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  • 1
    Online Resource
    Online Resource
    Sequence stratigraphy, chemostratigraphy and facies analysis of Cambrian Series 2 – Series 3 boundary strata in northwestern Scotland
    Cambridge University Press (CUP) ; 2018
    In:  Geological Magazine Vol. 155, No. 4 ( 2018-05), p. 865-877
    Details
    In: Geological Magazine, Cambridge University Press (CUP), Vol. 155, No. 4 ( 2018-05), p. 865-877
    Abstract: Globally, the Series 2 – Series 3 boundary of the Cambrian System coincides with a major carbon isotope excursion, sea-level changes and trilobite extinctions. Here we examine the sedimentology, sequence stratigraphy and carbon isotope record of this interval in the Cambrian strata (Durness Group) of NW Scotland. Carbonate carbon isotope data from the lower part of the Durness Group (Ghrudaidh Formation) show that the shallow-marine, Laurentian margin carbonates record two linked sea-level and carbon isotopic events. Whilst the carbon isotope excursions are not as pronounced as those expressed elsewhere, correlation with global records (Sauk I – Sauk II boundary and Olenellus biostratigraphic constraint) identifies them as representing the local expression of the ROECE and DICE. The upper part of the ROECE is recorded in the basal Ghrudaidh Formation whilst the DICE is seen around 30m above the base of this unit. Both carbon isotope excursions co-occur with surfaces interpreted to record regressive–transgressive events that produced amalgamated sequence boundaries and ravinement/flooding surfaces overlain by conglomerates of reworked intraclasts. The ROECE has been linked with redlichiid and olenellid trilobite extinctions, but in NW Scotland, Olenellus is found after the negative peak of the carbon isotope excursion but before sequence boundary formation.
    Type of Medium: Online Resource
    ISSN: 0016-7568 , 1469-5081
    URL: Article
    DOI: 10.1017/S0016756816000947
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2018
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    detail.hit.zdb_id: 1479206-0
    SSG: 13
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  • 2
    Online Resource
    Online Resource
    Ecosystem Paleobiology and Geobiology: Connecting the Biological and Earth Systems
    Cambridge University Press (CUP) ; 2013
    In:  The Paleontological Society Papers Vol. 19 ( 2013-10), p. xi-xiv
    Details
    In: The Paleontological Society Papers, Cambridge University Press (CUP), Vol. 19 ( 2013-10), p. xi-xiv
    Abstract: Ecology, the study of interactions among organisms and their surroundings, can be approached on multiple scales ranging from the organism to the biosphere (Fig. 1), with unique processes governing interactions and dynamics at each scale. Individual organisms interact with their environment in many ways, including feeding, movement, and respiration. Populations are groups of individuals of a single species living in a local area, and population ecology relates to the dynamics of population size, density, and demographic structure. Communities consist of the populations living and interacting in an area; community ecologists study interactions within communities and their effects on the abundance, diversity, and distribution of species and populations. Ecosystems consist of communities of organisms plus their chemical and physical environment, and ecosystems are typically studied in terms of the movement of energy and nutrients among organisms and the environment. The biosphere encompasses all ecosystems (Fig. 1).
    Type of Medium: Online Resource
    ISSN: 1089-3326 , 2399-7575
    URL: Article
    DOI: 10.1017/S1089332600002655
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2013
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  • 3
    Online Resource
    Online Resource
    Microbial Sedimentology of Stromatolites in Neoproterozoic Cap Carbonates
    Cambridge University Press (CUP) ; 2013
    In:  The Paleontological Society Papers Vol. 19 ( 2013-10), p. 51-76
    Details
    In: The Paleontological Society Papers, Cambridge University Press (CUP), Vol. 19 ( 2013-10), p. 51-76
    Abstract: Stromatolite shapes, sizes, and spacings are products of microbial processes and interactions with topography, sedimentation, and flow. Laboratory experiments and studies of modern microbial mats and sediments can help reconstruct processes that shaped some typical stromatolite forms and some atypical microbially influenced sediments from Neoproterozoic cap carbonates. Studies of modern, cohesive microbial mats indicate that microbialaminite facies in the lower Rasthof Formation (Cryogenian) formed in the presence of very low flow and were not deformed by strong waves or currents. Giant wave ripples, corrugated stromatolites, and tube-hosting stromatolites in basal Ediacaran cap carbonates record interactions between microbes, flow, and evolving bedforms. Preferential cementation in and close to the giant ripple crests is attributed to interactions between flow and local topography. These interactions pumped alkaline porewaters into ripple crests and helped nucleate elongated stromatolites. The similar textures of giant wave ripples and elongated, corrugated, and tube-hosting stromatolites suggest growth in the presence of organic-rich, rounded particles and microbial mats, and in flow regimes that permitted mat growth. These hypotheses can be tested by experiments and models that investigate lithification and the macroscopic morphology of microbial mats as a function of the flow regime, preexisting topography, redox-stratification in sediments, and delivery of organic-rich particles. The widespread microbially influenced textures in Cryogenian microbialaminites and basal Ediacaran cap dolostones record a strong reliance of carbonate deposition on the presence of organic nuclei, supporting carbonate accumulation rates comparable to those in modern reefs. Therefore, the unusual macroscopic morphologies of microbially influenced facies in Neoproterozoic cap carbonates may not reflect oceans that were greatly oversaturated with respect to carbonate minerals.
    Type of Medium: Online Resource
    ISSN: 1089-3326 , 2399-7575
    URL: Article
    DOI: 10.1017/S1089332600002680
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2013
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  • 4
    Online Resource
    Online Resource
    Theoretical Ecospace for Ecosystem Paleobiology: Energy, Nutrients, Biominerals, and Macroevolution
    Cambridge University Press (CUP) ; 2013
    In:  The Paleontological Society Papers Vol. 19 ( 2013-10), p. 1-20
    Details
    In: The Paleontological Society Papers, Cambridge University Press (CUP), Vol. 19 ( 2013-10), p. 1-20
    Abstract: Changes in nutrient cycles and energy fluxes (i.e., ecosystem dynamics) likely drove numerous trends and disruptions in the history of life. Advances in geochemistry offer great insights into paleoecosystem function, as does an understanding of the biogeochemical roles played by ancient organisms. A theoretical ecospace that describes the chemical exchanges between organisms and their environments is presented. Previous descriptions of ecospace principally described spatial and physical aspects of ecology; the new ecospace description broadens the concept to encompass a wider range of ecological processes that control abundance and diversity of fossil organisms. Organisms require materials from the environment for generating energy and building tissues, and these factors are broken down, ultimately specifying particular substances acquired from the environment. Different organisms require specific substances in different amounts depending on factors such as physiology, environmental conditions, etc.; thus, physiological ecospace describes an organism's sensitivity to ecosystem/earth system perturbations and trends. Several examples relating to organisms' requirements for skeletal minerals are reviewed, and a new analysis of extinction selectivity related to ocean acidification is presented. Selective extinction of heavily calcified metazoa is demonstrated to have occurred at least eight times during the Phanerozoic, including the early Cambrian, Frasnian (Late Devonian), and Aptian (Early Cretaceous). Multidimensional structure of ecospace occupation (e.g., correlations among ecological traits) strongly controls the effects of an extinction such that the same kill mechanism applied at different times will affect the ecological composition of the biosphere in a variety of ways.
    Type of Medium: Online Resource
    ISSN: 1089-3326 , 2399-7575
    URL: Article
    DOI: 10.1017/S1089332600002667
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2013
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  • 5
    Online Resource
    Online Resource
    Trace Fossils with Spreiten from the Late Ediacaran Nama Group, Namibia: Complex Feeding Patterns Five Million Years Before the Precambrian–Cambrian Boundary
    Cambridge University Press (CUP) ; 2014
    In:  Journal of Paleontology Vol. 88, No. 2 ( 2014-03), p. 299-308
    Details
    In: Journal of Paleontology, Cambridge University Press (CUP), Vol. 88, No. 2 ( 2014-03), p. 299-308
    Abstract: Here we describe large, complex trace fossils in the late Ediacaran Omkyk Member of the Zaris Formation, Nama Group, southern Namibia. The horizontal trace fossils are preserved on a number of talus blocks from a bedding plane of a cm-thick sandstone lens from a single stratigraphic horizon less than 100 m below an ash bed dated at 547.3 ± 0.7 Ma. The forms consist of overlapping U-shaped spreiten elements with parallel limbs surrounded by an outer tube. Individual U-shaped elements are 0.2 to 1 cm in diameter, the outer tube is less than 3 mm in diameter, and the forms as a whole range from 5 to 30 cm long and 3 to 10 cm wide. The specimens commonly show a change in direction and change in diameter. The morphology of these trace fossils is comparable to backfill structures, particularly specimens of Paleozoic Zoophycos from shallow water environments. Here we interpret these horizontal spreiten-burrows to record the grazing of the trace-maker on or below a textured organic surface. The identification of large late Ediacaran trace fossils is consistent with recent reports of backfilled horizontal burrows below the Precambrian–Cambrian boundary and is suggestive of the appearance of complex feeding habits prior to the Cambrian trace fossil explosion.
    Type of Medium: Online Resource
    ISSN: 0022-3360 , 1937-2337
    URL: Article
    DOI: 10.1666/13-042
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2014
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    detail.hit.zdb_id: 2047591-3
    SSG: 13
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