A ‘Problematic fossil’ revealed:Pycnoporidium ? eomesozoicum Flügel, 1972 (Late Triassic,Tethys)—not an enigmatic alga but a strophomenid brachiopod (Gosaukammerella n.g.)

Summary The microproblematicumPycnoporidium ? eomesozoicum Flügel, 1972, from Upper Triassic reefs of the Alpine-Mediterranean region, Turkey Oman and Iran (originally interpreted as possible alga) represents the type species of a new strophomenid brachiopod genus (Gosaukammerella n.g.). The genus is characterized by a very small, millimeter-sized plano-convex shell, whose ventral valve is attached to the substratum (mainly sponges) by symmetrically arranged outgrowths developing from a pseudopunctate, lamellose foliated shell wall and composed of densely spaced subparallel ‘tubes’ comparable with productide spines secreted by papillose extensions of the mantle.Gosaukammerella seems to be the only reliable candidate for the existence of post-Paleozoic strophomenid (productid ?) brachiopods. Gosaukammerella eomesozoica is restricted to possibly cryptic, shaded reef environments inhabited predominantly by sponges serving as substrates for micromorphic brachiopods.     

Stratigraphy,facies and synsedimentary tectonics in the Jurassic Rosso Ammonitico Veronese (Altopiano di Asiago,NE Italy)

Summary The red, pelagic limestones of the Rosso Ammonitico Veronese (Upper Bajocian-Tithonian) of the Altopiano di Asiago area can be subdivided into eight facies. They differ from each other in structure (bedding style, presence and type of nodularity) and texture (nature of components, grain-vs mud-support, compactional features). Several discontinuities could be recognized, based on sedimentological or biostratigraphic evidence. In the context of a drowned platform, where sediments essentially consist of skeletal remains of both planktonic and benthic organism, the different facies are interpreted as reflecting a varying influence of currents on the winnowing of micrite and on triggering early cementation. Early cementation in turn, controlled the patterns of bioturbation and the response of sediments to later compaction and pressure-dissolution. At times, microbial mats, of unidentified nature, were important in trapping and binding sediment, giving rise to early lithified nodules and layers of stromatolitic aspect. The Rosso Ammonitico Veronese can be subdivided into three units: lower Rosso Ammonitico (RAI: Upper Bajocian-Lower Callovian), middle Rosso Ammonitico (RAM: Upper Callovian-Middle Oxfordian), and upper Rosso Ammonitico (RAS: Lower Kimmeridgian-Tithonian). Frequent ammonite moulds allow the precise dating of the base and top of each unit, and the documentation of facies heteropies and hiatusses in the more fossiliferous RAS. The lower unit (RAM) is massive and essentially nodular; the middle unit (RAM) is well bedded, non-nodular, and cherty; the upper unit (RAS) is richer in clay and typically nodular. The RAI and the RAS are present everywhere, though significant facies and thickness changes affect particularly the RAS; the RAM is much more variable, ranging from 0 to 10 metres. These variations, that may be gradual or abrupt, are inter-preted as the result of Middle-Late Callovian block-faulting which generated an irregular sea floor topography where the swells were more exposed to currents that continuously removed sediments, inducing long-lasting periods of nondeposition. Sediments preferentially accumulated in the adjacent lows. A confirmation of this hypothesis is provided by evidence of synsedimentary tectonics, described for the first time in the Rosso Ammonitico Veronese. Neptunian dykes, both vertical and horizontal, are developed at the top of the RAI and are filled with laminated sediments or collapse breccias. Glides of metre-size blocks and slumps are present at the top of the RAI and at the base of the RAM, respectively. Cm-thick layers of mud supported breccias are intercalated in the upper part of the RAI and within the RAM: they are interpreted as seismites. All these features document a tensional regime that generated fractures in more or less lithified sediments and failure along steep fault scarps or gently dipping slopes of tilted fault blocks. Recognition of this Callovian-Oxfordian tectonic activity shows that, after the Bajocian drowning, the Trento Plateau did not simply experience a uniform and general foundering: a small-scale block-faulting was still active and affected the pattern of facies distribution.     

The upper cretaceousLacazina limestone in the Basco-Cantabrian and Iberian basins of northern Spain: Cold-water grain associations in warm-water environments

Summary The Upper Santonian to Lower CampanianLacazina Limestone consists of massive, often amalgamated beds of packstones and grainstones which were deposited in a shallow marine environment. The most abundant skeletal components are miliolid foraminifera, echinoderm, bivalve and bryozoan fragments, peloids and sparse red algae. Small, solitary corals only occur sporadically. Hermatypic corals, sponges and green algae are missing. The series which reaches thicknesses between 60 m and 160 m, was sampled at intervals of 0.5 m at five localities. The petrographic features throughout the series are mainly a product of changing depositional energy. The limestones are well cemented. Diagenesis is characterized by a transition from marine phreatic to burial cementation. Syntaxial and blocky calcite cements predominate over early acicular to bladed and microgranular cements. The faunal association within theLacazina Limestone exhibits features typical for temperate water i.e.foramol carbonates. On the other hand, oxygen (δ¹⁸O =-1.7 to −6.3 ‰ PDB) and carbon (δ¹³C to 3.0‰ PDB) isotope values of diagentically unaltered bivalve shells indicate warm surface waters corresponding better to the palaeogeographical situation of theLacazina Limestone. Nutrient-surplus is proposed as a limiting factor preventing the development of reefs and finally ofchlorozoan sediments. In the sense of sequence stratigraphy, theLacazina Limestone is interpreted to contain transgressive and highstand systems tracts. This interpretation fits well into theHaq-Vail-curve. The series shows no visible high-frequency cyclicity in the field. Several cycles were found by means of principle component analysis and spectral analysis. Their relationships to the Milankovitch spectrum are discussed. The ammonite fauna of the unit and of preceding sediments (late Coniacian to early Campanian) is described and some inoceramids are figured. They permit—for the first time—the exact dating of theLacazina Limestone in the Basco-Cantabrian Basin (BCB) and throw light on a prominent faunal change at the Coniacian/Santonian boundary. The Cenomanian to Coniacian ammonite faunas which were dominated by endemic Tethyan pseudoceratitic faunas are replaced by cosmopolitan species dominated by Madagascan elements. This drastic change permits speculations about the installation of a new oceanic current system in the Santonian.     

Sedimentology of the Upper Triassic reef complex at the Hochkönig Massif (Northern Calcareous Alps,Austria)

Summary The Upper Triassic Dachsteinkalk of the Hochk?nig Massif, situated 50 km south of Salzburg in the Northern Calcareous Alps, corresponds to a platform margin reef complex of exceptional thickness. The platform interior limestones form equally thick sequences of the well known cyclic Lofer facies. Sedimentation in the reef complex was not so strongly controlled by low-amplitude sea-level oscillations as was the Lofer facies. The westernmost of the 8 facies of the reef complex is an oncolite-dominated lagoon, in which wave-resistant stromatolite mounds with a relief of a few metres were periodically developed. The transition to the central reef area is accomplished across the back-reef facies. In the back-reef facies patch reefs and calcisponges appear. The proportion of coarse bioclastic sediment increases rapidly over a few hundred metres before the central reef area is encountered. The central reef area consists of relatively widely spaced small patch reefs that did not develop wave-resistant reef framework structures. The bulk of the sediment in the central reef area is coarse bioclastic material, provided by the dense growth of reef organisms and the wave-induced disintegration of patch reefs. Collapse of the reef margin is recorded by the supply of large blocks of patch reef material to the upper reef slope. Additionally, coarse, loose bioclastic debris was supplied to the upper reef slope and this was incorporated into debris flows on the reef slope and turbidites found at the base of the slope and in the off-reef facies. Partially lithified packstones and wackestones of the lower to middle reef slope were modified by mass movement to form breccia and rudstone sheets. The latter reach out hundreds of metres into the off-reef facies environment. A reef profile is presented which was derived by the restoration of strike and dip information. In conjunction with constraints imposed by sedimentary facies related to slope processes, the angle of slope in the reef margin area ranged from 11° to 5°, forming a concave (dished downwards) slope. Water depth estimations require that the central reef area did not develop in water of less than 10 metres depth. At the reef margin water depths were about 30 metres, at the base of the reef slope 200 metres and deepening in the off-reef facies to 250 metres. While previous work on reef complexes from this type of setting suggests growth in a heavily storm-dominated environment, the present author finds little evidence for the storm generation of the fore reef breccias, although there is good evidence for storm-influenced sedimentation and reworking in the central reef area. Post-depositional processes were characterised by continued slope processes causing brecciation and hydraulic injection of red internal sediments downwards into the reef slope and off-reef limestones. Hydrothermal circulation caused a number of phases of post-depositional (diagenetic) brecciation. There appears not to have been an important period of emergence at the Triassic/Jurassic boundary.     

Middle paleozoic waulsortian-type mud mounds in Southern Fergana (Southern Tien-Shan,commonwealth of independent states): The shallow-water atoll model

Summary Several Waulsortian-type mud mounds nearly 500 m thick and about 5 km long occur in the Middle Paleozoic carbonate section of the Aktur nappe in the mountains on the right bank of Isfara river. These buildups form a well developed barrier system that stretches along the South Ferganian carbonate platform margin and divides the carbonate complex into a fore-reef and a back-reef part. The time of the mounds' most active growth was from the Late Silurian (Ludlow) to the Middle Devonian (Eifel). Three main facies types can be recognized in the mud mounds: 1. micritic core facies, 2. sparitic flank facies and 3. loferitic capping facies. The central massive or crudely bedded part of the mounds consists of white or light grey clotted micrite. Macrofossils are rare. The sparitic flank facies in contrast consists of coarse and densely packed crinoidal wackestone-floatstones with some brachiopod shell debris. Solitary rugose corals, tabulate corals, stromato-poroids and fragments of mollusks are also abundant. The tops of the mounds are usually covered with loferitic pelmicrites or oolitic grainstone caps. Stromatactis-like structures are very rare and poorly developed in the South Ferganian mud mounds. However, almostin all such mounds horizons of calcitic breccias can be found. In order to explain all the features found in the Fergana mounds an ‘atoll-like’ model has been proposed which starts the evolution of the mud mounds with a small nucleus bioherm. The main stage of the evolution corresponds to an atoll-like structure developing on the surface of shallow water platforms. White clotted micrite of the mound core facies is interpreted as a accumulation of fine-grained sediment in an inner lagoon flanked by crinoidal bar deposits. The mound flank facies represents the atoll rim deposits from where the carbonate mud is derived. The capping loferitic facies is considered as tidal flat deposit that developed on top of the buildups during the last stage of its evolution. The knoll shape of the mounds is explained by the retreat of the atoll flanking crinoidal bars back into the inner lagoon during the rise in sea level. Stromatactis-like structures of small cavities filled with sparry calcite owe their existence to burrowing organisms. Calcitic breccias are interpreted as paleokarst collapse breccias. They indicate that the tops of the mud mound became subaerially exposed. Other evidence for a subaerial exposure can be seen in the occurrence of Variscian ‘black and white’ limestone gravel on the tops of some mud mounds. According toWard et al. (1970) these sediments were produced above the sea level at the edge of hypersaline lakes situated on islands.     

The building stones of Roman Sagalassos (SW Turkey): Facies analysis and provenance

Summary Different types of builing stones have been macro-scopically and petrographically characterized at the ancient city of Sagalassos (SW Turkey). The natural building stones include limestone, conglomerate, breccia, marble, travertine, granite and sand-to siltstone of different qualities. The provenance of most of the building stones may be related to local lithological units, both in the immediate area of the city and on its territory. Also, some stone types were clearly imported from considerable distance. Throughout the history of the city, local beige and pink good quality limestone remained the most important building stone. Both the high quality white limestone from the territory of the city and the marbles imported from a distance of 250 km, represent only a small fraction of the total amount of building stones used. While the use of the white limestone can be considered to form a clear but limited trend from the Trajanic period (98–117 AD) onwards, the import of the marbles must be considered as a rare event. The selection of building stone went hand in hand with the appreciation for structural strength and suitability for carving complex architectural decoration, together with the desire to obtain a polychrome architecture.     

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.     

Early cretaceous serpulid limestones: Chachao formation,Neuquen basin,Argentina

Summary Colonial serpulids (Sarcinella) are common within some limestones of the lower Chachao Formation (Valanginian) near Malargüe city at the northern border of the Neuquem basin, Argentina. The shallowing-upwards sequence is characterized by low-energetic micritic carbonates. The serpulid limestones mark the transition from a carbonate ramp stage to a platform stage.     

Dasycladales from the Upper Maastrichtian of Salento Peninsula (Puglia, southern Italy)

Summary A rich dasycladalean assemblage, mainly consisting of new taxa, has been discovered in upper Maastrichtian coarse bioclastic limestones of shelf margin facies cropping out along the southeastern coast of Salento peninsula (Puglia, Southern Italy). It consists of 8 species grouped into 6 genera:Cymopolia decastroi Parente 1994;C. barattoloi Parente, 1994;Zittelina fluegeli n.sp;Jodotella koradae (Dieni, Massari & Radoicic, 1983) nov. comb.;Barattoloporella salentina n. gen. n. sp.;Morelletpora dienii n. sp.;Neomeris spp. (two different species). Zittelina fluegeli n. sp. is characterized by an ovoid thallus with calcification made by a calcareous wall enveloping only the proximal part of the branches (except in basal whorls) and by closely packed, and partly coalescent, calcified ampullae arranged all around the median and distal portion of branches. The transferral ofNeomeris (Larvaria) koradae Dieni, Massari & Radoicic, 1983 into the genusJodotella, with the new combinationJodotella koradae, is proposed on the basis of new observations on the number and arrangement of fertile ampullae. The new genusBarattoloporella, type-speciesBarattoloporella salentina n. gen. n. sp., is erected for dasycladalean algae characterized by a segmented thallus. Each segment consists of: a) basal and apical sterile whorls made by primary branches only, b) central fertile whorls made by primary branches bearing in terminal position one fertile ampulla and one or two secondary branches. morelletpora dienii n. sp. is characterized by a segmented thallus with barrel shaped to pear shaped repetitive elements, consisting of simple whorls of first order branches only. Shape of the branches varies from regularly phloiophorous to more or less differentiated in a stalk and a swollen portion, with or without a subterminal constriction. This is by far the most diverse dasycladalean assemblage ever found in the Maastrichtian. Its diversity supports the conclusion that, within the Late Cretaceous, the Maastrichtian represents a maximum in dasycladalean diversity. Its taxonomic composition strenghtens the hypothesis that dasycladaleans were hardly affected by K/T mass extinction.     

The Cenomanian of northern Germany: facies analysis of a transgressive biosedimentary system

A facies analysis of the epicontinental marine Cenomanian sediments of northern Germany shows the presence of 17 facies types (FTs, including several subtypes) which can be assigned to three facies associations: 1) an inner shelf facies association (FT 1–8) with high amounts of terrigenous material and/or high-energy depositional features, 2) a middle shelf facies association (FT 9–15) of predominantly calcareous sediments with moderate amounts of generally fine siliciclastics, and 3) an outer shelf facies association (FT 16–17) of low-energy, fine-grained, pure limestones. These three facies associations roughly correspond to the well-known lithological units of the Cenomanian of northern Germany, i.e., the Essen Greensand/Cenomanian Marls complex, the Pläner Limestones, and the Poor rhotomagense Limestones. The sediments were deposited on a northward-dipping homoclinal ramp with more-or-less shoreline-parallel facies belts. The sediment composition on this ramp-like shelf was a function of the varying importance of three different sediment sources: 1) terrigenous input from the south (Rhenobohemia), generally fining/decreasing in a proximal–distal (i.e., S–N) direction; 2) production of skeletal grains, mainly by macrobenthic organisms; and 3) settling of planktic carbonate (mainly calcispheres and calcareous nannofossils). In response to decreasing water energy with increasing water depth, the seaward decreasing terrigenous influence, and increasing planktic carbonate production, increasingly finer and more calcareous sediments were deposited in a proximal–distal transect. This rather straightforward picture was slightly modified by highest carbonate accumulation rates (planktic and benthic) on the middle shelf, forming a mid-shelf depocenter (fossiliferous, calcisphere-rich Pläner Limestones). Time-transgressive, southward-directed onlap of this biosedimentary system during the Cenomanian caused a significant retreat of the coastline towards the south and a retrogradational stacking of facies belts, explaining the broadly similar facies development and lithology of Cenomanian successions across northern Germany. The boundaries of the lithological units, however, tend to be considerably diachronous in a distal–proximal transect. In the late Middle and early Late Cenomanian, a final drowning and facies levelling (“oceanization”) is indicated by the widespread deposition of uniform calcareous nannofossil mudstones (Poor rhotomagense Limestones).