Ferry, Serge

Grosheny, Danièle

Merran, Yann

Mroueh, Moustapha

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The Cretaceous of Lebanon in the Middle East (Levant) context

International audienceThe Cretaceous succession of Lebanon was first described and dated mainly by Dubertret & Vautrin (1937), Dubertret (1955), and Saint-Marc (1974), supplemented by the later contributions of Smirnova & Mroueh (1980) for the Chouf Sandstones, Noujaim-Clark & Boudagher-Fadel (2001, 2002) for the Salima Formation. After two years of field work using facies sedimentology and sequence stratigraphy, and as part of the Middle East Basins Evolution (MEBE) Programme, we propose to divide the Cretaceous of Lebanon into three parts (Fig. 1): (a) Valanginian to upper Aptian, (b) upper Albian to Turonian, and (c) Post-Turonian to Eocene. The first period is represented by several depositional sequences each bounded by emersion surfaces (D1 to D3, Fig. 1). The top of the Jezzine Fm. is unique because it is an emersion (karstified) surface in northern Lebanon but appears to be only a simple transgression surface in the South. During these emergences the coastal sedimentary prism was shifted into the present-day offshore. The transgressions that initiate all three sequences, including that of the upper Albian, which is coincident with the beginning of period 2, starts with the deposition of volcaniclastics that may continue into the overlying, deepening-up, shallow-water marine deposits. This relationship suggests that these depositional sequences were tectonically-controlled, that is the transgressions were initiated by the renewal of an extensional regime accompanied by volcanism. As a result of the strong lowering of base level, most emersions are associated with incised valleys, particularly spectacular in Northern Lebanon. The strongest is at the base of the upper Albian sequence (Fig. 2). It corresponds to an emergence that lasted throughout the whole lower to middle Albian interval. The second period corresponds to the emplacement of a large system of carbonate platforms that covered much more of the Arabian craton. Changes of relative sea-level created a number of depositional sequences (not shown on Fig. 1) but drops in base level were not as great as those that occurred during the first period, except perhaps for the sequence ending near the Albian-Cenomanian boundary where an emersion surface of this age has been seen in the Anti-Lebanon and even in sections west of the Levant fault. These mild oscillations in relative sea-level are responsible of the spectacular sandwich of shallow-water (often rudist-bearing) carbonate facies alternating with finely-bedded or even laminated mudstones of Mount Lebanon. The Cenomanian-Turonian boundary, situated at the very base of the Ghazir Fm., is here coincident with the beginning of a deepening trend that peaks in the lower Turonian. The third period corresponds to an acceleration of the drowning of the Arabian craton, probably as a response to the beginning of the collisional trend responsible for the closing of the Tethys. On the Levant platform, deposition of micritic limestones and chalks began and continued into Eocene times. Several paleogeographic maps have been drawn that take into account our results in Lebanon and also include, tentatively, published data from adjacent countries. The task is not easy mainly because of the many remaining uncertainties about the age of Lower Cretaceous sandstones in Israel, Syria and Jordan. Two of them are presented (Fig. 3). The (?) Berriasian – Valanginian sequence is preserved only in some half-grabens in northern Lebanon under the "transgressive" Barremian Chouf sandstones. The term "transgressive" should be considered in terms of accomodation space because the facies is fluvial at its base, and becomes deltaic to marginal marine only at its summit. These sandstones were deposited most abundantly in a W-E oriented saddle west of the Levant fault. East of the fault their thickness abruptly decreases. The lower portion of the poorly dated sandstones of the Kurnub Group in Syria and Jordan, as well as their equivalent in Israel have been tentatively attributed to the lower and upper Aptian rather than to a lateral equivalent of the Chouf sandstones. This choice is based on a better coherence in the Aptian depositional systems from a regional standpoint. This tentative correlation remains to be fully supported by new biostratigraphic analyses. The whole of the lower Aptian is represented by a transgressive half-cycle (Jeita Fm.) made of a number of smaller carbonate sequences (megarippled calcarenites, rudist-bearing wackestones, etc.), often with emergent features at the top, and by a regressive half-cycle represented by the lagoonal mudstone facies of the Jezzine Fm. The barrier facies of the Jezzine Fm. is not known in Lebanon. In the coastal plain of Israel, thick calcarenites have been found at this stratigraphic level in exploration wells. These calcarenites could be part of the facies belt that separated the lagoonal mudstones from those of the open sea. If this view is correct, this barrier facies should continue to the north in offshore Lebanon (Fig. 3A). In west central Lebanon the upper Aptian (Dar El Beidar Fm.) is made up of a number of small shallow-water carbonate sequences. To the North, the thickness of this formation decreases markedly, mainly because it was eroded during the Albian emergence. Paleogeographic maps of the Aptian are hard to make due to stratigraphic uncertainties about the Kurnub sandstones in adjacent countries, as for example in Jordan where they onlap Paleozoic sandstones. The maps drawn for the upper Albian (Fig. 3B) to Turonian interval indicate a system of prograding and retreating carbonate platforms both in the coastal range of Syria and in the Rutbah high in Syria. Central and southern Lebanon remained subsident enough that only deeper-water mudstones were deposited there, at least during the Late Albian and Early Cenomanian. The Bekaa valley also remained a low. This suggests a synsedimentary vertical movement of the Yamouneh Fault

The Cretaceous of Lebanon in the Middle East (Levant)contextSerge Ferry, Yann Merran, Danie`le Grosheny, Moustapha MrouehTo cite this version:Serge Ferry, Yann Merran, Danie`le Grosheny, Moustapha Mroueh. The Cretaceous of Lebanonin the Middle East (Levant) context. Carnets de Geologie, Carnets de Geologie, 2007, CG2007(M02/08), pp.38-42. <hal-00166894>HAL Id: hal-00166894https://hal.archives-ouvertes.fr/hal-00166894Submitted on 12 Aug 2007HAL is a multi-disciplinary open accessarchive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come fromteaching and research institutions in France orabroad, or from public or private research centers.L’archive ouverte pluridisciplinaire HAL, estdestine´e au de´poˆt et a` la diffusion de documentsscientifiques de niveau recherche, publie´s ou non,e´manant des e´tablissements d’enseignement et derecherche franc¸ais ou e´trangers, des laboratoirespublics ou prive´s.Carnets de Géologie / Notebooks on Geology - Memoir 2007/02, Abstract 08 (CG2007_M02/08) The Cretaceous of Lebanon in the Middle East (Levant) context [Le Crétacé du Liban dans le cadre du Moyen-Orient (Levant)] Serge FERRY1,2Yann MERRAN1 Danièle GROSHENY3Moustapha MROUEH4Citation: FERRY S., MERRAN Y. GROSHENY D. & MROUEH M. (2007).- The Cretaceous of Lebanon in the Middle East (Levant) context. In: BULOT L.G., FERRY S. & GROSHENY D. (eds.), Relations entre les marges septentrionale et méridionale de la Téthys au Crétacé [Relations between the northern and southern margins of the Tethys ocean during the Cretaceous period].- Carnets de Géologie / Notebooks on Geology, Brest, Memoir 2007/02, Abstract 08 (CG2007_M02/08) Key Words: Cretaceous; Lebanon; sequence stratigraphy; incised valleys; paleogeography; volcanism Mots-Clefs : Crétacé ; Liban ; stratigraphie séquentielle ; vallées incisées ; paléogéographie ; volcanisme                                               1 Université Lyon 1, UMR 5125 PEPS, 43 Bd du 11 Novembre, Campus de La Doua, Bt. Géode, 69622 Villeurbanne cedex (France) 2 serge.ferry@univ-lyon1.fr3 Université de Strasbourg, Strasbourg 1, EOST, UMR 7517, 1 rue Blessig, 67084 Strasbourg (France) daniele.grosheny@univ-strasbg.fr4 Université libanaise de Beyrouth, Faculté d'Agronomie, Mont Liban, Horch Tabet (Lebanon)  mmroueh@ul.edu.lbManuscript online since May 15, 2007  [English] The Cretaceous succession of Lebanon was first described and dated mainly by DUBERTRET & VAUTRIN (1937), DUBERTRET (1955), and SAINT-MARC (1974), supplemented by the later contributions of SMIRNOVA & MROUEH (1980) for the Chouf Sandstones, NOUJAIM-CLARK & BOUDAGHER-FADEL (2001, 2002) for the Salima Formation. After two years of field work using facies sedimentology and sequence stratigraphy, and as part of the Middle East Basins Evolution (MEBE) Programme, we propose to divide the Cretaceous of Lebanon into three parts (Fig. 1):  (a) Valanginian to upper Aptian,   (b) upper Albian to Turonian, and   (c) Post-Turonian to Eocene. The first period is represented by several depositional sequences each bounded by emersion surfaces (D1 to D3, Fig. 1). The top of the Jezzine Fm. is unique because it is an emersion (karstified) surface in northern Lebanon but appears to be only a simple transgression surface in the South. During these emergences the coastal sedimentary prism was shifted into the present-day offshore. The transgressions that initiate all three sequences, including that of the upper Albian, which is coincident with the beginning of period 2, starts with the deposition of volcaniclastics that may continue into the overlying, deepening-up, shallow-water marine deposits. This relationship suggests that these depositional sequences were tectonically-controlled, that is the transgressions were initiated by the renewal of an extensional regime accompanied by volcanism. As a result of the strong lowering of base level, most emersions are associated with incised valleys, particularly spectacular in Northern Lebanon. The strongest is at the base of the upper Albian sequence (Fig. 2). It corresponds to an emergence that lasted throughout the whole lower to middle Albian interval. The second period corresponds to the emplacement of a large system of carbonate platforms that covered much more of the Arabian craton. Changes of relative sea-level created a number of depositional sequences (not shown on  Fig. 1) but drops in base level were not as great as those that occurred during the first period, except perhaps for the sequence ending near the Albian-Cenomanian boundary where an emersion surface of this age has been seen in the Anti-Lebanon and even in sections west of the Levant fault. These mild oscillations in relative sea-level are responsible of the spectacular sandwich of shallow-water (often rudist-bearing) carbonate facies alternating with finely-bedded or even laminated mudstones of Mount Lebanon. The Cenomanian-Turonian boundary, situated at the very base of the Ghazir Fm., is here coincident with the beginning of a deepening trend that peaks in the lower Turonian. 38 Carnets de Géologie / Notebooks on Geology - Memoir 2007/02, Abstract 08 (CG2007_M02/08)  Figure 1: Revised stratigraphy of the Cretaceous of Lebanon. (Formation names in red are new, 1 to 3 on left column refers to the three periods distinguished in the text). Figure 1 : Stratigraphie révisée du Crétacé du Liban. (Les noms de formations en rouge sont nouveaux, les chiffres 1 à 3 dans la colonne de gauche font référence aux trois périodes distinguées dans le texte). The third period corresponds to an acceleration of the drowning of the Arabian craton, probably as a response to the beginning of the collisional trend responsible for the closing of the Tethys. On the Levant platform, deposition of micritic limestones and chalks began and continued into Eocene times. Several paleogeographic maps have been drawn that take into account our results in Lebanon and also include, tentatively, published data from adjacent countries. The task is not easy mainly because of the many remaining uncertainties about the age of Lower Cretaceous sandstones in Israel, Syria and Jordan. Two of them are presented (Fig. 3). The (?) Berriasian – Valanginian sequence is preserved only in some half-grabens in northern Lebanon under the "transgressive" Barremian Chouf sandstones. The term "transgressive" should be considered in terms of accomodation space because the facies is fluvial at its base, and becomes deltaic to marginal marine only at its summit. These sandstones were deposited most abundantly in a W-E oriented saddle west of the Levant fault. East of the fault their thickness abruptly decreases. The lower portion of the poorly dated sandstones of the Kurnub Group in Syria 39 Carnets de Géologie / Notebooks on Geology - Memoir 2007/02, Abstract 08 (CG2007_M02/08) and Jordan, as well as their equivalent in Israel have been tentatively attributed to the lower and upper Aptian rather than to a lateral equivalent of the Chouf sandstones. This choice is based on a better coherence in the Aptian depositional systems from a regional standpoint. This tentative correlation remains to be fully supported by new biostratigraphic analyses. The whole of the lower Aptian is represented by a transgressive half-cycle (Jeita Fm.) made of a number of smaller carbonate sequences (megarippled calcarenites, rudist-bearing wackestones, etc.), often with emergent features at the top, and by a regressive half-cycle represented by the lagoonal mudstone facies of the Jezzine Fm. The barrier facies of the Jezzine Fm. is not known in Lebanon. In the coastal plain of Israel, thick calcarenites have been found at this stratigraphic level in exploration wells. These calcarenites could be part of the facies belt that separated the lagoonal mudstones from those of the open sea. If this view is correct, this barrier facies should continue to the north in offshore Lebanon (Fig. 3A). In west central Lebanon the upper Aptian (Dar El Beidar Fm.) is made up of a number of small shallow-water carbonate sequences. To the North, the thickness of this formation decreases markedly, mainly because it was eroded during the Albian emergence. Paleogeographic maps of the Aptian are hard to make due to stratigraphic uncertainties about the Kurnub sandstones in adjacent countries, as for example in Jordan where they onlap Paleozoic sandstones. The maps drawn for the upper Albian (Fig. 3B) to Turonian interval indicate a system of prograding and retreating carbonate platforms both in the coastal range of Syria and in the Rutbah high in Syria. Central and southern Lebanon remained subsident enough that only deeper-water mudstones were deposited there, at least during the Late Albian and Early Cenomanian. The Bekaa valley also remained a low. This suggests a synsedimentary vertical movement of the Yamouneh Fault. [Français] Le Crétacé du Liban (Fig. 1), dont la biostratigraphie est basée principalement sur les travaux de DUBERTRET et VAUTRIN (1937), de DUBERTRET (1955) et de SAINT-MARC (1974), avec les contributions de SMIRNOVA et MROUEH (1980) à propos des grès de base, ainsi que de NOUJAIM-CLARK & BOUDAGHER-FADEL (2001, 2002) pour la formation Salima, peut être subdivisé, après deux ans d'études de terrain effectuées dans le cadre du programme MEBE (Middle East Basins Evolution) en trois parties :  (a) Valanginien à Aptien supérieur,  (b) Albien supérieur-Turonien,  (c) Crétacé supérieur post-Turonien débordant dans l'Éocène. La première période est représentée par plusieurs séquences de dépôt, chacune séparée de l'autre par une émersion régionale qui a déplacé le prisme côtier dans l'offshore actuel. Le cortège transgressif de la plupart des séquences du Crétacé inférieur est marqué par une activité volcanique importante, ce qui suggère un contrôle tectonique des reprises de subsidence (extension), c'est à dire des transgressions. Beaucoup d'émersions sont marquées par des vallées incisées spectaculaires, notamment celle qui fait la transition entre la première et la deuxième période (Fig. 2). Cette émersion couvre en effet tout l'Albien inférieur et moyen, étant donné que l'ammonite Knemiceras syriacum, présente dans le cortège transgresssif de la séquence albienne, est connue pour n'apparaître qu'au sommet de l'Albien moyen (L. BULOT, comm. orale, 2006).  Figure 2: Albian incised valley at Beit Monzer, near the city of Ehden, in northern Lebanon. Figure 2 : Vallée incisée albienne à Beit Monzer, près de la ville d'Ehden, Nord Liban. 40 Carnets de Géologie / Notebooks on Geology - Memoir 2007/02, Abstract 08 (CG2007_M02/08)    Figure 3: Examples of paleogeographic maps under construction. (A: lower Aptian Jezzine Fm.; B: upper Albian Niha Fm.; DSTF, Dead Sea Transform Fault; SPF, South Palmyrides Fault; YF, Yamouneh Fault; CF, Carmel Fault; both DSTF and YF makes the Levant Fault). Figure 3 : Exemples de versions préliminaires de cartes paléogéographiques. (A: Formation de Jezzine, Aptien inférieur ; B: Formation de Niha, Albian supérieur ; DSTF, faille transformante de la Mer Morte ; SPF, faille du Sud Palmyrides ; YF, faille d'Yamouneh ; CF, faille de Carmel ; la combinaison des failles DSTF et YF est également appelée faille du Levant). La deuxième période est celle de la mise en place d'un vaste système de plates-formes carbonatées qui empiète sur le craton arabe et que l'on peut suivre sur toute sa périphérie. À l'exception d'une émersion généralisée sur tout le territoire du liban Nord vers la limite Albien-Cénomanien, l'amplitude des variations du niveau marin relatif est beaucoup moins importante que lors de la période précédente. Les variations limitées du niveau marin relatif ont engendré ce faciès carbonaté multi-couches (calcaires fins localement laminés / calcaires organogènes) si caractéristique du mont Liban et qui s'explique par un dépôt sur une plate-forme accidentée de dépressions "intra-shelf". La limite Cénomanien-Turonien est ici marquée par un simple ennoyage de la plate-forme carbonatée et ne s'accompagne pas de déformations tectoniques visibles. La troisième période est celle de l'accentuation de l'ennoyage du craton. Les plates-formes carbonatées disparaissent. La sédimentation devient partout crayeuse et se poursuit sans grand changement dans l'Eocène. Plusieurs cartes paléogéographiques ont été construites, en intégrant les données publiées concernant les pays limitrophes. Mais les incertitudes stratigraphiques qui subsistent font que ces cartes ne représentent que des tentatives, basées principalement sur la cohérence régionale des systèmes de dépôt dans les séquences successives. La séquence berriaso (?) – valanginienne n'est préservée que dans des demi-grabens du Nord-Liban sous la "transgression" des grès fluviatiles barrémiens du Chouf. Ceux-ci ne semblent préservés que dans la partie centrale du Liban et principalement à l'ouest de la faille du Levant. Partout ailleurs, les grès très mal datés du groupe Kurnub de Syrie et de Jordanie ou de son équivalent en Israel ont été attribués à l'Aptien supérieur, en s'appuyant, par 41 Carnets de Géologie / Notebooks on Geology - Memoir 2007/02, Abstract 08 (CG2007_M02/08) 42 analogie, sur les corrélations séquentielles réalisées d'Ouest en Est au Liban. Une reprise de subsidence (extension) semble donc piéger les apports fluviatiles uniquement au Liban, pas ailleurs, où l'espace d'accomodation limité ou nul ne le permet pas. L'Aptien inférieur est d'abord représenté par un demi-cycle globalement transgressif, complexe, fait plusieurs séquences émersives à faciès carbonatés (localement à rudistes) et grès. Le demi-cycle régressif est représenté par les calcaires de lagon de la formation Jezzine dont le faciès barrière (tel qu'il semble exister en Israel où il serait représenté par des calcarénites épaisses dans les puits de la plaine côtière) est sans doute situé dans l'offshore au droit de la côte libanaise actuelle (Fig. 3A). L'Aptien supérieur est fait de petites séquences à faciès peu profond qui n'empiètent guère sur le craton arabe. Dans l'extrème Nord du Liban, l'Aptien se réduit fortement. Il est plus ou moins bien préservé sous la surface d"érosion albienne. Il est difficile de proposer des cartes paléogéographiques régionales fiables pour cette tranche de temps, en raison des problèmes de datation des grès qui la représentent en Israel et en Jordanie plus à l'Est où ils transgressent directement les grès paléozoïques. Les cartes de faciès réalisées pour l'intervalle Albien supérieur-Turonien (Fig. 3B) mettent en évidence un système de plates-formes progradant de façon répétitive à partie de zones hautes et comblant des sillons "intra-shelf". Il semble que la faille du Levant ait eu un rôle dans l'entretien de la zone globalement basse de la Bekaa. Bibliographic references / Références bibliographiques DUBERTRET L. (1955) – Carte géologique du Liban au 200 000e.- Ministère des Travaux publics, Beyrouth. DUBERTRET L. & VAUTRIN H. (1937) – Révision de la stratigraphie du Crétacé du Liban. Notes et Mémoires, Haut-Commissariat de la République Française en Syrie et au Liban, t. II, p. 43-73. NOUJAIM-CLARK G. & BOUDAGHER-FADEL M.K. (2001).- The larger benthic Foraminifera and stratigraphy of the Upper Jurassic/Lower Cretaceous of central Lebanon.- Revue de Micropaléontologie, Paris, vol. 44, N° 3, p. 215-232. NOUJAIM-CLARK G. & BOUDAGHER-FADEL M.K. (2002).- "Larger" foraminifera assemblages and stratigraphy of the Upper Jurassic Bahness Complex Formation, Central Lebanon.- Revue de Paléobiologie, Genève, vol. 21, N° 2, p. 679-695. SAINT-MARC P. (1974).- Étude stratigraphique et micropaléontologique de l'Albien, du Cénomanien et du Turonien du Liban.- Notes et Mémoires sur le Moyen-Orient, Muséum National Histoire Naturelle, Paris, t. XIII, 342 p. SMIRNOVA S. & MROUEH M. (1980).- Caractère palynologique du grès de base du Liban (Rayon Hidele).- 26e Congrès Géologique International, Résumé - Abstracts, Paris (7-17 juillet 1980), vol. I, section 3, p. 183.  

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The Cretaceous of Lebanon in the Middle East (Levant) context

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