A fan delta succession rich in water escape structures (Upper Turonian, Brandenberg, Austria): Possible record of paleoseismicity

Summary The Upper Turonian of Brandenberg (Austria) is based by a transgressive fan delta succession rich in water escape structures that, at least in part, may have formed in association with earthquakes. The investigated fan delta is among the oldest deposits of the Lower Gosau Subgroup (Upper Turonian to Lower Campanian), a terrestrial to neritic succession that unconformably overlies older carbonate rocks. In its subaerial part, the fan succession consists mainly of conglomerates deposited from mass flows, interlayered with red claystones to siltstones. Along the fringe of marine transgression, beachface/channel mouth conglomerates and bioturbated siltstones to fine sandstones accumulated. The marine part of the fan delta succession consists mainly of cross-laminated and hummocky cross-laminated arenites deposited in a wave/storm-domainated shoreface. Excellent preservation of sedimentary lamination throughout and near absence of bioturbation indicate (intermittently) rapid sediment accumulation. Intercalated shoreface conglomerates are present as compound channel-fills, and as thin sheets alongside and off channels. Offshore transport of gravels to cobbles into the shoreface may have been driven by river floods (in the most proximal positions) and by storm rip currents (farther seaward). Towards the top of the succession, conglomerate sheets disappear, and the arenites become bioturbated. In the succession of shore zone arenites, abundant water escape structures include distorted/convoluted lamination, short fluidization planes, tabular fissures (some associated with offset of beds), pods and lenses of internal breccias, pillow beds up to more than 1 m thick, and hitherto undescribed, cyclindrical structures (“onion structures”) built by concentrically arranged planes interpreted as water escape routes. The tabular fissures, internal breccias and the pillow beds are closely similar to water escape structures documented from historical earthquakes and from inferred paleo-earthquakes. Storm wave loading or wave-induced microseisms are considered less probable triggers of the larger dewatering structures. Water escape structures represent an hitherto unappreciated, although not strictly diagnostic, indicator of syndepositional tectonism in the Upper Cretaceous of the Eastern Alps.     

Benthic foraminifers and paleoecology of a Holocene shelly concentration, Salado Basin, Argentina

Foraminiferal fossil assemblages of the shelly concentration, which represents the type section of Cerro de la Gloria Member of Las Escobas Formation, were analyzed for the first time. Taxonomic, quantitative and taphonomical analyses were made in order to obtain paleoenvironmental (physical as well biological) information. The complexity of the internal structure of the taphocoenoses was analyzed to infer the history of the final concentration process. The shell bed of Channel 15 corresponds to a shoreface longshore bar deposited in a brackish, unstable, wave-dominate coast. Shoreface and beach (foreshore) regressive facies were recognized. Taphonomic processes have modified the paleobiocoenoses by the selective preservation of autochthonous elements and by the addition of parautochthonous fauna from relict beachs and lagoons. Thus, the taphocoenoses is a within-habitat time-averaged assemblage composed of species that inhabit shallow shelf marine environments. Discrimination of autochthonous and parautochthonous fauna was possible based on taphonomic signatures of tests. The addition of the parautochthonous elements was related with longshore currents and littoral drift, and with high-energy events, probably with storm-waves, when erosion of the Pre-Mid Holocene substrate was more intense. Thus, the contribution of parautochthonous fauna is directly related with lithology and therefore, with dynamic of the paleoenvironment: in the shoreface, autochthonous fauna dominates in clastic sands with lamination and parallel stratification, whereas parautochthonous elements dominate in shoreface shelly gravels and in the foreshore sands. In the upper part of the section (beach facies), mainly parautochthonous elements related with erosion of the Pre-Mid Holocene substrate was recognized, since the shoreface was only periodically affected by marine processes, i.e., during storms.     

Carbonate facies evolution from the late albian to Middle Cenomanian in Southern Istria (Croatia): influence of synsedimentary tectonics and extensive organic carbonate production

Summary During the Late Albian, Early and Middle Cenomanian in the NW part of the Adriatic Carbonate Platform (presentday Istria) specific depositional systems characterised by frequent lateral and vertical facies variations were established within a formerly homogeneous area, ranging from peritidal and barrier bars to the offshore-transition zone. In southern Istria this period is represented by the following succession: thin-bedded peritidal peloidal and stromatolitic limestones (Upper Albian); well-bedded foreshore to shoreface packstones/grainstones with synsedimentary dliding and slumping (Vraconian-lowermost Cenomanian); shoreface to off-shore storm-generated limestones (Lower Cenomanian); massive off-shore to shoreface carbonate sand bodies (Lower Cenomanian); prograding rudist bioclastic subaqueous dunes (Lower to Middle Cenomanian); rudist biostromes (Lower to Middle Cenomanian), and high-energy rudist and ostreid coquina beds within skeletal wackestones/packstones (Middle Cenomanian). Rapid changes of depositional systems near the Albian/Cenomanian transition in Istria are mainly the result of synsedimentary tectonics and the establishment of extensive rudist colonies producing enormous quantities of bioclastic material rather than the influence of eustatic changes. Tectonism is evidenced by the occurrence of sliding scars, slumps, small-scale synsedimentary faults and conspicuous bathymetric changes in formerly corresponding environments. Consequently, during the Early Cenomanian in the region of southern Istria, a deepening of the sedimentary environments occurred towards the SE, resulting in the establishment of a carbonate ramp system. Deeper parts of the ramp were below fair-weather wave base (FWWB), while the shallower parts were characterised by high-energy environments with extensive rudist colonies, and high organic production leading to the progradation of bioclastic subaqueous dunes. This resulted in numerous shallowing- and coarsening-upwards clinostratified sequences completely infilling formerly deeper environments, and the final re-establishment of the shallow-water environments over the entire area during the Middle Cenomanian.     

A Mediterranean Holocene restricted coastal lagoon under arid climate: Case of the sedimentary record of Sabkha Boujmel (SE Tunisia)

The Holocene sedimentary record of Sabkha Boujmel (SE Tunisia) is expressed by a shallowing-upward carbonate lagoon-tidal flat cycle (2.3 m thick) unconformably overlying continental silt-sandy sediment, Late Würmian in age. The sedimentary package of this cycle starts with transgressive marginal shallow marine (intertidal to subtidal) bioclastic sands grading upwards to black mudstone, rich in organic matter (T.O.C. up to 1.3%) deposited within a lagoon protected from the sea by Upper Pleistocene lithified sand spits.The uppermost part of the cycle is represented by oobioclastic carbonate sands covered with dead biodegraded microbial mats and/or reddish sands of aeolian origin deposited in intertidal to supratidal environments. The facies arrangement, particularly the spatial distribution of the ancient and the more recent microbial mats, records the progressive infilling of the lagoon as well as the progradation of the shoreline during the last 2000 years. The organic-rich facies which provide an age varying between 4130 and 6800 yr B.P. were deposited when the Boujmel lagoon started to be progressively separated from the Mediterranean Sea.The main factors controlling the facies and the thickness variation are the local topographic sea-floor irregularities most likely controlled by the inheritance morphology resulting from an important fluviatile digging that occurred during the last glacial maximum, the relative sea-level fluctuations, the hydro-isostatic rebound and the climate.     

Sedimentary facies from the modern coral reefs,Jordan Gulf of Aqaba,Red Sea

Summary Sixty-three sediment samples collected from the modern fringing reefs off the Jordan coast (Gulf of Aqaba, Red Sea) have been analysed in order to determine variations of composition and texture by using correspondence factor analysis. From the shore seawards, the following physiographic zones are recognized: beach; shallower backreef zone; reef flat zone; forereef zone including sandy or coral-built slopes. Eight sediment facies and subfacies can be recognized on the basis of total component composition and foraminiferal assemblages and four sediment facies can be recognized using grain-size data. Wellsorted, fine to medium, quartzofeldspathic sands (terrigenous facies) occur on beaches and outer sandy slopes close to wadi mouths. Backreef areas exhibit relatively well-sorted fine sands of terrigenous-coral and Miliolidae-Soritidae facies. Poorly sorted, coarse sands of coral-coral-line algal and Homotremid facies characterize reef flats and the upper parts of coral-built forereef areas, which respecitively display an Amphistegina-Spirolina subfacies and an Acervulina one. Poorly sorted, medium sands of coralmolluscan-foraminiferal (Amphistegina-Acervulina) facies are restricted to the lower parts of the forereef zone. Latcral limits of the various biofacies coincide with the distribution of the related organic communities.     

Sediment dynamics during the Cenomanian-Turonian (cretaceous) oceanic anoxic event in Northwestern Germany

Summary The epicontinental pelagic to hemipelagic Upper Cenomanian and Lower Turonian successons of the Lower Saxony Basin (northwestern Germany) are represented by the Rotpl?ner facies on swells (multicolored marls and marly limestones) and the basinal Black Shales facies (marly limestones (Turbidites), black shales) in the local basins. Facies units are described with their lateral and vertical variation from both depositional environments and their correlation is discussed. The distinct Cenomanian-Turonian boundary facies is due to dilution of pelagic carbonate by siliciclastic material, volcanic ashfall, and substantial changes in carbonate, sedimentation rates by about an order of magnitude. The observed sediment geometries origin from preservation of sediments in areas where normal faults occur and erosion of the formerly deposited units in unfaulted areas (preservation of relicts). Erosion and redeposition on swells occurs in thin (<50 cm thick) debris flow and mud flow channels (1–100 m wide), sheet flows, and by turbidity currents. During the Upper Cenomanian the sediment transport is governed by gravity flow which is increasingly superimposed by storm deposition during the Lower Turonian. Lense-shaped tempestites (probably below average storm wave base) occur at the base of the Turonian (entry ofMytiloides hattini) in morphologically highest swell positions and migrate across the entire basin until the late Lower Turonian. The basinal facies is characterised by laminated and biotrubated black shales and mud turbidites that vary over short distances. Laminae show graded bedding and erosive contacts and were deposited by turbidity currents. Intercalated marly limestones are mud turbidities (some mudflows) that are coarsening upwards until the early Lower Turonian. Larger slides occurred predominantly in the late Upper Cenomanian. The sediment distribution is closely related to sea level changes and reflects short- and long-term fluctuations generating comparable stratigraphic trend in the sections, although basin and swell facies are always clearly distinguished. Lokal basin margins (e.g. primary fordeeps of sal domes) were probably limited by larger normal faults that prevented facies gradation between both depositional environments.     

A late Pleistocene progradational clastic shoreface succession in Jamaica: Implications for the preservation potential of the echinoid Leodia

A section in the Late Pleistocene Port Morant Formation of Jamaica shows a progradational deltaic succession passing from offshore muddy sands, through shoreface to foreshore deposits. The transition zone/lower shoreface has abundant Ophiomorpha burrows and contains common examples of the echinoid Leodia cf. sexiesperforata (Leske). Modern Leodia occur in shallow marine carbonate sands, and the Port Morant occurrence is the first record of abundant Leodia in the geological record. Despite their strong test construction that should give Leodia a high preservation potential, these echinoids have a poor fossil record because the environments in which they lived are rarely preserved. Consequently, the fossil record is biased towards species that occur in environments with high preservation potential.     

The Cambrian of Malaysia

The Cambrian of Malaysia is best represented by the quartzose Machinchang Formation in Langkawi, Kedah, northwest Peninsular Malaysia. It is divisible into three members. The oldest Hulor Member (>1260 m thick) is a coarsening upward succession of rhythmically interlayered graded siltstone, mudstone and clayey sandstone deposited as a prograded prodelta deposit. The middle Chinchin Member (>1575 m thick) is a fining upward succession of quartzose conglomerate and sandstone subdivisible into three beds. The lowest Anak Datai Bed (575 m thick) is made up of graded bedded, cross-bedded pebbly sandstone and conglomerate of estuarine channel-fills and thin to thick beds of low angle, planar cross-bedded sandstone with heavy mineral concentrations deposited as upper shoreface to beach deposits. The Temurun Bed (340 m thick) is of upper estuarine deposits of wavy-bedded sandstone and pebbly sandstone, fine tuffs and thin argillites. The upper Tengkorak Bed (>200 m thick) spans the Cambro-Ordovician boundary and consists of thick tabular bedded upper shoreface to beach fine sandstone with interbeds of fine rippled sandstone, acid tuff beds and mudstone belonging to a series of barrier beach complexes. The youngest Jemurok Member (>420 m thick) is a fining upward succession of siltstone, mudstone and hummocky cross-bedded sandstone and thin limestone deposited in storm influenced shoreface to back barrier lagoon with tidal channel environments. It has fragmentary trilobites, brachiopods, abundant trace fossils and the Kinneyian wrinkle marks.The overall sequence belongs to a highly destructive, wave-influenced delta deposit with a series of preserved beach-ridge complexes. Clastic sedimentation was reduced by peneplation of the source area as shown by the finer and thinner beds that grade into limestone of the overlying Ordovician Setul Formation.     

An enigmatic,diminutive theropod footprint in the shallow marine Pliensbachian Hasle Formation,Bornholm, Denmark

A well‐preserved three‐toed footprint, measuring 34 mm in length from a very small predatory dinosaur with an estimated hip height of 153 mm and a total body length around 50 cm including tail, is reported from the type section of the marine Lower Jurassic (Pliensbachian), Hasle Formation on the Danish island of Bornholm in the Baltic Sea. The morphology of the footprint is similar to the ichnogenus Stenonyx Lull 1904 from the contemporaneous Pliensbachian Szydlowek site in Poland. Apart from the Polish material, footprints from diminutive dinosaurs are rare and reported from few other localities around the world. The occurrence of a diminutive dinosaur footprint in a shallow marine sandstone is enigmatic. The well‐defined morphology of the footprint, together with the very small size of the trackmaker, excludes the possibility that the track was emplaced by a swimming or wading animal. At the type locality where the footprint was found the formation consists of ferruginous coarse siltstone and very fine‐grained sandstone, showing hummocky and swaley cross‐stratification and rare large‐scale trough cross‐bedding and planar lamination. Deposition took place mainly in the upper shoreface in a storm‐dominated environment 1 km west of the N?S‐oriented faulted coastline. The formation becomes thinner and finer grained with heterolithic intercalations towards the south, indicating coast‐parallel transport in this direction. The extreme uniformity in sedimentary facies as seen in two nearby fully cored boreholes shows that the accommodation space created by rapid subsidence along the fault was continuously filled in to upper shoreface level by rapid longshore sediment influx from the north. In quiet periods with easterly winds and extreme low‐water low tide, the small dinosaur creating the newly found footprint is interpreted to have walked in shallow beach pools, thus explaining the strange occurrence of the footprint in a marine deposit.     

Facies control on lower Cambrian wrinkle structure development and paleoenvironmental distribution, southern Great Basin, United States

Assessing the role that physical processes play in restricting microbial mat distribution has been difficult due to the primary control of bioturbation in the modern ocean. To isolate and determine the physical controls on microbial mat distribution and preservation, a time in Earth’s history must be examined when bioturbation was not the primary control. This restricts the window of observation primarily to the Precambrian and Cambrian, which precede the development of typical Phanerozoic and modern levels of bioturbation. Lower Cambrian strata of the southern Great Basin, United States, record the widespread development of seafloor microbial mats in shallow shelf and nearshore settings. These microbial mats are recorded by wrinkle structures, which consist of millimeter-scale ridges and sinuous troughs that represent the former presence of a surface microbial mat. Wrinkle structures within these strata occur exclusively within heterolithic deposits of the offshore transition, i.e., between fair-weather wave base and storm wave base, and within heterolithic tidal-flat deposits. Wrinkle structures are not preserved in siltstone-dominated offshore deposits or amalgamated shoreface sandstones. The preservation of wrinkle structures within these environments is due to: (1) the development of microbial mats atop clean quartz-rich sands for growth and casting of the structures; and (2) the draping of the microbial mat by finer-grained sediment to inhibit erosion. The exclusion from offshore deposits may be due to a lack of sufficient sunlight, whereas the restriction from the shoreface is likely due to the amalgamation of proximal tempestites, resulting in the erosion of any incipient microbial mat development.     

Depositional environment and biofacies characterization of the Upper Pennsylvanian–Lower Permian deposits of the San Salvador Patlanoaya section (Puebla, Mexico)

The San Salvador Patlanoaya section (Puebla State of Mexico) has been subdivided into seven informal members labeled A–F. Members C–F have been dated as Missourian to Leonardian (equivalent to Kasimovian to Kungurian, i.e. lower Upper Pennsylvanian to upper Lower Permian). Members C–E display a shallowing-upward trend as does member F. The biodiversity of these carbonate deposits outcropping in the San Salvador Patlanoaya section is relatively low, although multiple microfossils (algae, small foraminifera, fusulinids and fish remains) are represented. Member C consists of calcarenitic limestone interpreted as distal tempestites interbedded with shaly limestone facies. These storm beds are composed mainly of silt, sand-sized quartz grains and bioclasts. Member D corresponds to coarse bioclastic limestones represented by calcareous tempestites and channel beds with erosional bases. Member E is composed of green shales and cross-bedded sandstones and gravelly conglomerates. Member F corresponds to a condensed package of limestones and interbedded siliciclastics and is Cisuralian (Early Permian) in age. Member G consists of condensed black shales and limestone nodules. The results of the study have significant implications for recognition of climatic and/or sea-level fluctuations in bioclastic–siliciclastic facies during the Late Pennsylvanian–Early Permian. The skeletal limestones and channel sandstones, common throughout the Pennsylvanian–Permian section, provide a constraint on palaeobathymetry, with the water depth fluctuating frequently around a position below, but near, the storm wave base.     

Sequence stratigraphic significance of sedimentary cycles and shell concentrations in the Upper Jurassic-Lower Cretaceous of Kachchh, western India

Upper Jurassic and Lower Cretaceous siliciclastic shallow water sediments of the Kachchh Basin, western India, form strongly asymmetric coarsening-upward cycles, which are interpreted as recording changes in relative sea level (deepening-shallowing cycles). These cycles correspond to depositional sequences, in which deposits of the lowstand systems tract are not present, the sequence boundary coinciding with the transgressive surface. Shell concentrations are found in the transgressive lags at the base of the transgressive systems tract (TST), in the maximum flooding zone (MFZ), and at or close to the top of the highstand systems tract. They belong to six assemblages, five of them dominated by large bivalves such as Seebachia, Herzogina, Gryphaea, Gervillella, Megacucullaea, Pisotrigonia and Indotrigonia, the sixth by the coral Amphiastraea. Three types of shell concentrations can be distinguished that differ from each other in a number of ecological and taphonomic features, such as species diversity, preservation quality, orientation in cross-section, percentage of disarticulation, and degree of biogenic alteration. Characteristic features of concentrations at the base of the TSTs are moderate time-averaging, sorting, a preferred convex-up orientation, and nearly total disarticulation of shells. They are suggestive of an environment in which reworking and local transport were frequent events. Similar features are shown by concentrations near the tops of the HSTs, except that there shells were largely concentrated in lenses and in pavements rather than in beds as in the transgressive lags. Associated sedimentary structures indicate deposition above fair weather wave base in a high-energy environment. Concentrations occurring in the MFZ, in contrast, are autochthonous and highly time-averaged, having accumulated during times of low rates of sedimentation below storm wave base. This is supported by their high preservation quality (comparatively high percentage of articulated shells, shells of infaunal organisms commonly preserved in life position), biogenic alteration being the most important taphonomic agent. The dominant elements of these shell concentrations, i.e. Seebachia, Megacuccullaea, and Indotrigonia in the Upper Jurassic, and Pisotrigonia in the Lower Cretaceous, are endemic to the Ethiopean faunal province and belong to lineages that rapidly evolved during this time period.     

Age and composition of carbonate shoreface sediments, Kailua Bay, Oahu, Hawaii

The origin, age, and dynamics of carbonate sediments in Kailua Bay on Oahu, Hawaii, are described. The shoreface (from shoreline to 4 km offshore) consists of a broad (5 km²) fringing coral reef ecosystem bisected by a sinuous, shore-normal, sand-filled paleostream channel 200–300 m wide. The median grain diameter of surface sands is finest on the beach face (<0.3 mm) and increases offshore along the channel axis. Kailua sands are >90% biogenic carbonate, dominated by skeletal fragments of coralline algae (e.g. Porolithon, up to 50%) followed by the calcareous green alga Halimeda (up to 32%), coral fragments (1–24%), mollusc fragments (6–21%), and benthic foraminifera (1–10%). Sand composition and age across the shoreface are correlated to carbonate production. Corals and coralline algae, principal builders of the reef framework, are younger and more abundant in sands along the channel axis and in offshore reefal areas, while Halimeda, molluscs, and foraminifera are younger and more dominant in nearshore waters shoreward of the main region of framework building. Shoreface sediments are relatively old. Of 20 calibrated radiocarbon dates on skeletal constituents of sand, only three are younger than 500 years b.p.; six are 500–1000 years b.p.; six are 1000–2000 years b.p.; and five are 2000–5000 years b.p. Dated fine sands are older than medium to coarse sands and hence may constitute a reservoir of fossil carbonate that is distributed over the entire shoreface. Dominance of fossiliferous sand indicates long storage times for carbonate grains, which tend to decrease in size with age, such that the entire period of relative sea-level inundation (∼5000 years) is represented in the sediment. Despite an apparently healthy modern coral ecosystem, the surficial sand pool of Kailua Bay is dominated by sand reflecting an antecedent system, possibly one that existed under a +1–2 m sea-level high stand during the mid- to late Holocene. Accepted: 20 December 1999     

Late Cenomanian–Early Turonian facies development and sea-level changes in the Bodenwöhrer Senke (Danubian Cretaceous Group, Bavaria, Germany)

The Upper Cenomanian–Lower Turonian litho-stratigraphic units of the Danubian Cretaceous Group of the proximal Bodenwöhrer Senke (Regensburg, Eibrunn and Winzerberg formations, the latter consisting of a lower Reinhausen Member and an upper Knollensand Member), have been investigated with a focus on facies analysis and sequence stratigraphy. Analyses of litho-, bio-, and microfacies resulted in the recognition of 12 predominantly marine facies types for the Eibrunn and Winzerberg formations. Petrographic and paleontological properties as well as gradual transitions in the sections suggest that their depositional environment was a texturally graded, predominantly siliciclastic, storm-dominated shelf. The muddy–siliceous facies types FT 1–3 have been deposited below the storm wave-base in an outer shelf setting. Mid-shelf deposits are represented by fine- to medium-grained, bioturbated, partly glauconitic sandstones (FT 4–6). Coarse-grained, gravelly and/or shell-bearing sandstones (FT 7–10) developed in the inner shelf zone. Highly immature, arkosic coarse-grained sandstones and conglomerates (FT 11 and 12) characterize an incised, high-gradient braided river system. The Winzerberg Formation with its general coarsening- and thickening-upward trend reflects a regressive cycle culminating in a subaerial unconformity associated with a coarse-grained, gravelly unit of marine to fluvial origin known as the “Hornsand” which is demonstrably diachronous. The overlying Altenkreith Member of the Roding Formation signifies the onset of a new transgressive cycle in the early Middle Turonian. The sequence stratigraphic analysis suggests that the deposition of the Upper Cenomanian and Lower Turonian strata of the Bodenwöhrer Senke took place in a single cycle of third-order eustatic sea-level change between the major sequence boundaries SB Ce 5 (mid-Late Cenomanian) and SB Tu 1 (Early–Middle Turonian boundary interval). The southeastern part of the Bodenwöhrer Senke was flooded in the mid-Late Cenomanian (Praeactinocamax plenus transgression) and a second transgressive event occurred in the earliest Turonian. In the central and northwestern parts of the Bodenwöhrer Senke, however, the initial transgression occurred during the earliest Turonian, related to pre-transgression topography. Thus, the Regensburg and Eibrunn formations are increasingly condensed here and cannot be separated anymore. Following an earliest Turonian maximum flooding, the Lower Turonian Winzerberg Formation filled the available accommodation space, explaining its constant thickness of 35–40 m across the Bodenwöhrer Senke and excluding tectonic activity during this interval. Rapid sea-level fall at SB Tu 1 terminated this depositional sequence. This study shows that Late Cenomanian–Early Turonian deposition in the Bodenwöhrer Senke was governed by eustatic sea-level changes.     

Onshore expansion of benthic communities after the Late Devonian mass extinction

A detailed ichnological analysis of the Upper Devonian–Lower Mississippian Bakken Formation of sub‐surface Saskatchewan and the partially coeval Exshaw Formation of Alberta indicates the presence of an anomalous ichnofacies gradient. The distal Cruziana Ichnofacies, which in rocks of other ages is restricted to lower‐offshore facies, here ranges from this setting to the lower shoreface. No archetypal Cruziana Ichnofacies is present in these deposits. This pattern is interpreted as resulting from the differential effects of the Late Devonian mass extinction in shallow‐water ecosystems. The onshore expansion evidenced by ichnological data is consistent with the pattern displayed by the body‐fossil record, which indicates a re‐invasion of shallow‐water environments by the Palaeozoic evolutionary fauna during the Late Devonian and into the Early Carboniferous. The ichnofauna studied is overwhelmingly dominated by deposit feeders, with suspension feeders being notably absent, further underscoring the importance of trophic type as a selectivity trait during mass extinctions.     

Palynoflores dans la coupe de l'Albien de Foz do Folcao (Portugal)

In the area of Lisbon (Portugal) near Foz do Folcao and along the sea-shore, the transgressive facies of the marly 0611 Albian may be seen sesting on the “Upper continental sandstones of Almargem”. On the basis of the variety and of the relative frequencies of reticulate pollen grains in particular, the following age assessment can be made. The topmost part of the “Upper sandstones of Almargem” as well as the lowermost transgressive facies, just underlaying the albian levels with associated faunas, are suggested to be middle Albian.     

Continental, brackish and marine carbonates from the Lower Cretaceous of Kolone–Barbariga (Istria, Croatia): stratigraphy, sedimentology and geochemistry

During the Early Cretaceous, wide areas of the Dinaric–Adriatic Carbonate Platform emerged for long periods. The Hauterivian–Barremian carbonates from Kolone–Barbariga show a few typical examples of lacustrine facies with dinosaur bones and brackish/palustrine facies. The sequence of the platform is made for the most part by subtidal and intertidal limestones. The bone levels are located in a large depression few meters deep in the uppermost Hauterivian marine limestones. The filling facies of this depression are made by oncolitic rudstones and algal boundstones, which represent marginal lacustrine facies, and by laminated limestones, thin stromatolitic levels and distal fringes of rudstones which represent relatively open lacustrine facies. The fossil content is characterized by rare charophyte stems, ostracods, gastropods and plant remains, while typical marine fauna is absent. At the Hauterivian–Barremian boundary a major emersion event has been observed, then a slow transgressive phase occurred. The transgressive facies are primarily made by mudstones with ostracods, charophytes and Spirillina (brackish and probably freshwater facies), wackestones with Ophtalmidiidae and rare dasyclad algae, storm layers with gastropods and miliolids and breccia-like dinoturbated beds. Wackstones, packstones and very rich in dasyclad grainstones outcrop at the top of the section, representing the maximum of the transgression. Trace elements content, carbon and oxygen stable isotope analyses have been performed to aid the palaeoenvironmental interpretation. In this geological setting, Barium seems to discriminate between brackish and freshwater facies. The isotopic values of the marine carbonates appear to depend on early diagenetic processes, meanwhile lacustrine facies seem to show a weak signal of the depositional environment.     

Précisions biostratigraphiques nouvelles sur le Berriasien des Djebel Nara et Sidi Kralif (Tunisie centrale)

The biostratigraphy of Sidi Kralif formation is precised by means of correlation of calpionellid, ostracod and ammonite faunas in three sections of Nara Mountain (Central Tunisia). The Upper Tithonian (Jacobi zone pars) and the Lower Berriasian (Grandis zone) show 40 m of pelagic sediments above the Nara dolomitic formation. The Middle Berriasian (Occitanica zone) under the same facies points out variations of thickness (60 to 100 m). Only the lower part of the Upper Berriasian (Paramimounum subzone) is present at the upper part with neritic facies (bioclastic limestones, sandstones, dolomites, breccia) and some changes of thickness (10 to 100 m). With the Upper Berriasian begins the thick detritic Meloussi formation.     

Depositional processes of ribbon carbonates in Middle Cambrian of Iran (Deh-Sufiyan Formation,Central Alborz)

A variety of ribbon carbonates of the Deh-Sufiyan Formation (Middle Cambrian) in Central Alborz Range of northern Iran are studied to provide facies characterization and paleoenvironmental interpretation of ribbon carbonates on shallow-marine carbonate platforms. Seven types of ribbon carbonates are divided based mainly on sedimentary structures, ichnofossils, and bed geometry, which represent deposition during different phases of storm-induced processes. The different features of the storm deposits in ribbon carbonates such as hummocky and swaley cross-stratification, planar lamination, and combined-flow-ripple cross-stratification were formed by combined flows. Identification and interpretation of ichnological signatures and the spatial arrangement of succession of sedimentary structures are used to further refine sedimentary interpretations of parameters such as wave energy, substrate properties, variability in sedimentation rates, and proximality-distality trends of a wave-dominated marine ramp sequence. Successions from individual storm events reflect deposition during increasing combined oscillatory and unidirectional flow succeeded by the waning stages. The study provides depositional processes and models of various ribbon carbonates that may be useful for facies interpretation of ribbon rocks elsewhere.     

Trace fossil associations related to facies of an upper Ordovician low wave energy shoreface and shelf, Oslo-Asker district, Norway

Three trace fossil associations have been identified from facies interpreted as low wave energy upper, middle and lower shoreface deposits, transitional shoreface/shelf deposits and open epicontinental shelf deposits. These were developed in pre-regressive, regressive and transgressive phases associated with eustatic sea level changes caused by the upper Ordovician glaciation. The three associations are the Skolithos-Diplocraterion association, the Diplichnites-Phycodes association and the Thalassinoides association. The Skolithos-Diplocraterion association inhabited upper, middle and lower shoreface environments, the Diplichnites-Phycodes association a lowermost shoreface environment and the Thalassinoides association inhabited offshore epicontinental shelf environmcnts. The Skolithos-Diplocraferion and Diplichnites-Phycodes associations bear strong affinities with previously described Skolithos ichnofacies assemblages (indicating shoreline environments) and the Cruziana ichnofacies forms (indicating shallow water environments down to wave base) respectively. The Thalassinoides assemblage, however, closely compares with assemblages described from Mesozoic epicontinental shelf sequences. Trace fossil diversity achieves a maximum in the lowermost shoreface environment and reduces in deeper water and shallower water environments. This accords with diversity patterns identified in analogous Jurassic epicontinental palaeonvironments. The stratigraphic distribution of some trace fossil association boundaries accords with those of contemporary body fossil associations. However, several body fossil associations are included within the volume of distribution of a single trace fossil assemblage. □ Trace fossil association, shoreface and shelf, Oslo district, upper Ordovician.