0012-9402/06/020237-170012-9402/06/02■■■-■■ Eclogae geol. Helv. 99 (2006) 237–253 DOI 10.1007/s00015-006-1186-9 Birkhäuser Verlag, Basel, 2006 Oligocene-early Miocene transgressive cover of the Betic-Rif Internal Zone. Revision of its geologic significance FRANCISCO SERRANO1,CARLOS SANZ DE GALDEANO2,KHALIL EL KADIRI3,ANTONIO GUERRA- MERCHÁN1,ANGEL CARLOS LÓPEZ-GARRIDO2,MANUEL MARTÍN-MARTÍN4 & RACHID HLILA3 Key words: Oligocene, early Miocene, Ciudad Granada group, Viñuela group, nappe emplacement, extensional events, Internal Betic Cordillera, Internal Rif ABSTRACT RESUME The Oligocene-early Miocene sedimentation in the Betic-Rif Internal Zone Les séries tertiaires assurant la couverture transgressive de la zone interne bé- (BRIZ) occurred during the same time interval as the main tectonic events tico-rifaine (BRIZ) sont inclues dans le même intervalle d’âge, Oligocène- that are classically considered responsible for the structuring of this zone. Miocène inférieur, que les événements tectoniques responsables, pour certains Therefore, its paleogeographic and tectonic significance has been the subject auteurs, de la structuration majeure de la dite zone. C’est pourquoi, l’interpré- of much controversy. The sedimentation developed in two successive groups tation tectono-sédimentaire de ces séries suscitait de vives controverses. Stra- of formations: the Ciudad Granada group of late Oligocene–Aquitanian in age tigraphiquement, deux groupes sédimentaires sont distingués : le groupe Ciu- and the Viñuela group of Burdigalian p.p. in age. The former consists of red- dad Granada d'âge Oligocène supérieur–Aquitanien et le groupe Viñuela dish marls containing clastic intercalations of Malaguide origin, while the d'âge Burdigalien p.p. Le plus ancien contient de pélites rougeâtres et des cou- Viñuela group is made up of siliceous-intercalated marlstones and lime-poor lées détritiques d’origine “Malaguide”, alors que le groupe Viñuela se compo- pelites, with a basal coarse-grained clastic material inherited from both the se de marnes, localement siliceuses, et de décharges conglomératiques à élé- Malaguide and Alpujarride complexes. An overview of all the outcrops of the ments hérités à partir des complexes Malaguide et Alpujarride. La révision BRIZ leads to the conclusion that the two groups are closely related both geo- générale des affleurements dans toute la BRIZ permet de conclure que les graphically and tectonically. The paleogeographic, tectonic, stratigraphic and deux groupes appartenaient initialement aux mêmes dépocentres, sans que le sedimentary relationships suggest that there was no nappe stacking stage be- puisse constater de phase de structuration en nappes pendant la période qui tween the two groups in the BRIZ. The transition from Ciudad Granada to séparait leur dépôt. Le passage de Ciudad Granada à Viñuela semble dû à un Viñuela seems to have been the result of a transtensive tectonic event proba- événement tectonique transtensif, lié probablement à la dérive vers l’ouest de bly related to the westward migration of the BRIZ and to the opening of the la BRIZ et à l’ouverture conséquente des bassins Algéro-Provençal et d’Albo- Algero-Provençal and Alboran basins. This tectonic disturbance would have ran. Cette perturbation tectonique aurait généré un système de horsts et de caused a severe subsidence in the downfaulted blocks, thus deepening the de- grabens très contrastés. Des zones à forte subsidence étaient alors juxtaposées position zones; at the same time, the rapid uplifting of upfaulted blocks would à des horsts exposant les unités Alpujarrides. Ces dernières peuvent servir à la have uncovered Alpujarride units, thus comprising the basement and the fois de substratum et de source de matériel clastique pour le groupe Viñuela. source of detritics for the Viñuela group. Introduction continental domain was located N of Africa from which it de- The Betic Cordillera and Rif constitute the western extremity tached since the Cretaceous, resulting then in a northward-de- of the peri-Mediterranean Alpine chain. Their common inter- riving microplate between Africa and Eurasia (e.g., synthesis nal zone (henceforth BRIZ, Fig. 1), formed part of the Me- by Andeweg, 2002). During the Oligocene, the domain was somediterranean block (Durand-Delga & Fontboté 1980), i.e., fragmented by the rifting of the Algero-Provencal basin (west- the so-called Alkapeca (Alboran-Kabylian-Peloritani-Calabri- ern Mediterranean), so that its WSW-migrating part (the Alb- an domain, Bouillin et al. 1986). During the Jurassic times, this oran block, Andrieux et al. 1971) become wedged between the 1 Departamento de Ecología y Geología, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, 29071 Málaga, Spain 2 Instituto Andaluz de Ciencias de la Tierra (CSIC-Univ. Granada), Facultad de Ciencias, 18071 Granada, Spain 3 Faculté des Sciences, Département de Géologie, B.P. 2121, 93003 Tétouan, Morocco. 4 Dpto. Ciencias de la Tierra y Medio Ambiente, Universidad de Alicante AP-99, 03080 Alicante, Spain Oligocene-early Miocene in the Alboran domain 237 Fig. 1. General scheme of the Betic-Rif orogen and geographic location of the Oligocene-early Miocene transgressive formations over the BRIZ (CG: Ciudad Granada group; V: Viñuela group). 1. Sierra Espuña sector; 2. Chirivel sector; 3. Southern Sierra Almagro; 4. Northern Sierra Cabrera; 5. South-western Guadix basin; 6. North-eastern Granada basin; 7. South-eastern Granada basin; 8. La Viñuela sector; 9. Colmenar sector; 10. Casabermeja; 11. Cortijo Cherino; 12. Northern Almogía; 13. Malaga sector; 14. Northern Cártama; 15. Alozaina-Tolox sector; 16. Guaro sector; 17. Ardales sector; 18. San Pedro de Alcántara sector; 19. Ceuta-Fnideq sector; 20. Zem sec- tor; 21. Tetuan-Sidi Abdeslam sector; 22. Tamezzakht sector; 23. Talembote sector Iberian block and the African plate, thus forming the Gibraltar the Malaguide. Tectonic movements and the linked nappe em- Arc. Finally, the westward prolongation of the Mediterranean placement initially had a north mean direction (NW, N or NE). rifting thinned the axial zone of the BRIZ. The resulting deep Subsequently, during the westward migration of the BRIZ, im- internal trough originated the Alboran Sea (Sanz de Galdeano portant W and WSW displacements occurred in the Rif 1990; Comas et al. 1992). (Frizon de Lamotte et al. 1991), while movements in the Betic Three main tectonically stacked complexes can be distin- Cordillera were towards the W-NW (Kirker & Platt 1998; guished in the BRIZ. These are from bottom to top: the Neva- Luján et al. 2000; among others). Some units locally underwent do-Filabrides (not present in the Rif), the Alpujarrides (i.e, Ri- severe backthrusting and rotations. fian Sebtides) and the Malaguides (Rifian Ghomarides). Orig- During the Cretaceous to early Miocene, the Maghrebian inally, the complexes that today occupy the highest tectonic Flysch trough developed between these domains and the positions were located in more southerly positions (Durand- African plate (Durand-Delga 1972). The paleogeographic tran- Delga 1980; Wildi 1983). In addition, the Dorsal is usually sition between the calcareous Dorsal and the Flysch trough cor- identified as occupying a distinct domain extending south of responded to the Predorsalian and the Mauretanian zones, re- 238 F. Serrano et al. Table 1. Transgressive formations of the Sector Formation (authors) Group Oligocene–early Miocene over the BRIZ and BETIC CORDILLERA group assigned in this paper. Sector numbers cor- 1. Sierra Espuña El Niño Fm. (Martín-Martín 1996) Viñuela respond to those in Fig. 1. Oligo-Aquitanian of the "zone limite” (Paquet 1969) Ciudad Granada or Río Pliego Fm. (Martín-Martín 1996) Bosque Fm. (Martín-Martín 1996) Ciudad Granada 2. Chirivel Espejos Fm. (Soediono 1971) Viñuela Fuentes Fm. (Soediono 1971) Viñuela Ciudad Granada Fm. (Mac Gillavry 1963) Ciudad Granada Frac Fm. (Soediono 1971) Ciudad Granada Cortijo del Perro Malo Fm. (Soediono 1971) Ciudad Granada 3. SE Sierra Almagro Fuente Álamo Fm. (Völk 1967) Viñuela 4. N Sierra Cabrera Fuente Álamo Fm. (Völk 1967) Viñuela 5. SW Guadix Basin Los Alamillos Fm. (Rodríguez-Fernández 1982) Viñuela 6. NE Granada Basin Los Alamillos Fm. (Rodríguez-Fernández 1982) Viñuela 7. SE Granada Basin Base del Tramo de Murchas (González Donoso 1977-78) Viñuela 8. La Viñuela Viñuela Fm. (Vera 1969) Viñuela 9. Colmenar Majiaza Complex pro-part (Peyre 1974) Viñuela 10. Casabermeja Upper Oligocene of the “Bético de Málaga” pro-part (Didon et al. 1961) Viñuela 11. Cortijo Cherino Burdigalian sediments (Peyre 1974) Viñuela 12. N Almogía Burdigalian sediments (Peyre 1974) Viñuela 13. Malaga Viñuela group (Serrano et al. 1995) Viñuela Ciudad Granada group (Serrano et al. 1995) Ciudad Granada 14. N Cártama Viñuela group (Sanz de Galdeano et al. 1993) Viñuela 15. Alozaina-Tolox Las Millanas Fm. (Bourgois et al. 1972a) Viñuela Alozaina Fm. (Bourgois et al. 1972b) Ciudad Granada 16. Guaro Viñuela group (this work) Viñuela 17. Ardales Pantano de Andrade Fm. (Bourgois 1978) Ciudad Granada 18. San Pedro de Alcántara San Pedro de Alcántara Fm. (Didon et al. 1973) Viñuela RIF 19. Ceuta-Fnideq Burdigalian sediments (El Kadiri et al. 2000) Viñuela Fnideq Fm. (Durand-Delga et al. 1964) Ciudad Granada 20. Zem-Zem Fnideq Fm. (Durand-Delga et al. 1964) Ciudad Granada 21.Tetuan-Sidi Abdeslam Sidi Abdeslam Fm. (Durand-Delga et al. 1964) Viñuela Boujarrah section (Maaté et al. 1995) Viñuela Fnideq Fm. (Durand-Delga et al. 1964) Ciudad Granada 22. Tamezzakht Oligo-Early