Artinskian–Wordian antitropical rugose coral associations: A palaeogeographical approach

Recent investigations in the Urals and East-European Platform as well as study of corals collections from South Primorye (Russian Far East) and South-Eastern Pamirs have been undertaken. Antitropical rugose associations include taxa that are bounded in their distribution by the temperate zones of the Boreal and Perigondwanan realms. They occur sporadically in tropical latitudes but never form abundant and diverse communities. Antitropical associations are represented by the so-called ‘Cyathaxonia fauna’ (sensu lato), predominating in two selected stratigraphic intervals. The abrupt change of taxonomic composition from colonial to ‘Cyathaxonia fauna’ allows the separation of two assemblages: (i) mid Artinskian–Kungurian and (ii) Roadian–Wordian. The key regions for comparison are the Urals (mid Artinskian–Kungurian), Spitsbergen (Kungurian–Wordian), East-European Platform (Roadian), Texas (mid Artinskian–Kungurian), South Primorye (Wordian–Capitanian), South-Eastern Pamirs (Upper Artinskian), and the Sverdrup Basin (Wordian). The Late Artinskian fauna of the South-Eastern Pamirs and Wordian faunas of South Primorye bear features of mixed assemblages. A few models of the origination of antitropical assemblages are acceptable: (i) the convergent parallel evolution of Lophophyllidium in the Northern Hemisphere and Southern Hemisphere, (ii) a similar evolution trend developed in parallel in three geographically distant regions: Verbeekiella, Pseudowannerophyllum, and “Pseudoverbeekiella”, and (iii) immigration of some species within temperate zones caused by current circulation changes both in the Northern and Southern Hemispheres, as well as northward spreading of terranes in the Perigondwanan Realm.     

Reproducibility and reliability of the Pliensbachian calcareous nannofossil biohorizons from the Basque-Cantabrian Basin (Northern Spain)

Based on calcareous nannofossil assemblages identified in four expanded and well-dated sections from the Basque-Cantabrian Basin, the main objective of this paper is to improve the knowledge of the Pliensbachian calcareous nannofossil events, and to calibrate these events to the ammonite zones established for this area. The semiquantitative analysis of more than 140 smear slides from the Tudanca and Santotis sections, and the re-analysis of more than 200 smear slides from the Camino and San Andrés sections, have been carried out in order to describe the succession of calcareous nannofossil assemblages. Related to their composition changes, we have recognized and calibrated to the ammonite zones two main events: the first occurrences (FOs) of Similiscutum cruciulus and Lotharingius hauffii, and six secondary events: the FOs of Biscutum novum, Biscutum grande, Biscutum finchii, Lotharingius barozii and the FCOs (first common occurrences) of Calcivascularis jansae and L. hauffii. In the Camino and San Andrés sections, we also identify the FOs of Biscutum dubium, Bussonius prinsii and Lotharingius sigillatus. The obtained data allow us to assess the degree of reproducibility of the Pliensbachian calcareous nannofossil events in the studied area. The biohorizon succession recognized in the Basque-Cantabrian Basin are compared to those proposed for NW Europe, Lusitanian Basin, Italy and Southern France.     

High-resolution biostratigraphy of the Tournaisian-Visean (Carboniferous) boundary interval, Mokrá quarry, Czech Republic

This paper summarizes the results of investigations carried out in the Mokrá quarry since 2006 on the biostratigraphy of the Tournaisian-Visean (T-V) boundary interval. It also integrates previous results obtained by J. Kalvoda and collaborators. The main focus is on the boundary itself, but stratigraphically lower and higher levels have been investigated as well to provide a biostratigraphical context spanning the late Tournaisian to early Visean. This stratigraphical level has been the focus of intense international research in the recent years under the auspices of the Subcommission on Carboniferous Stratigraphy (SCCS) in order to find a new criterion and reference section (Global Stratotype Section and Point, GSSP) for the base of the Visean Stage. The appearance of Eoparastaffella simplex from its ancestor E. “ovalis” and the Pengchong section (Guangxi, southern China) have recently been proposed by the Task Group on the Tournaisian-Visean Boundary and ratified by the SCCS as the new biostratigraphic criterion and GSSP for the base of the Visean, respectively. The sequence exposed in Mokrá is not suitable as a GSSP, notably because it is an active quarry, but it contains most of the foraminifer and conodont guides allowing a high-resolution biostratigraphy of the boundary interval. In addition, it contains abundant trilobites. For these reasons, it constitutes one of the best sections across the T-V boundary in Europe and can serve as a useful additional reference.     

The Early Cambrian acritarch Skiagia and its significance for global correlation

Global records of Early Cambrian acritarchs from the Skiagia plexus reveal that they are stratigraphically significant and can be used as biostratigraphic markers. Skiagia ornata and Skiagia ciliosa have a cosmopolitan distribution and the levels of their first appearance datums are proposed to serve as biostratigraphic horizons for interregional correlation. These levels are close to the lower boundary of the undefined Cambrian Stage 3, and within the Stage 3, respectively. The acritarch assemblage diagnostic of the Heliosphaeridium dissimilare-S. ciliosa Zone of Baltica is recorded worldwide and some species are traced on four of the Cambrian continents that include South Australia, South China and Laurentia. This supports the intercontinental correlation of certain Lower Cambrian strata and establishes the time equivalence between the regional trilobite zones to which these strata are attributed. The regional zonation is briefly reviewed for the purpose of comparing and evaluating the acritarch ranges. The biostratigraphic correlation of the Lower Cambrian strata, belonging to different faunal provinces, is based for the first time on the same fossil species, which have a cosmopolitan distribution and well-defined first appearance datums, and on the entire diagnostic acritarch assemblages.     

Paleocene-Early Eocene ostracodes from the Southern Galala Plateau (Eastern Desert, Egypt): Taxonomy, impact of paleobathymetric changes

Ostracode faunas obtained from nine sections spanning the Paleocene-Early Eocene interval from a platform-basin transect in the Southern Galala Plateau area (Eastern Desert, Egypt) have been investigated. The study focuses on taxonomy and biostratigraphy of the ostracode assemblages across the P/E boundary, with supporting comments on paleoecology and paleobiogeography. The studied nine sections yielded 60 taxa belonging to 39 genera. Five species are new. The P/E transition is characterized by the appearance of new taxa rather than extinctions. During the Early and early Late Paleocene, the ostracode assemblages throughout the study area are largely similar, being dominated by middle-outer neritic taxa. In the late Late Paleocene and Early Eocene, changes in the paleobathymetry from deeper marine environments in the distal area in the south to shallower marine environments in the proximal area in the north become pronounced. Many of the recorded taxa have a wide geographic distribution throughout the Middle East and North Africa. Similarities with basins of West Africa are also found, reflecting faunal exchanges between this area and southern Tethys during the Paleocene and Early Eocene.     

Refinements of calcareous nannofossil biostratigraphy at the Miocene/Pliocene Boundary in the Mediterranean region

The high-resolution quantitative study of the calcareous nannofossil assemblages in two Mediterranean deep-sea successions (ODP Sites 969B and 975B) encompassing the Miocene/Pliocene boundary allows the recognition of a set of reliable bioevents useful to detecting the base of the Zanclean stage. The results have been successfully compared with two on-land sections (Cava Serredi, Tuscany, and Montepetra borehole, Marche Region, Central Italy). This study confirms that Ceratolithus acutus and Triquetrorhabdulus rugosus, the markers traditionally used for identifying the Miocene/Pliocene Boundary are very rare in the Mediterranean area and cannot be used for biostratigraphic correlation. Conversely, the absence interval (paracme) of Reticulofenestra pseudoumbilicus and the distribution range of a new species belonging to the Reticulofenestra genus (Reticulofenestra zancleana nov. sp.) show high biostratigraphical potential. The position of the new biohorizons has been compared to those of the planktonic foraminifers events, and correlated to the CaCO₃ cycles reconstructed for the two sections. On the basis of these new nannofossil bioevents, Rio et al.’s (1990) MNN12 biozone is subdivided into three subzones, thus improving the biostratigraphic resolution of the Early Pliocene.     

Unusual assemblages of Late Cretaceous silicoflagellates from the Canadian Archipelago

Devon and Ellef Ringnes islands in the Canadian Arctic Archipelago contain well-preserved Santonian through early Campanian silicoflagellates. These occur in three unusual assemblages, which comprise three biostratigraphic zones. The oldest, the Vallacerta tumidula Partial Range Zone of Santonian age, contains an extremely variable microflora that includes species of the poorly-known genus Variramus, two new species of Cornua, and a new genus Umpiocha. The Schulzyocha ruppelii Range Zone of early Campanian age includes several species of the new genus Schulzyocha, reflecting quadrate silicoflagellate skeletal morphologies that lack a basal structure. The youngest assemblage includes the poorly-known species Cornua trifurcata, the nominative taxon of the C. trifurcata Partial Range Zone (proposed by McCartney et al., in press c; emended herein), which allows a correlation with a silicoflagellate-bearing sequence from the Horton River area, Northwest Territories of Canada. This report presents information on 24 silicoflagellate taxa, proposes 2 new genera, Schulzyocha and Umpiocha, and describes 13 new species and 1 new combination. All of these new taxa disappear by the top of the Campanian Cornua trifurcata Partial Range Zone. These assemblages reveal a new history of silicoflagellate evolution prior to the late Campanian, the period from which most of our prior knowledge about Cretaceous silicoflagellates was derived. The assemblages show progressive change from skeletons with highly variable morphologies to more stable silicoflagellate skeletal geometry. Two important Corbisema species, C. apiculata and C. archangelskiana, appear to be derived from separate lines within Cornua in the latest Santonian and early Campanian. The important Cretaceous genus Lyramula makes its first appearance at the beginning of the Campanian.     

Badenian and Sarmatian s.str. from the Carpathian area: Taxonomical notes concerning the Hungarian and Romanian small vertebrates and report on the ruminants from the Felsőtárkány Basin

Over the last decade, important progress has been made in the study of the mammal successions from Hungary and Romania. A critical review of the taxonomy of the published small mammals is provided herein, as well as some new data and an overview of the accompanying vertebrate fauna (excluding fishes) in their stratigraphic context. In addition, the first data regarding the ruminants from Mátrasz?l?s and Fels?tárkány are presented. This contribution aims to characterize the middle to earliest late Miocene fossil record from these countries, and provide important data for the chrono(bio)stratigraphic and palaeoenvironmental studies at the European scale.     

Stratigraphy and palynology of the Pennsylvanian continental Buçaco Basin (NW Iberia)

The Buçaco Basin is a Pennsylvanian continental basin located along an important NNW–SSE strike structure (Porto-Tomar-Ferreira do Alentejo shear zone) that separates the Ossa-Morena and Central Iberian Zones of the Iberian Variscan Fold Belt in central western Portugal. The shear zone controlled the sedimentation in the basin and probably its post-sedimentary evolution. Sedimentation is initially alluvial with characteristic red sandstones, breccias and conglomerates. A gradual change to a fluvial (and probably lacustrine) type of sedimentation is observed with finning-upward cycles of gravel conglomerates, sandstones and organic-rich mudstones with occasional coal seams. Three representative sections were sampled for palynology and seventeen samples yielded sporomorphs with moderate to poor preservation. The palynological content from the alluvial sediments shows low diversity and poorly preserved assemblages dominated by Triquitrites spp., Densosporites spp., Laevigatosporites spp., and other taxa associated with siliciclastic environments or rheophytic mires. The fluvial and lacustrine sediments show a dramatic increase in diversity with an abundant, typical peatland microflora including sporomorphs such as Endosporites spp., Lycospora spp. and Monoletes spp., but also marginal peat and siliciclastic substrate taxa such as Densosporites spp., Latensina/Cordaitina spp., and Florinites spp. Other common taxa are Cheiledonites spp., Crassispora spp., Dictyotriletes-like miospores (mostly fragments), Potonieisporites spp., and Wilsonites spp. The presence and considerable abundance of Potonieisporites novicus and Cheiledonites cf. major is indicative of the middle to upper Potonieisporites novicus-bhardwajii–Cheiledonites major (NBM) miospore biozone of Western Europe, corresponding to the late Stephanian (early Gzhelian).     

Late Viséan–Serpukhovian foraminifers in the Montagne Noire (France): Biostratigraphic revision and correlation with the Russian substages

The “calcaires à Productus” of the Montagne Noire (Aude-Hérault, southern France) are carbonate lenses embedded within a thick Carboniferous siliciclastic complex. Foraminiferal assemblages in some of the larger carbonate lenses are typically representative of the late Viséan and Serpukhovian. Eleven new species of foraminifers are described: Hemidiscopsis variabilis, H. pilleae, Planohowchinia rara, P. redondensis, Spireitlina minima, Rectoendothyra japhetensis, Mikhailovella enormis, Cribrospira? perretae, Pojarkovella occidentalis, Parabiseriella vailhanensis, and Biseriella delicata. Eight foraminiferal biozones are defined; they are based on the first occurrence of some taxa, and could be used for other regions of southern France (e.g., Mouthoumet and the Pyrenees). These biozones are informally named as A to H. Due to the problems with classical biozonations and substages in northern England as well as Belgium and northern France, the biozones established herein are mostly compared with the Russian standard substages. Thus, biozones A and B are correlated with the Mikhailovian, corresponding to the latest Asbian and earliest Brigantian in western Europe; biozones C, D and E are correlated with the Venevian, equivalent to the upper part of the early Brigantian in western Europe. Therefore, biozones A–E form part of the late and latest Viséan. The stratigraphically younger biozones F, G and H contain foraminiferal assemblages correlated with the Tarusian, Steshevian and Protvian, respectively.