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No description available.

The Lower Tertiary volcanic sequence of the Blosseville Coast region was erupted in a 3 m.y. period immediately prior to the initiation of sea floor spreading in the adjacent part of the North Atlantic. This volcanic province is comprised of a major flood basalt sequence (the Plateau Lavas), the eruption of which was preceded by localised basaltic volcanism (the Lower Lavas) and succeeded by eruptive activity which produced minor volcanic cones.The Lower Lavas and Plateau Lavas comprise the Blosseville Group and these volcanics are entirely tholeiitic in character. The evolution of these lavas can be described in terms of their derivation from mantle sources of limited isotopic and chemical variability. Bulk contamination of these magmas has generated additional isotopic variability though indicating minimal contamination in the majority of cases. The major and trace element compositional diversity amongst these magmas was controlled by a fractionation process involving olivine, clinopyroxene and plagioclase.Two magmatic types are present amongst the Nunatak Group lavas. These volcanics are predominantly alkaline in character and comprise a series of petrographic types which were generatedby low pressure fractionation of picritic parents. These alkaline types were derived from mantle sources with considerable trace element and isotopic variability. The tholeiitic magmas of the Nunatak Group are intimately related to those of the Blosseville Group.It is suggested that the tholeiitic magmas of the region represent the initial establishment of the Icelandic hotspot in the early Tertiary. This magmatic activity has tapped similarmantle sources throughout its history. The alkaline magmas were dervied from fundamentally different mantle sources and are probably generated through tectonic/thermal disturbance of the sub-continental mantle.

The Pennine Basin has undergone a complex geological history with major episodes of rifting, thermal subsidence and inversion, the pattern of which was largely controlled by the structure of the Caledonian basement. The resulting block and basin topography and differential subsidence led to major variations in sediment thickness throughout the basin. In the Dinantian, carbonate sediments were dominant changing to clastic dominated sediments in the Namurian and Westphalian. Thick accumulations of peat led to the formation of numerous coals, mainly in the Westphalian. There were periodic marine incursions, many of them correlatable over the whole of NW Europe. The boreholes were selected to give an approximate E-W traverse across the deepest part of the basin, with additional field and deep mine sample coverage. The samples encompass an age range from the base of the Permian down to topmost Dinantian. Vitrinite reflectance is the most consistently reliable indicator of maturity, giving the best trends with increasing depth for all the boreholes, bar Carlow 2, Knutsford 1 and Hayfield Farm. The aromatic maturity parameters proved to be the most useful of the geochemical parameters and of these MPI1 and % Rc were the most reliable, giving good depth related trends for all the boreholes bar Knutsford 1, Calow 2 and Hayfield Farm. A problem with MPI1 and % Rc is that the alkylphenanthrene parameters reverse at higher maturities, thought to be due to a change in the reactions involved. Consequent to this there is a change in the equations used to calculate % Rc which, for this study, applies only to the samples below the lower fault in Up Holland 1 and to the sill sample from Gainsborough 2. The aliphatics parameters are at or near their end point for most of the samples. For Gainsborough 2, the C_{29αalphaα 20S/20S}+ 20R ratio attains equilibrium at around 1000m depth and thus can be used as a further constraint on the thermal history in the basin modelling.

<p> This dissertation examines the influence which a geophysical process (giant impacts) has on a geochemical marker (composition) during terrestrial planet formation. Simultaneously studying all planets maximizes the available constraints and permits examination of controls on the overall composition of the Earth. I also examine the Galilean satellite system to determine the universality of the terrestrial conclusions. </p><p> The late stages of planetary accretion involve stochastic, large collisions. Impact-related erosion and fragmentation can have profound consequences for the rate and style of accretion and the bulk chemistries of terrestrial planets. However, the previous predominate assumption in computer models of accretion was that all collisions resulted in perfect merging despite the likelihood of these collisions producing a range of outcomes (e.g., hit-and-run, removal of material from target, or production of several post-collision bodies). In this work, I investigate the effects of late-stage accretion with multiple collision types and the consequences on the bulk (mantle/core) and isotopic (Hf&ndash;W) composition. </p><p> My model is composed of two parts: (1) N-body accretion code tracks orbital and collisional evolution of the bodies and (2) geochemical post-processing evolves composition in light of impact-related mixing, partial equilibration and radioactive decay. For terrestrial planets, Part (1) is Chambers (2013, Icarus) and incorporates multiple collisional outcomes. For Galilean satellites, Part (1) is Ogihara &amp; Ida (2012, Icarus) and assumes perfect merging for all collisions thus the model is not self-consistent (it likely overestimates compositional changes). </p><p> For the terrestrial planets, the results are consistent with observed mantle/core ratios and tungsten isotopic anomalies. A moderate (approx. 0.4) core equilibration factor is preferred due to protracted accretion time. It is important to include multi-modal collisions when modeling planet formation if composition, timescales, or spatial distribution of mass are being investigated. </p><p> I could not reproduce the observed ice fraction gradient of the Galilean satellites, even with an initial compositional gradient and vaporization of water ice. Some other physical process(es) are needed, perhaps tidally-driven volatile loss at Io and Europa. Extensive inward radial migration smooths out initial compositional gradients.</p>

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<p> Quantification of groundwater-surface water exchange and the role of hyporheic flow in this exchange is increasingly of interest to a wide range of disciplines (e.g., hydrogeology, geochemistry, biology, ecology). The most direct method to quantify groundwater-surface water exchange is a seepage meter, first developed in the 1940s. Widespread use of the traditional 1970s-era 55-gallon half-barrel seepage meter has shown that the method is subject to potential errors, particularly in flowing waters (e.g., streams, rivers, tidal zones). This study presents two new direct seepage measurement devices, the Shelby tube and the seepage blanket, designed to minimize potential measurement errors associated with flowing surface waters. The objective of the study is to develop and test the new methods by comparing results (specific discharge, hydraulic conductivity, and dissolved constituent concentration) to established methods. Results from both laboratory and field testing suggest that the new devices have utility in quantifying the water and dissolved constituent exchange between surface water and groundwater.</p>