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Ayress M.A.,Ichron Ltd | Whatley R.C.,Aberystwyth University
Palaeontology | Year: 2014

Twenty-seven species of well-preserved and abundant Early Cretaceous non-marine ostracod crustaceans were recovered from the North Falkland Basin. The assemblage is unusually diverse for a non-marine palaeoenvironment and is sourced from cuttings samples collected during 2011 drilling of wells by Desire and Rockhopper Exploration, in the northern and southern areas of the basin. Ostracoda are entirely undocumented in published accounts from this basin, and all but one species appear to be new to science. For the new taxa, one new family (Alloiocyprideidae; type genus Hourcqia) is proposed and includes Hourcqia woodi sp. nov. Four new genera are erected: Falklandicypris gen. nov.; type species F. petrasaltata sp. nov., Gangamoncythere gen. nov.; type species G. colini sp. nov., Paraplesiocypridea gen. nov.; type species P. alloios sp. nov., and Musacchiocythere gen nov.; type species M. sarunata (Musacchio, ). Nine other species are described as new and are Falklandicypris desiderata, Clinocypris epacrus, Cypria poietes, Ilhasina? leiodermatus, Looneyellopsis tuberculatus, Theriosynoecum petasmathylacus, Theriosynoecum ballentae, Timiriasevia fluitans, and Vecticypris samesi. The remainder are left in open nomenclature due to paucity of material. The ostracod assemblage is largely restricted to the southern part of the basin (wells 25/5-1 and 26/6-1). In the northern part of the basin only four species, dominated by Vecticypris samesi, are present and with one possible exception are restricted there. There appears to have been little or no interchange of species suggesting that a barrier probably existed between the northern and southern regions. The more diverse southern assemblage indicates that more favourable conditions existed to the south. Stratigraphically, a distinct change in faunal composition recorded in both southern wells is likely to be an isochronous event correlatable across the southern area, and of an age no younger than Hauterivian. © The Palaeontological Association. Source

Lee D.E.,University of Otago | Lindqvist J.K.,University of Otago | Beu A.G.,Institute of Geological & Nuclear Sciences | Robinson J.H.,University of Otago | And 3 more authors.
New Zealand Journal of Geology and Geophysics | Year: 2014

A new fossil locality of Late Oligocene (Duntroonian) age at Cosy Dell farm, Waimumu, southern New Zealand has yielded a diverse array of exceptionally well-preserved fossils derived from rocky shore, sandy beach and estuarine habitats. A lag deposit of Jurassic Murihiku basement boulders and cobbles is overlain by richly fossiliferous, locally concretionary, pebbly shellbeds. The fauna is remarkable for its taxonomic diversity. It includes thick-shelled bivalves and large gastropods, an abundance of juveniles and micromolluscs, and species with nacreous shell and colour patterns preserved. More than 350 species of molluscs are present, including 10 chitons, 90 bivalves and 250 gastropods. Other notable components of the biota include > 125 ostracod species, barnacles, foraminifera, brachiopods, bryozoans, echinoderms, hermatypic corals, otoliths and penguin bones. Oyster-encrusted and pholad-bored boulders, and intertidal and estuarine species indicate proximity to a rocky coastline and estuary, confirming the presence of land in southern New Zealand during Late Oligocene times. © 2014 © 2014 The Royal Society of New Zealand. Source

Molyneux S.G.,British Geological Survey | Delabroye A.,French National Center for Scientific Research | Delabroye A.,Ichron Ltd | Wicander R.,Central Michigan University | Servais T.,French National Center for Scientific Research
Geological Society Memoir | Year: 2013

Early to mid Palaeozoic marine phytoplankton are represented by acritarchs and associated forms, which had a global distribution from the early Cambrian to the early Carboniferous (Mississippian). Palaeozoic phytoplankton assemblages show varying degrees of cosmopolitanism and endemism through time. A high degree of cosmopolitanism was evidently characteristic of the Cambrian and much of the Late Ordovician, Silurian and Devonian, but provincialism was more marked in the Early Ordovician and Hirnantian (latest Ordovician), the latter at a time of major palaeoenvironmental perturbations. Distribution patterns of Palaeozoic phytoplankton are attributed to a number of interacting factors, including palaeolatitude, palaeotemperature, oceanic circulation patterns, the disposition of continents, differentiation between oceanic and cratonic (distal-proximal) assemblages, and sedimentary environments and facies. There are indications that biogeographical ranges of taxa shift over time. Moving our understanding of Palaeozoic phytoplankton biogeography forward requires (1) targeted investigation of regions and time periods for which no or little data exist, (2) quantitative analysis of data to investigate how similarity between regions varies through time and how this might correlate with other datasets such as carbon isotope stratigraphy or sea-level, and (3) rigorous application of well-defined time slices to compare coeval assemblages, at least within the limits of resolution © The Authors 2013. Source

Khanna N.,University of St. Andrews | Khanna N.,Ichron Ltd | Godbold J.A.,University of Southampton | Austin W.E.N.,University of St. Andrews | And 2 more authors.
PLoS ONE | Year: 2013

Culturing experiments were performed on sediment samples from the Ythan Estuary, N. E. Scotland, to assess the impacts of ocean acidification on test surface ornamentation in the benthic foraminifer Haynesina germanica. Specimens were cultured for 36 weeks at either 380, 750 or 1000 ppm atmospheric CO 2. Analysis of the test surface using SEM imaging reveals sensitivity of functionally important ornamentation associated with feeding to changing seawater CO2 levels. Specimens incubated at high CO2 levels displayed evidence of shell dissolution, a significant reduction and deformation of ornamentation. It is clear that these calcifying organisms are likely to be vulnerable to ocean acidification. A reduction in functionally important ornamentation could lead to a reduction in feeding efficiency with consequent impacts on this organism's survival and fitness. © 2013 Khanna et al. Source

In a sedimentological sense a fluvial to tidal transition zone can be defined in rivers as a zone that separates the upstream fluvial from the downstream estuarine zone. Characteristic sedimentary structures within this zone are notoriously difficult to recognize. This study demonstrates the influence of tidal modulation within the most proximal part of the fluvial-tidal transition zone (i.e. the 'backwater zone') of an ancient fluvial system. Criteria have been established to differentiate between purely fluvial facies and those modulated by tidal energy. The stratigraphic interval from which the data were derived is the Lourinhã Formation (Late Jurassic) of the Lusitanian Basin, Western Portugal. An analysis of sedimentary features at four key localities has identified a temporal spectrum of tidal influence ranging from the daily modulation of fluvial flows to the effects of tidal bore passage. A combination of quantitative and qualitative data reveals systematic changes in the internal architecture of dune-scale bedforms deposited in a channel-floor setting. The key co-occurring features are: (i) increasing-decreasing organic particle concentration; (ii) increasing-decreasing bottomset thickness; (iii) increasing-decreasing foreset dip and shape (from convex to concave); and (iv) increasing-decreasing brinkpoint height. Collectively, these features are interpreted as having been produced by successive fluctuations in flow regime conditions from lower (during flood tidal retardation) to higher (during ebb tidal drawdown) current velocities. Bedforms showing these features occur in both meandering fluvial channels and straighter distributary systems. In addition, several examples of a specific type of stepped erosion surface and draping sediment have been recognized, the interpretation of which strongly suggests generation by the passage of tidal bores. If this interpretation is correct, then it represents one of the first published examples of tidal bore propagation in ancient fluvial systems. Palaeoclimatic evidence (cellular analysis of woody tissue, palaeosol character and plate reconstruction) indicates a warm, seasonal, winter wet to summer dry climate during deposition of the Lourinhã Formation. From this evidence it is suggested that tidal modulation and tidal bore effects are more likely to develop in the 'dry season', when fluvial flow in the main river channels was reduced. © 2010 The Authors. Journal compilation © 2010 International Association of Sedimentologists. Source

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