R Ghalayini

Bou Daher

Extensive 3D seismic data offshore Lebanon together with new investigations of 12 Page 1 of 78 For review only Journal of Petroleum Geology structural and geochemical investigations to propose a summary of the potential 25 petroleum systems for each domain, on the eve of Lebanon first offshore 26 licensing round. 27 Page 2 of 78 For review only Journal of Petroleum Geology

. This has 53 resulted in the development of a new basin model for Lebanon and its offshore 54 based on an integration of all the newly acquired knowledge, providing an 55 updated picture of the hydrocarbon potential of Lebanon (Bou Daher et al., 56 2016). In addition, a refined model for the crustal structure of the Levant Basin 57 was proposed (Inati et al., 2016), which directly impacts the petroleum systems 58 and the source rock maturity. 59 60 This article summarizes the results of the latest geological and petroleum 61 investigations in Lebanon and adds new up-to-date data -especially with regard 62 to potential petroleum systems. First, it presents new interpretation of the 63 Levant margin offshore Lebanon since the carbonate prospects have attracted 64 major attention following the Zohr discovery in carbonate reservoirs offshore 65 Egypt. Second, it subdivides the region into geological domains based on 66 multitude of stratigraphic, structural and geochemical data. Third, it discusses 67 the various petroleum aspects of each domain (potential source rocks, 68 reservoirs, and traps) and points out new objectives based on recent data and 69 neighboring discoveries. These results serve as a basis for the understanding of 70 the petroleum potential of Lebanon and provide a good case study on 71 exploration effectiveness and strategy at a critical time as the first offshore 72 licensing round has been set.

the onshore domain have resulted in a considerable wealth of information on the 13 regional geology and petroleum prospectivity. This article presents a new 14 interpretation of the Levant margin offshore Lebanon with an up-to-date review 15 of the geology of Lebanon and a new comprehensive insight on the petroleum 16 systems along the Eastern Mediterranean sector. The Lebanese onshore and 17 offshore territories are separated in this study into four different domains: the 18 deep basin, the Lattakia Ridge, the Levant margin and the onshore. Each of these 19 domains is marked by a general structural style and various stratigraphic 20 architectures, resulting in different source-reservoir-trap configurations. The 21 new subdivision impacts exploration as it highlights specific geographic areas 22 having distinct petroleum systems. This study takes into account all previously 23 published geological knowledge and provides new results from stratigraphic, Introduction 28 Lebanon, part of the larger Levant region, is located in the NW part of the 29 Arabian plate along its western active boundary with Africa (fig. 1). This area is 30 marked by the passage of the Levant Fracture System (LFS), the fold and thrust 31 belt of the Palmyrides ranges to the east and the stable foreland Levant basin to 32 the west. Lebanon and its offshore are considered as a promising petroleum 33 province as a result of more than 70 tcf of proven natural gas reserves in nearby 34 countries, following the discovery of Tamar, Leviathan, Aphrodites andZohr 35 between 2006 and2015 (fig. 2). Onshore, recoverable reserves of Syria are 36 estimated at about 2.5 billion bbl of oil and about 8.5 TCF of gas, with productive 37 fields in the Palmyrides, the Euphrates graben and the Sinjar high (Barrier et al., 38 2014). 39 40The latest petroleum activities in the Levant and the promising potential of 41

Lebanon have prompted the Lebanese government to acquire an extensive 42 amount of multiclient 3D seismic data to aid exploration offshore. Improved 43 knowledge of the geology of the Levant region was achieved by using this 44 unprecedented wealth of information and seismic data coverage and by 45 attracting considerable academic and industrial research projects, referenced 46 herein. A new model for the stratigraphic setting and filling of the basin has been 47 (Le Pichon and Kreamer, 2010;[START_REF] Sengor | Tethyan evolution of Turkey: a plate 1413 tectonic approach[END_REF]. It has directly affected 122 the Lattakia Ridge which was reactivated into a sinistral strike-slip motion (Hall 123 et al., 2005). These geodynamic events were marked in both the Levant Basin 124 and onshore Lebanon by reactivation of structures, and a decrease in the lateral 125 motion of the LFS [START_REF] Freund | The Shear along the Dead Sea Rift [and Discussion[END_REF][START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]Le Pichon and 126 Gaulier, 1988;Quennell, 1984). It is also at this time, that the accelerated uplift of 127 the pre-existing Lebanese structures took place [START_REF] Walley | Some outstanding issues in the geology of Lebanon and 1436 their importance in the tectonic evolution of the Levantine region[END_REF]Ghalayini et al., 128 2017;[START_REF] Beydoun | Evolution and development of the Levant (Dead Sea Rift) 1114 transform system: a historical-chronological review of a structural controversy[END_REF]. 129 130The thickness of the crust gradually decreases westward from the Palmyrides to 131 the Levant Basin, with 44 km in the SW Palmyrides, 35 km beneath the anti-132

Lebanon ranges and 27 km beneath Mount Lebanon [START_REF] Brew | Tectonic 1135 and Geologic Evolution of Syria[END_REF]Khair et 133 al., 1993). This westward thinning of the crust beneath Syria and Lebanon 134 indicates a transition between a crust of continental type east of the Levant 135 margin, transitioning to a thinned continental crust of 8-10 km thickness 136 beneath the Levant Basin as evidenced by modern gravity inversion (Inati et al., 137 2016) and refraction seismic profiles [START_REF] Ben-Avraham | Crustal 1103 structure of the Levant Basin, eastern Mediterranean[END_REF]Makris et al., 138 1983;Netzeband et al., 2006). This gradual, smooth thickness transition is the 139 result of the Permo-Jurassic rifting of Pangea, causing the break-off of 140 continental blocks from the Afro-Arabian plate to form the Neo-Tethys ocean 141 [START_REF] Garfunkel | Constrains on the origin and history of the Eastern 1225 Mediterranean basin[END_REF]Robertson, 1998) and pointing to successive regimes of 142 extension that did not reach a real break up stage. 143 variations and following the interpretation of [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF] (fig. 3). Horizon 157 RN1 separates non-continuous and low amplitude reflectors from the overlying 158 semi-continuous and relatively brighter package. The latter is exhibiting growth 159 strata and fanning geometries. RN2 is a continuous very bright reflector with a 160 strong impedance contrast. Toward the deep basin, it separates a set of bright 161 and stacked continuous reflectors package from non-continuous and dim 162 reflectors. RN3 marks the top of a series of three stacked reflectors package in 163 the east. To the west of the line, it forms an angular unconformity surface in 164 which the underlying unit is truncated. The overlying reflectors also exhibit 165 relatively lower amplitudes. RN4 exhibits a strong impedance contrast and 166 separate chaotic reflectors above from the stacked and bright reflectors below. 167 RN5 is a continuous horizon with a strong impedance contrast marking the top 168 of the low amplitude unit to the east from more continuous and bright reflectors 169 above. It continues westward to the deep basin in which it is still marked by a 170 strong impedance contrast. Horizons RN6 to RN11 were picked up based on the 171 interpretation of Hawie et al. (2014). 172 173 The unit between RN2 and RN3 exhibits significant seismic facies variation 174 toward the deep basin in which continuous semi-bright reflectors appear to be 175 transitioning to chaotic reflectors in the middle. Further west, the unit is 176 dominated by a series of stacked and bright reflectors. Similar observations can 177 be made on the unit between RN3 and RN5 to the east in which the reflectors 178 become chaotic in the centre of the line and the overall unit adopts a wedge 179 shape geometry. 180 181 Interpretation 182

Methods and data

183

The fan-shaped geometry of reflectors between RN1 and RN2 point to the 184 presence of growth strata suggesting that normal faults are present at this depth. 185

The latter are NE trending parallel to the coastline and are dipping to the NW. 186 Similar extensional structures are documented in the southern Levant and 187 believed to have nucleated during the Triassic as a result of Tethyan rifting (e.g. 188 [START_REF] Gardosh | Tethyan rifting in the Levant Region and its role in Early Mesozoic crustal 1210 evolution[END_REF]. Therefore, units below RN1 are likely the pre-rift package 189 while units between RN1 and RN2 are the syn-rift package. This could be 190 attributed to the Permian and Triassic-Lower Jurassic units respectively. As RN2 191 is not displaced by faulting and separates deformed units below from non-192 deformed units above, it could correspond to the break-up unconformity of mid-193 Jurassic age [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. RN2 therefore marks the initiation of tectonic 194 Lebanon (Nader et al., 2016;[START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF] and is conformable with the 199 seismic facies interpretation of [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF] Hauterivian. The overlying wedge-shape of the unit and the chaotic reflectors 213 associated could represent mass transport deposits or carbonate talus 214 originating from the Cretaceous carbonate succession along the margin and 215 onshore [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. RN5 horizon corresponds to a major marine 216 onlapping surface and therefore could represent the Senonian unconformity 217 horizon [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF][START_REF] Gardosh | The sequence stratigraphy of 1215 Mesozoic successions in the Levant margin, southwestern Israel: A model for the 1216 evolution of southern Tethys margins[END_REF]. On top of the Senonian 218 unconformity, the high amplitude package should be Tertiary in age as it overlies 219 it is believed to be the Senonian unconformity horizon (e.g. [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]. 268

Page 11 of 78

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The thickness between RS3 and RS2 is 1.5 to 2 Km, slightly higher than the total 269 expected thickness of the Jurassic unit south of Lebanon (Nader et al., 2016;270 Dubertret, 1955). Horizon RS2 exhibits a strong impedance contrast, probably 271 indicating a transition between primarily dolomite succession to evaporites. 272 Therefore, RS2 is likely the top of the mid Triassic. The thickness between RS2 273 and RS1 is 1 to 1.5 km in accordance with the expected thickness of the Triassic 274 in Lebanon (Nader et al., 2016;[START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF] and therefore RS1 is 275 likely the base Triassic. This interpretation points to an extension of the broad 276 geometries observed onshore to the Levant margin offshore with possible lateral 277 facies changes expected away from the coast. 278

279

The interpretation of the Tertiary units is adopted from [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF] The large vertical displacement observed on the ENE trending northern 294 bounding fault, referred to as the Saida fault, is likely related to an old Mesozoic 295 extensional regime. [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF] argues that this fault is reactivated 296 into a dextral strike-slip in the Late Miocene due to the en-echelon anticlines 297 observed in the upper Miocene unit. Onshore, the Saida fault is correlated with 298 the passage of the Damour fault zone, which consists of a deformation zone of are the westward continuation of the Jhar fault in Syria due to the similar trend, 302 evolution history and crustal configuration north and south of these faults 303 (Ghalayini et al., 2017). Therefore, it is likely that the STP also marks a crustal 304 transition and could be underlain by a continental crust (e.g. Ghalayini et al., 305 2014). The western bounding faults displace vertically the Mesozoic unit for 306 more than 2 km, also suggesting an older extensional episode prior to the 307 Cenozoic. The positive flower structures and the folding in the Tertiary units 308 might indicate a transpressive regime starting in the Late Miocene times. The 309 ENE-WSW to ESE-WNW normal faults documented at the easternmost STP (fig. 310 5) are similar to faults well documented in southern Mount Lebanon (Homberg 311 et al., 2009;Homberg et al., 2010). It is very likely that these faults belong to the 312 same fault family as the ones documented onshore and therefore were active 313 during the Cretaceous times (e.g. Homberg et al. 2009) 314 [START_REF] Gardosh | Seismic strati-graphy, structure and 1201 tectonic evolution of the Levantine basin, offshore Israel[END_REF]331 Hawie et al., 2013;Roberts and Peace, 2007). The main structural features 332 prevalent in this domain are the normal faults and the NE trending anticlines. 333 334 Stratigraphic setting 335 336 Nine horizons were identified in the Levant basin offshore Lebanon in seismic 337 data and correlated with nearby wells [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF] [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. The Oligo-Miocene units consist of siliciclastic 354 materials deposited as a result of marginal uplift and sea-level lowstands during 355 the late Eocene and Oligocene [START_REF] Haq | Phanerozoic cycles of sea-level change 1276 on the Arabian Platform Rationale for an Arabian Platform Cycle Chart[END_REF] which have led to 356 erosion on the margin and clastic deposition in the basin [START_REF] Gardosh | The Oligo-1205 Miocene deepwater system of the Levant Basin[END_REF]. 357 [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF] documented the presence of canyons incising the margin 358 within the middle-upper Miocene offshore northern Lebanon, together with 359 various characteristics of deep-water sedimentary environments such as 360 channels, levees and sheeted turbidite lobes towards the distal basin. 361

Main geological domains

362

The thick Oligo-Miocene succession in the Levant Basin can be explained by 363 considerable sedimentary flux originating from a proto Nile (Steinberg et al., 364 2011) in which distal turbidites and basin floor fans could extend as far as the 365

Page 15 of 78 For review only Journal of Petroleum Geology offshore Lebanon [START_REF] Dolson | Key Challenges 1171 to realizing full potential in an emerging giant gas province: Nile 1172 Delta/Mediterranean offshore, deep water, Egypt[END_REF][START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]. However, it was 366 shown that a multi-source system better describes the filling of the basin based 367 on forward stratigraphic modelling constrained by seismic, well and field data 368 [START_REF] Hawie | Multi-scale constraints of sediment 1292 source to sink systems in frontier basins: a forward stratigraphic modeling case 1293 Page 53 of 78 For review only[END_REF]. Therefore, it is most likely that the filling was also 369 accomplished by erosion from the eastern margin together with provenance of 370 sediments from the north, mainly from the Lattakia region in Syria. Overlying the 371 Oligo-Miocene, the Messinian unit is a ~1.7 km thick evaporitic sequence 372 deposited as a result of the sequestration of the Mediterranean Sea at the end of 373 the Miocene and contains mass transport complexes at the base, clastic materials 374 intercalations and halite [START_REF] Gorini | New imaging of the 1261 salinity crisis: Dual Messinian lowstand megasequences recorded in the deep 1262 basin of both the eastern and western Mediterranean[END_REF]. A return to a pelagic/hemi-pelagic 375 sedimentation is attested during the Pliocene with the deposition of deep-water 376 turbidites in the basin [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]. 377 378 Structural setting 379 380 NE trending anticlines are documented in the deep basin and are 5 to 15 km long 381 structures deforming the Oligo-Miocene units only and detaching in the Eocene 382 unit (fig. 9). [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF] argues that these anticlines were folded 383 immediately prior to, or at the onset of the Messinian salinity crisis due to 384 absence of growth strata in the pre-Messinian units, and erosion of the anticlinal 385 crest along the base Messinian horizon. They were formed due to regional 386 geodynamics caused by the collision and suturing of Arabia with Eurasia. In the 387 southern Levant, similar trending anticlines were formed and are overlying 388 deep-seated Mesozoic extensional structures [START_REF] Gardosh | Seismic strati-graphy, structure and 1201 tectonic evolution of the Levantine basin, offshore Israel[END_REF] structures, but thickness variations below the ones found closer to the margin 391 strongly suggest so [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]. 392 393The normal faults are layer bound, found ubiquitously in the Oligo-Miocene units 394 in the deep basin. The faults are regularly spaced with a dip of 60° either to the 395 NE or SW. At depth, all the faults consistently die out at the same intra-Eocene 396 detachment level (fig. 10), which has been interpreted to have a regionally 397 developed shale sequence acting as the basal detachment surface for these faults 398 [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF][START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]Kosi et al., 2012). As there is no NE-399 SW extension documented in the basin during the Oligo-Miocene, an exclusive 400 tectonic origin for their formation or a nucleation model in relation to the 401 Messinian Salinity Crisis (MSC) has been refuted [START_REF] Ghalayini | Growth of 1238 layer-bound normal faults under a regional anisotropic stress field[END_REF]. Detailed 402 analysis of the fault growth and evolution have showed that they have nucleated 403 during the Early Miocene and remained syn-sedimentary till the Late Miocene 404 [START_REF] Ghalayini | Growth of 1238 layer-bound normal faults under a regional anisotropic stress field[END_REF]. A likely nucleation mechanism for these faults could be 405 related to diagenetic reactions in the Oligo-Miocene units leading to volumetric 406 contraction of the host rock and causing intra-formational normal faulting (e.g. 407 [START_REF] Cartwright | Diagenetically induced shear failure of fine-grained 1145 sediments and the development of polygonal fault systems[END_REF][START_REF] Davies | Differential 1166 compaction due to the irregular topology of a diagenetic reaction boundary : a 1167 new mechanism for the formation of polygonal faults[END_REF][START_REF] Wrona | coast of northern Lebanon consisting mainly of a carbonate succession. The Triassic contains extensional normal faults in relation to the Triassic breakup of Pangea and the Early Cretaceous clastics are pinching out on the Jurassic carbonate talus deposits[END_REF]. 408

The Lattakia Ridge The Late Cretaceous convergence has resulted in a depocenter in the lower 421

Tertiary in this region evidenced by thicker Eocene and Oligocene units south 422 and south-east of the Lattakia Ridge [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]. The Miocene unit, 423 however, is thinning considerably and reaches up to 1 km in total thickness. It is 424 suggested that the proximity to a northern sedimentary source, i.e. from Syria, 425 could result in coarser sediment and more clastic material in the Oligo-Miocene 426 unit of this domain, possibly pointing to better reservoir qualities (Hawie et al., 427 2015). 428 been initiated during the Pliocene as a result of transpression [START_REF] Hall | Structural evolution 1266 of the Latakia Ridge and Cyprus Basin at the front of the Cyprus Arc , Eastern 1267 Mediterranean Sea[END_REF]440 Symeou et al., in review). This complex structural style of the Lattakia Ridge is a 441 result of the geodynamic setting of the Eastern Mediterranean region discussed 442

above. 443

The Levant margin Lebanon and the Bekaa Valley) as the depositional setting and associated 454 petroleum systems are expected to be different [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]Bou Daher et 455 al., 2016;[START_REF] Bou Daher | Geochemical 1124 and petrographic characterization of Campanian -Lower Maastrichtian 1125 calcareous petroleum source rocks of Hasbayya, South Lebanon[END_REF]Nader, 2014). 456 457

Stratigraphic setting 458 459

Interpretation of the stratigraphy along the Levant margin is provided by Hawie 460 et al. (2013), in which they correlate the units identified in seismic data to those 461 documented onshore [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF][START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]Nader, 2011). An 462 updated interpretation of the expected stratigraphy of Levant margin is provided 463 in the previous section of this manuscript. 464 465

Structural setting 466 467

The structures of the southern Levant margin were described in the previous 468 section. They show an analogy with those described by [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF] Cretaceous strata onshore adjacent to this location [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF], in contrast 475 with the broad plateau documented along the southern margin (Homberg et al., 476 2010;[START_REF] Hancock | Tectonic significance of mesofracture 1271 systems associated with the Lebanese segment of the Dead Sea transform fault[END_REF]). In the north, the Tertiary units gently onlap the 477 Mesozoic succession and the overall margin is cross-cut by E-W trending dextral 478 strike-slip faults. En-echelon anticlines, oriented NE-SW, are documented in the 479 Upper Miocene unit along the strike of these strike-slip faults. Several NNE 480 trending Mesozoic normal faults are documented in the Permo-Triassic units and 481 could be related to the Mesozoic rifting event [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]. 482

The onshore domain the margins of the Levant and the Palmyra Basins, which have similar ages and 487 tectonic histories (Ghalayini et al., 2017;Nader, 2014). Therefore, it has been 488 stated that the Lebanese ranges are part of the Palmyra Basin due to the large 489 resemblance between the structural features, the similar crustal configuration 490 and the analogous stratigraphic intervals (Ghalayini et al., 2017;Beydoun and 491 Habib, 1995;Nader, 2014), yet the Lebanese ranges have been further affected 492 by the passage of the LFS in the Late Miocene and Pliocene. The main folding 493 phase of the Palmyrides and the initial uplift of Mount Lebanon, took place 494 during the Late Oligocene or Early Miocene [START_REF] Brew | Tectonic 1135 and Geologic Evolution of Syria[END_REF][START_REF] Sawaf | Geologic 1404 evolution of the intraplate palmyride basin and euphrates fault system syria[END_REF]495 Chaimov et al., 1992;[START_REF] Beydoun | Evolution and development of the Levant (Dead Sea Rift) 1114 transform system: a historical-chronological review of a structural controversy[END_REF][START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]Ghalayini et al., 2017). 496 497

Stratigraphic setting 498 499

The documented units observed in outcrops range from the mid-Jurassic to the 500 Upper Cretaceous in Mount Lebanon, with Paleogene and Neogene sediments 501 closer to the shoreline and in the Bekaa valley. Pre-Jurassic units are not exposed 502 onshore. Nevertheless, correlation with the geology of the Syrian Palmyra basin 503 allowed suggesting that the Triassic sequence is expected to extend westward 504 and is thicker in Lebanon [START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]. This is based on extensive 505 deep exploration wells and seismic data in Syria [START_REF] Sawaf | Geologic 1404 evolution of the intraplate palmyride basin and euphrates fault system syria[END_REF]Chaimov et 506 al., 1993;[START_REF] Brew | Tectonic 1135 and Geologic Evolution of Syria[END_REF] as well as an old electro-resistivity survey that 507 indicated the presence of a conductive unit located at 650m below the oldest 508 outcropping Jurassic outcrop (Renouard, 1955) which was attributed to a 509 potential Triassic evaporate layer [START_REF] Beydoun | Petroleum Prospects of Lebanon: Reevaluation[END_REF][START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]. 510 Therefore, it is likely that the Triassic in Lebanon is analogous to Syria, which has 511 et al., 2014;[START_REF] Bou Daher | Geochemical 1124 and petrographic characterization of Campanian -Lower Maastrichtian 1125 calcareous petroleum source rocks of Hasbayya, South Lebanon[END_REF]. 570 571The overlying Paleocene units are 300 m thick and consist of chalky limestones 572 and marls. Nummulitic middle Eocene limestone have been documented in the 573 Bekaa [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF] where they reach up to 900 m in thickness (Hawie et al., 574 2014) and in south of Lebanon. The upper Eocene and Oligocene units are absent 575 in all of Lebanon due to uplift and erosion of the margin during the Early 576 Miocene compressive folding event [START_REF] Walley | Some outstanding issues in the geology of Lebanon and 1436 their importance in the tectonic evolution of the Levantine region[END_REF], except of one outcrop south 577 of Lebanon (Müller et al., 2010). The middle Miocene is outcropping and consists 578 of continental lacustrine facies in the Bekaa in contrast with the Miocene open 579 marine facies along the margin [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF][START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF]. The 580 Pliocene in this area is referred to as the Zahle formation (Nader et al., 2016) and 581 corresponds to clastic deposits, breccias, silt, marl and lacustrine limestone, 582 overlain by alluvial fan conglomerates [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF]. [START_REF] Brew | Tectonic 1135 and Geologic Evolution of Syria[END_REF], separated by a deep 588 crustal fault that forms the westward extension of the Jhar fault in the 589 Palmyrides (Ghalayini et al., 2017;[START_REF] Walley | Some outstanding issues in the geology of Lebanon and 1436 their importance in the tectonic evolution of the Levantine region[END_REF]. Northern Mount Lebanon 590 consists of a broad and symmetric box-fold anticline, (Renouard, 1955;Beydoun 591 and Habib, 1995), while southern Mount Lebanon is topographically lower and 592 the deformation zone includes several shorter wavelength folds including a tight 593 SE verging overfold termed the Niha-Barouk anticline [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF]Walley, 594 1998) bounds the eastern side of southern Mount Lebanon, while it cuts through its 605 northern counterpart. It is believed to be an ancient fault system from pre-606 Cambrian times [START_REF] Butler | The structural 1138 response to evolving plate kinematics during transpression: evolution of the 1139 Lebanese restraining bend of the Dead Sea Transform[END_REF]. The LFS effect in Lebanon is mostly 607 tranpsressive resulting in a restraining bend and causing large uplift of the 608 existing structures during the Pliocene. Since the late Quaternary, it is believed to 609

Page 25 of 78 For review only Journal of Petroleum Geology accommodate principally strike-slip movements [START_REF] Daëron | Constraints on the post ∼25-ka slip rate of the Yammoûneh fault 1161 (Lebanon) using in situ cosmogenic 36Cl dating of offset limestone-clast fans: 1162[END_REF]Gomez et 610 al., 2006). Transpression and strike-slip tectonics are mainly accommodated by 611 several faults including the Roum and Serghaya Faults. They are major sinistral 612 strike-slip faults branching from the southern LFS in the Golan Heights and 613 accommodate part of the displacement along the LFS (Gomez et al., 2001;Butler 614 et al., 1998). 615 616 Several ENE-WSW, currently active, dextral strike-slip faults are documented 617 along Mount Lebanon [START_REF] Gedeon | Structural analysis of latitudinal faults in the Mount Lebanon 1229 north of Beirut: their kinematic and their role in the tectonic evolution of 1230 Lebanon[END_REF] and extend to the Levant margin offshore 618 [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF] Geochemical analysis of gas samples from Middle Jurassic to Pliocene reservoirs 633 along the southeastern margin of the Levant Basin proved the presence of five 634 thermogenic and biogenic sources (Feinstein et al., 2002). Offshore Lebanon, the 635 Permian and Triassic thermogenic sources -if present -are believed to generate 636 petroleum between 90 and 34 Ma in the deep basin [START_REF] Bou Daher | 3D 1120 thermal history and maturity modelling of the Levant Basin and Margin[END_REF]. The 637 Upper Jurassic Kimmeridgian thermogenic source rocks have most probably 638 generated oil between the Late Cretaceous and the Late Miocene. The Upper 639 Cretaceous Campanian might constitute good thermogenic source rocks which 640 have produced hydrocarbons between 34 and 16 Ma. However, it is expected 641 that in the deep basin, the Campanian source rock quality and TOC content 642 would decline [START_REF] Bou Daher | Geochemical 1124 and petrographic characterization of Campanian -Lower Maastrichtian 1125 calcareous petroleum source rocks of Hasbayya, South Lebanon[END_REF]. Paleocene and Eocene thermogenic 643 source rocks have probably produced hydrocarbons during the Oligocene and 644 are still active in some parts of the basin. 645

646

The Oligocene unit might constitute potential thermogenic source rocks which 647 have started to generate hydrocarbons at around 6 Ma and are in the maturity 648 window at the present day. In addition, the Oligocene is believed to contain a 649 promising biogenic potential in the deep basin in which generation of biogenic 650 gas might have occurred between 18.5 and 6 Ma, while on the Lattakia Ridge and 651 in the more proximal basinal realm it might still be ongoing (Bou Daher et al., 652 2016) as the units are thinner and located at shallower intervals. In fact, the most 653 productive biogenic source rocks in the southern Levant are thought to be within 654 the Oligocene sequence [START_REF] Gardosh | Petroleum systems of Israel[END_REF] and these are 655 expected to extend northward to Lebanon [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF]Nader, 2014). 656

Other biogenic source rocks include the lower and middle Miocene from which 657 suggest that the these source rocks are rich in organic sulphur at high TOC (Bou 683 Daher et al., 2014;[START_REF] Bou Daher | Geochemical 1124 and petrographic characterization of Campanian -Lower Maastrichtian 1125 calcareous petroleum source rocks of Hasbayya, South Lebanon[END_REF] leading to hydrocarbon generation at 684 earlier stages of thermal maturity [START_REF] Bou Daher | 3D 1120 thermal history and maturity modelling of the Levant Basin and Margin[END_REF]. Large amounts of 685 immature solid bitumen are found in caves and along fault planes in the Bekaa 686 which are typical for early stages of hydrocarbon generation from type IIS 687 kerogen [START_REF] Bou Daher | Geochemical 1124 and petrographic characterization of Campanian -Lower Maastrichtian 1125 calcareous petroleum source rocks of Hasbayya, South Lebanon[END_REF]. 688

Reservoirs

690

The main reservoirs in the deep basin are found in the Oligo-Miocene unit and 691 consist of sand deposited in deep-water turbidite systems [START_REF] Gardosh | The Oligo-1205 Miocene deepwater system of the Levant Basin[END_REF]692 Hawie et al., 2013). In the lower Miocene unit, the Tamar sand is considered as 693 the best reservoir interval, consisting of sand with high net-to-gross and high 694 porosity/permeability in the range of 20-27% and 500-1000 md respectively 695 [START_REF] Gardosh | Petroleum systems of Israel[END_REF]. The fact that the Cenozoic unit in the deep 696 basin offshore Lebanon is much thicker than its southern counterpart may 697 suggest that the equivalent potential reservoirs might also be thicker. 698 Investigation of the normal fault system offshore Lebanon has revealed that the 699 growth of faults has been affected by mechanical stratigraphy caused by a strong 700 competent lower Miocene unit with faults nucleating in incompetent fine grained 701 sediments. The competent interval is interpreted to consist of a ~100m thick 702 sandy unit equivalent of the Tamar sand in the south [START_REF] Ghalayini | Growth of 1238 layer-bound normal faults under a regional anisotropic stress field[END_REF] [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF] point that the main reservoirs 708 are possibly located in the upper Miocene and suggest an increased sand content 709 at the base Oligocene. The fact that the normal faults have smaller heights and 710 displacement in this area point that there is a barrier to vertical fault 711 propagation [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]. As the faults do not propagate to the upper 712 Miocene and lower Oligocene units, it is likely that the latter units consist of 713 incompetent lithologies which might be attributed to coarse clastics or sand. The 714 provenance of clastic material in this area is most likely from a northerly source, 715 probably from the Lattakia region in Syria. In addition, the erosion of Cretaceous 716 to Miocene carbonate platforms contemporaneously with Mount Lebanon's 717 accelerated uplift in the Late Miocene/Pliocene, could lead to more 718 conglomeratic material from the northern Lebanese ranges [START_REF] Hawie | Multi-scale constraints of sediment 1292 source to sink systems in frontier basins: a forward stratigraphic modeling case 1293 Page 53 of 78 For review only[END_REF]719 Hawie et al., 2013). 720 721 Along the Levant margin, the Jurassic carbonate platform is far from meteoric 722 influence prevalent onshore (Nader and Swennen, 2004a). This fact, together 723 with the predicted presence of fracture-associated hydrothermal dolomites 724 could form effective reservoirs in the Jurassic carbonate platforms. The Lower 725

Cretaceous Chouf sandstones are correlated to the Rutbah formation in Syria, 726 which constitutes the principal reservoir in the Euphrates Graben (Barrier et al., 727 2014;[START_REF] Sawaf | Geologic 1404 evolution of the intraplate palmyride basin and euphrates fault system syria[END_REF], and to the Helez formation in the southern Levant, 728 which constitutes the reservoir for the Helez field [START_REF] Shenhav | Lower Cretaceous Sandstone Reservoirs[END_REF]. Therefore, 729 the Chouf sandstone might form good reservoirs in the margin offshore. Other 730 units in the Cretaceous, such as the Albian and the Aptian, could form good 731

Page 30 of 78 For review only Journal of Petroleum Geology reservoirs consisting of isolated reefal buildups similar to the Eratoshtenes 732 margin [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF][START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF][START_REF] Esestime | Zohr -A newborn carbonate 1182 play in the Levantine Basin, East-Mediterranean[END_REF]. 733

Younger reservoirs along the Levant margin consist of the lateral ends of the 734 Oligo-Miocene clastic units onlapping on the Mesozoic carbonate platforms. 735

These reservoirs are believed to be of good quality due to their proximity to the 736 Mount Lebanon sedimentary source than their deep basin's equivalent. Miocene 737 reefs are also documented on paleo-highs along the northern margin and could 738 provide good reservoirs [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF][START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. 739 740In the onshore domain below Mount Lebanon, the expected reservoirs are pre-741 Jurassic. All exposed units are subject to severe weathering and influx of 742 meteoric waters, strongly deteriorating the reservoir quality (Nader and 743 Swennen, 2004a). Good reservoirs could belong to the Permian to lower Triassic 744 Amanus sand formation consisting of shales interbedded with channel 745 sandstones and siltstone beds together with the lower to mid Triassic 746 Kurrachine unit consisting of dolomite and sandy intervals. These units are 747 important oil and gas reservoirs in the Palmyrides (Barrier et al., 2014) and in 748 the southern Levant's as they are equivalent to the Mihilla formation (Gardosh 749 and Tannenbaum, 2014). In the Bekaa region, the reservoirs are believed to be 750 unit point that the latter is likely constituted by shales (Kosi et al., 2012) and 761 highly overpressured rocks [START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. In the Oligo-Miocene unit, 762 intra-formational shale or clay may constitute good seals for Miocene reservoirs 763 similar to the Tamar and other fields in the south [START_REF] Gardosh | The Oligo-1205 Miocene deepwater system of the Levant Basin[END_REF]. In this 764 unit, the normal faults could either form good lateral seals at present day or act 765 as conduits to hydrocarbon migration. In fact, the maximum documented 766 displacement on these faults is around 350 m, causing a large offset of reservoir 767 against seal lithologies, increasing the likelihood of impermeability along fault 768 planes. In contrast, the same faults are observed to cross-cut the Tamar, 769

Aphrodite and Leviathan fields in the southern Levant basin but they do not 770 seem to affect the continuity of the reservoirs [START_REF] Gardosh | Petroleum systems of Israel[END_REF]. 771 Therefore, this juxtaposition relationship still needs to be checked during 772 drilling. The shallowest cap rocks in the basin are the Messinian salts forming up 773 to 1500 m of evaporites and are as such considered to be an optimal seal if 774 underlying reservoirs are present. 775

776

The cap-rocks in the Lattakia Ridge are the same as the ones in the deep basin. In 777 this area, the complex deformation and extensive fracturation has most probably 778 affected the sealing potential of all units. This effect is most pronounced at the 779 Lattakia ridge itself and diminishes south-eastward toward the deep basin. In 780

Page 32 of 78

For review only Journal of Petroleum Geology addition, the Messinian unit is absent on top of the ridge while thinning 781 considerably in the adjacent areas. Gas chimneys are frequently observed in the 782 area where the Messinian is absent and/or thinning on top of anticlines SE of the 783 Lattakia Ridge. In one particular example, gas accumulations in the shallow 784 upper Miocene reservoirs were possibly leaked out when the seal was thinning 785 and absent, as evidenced by the chimneys documented only in the absence of the 786 salt (fig. 12). 787 788Along the Levant margin, potential cap rocks are the Lower Triassic evaporites of 789 the Kurrachine formation that are probably extending to the offshore carbonate 790 platform. The Kimmeridgian volcanic formation might also constitute a good seal 791 for deeper reservoirs, even though this unit is not laterally homogenous 792 [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF] with expected facies change toward the basin. Cretaceous 793 clays, marls, and basalts could represent good cap rocks for the underlying 794 reservoirs. The Messinian unit in the Levant margin is either considerably 795 thinning in some locations (fig. 3) or is absent in others (fig. 5) which could 796 diminish the Messinian seal quality in this location. 797 798 Onshore, the expected thick Upper Triassic evaporites of the Kurrachine 799 Formation seal the underlying dolomitic reservoirs and protect them from 800 meteoric influence since the uplift of Mount Lebanon (Nader, 2011).They are 801 well documented to provide a regional seal in the Palmyrides (Barrier et al., 802 2014;[START_REF] Sawaf | Geologic 1404 evolution of the intraplate palmyride basin and euphrates fault system syria[END_REF] and in the southern Levant with the equivalent 803 Saharonim and Mihilla Formations [START_REF] Gardosh | Petroleum systems of Israel[END_REF]. In the 804 Bekaa, intra-formational volcanic, marly and shaly units of Jurassic and 805 Lebanon is proposed. In the southern margin, the seismic horizons were tied to 863 nearby well which resulted in updated stratigraphic subdivisions of the Saida-864 Tyr plateau. The Triassic unit is likely present based on the predicted unit 865 thicknesses in Lebanon [START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]. This is conformable with the 866 finding of Nader et al. (2016) onshore in which they suggest the presence of high 867 amplitude seismic horizons which they interpret as the Top Triassic based on 868 regional thicknesses. The high impedance contrasts along this horizon in the 869 southern margin could be related to the presence of evaporites within the 870 Triassic but this still needs to be checked by drilling. 871 872 Recently, the discovery of Zohr in carbonate reservoirs around the Eratosthenes 873 seamount has opened new play concepts in the basin and attracted attention to 874 the carbonate potential (e.g. [START_REF] Esestime | Zohr -A newborn carbonate 1182 play in the Levantine Basin, East-Mediterranean[END_REF][START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF] Lebanon (Nader and Swennen, 2004a;Nader and Swennen, 879 2004b) and Syria (Barrier et al., 2014). As they are sealed from meteoric 880 invasion, they are very likely not affected by flushing and so are good reservoirs 881 (e.g. Nader and Swennen 2004a). [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF] demonstrate the presence 882 of reefal buildups onshore Lebanon based on extensive field observations and 883 analysis and suggest the likely continuity of such buildups to the margin 884 offshore. This could make the potential reservoir within the Levant carbonate 885 sequence equivalent to the Eratosthenes ones and therefore provide effective 886 analogues for the Zohr (e.g. [START_REF] Esestime | Zohr -A newborn carbonate 1182 play in the Levantine Basin, East-Mediterranean[END_REF]). An attractive aspect of the 887 Levant margin is the strong thermogenic potential in this domain which could 888 invoke liquid hydrocarbon accumulations. 889 890 This new interpretation of the margin reduces risk in exploration as it provides 891 new elements for the petroleum system and hence new potential prospects. The 892 Lower Cretaceous sandstone is identified in the northern margin, 893 stratigraphically trapped between the Jurassic and Cretaceous carbonate talus. 894

This unit offshore appears to be thicker than its equivalent onshore (e.g. 895 [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF][START_REF] Bellos | Sedimentology and diagenesis of some neocomian-1099 Barremian rocks (Chouf Formation) southern Lebanon[END_REF]. This could be related to an established 896 basin/margin differentiation since at least the Early Cretaceous in which a larger 897 accommodation space is available for the Nubian sand to be deposited offshore. 898 [START_REF] Hawie | Tectono-stratigraphic evolution of the 1281 northern Levant Basin (offshore Lebanon)[END_REF] indeed argues for a general westward facies variation in 899 Mesozoic sequences caused by a transition to deeper basinal environments. 900

901

The relatively good reservoir properties of the Lower Cretaceous sandstone unit 902 onshore Lebanon and Syria (e.g. [START_REF] Bellos | Sedimentology and diagenesis of some neocomian-1099 Barremian rocks (Chouf Formation) southern Lebanon[END_REF] and the hydrocarbon production 903

Page 37 of 78 For review only Journal of Petroleum Geology from this same unit in the southern Levant [START_REF] Shenhav | Lower Cretaceous Sandstone Reservoirs[END_REF]Gardosh and 904 Tannenbaum, 2014), suggest that similar prospective plays might well exist 905 offshore Lebanon. In fact, DHI's such as bright spots and a potential flat-spot is 906 observed in seismic data (fig. 13) which invoke hydrocarbon accumulations, 907 originating from thermogenic source rocks. This unit extends along the entire 908 margin offshore Lebanon and therefore could be associated to large prospects. 909

The challenge, however, is the depth of this play being around 8 km in some 910 locations, resulting in potentially high pressure reservoirs. 911 912 Additional DHI's, such as flat spots, can also be observed within the Oligocene 913 unit along the Levant margin (fig. 14). With the relatively better reservoir quality 914 expected in this location [START_REF] Hawie | Multi-scale constraints of sediment 1292 source to sink systems in frontier basins: a forward stratigraphic modeling case 1293 Page 53 of 78 For review only[END_REF], it is very likely that Oligo-Miocene 915 pinchout prospects could also be promising. As the flat spot is located below the 916 Base Miocene horizon, this indicates that the seal might be around the Base 917 Miocene. This could point that towards the margin, the base Miocene is probably 918 be associated with shaly/marly or fine grained facies and transitions to coarser 919 grains or sandy facies toward the basin. 920 domain termed the 'offshore' in which a similar petroleum system is expected 939 (Nader and Swennen, 2004b). More detailed analysis, however, suggests 940 otherwise. The source rocks charging the reservoirs in the Lattakia Ridge are 941 supposed to be both thermogenic and biogenic, while in the deep basin the 942 biogenic ones are dominant [START_REF] Bou Daher | 3D 1120 thermal history and maturity modelling of the Levant Basin and Margin[END_REF]. In addition, the traps are of 943 Late Cretaceous age and the reservoirs intervals are unlikely to consist of the 944 Tamar sands but could belong to other intervals [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]Ghalayini 945 et al., 2016;[START_REF] Hawie | Multi-scale constraints of sediment 1292 source to sink systems in frontier basins: a forward stratigraphic modeling case 1293 Page 53 of 78 For review only[END_REF]. Such geological variations necessitate to 946 associate the Lattakia Ridge to an independent domain of the deep basin. 947 948 The onshore domain have been discussed abundantly and the expected 949 petroleum system is well described from regional correlations and field studies 950 (e.g. [START_REF] Beydoun | Petroleum Prospects of Lebanon: Reevaluation[END_REF][START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]Nader and Swennen, 2004b;951 Nader, 2014;[START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. Although the expected source-reservoir 952

Significance of geological domains

Page 39 of 78 For review only Journal of Petroleum Geology configurations differ between the Bekaa valley and Mount Lebanon, they have 953 been grouped into one domain. They both are believed to contain a good 954 thermogenic system [START_REF] Bou Daher | 3D 1120 thermal history and maturity modelling of the Levant Basin and Margin[END_REF] in which the Triassic petroleum 955 system is dominant. In the Bekaa, a working Cretaceous petroleum system might 956 also be effective beneath the quaternary cover (e.g. Nader, 2014;Beydoun, 957 1977). 958 959 Four petroleum system charts have been compiled for the Lattakia, deep basin, 960 margin and onshore domains (figs. [15][16]. They show the variable petroleum 961 system elements expected in each. The reservoirs, seals, traps and source rock 962 maturity have been discussed in previous sections and are summarized in each 963 chart. In the Lattakia ridge domain and the Levant margin, a mixed 964 thermogenic/biogenic charge is feeding the reservoirs as of the Late Cretaceous 965 to modern time, while in the deep basin a dominantly biogenic system is 966 expected. Onshore, only thermogenic sources are active and charging the 967 reservoirs as of the late Tertiary. 968 The anticlines offshore Beirut (fig. 9) are interpreted to have thin-skinned 979 deformation in which the Eocene unconformity horizon acts as a detachment 980 surface [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]Kosi et al., 2012). In the southern Palmyrides, the 981 Triassic salt sequence acts as an effective detachment surface for some of the 982 anticlines in Syria [START_REF] Brew | Tectonic 1135 and Geologic Evolution of Syria[END_REF]. One particular example is the Cheriffe 983 anticline [START_REF] Chaimov | 1150 Mesozoic and Cenozoic deformation inferred from seismic stratigraphy in the 1151 southwestern intracontinental Palmyride fold-thrust belt, Syria[END_REF] which shows a similar structural style to the 984 offshore Lebanese ones. In addition, some of the anticlines in the Palmyrides 985 have a box-fold geometry, based on subsurface data and surface expression 986 [START_REF] Searle | Structure of the intraplate eastern Palmyride fold belt, Syria[END_REF] drawing analogies to the Qartaba anticline onshore. The latter has 987 very steep to overturned flanks locally with a gently westward dipping top. This 988 suggests that the Qartaba anticline is not simply a horst as it was commonly 989 referred to [START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF] the Levant margin (Ghalayini et al., 2017). This increases the structural 1002 similarities of these anticlines and insinuates a similar timing, being in the Late 1003 Miocene prior to the effect of the strike-slip faults (e.g. [START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]. 1004 1005The exploration implications on the structural style of the anticlines is profound 1006 as it affects the subsurface closures and location of faults. The uncertainties are 1007 probably less offshore with the availability of 3D seismic data, but the challenges 1008 persist for onshore anticlines. The adopted structural style helps predicting the 1009 likely location of subsurface traps and directly affects the proper positioning of 1010 the wells during exploration. Therefore, using analogues to help exploration 1011 offshore and onshore Lebanon could be of a great value and would reduce 1012 In the onshore domain, exploration wells have been drilled with total depths 1017 ranging from 1,421 m to 3,065 m [START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]. The deepest 1018 formations reached range in age from Late Cretaceous to mid-Jurassic. In most of 1019 these wells, the main reservoirs were water-flushed due to erosion leading to 1020 bad and ineffective seals, direct communication with elevated meteoric recharge 1021 areas in the high Lebanon and Anti-Lebanon Mountains, or their proximity to 1022 major faults (Nader and Swennen, 2004a;[START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]. Therefore, 1023 it is clear that prospective units must be pre-Jurassic with petroleum system 1024

Regional

  Interpretation of three seismic lines along the margin offshore north and south 146Lebanon were performed (figs 3 to 6). The data used consist of pre-stack depth 147 migrated 3D seismic cube acquired in 2012 by PGS. Streamer length was 7050m 148 long at a spacing of 12.5m and 25m shot point intervals. The interpretation was 149 performed on depth-converted sections. Because no well data were available, 150 time to depth conversion was done using a velocity model built from stacking identified in seismic data based on impedance contrast 156

  quiescence and gentle subsidence of the Levant region starting the mid to late 195 Jurassic. The seismic package between RN2 and RN3 likely represents the 196 Jurassic unit composed of shallow-water, inner to middle shelf carbonates. Its 197 thickness of 1 -1.5 km is in coherence with the thickness of the Jurassic in north 198

  . Therefore, RN3 could refer to 200 the Late Jurassic-Early Cretaceous sequence boundary. The seismic facies 201 transition from continuous to chaotic reflectors indicate mass transport or talus 202 deposits originating from the Jurassic carbonate platform and deposited at the 203 distal end of the margin over a slope. The abrupt facies variation into high 204 amplitude bright reflectors toward the distal basin could point to the presence of 205 Jurassic clastic units away from the margin. 206 207 The unit between RN3 and RN4 exhibit a set of stacked high amplitude reflectors 208 indicating different facies than the adjacent carbonates. They are likely 209 representing thick bedding which alludes to sand packages of a possibly Lower 210 Cretaceous age. Therefore, this unit could be analogous to the onshore 211 Hauterivian Chouf formation, and RN4 could likely represent the top 212

  amplitude set of reflectors, with occasional dimming. Horizon RS8 marks the 244 boundary between stacked high amplitude bright reflectors to the east, and 245 stacked continuous medium to high amplitude reflectors to the west. The latter 246 package is pinching out and exhibits onlap on RS8. Horizons RS9 to RS13 are 247 picked up based on the interpretation of[START_REF] Hawie | Sedimentologic and stratigraphic evolution of northern Lebanon since the Late 1287 Cretaceous: implications on the Levant margin and basin[END_REF]. 248 249 The seismic units between horizon RS2 and RS3, and horizons RS4 and RS5 are 250 thinning to the west and disappear. Their seismic facies change abruptly from 251 stacked bright horizons to chaotic. On top of horizon RS2, pinnacle shape 252 buildups are observed. They cover an area of about 200 Km 2 . 253 254 Large vertical displacement related to vertical faults is observed north and west 255 of the plateau. The northern bounding fault displaces RS8 horizon 2 km upward 256 and locally forms a mini-basin along RS12 (fig. 5). The faults to the west have 257 positive-flower geometries with two anticlines observed along their strike (fig. 258 6). ENE-WSW to ESE-WNW normal faults are observed at the easternmost STP 259 (fig. 5) having a displacement of few hundred meters and extend between RS1 260 and RS8 horizons. Their strike is ENE-WSW to ESE-WSW. well data, horizons RS3 to RS7 correspond to Top Jurassic, 265 Top Hauterivian, Top Aptian, Top Albian and Top Cennomanian. As RS8 horizon 266 is truncating the Turonian and Senonian units as well as deeper units to the west, 267

  in 280 which horizons RS9 to RS13 correspond to the Eocene Unconformity, Base 281 Miocene, Base mid Miocene, Base Messinian and Base Pliocene respectively. 282 These units are overlying the Mesozoic units found eastward and are onlapping 283 on the Senonian Unconformity horizon, while to east and closer to the shoreline, 284 the Mesozoic is directly overlain by the Pliocene and the Messinian unit is not 285 observed in seismic data. This likely indicates an existing topographic high prior 286 to the deposition of the Tertiary unit. The westward seismic facies variation 287 observed in the Jurassic and Cretaceous units could be interpreted as talus 288 deposits originating from the carbonate platform in the East. Overlying the RS2 289 horizon, the pinnacle shape geometries could consist of local build-ups or 290 isolated carbonate mounds, though it is challenging to assess their true nature 291 from seismic data alone.

  domains and are as such a review of the available literature. The lithostragraphic 322 column of the Levant region summarizes the stratigraphy, structures and 323 expected petroleum systems (fig. 8on an attenuated crust (Inati et al., 2016) during the Triassic and 328 Jurassic when the Neo-Tethys has opened up following the rifting of Pangea. It is 329 characterised by a thick Cenozoic sedimentary cover reaching over 8 km 330 thickness, overlying a Mesozoic succession

Page

  is a prominent structure that is found at the NW part of the 411 Levant basin offshore Lebanon. It is part of the Cyprus Arc system and stretches 412 from the Syrian region in the NE to offshore southern Cyprus. It is characterized 413 by a strong topographic high observed at the seafloor. 414 this domain is similar to the rest of the Levant basin, albeit 418 with different thicknesses of units, especially to the west of the ridge itself. The 419 same horizons in the deep basin are also documented along the Lattakia Ridge. 420

Page

  consists of a series of south-east verging thrusts forming 433 prominent NE trending narrow structures and having a profound bathymetric 434 expression (fig. 11). Several anticlines are found adjacent to the Lattakia ridge. 435 These are symmetrical NE-trending structures, which in the Oligo-Miocene units 436 appear very similar to compressional anticlines, while in the deeper Eocene and 437 Mesozoic unit they consist of deep-seated SE verging thrusts with steep SE limbs 438 (fig. 11). Back thrusts are documented along this ridge and are believed to have 439

  domain covers the area adjacent to the Lebanese shoreline 446 and comprises the Saida-Tyr plateau, a small narrow strip in front of Beirut, and 447 a larger platform north of Lebanon (fig. 7). It is differentiated from the Cenozoic 448 deeper basin by its thick Mesozoic carbonate succession on top of which the 449 Cenozoic units are pinching out and onlapping. It is generally acknowledged that 450 the Levant margin encompasses the onshore domain in Lebanon, including 451 Mount Lebanon (Nader 2011). However, for the purpose of this paper, we 452 differentiate the Levant margin from the inner onshore domain (i.e. Mount 453

Page

  domain comprises the prominent Lebanese ranges including Mount 485 Lebanon, Anti-Lebanon and the Bekaa Valley in between (fig. 1). It is located at 486

Page

  also been proposed based on interpretation of reflection seismic data onshore 512 northernLebanon (Nader et al., 2016). The Triassic unit in the Palmyrides is 513 documented to consist of a Lower Triassic Amanus shale formation and a middle 514 to Upper Triassic Kurrachine formation. The latter is subdivided into two units, a 515 dolomite and an overlying anhydrite sequence. Equivalent units are identified in 516Jordan(Luning and Kuss, 2014) and in the southern Levant margin(Gardosh and 517 Tannenbaum, 2014). 518519The Jurassic sequence in Lebanon is approximately 1,700 m thick, and could 520 reach 2,700 m thick in the Mount Hermon region of the southern Anti-Lebanon 521 ranges[START_REF] Dubertret | Carte géologique du Liban au 1/200000 avec notice 1178 explicative: Beirut, République Libanaise[END_REF]. The Lower Jurassic consists of a dark and thick 522 dolomite sequence termed the Chouane Dolomites. It is overlain by the mid to 523 late Jurassic Kesrouane Limestone Formation deposited during a period of post-524 rift subsidence in shallow water environment. Above the Kesrouane formation, 525 lies the Kimmeridgian Bhannes volcanic unit which consists of a mixture of 526 carbonates, marls, lavas and pyroclastics. It is distinctive in some location by its 527 red soils and hard basalts, with occasional pillow lavas. The thickness of this unit 528 decreases southward and is in average around 80-100m thick. Overlying the 529 Bhannes volcanics, is a 60-80 m thick cliff-forming formation termed the Bikfaya 530 formation. It consists of massive bedded limestone deposited in a period of sea 531 level rise. The end of the Jurassic is marked by a return to shallow water 532 sedimentation with deposition of ferruginous oolitic limestone of the Salima The Cretaceous sedimentary cycle starts with deposition of the Hauterivian 536 Chouf sandstone formation (Maksoud et al., 2014; Walley, 1997). This unit is 537 between 5-300 m thick across Lebanon and thins northward reflecting possible 538 clastic provenance from the southeast. It consists of ferruginous brown to white 539 sandstone with clays, coaly shales and volcanics. It was deposited under a fluvial 540 to deltaic littoral environment. The overlying Barremian Abieh formation varies 541 between fossiliferous limestone, marls and sandstones and represents a 542 transition between the fluvial Chouf and the overlying shallow marine late 543 Barremian to Aptian units. The latter is a conspicuous cliff-forming formation 544 clearly visible throughout all of Lebanon, with a thickness of about 50 m 545 (Maksoud et al., 2014). It consists of a single massive grey limestone. Small scale 546 rudist and stromatoporoidal reef buildups are visible in some locations. It 547 represents a sequence of shallow marine transgressive carbonate facies linked to 548 early Aptian eustatic rise. The overlying Albian corresponds to thin bedded 549 carbonates, marls and terrigenous sand. It represents a brief return to 550 terrigenous clastic deposition, in a general marine setting, before sea levels 551 caused renewed carbonate deposition. 552 553 The upper part of the Cretaceous and early Paleogene is almost entirely 554 composed of carbonate. The Cennomanian Sannine formation is 600 m thick and 555 consists of medium to thick bedded shallow water limestones and marly 556 limestone. This sequence thickens to the west with increasing thin bedded chalk 557 and cherty pelagic sediments along the coast. It is possible that these lateral 558 facies change and thickness increase could point to a shift from shallow water 559 deposition in the east, to deeper environments westward dominated by 560 carbonate turbidite deposits (Hawie et al., 2014). The overlying Turonian unit is 561 200-300 m thick and represents a continuation of the carbonate deposition of 562 the Cennomanian and is characterized by thin finely bedded, chalky micrites and 563 cherts with abundance of Hippurite fossils. The Senonian/Campanian-564 Maastrichtian Chekka formation consists of very dark grey to white sequence of 565 chalks and marly limestone units. Its thickness ranges from 100 to 500 m with 566 the thickest succession documented in the southern Bekaa valley and is made of 567 chalk and marly limestone. It has a very good source rock potential as it contains 568 organic rich argillaceous limestone with TOC values between 2 and 10% (Bou 569 Daher

  a NNE trending structure. It exhibits two different structural 587 styles, similar to the Palmyrides ranges

  . Anti-Lebanon is an anticlinal structure very similar to Mount Lebanon 595 located more inland and merges topographically with the Syrian Palmyrides 596 ranges in the south. The Bekaa valley, which is dominated by a thick Tertiary to 597 recent continental succession, separates the two mountain ranges. The valley is 598 narrow in the south in the Hasbaya area and widens northward into the Homs 599 Plain in Syria. 600 601 The Yammouneh Fault passes through Mount Lebanon and forms a continuation 602 of the plate boundary between Arabia and Africa that stretches from Aqaba in 603 the south to Taurus in the North. In Lebanon, it reaches 160 km length and 604

  . These faults have most likely nucleated during the 619 Mesozoic as normal faults during the breakup of Pangaea and were subsequently 620 reactivated during the Neogene compression(Collin et al. 2010; Ghalayini et al. 621 2014). Similar faults are also found in the Palmyra basin further east. are thought to exist in units between the Permian to 626 Pliocene based on regional stratigraphic correlation, field investigations and 627 geochemical analysis. The major potential source rocks are described here

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  methane is believed to have been expelled during the Messinian and is currently 658 ongoing[START_REF] Bou Daher | 3D 1120 thermal history and maturity modelling of the Levant Basin and Margin[END_REF]. Based on thermal history modelling, BouDaher 659 et al (2016) predicted that a thickness of 700 to 1500m of sub-Messinian 660 Miocene succession is within the biogenic zone at present day. Detailed 661 information on source rock kinetics, maps of source rock maturation and 662 transformation ratios are presented in Bou Daher et al. source rocks -if present -would have generated 667 hydrocarbon between 75 Ma to present day along the margin and onshore(Bou 668 Daher et al., 2016). In Syria, the upper Permian/Lower Triassic Amanus 669 dolomites are very good source rocks for Triassic Reservoirs in the Palmyrides 670(Barrier et al., 2014) and might therefore be as good in the Levant margin and 671 onshore. Similarly, the Upper Jurassic Kimmeridgian source rocks most probably 672 generated oil between the Oligocene to the present day along the margin(Bou 673 Daher et al., 2016) with minor amount on the onshore in the Late Miocene which 674 were most probably washed out by meteoric waters(Nader and Swennen, 675 2004a). However, in the deeply buried Jurassic under the Bekaa Valley, the 676 Kimmeridgian source rocks are in the oil window today. 677678The Campanian source rocks appears not to have been buried deep enough in 679 Mount Lebanon to generate hydrocarbon. In the Bekaa valley and along the 680 margin, however, the Campanian is in the maturity window and minor 681 generation might have occurred[START_REF] Bou Daher | Geochemical 1124 and petrographic characterization of Campanian -Lower Maastrichtian 1125 calcareous petroleum source rocks of Hasbayya, South Lebanon[END_REF]. Geochemical data 682

  In the deep basin, the Paleocene/Eocene package is believed to form a strong 756 impermeable unit sealing the deeper reservoirs and preventing vertical 757 hydrocarbon migration from deeper intervals. The consistent detachment of 758 normal faults on the Eocene unconformity horizon (fig.10) together with the 759 chaotic seismic facies and weak amplitudes observed in the Paleocene/Eocene 760

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  the deep basin offshore Lebanon is mostly related to structural and folded immediately prior to, or at the onset of the Messinian salinity crisis; 815 (2) NE trending transpressive anticlines and positive flower structures found 816 primarily in the south west of the STP and formed during the Late Miocene and 817 (3) Oligo-Miocene tilted fault blocks that nucleated during the lower Miocene 818 and active during Miocene time. Migration of hydrocarbon from biogenic source 819 rocks may have been aided by the intense faulting and fracturing of the Oligo-820 Miocene unit. As discussed earlier, the faults may constitute a good seal at 821 present day and provide 3-way closures. Their nucleation time during the early 822 Miocene and their continuous activity throughout the Miocene time (Ghalayini et 823 al., 2016) make these faults permeable throughout the Miocene. Therefore, any 824 petroleum migration after the Oligocene could result in charging the reservoirs 825 in the Oligo-Miocene unit. 826 827 In the Lattakia Ridge domain, the trap type is mostly structural with symmetrical 828 anticlines in the Cenozoic unit underlain by deep-seated SE verging thrust faults, 829 providing excellent four-way closures. These anticlines are found surrounding 830 the Lattakia Ridge as of the Late Cretaceous time, but the ridge itself is a poor 831 trap due to the lack of closure as a result of intense uplift and erosion of the 832 Cenozoic units. Migration of hydrocarbons from source to reservoirs must have 833 happened through the numerous faults and fractures associated with the intense 834 deformation of the Lattakia ridge since the Late Cretaceous times. Deformation 835 continued till modern day indicating that several faults are still active and 836 implying that they could form effective migration pathways. 837 838 Along the Levant Margin, trap mechanism is mostly stratigraphic within the 839 Mesozoic carbonate platform. Other stratigraphic traps include pinchout of the 840 Early Cretaceous sand sealed by Cretaceous carbonates in addition to pinchout of 841 Oligo-Miocene sandy units onto shallower Mesozoic strata and sealed by intra-842 Miocene shale. Structural traps include inversion structures, such as reactivated 843 ENE-WSW strike-slip faults (e.g. Ghalayini et al. 2014) forming 4-way dip 844 closures below the Messinian. Along the margin, pre-existing and inverted faults 845 may have played an important role in hydrocarbon migration from the deep 846 Mesozoic source rocks to shallower reservoirs. As these faults were active 847 throughout much of the geological time, they might have been permeable during 848 the Mesozoic and Cenozoic times. 849 850 Onshore, the traps are mostly of structural type, consisting of 4-way dip closure 851anticlines formed by the transpression along the LFS(Nader, 2014; Nader et al., 852 2016). Potential large traps are the Qartaba anticline(Nader, 2014; Nader, 2011) 853 together with other large structures, such as the Sir-Ed-Denie, Barouk-Niha and 854 seismic data, a new interpretation of the Levant margin offshore 862

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  . The 875 presented interpretation along the margin refines our understanding of the 876 expected carbonate sequences which could open up new play concepts. The 877

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  at updating the general knowledge on the potential 923 petroleum systems of Lebanon ahead to the first Lebanese offshore licensing 924 round. Based on a comprehensive review of previously published and achieved 925 integrated research work (geodynamics, stratigraphy, structural geology and 926 geochemistry) together with the interpretation of two key seismic profiles, we 927 more adequate when assessing the petroleum potential of 931 Lebanon as every domain is characterized by a variable petroleum system. This 932 is due to different geological characteristics of each domain resulting in different 933 source-reservoir-trap configurations, and hence different petroleum plays. 934 Therefore, this subdivision becomes very beneficial during exploration as it 935 focuses attention to specific plays which are a unique to each domain. 936 937 Previous studies have grouped the Lattakia Ridge and the deep basin into one 938

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  and facies documented both offshore and 971 onshore Lebanon draws similarities between the structural style and reservoirs 972 of nearby discoveries and therefore decreases uncertainty. Numerous analogue 973 studies are expected to be carried out in the Levant region in order to bring 974 further knowledge on such an under-drilled and less known basin. Here, we 975

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  but a compressional structure with possible fault-990 propagation folding and/or detachment faulting in which the middle Triassic 991 evaporates could have acted as a decoupling horizon. In fact, Nader et al. (2016) 992 identified in 2D seismic profiles a deepest horizon in north Lebanon possibly 993 representing the Triassic evaporites and suggested a continuity of the Qartaba 994 structure at depth. 995 996 Although the effect of the Triassic detachment layer is not observed offshore, the 997 Eocene unconformity could possess a similar decoupling effect. Therefore, the 998 thin-skinned anticlines of the Palmyrides are very likely structural analogues for 999 the offshore anticlines. In addition, both the offshore and Qartaba anticlines are 1000 by the same ENE trending dextral strike-slip faults documented along 1001

•••Figures 1448 1449Fig1:

 1448 Figures

Fig. 3 : 1461 Fig. 4 :Page 1474 Fig. 6 :

 31461414746 Fig. 3: Geo-seismic line showing the Levant margin off the coast of northern Lebanon

Fig 7 : 1481 Fig. 8 : 1484 Fig. 9 : 1489 Fig 10 :PageFig. 13 :

 7148181484914891013 Fig 7: The geological domains of Lebanon together with the nearby hydrocarbon

Fig. 15 :Fig. 16 :

 1516 Fig. 15: Petroleum system charts for the deep basin and Latakia Ridge domains.

Page 14 of 78 For review only Journal of Petroleum Geology

	343	contacts with their lower and upper bounding surfaces, stratal terminations and
	348	overall seismic facies. As the pre-Tertiary units in the deep basin were not drilled and are laterally continuous throughout the Levant basin.
	349
	350	A mixed carbonate-siliciclastic system characterizes the stratigraphy of the deep
	351	basin. The documented units consist of Mesozoic rocks, possibly deep-water
	352	carbonates or clastics, below the Senonian unconformity. The overlying Cenozoic
	353	consists of several units starting with the undercompacted shales of Paleogene
		age
	338	. They are believed to
	339	correspond to the Mid Jurassic, Jurassic-Cretaceous boundary, Senonian
	340	unconformity, Eocene unconformity, Base Miocene, Base mid Miocene, Base

Page 16 of 78 For review only Journal of Petroleum Geology

  . It 389 is not clear if the anticlines offshore Lebanon are overlying deeper reactivated 390

  on 469 the strike-slip faults, and those of Homberg et al. (2009) regarding the normal 470 faults in southern Lebanon. From south to north, the structural setting of the 471 Levant margin offshore Lebanon is markedly different. At the latitude of Beirut, a 472 narrow strip is documented in which the Mesozoic carbonate platform is 473 considerably narrow or absent. It is correlated with very steeply dipping 474

Page 29 of 78 For review only Journal of Petroleum Geology seismic facies interpretation

	703	or
	704	could correspond to another lithology that is mechanically more resistant to
	705	faulting.
	706

compartments. It has been suggested that both the Saida and the Damour faults

margin, the Lebanese onshore/offshore area is differentiated into four geological

domains, having distinct sedimentological and structural features: (1) the distal,

deeper basin, (2) The Lattakia Ridge, (3) the Levant Margin and (3) the onshore

(fig.7). The following sub-sections describe the main geological features of these

elsewhere in the Levant basin, it is very challenging to separate and seismically

characterize the Mesozoic strata in this domain. The Cenozoic units, such as the

Eocene, Oligocene-Miocene, Messinian and Pliocene, possess higher certainty

processes in sub-salt units. The structural traps consist of (1) NE trending

anticlines in the Oligo-Miocene, detaching on the Eocene unconformity horizon

Qartaba anticline, and could be potential prospects[START_REF] Beydoun | Lebanon revisited: new insights into 1111 Triassic hyrocarbon prospects[END_REF]

[START_REF] Beydoun | Petroleum Prospects of Lebanon: Reevaluation[END_REF]. They might have formed in the Late Miocene in association with

the activity of the LFS. In the Bekaa valley, potential traps might be structures

located beneath the quaternary cover (e.g.Nader et al., 2016).

Plateau[START_REF] Ghalayini | Impact of Cenozoic strike-slip tectonics on the evolution of the northern 1234 Levant Basin (offshore Lebanon)[END_REF]. The seismic data was tied to the nearby Adloun well

FIg. 12: gas chimneys on top of a Miocene anticline observed only when the

Messinian seal thins or is absent. The overlying Pliocene exhibits numerous bright

Acknowledgements 1084 1085 The authors are grateful to the Lebanese Petroleum Administration and the 1086 Ministry of Energy and Water of the Republic of Lebanon for allowing to publish 1087 the seismic lines in this manuscript and their interpretation. Petroleum Geo-1088 services (PGS) are thanked for their support and fruitful discussions. Editor Chris 1089 Tiratsoo and reviewers […] are thanked for their constructive reviews and 1090 comments, which enhanced the quality of this manuscript 1091

For review only Journal of Petroleum Geology For review only Journal of Petroleum Geology For review only Journal of Petroleum Geology For review only Journal of Petroleum Geology gas chimneys on top of a Miocene anticline observed only when the Messinian seal thins or is absent. The overlying Pliocene exhibits numerous bright spots and DHI's pointing to entrapment of the leaked gas into Pliocene reservoirs in structural closures. Page 74 of 78 For review only Journal of Petroleum Geology For review only Journal of Petroleum Geology For review only Journal of Petroleum Geology For review only Journal of Petroleum Geology