still remains 13 14 486 unclear. Deposition of Upper Eocene-Pliocene sediments (the “Continental Terminal”) across 15 16 487 Saharan Africa (Kilian, 1931) may represent the onset of clastic sedimentation derived from the 17 18 488 growing intracratonic swells, and the uplifting Atlasic belt to the north. Additionally, based on 19 489 detrital zircon age-dating, the Hoggar region has been proposed as one of the possible source 20 21 490 regions of reworked Oligocene to Miocene clastics of the Numidian Flysch deposited in the 22 23 491 western Mediterranean (Thomas et al., 2010). 24 25 492 26 27 28 493 CONCLUSIONS 29 30 494 This study quantifies the magnitude and timing of kilometre-scale uplift and exhumation of 31 32 495 the Illizi Basin on the northern margin of the Hoggar swell. Integration with regional data 33 496 indicates that the Cenozoic uplift event in the Hoggar region extended over a distance in excess 34 35 497 of 1,500 km from north to south into the flanking basins, and the magnitude of rock uplift in the 36 37 498 core of the swell is estimated to be in excess of 2 km. The timing of Cenozoic uplift is broadly 38 39 499 coincident with magmatism on the Hoggar and other North African magmatic provinces, and 40 500 with the onset of tectonic compression in the Atlasic belt to the north. Thermal history studies in 41 42 501 sedimentary basins flanking other North African Cenozoic highs would help to constrain the true 43 44 502 geometry and timing of these enigmatic rock uplifts, and help to unravel the continental-scale 45 46 503 lithospheric and sub-lithospheric processes behind their genesis. 47 48 504 49 50 51 52 53 54 55 56 57 58 18 59 60 FOR REVIEW PURPOSES ONLY Page 19 of 41 Basin Research

1 2 3 505 ACKNOWLEDGMENTS 4 5 6 506 We thank Petroceltic International, Sonatrach and Enel, for sponsoring this study and granting 7 507 permission for publication. Additionally, we gratefully acknowledge Zhiyong He and Rich 8 9 508 Ketcham for the generous donations of the Genesis and HeFTy software for this research. This 10 11 509 manuscript has also benefitted from input by Dermot Corcoran, Sean McDade, Ian Duddy, 12 13 510 Lorraine Eglinton and Sabine Cavellec in particular, and from constructive feedback from Cindy 14 15 511 Ebinger, Yves Missenard and two anonymous reviewers. We also gratefully acknowledge 16 512 Richard Dixon and Jake Hossack for sharing some of their insights on the evolution of the 17 18 513 Hoggar swell. 19 20 514 21 22 23 515 CONFLICT OF INTEREST 24 25 516 No conflict of interest declared. 26 27 517 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 19 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 20 of 41

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1 2 3 571 CAVELLEC, S. (2006) Evolution diagénétique du basin de Tim Mersoï et conséquences pour la 4 5 572 génèse des minéralisations uranifères dans les formations carbonifères du Guezouman et du 6 7 573 Tarat (district Arlit-Akokan, Niger). PhD thesis, Université du Paris-Sud, Paris, France. 8 9 574 CHOUBERT, A. & FAURE-MURET, A. (1990) International geological map of Africa. CGMW 10 11 575 (Commission of the Geological Map of the World), UNESCO, Paris, France, scale 1:5,000,000, 12 13 576 6 sheets. 14 15 577 DAUTRIA, J.M. & LESQUER, A. (1989) An example of the relationship between rift and dome: 16 17 578 recent geodynamic evolution of the Hoggar Swell and of its nearby regions (Central Sahara, 18 19 579 Southern Algeria and Eastern Niger). Tectonophysics, 163, 45–61. 20 21 580 DIXON, R.J., MOORE, J.K.S., BOURNE, M., DUNN, E., HAIG, D.B, HOSSACK, J., ROBERTS, N., 22 23 581 PARSONS, T. & SIMMONS, C.J. (2010) Integrated petroleum systems and play fairway analysis in 24 582 a complex Palaeozoic basin: Ghadames-Illizi Basin, North Africa. In: Petroleum geology: From 25 26 583 mature basins to new frontiers (Ed. by B.A. Vining & S.C. Pickering), Geol. Soc. Lond., Petrol. 27 28 584 Geol. Conf. Series, 7, 735–760. 29 30 585 ENGLAND, P. & MOLNAR, P. (1990) Surface uplift, uplift of rocks, and exhumation of rocks. 31 32 586 Geology, 18, 1173–1177. 33 34 587 ENGLISH, J.M., LUNN, G.A., FERREIRA, L. & YACU, G. (2015) Geologic evolution of the Iraqi 35 36 588 Zagros, and its influence on the distribution of hydrocarbons in the Kurdistan region. AAPG 37 38 589 Bull., 99, 231–272. 39 40 590 ENGLISH, K.L., REDFERN, J., CORCORAN, D.V., ENGLISH, J.M. & YAHIA CHERIF, R. (2016) 41 42 591 Constraining burial history and petroleum charge in exhumed basins: new insights from the Illizi 43 44 592 Basin, Algeria. AAPG Bull., 100, XXX–XXX. 45 46 593 FABRE, J. (1976) Introduction à la géologie du Sahara algérien et des régions voisines. Sociétié 47 48 594 Nationale d'Édition et de Diffusion, Algiers, Algeria, 422 pp. 49 50 595 FITZGERALD, P.G. & GLEADOW, A.J.W. (1988) Fission-track geochronology, tectonics and 51 52 596 structure of the Transantarctic Mountains in Northern Victoria Land, Antarctica. Chem. Geol., 53 54 597 73, 169–198. 55 56 57 58 22 59 60 FOR REVIEW PURPOSES ONLY Page 23 of 41 Basin Research

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1 2 3 652 KETCHAM, R.A. (2005) Forward and inverse modeling of low-temperature thermochronometry 4 5 653 data. Rev. Min. & Geochem., 58, 275–314. 6 7 654 KETCHAM, R.A., CARTER, A., DONELICK, R.A., BARBARAND, J. & HURFORD, A.J. (2007) 8 9 655 Improved modelling of fission-track annealing in apatite. Am. Mineralogist, 92, 799–810. 10 11 12 656 KILIAN, C. (1931) Des principaux complexes continentaux du Sahara. Comptes Rendus 13 657 sommaire de la Societé Géologique de la France, 9, 109–111. 14 15 16 658 KING, S.D. & ANDERSON, D.L. (1998) Edge-driven convection. Earth Planet. Sci. Lett., 160, 17 659 289–296. 18 19 20 660 KOGBE, C.A. (1981) Cretaceous and Tertiary of the Iullemmeden Basin in Nigeria (West Africa). 21 661 Cret. Res., 2, 129-186. 22 23 24 662 LANG, J., KOGBE, C., ALIDOU, S., ALZOUMA, K.A., BELLION, G., DUBOIS, D., DURAND, A., 25 GUIRAUD, R., HOUESSOU, A., DE KLASZ, I., ROMANN, E., SALARD-CHEBOLDAEFF, M. & 26 663 27 664 TRICHET, J. (1990) The continental terminal in West Africa. J. Afr. Earth Sci., 10, 79–99. 28 29 30 665 LEFRANC, J.P. & GUIRAUD, R. (1990) The continental intercalaire of northwestern Sahara and its 31 666 equivalents in the neighbouring regions. J. Afr. Earth Sci., 10, 27–77. 32 33 34 667 LESQUER, A., BOURMATTE, A. & DAUTRIA, J.M. (1988) Deep structure of the Hoggar domal 35 668 uplift (central Sahara, south Algeria) from gravity, thermal and petrological data. 36 37 669 Tectonophysics, 152, 71–87. 38 39 670 LESQUER, A., BOURMATTE, A., LY, S. & DAUTRIA, J.M. (1989) First heat flow determination 40 41 671 from the Central Sahara: Relationship with the Pan-African belt and Hoggar domal uplift. J. Afr. 42 43 672 Earth Sci., 9, 41–49. 44 45 673 LESQUER, A., TAKHERIST, D., DAUTRIA, J.M. & HADIOUCHE, O. (1990) Geophysical and 46 47 674 petrological evidence for the presence of an “anomalous” upper mantle beneath the Sahara 48 49 675 basins (Algeria). Earth Planet. Sci. Lett., 96, 407–418. 50 51 676 LIÉGEOIS, J.P., BENHALLOU, A., AZZOUNI-SEKKAL, A., YAHIAOUNI, R. & BONIN, B. (2005) The 52 53 677 Hoggar swell and volcanism: Reactivation of the Precambrian Tuareg shield during Alpine 54 55 678 convergence and West African Cenozoic volcanism. In: Plates, plumes and paradigms (Ed. by 56 57 58 25 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 26 of 41

1 2 3 679 G.R. Foulger, J.H. Natland, D.C. Presnall & D.L. Anderson), Geol. Soc. Am. Spec. Paper, 388, 4 5 680 379–400. 6 7 681 LOGAN, P. & DUDDY, I. (1998) An investigation of the thermal history of the Ahnet and Reggane 8 9 682 basins, central Algeria, and the consequences for hydrocarbon generation and accumulation. In: 10 11 683 Petroleum geology of North Africa (Ed. by D.S. MacGregor, R.T.J. Moody & D.D. Clark- 12 13 684 Lowes), Geol. Soc. Lond., Spec. Publ., 132, 131–155. 14 15 685 MAKHOUS, M. & GALUSHKIN, Y.I. (2003) Burial history and thermal evolution of the northern 16 17 686 and eastern Saharan basins. AAPG Bull., 87, 1623-1651. 18 19 687 MEYER, A.J. (1990) Les traces de fission dans l’apatite : Etude expérimentale et application à 20 21 688 l’histoire thermique de bassins sédimentaires. PhD thesis, Institut National Polytechnique de 22 23 689 Lorraine, Nancy, France. 24 25 690 MOUCHA, R. & FORTE, A.M. (2011) Changes in African topography driven by mantle 26 27 691 convection. Nature Geosci., 4, 707–712. 28 29 692 PETERS, K.E. & CASSA, M.R. (1994) Applied source rock geochemistry. In: The petroleum 30 31 693 system – From source to trap (Ed. by L.B. Magoon & W.G. Dow), AAPG Memoir, 60, 93–120. 32 33 694 PETERS, K.E., WALTERS, C.C. & MOLDOWAN, J.M. (2005) The Biomarker Guide, Volume 1: 34 35 695 Biomarkers and Isotopes in the Environment and Human History. Cambridge University Press, 36 37 696 Cambridge, UK, 492 pp. 38 39 697 PHILIPPE, M., CUNY, G., BAMFORD, M., JAILLARD, E., BARALE, G., GOMEZ, B., OUAJA, M., 40 41 698 THÉVENARD, F., THIÉBAUT, M. & VON SENGBUSCH, P. (2003) The palaeoxylological record of 42 43 699 Metapodocarpoxylon libanoticum (Edwards) Dupéron-Laudoueneix et Pons and the Gondwana 44 700 Late Jurassic–Early Cretaceous continental biogeography. J. Biogeog., 30, 389–400. 45 46 47 701 ROBERTS, G.G. & WHITE, N. (2010) Estimating uplift rate histories from river profiles using 48 702 African examples. J. Geophys. Res., 115, B02406. 49 50 51 703 ROUGIER, S. (2012) Interactions lithosphere-asthenosphere et mouvements verticaux: Le cas du 52 704 Massif du Hoggar. PhD thesis, Universite Paris-Sud, Paris, France. 53 54 55 56 57 58 26 59 60 FOR REVIEW PURPOSES ONLY Page 27 of 41 Basin Research

1 2 3 705 ROUGIER, S., MISSENARD, Y., GAUTHERON, C., BARBARAND, J., ZEYEN, H., PINNA, R., 4 5 706 LIÉGEOIS, J.P., BONIN, B., OUABADI, A., EL-MESSAOUD DERDER, M. & FRIZON DE LAMOTTE, D. 6 7 707 (2013) Eocene exhumation of the Tuareg Shield (Sahara Desert, Africa). Geology, 41, 615–618. 8 9 708 SAHAGIAN, D. (1988) Epeirogenic motions of Africa as inferred from Cretaceous shoreline 10 11 709 deposits. Tectonics, 7, 125–138. 12 13 710 SALZE, D. (2008) Etude des interactions entre uranium et composés organiques dans les systèmes 14 15 711 hydrothermaux. PhD thesis, Université Henri Poincaré, Nancy, France. 16 17 712 SCHOENHERR, J., LITTKE, R., URAI, J., KUKLA, P. & RAWAHI, Z. (2007) Polyphase thermal 18 19 713 evolution in the Infra-Cambrian Ara Group (South Oman Salt Basin) as deduced by maturity of 20 21 714 solid reservoir bitumen. Org. Geochem., 38, 1293–1318. 22 23 715 SWEENEY, J. & BURNHAM, A. (1990) Evaluation of a simple model of vitrinite reflectance based 24 25 716 on chemical kinetics. AAPG Bull., 74, 1559–1570. 26 27 717 SWEZEY, C.S. (2009) Cenozoic stratigraphy of the Sahara, Northern Africa. J. Afr. Earth Sci., 53, 28 29 718 89–121. 30 31 719 THOMAS, M.F.H., BODIN, S., REDFERN, J. & IRVING, D.H.B. (2010) A constrained African 32 33 720 craton source for the Cenozoic Numidian Flysch: Implications for the paleogeography of the 34 35 721 western Mediterranean basin. Earth Sci. Reviews., 101, 1–23. 36 37 722 TURNER, P., PILLING, D., WALKER, D., EXTON, J., BINNIE, J. & SABAOU, N (2001) Sequence 38 39 723 stratigraphy and sedimentology of the late Triassic TAG-I (Blocks 401/402, Berkine Basin, 40 41 724 Algeria). Mar. Petrol. Geol., 18, 959-981. 42 43 725 TURNER, P. & SHERIF, H. (2007) A giant Late Triassic-Early Jurassic evaporitic basin on the 44 45 726 Saharan Platform, North Africa. In: Evaporites through space and time (Ed. by B.C. Schreiber, 46 47 727 S. Lugli & M. Babel), Geol. Soc. Lond., Spec. Publ., 285, 87–105. 48 49 728 UNDERDOWN, R. (2006) An integrated basin modelling study of the Ghadames Basin, North 50 51 729 Algeria. PhD thesis, University of Manchester, United Kingdom. 52 53 730 UNDERDOWN, R., REDFERN, J. & LISKER, F. (2007) Constraining the burial history of the 54 55 731 Ghadames basin, North Africa: an integrated analysis using sonic velocities, vitrinite reflectance 56 732 and apatite fission track ages. Basin Res., 19, 557–578. 57 58 27 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 28 of 41

1 2 3 733 WILSON, M. & GUIRAUD, R. (1992) Magmatism and rifting in Western and Central Africa, from 4 5 734 Late Jurassic to Recent times. Tectonophysics, 213, 203–225. 6 7 735 WILSON, M., GUIRAUD, R., MOREAU, C. & BELLION, Y.J.C. (1998) Late Permian to Recent 8 9 736 magmatic activity on the African-Arabian margin of Tethys. In: Petroleum geology of North 10 11 737 Africa (Ed. by D.S. MacGregor, R.T.J. Moody & D.D. Clark-Lowes), Geol. Soc. Lond., Spec. 12 13 738 Publ., 132, 231–263. 14 15 739 WYGRALA, B.P. (1989) Integrated study of an oil field in the southern Po basin, northern Italy. 16 17 740 PhD thesis, Köln University, Research Centre Jülich, Germany. 18 19 741 YAHI, N., SCHAEFER, R.G. & LITTKE, R. (2001) Petroleum generation and accumulation in the 20 21 742 Berkine Basin, eastern Algeria. AAPG Bull., 85, 1439–1467. 22 23 743 YARMOLYUK, V.A. & KUZNETSOV, Y.Y. (1977) Geological map of Africa. Ministry of Geology 24 25 744 of the USSR, Moscow, Russia, scale 1:5,000,000, 9 sheets. 26 27 745 ZANGUINA, M., BRUNETON, A. & GONNARD, R. (1998) An introduction to the petroleum 28 29 746 potential of Niger. J. Petrol. Geol., 21, 83–103. 30 31 747 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 28 59 60 FOR REVIEW PURPOSES ONLY Page 29 of 41 Basin Research

1 2 3 748 List of Tables 4 5 6 749 Table 1: Vitrinite reflectance data from Well A, Illizi basin, Algeria. 7 8 750 Table 2: Rock-Eval pyrolysis data from Well A, Illizi basin, Algeria. 9 10 751 Table 3: Apatite fission-track data from Well A, Illizi basin, Algeria. 11 12 13 752 14 15 753 List of Figures 16 17 754 Figure 1: (A) Topographic map of North Africa showing the Hoggar and Aïr massifs, and 18 19 755 location of other Cenozoic volcanic areas including Tibesti and Darfur (Lesquer et al., 1988). (B) 20 21 756 Simplified geology map of the Hoggar and Aïr massifs and flanking sedimentary basins (adapted 22 757 from Yarmolyuk & Kuznetsov, 1977; Choubert & Faure-Muret, 1990; LeFranc & Guiraud, 23 24 758 1990; Genik, 1993). Dated Mesozoic sediments that unconformably overlie basement 25 26 759 (Serouenout and Amguid localities) are highlighted. Preserved Cenozoic sediments described in 27 28 760 the text are located in the Tademaït region. Location of Tin Fouyé Tabankort field (TFT) is noted 29 30 761 where post-Hercynian deposits are preserved. Other information includes locations of thermal 31 762 maturity data (Well A, Akouta and Arlit), new apatite fission track data (Well A), and published 32 33 763 apatite thermochronology sample sites (Hoggar, Aïr, Ahnet, Tihemboka, Qarqaf Arch). Note that 34 35 764 Logan and Duddy (1998) study includes both apatite fission track, and zircon fission track 36 37 765 analysis. Refer to Figure 7 for illustration of the north-south transect (A-A’) across the Hoggar 38 766 Massif into the flanking basins. 39 40 41 767 Figure 2: (A) Actual Well A thermal maturity data (black circles) versus modelled thermal 42 43 768 maturity profile (black line) according to depth. Models 1 and 2 maturity profiles are identical. 44 769 The default profile illustrates predicted maturity if no additional burial is assumed. Present-day 45 46 770 thermal maturity is higher than what would be expected from current burial depths (default 47 48 771 maturity profile shown by dashed red line) indicating that these rocks have been hotter in the 49 50 772 past. (B) Actual Well A fission-track ages (red circles) versus modelled fission-track ages (blue 51 773 squares, Model 1; red squares, Model 2) according to depth. Most modelled fission-track ages 52 53 774 for the actual grain populations for Models 1 and 2 overlie except for GC1085-2 (Visean). All 54 55 775 samples provide fission-track ages that are younger than their corresponding depositional ages, 56 57 58 29 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 30 of 41

1 2 3 776 and show a trend of decreasing fission-track age with depth due to greater degree of annealing. 4 5 777 The default profile illustrates the predicted fission-track ages for apatites with 0.1 wt.% chlorine 6 7 778 content if no additional burial is assumed. The measured fission-track ages are routinely younger 8 9 779 than the default profile, consistent with the interpretation that this stratigraphic sequence has 10 11 780 experienced hotter temperatures in the past. The predicted profile from the preferred Well A 12 781 model (Model 1), also assuming a chlorine content of 0.1 wt.%, provides a much better fit to the 13 14 782 data. Samples with higher chlorine contents will be more resistant to annealing for a given 15 16 783 thermal history. Fission-track modelling was carried out with HeFTy using the annealing kinetics 17 18 784 of Ketcham et al. (2007). 19 20 785 Figure 3: Inverse modelling of the (A) Namurian sample GC1085-1 and the (B) deeper 21 22 786 Devonian-Silurian sample combined from GC1085-6, GC1085-7 and GC1085-8. The models 23 24 787 were run until 10,000 good paths were identified. The vertices of the good paths (GOF > 0.5) are 25 26 788 highlighted in purple, while the vertices of the acceptable paths (GOF > 0.05) are highlighted in 27 789 green. The best-fit of all the inverse model solutions is highlighted by the black line in the 28 29 790 thermal history plot. These solutions are non-unique and simply represent the best-fit of 10,000 30 31 791 different thermal histories that can provide a good fit to the measured data. 32 33 792 Figure 4: 1D thermal history models for Well A calibrated to thermal maturity and fission-track 34 35 793 data. (A) Model 1 assumes maximum burial during the Eocene. (B) Model 2 assumes maximum 36 37 794 burial during the Middle Cretaceous at the Austrian tectonic event. Additionally, slightly more 38 39 795 Carboniferous deposition in Model 2 (50m) with 25m less Hercynian erosion was required to 40 796 best match maturity. While these solutions are non-unique, the new data require significant 41 42 797 additional burial to match the peak paleotemperature constraints, followed by the onset of 43 44 798 significant exhumation during the Eocene. Thermal history modelling was carried out using 45 46 799 Genesis. 47 48 800 Figure 5: Temperature-time (T-t) histories from Model 1 for (A) the Namurian sample 49 50 801 (GC1085-1) and (B) the combined Devonian-Silurian samples (GC1085-6, GC1085-7 and 51 52 802 GC1085-8) exported from Genesis into HeFTy. Forward modelling of the T-t pathways in 53 54 803 HeFTy provide a very good fit (GOF > 0.85) for the track length distribution in both samples and 55 804 for the fission-track age in the Devonian-Silurian samples. The goodness-of-fit is lower for the 56 57 58 30 59 60 FOR REVIEW PURPOSES ONLY Page 31 of 41 Basin Research

1 2 3 805 fission-track age in the Namurian sample and this may be due to preservation of pre-depositional 4 5 806 inheritance as this sample was not fully annealed during burial. 6 7 807 Figure 6: Temperature-time (T-t) histories from Model 2 for (A) theNamurian sample (GC1085- 8 9 808 1) and (B) the combined Devonian-Silurian samples (GC1085-6, GC1085-7 and GC1085-8) 10 11 809 exported from Genesis into HeFTy. Forward modelling of the T-t pathways in HeFTy provide a 12 13 810 very good fit (GOF > 0.85) for the track length distribution in both samples and for the fission- 14 15 811 track age in the Devonian-Silurian samples. The goodness-of-fit is lower for the fission-track age 16 812 in the Namurian sample and this may be due to preservation of pre-depositional inheritance as 17 18 813 this sample was not fully annealed during burial. 19 20 814 Figure 7: Schematic structural section across the Hoggar Massif from the Berkine Basin in the 21 22 815 north to the Iullemmeden Basin in the south (see transect in Fig. 1). Note that the Hoggar had an 23 24 816 earlier history of uplift with significant erosion of the Paleozoic sequence during the Hercynian 25 26 817 orogeny. Preserved thicknesses are taken from well data (Illizi-Berkine), geology maps and 27 28 818 published cross sections (Iullemmeden Basin, Zanguina et al., 1998; Genik, 1993; Dautria & 29 819 Lesquer, 1989). The eroded stratigraphy of the Tim Mersoï, Hoggar and Illizi regions is 30 31 820 projected above the present day surface and calibrated to ~ 1 km of exhumation in Well A, ~ 0.9- 32 33 821 1.6 km exhumation in the Serouenout area, and peak burial depths of ~ 1.7-2.3 km for the Visean 34 35 822 projected from the Arlit area. Note that the actual magnitude of exhumation in Arlit/Arouta (on 36 823 the flank of Aïr; Fig. 1) is higher than where it is projected on this section (Carboniferous at 37 38 824 surface). Regional data suggests portions of the Central Hoggar may have been inundated with > 39 40 825 1 km of Upper Cretaceous – lower Paleogene sediment. Cenozoic rock uplift across the Hoggar 41 42 826 occurred over a distance of >1,500 km from north to south, as indicated by the tilted Cenozoic 43 827 stratigraphy in the Berkine and Iullemmeden basins. The magnitude of rock uplift, as opposed to 44 45 828 exhumation, reaches in excess of 2 km within the core of the Hoggar Massif. Deposition of 46 47 829 Upper Eocene-Pliocene sediments (the “Continental Terminal”) across Saharan Africa (Kilian, 48 49 830 1931) may represent the onset of clastic sedimentation derived from the growing intracratonic 50 51 831 swells. 52 53 54 55 56 57 58 31 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 32 of 41

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 Figure 1: (A) Topographic map of North Africa showing the Hoggar and Aïr massifs, and location of other Cenozoic volcanic areas including Tibesti and Darfur (Lesquer et al., 1988). (B) Simplified geology map of 48 the Hoggar and Aïr massifs and flanking sedimentary basins (adapted from Yarmolyuk & Kuznetsov, 1977; 49 Choubert & Faure-Muret, 1990; LeFranc & Guiraud, 1990; Genik, 1993). Dated Mesozoic sediments that 50 unconformably overlie basement (Serouenout and Amguid localities) are highlighted. Preserved Cenozoic 51 sediments described in the text are located in the Tademaït region. Location of Tin Fouyé Tabankort field 52 (TFT) is noted where post-Hercynian deposits are preserved. Other information includes locations of thermal 53 maturity data (Well A, Akouta and Arlit), new apatite fission track data (Well A), and published apatite 54 thermochronology sample sites (Hoggar, Aïr, Ahnet, Tihemboka, Qarqaf Arch). Note that Logan and Duddy 55 (1998) study includes both apatite fission track, and zircon fission track analysis. Refer to Figure 7 for illustration of the north-south transect (A-A’) across the Hoggar Massif into the flanking basins. 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Page 33 of 41 Basin Research

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 Figure 2: (A) Actual Well A thermal maturity data (black circles) versus modelled thermal maturity profile 39 (black line) according to depth. Models 1 and 2 maturity profiles are identical. The default profile illustrates 40 predicted maturity if no additional burial is assumed. Present-day thermal maturity is higher than what 41 would be expected from current burial depths (default maturity profile shown by dashed red line) indicating 42 that these rocks have been hotter in the past. (B) Actual Well A fission-track ages (red circles) versus 43 modelled fission-track ages (blue squares, Model 1; red squares, Model 2) according to depth. Most 44 modelled fission-track ages for the actual grain populations for Models 1 and 2 overlie except for GC1085-2 (Visean). All samples provide fission-track ages that are younger than their corresponding depositional ages, 45 and show a trend of decreasing fission-track age with depth due to greater degree of annealing. The default 46 profile illustrates the predicted fission-track ages for apatites with 0.1 wt.% chlorine content if no additional 47 burial is assumed. The measured fission-track ages are routinely younger than the default profile, consistent 48 with the interpretation that this stratigraphic sequence has experienced hotter temperatures in the past. The 49 predicted profile from the preferred Well A model (Model 1), also assuming a chlorine content of 0.1 wt.%, 50 provides a much better fit to the data. Samples with higher chlorine contents will be more resistant to 51 annealing for a given thermal history. Fission-track modelling was carried out with HeFTy using the annealing kinetics of Ketcham et al. (2007). 52 53 54 55 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 34 of 41

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Figure 3: Inverse modelling of the (A) Namurian sample GC1085-1 and the (B) deeper Devonian-Silurian 46 sample combined from GC1085-6, GC1085-7 and GC1085-8. The models were run until 10,000 good paths 47 were identified. The vertices of the good paths (GOF > 0.5) are highlighted in purple, while the vertices of 48 the acceptable paths (GOF > 0.05) are highlighted in green. The best-fit of all the inverse model solutions is 49 highlighted by the black line in the thermal history plot. These solutions are non-unique and simply represent the best-fit of 10,000 different thermal histories that can provide a good fit to the measured data. 50 51 52 53 54 55 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Page 35 of 41 Basin Research

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 Figure 4: 1D thermal history models for Well A calibrated to thermal maturity and fission-track data. (A) Model 1 assumes maximum burial during the Eocene. (B) Model 2 assumes maximum burial during the 48 Middle Cretaceous at the Austrian tectonic event. Additionally, slightly more Carboniferous deposition in 49 Model 2 (50m) with 25m less Hercynian erosion was required to best match maturity. While these solutions 50 are non-unique, the new data require significant additional burial to match the peak paleotemperature 51 constraints, followed by the onset of significant exhumation during the Eocene. Thermal history modelling 52 was carried out using Genesis. 53 54 55 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 36 of 41

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Figure 5: Temperature-time (T-t) histories from Model 1 for (A) the Namurian sample (GC1085-1) and (B) 46 the combined Devonian-Silurian samples (GC1085-6, GC1085-7 and GC1085-8) exported from Genesis into 47 HeFTy. Forward modelling of the T-t pathways in HeFTy provide a very good fit (GOF > 0.85) for the track 48 length distribution in both samples and for the fission-track age in the Devonian-Silurian samples. The 49 goodness-of-fit is lower for the fission-track age in the Namurian sample and this may be due to preservation of pre-depositional inheritance as this sample was not fully annealed during burial. 50 51 52 53 54 55 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Page 37 of 41 Basin Research

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 Figure 6: Temperature-time (T-t) histories from Model 2 for (A) theNamurian sample (GC1085-1) and (B) the combined Devonian-Silurian samples (GC1085-6, GC1085-7 and GC1085-8) exported from Genesis into 47 HeFTy. Forward modelling of the T-t pathways in HeFTy provide a very good fit (GOF > 0.85) for the track 48 length distribution in both samples and for the fission-track age in the Devonian-Silurian samples. The 49 goodness-of-fit is lower for the fission-track age in the Namurian sample and this may be due to 50 preservation of pre-depositional inheritance as this sample was not fully annealed during burial. 51 52 53 54 55 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Basin Research Page 38 of 41

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Figure 7: Schematic structural section across the Hoggar Massif from the Berkine Basin in the north to the 22 Iullemmeden Basin in the south (see transect in Fig. 1). Note that the Hoggar had an earlier history of uplift 23 with significant erosion of the Paleozoic sequence during the Hercynian orogeny. Preserved thicknesses are 24 taken from well data (Illizi-Berkine), geology maps and published cross sections (Iullemmeden Basin, 25 Zanguina et al., 1998; Genik, 1993; Dautria & Lesquer, 1989). The eroded stratigraphy of the Tim Mersoï, Hoggar and Illizi regions is projected above the present day surface and calibrated to ~ 1 km of exhumation 26 in Well A, ~ 0.9-1.6 km exhumation in the Serouenout area, and peak burial depths of ~ 1.7-2.3 km for the 27 Visean projected from the Arlit area. Note that the actual magnitude of exhumation in Arlit/Arouta (on the 28 flank of Aïr; Fig. 1) is higher than where it is projected on this section (Carboniferous at surface). Regional 29 data suggests portions of the Central Hoggar may have been inundated with > 1 km of Upper Cretaceous – 30 lower Paleogene sediment. Cenozoic rock uplift across the Hoggar occurred over a distance of >1,500 km 31 from north to south, as indicated by the tilted Cenozoic stratigraphy in the Berkine and Iullemmeden basins. 32 The magnitude of rock uplift, as opposed to exhumation, reaches in excess of 2 km within the core of the Hoggar Massif. Deposition of Upper Eocene-Pliocene sediments (the “Continental Terminal”) across Saharan 33 Africa (Kilian, 1931) may represent the onset of clastic sedimentation derived from the growing intracratonic 34 swells. 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 FOR REVIEW PURPOSES ONLY Page 39 of 41 Basin Research

1 2 3 Table 1: Vitrinite reflectance data from Well A, Illizi basin, Algeria 4 5 Vitrinite Depth Interval Bitumen or Peak Paleo- 6 Ro Sample Reflectance Vit. Refl. Well Analyst Formation Chitinozoan Std Dev temperature 7 Indicator Count Ro-Random Equiv. From (m) To (m) Reflectance (°C) 8 (*Ro-Max) 9 Well A EGS Namurian 195 350 V 8 0.63 - 0.07 - 104 10 Well A EGS Visean C 450 540 V 12 0.62 - 0.07 - 102 11 Well A KK Tournaisian 720 770 V 10 (0.61*) - 0.05 - 101 12 Well A EGS Tournaisian 800 885 V 9 0.62 - 0.04 - 102 13 Well A EGS Devonian F2 990 1105 V 10 0.67 - 0.05 - 110 14 Well A EGS Devonian MPR 1110 1205 V 7 0.69 - 0.03 - 113 15 Well A EGS Devonian F3 1235 1330 V 14 0.72 - 0.07 - 117 16 Well A KK Devonian F4 1330 1350 V 13 (0.67*) - 0.05 - 110 17 Well A EGS Upper Silurian 1665 1800 B 8 - 0.78 0.05 0.97 142 18 Well A EGS Lower Silurian 1800 1900 B 9 - 0.84 0.07 1.03 146 19 NOTE: Reflectance data from Well A cuttings was measured by two different contractors (KK = Keiraville Konsultants and EGS = Egs-ploration). No sample count 20 exceeds 14 measurements due to limited sample volume, so maturity estimates must be treated with some caution. Only samples with > 5 measurements are provided 21 here. Measured indicators V= vitrinite; B = bitumen. Measured bitumen reflectance was converted to Ro% equivalent using equation from Schoenherr et al. (2007): 22 [R vit = (R bit + 0.2433) / 1.0495 ]. Vitrinite reflectance (and equivalents) were converted to an estimate of peak paleo-temperature assuming a heating rate of 1 °C/Myr 23 (Sweeney & Burnham, 1990). 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 FOR REVIEW PURPOSES ONLY 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Basin Research Page 40 of 41

1 2 3 Table 2: Rock-Eval pyrolysis data from Well A, Illizi basin, Algeria 4 5 Depth (m) TOC S S S T HI OI GP Calc. Well Formation 1 2 3 max PI 6 From To (wt.%) mgHC/grock mgHC/grock mgHC/grock °C mgHC/gTOC mgCO2/gTOC mgHC/grock Ro% eqv. 7 Well A Devonian F2 Shale 990 1105 1.67 0.39 3.92 0.64 438 235 38 4.31 0.09 0.72 8 Well A Devonian MPR 1110 1205 1.69 0.65 4.52 0.57 439 267 34 5.17 0.13 0.74 9 Well A Devonian F3 1235 1330 1.26 0.5 3.29 0.46 445 261 37 3.79 0.13 0.85 10 NOTE: T to Ro% conversion from Jarvie et al. (2001) and Peters et al. (2005): [Ro% eqv=(0.018*T ) - 7.16 ]. Rock-Eval data were screened 11 max max according to criteria of English et al. (2015) and Peters & Cassa (1994). TOC: total organic carbon; HI: hydrogen index; OI: oxygen index; GP: genetic 12 13 potential; PI: production index 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 FOR REVIEW PURPOSES ONLY 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 41 of 41 Basin Research

1 2 3 Table 3: Apatite fission-track data from Well A, Illizi Basin, Algeria 4 Sample Stratigraphic Present Day No. of Spontaneous Induced Dosimeter F.T. Age Mean Track Std. No. of 5 Formation Depth (m) P(χ2) number Age (Ma) Temp. (°C) grains (Ma ± 1σ) Length (μm) dev. tracks 6 ρs N s ρi N i ρD N D 7 GC1085-1 Namurian 326 - 315 160-200 29 21 1.080 477 1.071 473 11.7% 1.449 2283 281 ± 20 12.09 ± 0.16 1.65 106 8 GC1085-2 Visean B 347 - 331 600-630 46 6 1.104 98 2.919 259 6.3% 1.450 2283 107 ± 13 10.48 ± 0.68 1.51 5 9 GC1085-6 Devonian F6C3 406 - 400 1385-1425 76 10 0.370 64 3.646 631 88.5% 1.452 2283 28.9 ± 3.9 10.57 ± 1.45 3.25 5 10 GC1085-7 Devonian F6C1 417 - 410 1445-1500 79 8 0.274 55 3.069 616 4.4% 1.452 2283 25.4 ± 3.6* 9.79 ± 0.51 1.60 10 11 GC1085-8 Silurian F6A 423 - 418 1535-1560 82 19 0.180 73 3.030 645 16.1% 1.453 2283 16.9 ± 2.1 10.75 ± 0.41 2.08 26 12 GC1085-9 Silurian F6M1 426 - 423 1620-1660 85 11 0.464 61 6.478 852 5.6% 1.454 2283 20.4 ± 2.8 11.06 ± 0.41 1.89 21 13 GC1085-10 Ordovician Unit IV 444 - 439 1915-2117 99 18 0.109 35 3.234 1038 4.4% 1.455 2283 9.6 ± 1.7* 12.59 ± 0.60 2.09 12 14 GC1085-6, -7, -8 Combined 423 - 400 1385-1560 79 37 0.246 192 3.177 2477 5.2% 1.452 2283 22.1 ± 1.8 10.49 ± 0.33 2.12 41 15 6 -2 6 -2 16 NOTE: ρs - spontaneous track density (×10 cm ) measured in internal mineral surfaces; ρi and ρD - induced and dosimeter track density (×10 cm ) on external mica detectors; N s, N i and N D - number of 17 spontaneous, induced tracks and total number of tracks; P(χ2) - probability of obtaining χ2 value for degrees of freedom (where ν = number of crystals – 1). The presented fission-track ages are pooled ages 18 commonly used when P(χ2) > 5% (Galbraith & Laslett, 1993). The two samples with P(χ2) < 5% have central ages of 29.7±5.9 Ma (GC1085-7 ) and 8.5±2.4 Ma (GC1085-10 ). 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 FOR REVIEW PURPOSES ONLY 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60