Mats E. Eriksson

A latest Llandovery to latest Ludlow high-resolution biostratigraphy based on the Silurian of Gotland - a summary

Abstract A succession of 26 conodont zones and 63 successive subzones and conodont faunas have been identified in the exposed latest Landovery to latest Ludlow strata of Gotland, Sweden. All zones, and several of the subzones and faunas, have been identified elsewhere on Baltica, as well as on other palaeocontinents, indicating that this zonation serves well as the standard zonation for calcareous successions. The average duration of the 24 Wenlock and Ludlow zones was 396±208 ka, using the latest radiometric timescale. However, most zones and subzones formed during the widely recognised Silurian oceanic events correspond to less time per unit—in the order of 30 to 100 ka—and most of those formed during intervening episodes correspond to a few 100 ka. The average duration of the 61 Wenlock and Ludlow zones, subzones, and faunas was only 156±82 ka, i.e., among the highest biostratigraphical resolution available for Phanerozoic epochs. On Gotland the combined known maximum thickness of the strata has increased to more than 750 m.

Radionuclide accumulation at a hydroelectric power dam

A Search for Long Lived 242mAm Isotope in Forest Litter Samples from Poland The Fate of Technetium-99 (99Tc) in the North and Nordic Seas after Reduction in the Discharges from Sellafield Further Development of a Fast Method for Determining Plutonium and Amercium in Soils in Germany Accelerator Mass Spectrometry Measurement of 129I in Solid Samples by a Microwave Based Procedure Using Time Resolved Laser Fluorescence Spectroscopy as an Internal Probe for the Phase Changes in Zirconium Oxide Determination of Thorium and Uranium Isotope Ratios in NORM and NORM-polluted Sample Leachates using ICP-QMS Fast Method to Separate AM and PU from Soil Matrix Biosorption of Uranium using Modified Leaf Powder of Platanus Orientalis Development and Validation of the Radiochemical Determination of 99Tc in Environmental Samples Radioactivity in the Irish Sea 129I in Macroalgae (Fucus Vesiculosus) from the Swedish Coast The Effect of Cement Superplasticiser on the Solubility of Radionuclides under Repository Conditions Performance and Characteristics of a Low-Background Germanium Well Detector for Low-Energy Gamma-ray Nuclides Interlaboratory Comparison on the Determination of Radio-Nuclides in Raw Milk in the Year Deep Geological Disposal of Intermediate and Low Level Waste in UK: Experiments to Demonstrate Chemical Containment. Part I Leaching of 239,240Pu and 241Am from Thule Nuclear Bomb Particles Investigated by Sequential Extraction Caesium-137 in Norwegian Coastal Areas Marine Radioactivity in the Channel Islands, 1990 - 2009 Development of a Small Mobile Unit for Emergency Radiological Monitoring of the Foodchain Comparison of Analytical Methods and ICP-MS Correction Schemes Ultra-Trace Determination of Plutonium in Coral Samples using Multi-Collector ICP-MS

Onset of main Phanerozoic marine radiation sparked by emerging Mid Ordovician icehouse

The Great Ordovician Biodiversification Event (GOBE) was the most rapid and sustained increase in marine Phanerozoic biodiversity. What generated this biotic response across Palaeozoic seascapes is a matter of debate; several intrinsic and extrinsic drivers have been suggested. One is Ordovician climate, which in recent years has undergone a paradigm shift from a text-book example of an extended greenhouse to an interval with transient cooling intervals – at least during the Late Ordovician. Here, we show the first unambiguous evidence for a sudden Mid Ordovician icehouse, comparable in magnitude to the Quaternary glaciations. We further demonstrate the initiation of this icehouse to coincide with the onset of the GOBE. This finding is based on both abiotic and biotic proxies obtained from the most comprehensive geochemical and palaeobiological dataset yet collected through this interval. We argue that the icehouse conditions increased latitudinal and bathymetrical temperature and oxygen gradients initiating an Early Palaeozoic Great Ocean Conveyor Belt. This fuelled the GOBE, as upwelling zones created new ecospace for the primary producers. A subsequent rise in δ13C ratios known as the Middle Darriwilian Isotopic Carbon Excursion (MDICE) may reflect a global response to increased bioproductivity encouraged by the onset of the GOBE.

Untangling a Darriwilian (Middle Ordovician) palaeoecological event in Baltoscandia: conodont faunal changes across the ‘Täljsten’ interval

Conodont faunal dynamics and high-resolution biostratigraphy in the lithologically and faunally anomalous ‘Taljsten’ succession, which spans the Darriwilian Lenodus variabilis – Yangtzeplacognathus crassus Zone boundary, were investigated in a 2·5 m-thick section on Mt Kinnekulle that includes an interval yielding fossil meteorites and extraterrestrial chromite. The previous interpretation that this interval reflects a regression is consistent with the occurrence and abundance patterns of some conodont taxa. The disappearance of e.g., Periodon , suggests that the regression began prior to the deposition of the grey ‘Taljsten’. The transition from red to grey limestone coincides with a conspicuous faunal re-arrangement. The lower half of the ‘Taljsten’ reflects a gradual shallowing favourable for some taxa, such as Lenodus , and the immigration of Microzarkodina cf. ozarkodella and Histiodella holodentata . In the middle of the ‘Taljsten’ interval, coinciding with the appearance of abundant cystoids, conditions became less hospitable for conodonts, resulting in a low diversity and low abundance fauna, which occurs to the top of the interval. The overlying red limestone, apparently deposited during a deepening event, marks a return to pre-‘Taljsten’ conditions with a re-organised fauna. The close correlation between the lithologic shifts and conodont faunal changes demonstrates the usefulness of conodonts as environmental indicators.

The middle Cambrian cosmopolitan key species Lejopyge laevigata and its biozone: new data from Sweden

The middle Cambrian Lejopyge laevigata Zone is poorly exposed in Scandinavia. Both this zone, however, and the succeeding Agnostus pisiformis Zone are well exposed at a classic locality at Gudhem, Vastergotland, south-central Sweden. The sequences consist of finely laminated alum shale with scattered stinkstone (orsten) lenses. Three measured and sampled sections yielded a diverse fossil fauna, dominated by trilobites, in particular agnostoids, and the bradoriid Anabarochilina primordialis. Fossils are excellently preserved but restricted to the stinkstones. The L. laevigata Zone at Gudhem includes several geographically widespread key agnostoid species, notably Tomagnostella sulcifera, Clavagnostus spinosus, Glaberagnostus altaicus, Lejopyge laevigata and L. armata. The L. laevigata Zone in Scandinavia is here extended to include the traditional Solenopleura? brachymetopa Zone, and its lower boundary is defined by the FAD of L. laevigata. Trilobite evidence shows that the upper part of the Scandinavian L. laevigata Zone approximately correlates with the Proagnostus bulbus Zone of China and elsewhere. (Less)

Hirnantian (latest Ordovician) delta C-13 chemostratigraphy in southern Sweden and globally: a refined integration with the graptolite and conodont zone successions

The δ13Corg chemostratigraphy of the Hirnantian and lower Rhuddanian in the biostratigraphically well-controlled Röstånga-1 drillcore from west-central Scania is used for an improved integration of the Hirnantian Isotope Carbon Excursion (HICE) with the standard graptolite zonation. In this drillcore succession, the end of the HICE corresponds to the top of the range of Metabolograptus persculptus. Baseline δ13Corg values occur in the uppermost Hirnantian Avitograptus avitus Faunal Interval as well as in the Rhuddanian Akidograptus ascensus Zone, and the isotope curve is also tied to the Swedish uppermost Katian and Hirnantian trilobite zonation. Chemostratigraphic data from sections in Västergötland confirm that the beginning of the HICE is at, or very close to, the base of the Skultorp Member of the Loka Formation. The biostratigraphically less precisely controlled end of the HICE is at least locally in the Upper Member of the same formation. The graptolite biostratigraphy in the Mt. Kinnekulle succession indicates that the lowermost Kallholn Formation, which has long been known as the Leonaspis (formerly Acidaspis) Shale, is of Hirnantian rather than earliest Silurian age which is consistent with the age of the lowermost Kallholn Formation in the Röstånga-1 drillcore. Comparisons with Hirnantian sections in the United Kingdom, North America and China make it possible to improve the calibration of the HICE with conodont and graptolite biostratigraphy and confirm the usefulness of δ13Corg chemostratigraphy for detailed correlations. The upper Katian carbon chemostratigraphy in key sections in North America and eastern Baltoscandia indicates that the Elkhorn and Paroveja excursions are the same. Available data are used for a new Hirnantian eustasy-climate-faunal evolution model.

Plutonium in the marine environment at Thule, NW-Greenland after a nuclear weapons accident

Abstract In January 1968, a B52 plane carrying 4 nuclear weapons crashed on the sea ice 12 km from the Thule Air Base, in northwest Greenland. The benthic marine environment in the 180–230 m deep Bylot Sound was then contaminated with 1.4 TBq 239,240 Pu (0.5 kg). The site was revisited in August 1997, 29 years after the accident. Water and brown algae data indicate that plutonium is not transported from the contaminated sediments into the surface waters in significant quantities. Sediment core data only indicate minor translocation of plutonium from the accident to the area outside Bylot Sound. The present data support an earlier quantification of the sedimentation rate as 2–4 mm per year, i.e. 512 cm during the 29 years since the accident. Biological activity has mixed accident plutonium much deeper down, to 2030 cm, and the 512 cm new sediment has been efficiently mixed into the contaminated layer. In addition to the classical bioturbation mixing the upper _~5 cm, the plutonium data indicate the existence of a deeper bioturbation gradually decreasing with depth. Transfer of plutomum to benthic biota is low leading to 12 orders of magnitude lower concentrations in biota than in sediments. Some biota groups show a somewhat higher uptake of americium than of plutonium. Sediment samples with weapons plutonium from the accident show a significant variation in 240 Pu/ 239 Pu atom ratios in the range 0.0270.057. This supports the hypothesis that the Thule plutonium originates from at least two sources of different quality. The radioecological implication of the observed variations is that the use of plutonium isotope ratios in quantitatively determining the influence of different plutonium sources is a very complex affair requiring substantial data sets.

SILURIAN RAMPHOPRIONID POLYCHAETES FROM GOTLAND, SWEDEN

Abstract Silurian ramphoprionid polychaete annelids, represented by their jaws (scolecodonts), are described from extensive collections from Gotland, Sweden. The family Ramphoprionidae, monotypic at its original description, is sub-divided into four genera; Protarabellites Stauffer, 1933; Ramphoprion Kielan-Jaworowska, 1962; “Pararamphoprion” Männil and Zaslavskaya, 1985; and Megaramphoprion new genus. Identified species include “P.” cf. nordicus Männil and Zaslavskaya, 1985; P. rectangularis new species; P. staufferi new species; P. triangularis new species; and two Protarabellites species left in open nomenclature. Ramphoprion is represented by one new highly plastic species, R. gotlandensis, housing five distinguishable morphotypes showing gradual evolution. Megaramphoprion, which is most closely related to Ramphoprion, is represented by M. magnus new genus and species, a rare but distinctive taxon. Most species have long stratigraphic ranges within which important morphological changes can nonetheless be observed. The stratigraphic range of ramphoprionids includes, at least, the Ordovician to the Silurian. They are fairly rare in the Silurian of Gotland and where present they generally form less than 10 percent of the polychaete faunas, although occasionally reaching as much as 20 to 30 percent. Evolution, paleoecology, and surface structures of the investigated species are briefly discussed.

Furongian (upper Cambrian) biostratigraphy and trilobites of the Haslov-1 drill core, Scania, S. Sweden

Abstract A drilling made in 1972 at Håslöv, Scania, southern Sweden, penetrated a 2572 m thick succession of Phanerozoic strata. The only cored parts of the succession derive from the Upper Ordovician and the Furongian (upper Cambrian) series. Merely the uppermost part of the Furongian was recovered, comprising eight metres of Alum Shale with limestone concretions. Nine species and subspecies of trilobites are identified and their succession is used for subdividing the core into the Peltura scarabaeoides Zone, comprising the Parabolina lobata and the Peltura paradoxa subzones, and the Acerocare Zone, comprising the Peltura transiens Subzone. The conodont Cordylodus proavus? was found in the uppermost part of the core. The faunal succession is interrupted by conspicuous unfossiliferous intervals; the most extensive one measuring 3.39 m. Approximately coeval barren intervals have been recorded from other localities in Scania. Although the ecological significance of these intervals remains to be evaluated, it can be concluded that they are a regional feature in the Furongian of Scania.

Internal soft-tissue anatomy of cambrian 'orsten' arthropods as revealed by synchrotron x-ray tomographic microscopy.

The world-famous ‘Orsten’ Konservat-Lagerstätte has yielded detailed information about Cambrian arthropods and their morphology. Internal organs or soft tissues have, however, rarely been reported, an obvious palaeobiological drawback. In this study, we employed synchrotron radiation X-ray tomographic microscopy (SRXTM) to study microscopic ‘Orsten’ arthropods from the Cambrian of Sweden: Skara minuta and two phosphatocopine species, Hesslandona sp. and Hesslandona trituberculata. This exceptionally high-resolution technique reveals internal organs or soft tissues that allow detailed comparison with equivalent structures in extant crustaceans and functional inferences to be made. The S. minuta specimen shows the digestive system and muscles that extend to the extremities. The slanting anterior portion of the head and anterior position of the mouth with a straight oesophagus suggest a primarily brushing and scraping way of feeding. The prominent head appendage muscles indicate muscle strength and good capacity for food manipulation. In the phosphatocopines the bulbous labrum is one of the most prominent morphological structures of the body. All specimens analysed reveal pairs of muscle bundles within the labrum. Based on comparisons with extant crustacean relatives, these muscles would fulfil the function of moving the labrum up and down in order to open the buccal cavity. The results of this pilot study demonstrate that there is still much to be learned about the ‘Orsten’ taxa.