Correlation of Mississippian (Upper Viséan) foraminiferan,conodont, miospore and ammonoid zonal schemes,and correlation with the Asbian–Brigantian boundary in northwest Ireland

The microbiota of the upper Viséan (Asbian–Brigantian) rocks in the Lough Allen Basin in northwest Ireland is analysed. The Middle Mississippian sequence studied extends from the upper part of the Dartry Limestone/Bricklieve Limestone formations of the Tyrone Group to the Carraun Shale Formation of the Leitrim Group. The rocks have been traditionally dated by ammonoid faunas representing the B_2a to P_2c subzones. The Meenymore Formation (base of the Leitrim Group) also contains conodont faunas of the informal partial‐range Mestognathus bipluti zone. The upper Brigantian Lochriea nodosa Conodont Zone was recognized by previous authors in the middle of the Carraun Shale Formation (Ardvarney Limestone Member), where it coincides with upper Brigantian ammonoids of the Lusitanoceras granosus Subzone (P_2a). Foraminifera and algae in the top of the Dartry Limestone Formation are assigned to the upper Cf6γ Foraminifera Subzone (highest Asbian), whereas those in the Meenymore Formation belong to the lower Cf6δ Foraminifera Subzone (lower Brigantian). The Dartry Limestone Formation–Meenymore Formation boundary is thus correlated with the Asbian–Brigantian boundary in northwest Ireland. For the first time, based on new data, a correlation between the ammonoid, miospore, foraminiferan and conodont zonal schemes is demonstrated. The foraminiferans and algae, conodonts and ammonoids are compared with those from other basins in Ireland, northern England, and the German Rhenish Massif. Historically, the Asbian–Brigantian boundary has been correlated with several levels within the P_1a Ammonoid Subzone. However, the new integrated biostratigraphical data indicate that the Asbian–Brigantian boundary in northwest Ireland is probably located within the B_2a Ammonoid Subzone and the NM Miospore Zone, but the scarcity of ammonoids in the Tyrone Group precludes an accurate placement of that boundary within this subzone. Copyright © 2006 John Wiley & Sons, Ltd.     

Biostratigraphy,microfacies and depositional environments of upper Viséan limestones from the Burren region,County Clare,Ireland

The Burren region in western Ireland contains an almost continuous record of Viséan (Middle Mississippian) carbonate deposition extending from Chadian to Brigantian times, represented by three formations: the Chadian to Holkerian Tubber Formation, the Asbian Burren Formation and the Brigantian Slievenaglasha Formation. The upper Viséan (Holkerian–Brigantian) platform carbonate succession of the Burren can be subdivided into six distinct depositional units outlined below. (1) An Holkerian to lower Asbian unit of skeletal peloidal and bryozoan bedded limestone. (2) Lower Asbian unit of massive light grey Koninckopora‐rich limestone, representing a shallower marine facies. (3) Upper Asbian terraced limestone unit with minor shallowing‐upward cycles of poorly bedded Kamaenella‐rich limestone with shell bands and palaeokarst features. This unit is very similar to other cyclic sequences of late Asbian age in southern Ireland and western Europe, suggesting a glacio‐eustatic origin for this fourth‐order cyclicity. (4) Lower Brigantian unit with cyclic alternations of crinoidal/bryozoan limestone and peloidal limestone with coral thickets. These cycles lack evidence of subaerial exposure. (5) Lower Brigantian bedded cherty dark grey limestone unit, deposited during the maximum transgressive phase of the Brigantian. (6) Lower to upper Brigantian unit mostly comprising cyclic bryozoan/crinoidal cherty limestone. In most areas this youngest unit is truncated and unconformably overlain by Serpukhovian siliciclastic rocks. Deepening enhanced by platform‐wide subsidence strongly influenced later Brigantian cycle development in Ireland, but localized rapid shallowing led to emergence at the end of the Brigantian. A Cf5 Zone (Holkerian) assemblage of microfossils is recorded from the Tubber Formation at Black Head, but in the Ballard Bridge section the top of the formation has Cf6 Zone (Asbian) foraminiferans. A typical upper Asbian Rugose Coral Assemblage G near the top of the Burren Formation is replaced by a lower Brigantian Rugose Coral Assemblage H in the Slievenaglasha Formation. A similar change in the foraminiferans and calcareous algae at this Asbian–Brigantian formation boundary is recognized by the presence of upper Asbian Cf6γ Subzone taxa in the Burren Formation including Cribrostomum lecomptei, Koskinobigenerina sp., Bradyina rotula and Howchinia bradyana, and in the Slievenaglasha Formation abundant Asteroarchaediscus spp., Neoarchaediscus spp. and Fasciella crustosa of the Brigantian Cf6δ Subzone. The uppermost beds of the Slievenaglasha Formation contain a rare and unusual foraminiferal assemblage containing evolved archaediscids close to tenuis stage indicating a late Brigantian age. Copyright © 2006 John Wiley & Sons, Ltd.     

Late Dinantian (Lower Carboniferous) platform carbonate stratigraphy of the Buttevant area North Co. Cork,Ireland

A thick sequence of late Dinantian (Asbian–Brigantian) carbonates crop out in the Buttevant area, North Co. Cork, Ireland. A mud-mound unit of early Asbian age (the Hazelwood Formation) is the oldest unit described in this work. This formation is partly laterally equivalent to, and is overlain by, over 500 m of bedded platform carbonates which belong to the Ballyclogh and Liscarroll Limestone Formations. Four new lithostratigraphic units are described within the platform carbonates: (i) the early Asbian Cecilstown Member and (ii) the late Asbian Dromdowney Member in the Ballyclogh Limestone Formation; (iii) the Brigantian Templemary Member and (iv) the Coolbane Member in the Liscarroll Limestone Formation. The Cecilstown Member consists of cherty packstones and wackestones that are inferred to have been deposited below fair-weather wavebase. This unit overlies and is laterally equivalent to the mud-mound build-up facies of the Hazelwood Formation. The Dromdowney Member is typified by cyclic-bedded kamaenid-rich limestones possessing shell bands, capped by palaeokarst surfaces, with alveolar textures below and shales above these surfaces. The carbonates of this unit were deposited at or just below fair-weather wavebase, the top of each cycle culminated in subaerial emergence. The Templemary Member consists of cyclic alternations of subtidal crinoidal limestones capped by subtidal lagoonal crinoid-poor, peloidal limestones possessing coral thickets. Intraclastic cherty packstones and wackestones characterize the Coolbane Member, which is inferred to have been deposited below fair-weather wavebase but above storm wavebase. The early Asbian Cecilstown Member has a relatively sparse micro- and macrofauna, typified by scattered Siphonodendron thickets, archaediscids at angulatus stage and common Vissariotaxis. Conversely, macro- and microfauna is abundant in the late Asbian Dromdowney Member. Typical late Asbian macrofossils include the coral Dibunophyllum bipartitum and the brachiopod Davidsonina septosa. The base of the late Asbian (Cf6γ Subzone) is recognized by the first appearance of the foraminifers Cribrostomum lecompteii, Koskinobigenerina and the alga Ungdarella. The Cf6γ Subzone can be subdivided into two biostratigraphic divisions, Cf6γ1 and Cf6γ2, that can be correlated throughout Ireland. Relatively common gigantoproductid brachiopods and the coral Lonsdaleia duplicata occur in the Brigantian units. The base of the Brigantian stage (Cf6δ Subzone) is marked by an increase in the abundance of stellate archaediscids, the presence of Saccamminopsis-rich horizons, Loeblichia paraammonoides, Howchinia bradyana and the rarity of Koninckopora species. Changes in facies at the Cecilstown/Dromdowney Member and the Ballyclogh/Liscarroll Formation boundaries coincide closely with the changes in fossil assemblages that correspond to the early/late Asbian and the Asbian/Brigantian boundaries. These facies changes are believed to reflect major changes in relative sea-level on the Irish platforms. The sea-level variations that are inferred to have caused the facies changes at lithostratigraphic boundaries also brought in the new taxa that define biostratigraphic boundaries. Moreover, many of the Dinantian stage boundaries that are defined biostratigraphically in Great Britain, Belgium and the Russian Platform also coincide with major facies boundaries caused by regressive and transgressive episodes. The integration of detailed biostratigraphic analyses with facies studies will lead to better stratigraphic correlations of Dinantian rocks in northwest Europe. © 1997 John Wiley & Sons, Ltd.     

The upper Viséan–Serpukhovian in the type area for the Serpukhovian Stage (Moscow Basin,Russia): Part 1. Sequences,disconformities, and biostratigraphic summary

The upper Viséan–Serpukhovian strata in the type region for the Serpukhovian Stage is an epeiric‐sea succession ca. 90 m in thickness. The predominantly Viséan Oka Group (comprising the Aleksin, Mikhailov, and Venev formations) is dominated by photozoan packstones with fluvial siliciclastic wedges developed from the west. The Lower Serpukhovian Zaborie Group is composed of the Tarusa and Gurovo formations. The latter is a new name for the shale‐dominated unit of Steshevian Substage age in the studied area. The Zaborie Group is composed of limestones and marls in its lower (Tarusa and basal Gurovo) part and black smectitic to grey palygorskitic shales in the main part of the Gurovo Formation. The Gurovo Formation is capped by a thin limestone with oncoids and a palygorskitic–calcretic palaeosol. The Upper Serpukhovian is composed of a thin (3–12 m) Protva Limestone heavily karstified during a mid‐Carboniferous lowstand. The succession shows a number of unusual sedimentary features, such as a lack of high‐energy facies, shallow‐subtidal marine sediments penetrated by Stigmaria, the inferred atidal to microtidal regime, and palustrine beds composed of saponitic marls. The succession contains many subaerial disconformities characterized by profiles ranging from undercoal solution horizons to palaeokarsts. Incised fluvial channels are reported at two stratigraphic levels to the west of the study area. The deepest incisions developed from the Kholm Disconformity (top of the Mikhailov Formation). This disconformity also exhibits the deepest palaeokarst profile and represents the major hiatus in the Oka–Zaborie succession. The new sea‐level curve presented herein shows two major cycles separated by the Kholm Unconformity at the Mikhailov/Venev boundary. The Lower Serpukhovian transgression moved the base‐level away from falling below the seafloor so that the section becomes conformable above the Forino Disconformity (lower Tarusa). The maximum deepening is interpreted to occur in the lower dark‐shale part of the Gurovo Formation. The base of the Serpukhovian Stage is defined by FADs of the conodont Lochriea ziegleri and the foraminifer Janischewskina delicata in the middle of the sequence VN2. The Aleksinian–Mikhailovian interval is provisionally correlated with the Asbian (Lower–Middle Warnantian) in Western Europe. Based on FODs of Janischewskina typica and first representatives of Climacammina, the Venevian is correlated with the Brigantian in Western Europe. The Tarusian–Protvian interval contains diverse fusulinid and conodont assemblages, but few forms suitable for international correlation. FADs of the zonal conodont species Adetognathus unicornis and Gnathodus bollandensis at several metres above the Protvian base suggest correlation of the entire Zaborie Group and may be the basal Protvian to the Pendleian. Copyright © 2014 John Wiley & Sons, Ltd.     

Stratigraphie et sédimentologie des « calcaires à Productus » du Carbonifère inférieur de la Montagne noire (Massif central,France)Stratigraphy and sedimentology of the Lower Carboniferous ‘Calcaires à Productus’ of the Montagne Noire (Massif Central,France)

The ‘Calcaires à Productus’ of the Montagne Noire are microbial build-ups. Two formations are defined and dated respectively as Uppermost Visean (Upper Warnantian–Brigantian) and Serpukhovian on the basis on corals. That makes these limestones out to be younger than previously stated (Lower and base of Upper Warnantian–Asbian and base of Brigantian) and indicates that the development of the olistoliths and thrusts including them, due to the Variscan orogeny, was at least as young as the Upper Serpukhovian. The Serpukhovian limestones of the Montagne Noire are correlated with the Lanet Limestone (Mouthoumet Massif, Corbières) and Ardengost Limestone (central Pyrenees). To cite this article: É. Poty et al., C. R. Geoscience 334 (2002) 843–848.     

Problems correlating the late Brigantian–Arnsbergian Western European substages within northern England

A detailed study of foraminiferal assemblages recorded in limestones from northern England in the Stainmore Trough and Alston Block permits their assignment to different European substages than in previous studies. Comparisons with foraminiferal assemblages, mostly from Russia, allow the biozonations to be correlated with the Viséan, Serpukhovian and Bashkirian international stages, as well as with the Russian (and Ukrainian) substages for the Serpukhovian (Tarussian, Steshevian, Protvian and Zapaltyubian). The Scar Limestone and Five Yard Limestone Members are assigned to the Tarussian and, thus, represent the lowermost part of the formal Serpukhovian Stage. This new correlation coincides closely with the first occurrence of the conodont Lochriea ziegleri from levels equivalent to the Single Post Limestone that could potentially form the revised base for the Serpukhovian. The Three Yard Limestone Member is correlated with the base of the Steshevian substage which also includes the Four Fathom Limestone Member, Great Limestone Member and Little Limestone. The base of the Protvian is considered to lie within the Crag Limestone, whereas the Rookhope Shell Band contains foraminiferal assemblages more typical of the Zapaltyubian in the Ukraine and Chernyshevkian in the Urals. Assemblages of the Upper Fell Top Limestone and Grindstone/Botany Limestones contain foraminiferal species that have been used for the recognition of the Bashkirian elsewhere. There is no other fossil group which allows the calibration of those foraminiferal assemblages, because ammonoids are virtually absent in the shallow‐water cyclothemic successions and conodonts have not been studied in detail in this region. The Mid‐Carboniferous boundary and the Voznessenian substage might be reasonably located below the Upper Fell Top Limestone. Copyright © 2015 John Wiley & Sons, Ltd.     

Stratigraphy of upper Viséan carbonate platform rocks in the Carlow area,southeast Ireland

The stratigraphy of the upper Viséan (Asbian to Brigantian) carbonate succession in southeast Ireland is revised on the basis of seven quarry and two borehole sections. Six lithological units have been distinguished, two units (units 1 and 2) in the upper Asbian Ballyadams Formation, and four units (units 4 to 6) in the Brigantian Clogrenan Formation (both formations are dated precisely using foraminiferans, calcareous algae and rugose corals). The boundary between the Ballyadams and Clogrenan formations is redefined 19 m below the horizon proposed by the Geological Survey of Ireland, and thus, lithological characteristics of both formations are redescribed. The upper part of the Ballyadams Formation is characterized by well‐developed large‐scale cyclicity, with common subaerial exposure surfaces. Fine‐ to medium‐grained thin‐bedded limestones with thin shales occur in the lower part of cycles, passing up into medium‐grained pale grey massive limestones in the upper part. The Clogrenan Formation is composed mainly of medium‐ to coarse‐grained thick limestone beds with variable presence of shales; but no large‐scale cyclicity. There is a decrease in the number of subaerial exposure surfaces towards the top of the formation and common chert nodules; macrofauna occurs mostly concentrated in bands. The six units recognized in the Carlow area are comparable with other units described for the same time interval (Asbian–Brigantian) from south and southwest Ireland, demonstrating the existence of a stable platform for most parts of southern Ireland, controlled principally by glacioeustatics. Copyright © 2004 John Wiley & Sons, Ltd.     

Biostratigraphy of Dinantian limestones and associated volcanic rocks in the Limerick Syncline,Ireland

Rocks of Courceyan to Brigantian age are exposed in the Limerick Syncline. However, a complete Courceyan succession is known only from two boreholes which correlate closely, both faunally and lithologically, with a standard Limerick Province succession in the Pallaskenry Borehole on the Shannon estuary. This is followed by a thick Waulsortian sequence (the newly defined Limerick Limestone Formation) of late Courceyan to early Chadian age and overlying cherty micrites (the newly defined Lough Gur Formation) of early to late Chadian age, whose top is younger to the east. The Lough Gur Formation is succeeded by lavas and tuffs of the Knockroe Volcanic Formation whose upper part is interbedded with and overlain by shallow water oolites and algal-rich bioclastic limestones of the Herbertstown Limestone Formation. The higher part of the latter is in turn interbedded with lavas and tuffs of the Knockseefin Volcanic Formation. The Herbertstown Limestone has rich and diverse coral/brachiopod and foraminiferal assemblages of late Chadian to Asbian age. Its base is markedly diachronous: late Chadian in the west of the syncline and Holkerian in the east. Both the base and top of the Knockroe Volcanic Formation are thus shown to be markedly diachronous and volcanism extends from the Chadian to early Asbian. The Knockseefin Volcanic Formation is entirely of Asbian age. The highest limestones (Dromkeen Limestone Formation) have a diagnostic late Asbian–early Brigantian fauna and are overstepped by mid-Namurian shales.     

Les séries du carbonifère inférieur de la région d''Adarouch, NE du Maroc central: lithologie et biostratigraphie

The early Carboniferous series of the Adarouch area (northeast central Morocco) are subdivided into three sedimentological and biostratigraphical units. The first unit, which belongs to the Late Visean zones V3bβ and V3bγ, was deposited on shallow carbonate platforms. The second unit belongs to the Late Visean zone, V3c, and incudes terrigenous deposits, such as turbidites, shales and olistostromes. The third unit belongs to the Serpukhovian stage and consists of sandstones and limestones. A new biostratigraphical analysis, which is based on foraminiferal, algae and pseudoalgae, allows an accurate dating of the units. The deposits of the zones V3bβ and V3bγ contain characteristic calcareous microfossils, such as Stacheoides sp., Pseudoendothyra sp. and Ungdarella uralica. The V3c zone (300–400 m) is shown in two oolitic beds of the Mouarhaz and Akerchi Formations, respectively, with Janischewskina sp. and Asteroarchaediscus sp. The Serpukhovian stage is characterised by the disappearance of the algae Koninckopora and the appearance of the brachiopod Titanaria. The new data from the Adarouch area confirm the Moroccan biostratigraphical scale of the Moroccan meseta.     

A candidate for the Global Stratotype Section and Point at the base of the Serpukhovian in the South Urals,Russia

The Verkhnyaya Kardailovka section is one of the best candidates for the GSSP (Global Stratotype Section and Point) at the base of the Stage (Mississippian). For boundary definition, the first appearance of the conodont Lochriea ziegleri Nemirovskaya, Perret et Meischner, 1994 in the lineage Lochriea nodosa (Bischoff, 1957)?L. ziegleri is used. L. ziegleri appears in the Venevian Substage somewhat below the base of the Serpukhovian in the Moscow Basin. The position of the FAD of L. ziegleri within the Hypergoniatites?Ferganoceras Genozone is confirmed and lies between 19.53 and 19.63 m above the section’s base. Before 2010, deep-water stylonodular limestone containing the boundary in unnamed formation C at Kardailovka was well exposed but only 3 m of Viséan strata cropped out immediately below. Recent trenching exposed another 10 m of underlying Viséan carbonates in formation C and older Viséan siliciclastics and volcanics in unnamed formation B. The contact between formation B and underlying crinoidal limestones in unnamed formation A representing the middle Viséan Zhukovian (Tulian) regional Substage was excavated. The boundary succession, situated in the Magnitogorsk tectonic zone above the Devonian Magnitogorsk arc and Mississippian magmatic and sedimentary rift succession, was deposited west of the Kazakhstanian continent during closure of the Ural Ocean. In the lower part of the section, Viséan tuffaceous siliciclastics and volcanics of formation B record rapid deepening after deposition of neritic middle Viséan crinoid lime grainstone of formation A and subsequent subaerial exposure. The overlying condensed upper Viséan to Serpukhovian succession in formation C comprises deep-water limestone deposited in a sediment-starved basin recording minor turbidite influx and carbonate-mound development. The δ¹³C_carb plot shows a positive shift of 1‰ V-PDB (from +2 to +3‰) between 17.0 and 17.75 m (3.05 and 1.97 m below FAD L. ziegleri). The δ¹⁸O_apatite graph displays a prominent upward shift from 19.9 to 21.1‰ V-SMOW (at 19.15 to 19.51 m) in the nodosa Zone below FAD of Lochriea ziegleri.     

Foraminifers and conodonts from the late Viséan to early Bashkirian succession in the Saharan Tindouf Basin (southern Morocco): biostratigraphic refinements and implications for correlations in the western Palaeotethys

The Carboniferous succession in the Tindouf Basin of southern Morocco, North Africa, displays Mississippian to Early Pennsylvanian marine beds, followed by Pennsylvanian continental deposits. The marine beds comprise a shallow water cyclic platform sequence, dominated by shales and fine‐grained sandstones with thin but laterally persistent limestone/dolostone beds. Foraminiferal assemblages have been studied in the limestone beds in several sections from the Djebel Ouarkziz range in the northern limb of the Tindouf Syncline; they indicate that the age of the limestones range from late Asbian (late Viséan) to Krasnopolyanian (early Bashkirian). The foraminiferal assemblages are abundant and diverse, and much richer in diversity than those suggested by previous studies in the region, as well as for other areas of the western Palaeotethys. The richest assemblages are recorded in the Serpukhovian but, unusually, they contain several taxa which appear much earlier in Western European basins (in the latest Viséan). In contrast, conodont assemblages are scarce due to the shallow‐water facies, although some important taxa are recorded in the youngest limestones. Copyright © 2013 John Wiley & Sons, Ltd.     

The recognition of the Asbian/Brigantian boundary fauna and marker horizons in the Dinantian of North Wales

For the first time the stratigraphically important brachiopod Davidsonina septosa (Phillips) has been located in thickly bedded pale grey, late Asbian limestones in North Wales. Above these limestones are thinly bedded dark grey Brigantian limestones, which have yielded a rich and diverse coral-brachiopod fauna, including Lonsdaleia floriformis (Martin). The Girvanella Nodular Bed is recorded for the first time in this region, some distance above the base of the Brigantian. The boundary between the two major lithofacies is marked by a prominent palaeokarstic surface and coincides with a significant faunal change, both in the macrofauna and microfauna that serves to identify the boundary between the Asbian and Brigantian Stages. The discovery within late Dinantian successions of certain diagnostic corals, brachiopods, and algae outside their accepted restricted stratigraphical ranges, casts doubt on their reliable use as Asbian or Brigantian zone fossils.     

A reassessment of Arundian–Holkerian (Viséan) carbonates in South Cumbria,UK

Despite the importance of south Cumbrian sections for the Arundian–Holkerian (mid Viséan) boundary, beyond the stratotype proposed at Barker Scar in 1976, little else is known regionally about this boundary and its relationship to adjacent formations. We re-evaluate the Dalton Formation, making its upper and lower boundaries regionally more consistent and precisely-defined, in good quality outcrops with associated biostratigraphy. The Dalton Formation is formally divided into the Blackstone Member and overlying Raven's Member. Rich foraminiferal assemblages of the Cf4δ subzone are recognized in the Blackstone Member and the lower to mid Raven's Member in nine sections. The Cf4γ–Cf4δ boundary is recognized in the underlying Red Hill Limestone Formation in 3 sections. The upper part of the Raven's Member shows the first appearance of taxa assigned to the Cf5α and Cf5β subzones of the Holkerian in three of the sections. Bentonitic shales in the mid and upper-most part of the Raven's Member were evaluated for zircon and apatite geochronology, although only 4 out of 504 analyses yielded Carboniferous ages, indicating an almost entirely detrital source. This detritus was northerly or northeasterly-derived and predominantly from the Southern Uplands Terrane with subsidiary input from the Lewisian Complex or eastern Greenland sources. Petrographic analysis identified 13 microfacies indicating that the Dalton Formation represents the inner to outer part of a southward inclined shelf, in which east–west changes in microfacies were generated by synsedimentary faulting inherited from northwest–southeast aligned basement structures.     

Stratigraphy and sedimentology of lower carboniferous (Dinantian) boreholes from West Co. Meath,Ireland

The 2-km deep Athboy Borehole (1439/2) together with the lower part of boreholes EP30 and N915 form a standard type section for strata of Dinantian (Courceyan to Asbian) age in west Co. Meath. Above a thin basal red-bed siliciclastic sequence, the marine Courceyan shelf succession is almost 600 m thick. It comprises the Liscartan, Meath, and Moathill Formations of the Navan Group and the Slane Castle Formation of the succeeding Boyne Group. The shallow-water limestones include micrites, oolites, and sandy bioclastic packstones and grainstones with subordinate skeletal wackestones and shales. Lateral facies changes from north to south in the Navan area suggest deepening across a shelf towards a depocentre further to the south around Trim. The deeper-water Waulsortian Limestones of late Courceyan to Chadian age (Feltrim Formation, ca. 213 m thick) form a series of five sheet-like mudbanks, interbedded with generally thin units of nodular crinoidal limestones and shales. The mudbanks are formed of bryozoan-rich peloidal wackestones and lime-mudstones with phase C and D components. Rare soft-sediment breccias occur at the bottom and top of banks. The succeeding Fingal Group commences with a thin interval (3–20 m) of black shales, laminated packstones, and micritic limestones of Chadian age, the Tober Colleen Formation. This is followed by the Lucan Formation (Chadian to Asbian) predominantly of laminated and graded calciturbidites, laminated sandstones, cherts, and black shales, which is over 1300 m thick. Ten sedimentary units have been informally defined, based on lithofacies and facies associations. The oldest unit, the Tara Member, is characterized by proximal debris-flow breccia deposits and nodular mudstones. A thick bioturbated micrite and shale unit (Ardmulchan Member) in the middle of the formation is overlain directly by a coarse oolitic and crinoidal grainstone unit (Beauparc Member). Near the top of the formation is a distinctive unit of coarse-grained laminated sandstones and shales (Athboy Member). The highest rocks in the Borehole are clean thickly-bedded limestones of the Asbian Naul Formation (>90 m thick). The youngest Dinantian strata in the area, the Brigantian Loughshinny Formation, marks a return to shale-dominant basin sedimentation. The significance of this work lies in the fact that the Athboy borehole is the longest continuously cored borehole in the Carboniferous of Ireland and provides a continuous sedimentary and biostratigraphic record for the northern part of the Dublin Basin. Foraminiferal biozones (Cf2–Cf6) have been recognized in this and in borehole N915, and Stage boundaries identified, which can be applied throughout the Basin. The sedimentary record for the Lucan Formation indicates four tectonic pulses during the Viséan, in the late Chadian/early Arundian, mid-Arundian, Holkerian, and late Holkerian/early Asbian.     

Lower carboniferous (Dinantian) stratigraphy and structure in the Kingscourt Outlier,Ireland

Logging of 55 recent boreholes, together with remapping, has resulted in a fundamental reassessment of the stratigraphy and sedimentology of the Dinantian Kingscourt Outlier. Despite the present isolated position of the outlier within the Longford-Down Massif, the Kingscourt rocks are an integral part of the Dublin Basin succession. The newly defined Ardagh Platform marks the most northerly limit to basinal sedimentation in the Dinantian Dublin Basin. The Courceyan is a typical but thinner, north Dublin Basin succession with two new formal units: the Rockfield Sandstone Member and the Kilbride Formation. The latter, a coarse-grained, well washed limestone of latest Courceyan to early Chadian (late Tournaisian) age is the shallow water equivalent of the Feltrim Formation (Waulsortian facies), which is absent in the outlier. The Courceyan interval in the north of the outlier is markedly attenuated. In the succeeding Chadian-Brigantian interval basinal facies predominate in the south, but on the Ardagh Platform an almost complete coeval Viséan shallow water sequence is found. A new platform unit (Deer Park Formation) of latest Asbian to Brigantian age is defined in the Ardagh area. The Dee Member (Chadian) is newly defined for the lower part of the basinal Tober Colleen Formation and the Altmush Shale Member is formally defined for the upper part of the Loughshinny Formation. Two major structures dominate the Kingscourt Outlier: the NE-SW trending Moynalty Syncline in the south and the N-S trending Kingscourt Fault. Both are Hercynian structures, but probably represent reactivated Caledonide basement-controlled structures. Dinantian syn-depositional faulting is indicated in both the Courceyan (‘Kingscourt Sag’) and Chadian-Asbian. The latter period of faulting in the Ardagh area separates platform facies in the north from basinal facies to the south. In the late Asbian, platform facies with carbonate build-ups prograded south into the basin as far south as Nobber, but in the latest Asbian to Brigantian, basinal facies extended northwards over the collapsed platform margin.     

A SIMS zircon age for a biostratigraphically dated Upper Viséan (Asbian) bentonite in the Central-European Variscides (Bardo Unit,Polish Sudetes)

A Lower Carboniferous platform sedimentary sequence (the Paprotnia Beds) in the Bardo Unit of the central Sudetes (NE part of the Bohemian Massif, SW Poland) is biostratigraphically well dated, based on rich macro- and micro-fossil evidence, as Late Viséan (late Asbian, crenistria, Go III α zone). The beds contain several bentonite layers, one of which was dated using the U–Pb SHRIMP method on volcanic zircons and yielded an age of 334 ± 3 Ma. This date fits well to the recently established chronostratigraphic limits of the Viséan, and is consistent with the newest isotopic age constraints of 336.5–332 Ma for the Asbian boundaries.     

The upper Volgian Substage in Northeast Siberia (Nordvik Peninsula) and its Panboreal correlation based on ammonites

Section of the middle and upper Volgian substages and basal Boreal Berriasian in the Cape Urdyuk-Khaya (Nordvik Peninsula) is largely composed of dark argillites substantially enriched in C_org. Characteristic of the section is a continuous succession of ammonite, foraminiferal, ostracode, and dinocyst zones known also in the other Arctic areas. Boundaries of the upper Volgian Substage are recognizable only based on biostratigraphic criteria. The succession of the middle Volgian Taimyrosphinctes excentricus to basal Ryazanian Hectoroceras kochi zones is characterized. The range of the substage is revised. The lower Exoticus Zone, where ammonites characteristic of the Nikitini Zone upper part in the East European platform have been found, is referred to the middle Volgian Substage. Newly found ammonites are figured. Two possible positions of the Jurassic-Cretaceous boundary in the Arctic region, i.e., at the lower and upper boundaries of the Chetae Zone at the top of the upper Volgian Substage, are discussed.     

The shark-beds of the Eyam Limestone Formation (Lower Carboniferous,Viséan) of Steeplehouse Quarry,Wirksworth, Derbyshire,UK

The Eyam Limestone Formation of Steeplehouse Quarry, Wirksworth, Derbyshire, UK yields a diverse assemblage of Lower Carboniferous vertebrate remains. The assemblage is dominated by dermal denticles of the enigmatic selachian Petrodus patelliformis M’Coy, 1848, but also contains teeth of petalodonts, hybodonts and neoselachians. Actinopterygian remains also occur. The assemblage has yielded the earliest Neoselachian, Cooleyella fordi (Duffin and Ward, 1983) and the earliest British lonchidiid, Reesodus wirksworthensis (Duffin 1985). The first occurrence of the enigmatic spiny shark Acanthorhachis (Listracanthidae) is reported from the Viséan, extending its range back some 10 million years. Associated invertebrate remains and sedimentological data indicates a thriving fore-reef environment, deposited in a low energy off-reef setting. The vertebrate remains are well preserved with little abrasion, indicating short transport distances. Conodont elements indicating a late Brigantian age (Early Carboniferous, Viséan) have unusual and extensive euhedral apatite overgrowths.     

Planktic foraminiferal and 13C isotopic changes across the Paleocene/Eocene boundary at Possagno (Italy)

 The interval spanning the Paleocene–Eocene (P/E) transition in the Possagno section consists of 1 m of red marls, including a 4-cm-thick, dark-red "dissolution" clay, which represents the Paleocene/Eocene boundary event. The Possagno section is much more condensed than other Tethyan and North Atlantic sections previously studied; however, in this section the most significant biotic, isotopic and sedimentological events across the P/E boundary can be recognized. The Possagno section spans the following planktic foraminiferal subzones: upper part of M. gracilis Subzone, A. berggreni Subzone, A. sibaiyaensis Subzone and probably lowermost part of P. wilcoxensis Subzone. The quantitative analysis indicates a major increase of low-latitude acarininids, including compressed tropical acarininids just above the boundary clay. This acarininid incursion begins just below the boundary clay but reaches its maximum just above the clay. The planktic foraminiferal faunal turnover is gradual except for the acarininid incursion. The isotopic results show a negative excursion in ∂¹³C values at the small benthic foraminifera mass extinction event. The acarininid maximum diversity coincides with this isotopic excursion, and reflects an increase in surface seawater temperature. Despite being very condensed, the Possagno section allows us to further confirm that the different biotic, isotopic and sedimentological events recognized in the Spanish sections (Alamedilla, Campo, Caravaca, Zumaya) are not local in nature and allows the establishment of a detailed chronostratigraphic framework to define the P/E boundary stratotype. Received: 8 April 1998 / Accepted: 12 April 1999     

Early Serpukhovian (late Mississippian) microflora from the Guadiato Area (southwestern Spain)

Calcareous microflora occur commonly in the early Serpukhovian (late Mississippian) rocks from the Guadiato Area (southwestern Spain) despite the fact that this area contains mostly siliciclastic sediments. The microflora recorded in the carbonate beds is regarded as representative of both relatively deep‐water and shallow‐water facies and can be compared with the slope and shelf facies environments distinguished in the Guadiato Area. Up to 45 algal taxa have been identified in the carbonate beds, of which 26 taxa occur in the relatively deep‐water assemblages, whereas the shallow‐water assemblages are composed of up to 43 taxa. The entire algal assemblage is dominated by calcifoliids, common cyanobacteria and incertae sedis, but the shallow‐water assemblages contain more commonly dasyclads, red algae and aoujgaliids. Most of these taxa are present, but poorly known, in other Serpukhovian carbonate platforms in the western Palaeotethys. Some algae (Hortonella uttingii, Kamaenella tenuis and Koninckopora inflata), usually regarded as being restricted to the Viséan, have been found in Serpukhovian rocks in the Guadiato Area, and also in Algeria, thus their stratigraphic ranges might be extended up to the Serpukhovian. Other important taxa include: Archaeolithophyllum, Cabrieropora, Calcifolium, Falsocalcifolium, Fourstonella, Frustulata, Kulikia, Neoprincipia and ‘Windsoporella’, which are exceptionally recorded in Serpukhovian rocks, or not recorded at all, because they are typically recorded in the Pennsylvanian (cf. Clavaporella), although some of them show earlier occurrences in Viséan rocks (Claracrusta, Paraepimastopora and Sparaphralysia). Some of the algal taxa can be considered as potential regional markers for the Serpukhovian, such as Archaeolithophyllum, cf. Clavaporella, Frustulata and Girvanella (?) sp. The algal assemblages found in the Guadiato Area show the greatest similarities with those in the Béchar‐Mézarif (Algeria), Pyrenees and Montagne Noire (southern France). Copyright © 2005 John Wiley & Sons, Ltd.