The Iberian Middle Jurassic carbonate-platform system: Synthesis of the palaeogeographic elements of its eastern margin (Spain) 1.1. G6mez a,*, S.R. Femandez-L6pez b a Dpto. EstratigTajia, Facultad de Ciencias Geologicas (UCM) e lnstituto de Geologia Economica, (CS1C-UCM), 28040 Madrid, Spain b Dpto. Paleontologia, Facultad de Ciencias Geologicas (UCM) e lnstituto de Geologia Economica, (CSIC-UCM), 28040 Madrid, Spain Abstract During the Middle Jurassic, the domain of the Iberian and Catalan Coastal ranges of eastern Spain was occupied by a system of fault-controlled carbonate platforms that flanked the Iberian Massif to the East. This platform system marked the transition between the shelves of the Alpine Tethys and the Central Atlantic Ocean. The palaeogeographic reconstruction of the Iberian Middle Jurassic platfOlm system is based on more than 199 surface sections and 37 wells. From southwest to northeast, eight main palaeogeographic elements with associated characteristic facies are recognized. These represent a system of horsts and grabens. In the southwest, the Internal Castilian Platform is characterized by the frequently dolomitized oolitic and restricted facies of the Yemeda FOlmation. To the nOliheast, the NW-trending open-marine carbonate environments of the External Castilian and Aragonese platforms were separated by the fault-controlled El Maestrazgo High that is characterized mainly by the dolomitized Rafales Formation. The External Castilian and Aragonese platforms consist from bottom to top of the micro filament mudstones to wackestones of the El Pedregal Formation, the bioclastic and oolitic grainstones to packstones of the Moscardon FOlmation, and the Domefio Formation, that reflects a return to an open-marine low-energy wackestone to mudstone facies, locally containing patches of oolitic grainstones. The highly subsiding Tortosa Platform, represented by the Sant Blai, Cardo and La Tossa formations, is bounded by the dolomitic facies deposited on the El Maestrazgo and the TalTagona highs, and by the Catalan Massif where no Middle Jurassic deposits have been recorded. The open-marine facies and condensed sections of the Beceite Strait separated the Aragonese and Tortosa platforms. A regional stratigraphical gap spanning the upper Callovian Lamberti Zone to the lower Oxfordian Cordatum Zone is evident. A system of northwest- and nOliheast-trending normal faults controlled thickness and facies distribution. Data from the Iberian carbonate-platform system indicate that expanded sections were not necessarily associated with open-marine environments. Condensed and expanded sections are developed in open and restricted-marine facies, even on such palaeogeographic highs as the El Maestrazgo High. Restricted and shallow-marine environments occasionally developed in patis of the External Castilian Platform. Keywords: Middle Jurassic; Carbonate platforms; Stratigraphy; Palaeoenvironments; Palaeogeography; Spain * Corresponding author. Tel.: +34 913944783; fax: +34 913944808. E-mail addresses: jgomez@geo.ucm.es (J.J. G6mez), sixto@geo.ucm.es (S.R. Femandez-L6pez). 1. Introduction Regional Middle Jurassic palaeogeographic recon­ structions of the early opening stage of the Central Atlantic Ocean and the Alpine Tethys indicate that the East-Iberian area was occupied by a carbonate-plat- form system, the fades development and subsidence patterns of which were controlled by active faults (Fig. 1; Ziegler, 1990; Bassoullet et aI., 1993; Enay et aI., 1993; Thierry, 2000; Vera, 2001, 2004; Vera et aI., 2001; Stampfli and Borel, 2004). In the fold-and-thrust belts of the Iberian and Cat­ alan Coastal ranges of Spain, which evolved by Pa­ leogene inversion of Mesozoic rifted basins (Salas et aI., 2001), Middle Jurassic carbonates are exposed Wlder outstanding outcrop conditions over a distance of more than 500 km. In the context of our studies, we � Cratonic D Shallow mann&­� high continental basin analysed in these areas 199 Middle Jurassic surface sections and data from 37 boreholes (Fig. 2). This permitted us to develop a detailed reconstruction of the palaeogeographic elements of the East-Iberian Middle Jurassic carbonate-platform system. In the ibe­ rian Range, Middle Jurassic carbonates, formerly at­ tributed to the "middle portion" of the Chelva Formation (Gomez and Goy, 1979), were recently subdivided into several hthostratigraphic Wlits (Gomez and Fernandez-Lopez, 2004a,b) on the basis of their distinct fades development that can be related Oceanic basin Fig. 1 . Middle Jurassic palaeogeography of the Western Tethys and the Proto-Atlantic Ocean (Ziegler, 1990; Stampfli and Borel, 2004; modified) and location of the studied area. Ab: Alboran. Ad: Adria s. str. Ap: Apulia s. str. Bu: Bucovinian. CL: Campania Lucania. Cn: Carnic-julian. GB: Grand Bank. hA: High Atlas. He: Helvetic rim basin. Ig: Igal trough. La: Lagonegro. LBM: London-Braband Massif. mA: Middle Atlas. MC: Massif Central High. NFB: East Newfmmdland Basin. Pa: Panonnides. PI: Pelagonian. Se: Sesia (western Austroalpine) . Si: Sicanian. SI: Slavonia. Tu: Tuscan. Tz: Tizia. UM: Umbria-Marches. to their palaeogeograpbic setting (Fig. 3). In the Cat­ alan Coastal Range, Cadillac et al. (1981) and Fernim­ dez-L6pez et al. (1996, 1998) had analysed the lithostratigraphy of Middle Jurassic deposits. Detailed palaeontological studies of these deposits, containing ammonites, allowed for a high-resolution biostrati­ graphic subdivision of this sequence at the scale of zones, subzones and horizons (Hinkelbein, 1975; G6mez, 1979; Pemandez-L6pez, 1985; Melendez, 1989). In this study, biostratigraphical data are referred to the standard zones of ammonites. During the Middle Jurassic, the so-called Iberian Basin was occupied by a complex system of epiconti­ nental carbonate platforms that in many cases were tectonically controlled. Up-thrown blocks formed palaeogeographic highs that were characterized by shal­ low-water depositional environments. Areas between these highs were largely dominated by open-marine -- -. GUADALAJARA /- '1...- o _ Outcrops of Jurassic deposits �" • Oil well " environments, Wlder which low-energy fossil-rich am­ monite-bearing fades developed, suggesting that they were partly connected to the open ocean (AureU et aI., 2002, 2003; Fernimdez-L6pez and G6mez, 2004). From southwest to northeast, eight main palaeogeographic elements can be recognized that were associated with characteristic facies, and that represent a horst and graben system (Fig. 4). In the southwestern area, the Internal Castilian Platform was attached to the Iberian Massif. To the northeast, the fault-controlled El Maes­ trazgo High sepamted the NW-trending open-marine External Castilian and Aragonese carbonate platforms. The highly subsident Tortosa Platform was delimited to the north by the Tarragona High and the Catalan Mas­ sif, that are devoid of Middle Jurassic deposits, and to the south by the El Maestrazgo High. The Beceite Strait fonned a tmnsitional area between the Aragonese and the Tortosa platforms. -. Cl - , '. . - I'VALENClA 0 10 20 3040 50 km The main objective of our study was to synthesize the palaeogeography and facies distribution on the eastern margin of the Iberian carbonate-platform sys­ tem. The different fault-bounded platfonns show char­ acteristic facies variations, ranging from restricted and shallow-marine to open and deep-marine environ­ ments that are associated with condensed and expand­ ed sections (G6mez and F ernandez-L6pez, 1994; 2004a,b; Ferruindez-Lopez and Gomez, 2004). 2. Internal Castilian Platform The Middle Jurassic Internal Castilian carbonate plat­ fonn flanks the Iberian Massif to the east (Fig. 4). It is characterized by the high-energy oolitic bars and asso­ ciated low-energy, restricted shallow-marine facies of the Yemeda Formation. Owing to successive post-Juras­ sic erosional events, the transition between these carbo­ nates and a continental facies is no longer preserved. This lithostratigraphic unit consists of oolitic grain­ stones to packstones, sometimes including ooids and/or bioclasts, which are interbedded with calcareous mud­ stones to wackestones that can be the dominant facies in some areas. These carbonates, which are stratified into thick beds, are locally partial or entirely dolomi­ tized. The unit often contains grainstone to packstone bodies which display a well preserved bar morphology, showing planar and through cross-bedding, wave rip­ ples, bioclastic rills and bioturbation. Locally, low angle planar cross-lamination, algal laminae and fenes­ tral porosity occur. Common are thickerung- and coars­ ening-upward sequences generated by the migration of oolitic bars over low-energy restricted mudstones to wackestones. Similarly, successions of calcareous oo­ litic and bioclastic grainstones are common. Thickness of the Yemeda Fonnation in the type section (YE in Fig. 2; Gaibar-Puertas and Geyer, 1967, 1969; Vial­ lard, 1973) attains about 250 m, marking a subsident area that defmes the Enguidanos Depocentre (Fig. 4; Femindez-L6pez and G6mez, 2004; G6mez and Fer­ nandez-L6pez, 2004a). Another reference section is the Embalse de Contreras section, where this unit exceeds a thickoess of 225 m. Partial sections from Buenache de la Sierra and La Toba have been described by Viallard (1973) and Morillo-Velarde and Melendez­ Hevia (1981). The most fossiliferous deposits of this restricted internal platform area contain occasional remains of benthic organisms such as bivalves, echi­ noids, calcareous algae, bryozoans, brachiopods, for­ aminifers and gastropods. Ammonites and belemnites are very scarce or absent in the whole unit. Yet, in the Yemeda section, where micritic low-energy restricted facies dominate, exceptionally Bajocian stephanocera­ tids in its lower and middle part, and Procerites, Fig. 2. Outcrops of the lurassic sediments in the Iberian Range and in the Catalan Coastal Range, shov.ring the sections and wells studied in this work. Abbreviations of the surface sections: AA: Aras de Alpuente. ACI: Alcublas-I. AC2: Alcublas-2. AC3: Alcublas-3. AC4: Alcublas-V AF: Alfara. AG: Aguaton. AH: Almohaja-N. AJ: Areos de lalon. AL: Albarracin. ANI: Andorra-I. AN2: Andorra-2. AN3 : Andorra-3. AO: Alcotas. AP: Arroyo Picastre. AR: Arilio. AS: Alcorisa-E. ATI: Alustante-S. AT2: Alustante-E. AU: Aguilon. AV: Barranco del Avellanar. AZ: Adzaneta­ NE. BB: Ababuj . BC: Balneario de Cardo. BD: Barranco de la Cedrilla. BE: Barranco de las Estacas. BG: Rio Bergantes. BH: Barranco de la Hontanilla. BI: Barranco de Milles. BL: Barranco de Valdecastillo. BM: Barranco Moro. BN: Buenache de la Sierra. BO: Barranco Las Ennitas. BP: Barranco del Sapo. BS: La Buenafuente del Sistal. BT: Beceite. BU: Buiiol. BV: Barranco del Vall. BZ: Belchite. C: Barranco La Canaleja. CA: Caudiel. CB: Corbalan-E. CD: Cedrillas. CE: Cella. CG: Coll de l' Argila. Cl: Chilches. CL: La Cerredilla. CM: Campillos-Paravientos. CN: Canales. CN: Caiiada Vellida. CO: Codes. CR.: Bronchales. CS: Cap de Salou. CT: Villar de Cobeta. CU: Concud. CV: La Caiiada de Verich. CW: Corbalan-W. CHI: Alcoroches-W. CH2: Alcoroches-N\V. D: Molino Romedianos. DG: La AlmlUlia de Dofia Godina. DM: Domei'io. DR: Aladren. EB: Embalse San BIas. EC: Coll del Caragol. EG: En Grillo. EH: Embalse de Hijar. Ell: Ejulve-SW. El2: Ejulve-S. ERI: El Coscojar. ER2: Entrambasaguas. ET: Embalse de Contreras. EZ: El Cabezo. FN: Frias de Albarracin-N. FS: Frias de Albarracin-S. FW: Frias de Albarracin-W. FZ: Fuentelsaz. G: Rambla La Gotera. GA: Gea de Albarracin. GC: Graja de Campalbo. GE: Embalse del Generalisllno . GI: Aliaguilla. GP: Embalse de Gallipuen. GS: Gaibiel-S. GU: Guadalaviar. GW: Enguidanos-N\V. HP: Hoya del Peral. HR.: Barranco del Chorrillo. HT: Hontanar. HU: Huerguina. RV: Chelva. ll.,: Cillas. lA: laulin. 10: Henarejos. lV: lavalambre. LC: La Cierva. LD: Lidon. LE: Lecera. LH: Las Higueruelas. LM: La Olmeda. LO: Coscollosa. LV: Les Voltes. LL: Llaberia. M: Moscardon. :MA: Mas Nueva. MC: Masia de la Sisca. MD: Masada del Diablo. ME: Maranchon­ SE. MG: Monteagudo de las Salinas. MI: Miravete. ML: Molinos. :MN: Montoro. MO: Montornes. MR Mas Riudoms. MS: Maranchon-S. MT: Masada Toyuela. MU: Montes Universales. :MY: Moneva-E. MY: Moyuela. NA: Buefia. NE: Alcaine. NG: Noguera. Nl: Montanejos. OE: Miravet. OG: Ojos Negros. ON: Obon-N. OS: Oset. OW: Obon-W. P: Sagunto. PA: Palomar de Arroyos. PC: Puerto del Caballo. PD: Pancrudo. PE: Peracense. PI: Espina. Pl: Pajaroncillo. PL: Pinilla de Molina. PMI: Areos de las Salinas. P:M2: La Puebla de San Miguel-2. PM3: La Puebla de San Miguel-3. PN: Pina de Montalgrao. PP: Rio Pena. PT: Peralejos de las truchas. PZ: El Pedregal. RB: Ribarroja. RC: Ricla. RE: Rubielos de la Cerida-E. RF: Rafales. RG: Ribagorda. RJ: Torrijas. RN: Renales. RO: Revolcadero-Cucutas. RR: Barranco del Grevolar. RS: Rambla del Salto. RT: Carlades-L'Embarronat. RV: Riodeva. RW: Rubielos de la Cerida-W. SA: Sarrion. SB: Sant Blai. SC: Sot de Chera. SE: Santa Eulalia. SI: Siete Aguas-NE. SL: Salada. SM: Santa Cruz de Moya. SN: Sinarcas-N. SP: Sierra de El Pobo. SR Serretilla. ST: Rio de Estrets. SU: Sierra de la Bicuerca. TA: Torre las Areas. TB: La Toba-S. ID: Tordellego. TE: La Toba-E. TI: Toril. Tl: Tuejar. TL: Tejadillos. TM: Tonnon. TO: Tosos. TQ: La Tranquera. TR Checa-SW. TT: Beteta. TU: Tunniel. TV: TIvissa. TY: Tivenys. UA: Ufia. US: Chuvellus. V: Vallanca. VB: Vistabella del Maestrazgo-E. VC: Villar del Cobo. VD: Poveda de la Sierra. VF: Fordenchana. VII: Villar del Humo. VI: Villel. VN: Vandellos. VS: Valsalobre. VT: Villar de Tejas. XP: Xerta-Pauls. YE: Yemeda. YU: Talayuelas. ZA: Zafrilla. reineckeids and hecticoceratinae of Bathonian and Cal­ lovian age in its upper part have been found (Gaibar­ Puertas and Geyer, 1967, 1969; and unpublished data of the authors). High-energy facies belts, reflecting the action of waves, tides and storms, characterize the shallow­ water Middle Jurassic Internal Castilian carbonate plat­ form. It corresponds to a belt of bars and charmels and is characterized by high rates of carbonate production and accumulation. Oolitic and bioc1astic grainstone bars system is associated with washover and beach facies. Low energy micritic facies were deposited between these high-energy bars and in extensive lagoons, as well as tidal flat deposits. In the southern parts of the Castilian Platform, the Montes Universales Fault marks the bOWldary between its internal and external areas. In the northern parts of the Castilian Platform, the bound­ ary between internal and external areas is more transi­ tional, delineating a northwestern-trending belt of fine­ grained limestones, oolitic, bioc1astic and oncolitic packstones to grainstones and dolomitic deposits that are organized into shallowing-upward sequences. South of La Mancha Fault, the oolitic facies continues south­ ward, but its chronostratigraphic attribution is still Wl­ certain in these areas. The Montes Universales and La Mancha faults delineate a rapidly subsiding area that corresponds to the Enguidanos Depocentre in which tectonically controlled subsidence rates were fully com­ pensated by sedimentation rates, as evidenced by the persistence of shallow-water restricted facies during most of Middle Jurassic. 3. External Castilian and Aragonese platforms On the External Castilian and Aragonese carbonate platforms, which outcrop in the Iberian Range, most of the Middle Jurassic is represented by open-marine facies that commonly contain ammonites, allowing for a high-resolution biostratigraphic zonation (Hinkel­ bein, 1975; Fernandez-L6pez, 1985; Fernandez­ L6pez and G6mez, 1978; Melendez, 1989). Three lithostratigraphic Wlits are recognized, that can be fol­ lowed over the entire Iberian Range, and which permit a detailed reconstruction of the palaeogeographic and palaeotectonic evolution of these platforms. From bot­ tom to top, these are the El Pedregal, Moscardon and Domefio formations. 3.1. El Pedregal Formation The El Pedregal Formation consists of lime mud­ stones and wackestones containing bioc1asts, mainly bivalves (micro filaments ), echinoderms and pellets. These may contain interbedded marls, sometimes bio­ clastic, which in the upper part of this unit locally constitutes an alternation of marls and limestones. Chert nodules are common in limestones. In the basal parts of this formation, interbedded horizons consisting of limestones containing ferruginous and/or phosphatic ooids are common (Geyer et aI., 1974). These are associated with the strati graphical gap that is located at the base of the El Pedregal Formation. On the Aragonese Platform, ferruginous and/or phosphatic ooids are also common in the uppermost levels of this unit (Mouterde et aI., 1978; Fernimdez-L6pez, 1985; G6mez and Ferruindez-L6pez, 1994). In the NW Exter­ nal Castilian Platform, peritidal dolomitic limestones and mudstones, showing microbial laminae and mud­ cracks (Fernimdez-L6pez, 1997), as well as oolitic grain­ stones, are interbedded in the lower part of the sections (Fig. 5). Mounds formed by volcanic rocks occur on the SE External Castilian Platform (Figs. 4 and 5; Gautier, 1968, 1974; G6mez et aI., 1976; G6mez, 1979, 1985a,b; Orti and Vaquer, 1980; Fernimdez-L6pez et aI., 1985; Martinez Gonzalez et aI., 1997, 1998; Cortes, 2001). In the NW and Central Castilian platforms, sponge build­ ups and marls are common in the upper part of the El Pedregal Formation (Fig. 5; Fernimdez-L6pez et aI., 1978; Fernandez-L6pez, 1985; G6mez, 1985a,b, 1991; Friebe, 1995). Zoophycos and Thalassinoides are com­ mon, and occasionally bioclastic rills, ferruginous crusts, and remobilization surfaces are recognized. These ich­ nofossils are widely represented in external platform facies of the Middle Jurassic deposits, ranging from restricted and shallow to open and deep environments (Fernandez-L6pez, 1997; Olivero, 2003; Knaust and Hauschke, 2004). The El Pedregal Formation is generally organized into shallowing-upward sequences, usually composed of a lower marly and an upper calcareous part, which is bioturbated and, on occasions, contains build-ups of sponges and algae or dolomitic facies. The tops of many of these sequences are marked by hardgroWlds, which are characterized by borings, ferruginous crusts, glauconitic, phosphatic and bioc1astic carbonates, as well as reworked fossils (reelaborated and resedimented fossils in Fernimdez-L6pez, 1991). The thickness of the El Pedregal Formation reaches more than 150 m in the Pozuel and Casinos depocentres (Fig. 4). On the Central External Castilian Platform the thickness of this unit varies between 60 and 80 m. On the Aragonese Platform, remarkable thickness varia­ tions are observed, ranging between 8 m in the Andorra-l section and 45 m in the Ricla section (Fig. 2). CATALAN COASTAL RANGE Domet1OFm Domet1OFm La Tossa Fm Fig. 3. Middle Jurassic lithostratigraphic lUlits and the shallowing and deepening cycles of the Iberian and Catalan Coastal ranges, referred to the chronostratigraphical lUlits. Remains of ammonites, belemnites and benthic organisms, such as bivalves, brachiopods, echinoderms, serpulids, gastropods, bryozoans, sponges and calcare­ ous algae, are abWldant in some levels. The base of the El Pedregal Formation coincides with the upper part of the Aalenian Murchisonae Zone, although Aalenian and lower Bajocian deposits are usually included in con­ densed sections, whilst its top is slightly diaclrronous at a regional scale. It corresponds to the Bajocian Nior­ tense and Garantiana zones (Figs. 3 and 5). The El Pedregal Formation was deposited on an external platform, dominated by low-energy, open-ma­ rine, normal salinity, shallow-water environments, oc­ casionally affected by storms. Microbial laminae, mud-cmcks and karstification smfaces indicate local, occasional emersion in mudstones related to deposi­ tion in confined shallow-marine environments (Fernan­ dez-L6pez and G6mez, 1990b). In the upper part of the El Pedregal Formation, facies, taphonomy and palaeo­ biological evidence (Fernandez-L6pez and G6mez, 2004) indicate depth increasing and, presumably, facil- itation of connections with open-sea Atlantic and West­ ern Tethys waters. 3.2. Moscardon Fonnation The Moscardon Formation consists mainly of bio­ clastic grainstones to packstones on which crinoids, ooids and intraclasts are sometimes abWldant. Bioclas­ tic wackestones and mudstones are locally represented. The Wlit, which commonly forms steep escarpments, is usually bedded in layers which may surpass 3 m in thickness. Chert nodules as well as Zoophycos and Thalassinoides are locally common. Among the sedi­ mentary structures, planar and festoon cross-lamination, ripples, bioclastic rills, and sedimentary bodies showing bar morphology are common. On the Aragonese Plat­ form, the Moscardon Formation consists of calcareous packstones to boundstones forming sponge build-ups (Fig. 5; Femimdez-L6pez and Aurell, 1988). These lithologies and structures are generally organized into shallowing-upward sequences with a lower part of cal- L£(;(NO Cosoblonco-I + due to �Middle J�r055jc eedjment, portially " "obsent due to ero .. on or r.o Oeposi\ion � lntemcl plotform foeln � TronsilionGI (oc;ies bet .... een internel c.:.J O nd •• ternol plotforme. � E.I.rnol plotform conde"eed L..:d sections D External plotfofn) focie!. Ammonoids alio"" dot,ng ot the lone scale. Fig. 4. Palaeogeographic reconstruction of the different platfonns in the eastern margin of the Iberian platform system during Middle Jurassic. From southwest to northeast the Internal Castilian Platform, the External Castilian Platfonn, divided into the NW, Central and SE External Castilian platforms, the El Maestrazgo High, the Aragonese Platform and the Tortosa Platform, linked by the Beceite Strait, the Tarragona High and the Catalan Massif. AAAGONESE PlATFORM � Dolornitic facies r:-:-:l Ootitic groinstone and � pockstone _ Crionoidol grainstone and pockstone � Bioclastic rnudstone and � wockestone NW NW Limestones with sponges, � including buildups _ Rock of volcanic origing, forming mounds � Mudstone artd wackestone � in thick be}1s (I �ft) . and in thin beds (righl) _ Limestone and mort _ Mori and limestone RI Mudstone and wackestone _ Condensed section, locally with iron oaids. Main regional hiatus Fig. 5. Chronostratigraphic correlation chart showing the fades distribution on the Aragonese and Castilian platfonllS. careous mudstones to wackestones, which can be ab­ sent or replaced by a basal reworked level, and an upper part consisting of calcareous gminstones to packstones. Other, locally developed, sequence types are filling sequences. Their lower parts consist of calcareous pack­ stones to wackestones that contain large bioclasts and reworked fossils, sometimes phosphatic and imbricated whereas their upper parts are made of calcareous wack­ estones to mudstones which can show ripple lamina­ tions. The thickness of the Moscardon Formation varies on the Central External Castilian P latfonn between 3 and 25 m (Fernimdez-L6pez, 1985), decreases towards its SE parts where it is represented by a few meters of calcareous wackestones to packstones containing cal­ careous ooids, and [mally pinches out near the Medi­ terranean coast. On the Aragonese Platform, the thickness of these bioclastic facies, containing crinoids and sponges, reaches 23 m in Ricla and 17 m in the Belchite sections (Sequeiros et aI., 1978; Fernandez­ L6pez and Aurell, 1988). Laterally the Moscardon Formation pinches out towards the southeast (about 2 m in the Obon-W section, Fig. 2) and is missing on the El Maestrazgo High. The Moscardon Formation commonly contains di­ verse and abWldant macro fossils indicative of open­ marine environments, such as ammonites, belemnites and sponges. Echinoderms, calcareous algae, bryozo­ ans, bivalves, bmchiopods, serpulids, and gastropods are also abundant. The unit is bounded by stratigraphic discontinuities. The oldest sediments correspond to the Bajocian Garantiana Zone, as seen in the Moscardon and in the Ricla sections. However, the lowest deposits of this unit can belong to the Bathonian Zigzag Zone, as in the Puebla de San Miguel section (Fernimdez-L6pez, 1985). The age of the top of this unit varies from the Bajocian Parkinsoni Zone up to the Bathonian Zigzag Zone (Fernandez-L6pez, 1985). The Moscardon Formation was deposited Wlder open-marine, normal salinity, high-energy and very shallow conditions providing for high carbonate pro­ duction and deposition rates during a brief episode. The External Castilian Platfonn was dominated by wave action and the progradation of high-energy facies over the low-energy, open-marine shallow facies of the El Pedregal Fonnation. On the Aragonese Platfonn, de­ velopment of the Moscardon Formation was condi­ tioned by the growth of sponge mud-moWlds, similar to those recorded on the Castilian Platfonn in the El Pedregal Fonnation. Towards the end of the Moscardon Formation the sea bottom relief of the external platform areas was largely infilled, giving rise to a brief phase of widespread shall owing of the Iberian platfonn system. 3.3. Domeno Formation The Domefio Formation is generally composed of well-stratified wackestones of micro filaments, locally packstones and mudstones, commonly with pellets, that are interbedded with marly limestones and calcareous marls. In the southeastern part of the External Castilian Platform, it contains mOWlds formed by volcanic rocks (Gautier, 1968, 1974). In some localities of the External Castilian and the Aragonese platfonns, lenticular bodies of grainstones, containing calcareous ooids, are overly­ ing the uppermost carbonates of the Moscardon Forma­ tion (e.g. Rambla del Salto, Aguaton, Obon-W and Andorra-l sections, respectively, Fig. 2). The Domefio Formation locally contains chert nodules, and Thalas­ sinoides and Zoophycos are common. In the Iberian Range, the top of the Middle Jurassic series is generally associated with ferruginous crusts and ferruginous ooids, fonnally defmed as the Anoyofrio Bed (G6mez and Goy, 1979), which marks a regional strati­ graphical gap. The Domefio Formation is organized into upward­ shallowing and -thickening sequences which are char­ acterized by a basal level that includes reworked fossils, an intermediate part of marly limestones, marls and limestones, and an upper part of limestones with irreg­ ular bedding that is capped by ferruginous crusts and borings. The Domefio Formation attains a thickness of 45 m at the type section and more in other outcrops of the SE External Castilian Platfonn (e.g. Chelva, Alcu­ bIas, Ribarroja and Sagunto sections, Fig. 2). In the Central External Castilian Platform, its thickness is usually smaller than a dozen meters. In the NW Exter­ nal Castilian Platform, its thickness is of the order of 100 m, where it constitutes the main sediments filling the Pozuel Depocentre. On the Aragonese Platfonn, there are expanded sections which surpass a thickness of 100 m (e.g. Ricla and Aguilon), and which grade into condensed sections thinner than 15 m, such as in the Andorra, La Caiiada de Verich, Barranco de las Estacas and Obon sections (Fig. 2, Sequeiros and Melendez, 1987; Aurell et aI., 1994). Open-marine bivalves, brachiopods, echinoderms, serpulids, ammonites, belemnites and gastropods are common. The base of the Domefio Formation is dia­ chronous at the zone scale, varying in age from the Bathonian Zigzag Zone (e.g. in the Domefio section) up to the Bathonian Progracilis Zone. The limestones with ferruginous ooids of this formation vary in age from Bathonian to Oxfordian. The upper Callovian Larnberti Zone and the lower Oxfordian Mariae Zone have so far not been identified. The top of the Domefio Formation, generally corresponds to the Arroyofrio Bed, which represents condensed sections (Figs. 3 and 5) and includes a hiatus of regional extent. The sediments of the Domefio Formation were de­ posited on an open-marine, normal salinity, external carbonate platform, the palaeogeographic configuration of which was varied during early Bathonian to middle Oxfordian times. During the Bathoruan and Callovian, the thermal subsidence of this external platform was overprinted by synsedimentary faulting controlling dif­ ferential subsidence of individual blocks (Salas et aI., 2001). During late Callovian and early Oxfordian, the External Castilian and Aragonese platforms became extremely shallow and uniform. The top of the Domefio Formation reflects a phase of widespread homogenisation and emersion of these platforms and is associated with a hiatus that is recorded in the entire studied area. 4. El Maestrazgo High During Middle Jurassic, the El Maestrazgo area formed a high that was flariked by the open-marine External Castilian, Aragonese and Tortosa platfOlTIls. This high was transected by a complex array of NW­ and NE-trending synsedimentary faults (Vinaros, Ateca, Castellon, Caudiel, Teruel, and Requena-Mora faults in Fig. 4), which delimited a series of tectonically active blocks (Canerot, 1974; Burrollet and Winnock, 1977; Cadillac et aI., 1981; Canerot et aI., 1985a,b; Ferruindez-Lopez et aI., 1996, 1998; Gomez and Fer­ mindez-Lopez, 2004a,b). On the El Maestrazgo High, restricted marine, commonly dolomitic carbonates, fonning 20--40 m thick condensed sections, were deposited. However, oil wells drilled in this area indicate that on some subsiding fault blocks up to 100-250 m thick ex­ panded dolomitic sections were deposited, thus form­ ing the so-called El Maestrazgo Depocentre (Fig. 4). The Rafales Formation (G6mez and Fernimdez­ Lopez, 2004a,b) includes the restricted carbonate fa­ cies, and the transition between internal and external facies, that are associated with the El Maestrazgo High. 4.1. Ra/ales Formation The Rafales Formation is generally composed of massive, crystalline dolomitic limestones. These pass laterally into higher energy facies consisting of bio­ clastic grainstones to packstones with calcareous ooids (e.g. in the Ejulve sections), as well as into calcareous mudstones containing rare macro fossils (Barranco de las Ermitas and Adzaneta sections). Bioturbation tex­ tures and structures and bioclastic rills are common. The most common sequences are upward-thickening and -shallowing, showing hardgrounds with borings that can be filled with ferruginous crusts and glauco­ nite. In some areas where dolomitization does not affect the whole Middle Jurassic sequence (e.g. in the Rafales section), the restricted facies of the Rafales Formation grade into the open-marine bioclastic wack­ estones of the Domefio Formation that contains ammonites. The Wlit reaches a thickness of 26 m in the Rafales section, where the lower contact is fault­ controlled, and about 25 m in the Barranco de las Ermitas and in the Adzaneta sections (Canerot et aI., 1985b). These condensed sections pass latemlly into 100-250 m thick dolomitic sections, identified in oil wells (Bobalar-1 and 2, Maestrazgo-2 and Salsadella-1 wells in Fig. 2; Lanaja, 1987; Ferruindez-Lopez et aI., 1996, 1998). In areas where this Wlit is not dolomitized, remains of benthic organisms, such as bivalves, echi­ noids, calcareous algae, sponges, bryozoans, brachio­ pods and gastropods, are common. In contrast, remains of nektic organisms, such as ammonites and belemnites, indicative of open-marine conditions, are very rare or absent. However, in the lowermost part of the Rafales section (Fig. 2), the occurrence of sonninids and stephanoceratids indicates an early Bajocian age, whilst in its upper part parkinsonids suggest a late Bajocian age. At the transition between restricted and open-marine facies, as seen in the upper part of the Rafales Formation type section, this Wlit is covered by the ammonite-bearing carbo­ nates of the Domefio Formation, that permit to iden­ tify Bathonian and Callovian zones. The Rafales Formation was deposited in a restricted shallow-ma­ rine environment that was characterized by intense production and accumulation of carbonates. Bars and channel belts chamcterize high-energy facies, whereas low-energy facies are represented by dolostones with local muddy limestones. 5. Tortosa Platform On the Tortosa Platform, expanded Middle Jurassic sections surpassing 350 m in thickness are composed of open-marine external platform facies and testify to its rapid subsidence (Fig. 6; Fernimdez-Lopez et aI., 1996, 1998; Gomez and Fernimdez-Lopez, 2004b). Although thickening- and shallowing-upward sequences predom­ inate, some deepening sequences occur locally during Aragonese Platform Andorra Alcorisa Colcndo Andorra • � Oolitic cnd bioclostic pockstcne l:....:......!J to groinstone V:.�:/?l Microfi ' oment wockeslone �:: :::-:::-:.:.:::� Alternating morl :::=:::=::: and limestone .j-/ / Salou-Tivissa �'6/ ,' Block �/ ,( Colondo ��'&'*;' \ � . Solo f:-'li/