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  • 05/2010; 18(2):140 - 147. DOI:10.1111/j.2151-6952.1975.tb00921.x
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    ABSTRACT: Palaeospinax (Lower Jurassic) is the oldest euselachian known from articulated remains, and has certain structural similarities with ctenacanths. Euselachians may therefore have evolved from ctenacanth fishes and not from hybodonts. Nemacanthus Agassiz 1837 (Triassic), known only from finspines, is closely allied to Palaeospinax and may represent an immediate ancestor.
    Zoological Journal of the Linnean Society 06/2008; 60(3):259 - 273. DOI:10.1111/j.1096-3642.1977.tb01029.x
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    ABSTRACT: Detailed sampling of two sections of Turonian-aged Chalk from southeast England for foraminifera has revealed that cyclical abundance changes in many species and genera were mediated by orbitally induced climatic cycles. These cycles can be used for high-resolution stratigraphic correlation of the two sections and as a possible means of re-estimating the duration of the Turonian period.
    Terra Nova 06/2007; 1(5):426 - 431. DOI:10.1111/j.1365-3121.1989.tb00404.x
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    ABSTRACT: There is a correlation between variations in the clay mineral assemblages of the Crackington Formation (Upper Carboniferous) shales in parts of Devon, and the soil series mapped in the same areas. The differences in soil-forming characteristics of the shales are not due to mineralogy alone, but to various states of diagenetic induration which they have achieved. Brown earths (Dunsford series) are formed on steeper slopes of more durable, illite-chlorite dominated shales, whereas clayey soils (Tedburn and Halstow series) are typical of flatter, more poorly drained slopes of weaker illite and illite-kaolinite clay mineral assemblages. This result adds the geological component to earlier views that the different soil series are simply a consequence of physiographic and hydrologic position.
    European Journal of Soil Science 07/2006; 35(4):599 - 606. DOI:10.1111/j.1365-2389.1984.tb00617.x
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    ABSTRACT: Most grabs and corers are inadequate for sampling the sediment-water surface, yet this is a key area for the study of fine-grained sediment and meiofauna. This device was designed specifically to sample the top 1 cm of sediment. The sampling mechanism comprises a scoop which cuts 1 cm deep over an area of 100 cm2 and then seals itself against a closure plate. There is no loss of material through washing during the passage of the sampler to the deck of the ship. It weighs 70 kg, can be used from small boats or research ships, operates in all depths of water, and under wind conditions up to force 9.
    Marine Geology 12/1987; 76:313-317. DOI:10.1016/0025-3227(87)90036-3
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    ABSTRACT: The Carnmenellis granite is one of seven Variscan plutons exposed in SW England which intrude a folded and thrusted succession of metasedimentary and metavolcanic rocks of Devonian and Carboniferous age. The granite contains higher than average radionuclide concentrations which give rise to enhanced heat flow and fracture-controlled, low enthalpy hydrothermal circulation. Measurements of4He in soil gas have been made at 91 sites over the pluton and the surrounding host rocks, in order to assess variation of4He emanation in relation to the distribution of radionuclides and the groundwater circulation system. The pattern of variation obtained shows little correlation with the results of an airborne total gamma-ray activity survey, but agrees well with the distribution of4He in spring waters. Because the occurrence of zones of high4He concentration in these spring waters shows a significant correlation with local variations of heat flow within the pluton, it is believed that the distribution of upwelling limbs of groundwater circulation cells controls the groundwater4He flux. The spatial association of high values of4He in soil gas with high values in spring waters thus suggests that fracture-controlled groundwater circulation systems can be mapped using the soil gas method, even in the absence of springs. However, the variation of4He concentrations in soil gas is more complex than that given by spring waters. This is due to variation in soil moisture content affecting the pore space concentration of4He. Nevertheless, resolution of this effect is possible by statistical analysis of the4He distribution.
    Applied Geochemistry 01/1987; 2(1-2):11-23. DOI:10.1016/0883-2927(87)90056-4
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    ABSTRACT: Techniques established as most successful in the examination of widely variable but mainly oxidised geological materials require separation and isolation of components prior to analysis. These methods reduce the number of variables involved in the production of clastic debris and enable conclusions to be drawn from a practical reversal of rock manufacture. Alkali metals prove successful as indicators of the surficial processes operative during Permo-Triassic times. They demonstrate enrichment by igneous material during early breccia production, and subsequent dilution by wider sedimentation in basins to the east of Cornubia, England.Alkalis in Recent soils, river, estuarine and beach sediments of southwest England are concentrated in the fine-grained (< 2 μm) fraction. Soils developed over Permo-Triassic bedrock, modern river, estuarine sediments, and beach sands, all show anomalous enrichment of trace alkali metals. They reflect the abundance of Li, Rb and Cs in parent material.Geochemical analyses of clays from deep boreholes in the Wessex and Central Somerset Basins enable inter-basin comparisons with the high-alkali deposits of Devon. Absolute trace alkali levels are broadly similar to those of correlated beds at outcrop. Concentrations of Cs prove higher in the Upper Permian than in the Triassic of the Wessex Basin, whilst values show Devonian (Old Red Sandstone) sediments to be un-enriched in Li and Cs. Enrichment of Li over Rb in Triassic Mercia Mudstones of the south Devon coast suggests some Li capture from sabkha brines by clays during evaporite production.
    Chemical Geology 07/1986; 56(1-2-56):143-158. DOI:10.1016/0009-2541(86)90117-8
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    ABSTRACT: To investigate the control on small-scale variation of He in soil gas exercised by minor fracturing, shallow surveys have been carried out over a cave system formed along an approximately orthogonal set of fractures in Devonian limestone in southwest England. The possibilities that He variation could be related to deep-seated, major fractures or hidden mineralisation, and that other soil gases may also be affected by minor fracturing were assessed by contemporary surveys for CO2 and O2. Comparisons of soil gas values with variations in electrical apparent resistivity were also carried out. Location of fractures with direct connection to the cave system was determined by spiking the cave atmosphere with He and then resurveying after equilibration.
    Journal of Geochemical Exploration 09/1985; 24(1):29-49. DOI:10.1016/0375-6742(85)90003-2
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    ABSTRACT: Inland from the north Cornwall coast, from Boscastle to Rusey Cliff, shallow water sandstones (Boscastle Formation and Laneast Quartzite Formation) and slates (Buckator Formation) of Upper Devonian to Namurian age are recognised for the first time. They form the northwestern part of a major nappe which under-thrusts the Upper Carboniferous flysch basin of central Southwest England. Substantial northward displacements are suggested. The problem of conflicting tectonic transport directions in the area is resolved.
    Proceedings of the Geologists Association 01/1985; 96(2):129–141. DOI:10.1016/S0016-7878(85)80063-8
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    ABSTRACT: Constant head injection tests and radioactive tracer experiments at an experimental site in the Carnmenellis granite in Cornwall have revealed a fracture permeability in which water movement is confined to discrete fractures separated by rock of low permeability. Data on flow path frequency, orientation, and effective hydraulic aperture, required for network modelling, have been obtained for a 700-m borehole, with additional hydraulic data from three other boreholes. In addition to fractures of “average” hydraulic conductivity, a small number of major hydraulic features (“main drains”) with major implications for radionuclide migration have been identified. A mean hydraulic conductivity for the granite investigated of 1.57 x 10−7 msec−1 has been obtained, 2.08 x 10−8 msec−1 if the major hydraulic features (with hydraulic conductivities as high as 10−5 msec−1) are excluded.
    Nuclear and Chemical Waste Management 01/1985; 5(4-5):251-267. DOI:10.1016/0191-815X(85)90002-6
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