Eastern Iberian Chain Research Articles

Salt tectonics vs. inversion tectonics: The anticlines of the western Maestrazgo revisited (eastern Iberian Chain, Spain)

AbstractMany works in the last decades underline the role of evaporites, not just as a conditioning factor but as the engine for subsidence and eventually basin inversion. The western Mediterranean alpine ranges are being investigated in this regard because of the presence of discontinuous units of Permian to Triassic evaporites, deposited in the western Tethys basins. This work presents a thorough analysis of two particular structures (Cañada Vellida and Miravete anticlines) in the intraplate Maestrazgo basin (eastern Iberian Chain, Spain) in which evidence to support their reinterpretation as salt‐driven structures have been recently reported. Our analysis includes (i) a comprehensive stratigraphic and structural study of the folds along their entire trace, (ii) the compilation of thickness and distribution of evaporite–bearing and supraevaporite units, paying special attention to changes in the thickness of units in relation to anticlines, and (iii) the study of fault patterns, sometimes in relation to the mechanical stratigraphy. All three aspects are also documented and discussed on a regional scale. The new data and interpretations reported here reinforce the extensional origin of the Late Jurassic–Early Cretaceous basins, and the role of regional extensional tectonics as the responsible for the development of first‐order syn‐sedimentary normal fault zones driving the formation and evolution of sub‐basins. These basins were subsequently inverted and deformed, including the formation of complex, box‐geometry anticlines that, in their turn, controlled deposition in Cenozoic basins. The review of the arguments that support the alternative of salt tectonics for the origin of such anticlines has allowed us to delve into the sedimentary and tectonic evolution of the inverted extensional basins and to propose a specific model for the development of these faulted anticlines. The role of salt levels and other interlayered detachments in the structuring of sedimentary basins and their inversion is also pondered. The observations in the eastern Iberian Chain reported here have implications to assess ongoing reinterpretations in terms of salt tectonics in other alpine basins and ranges of the western Mediterranean.

The ancestry of the Rhenish Middle Siegenian brachiopod fauna in the Iberian Chains and its palaeozoogeography (Early Devonian)

At Nigüella (Eastern Iberian Chain), a spatially restricted brachiopod fauna is slightly older than the traditional Middle Siegenian. It is composed of taxa most of which invaded the Rhenohercynicum shortly later, when facies there changed from deltaic to shallow marine. Occurring in typically Rhenish lithofacies, the Nigüella fauna lacks the taxa that are most common in coeval faunas of lbero-Armorica, but its own taxa have earlier Ibero-­Armorican ancestors and origins, except Multispirifer cf. solitarius and Arbizustrophia n. sp. N. Hitherto, M. solitarius seemed to be an endemic of the Rhenohercynicum; Arbizustrophia was known from the Late Emsian of Asturias; the ancestors of both are unknown in Ibero-Armorica, which suggests viable zoogeographic connections with unknown further regions. Contrary to current opinions, in the late Silurian and early Early Devonian, Ibero-Armorica and Rhenohercynicum do have common taxa, and faunal differences are largely due to facies, especially deltaic facies in the Rhenohercynicum during 7 Ma of late Lochkovian and Pragian time. Effective oceanic faunal barriers lacked. Contradictory plate tectonic scenarios, which had been founded initially on defective faunistic concepts and supposed subduction of various broad oceans, are revised according to faunistic criteria and turn out to be unwarranted also in other aspects. The meanings of the traditional Siegenian substages are elucidated, whereas the actual standard stages cannot be applied to the interval concerned.

Barremian charophytes from the Maestrat Basin (Iberian Chain)

A lower and upper Barremian 690 m-thick succession composed of freshwater and brackish limestones, marls and clays was measured and sampled in the Maestrat Basin, Eastern Iberian Chain (Castelló, Spain). Thirty-three taxa were identified from charophyte fructifications and thalli, belonging to the three families that coexisted during the Early Cretaceous, i.e. Porocharaceae, Characeae and Clavatoraceae. Up to 25 different Clavatoraceae utricles were identified. This high species richness of clavatoraceans has not been observed elsewhere and sheds light on the role of Iberia, and particularly the Maestrat Basin, as a diversity hotspot for this family during the Barremian. Several of them have been taxonomically revisited, as regards both utricles and thalli. The Echinochara lazarii utricle is reinterpreted as showing bilateral rather than triradial symmetry. Anagenetic evolution within Clavator calcitrapus has been documented and has enabled us to distinguish between two varieties linked by intermediate morphotypes of biostratigraphic and palaeobiogeographic interest. The taxon Clavator grovesii var. jiuquanensis is reported for the first time in the Iberian Chain and in Spain. The structure of Charaxis spicatus is revisited and a new type of cortication is defined, called the double triplostichous cortication, which is unknown in either fossil or extant charophytes. This thallus is found in anatomical connection with Echinochara lazarii utricles, enabling a whole-plant reconstruction of the Echinochara plant. Lastly, new characters were found in Munieria grambastii thalli that confirm the membership of genus Munieria to the clavatoracean charophytes, particularly the calcification pattern of the internodal cell, which recalls that of clavatoroid utricles.

Tectogonotoechia rivasi n. sp. A new lower Pragian Celtiberian (Spain) Ancystrorhynchoidea rhynchonellid brachiopod

A new lower Pragian Ancystrorhynchoidea rhynchonellid, Tectogonotoechia rivasi n. sp. of the Celtiberian region (Eastern Iberian Chain, EIC, and Eastern Guadarrama, EG) is described and figured. The growth of the new species, from the last neanic stage to the senescent one is specially underlined. T. rivasi n. sp. is characterized as the other species of the genus by the occurrence of a pseudoseptum and a pseudoseptalium in the dorsal interior, with a fine connectivum forming a roofed over structure covering most part of the latter. Exteriorly, the species is an entirely costate, strongly dorsibiconvex, uniplicate form lacking of marginal spines. T. rivasi n. sp. is fairly abundant in the upper part of the Nogueras Formation in the EIC and in the lower third of the Cercadillo Formation in the EG and it is usually accompanied by a varied macrofauna of brachiopods, bryozoans, solitary corals, tabulates, trilobites, ostracods and others. The biocenose of T. rivasi n. sp. is characterized by the occurrence of abundant incrusting and boring epizoans colonizing mainly the brachiopods, representing different symbiotic interactions and probably a permanent risk for the epizoans to be buried in an unstable soft substrate.

Middle-Upper Triassic stratigraphy and structure in the Alt Palància region (eastern Iberian Chain): A multidisciplinary approach

The present study provides new data of the Middle-Upper Triassic successions and their deformation in the eastern Iberian Chain, where contractional tectonics during the Cenozoic disrupted this Mediterranean type of Triassic rocks. The succession, divided into three Muschelkalk units, was studied in the Alt Palància area. In this area, both the lower and upper Muschelkalk consist of two main types of sub-units, those made up of carbonate and those of carbonate-marl alternation. The marked similarity observed between the evaporite units of the middle Muschelkalk and the Keuper humpers their unambiguous discrimination in the field. The integration of geological mapping, stratigraphic logging, palynological dating and gypsum isotope analysis carried out provided that: i) a change in the structural style, facies, and depositional thickness occurs across a SW to NE transect at both sides of the Espina-Espadà Fault, providing evidence for the extensional activity of this major structure; ii) palynological data assign Anisian age to the Röt facies and the lower and the middle Muschelkalk units, and Ladinian to the upper Muschelkalk unit; iii) the δ34SCDT and δ18OSMOW values of gypsum reveal as a useful proxy to discriminate between the middle Muschelkalk (δ34S: 15.6 to 17.8‰) and the Keuper (δ34S: 14 to 15.5‰) units; and iv) the isotopic signature also helps to identify clayey-marly gypsiferous outcrops made up of the two evaporite facies due to tectonic juxtaposition. These results confirm the Mediterranean type of Triassic rocks for the entire Alt Palància and other areas to the NE. This multidisciplinary approach reveals as a robust methodology to study Triassic basins in Iberia and to other geological domains where the carbonate-evaporite successions have been greatly disrupted by tectonism.

Lower Aptian ammonite and carbon isotope stratigraphy in the eastern Prebetic Domain (Betic Cordillera, southeastern Spain)

Major global palaeobiologic and palaeoenvironmental changes occurred during the Early Aptian. Precise dating and timing of the different events is crucial to determine possible cause-effect relationships between them. In this regard, the combination of biostratigraphic and chemostratigraphic data can provide a very useful tool for time control. So far attempts to correlate the Lower Aptian carbon isotope record and the ammonite zonation yielded contradictory conclusions. In this paper, we present the results of an integrated analysis of the ammonite stratigraphic distribution and highresolution carbon isotope profiles from Lower Aptian sections of the eastern Prebetic Domain (Betic Cordillera, southeastern Spain). We recognized, in ascending order, the Deshayesites oglanlensis, Deshayesites forbesi, Deshayesites deshayesi, and Dufrenoyia furcata Zones. This succession is the same as that recently identified in the eastern Iberian Chain, and it closely correlates with both standard Mediterranean and Boreal zonations. The carbon isotope record displays the trends globally recognized for the Early Aptian, with two long positive shifts separated by a pronounced negative excursion. Calibration of this isotopic record with the ammonite zonation shows that the age of OAE 1a, which corresponds to the negative excursion and subsequent positive shift, is constrained to the middle/upper part of the Deshayesites forbesi Zone.

Xerticeras gen. nov., a new genus of micromorphic heteromorph ammonite (Ancyloceratina, Ancyloceratidae) from the lower Aptian of Spain

Biostratigraphical and paleontological studies of lower Aptian material from the Eastern Iberian Chain (Spain) have revealed the presence of a new genus of micromorphic heteromorph ammonite: Xerticeras gen. nov. (type species: Xerticeras salasi sp. nov.). This new taxon comes from the Deshayesites deshayesi and Dufrenoya furcata ammonite zones. The size difference observed in the population is considered due to sexual dimorphism.

Lower Aptian ammonite biostratigraphy in the Maestrat Basin (Eastern Iberian Chain, Eastern Spain). A Tethyan transgressive record enhanced by synrift subsidence

The present paper analyses the stratigraphic distribution of ammonites collected in the Lower Aptian sediments of the Maestrat Basin (E Spain). The faunal successions obtained from the systematic sampling of ten selected sections located in several sub basins led us to identify four biostratigraphic units (from base to top: Deshayesites oglanlensis, Deshayesites forbesi, Deshayesites deshayesi and Dufrenoyia furcata Zones) that are directly correlatable with the current Mediterranean standard zonation. This study further provides essential biochronologic information to accurately date the different lithostratigraphic units included in the interval studied. Thus, the upper part of the Xert Formation can be tentatively attributed to the lowermost Aptian (D. oglanlensis Zone). The Forcall Formation, which has yielded most of the ammonites, practically extends within most of the Lower Aptian. Its lower and middle parts (Cap de Vinyet and Barra de Morella Members) correspond to the upper part of the D. oglanlensis Zone and the lower part of the D. forbesi Zone, respectively. The base of the Morella la Vella Member (upper part of the Forcall Formation) includes the local record of Oceanic Anoxic Event 1a (OAE 1a) and correlates with the Roloboceras hambrovi horizon (middle/upper part of the D. forbesi Zone). The boundary between the Forcall Formation and the Villarroya de los Pinares Formation is diachronous and varies depending on the sub-basins. The base of the Villarroya de los Pinares Formation can be dated as the middle-upper part of the D. furcata Zone in the Galve, Perello and Salzedella sub-basins.

Sedimentary evolution of an Aptian syn-rift carbonate system (Maestrat Basin, E Spain): effects of accommodation and environmental change

We report an integrated study of an expanded and relatively complete syn-rift continental to epeiric marine succession of Aptian age, cropping out in the western Maestrat Basin (eastern Iberian Chain). Four transgressiveregressive sequences are recognized throughout this mixed carbonate-siliciclastic succession, with excellent age control provided by ammonite biostratigraphic data. The transgressive systems tracts consist mainly of alternations of marls and limestones rich in orbitolinids. The regressive systems tracts are essentially characterized by wave- and tidally influenced siliciclastic and carbonate deposits, and by the development of carbonate platforms with rudists, corals, orbitolinids and green algae. Carbon and oxygen isotope curves were established in order to identify the global d13C perturbations related to the Early Aptian Oceanic Anoxic Event (OAE1a). These perturbations commence with a horizon of coral rubble encrusted by Lithocodium aggregatum and Bacinella irregularis with widespread large-sized discoidal Palorbitolina lenticularis. Associated d18O values indicate high-frequency cooling-warming climatic cycles. The fault-controlled rapid syn-rift subsidence recorded during this stage was the most important factor in producing accommodation. However, the major transgressions, sea level falls and biotic changes recorded in the eastern Iberian Chain are in agreement with those registered in other contemporaneous basins of the Tethys. Thus, the resulting sedimentary succession faithfully reflects the major oceanographic and climatically-driven global changes that characterized this stage albeit within a context established by regional tectonics. Hence, this well-documented record of the evolution of an Aptian epicontinental sea provides a useful comparative case study for the analysis of other Aptian epeiric sedimentary successions.

Paleoseismological analysis of an intraplate extensional structure: the Concud fault (Iberian Chain, eastern Spain)

The Concud fault is a 13.5 km long, NW–SE striking normal fault at the eastern Iberian Chain. Its recent (Late Pleistocene) slip history is characterized from mapping and trench analysis and discussed in the context of the accretion/incision history of the Alfambra River. The fault has been active since Late Pliocene times, with slip rates ranging from 0.07 to 0.33 mm/year that are consistent with its present-day geomorphologic expression. The most likely empirical correlation suggests that the associated paleoseisms have potential magnitudes close to 6.8, coseismic displacements of 2.0 m, and recurrence intervals from 6.1 to 28.9 ka. At least six paleoseismic events have been identified between 113 and 32 ka. The first three events (U to W) involved displacement along the major fault plane. The last three events (X to Z) encompassed downthrow and hanging-wall synthetic bending prompting fissure opening. This change is accompanied by a decrease in slip rate (from 0.63 to 0.08–0.17 mm/year) and has been attributed to activation of a synthetic blind fault at the hanging wall. The average coseismic displacement (1.9–2.0 m) and recurrence period (6.7–7.9 ka) inferred from this paleoseismic succession are within the ranges predicted from empirical correlation. Such paleoseismic activity contrasts with the moderate present-day seismicity of the area (maximum instrumental Mb = 4.4), which can be explained by the long recurrence interval that characterizes intraplate regions.

New Lower Kimmeridgian Ataxioceratin Ammonite from the Eastern Iberian Chain, Spain: Systematic, Biogeographic, and Biostratigraphic Relevance

New ammonites collected bed-by-bed from the upper part of Ataxioceras hypselocyclum Chronozone deposits in the eastern Iberian Chain are described as Geyericeras gen. nov. The new genus includes micro- and macroconchiate Ataxioceratinae of small size, with moderate to loose coiling and subpolyplocoid ribs, a character crucial for its identification. Key points for the comparative identification of Geyericeras gen. nov. are: (i) microconchiate Geyericeras show morphological convergence with evolute specimens of the stratigraphically older genus Schneidia [m]; (ii) contemporary Ataxioceratinae genera such as Ardescia [m, M] and Lithacosphinctes [m, M] did not develop subpolyplocoid ribbing; (iii) smoothing of sculpture combined with short primary ribs are not realized in Geyericeras gen. nov. [M] and can be therefore used to separate the new genus from Ataxioceras [M]; and (iv) smaller shells, and weaker and less dense ribbing with no parabolic structures differentiate Geyericeras gen. nov. [m, M] from Para...

The upper Katian (Ordovician) bryozoans from the Eastern Iberian Chain (NE Spain)

The upper Katian (Ordovician) bryozoans from the Eastern Iberian Chain (NE Spain)

Biostratigraphic characterization by means of ammonoids of the lower Aptian Oceanic Anoxic Event (OAE 1a) in the eastern Iberian Chain (Maestrat Basin, eastern Spain)

It is now generally accepted that the Oceanic Anoxic Event 1a [OAE 1a] correlates with the lower part of the Leupoldina cabri planktonic foraminiferal Zone. Its calibration against the standard ammonite scale, however, seems to be more problematic. This is due, in part, to the fact that ammonites are scarce and/or of little diagnostic value from a biochronological viewpoint in the lower Aptian pelagic successions where the black shale horizons are better developed. We have been able to characterize OAE 1a geochemically in the relatively shallow water deposits of the eastern Iberian Chain (Maestrat Basin, eastern Spain), where ammonite faunas are rich. The interval corresponding to this event is dominated by the genera Roloboceras and Megatyloceras, accompanied by Deshayesites forbesi and Deshayesites gr. euglyphus/spathi. This assemblage is characteristic of the middle/upper part of the Deshayesites weissi Zone. The first occurrence of the species Deshayesites deshayesi (d'Orbigny), which marks the base of the overlying zone, takes place in our sections some metres above the OAE 1a interval. In the historical stratotype region of Cassis-La Bédoule (southern Provence Basin, southeastern France), the OAE 1a interval is also characterized by the presence of Roloboceras and Megatyloceras. Nevertheless, it has usually been correlated with the D. deshayesi Zone. In our opinion, this discrepancy is due to divergences in the taxonomic assignments of the deshayesitids present in these beds. In fact, the specimens attributed by French authors [Ropolo, P., Conte, G., Gonnet, R., Masse, J.P., Moullade, M., 2000. Les faunes d'Ammonites du Barrémien supérieur/Aptien inférieur (Bédoulien) dans la région stratotypique de Cassis-La Bédoule (SE France): état des connaissances et propositions pour une zonation par Ammonites du Bédoulien-type. Géologie Méditerranéenne 25, 167–175; Ropolo, P., Moullade, M., Gonnet, R., Conte, G., Tronchetti, G., 2006. The Deshayesitidae Stoyanov, 1949 (Ammonoidea) of the Aptian historical stratotype region at Cassis-La Bédoule (SE France), Carnets de Géologie / Notebooks on Geology Memoir 2006/01, 1–46.] to D. deshayesi and D. dechyi can be reinterpreted as belonging to D. forbesi. Following this reinterpretation, the Roloboceras beds (equivalent of OAE 1a) of Cassis-La Bédoule would also correspond to the D. weissi Zone. This age is additionally corroborated by data from southern England [Casey, R., 1961a. The stratigraphical palaeontology of the Lower Greensand. Palaeontology 3, 487–621; Casey, R., 1961b. A Monograph of the Ammonoidea of the Lower Greensand, part III. Palaeontographical Society, London, pp. 119–216], and by our recent observations in Le Teil (Ardèche Platform, southeastern France), where the Roloboceras faunas are also associated with Deshayesites consobrinus and Deshayesites gr. euglyphus, taxa that are characteristic of the D. weissi Zone.

Charophyte-rich microfacies in the Barremian of the Eastern Iberian Chain (Spain)

Non-marine carbonate microfacies based on charophytes are a useful palaeoenvironmental tool that has been poorly developed to date. In the Barremian of the Maestrat Basin (Eastern Iberian Chain), five such microfacies are described and interpreted in terms of sedimentology and palaeoecology: (1) Microfacies of clavatoracean remains are mudstones and wackestones rich in utricles and well-preserved charophyte thalli of the genus Clavatoraxis, representing in situ deposition of clavatoracean meadows. (2) Microfacies of filamentous algae and clavatoraceans are mudstones with a high proportion of calcified filaments attributed to cyanobacteria and green algae. This facies may correspond to the open lake benthos. (3) Microfacies of Intraclasts and Charophyte remains are packstones formed on the shores of freshwater lakes or brackish swamps that underwent subaerial desiccation and wave reworking. (4) Microfacies of Porocharacean remains are wackestones and packstones with abundant gyrogonite fragments of genus Porochara. They are related to the reworking of a porocharacean meadow in shallow brackish marshes. (5) Microfacies of Munieria grambasti Bystricky 1976 fragments are grainstones attributed to the reworking of Munieria-dominated meadows. In consequence to these results, a palaeoecological model based on charophyte remains is proposed as a useful tool in carbonate facies analysis.

Tectonically driven fluid flow and associated low-grade metamorphism during the Alpine compression in the eastern Iberian Chain (Spain)

Fluid inclusions and clay mineralogy of the Permo-Triassic rocks from the Espina and Espadà Ranges (SE Iberian Chain, Spain) have been investigated to establish their relationship with hydrothermal fluid circulation during the Alpine Orogeny. Primary fluid inclusions in quartz-filled tension gashes in Permo-Triassic sandstones reveal maximum temperatures around 230 °C and very constant salinities of 8.5% wt. eq. NaCl. Secondary fluid inclusions found in quartz from the Santonian Ba–Cu–Hg deposits show similar compositional and thermodynamic characteristics, denoting an Alpine recrystallization. Clay mineral composition of Permo-Triassic mudrocks is characterized by pyrophyillite, indicating low-grade metamorphic conditions. Field observations and experimental data suggest that the crystallization of quartz in tension gashes, the formation of secondary fluid inclusions and the development of the metamorphism are contemporaneous and related to fluid circulation during the Alpine compression. Fluid flow took place along the Hercynian fault system that was reactivated during the Mesozoic rift stage and inverted during the Alpine deformation.

Superposed buckle folding in the eastern Iberian Chain, Spain

The Aliaga area (eastern Iberian Chain) shows large-scale examples of buckle superposition developed during Tertiary folding. In most cases, ENE-trending folds overprint earlier NNW–SSE-trending ones. The resulting structures are mapped, analysed, and genetically classified by comparison with analogue models described by several authors. The following types are found: standard Type 1 (1a: dome-and-basin structure, 1b: unequal-wavelength overprinted folds); modified Type 1 (1c: T-shaped ‘joined’ folds; 1d: T-shaped ‘abutting’ folds; 1e: L-shaped folds; 1f: ‘snake-like’ folds); standard Type 2 (2a: non-cylindrical buckling of earlier axial surfaces involving hinge replacement). Different superposed sets of flexural-slip striations record successive folding episodes in snake-like folds, and hinge replacement in the case of Type 2a superpositions. Types 1 and 2 apparently develop where the earlier folds have interlimb angles over and below 90°, respectively, which fits the results of analogue modelling and theoretical analysis by previous authors. Types 1b and 1d are associated with higher W1/W2 wavelength ratios than Types 1a and 1c. Other controlling factors are viscosity contrast and erosion processes. Specifically, erosion of competent limestone beds in the hinge zone of a NNW–SSE-trending anticline allowed the near-vertical eastern limb to be refolded into snake-like folds.

The significance of tectonic-related tertiary remagnetization along the margins of the Valencia trough

The paleomagnetic data from the margins of the Valencia Trough are derived from Mesozoic and Tertiary rocks from the Balearic Islands, Catalan Coastal Ranges and Eastern Iberian Chain. These rocks are affected by a complex structural evolution consisting of an initial compressive stage followed by one of extension. Cenozoic paleomagnetic data indicate that rotations occurred during the Paleogene compression and before the extension started (Lower Miocene) in the Catalan Coastal Ranges. In contrast, in the Balearic Islands the rotations are synchronous to both compressional (Late Oligocene-Middle Miocene) and extensional tectonics (post-Middle Miocene). In both areas the Mesozoic limestones are remagnetized. In the Catalan Coastal Ranges they display the same direction as the Paleogene syn-compressive deposits whereas in the Balearic Islands they conform with Lower Miocene (Burdigalian) syncompressive rocks. It is concluded that the processes of remagnetization that affected eastern Iberia are related to a compressive rather than an extensional tectonics regime

Facturación a distintas escalas y campos de esfuerzos durante la tectogenesis alpina en el área de Mosqueruela (Teruel)

The analysis of the brittle tectonic deformation on all scales in one area of the eastern Iberian Chain (Mosqueruela, Teruel) allows us to define a fracture pattern characterized by three main sets: NNE to NE, ENE and E to ESE. Brittle structures (stylolites, tension gashes, brittle-ductile shear zones and faults) show a poliphase Alpine tectonics. From the analysis of fault populations two compressive (wrench regime) phases and a multidirectional extension regime have been inferred. Their chronological evolution is the fol1owing: 1) ENE compression; 2) ESE compression; 3) nearly multidirectional NNE extension. The study of fractures using a number of methodologies at macro-, meso- and microstructural scales allows us to suggest a model of stress distribution and relationships between different structures in sorne areas. The detailed fracture mapping on a hectometric scale shows the distribution and strike variations of fractures. These changes have been interpreted as stress deflection phenomena due to major structures which, in many cases, were identified. Examples of stress deflections have been analyzed both for strike-slip and normal fault sets.

Mesozoic extensional tectonics in the southeast Iberian Chain

AbstractThe Desert de les Palmes area, in the southeast Iberian Chain, belongs to a Mesozoic NE–SW high which separated the early Cretaceous basins of the Maestrat and Aliaga-Penyagolosa from the little Orpesa basin. Its structure is characterized by the development of a system of NE–SW to ENE–WSW extensional listric faults detached in a shallow upper crustal level (1.7–2.2 km), mostly affecting the pre-Upper Cretaceous rocks. These faults record two well-differentiated rifting periods: (1) a first late Triassic–early Jurassic rifting period that divided the Desert de les Palmes high in several blocks; (2) a second early Cretaceous rifting period, only developed in the eastern margin of the Desert de les Palmes high, which was related to the opening of the Maestrat, Aliaga-Penyagolosa and Orpesa basins. Based on the comparison of the main features of this Mesozoic structure with an analysis of the structural and subsidence data already known in the neighbouring Mesozoic basins (Maestrat, Aliaga-Penyagolosa and Columbrets), a geodynamic scenario for the crustal evolution of the eastern Iberian Chain is also suggested. This involves four evolutionary stages: (1) Triassic rift (late Permian–Hettangian); (2) early and middle Jurassic postrift (Sinemurian–Oxfordian); (3) late Jurassic and early Cretaceous rift (Kimmeridgian–middle Albian), which includes a short Hauterivian postrift period; and (4) late Cretaceous postrift (late Albian–Maastrichtian).

Découverte d'une microfloretournaisienne dans la Chaine Ibérique orientale (Espagne)

In the core of the Montalban Anticline, in the province of Teruel (Spain), the Palaeozoic basement of the eastern Iberian Chain is known to be Devonian as a result of conodont and ostracod data. Complementary data through palynology have shown the presence of early to middle Tournaisian as well as twenty four species of miospores and twelve species of acritarchs have been recognised, e.g. Spelaeotriletes, Vallatisporites, Leiotriletes struniensis and Dibolisporites distinctus. As the Lower Carboniferous is documented for the first time in this area, the evidence of the Carboniferous deposits unconformity upon underlying Devonian layers can't be discussed, but the gap between the Carboniferous and the Devonian layers must be reappraised.