Taphonomy of fossil macro-invertebrate assemblages as a tool for ecostratigraphic interpretation in Upper Jurassic shelf deposits (Prebetic Zone, southern Spain)

Composition and taphonomy of macro-invertebrate fossil assemblages, together with facies analysis, have been approached in order to interpret shifting paleoenvironmental conditions in the External Prebetic (S-SE Spain) during the early Late Jurassic (Middle Oxfordian). In oolitic and spongiolitic limestones, the size of fossil remains, mode of preservation, within-bed position, corrasion, fragmentation, epibiont and biogenic encrustation, disarticulation and uncoupling, allow recognition of two taphofacies, respectively. Identified ecostratigraphic events and trends accord with rapid flooding under high-energy conditions related to ecospace enlargement for cephalopods and then the persistence of lower energy, long-lasting exposure of skeletals and higher sedimentary rates. The paleoenvironmental interpretation is consistent with neritic environments shifting from shallow carbonate to hemipelagic sedimentation and enlarging of shelf ecospace for marine invertebrates.     

Microbial encrustations from the Middle Oxfordian-earliest Kimmeridgian lithofacies in the Prebetic Zone (Betic Cordillera, southern Spain): characterization, distribution and controlling factors

Two main types of microbial encrustation were identified in Middle Oxfordian to lowermost Kimmeridgian deposits in the Prebetic Zone (southern Spain), showing existing relationships between skeletal content, fabric and morphology of these organosedimentary structures. Laminated planar and concentric encrustations relate to peloidal fabrics (mainly constituted of microbes = microbial laminated fabrics s. str. and microbial oncoids s. str.), as well as to dense microbial fabrics periodically colonized by encrusting foraminifera (microbial laminated fabrics with nubeculariids and microbial oncoids with nubeculariids). Sedimentation rates, substrate stability and grain size, as well as illumination, influenced microbial growth pattern as major controlling factors in low-energy conditions, and forced palaeogeographic and stratigraphic patterns of distribution. Significant encrustation was identified in terrigenous-poor lithofacies from the middle (Transversarium-Bifurcatus zones) to the outer (Transversarium-Bimammatum zones) shelf in the Prebetic Zone. Rare-to-absent encrustation characterized terrigenous-rich deposits (Bimammatum and Planula zones) in the area.     

Benthic foraminiferal morphogroups of mid to outer shelf environments of the Late Jurassic (Prebetic Zone, southern Spain): Characterization of biofacies and environmental significance

Benthic foraminiferal assemblages belonging to a mixed carbonate–siliciclastic shelf succession of the Oxfordian (Upper Jurassic) in the Prebetic, southern Spain, were analyzed. The faunal data, obtained on thin sections of strongly lithified sediments, allowed the detailed differentiation of a foraminiferal morphogroups system to be applied to the interpretation of paleoenvironmental conditions. Eleven morphogroups were differentiated according to shell composition, general morphology, number of chambers and mode of coiling. Paleoenvironmental analysis combines these features with inferred life-style (epifaunal, shallow infaunal and deep infaunal) and feeding strategy (suspension-feeder, deposit-feeder, herbivores, etc.) of the foraminifera. Analogies and differences regarding previously established morphogroup systems could be outlined accordingly.

In the Prebetic Oxfordian, distribution trends of foraminiferal morphogroups allow for a comparison of mid to outer shelf environments occupying the South-Iberian paleomargin, indicating that nutrient supply was the most important factor controlling morphogroup development. The mid shelf settings are dominated by epifaunal active herbivores–phytodetritivores, in shallow to deep substrate position of the redox boundary. The outer shelf is dominated by agglutinated and infaunal detritivore-bacterial scavenger morphogroups revealing a deep substrate position of the redox boundary. Particularly favorable trophic conditions in mid shelf environments are related with higher phytodetritus input from more proximal and shallower shelf areas.     

Stratigraphy of Palaeocene phosphate pelagic stromatolites (Prebetic Zone, SE Spain)

The hemipelagic domain of the ancient southern continental margin of Iberia is home to a strongly condensed pelagic succession (6–15 cm thick) characterized by the presence of phosphate stromatolites. This succession, probably generated in the slope of the continental margin, records a period of some 9 Ma, corresponding to the latest Maastrichtian to Late Thanetian interval. A microstratigraphical analysis allows for characterizing and biostratigraphically dating six successive developmental stages in the succession, which outline the main environmental evolution of the depositional setting. The first of them determined the generation of a submarine hardground during the latest Maastrichtian to earliest Danian interval. The other five are represented by five successive microstratigraphical, unconformity-bounded, genetic units, respectively Early–Middle Danian, Late Danian–Early Selandian, intra-Selandian, Late Selandian–Early Thanetian, and Middle–?Late Thanetian in age. The three oldest units are characterized by the accretion of phosphate stromatolites, favoured by very low rates of pelagic sedimentation and by a microbially mediated extra input of phosphate. The two youngest units are dominated by carbonate deposition, which has always taken place at very low rates. Condensed sedimentation was abruptly interrupted at the end of the Palaeocene (?latest Thanetian), when the condensed succession and its hosting substrate were gravitationally slumped and re-deposited at the base of the slope in the form of a mega-debris flow that can be now observed in Sierra de Aixorta (Alicante, SE Spain). The Aixorta pelagic phosphatic stromatolites are among the youngest ever described, and their existence suggests that the oceanographic conditions necessary for their development prevailed during most of the Palaeocene, but disappeared during the Late Selandian, never to return.     

Oncoid growth and distribution controlled by sea-level fluctuations and climate (Late Oxfordian,Swiss Jura Mountains)

Abundant lagoonal oncoids occur in the Late Oxfordian Hauptmumienbank Member of the Swiss Jura Mountains. Four oncoid types are observed in the studied sections and classified according to the oncoid surface morphology, the structure and composition of the cortex, and the texture and fauna of the encasing sediment. Micrite-dominated oncoids (types 1 and 2) have a smooth surface. Type 1 has a rather homogeneous cortex and occurs in moderate-energy environments. Type 2 presents continuous or discontinuous micritic laminae. It is associated with a low-diversity fauna and occurs in high-energy facies. Bacinella and Lithocodium oncoids (types 3 and 4) display a lobate surface. They are dominated by microencrusters (Bacinella irregularis and Lithocodium aggregatum) and are found in low-energy facies. The stratigraphic and spatial distribution of these oncoid types shows a correlation with the sequence-stratigraphic evolution of the studied interval, and thus with relative sea-level fluctuations. It can be shown that these sea-level fluctuations were controlled by orbital cycles with 100- and 20-kyr periodicities. At the scale of 100- and 20-kyr sequences, types 1 and 2 oncoids are preferentially found around sequence boundaries and in transgressive deposits, while types 3 and 4 oncoids are preferentially found around maximum floodings and in highstand deposits. This implies that changes of water energy and water depth were direct controlling factors. Discrepancies in oncoid distribution point to additional controlling factors. Platform morphology defines the distribution and type of the lagoon where the oncoids flourished. A low accumulation rate is required for oncoid growth. Additionally, humidity changes in the hinterland act on the terrigenous influx, which modifies water transparency and trophic level and thus plays a role in the biotic composition and diversity in the oncoid cortex.     

The Upper Cretaceous belemnite <Emphasis Type="Italic">Praeactinocamax plenus</Emphasis> (Blainville, 1827) from Lower Saxony (Upper Cenomanian,northwest Germany) and its distribution pattern in Europe

Occurrences of the Upper Cenomanian (Upper Cretaceous) belemnite Praeactinocamax plenus from the plenus Bed of northwest Germany (Söhlde-Loges working quarry near Salzgitter, Lower Saxony) are documented and described for the first time on the basis of two in situ finds. The find horizon and its surrounding beds are re-evaluated in a sequence stratigraphical context. In contrast to the interpretations of other authors, the plenus Bed is seen as a pelagization event in a parasequence of transgressively stacked beds, delimited by two significant erosion surfaces below and above. The exclusive occurrence of P. plenus in the top part of the plenus Bed and its absence from the post-plenus Bed succession, in the equivalent of which (higher part of the Plenus Marls Member) it is very common in southern England (Anglo-Paris Basin), is explained by ecological factors in stratigraphically complete sections (intra-shelf depressions) and by gaps in the stratigraphic records in swell settings. The distribution pattern of P. plenus suggests a preference for nearshore settings and a demersal mode of life.     

Ammonite biostratigraphy of the uppermost Hauterivian in the Betic Cordillera (SE Spain)

A detailed analysis of the stratigraphic distribution of ammonites from fourteen sections in the External Zones of the Betic Cordillera has enabled us to identify accurately the sequence of bioevents that take place throughout the uppermost Hauterivian and to propose a more precise biostratigraphic scheme for this interval. Thus, we have divided the two currently admitted zones (the Crioceratites balearis Zone and the Pseudothurmannia angulicostata auct. Zone) into several subzones. Four subzones can be recognised within the Cr. balearis Zone. The base of each subzone is defined by the first occurrence of one of four successive species belonging to the same Crioceratites lineage. These species are: Cr. balearis, Cr. binelli, Cr. krenkeli and Cr. angulicostatus. The Ps. ohmi Zone (which replaces the classical Ps. angulicostata Zone) can be divided into three subzones characterised by three successive species of the genus Pseudothurmannia: Ps. ohmi, Ps mortilleti (here considered as a senior synonym of Ps. catulloi) and Ps. picteti. According to the current definition, the first occurrence of Taveraidiscus hugii (OOSTER) marks the lower boundary of the Barremian stage. This event fits into a major faunal-renewal episode that begins in the upper part of the Ps. picteti Subzone.     

Composite Trace Fossil Assemblage in a Distal Carbonate Setting from the Tethys (Middle Jurassic,Betic Cordillera,Southern Spain)

Ichnological analysis of a Middle Jurassic carbonate surface from the Betic Cordillera (southern Spain) reveals a complex trace fossil assemblage, including softground Ophiomorpha, firmground Arenicolites, Thalassinoides and Gastrochaenolites, and hardground Trypanites as well as possible Gastrochaenolites. The ecological replacement in the macrobenthic community is interpreted according to successive suites that are controlled mainly by substrate consistency. Variations in composition and abundance of trace fossils between suites can be ecologically and/or taphonomically determined.     

Integration of subsidence and sequence stratigraphic analyses in the Cretaceous carbonate platforms of the Prebetic (Jumilla–Yecla Region), Spain

An integrated analysis of subsidence and sequence stratigraphy of the Cretaceous successions of the Jumilla–Yecla Region (Betics, SE Spain) is supported by abundant stratigraphical, sedimentological and palaeontological data, with the aim to document and explain the accommodation changes that controlled the evolution and architecture of the carbonate platforms generated during that time on the southern continental margin of Iberia. The Cretaceous shallow marine carbonates and clastics that extensively crop out in the Jumilla–Yecla Region are divided into 11 sequence sets (major stratigraphic units bounded by tectonically induced unconformities), which can be subdivided into several third order depositional sequences and their constituent system tracts. All these genetic units build up a regional chronostratigraphic framework, which is herein used to support subsidence calculations. From the results of the subsidence analysis, seven intervals with characteristic tectonosedimentary patterns were distinguished for Cretaceous time. From these intervals, the first three (respectively early Tithonian–early late Berriasian, late Berriasian–late Hauterivian, and latest Hauterivian to earliest late Albian) were controlled by extensional tectonics, strong enough to mask, during most part of the time, the long-term thermal subsidence inherent to the continental margin. This tectonism was related to the Iberia–Africa divergence and the opening of the North Atlantic. Later, the fourth interval (late Albian–mid Cenomanian) and the sixth interval (late Coniacian to late Santonian) were characterised regionally by, overall, homogeneous subsidence patterns controlled by thermal subsidence, sediment loading and a relative tectonic quiescence. Finally, the fifth and the seventh intervals (respectively latest Cenomanian–early Coniacian and Campanian–Maastrichtian) were characterised by strong tectonic movements and complex subsidence patterns which were related to changes in intraplate stresses related to the onset of the convergence between Africa and Iberia and with the evolution of the Bay of Biscay.     

Relationships between foraminiferal assemblages and depositional sequences in Jahrum Formation,Ardal area (Zagros Basin,SW Iran)

The Jahrum Formation was deposited in the foreland basin in southwest Iran (Zagros Basin). The Zagros mountain belt of Iran, a part of the Alpine–Himalayan system, extends from the NW Iranian border through to SW Iran, up to the strait of Hormuz. The various facies of the Jahrum Formation were deposited in four main genetically related depositional environments, including: tidal flat, lagoon, shoal and open marine. These are represented by 14 microfacies. The Jahrum Formation represents sedimentation on a carbonate ramp. Tidal flat facies are represented by fenestral fabric, stromatolitic boundstone and thin-bedded planes. Carbonate deposition in a shallow marine lagoon was characterised by wacke–packstone, dominated by various taxa of imperforate foraminifer. The shoals are made up of medium- to coarse-grained skeletal and peloidal grainstone. This facies was deposited predominantly in an active high energy wave and current regime, and grades basinward into middle ramps facies are represented by wackestones–packstones with a diverse assemblage of echinoderm and large benthic foraminifers with perforate wall. Outer ramp facies consist of alternating marl and limestones rich in pelagic foraminifera. There is no evidence for resedimentation processes in this facies belt. The sequence stratigraphy study has led to recognition of three third-order depositional sequences.     

Benthic foraminiferal assemblages of the Middle and Upper Jurassic sediments from the northeastern Alborz and western Koppeh Dagh,Iran: Systematic palaeontology and palaeoecology

This research is focused on a poorly studied Jurassic sequence in the eastern part of Alborz and Western Koppeh Dagh basins. The foraminifera are reported from Callovian (Middle Jurassic) to Tithonian (Upper Jurassic) sediments of the Farsian and Chaman Bid formations. The benthic foraminiferal associations belong to the families Ammodiscidae, Epistominidae, Hauerinidae, Hormosinidae, Ichthyolariidae, Lagenidae, Nodosariidae, Nubeculariidae, Ophthalmidiidae, Polymorphinidae, Rhabdamminidae, Saccamminidae, Spirillinidae, Spirocyclinidae, Textulariidae, Trocholinidae, and Vaginulinidae. In the studied area, the foraminifera are dominated by the families Nodosariidae, Vaginulinidae and Epistominidae. Palaeoecological analysis of the foraminiferal assemblages from the Farsian Formation indicates that these sediments were deposited on the inner to mid shelf environment, with normal salinity (euhaline), and relatively well oxygenated waters, with eutrophic conditions in the Goznawwi area and oligotrophic conditions in the Chaman Bid area. The foraminiferal assemblages in this study are the first record from Jurassic sediments of the eastern part of the Alborz and Koppeh Dagh basins in northern Iran.     

Recent benthic foraminiferal assemblages in deep high-energy environments from the Gulf of Cadiz (Spain)

The benthic environment in the Gulf of Cadiz, north-eastern Atlantic, is strongly affected by the Mediterranean outflow water undercurrent (MOW) which flows northwards along the western Iberian Margin at 500–1500 m water depth. Foraminiferal census counts of living and dead assemblages from 27 surface samples ranging from 103 to 1917 m water depth, and the examination of hard substrates reveal a close correlation of the fauna with the local hydrography and sediment facies. Four different faunal groups are separated by factor analysis of the living fauna. Assemblage 1 contains typical lower slope species and dominates samples from the lower MOW core layer and in the North Atlantic deep water below. Shelf edge foraminifera are common in assemblage 2a which shows the highest proportions in samples from 103 to 272 m. Assemblage 2b is dominated by upper slope species and suspension-feeders that are frequent in the upper MOW core layer and in distal settings between 396 and 901 m. Species from assemblage 3 prefer epibenthic habitats and are recorded with high proportions exclusively in the immediate flow paths of the upper MOW between 496 and 881 m. Colonisation structures and species composition of epibenthic assemblages from the proximal facies largely differ from those in distal settings. In general, epibenthic foraminifers only use elevated substrates under the influence of near-bottom flow. Under high current velocities, epibenthic foraminifers prefer large and heavy objects. They colonise high attachment levels where a maximum yield of advected food particles can be achieved. In distal settings at lower flow velocities, the elevation height does not exceed 20 mm above the surrounding sediment surface. This level is related to a hydrologic transition layer with high concentrations of suspended particles. The comparison of microhabitat preferences and faunal structure under high and low current velocities reveal that substrate stability may be a confining environmental variable for endobenthic and shallow epibenthic foraminifers. The observations also indicate that the preferential settling height of epibenthic foraminifera is related to the highest lateral flux rates of food particles within reach from the sea floor. A dynamic selection of elevated microhabitats is only used by 7.8% of all species recognised in the Gulf of Cadiz area.     

Microtaphonomy of bioclasts and paleoecology of microencrusters from Upper Jurassic spongiolithic limestones (External Prebetic,Southern Spain)

Microencrusters and microtaphonomic features of the Oxfordian spongiolithic limestones of the External Prebetic were studied using thin-section analysis. The spongiolithic limestone is a bioclastic-rich packstone with common echinoderm, mollusc and brachiopod remains. The bioclasts show a high fragmentation index and frequent microborings. The encrustation index (E _i) is higher for fragments of serpulids, ammonoids and bivalves, and increases with the initial grain-size of bioclasts. The main microencrusters consist of benthic microbial communities (BMC) and nubeculariids, as well as subordinate calcareous and siliceous agglutinated foraminifera, serpulids and bryozoans. BMC are usually the first colonizers, and encrusting foraminifera mainly appear on bioclasts larger than 2 mm. BMC dominate in well-developed encrustations on upward facing surfaces of larger bioclasts that are also colonized by foraminifera (nubeculariids and Subdelloidina). Bullopora, serpulids and bryozoans are more common on lower surfaces. The fact that the values of encrustation index, encrustation thickness and diversity of the microencrusters increase with the size of bioclasts is related to a higher stability and exposure time of the available bioclastic substrate. The microencruster distribution on upper and lower surfaces of large bioclasts may be related to photic control, space competition and/or predation avoidance.     

Coral biostromes of the Middle Jurassic from the Subbetic (Betic Cordillera,southern Spain): facies,coral taxonomy,taphonomy, and palaeoecology

Coral biostromes from the Camarena Formation (External Subbetic, Betic Cordillera) are reviewed under palaeoecologic, taphonomic, and palaeontologic aspects. The biostromes are dominated by phaceloid forms and are characterized by a typical shallow-marine microencruster assemblage with photophilic microencrusters and scarce microbial crusts. The abundance of stylinid corals and light-dependant microencrusters suggests oligotrophic conditions. Coral colonies were located among oolitic shoals that were unfavorable for coral growth. The corals were developed in phases without oolitic production alternating with phases of oolitic production, forming metric-scale sequences. A relative sea-level fall would have reduced the ooidal production and led to the deposition of thin layers of micritic facies in intertidal areas. The cementation and hardening of the bottom resulted in a hardground that was colonized by corals after a subsequent relative sea-level rise. The progressive increase of the energetic conditions induced an increasing production of ooids and the migration of oolitic shoals, which covered and finished the coral biostromes. Repetition of this process gave rise to sequences reflecting small pulses of oscillations in the relative sea level.     

New data (smaller foraminifers and correlation with depositional sequences) on the Las Llacerias section (Late Pennsylvanian,Cantabrian Mountains,NW Spain)

New sedimentological and paleontological information on the uppermost Moscovian and Kasimovian strata of the Las Llacerias section, a succession exposed in the Picos de Europa region (Cantabrian Mountains) that is considered to bear interest for the global correlation of the Upper Pennsylvanian subsystem, are presented. Based on sedimentological studies, three stratigraphic intervals can be established which record three successive episodes in the evolution of the carbonate platform. The study of the environmental evolution and sea-level fluctuations, as well as biostratigraphic fusulinoidean information, allow the correlation of this section with the synorogenic deposits of the Gamonedo-Cabrales area (northern Picos de Europa region). It is recognized that in the Las Llacerias strata, 7 of the 11 depositional sequences of the latter area are represented. The taxonomy and distribution of smaller foraminifers, a fossil group never studied before in this section, have been analysed. Data obtained show the presence of, at least, 30 genera. In some cases (Syzrania aff. bulbosa, Tezaquina, Mesolasiodiscus, Pseudotaxis and Hemidiscus), their record in the Las Llacerias section significantly extends the stratigraphic genus or species range. The potential role of Protonodosaria and Nodosinelloides species, as well as the acme of Hemigordius schlumbergeri for the correlation of the Kasimovian deposits is reinforced within this study.     

Late Jurassic sea-level fluctuations in NW Switzerland (Late Oxfordian to Late Kimmeridgian): closing the gap between the Boreal and Tethyan realm in Western Europe

In Late Jurassic times, the Swiss Jura carbonate platform occupied the transition between the Paris Basin and the Tethys and thus connects the Boreal and Tethyan realm. Up to now, the lack of index fossils in the Reuchenette Formation prevented a reliable correlation between both areas (its sediments are characterised by a prominent sparseness of index fossils). Now, seven recently in situ collected species of ammonites helped to establish a new sequence-stratigraphical frame for the platform sediments of the Reuchenette Formation in NW Switzerland. Based on biostratigraphical data, five third-order sedimentary sequences were assigned to the Late Oxfordian to Late Kimmeridgian. The upper three third-order sequences correspond to the Boreal sequences Kim3–5 of Hardenbol et al. (1998). The deduced large-scale sea-level fluctuations match those from other European regions (Spain, Russia). This biostratigraphically based sequence-stratigraphical frame is a prerequisite to refine correlations within a wider area covering the Swiss Jura and parts of adjacent France and Germany. Electronic Supplementary Material Supplementary material is available for this article at     

Sequence biostratigraphy and paleoenvironmental reconstruction in the Early Eocene Figols Group of the Tremp-Graus Basin (south-central Pyrenees, Spain)

The dinoflagellate cyst, palynofacies and foraminiferal records from the Early Eocene Figols Group of the Spanish Pyrenees exhibit major changes associated with relative sea-level fluctuations and variations in efficiency of the fluvial systems. The mixed siliciclastic-carbonate marine succession exposed in the Merli-Esdolomada area was deposited on the shelf in a tectonically active basin, under oxic conditions, in shallow to moderately deep marine waters (close to the lower boundary of the photic zone) influenced by river discharge from adjacent emerged lands. Sedimentary cycles are mainly recorded by fine-grained deposits. The paleoenvironmental interpretation of palynological and calcareous microfaunal records allows the definition of depositional sequences and enables to trace basinward surfaces identified in more proximal settings by means of sedimentological facies analysis. At the same time, the solid regional stratigraphic framework already available for the Figols Group allows new insights on the paleoecology of extinct taxa.The Merli-Esdolomada section (ME) spans two 3rd order sequences. The upper sequence reflects more marginal marine conditions than the lower one, thus pointing to an overall shallowing trend with time. In the lower sequence the maximum flooding interval is characterised by a rich and diverse microfauna, highest relative abundances of marine phytoplankton and typically neritic dinoflagellate cyst (dinocyst) assemblages dominated by Spiniferites and Cordosphaeridium. The final phase of the highstand systems tract, in proximity of the main sequence boundary, is characterised by a decrease in abundance and diversity of dinocysts, with the dominance of the lagoonal genus Polysphaeridium, and by decreased microfaunal diversity (discorbids, miliolids, larger foraminifers).Palynological records permit the reconstruction of activation and deactivation phases of the fluvial systems, variations in runoff from the hinterland, nutrient delivery to the sea and productivity in surface waters of the Tremp-Graus Basin. The overall abundance of Spiniferites and the scarcity of peridinioid cysts, Lingulodinium, Pediastrum and Botryococcus algae are interpreted to indicate oligotrophic conditions during the deposition of the investigated succession. Recurrent intervals where the temporary disappearance of Spiniferites corresponds to highest relative abundances of Operculodinium and herbaceous debris are the main evidence for river plumes and denote periods of enhanced fluvial discharge reflecting a Milankovitch-type cyclicity. The Rotalia group, which shows abundance peaks of Cuvillierina spp. in the shallower intervals, is often associated with these episodes, thus suggesting for this taxon more tolerance to turbidity than larger foraminifera. Within the maximum flooding zone, a Thalassiphora patula acme corresponding to the local disappearance of Homotryblium is deemed to record the distal expression of a fluvial activation which triggered water salinity stratification. Despite broad morphological similarities, Homotryblium exhibits more cosmopolitan preferences than Polysphaeridium, which is instead confirmed as a lagoonal euryhaline taxon. The increase of Spinizonocolpites pollen toward the top of the Figols Group records the northwestward migration of Nypa mangrove-palms from southern Europe during the mid Early Eocene.     

Lithostratigraphy and sedimentology of the latest Cretaceous-early Burdigalian Tamezzakht succession (Northern Rif, Morocco): consequences for its sequence stratigraphic interpretation

The Tamezzakht succession (Maastrichtian–middle Burdigalian), situated at the fringe between the Internal and the External zones, displays contrasting lithologies with abrupt facies changes, discontinuities, and/or coarse-grained calciturbidite in between. These criteria allow the definition of seven main lithostratigraphic formations.Depositional environments (oxygenation levels, trophic conditions, omission histories, among others) and/or transgressive/regressive trends are inferred from integrated sedimentologic data including facies change, cyclicity pattern and the textural composition of the turbidite facies tracts. Special emphasis is given to the ichnological features.Taking into account the extended time-range, the position between the internal zones and the external ones, as well as the clear differentiation into several contrasting sedimentary formations, the Tamezzakht succession is expected to provide useful stratigraphic data for the regional correlations.     

Jurassic biostratigraphy and paleoenvironmental evolution of the Malaguide complex from Sierra Espuña (Internal Betic Zone, SE Spain)

Jurassic studies in the Internal Zones of the Betic Cordillera are scarce since this zone is composed mainly of pre-Jurassic metamorphic rocks. Only the “Dorsal” and the Malaguide domains include fossiliferous Jurassic successions, as in Sierra Espuña (SE Spain), which is one of the bigger and well-exposed Jurassic outcrops of the Internal Zones. Collected Ammonite assemblages update and improve the precision of previous biostratigraphic data by the recognition of: the Domerian (= Upper Pliensbachian, in the Mediterranean Domain) Lavinianum (Cornacaldense Subzone), Algovianum (Ragazzoni, Bertrandi, Accuratum and Levidorsatum Subzones) and Emaciatum (Solare and Elisa Subzones) Zones; the Lower Toarcian Polymorphum and Serpentinum Zones; the Middle Toarcian, Bifrons and Gradata Zone; the Upper Toarcian Reynesi Zone; the Lower/Upper Bajocian, the Lower Callovian Bullatus and Gracilis Zones; the Middle/Upper Oxfordian Transversarium, Bifurcatus, Bimammatum and Planula Zones; and the Lower and Upper Kimmeridgian Platynota, Strombecki, Divisum and Beckeri Zones.The paleoenvironmental evolution of the Malaguide Jurassic at Sierra Espuña shows similarities with other Mediterranean Tethyan paleomargins. The biostratigraphic precision along with the litho- and biofacies analyses has enabled the interpretation that the Malaguide paleomargin evolved as a passive margin, developing shallow carbonate platforms, until the Domerian (Lavinianum Zone). Then, the platform broke up (Domerian, Lavinianum Zone-Upper Toarcian, Reynesi Zone) with the beginning of the rifting stage, beginning the development of horst-graben systems and the coeval drowning of the area. This stage ended in the upper Lower Callovian (Gracilis Zone) to the Middle Oxfordian (Transversarium Zone) interval, starting the drifting stage, which accentuated the horst-graben systems, leading to the deposition of condensed nodular limestones in the raised sea bottom.     

Integrated analyses of litho- and biofacies in a Pliocene cyclothemic, alluvial to shallow marine succession (Tuscany, Italy)

Lithofacies analysis of the upper part of the Pliocene succession of the Valdelsa basin (central Italy) unravelled a number of depositional environments, ranging from alluvial plain to coastal, to marine. Strata are arranged in a hierarchy of elementary and composite unconformity-bounded units. A palaeoecological study of macro- (molluscs) and microfossils (pollen, dinocysts, foraminifera) allowed to finely reconstruct sub-environments within fine-grained terrestrial, coastal and marine deposits and thence to track the spatial and temporal change of physical conditions. The stacking pattern of sedimentary units highlights the lateral switching of onshore-offshore gradients and documents relative sea-level changes. These units are interpreted in a sequence stratigraphic framework. Elementary depositional sequences are arranged to form six composite depositional sequences, in turn encased within two major synthems. This hierarchy of unconformity-bounded sedimentary units suggests that sea-level variation has occurred at different time-frequencies. Glacio-eustasy and active tectonism are discussed as the main forcing factors regulating the different scales of sedimentary cyclicity.