SUMMARY Seismic reflection data across the western margin of the Lake District batholith reveal reflector-poor and reflector-rich areas within components of the intrusion. Synthetic seismograms generated from a series of velocity models have been used to interpret a representative panel of a seismic reflection profile across the western boundary of the batholith. Results indicate that the reflections bounding large, wedge-like reflector-rich zones may be associated with granite/country rock acoustic impedance boundaries. The reflector-rich zones are interpreted as bodies of country rock intruded by the granite and the reflection-poor areas as laccolithic granitic components of the batholith. Reflector-rich areas within the main body of the Lake District batholith may arise from either areas of included country rock, sills or fracture zones within the granite. The areal extent of the wedge-like zones of reflections suggests the intrusion hereabouts comprises a series of laccolithic bodies. It is interpreted that the subsurface western margin of the intrusion has a jagged, ‘cedar-tree’ profile, the intrusive envelope to which is steeper than previous gravity models imply for a ‘simple’ batholith margin. Such a configuration is compatible with observed gravity data.
Mass transfer ami treatability studies were conducted in a stirred Danckwerts cell to investigate the ozonation of 1) simple cyanide, NaCN, and 2) cyanides found in the barren bleed of Giant Yellowknife Mines Limited. A theoretical analysis of the simultaneous absorption and reaction of ozone in a NaCN solution was used to calculate an overall second order rate‐constant for the reaction with ozone. The order of magnitude value at 23°C is 104 to 105 L/(mol.s). Enhancement factors for the ozonation of the barren bleed are in the range of 80 to 300 for bulk total cyanide concentrations of about 38 to 195 mg/L respectively. Attainable treatment levels for cyanide and thiocyanate and stoichiometric relationships are presented along with an economic assessment for an ozone installation for the Giant Yellowknife Mines Limited case.
Seismic reflection data from the Wasdale area, Cumbria, reveal reflector-poor and reflector-rich areas within components of the Lake District batholith. A representative panel of seismic data crossing the western boundary of the intrusion has been modelled with synthetic seismograms. The preferred model indicates that the Ennerdale Granophyre is a sheet-like body some 1100 m thick. Beneath this, the batholith comprises multiple poorly-reflective laccolithic granitic intrusions, interfingered with moderately reflective wedges of country rock, to give the steep western margin of the granite complex a 'cedar-tree' profile. Within the main body of the batholith, reflector-rich zones may arise from either areas of included country rock, basic sills or zones of mafic material within granite.
Basin subsidence and thermal history models of the eastern part of the Midland Valley of Scotland have been constructed to characterise the development of the Midlothian-Leven synclinal basin from the mid Mississippian to the present day. Two modelling programs were used: BasinMod and HotPot. BasinMod models are based on thermal maturity at borehole sites;HotPot models operate on stacks of 2D layer grids using a mechanical compaction method. The thermal and burial history modelling indicates up to 1.9 km of additional burial of Carboniferous strata compared to present day levels: up to 660 m deposited by the end of the Carboniferous period subsequently removed by Variscan uplift and erosion, followed by up to 1.9 km of burial Smith 1995;Rippon et al. 1996). The post-Palaeozoic history is difficult to define due to erosion and overprinting by younger tectonic events. Carboniferous sedimentary basins exhibit faultbounded and synclinal/anticlinal structural styles typical of extensional to strike-slip settings (Read et al. 2002;Rippon et al. 1996;Ritchie et al. 2003;Underhill et al., 2008). One such Carboniferous basin, the Midlothian-Leven syncline (Figure 1), in the eastern Midland Valley of Scotland, has been extensively studied due to a high quality seismic dataset and coastal exposures. Its tectonic and stratigraphical development is well documented (Ritchie et al. 2003;Underhill et al., 2008) and a schematic model has been proposed for the generation of hydrocarbons which occur around its margins (Underhill et al., 2008). However, detailed numerical data on the burial and thermal history of the basin are lacking. This paper integrates maturity data from three boreholes, compaction data from a further eight boreholes ( temperature of burial of Lower to Upper Carboniferous strata and their subsequent postPalaeozoic history. Much of the thermal maturity data is from Raymond (1991).The models are constructed using two contrasting modelling packages; Basinmod and Hotpot.BasinMod (Platte River Associates Inc. software) models compaction and temperature through burial over geological time using stratigraphical and vitrinite reflectance maturity data from a borehole. The first step in HotPot (British Geological Survey (BGS) software) is to undertake a depth of burial study using rock density properties of mudstone to map the predicted thickness of eroded overburden within the study area. A calculation is then applied to restore the depositional thickness (backstripping) of stratigraphical units and construct the basin depositional history model. This is in turn used to compute the thermal history model. HotPot provides a basin-wide overview using grids from structural interpretation, giving a 'broad-brush' basin history.BasinMod provides analysis on 1D boreholes and allows detailed variability in sedimentation rates etc., to be considered. The modelling techniques used by HotPot and BasinMod complement each other and were used iteratively to achieve the final model. Geological settingThe MVS is bounded by the Caledo...
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