ABSTRACT The presence of archaeocyath-bearing clasts from Cenozoic tills and Cambrian Mount Wegener Formation reveal erosion of a hidden Cambrian carbonate platform in Shackleton Range, Antarctica. We provide microfacies, paleontological, diagenetic and tectonically induced fabric data from carbonate clasts which, in addition to available geochemical and geochronological data from Shackleton Range, allow the paleoenvironmental reconstruction of a lost Cambrian Series 2 mixed siliciclastic–carbonate platform that was developed and eroded during the Ross orogeny. Carbonate production was dominated by non-skeletal grains in possibly restricted platform-interior and oolitic shoal complex settings, while open subtidal sub-environments (calcimicrobe carpets, calcimicrobe–archaeocyath patch reefs, muddy bottoms) were dominated by a diverse calcimicrobe assemblage and/or by secondary to accessory heterozoan assemblage (archaeocyaths and other sponges, chancelloriids, hyoliths, coralomorphs, trilobites, echinoderms). We describe a Botoman assemblage with 34 archaeocyathan species among 12 existing archaeocyathan genera. A new archaeocyath family Shackletoncyathidae is proposed. New species ( Rotundocyathus glacius sp. nov., Buggischicyathus microporus gen. et sp. nov., Paragnaltacyathus hoeflei , Shackletoncyathus buggischi gen. et. sp. nov., Santelmocyathus santelmoi gen. et sp. nov., Wegenercyathus sexangulae gen. et sp. nov.) and Tabulaconus kordae coralomorph are reported from Antarctica for the first time. Archaeocyathan fauna share few species with contemporary fauna of South Australia (9) and even fewer with the Antarctic platforms of the Shackleton Limestone (2) or the Schneider Hills limestone (1). Similarity is greater with Antarctic allochthonous assemblages of Permo-Carboniferous tillites from Ellsworth Mountains (2), Cenozoic deposits from King George Island (4) or Weddell Sea (1). The Shackleton Range lost/hidden platform shows a distinct entity related with its tectonosedimentary evolution, in a possible back-arc basin on the Mozambique seaway during the E and W Gondwana amalgamation, which distinguishes it from those developed on the palaeo-Pacific margin of the E Antarctic craton.

Based on seven measured sections from Svalbard, the marine strata of the Permian Kapp Starostin Formation are arranged into seven transgressive-regressive sequences (TR1-TR7) of c. 4-5 Ma average duration, each bound by a maximum regressive surface. Facies, including heterozoan-dominated limestones, spiculitic cherts, sandstones, siltstones and shales, record deposition within inner, middle and outer shelf areas. The lowermost sequence, TR1, comprises most of the basal Voringen Member, which records a transgression across the Gipshuken Formation following a hiatus of unknown duration. Temperate to cold, storm-dominated facies established in inner to middle shelf areas between the latest Artinskian and Kungurian. Prolonged deepening during sequences TR2 and TR3 was succeeded by a long-term shallowing-upward trend that lasted until the latest Permian (TR4-TR7). A major depocentre existed in central and western Spitsbergen while to the north, Dickson Land remained a shallow platform, leading to a shallow homoclinal ramp in NE Spitsbergen and Nordaustlandet. The Middle Permian extinction (late Capitanian) is recorded near the base of TR6 in deeper parts of the basin only; elsewhere this sequence is not recorded. Likewise the youngest sequence, TR7, extending to the upper formational contact of latest Permian age, is found only in the basin depocentre. Comparison with age-equivalent strata in the Sverdrup Basin of Canada reveals a remarkably similar depositional history, with, for example, two (third-order) sea-level cycles recorded in the Late Permian of both regions, in keeping with the global record. Sequence stratigraphy may therefore be a powerful correlative tool for onshore and offshore Permian deposits across NW Pangaea.

An integrated study of the litho-, bio-, and isotope stratigraphy of carbonates in the Southern Alps was undertaken in order to better constrain δ13C variations during the Late Carboniferous to Late Permian. The presented high resolution isotope curves are based on 1299 δ13Ccarb and 396 δ13Corg analyses. The carbon isotope record of diagenetically unaltered samples from the Carnic Alps (Austria) and Karavanke Mountains (Slovenia) shows generally high δ13C values, but Late Carboniferous and Early Permian successions are affected by a diagenetic alteration as consequence of glacio-eustatic sea level changes. Negative δ13C excursions are related to low-stand deposits and caused by diagenetic processes during subaerial exposure. The comparison with δ13C records from other parts of the world demonstrate that δ13C values are high in most unaltered samples, an overall negative trend during the Permian, as recently published, is not obvious and negative excursions related to changes in the carbon isotope composition of the global oceanic carbon pool cannot be confirmed, except for the Permian–Triassic boundary interval.

An about 215 m thick sedimentary sequence of the Early Permian Gipshuken Formation was measured at Talmodryggen in central Spitsbergen. The sequence consists of predominantly several metres thick gypsum deposits at the base, overlain by metre thick cyclic dolomite/gypsum alternations, followed by mainly laminated dolomites with intercalated layers of dolomitic marls, gypsum and ooids. The sediments are interpreted to represent deposits of salinas, sabkha cycles and shallow marine (lagoonal) environments. Stable carbon isotopes in the lower part of the Gipshuken Formation exhibit delta C-13 values similar to those known from open marine settings indicating that early diagenesis and dolomitisation took place in marine derived pore water solution. Distinctly lowered delta C-13 values in the upper Gipshuken Formation point to an influence of remineralisation of organic carbon and lower delta C-13(DIC) during diagenesis. The change in diagenesis may possibly be ascribed to a change from arid to slightly more humid conditions.

Oxygen isotopes measured on Late Ordovician conodonts from Minnesota and Kentucky (United States) were studied to reconstruct the paleotemperature history during late Sandbian to Katian (Mohawkian-Cincinnatian) time. This time interval was characterized by intense volcanism, as shown by the prominent Deicke, Millbrig, and other K-bentonite beds. A prominent carbon isotope excursion (Guttenberg delta C-13 excursion, GICE) postdates the Millbrig volcanic eruptions, and has been interpreted to reflect a drawdown of atmospheric carbon dioxide and climatic cooling. The oxygen isotope record in conodont apatite contradicts this earlier interpretation. An increase in delta O-18 of 1.5% (Vienna standard mean ocean water) just above the Deicke K-bentonite suggests an abrupt and short-lived cooling that possibly initiated a first short-term glacial episode well before the major Hirnantian glaciation. The decrease in delta O-18 immediately after the mega-eruptions indicates warming before the GICE, and no cooling is shown in the GICE interval. The coincidence of the Deicke mega-eruption with a cooling event suggests that this major volcanic event had a profound effect on Late Ordovician (late Mohawkian) climate.

The Pennsylvanian and Early Permian were times of extreme sea-level changes of >100 to perhaps up to 200m. For example, glacio-eustatic sea-level changes are well documented from the US Midcontinent, Moscow Basin and Yangtze Platform, where more than 100 stacked subtidal to supratidal sequences have been described. In contrast, carbonates developed in the Ural Mountains and South Guizhou of the Yangtze Platform were deposited in ramp and slope settings. δ13C values of whole rock samples from the US Midcontinent and Moscow Basin were intensively affected by diagenesis. Only well-preserved brachiopod shells maintained their original carbon isotope ratios. In contrast, limestones deposited in the deeper water slope environments were not affected by meteoric diagenesis and are interpreted to have mainly retained their carbon isotope ratios. Mean δ13C values of slope carbonates of the Yangtze Platform increase from about 3‰ during the Viséan and Serpukhovian to 5‰ at the Carboniferous–Permian boundary and decrease to values around 2‰ in the early Kungurian. This positive δ13C excursion coincides with low δ13C values in the Yangtze Platform successions, which were reset by meteoric diagenesis. The highest δ13C values recorded in the slope succession coincide with the inferred maximum glaciation that caused pronounced sea-level lowstands. Short-lived, but significant negative δ13C excursions in the Chinese slope succession are interpreted to reflect changes in ocean circulation due to sea-level rises which caused enhanced production and/or preservation of organic matter which influenced the subsequent early diagenetic cementation.

The metamorphic grade and the facies of the Neoproterozoic Malmesbury Group of the Saldania Fold Belt changes abruptly across major fault zones. Therefore three different tectonostratigraphic domains were assumed: The Tygerberg Terrane, the Swartland Terrane and the Boland Terrane. Additionally, a small block with volcanic greenstones and carbonates (Bridgetown Formation) is squeezed between the Swartland and Boland terranes. Based on the investigations of sedimentray and tectonic structures, geochemistry and data from literature, a geodynamic model of the Saldania Belt is proposed including: (1) An ocean between South America with the attached Tygerberg Terrane and the Swartland Terrane, (2) rifting between the Swartland Terrane and South Africa with the attached Boland Terrane, subduction ot the ocean (1) towards west, followed by subduction of the ocean (2) underneath the Swartland Terrane.

Geochemical analyses from Late Proterozoic - Early Cambrian elastic metasediments of the Sierras Norte de Cordoba, Sierras Grandes de Cordoba and Sierra de Guasayan (western Argentina) show a wide spread from arkoses over litharenites and wackes to shales, and partly greywackes. Discriminant function diagrams suggest a felsic igneous and quartzose sedimentary provenance for the sediments of the Lower and Upper Unit in the Sierras Norte de Cordoba, respectively, and a quartzose provenance for those in both other areas. The analyses record a weak weathering suggesting short sedimentary transports. Major element diagrams suggest passive and partly active continental margins for the Sierras Norte and an active continental margin with an overlap to the passive margin for the Sierras Grandes de Cordoba/Guasayin. The trace element diagrams do not indicate a setting of the Upper Unit samples in an active margin. They show that the Lower Unit was dominated by recycling of acidic continental crustal material whereas the other sediments point to the influence of old sediment components. Also, in view of the rare earth element diagrams, a setting of the Lower and Upper Unit on a passive margin is probable. With its elastic content derived from local elastic and magmatic rocks, the Lower Unit probably was covered by the Upper Unit deposited in a shelf area that received elastic and magmatic detritus also from a hinterland in the east. Sedimentary transports into a wide Puncoviscana basin in the west are according to the situation in northwest Argentina and have an equivalent in the Antarctic area of the later-formed Ross orogen. This suggests a comparable passive margin development at the paleo-Pacific side of Gondwana in the South American (Pampean) and Transantarctic (Ross) sectors, with sedimentary transports from inner Gondwanan cratonic areas during the Late Proterozoic - Early Cambrian times.

Carbon isotopes of whole rock carbonates and oxygen isotopes of conodont apatite from Late Devonian to Early Pennsylvanian sections in Europe and Laurentia were measured in order to reconstruct variations in the carbon cycle, marine palaeotemperature, and ice volume during the Mississippian. Conodont apatite δ18O values show two major positive shifts of + 2‰ and + 1.5‰ V-SMOW in the late Tournaisian and Serpukhovian, respectively, that are interpreted to reflect climatic cooling and changes in ice volume. Carbon isotope ratios of inorganic and organic carbon show a major positive excursion with an amplitude of + 6.5‰ V-PDB in the Tournaisian and a positive shift of up to + 5‰ V-PDB in the Serpukhovian. The positive δ13C excursions coincide with the deposition of organic carbon-rich black shales which indicate that organic carbon burial, lowering of atmospheric pCO2, and climatic cooling may have occurred during these time intervals. However, while in the Tournaisian the positive shifts in δ18Oapatite and δ13C coincide, in the Serpukhovian the positive shift in δ18Oapatite precedes the positive shift in δ13C and raises the question as to whether changes in the global carbon cycle were the ultimate cause of the inferred climatic changes. The conodont apatite δ18O values suggest that a first major cooling and potential glaciation event occurred in the Tournaisian with ice masses persisting into the Visean. The second glaciation event occurred in the Serpukhovian and culminated in the first glacial maximum of the Late Palaeozoic Glaciation.

Carbon isotopes of whole rock carbonates and oxygen isotopes of conodont apatite from Late Devonian to Early Pennsylvanian sections in Europe and Laurentia were measured in order to reconstruct variations in the carbon cycle, marine palaeotemperature, and ice volume during the Mississippian. Conodont apatite delta O-18 values show two major positive shifts of +2 parts per thousand and +1.5 parts per thousand V-SMOW in the late Tournaisian and Serpukhovian, respectively, that are interpreted to reflect climatic cooling and changes in ice volume. Carbon isotope ratios of inorganic and organic carbon show a major positive excursion with an amplitude of +6.5 parts per thousand. V-PDB in the Tournaisian and a positive shift of up to +5 parts per thousand V-PDB in the Serpukhovian. The positive delta C-13 excursions coincide with the deposition of organic carbon-rich black shales which indicate that organic carbon burial, lowering of atmospheric PCO2, and climatic cooling may have occurred during these time intervals. However, while in the Tournaisian the positive shifts in delta O-18(apatite) and delta C-13 coincide, in the Serpukhovian the positive shift in delta O-18(apatite) precedes the positive shift in delta C-13 and raises the question as to whether changes in the global carbon cycle were the ultimate cause of the inferred climatic changes. The conodont apatite delta O-18 values suggest that a first major cooling and potential glaciation event occurred in the Tournaisian with ice masses persisting into the Visean. The second glaciation event occurred in the Serpukhovian and culminated in the first glacial maximum of the Late Palaeozoic Glaciation. (c) 2008 Elsevier B.V. All rights reserved.

A model of global biogeochemical cycles coupled to an energy-balance climatic model (modified after the COMBINE model; [Godderis, Y., Joachimski, M.M., 2004. Global change in the Late Devonian: modeling the Frasnian-Famennian short-term carbon isotope excursions. Palaeogeogr. Palaeoclimatol. Palaeoecol. 202, 309-329]) is used to calculate the short-term evolution of atmospheric pCO(2) during the Devonian. The geochemical cycles for carbon, alkalinity, phosphorus, sulfur and oxygen are included in this model, with also 13 C and S-34 cycles. High-resolution records of delta C-13 of marine carbonates and delta S-34 of marine sulfates are used as forcing parameters of the geochemical cycles in an inverse modeling. Atmospheric pCO(2) and pO(2) at the end of the Silurian are calculated to have been 3000 ppmv and 0.165 bar (0.75 PAL), respectively. A long-term decrease in pCO(2) is modeled for almost the entire Devonian. Short-term lowering Of pCO(2) to concentrations around 2000 ppmv is calculated for the Silurian-Devonian transition and the Pragian. Contents around 900 ppmv are modeled for the Eifelian-Givetian, Givetian-Frasnian and Frasnian-Famennian boundaries as a consequence of enhanced organic carbon burial during deposition of Lochkovian, Eifelian, and Frasnian grey and black shales. Organic carbon burial is enhanced by the increase of phosphorus delivery to the ocean triggered by short-term sea-level falls. The corresponding short-term global climatic cooling at the Silurian-Devonian boundary, at the end of the Pragian, and the Givetian-Frasnian as well as Frasnian-Famennian boundaries reached 2 degrees C at the equator. The rapid colonization of continental surface by land plants during the Middle and Late Devonian, increasing chemical alteration of the continents and CO2 consumption by silicate weathering, is assumed to have caused cooling of surface seawater, as suggested by the delta O-18 values of biogenic apatites. (c) 2007 Elsevier B.V. All rights reserved.

During the late Silurian the Prague Basin was located in middle southern latitudes. In contrast to palaeocontinents positioned in tropical and subtropical latitudes like Baltica, no reefs are developed, which is in accordance with the predicted cooler water. The Prague Basin represents a relatively restricted and shallow rift basin with a complex tectonic history. Sections in different palaeoenvironments have been studied to document the most prominent Silurian stable carbon isotope excursion recorded during the late Silurian (Ludfordian) Lau Event from this part of peri-Gondwana. Deeper water deposits of the Kopanina Formation investigated in the present study were deposited on the slope-to-basin transition near the Kosov volcanic centre in the western part of Prague Basin. The sediments are developed as an alternation of dark, partly laminated limestones and marls with an increase of the limestone–marl ratio in the upper part of the succession. A pronounced positive carbon isotope excursion starts in the Neocullograptus kozlowskii graptolite and in the upper Polygnathoides siluricus conodont zone. The maximum of the shift is observed in the lower part of an interval characterised by the Ananaspis fecunda–Cyrthia postera community. The maximum values scatter around 8‰, which represent the highest values reported hitherto from the Prague Basin. In low latitudes, often a decrease of δ13C values towards deeper water settings is reported. In contrast, in the present study the δ13C values of about 8‰ are much higher than those recorded from the contemporaneous shallow-water sections studied in the classical Mušlovka and Požáry quarries. The most reasonable explanation is the presence of stratigraphical gaps in the shallow parts of the basin. As indicated by karstification these gaps were caused by a sea-level drop. Another effect of this sea-level fall was a strongly reduced sedimentation of the cephalopod limestone facies around volcanic and tectonic elevations.

Carbonate rocks of the Rhenohercynian and Saxothuringian zones of the Variscan Mountains, Prague Syncline, Carnic Alps, Montagne Noire, Pyrenees, and Cantabrian Mountains were investigated for δ13Ccarb. The values were measured on bulk carbonate, selected carbonate components and cements. Many of the studied carbonates are interpreted to exhibit primary marine δ13C values with only some showing evidence of diagenetic alteration. A δ13C curve is presented for the entire Devonian time interval. Positive δ13C excursions are documented in the woschmidti-postwoschmidti, sulcatus, kitabicus, Upper serotinus, kockelianus, Middle varcus, falsiovalis, Upper rhenana, linguiformis to Middle triangularis, and Middle to Upper praesulcata conodont Zones. Some excursions are recorded worldwide and interpreted to be of global significance as e.g. at the Silurian–Devonian and Frasnian–Famennian boundaries. Some of the others are described for the first time from Central and Southern Europe, and their global nature has to be verified by further investigations. Most δ13C excursions coincide with sea-level changes and the deposition of black shales. A coupling of changes in sea-level, weathering intensity, nutrient supply, organic carbon production, and climate is assumed as driving force of the carbon isotope excursions.

The study of Late Devonian Frasnian and Famennian conodonts in western Thailand confirms these species are mostly cosmopolitan. The Thailand section includes the Upper Kellwasser Event recorded in Europe, North America, China, and elsewhere, and probably also includes the upper part of the Lower Kellwasser Event. Stable isotope geochemistry for this interval shows a positive d13C excursion in the Late rhenana conodont Zone followed by a gradual return to normal, followed by a sudden positive excursion near the conodont extinction event. The latter has been chosen elsewhere as the Frasnian-Famennian boundary. The extinction event seems a consequence of unsteady conditions that could include eutrophic, oxygen, carbon dioxide, eustatic, and temperature fluctuations. There was a regional disappearance or extinction of several conodont species at the Frasnian-Famennian boundary followed by recovery and the spread of new species during the early Famennian.

In this paper, we report the highest and lowest carbon isotope values known from Palaeozoic carbonate rocks. These unusual δ13C values (−50 to +23.5‰) are due to microbial methanogenesis and methanotrophy in Silurian to Carboniferous carbonates. Trace elements were used to decipher the primary mineralogy of the carbonate cements. Very high Sr values and low amounts of Mg, Fe and Mn point toward aragonite precursors, whereas high Fe and Mn values are indicative of primary calcites and allow reconstruction of the redox conditions. Four carbonate deposits are described from the Meseta and the Antiatlas of Morocco, the Pyrenees (France) and the Harz mountains (Germany). The highest δ13C values in concretion below the uppermost Silurian Spinatrypa Mound (Moroccan Meseta) give evidence, that CO2 was produced during methanogenesis. δ13C values between −10 and −32‰indicate that the formation of microbial carbonates and cements in the Middle Devonian Hollard Mound (Antiatlas) and in the Lower Carboniferous sediments of the Iberg (Harz) formed at thermogenetic methane or petroleum seeps. The Late Bashkirian carbonate mound of the High Pyrenees (Tantes Mound) is the first Palaeozoic carbonate with seepage fluids being dominated by biogenic methane. Matrix carbonates exhibit δ13C values as low as −34‰. In some parts, voids make up more than 50 vol% of the mound. They are filled with several generations of cement. The earliest void filling is isopachous fibrous cement, which represents former aragonite. Most negative δ13C values of −50‰were measured in these isopachous fibrous cements. The difference of 55‰in δ13C values between normal sediments and early aragonite cements can only be explained by the contribution of CO2 from anaerobic oxidation of biogenic methane in a cold seep setting.

Lower to Middle Devonian carbonates of the Prague Syncline, the Carnic Alps, the Montagne Noire, and the Cantabrian Mountains were investigated for δ13Ccarb and δ13Corg. These values were measured on bulk rocks, selected components and cements. Many carbonates exhibit primary marine values, but some are altered by diagenesis. A δ13C curve can be presented for the latest Pridolian to Emsian time interval. Several sharp or broad positive excursions are obvious in the woschmidti-postwoschmidti, sulcatus, kitabicus, Late serotinus, and kockelianus conodont zones. The excursion at the Silurian–Devonian boundary is known worldwide and therefore considered global in nature. Some of the others are described for the first time from central and southern Europe, and their global nature has to be verified by further investigations in other regions. Most excursions relate to and/or started during major regressions whereas sea-level highstands correspond to minimal δ13C values. Similar relationships between sea-level changes and δ13C have been observed from other early Palaeozoic intervals. The transgressive Choteč (?) and Kačák events are marked by positive isotope excursions, this type of combination is usually observed in late Palaeozoic to Cenozoic black shale events.