Oolitic ironstones occur within the Lower Palaeozoic Welsh Basin as isolated deposits found over a wide geographical area. There are two phases of ironstone deposition, a minor Upper Arenig phase and a Mid-Ordovician (Upper Llanvirn to basal Caradoc) phase. Both correlate with eustatic falls of sea level which exposed the Irish Sea Landmass lying immediately to the northwest. This exposure resulted in deep chemical weathering and generation of lateritic soils. Erosion of this material formed the source for the oolitic' ironstones in the Welsh Basin. The ironstones formed above stratigraphic hiatuses on sediment starved shallow water shoals, formed by synsedimentary faulting. These shoals were the favourable sites for the formation of berthierine peloids, which formed the nuclei for ooids. Additionally, they were also the site for the accumulation of berthierine mud, which was closely linked with the development of ferruginous algal mats. Bacterial reduction of organic material associated with ironstones, supplied the necessary reducing conditions for the formation and preservation of berthierine from a kaolinite/iron oxide precursor. Ooids formed by rolling over the muddy surface and mechanically accreting berthierine. Subsequent tidal current reworking of this sediment resulted in the formation of the characteristic lithological features of the ironstones, representing a shallowing-up sequence. Progressive current winnowing led to the formation of a sequence with an upward increasing ooid content and decreasing mud content. The upper facies of the ironstones is an ooid bar deposit worked by tidal currents. Cessation of current reworking allowed faunal colonisation of the bar with significant bioturbation of the sediment, destroying primary sedimentary structures. The presence of some grain-ironstones indicate the original sedimentary state of the upper facies. Tectonic instability during deposition, by synsedimentary faulting, resulted in the formation of disturbed ironstones, and debris flows within the ironstone sequences. Many features of the ironstones are diagenetic in origin, especially the formation of phosphate nodules within the ironstone sequence. These formed just below the sediment/sea water interface, and some nodules were reworked into overlying beds. The source was phosphorus released from adsorption on clays and iron oxides, and also released from organic material. Later siderite development in the ironstones is indicated by the presence of primary cements in grain-ironstones and secondary alterations in pack-ironstones. The generation of diagenetic siderite was dependant upon the amount of organic material within the ironstones, bacterial reduction of which resulted in the formation of bicarbonate and ferrous ions. Sane ironstones were subsequently altered during the Caradoc phase of volcanic activity. The formation of magnetite and stilpnomelane within the ironstones were caused by metasanatic activity associated with dolerite sills and microgranite intrusions. Siderite alteration and base metal sulphides resulted fram late stage hydrothermal activity by some microgranites. Contact metarrorphism by granophyric intrusions led to the extensive replacement of the ironstones by pyrite. Regional metarrorphism resulted in the progressive change of berthierine to chamosite and increased lattice ordering of chamosite.

Carbonate sediments are often highly heterogeneous due to the numerous factors that control deposition. Understanding the processes and controls that are responsible for such complexity has, however, proved problematic. In addition, several of these processes are non-linear, so that depositional stratigraphies may consequently form complicated, perhaps even chaotic, geometries. Forward modelling can help us to understand the interactions between the various processes involved. Here a new three-dimensional forward model of carbonate production and deposition is presented, Carbonate GPM, which is specifically designed to test the interactions between the three main carbonate production controls: light intensity, wave power and carbonate supersaturation, the latter of which is unique to this model. The model also includes transport processes specific to the reef sediment only. The effect of supersaturation and reef transport is demonstrated by comparing the output of three, otherwise, identical runs. From these simulations the need to accurately model the flow of water around a reef system and to correctly take into the account the binding nature of reefal sediments can be seen. Analysis of the stratigraphy generated by changing the antecedent topography by 1m in one locality over a 50km square platform suggest that it may be impossible to predict in detail the stratigraphy of carbonate deposits due to its sensitivity to initial conditions or controlling parameters. This reinforces the conclusions reached using previous process models. However, unlike previous models, our model does not explicitly include nonlinear biological interactions as a control. Instead it shows that similar sensitive behaviour may originate from physicochemical processes alone. External factors, such as sea-level changes, will also influence the complex stratigraphy generated by the model. The effect of several different relative sea-level curves was assessed, each corresponding to a combination of three different hierarchies of sea-level oscillations. Large-scale external processes dominate internal processes, dampening their effect on stratigraphy. However, small-scale, high frequency external processes coupled with autocyclic processes do not show any discernable stratigraphic differences from autocyclcic processes alone. The model also produces an exponential cycle thickness distributions that are similar to those found in ancient deposits.

Fertilizer application and manure use practice in agriculture has become one of the most common sources of dissolved nitrogen species to both ground and surface waters. Nitrogen, released as nitrate (NO3-), ammonium (NH4+) and/or organic nitrogen (DON) is subject to a variety of transformation and attenuation processes in groundwater, including sorption, nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), ammonification and anaerobic ammonium oxidation (anammox). Of these, only denitrification and anammox represent complete attenuation of nitrogen, releasing nitrogen gas (N2). This study examines the occurrence and mechanisms of nitrogen attenuation in groundwater affected by a manure lagoon. Lagoon effluent is in strong contrast to background water with elevated chemical constituents including NH4+ (mean = 121 mg N/L) and DON (218 mg N/L), which are transported through a fast moving groundwater flow system. The NH4+ rich plume interacts with NO3- rich background water at an interface ~3 m below ground surface. Over 100 m of groundwater transport from the source, total nitrogen (TN) was consistently reduced by 90% over two years of study. This reduction can be largely attributed to dilution (~ 80%), but the remaining 10% reflects a component of nitrogen loss due to attenuation, reflecting 32 mg N/L in attenuation and a TN degradation rate of 0.4 mg/L/day. Localized zones of nitrification and denitrification are evidenced by loss of NO3- accompanied by elevated N2O emissions. Anammox is implicated by localized enrichment of δ15N with according decreases in both NO3- and NH4+ at the plume-background interface and through corroborating microbiological study. Ammonification of DON along the flow path, something not observed in similar studies, is conjectured to have a confounding effect on a detailed isotopic investigation by introducing a second source of NH4+ that is depleted in δ15N-NH4+.

Fertilizer application and manure use practice in agriculture has become one of the most common sources of dissolved nitrogen species to both ground and surface waters. Nitrogen, released as nitrate (NO3-), ammonium (NH4+) and/or organic nitrogen (DON) is subject to a variety of transformation and attenuation processes in groundwater, including sorption, nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), ammonification and anaerobic ammonium oxidation (anammox). Of these, only denitrification and anammox represent complete attenuation of nitrogen, releasing nitrogen gas (N2). This study examines the occurrence and mechanisms of nitrogen attenuation in groundwater affected by a manure lagoon. Lagoon effluent is in strong contrast to background water with elevated chemical constituents including NH4+ (mean = 121 mg N/L) and DON (218 mg N/L), which are transported through a fast moving groundwater flow system. The NH4+ rich plume interacts with NO3- rich background water at an interface ~3 m below ground surface. Over 100 m of groundwater transport from the source, total nitrogen (TN) was consistently reduced by 90% over two years of study. This reduction can be largely attributed to dilution (~ 80%), but the remaining 10% reflects a component of nitrogen loss due to attenuation, reflecting 32 mg N/L in attenuation and a TN degradation rate of 0.4 mg/L/day. Localized zones of nitrification and denitrification are evidenced by loss of NO3- accompanied by elevated N2O emissions. Anammox is implicated by localized enrichment of δ15N with according decreases in both NO3- and NH4+ at the plume-background interface and through corroborating microbiological study. Ammonification of DON along the flow path, something not observed in similar studies, is conjectured to have a confounding effect on a detailed isotopic investigation by introducing a second source of NH4+ that is depleted in δ15N-NH4+.

The Howardite-Eucrite-Diogenite (HED) meteorites are a suite of basalts, cumulates and breccias which originate from one differentiated parent body, and are linked to the asteroid Vesta. The HEDs are petrologically diverse with a range of major, minor and trace element compositions. Early crystallisation ages are recorded and so the HEDs provide us with a unique snapshot into the early solar system. The aim of this thesis is to investigate the petrogenesis of the eucrites and diogenites by addressing two questions. What is the Bulk Silicate Vesta (BSV) composition? What differentiation and magmatic processes have occurred? Putative BSV compositions were derived from the geochemistry of the meteorites and geophysical observations of Vesta. Series of one-atmosphere experiments and thermodynamic models investigated the BSV phase relations. Olivine crystallised at ~1625 °C, followed by orthopyroxene at ~1350 °C and feldspar at ~1125 °C. Low-Ca pyroxene-melt partition coefficients for the minor and trace elements were measured. The compatibility of the REEs and HFSEs in low- Ca pyroxene increased by a factor of three, as temperature decreased from 1300-1125 °C and calcium content increased from Wo_0.5-Wo₈. These partition coefficients were combined with the observed phase relations to perform geochemical trace element calculations of differentiation and magmatic processes. My results suggest that BSV had an Mg#(100*(Mg/(Mg+Fe²⁺)) between 75-80, > 43 wt. % SiO₂, 2.5 x CI refractory lithophile elements, 0.5 wt. % MnO and 0.75 wt. % Cr₂O₃. A three stage model for Vesta's evolution is suggested. Firstly, extensive if not global partial melting of BSV. Then, equilibrium crystallisation of the mantle and fractional crystallisation of mantle-derived melts produced diogenitic cumulates and eucrite liquids, accounting for the range in major and trace element abundances. The re-equilibration of trapped melt in cumulates is also thought to have occurred. Finally, crustal anatexis produced the range in trace element fractionations seen.

The purpose of this study was to assess the effect of earthquake instruction on students' earthquake content and preparedness for earthquakes. This study used an innovative direct instruction on earthquake science content and concepts with an inquiry-based group activity on earthquake safety followed by an earthquake simulation and preparedness video to help middle school students understand and prepare for the regional seismic threat. A convenience sample of 384 sixth and seventh grade students at two small middle schools in southern Illinois was used in this study. Qualitative information was gathered using open-ended survey questions, classroom observations, and semi-structured interviews. Quantitative data were collected using a 21 item content questionnaire administered to test students' General Earthquake Knowledge, Local Earthquake Knowledge, and Earthquake Preparedness Knowledge before and after instruction. A pre-test and post-test survey Likert scale with 21 items was used to collect students' perceptions and attitudes. Qualitative data analysis included quantification of student responses to the open-ended questions and thematic analysis of observation notes and interview transcripts. Quantitative datasets were analyzed using descriptive and inferential statistical methods, including t tests to evaluate the differences in means scores between paired groups before and after interventions and one-way analysis of variance (ANOVA) to test for differences between mean scores of the comparison groups. Significant mean differences between groups were further examined using a Dunnett's C post hoc statistical analysis. Integration and interpretation of the qualitative and quantitative results of the study revealed a significant increase in general, local and preparedness earthquake knowledge among middle school students after the interventions. The findings specifically indicated that these students felt most aware and prepared for an earthquake after an intervention that consisted of an inquiry-based group discussion on safety, earthquake content presentation and earthquake simulation video presentation on preparedness. Variations of the intervention, including no intervention, were not as effective in significantly increasing students' conceptual learning of earthquake knowledge.

This study investigated the development potentials in the mineral processing plant of Björkdal. The flotation processes were explored with the purpose of finding out how to achieve a higher and a more uniform gold recovery with adapted choices of parameters. A material balance was carried out to describe in what flows the gold was distributed the current day of sampling. The material was sampled, prepared, and analysed according to gold grade. The sampling method of grab sampling was used and samples from seven occasions during the day were added and created the sample of the day. The sizes of the samples were based on experience but were checked by the Gy´s sampling formula. The sampling was performed during three days and the results were compiled in three material balances, one of which was a fraction balance. The pulp flow, the solid flow and the gold flow were documented as material balances. Deficiencies in the form of imbalances between inflows and outflows were corrected by a method of data reconciliation. The balanced measured values were used for analysis and documentation.In the mine of Björkdal the pH values were measured in the flotation processes. The residence times of the flows through the flotation plant was calculated from the material balance. The additions of reagents were noted and scaled down to the conditions of the laboratory. The conditioning was not included in the Björkdal process.In the flotation experiments at the Mineral processing laboratory, Luleå University of Technology, the influence of the adaptable parameters on the gold recovery was investigated. The following parameters were included in the experiments: pH, flotation time, particle sizes, conditioning time, and reagents additions. The conditions in the Björkdal plant were scaled down to correspond to those of the flotation cells of RÅ0 and RÅ1-3. For the experiments the material was sampled from the RÅ0 entry flow and from the Flotation entry flow. The material samples from the Flotation entry flow replaced the RÅ1-3 entry flow to imitate the conditions of the RÅ1-3 cell. This simplification was motivated by the practical sampling conditions.The results showed that it was possible to achieve a higher gold recovery by adapting pH, residence time and particle sizes. The gold recovery appeared to be independent of conditioning time. The experiment with reagent additions as parameter indicated that higher reagent additions resulted in faster flotation in the introduction part of the process. The report summarized graphically the measurements from the material balance and the flotation experiments in order to give best possible survey of the dependences between parameters and gold recovery. The experiments made it obvious that higher gold recovery resulted in lower gold grade. Therefore a compromise of adjustment between gold recovery and gold grade is important to consider. Variations of the gold recovery could be connected to the geological conditions. In the report significant results were documented. / <p>Validerat; 20130618 (global_studentproject_submitter)</p>

Seafloor properties, including total organic carbon (TOC) and the vertical thickness (isochores) of geological units, are sparsely measured on a global scale and spatial interpolation (prediction) techniques are often used as a proxy for observations. Previous geospatial interpolations of seafloor TOC exhibit gaps where little to no observed data exists. Recent machine learning techniques, based upon a suite of geophysical and geochemical properties (e.g., seafloor biomass, porosity, distance from coast) show promise in making globally complete, comprehensive, and statistically robust geospatial seafloor predictions. Here I apply a non-parametric (i.e., data-driven) machine learning (ML) algorithm, specifically k-nearest neighbors (kNN), to estimate the global distribution of seafloor TOC and marine isochores. This machine learning approach shows major advantages relative to geospatial interpolation, including results that are quantitative, easily updatable, accompanied with uncertainty estimation, and agnostic to spatial gaps in observations. Additionally. analysis of parameter space sample density provides a guide for future sampling. Resulting predictions of the global distribution of seafloor TOC and marine isochore thicknesses were used with ML workflow to predict other seafloor parameters (e.g., heat flow, temperature, salinity) in order to constrain the global distribution of the base of hydrate stability zone and methane generation for all sub-seafloor sediments. Estimating global carbon budgets is first-order dependent on accurate model input, therefore our estimate of the base of hydrate stability zone, and subsequent carbon and methane accumulation in the subseafloor yields improvement over the standard interpolation techniques used in previous global modeling analyses. By using these globally updateable machine learning parameters as the input to predictions, results provide easily updated global budgets of total carbon and methane generated. This dissertation presents valuable new global distributions of seafloor geological properties including total organic carbon, sediment isochores, and subsequently the global distribution of carbon and methane. These estimates should be used in further analysis to understand how carbon is cycled and sequestered in the marine environment. Further, this document is well-suited to serve as a guide for geospatially predicting globally complete seafloor and subseafloor properties.

Results of mineral magnetic, mobile clement, and granulometric analyses of Holocene sediments from Buttermere and Crummock Water (two closely-linked lakes in the north-west of the English Lake District) are presented. These are used to: (1) identify effects of internal (lacustrine) and external (catchment) controls on sedimentation; (2) establish catchment source-lake sediment linkages and assess the value of mineral magnetic techniques in palaeolimnological studies; (3) identify major catchment environmental changes. Analyses of lake sediment fabrics (using sediment thin sections, SEM clay flake analysis, standard granulometric analysis, and mineral magnetic indicators of grain size change) indicate that river plume sedimentation is the normal sediment dispersal mechanism in these lakes. Thin (< = 3.0 mm) chlorite-rich laminae, found at intervals in the otherwise homogeneous Holocene sediment sequence, are probably formed by trapping and concentration of fine, platy particles within lake waters. They are subsequently deposited during lake overturn. This represents an "internal" control on sedimentation. A model of sedimentation processes operating in these lakes is developed, incorporating river plume sedimentation, episodic density surges, and lake thermal structure. Mineral magnetic measurements allow the objective subdivision of the lacustrine lithostratigraphy, identifying broad changes in lake sediment characteristics. Samples from both lake catchments are clustered into six magnetically distinct groups - despite the lithological complexity of the catchment. Comparison of these with the lake sediments has enabled identification of major sources during the Holocene. Following deposition of relatively unaltered bedrock-derived material during the Late-glacial ("primary" sources), secondary sources (which may include glacial diamicts, soils and stream sediments) dominate the lake sediments. Direct input of topsoil-derived sediment from circa 1000 A.D. onwards (during and following the main period of Norse settlement of the Lake District) is identified by its distinctive mineral magnetic characteristics, (high Xfd% values, >-4%). Industrially-derived magnetic spherules contribute significantly to the mineral magnetic characteristics of the more recent sediments, (mainly those post-dating circa 1900 A.D.). These are used to construct a proxy chronology for recent sediments. Catchment environmental changes arc mainly related to stabilisation of vegetation following deglaciation and, from circa 2,000 B.P., anthropogenic effects of deforestation and land disturbance, thus increasing lake sediment accumulation rates. These findings are broadly consistent with the interpretation of the Lake District Post-glacial sediment sequence presented in studies by Mackereth, (1966a), and Pennington, (1981), demonstrating a uniformity of lake and catchment development within the Lake District. A prominent minerogenic layer present in the Buttermere and Crummock Water sediment sequence however broadly correlates with similar horizons deposited in other Lake District lakes from circa 7,400 - 5,000 B.P. These have been previously interpreted as composed of topsoil-derived material derived from human actions, (Pennington 1973, 1981). In the Buttermere and Crummock Water sediments, this layer is best interpreted as derived from glaciogenic sediment') reworked from within the lake basins, probably following lowered lake water levels during the period circa 7,300 - 5,300 B.P. Thus it is suggested that a reinterpretation of similar Lake District lacustrine sediments using the methods employed in this study would be appropriate.

The transport and emplacement mechanisms of the highly energetic pyroclastic density current (PDC) generated in the blast style eruption of Soufriere Hills Volcano, Montserrat, on 26 December 1997 are examined through detailed lithological mapping and sedimentological analysis of the deposits. The PDC formed deposits which range in grain size from coarse breccias to fine ash, with distinctive bipartite layering and well-developed grading and stratification. On a large scale the PDC was highly erosive, sculpting large bedforms and depositing relatively thin deposits. However, locally, centimetre scale topographic protuberances were responsible for significant variations in deposit thickness, grain size, and the development of dune bedforms. The strong lateral and vertical lithofacies variations are attributed to well-developed density stratification, which formed during explosive expansion of the dome prior to PDC formation. Experimental modelling of stratified inertial gravity currents was carried out to investigate the effects of density stratification prior to release of the current. The degree of stratification governs the rate of mixing in the current, which in turn influences the velocity. Well·stratified currents initially move faster than homogenous currents but are slower in the latter stages of current propagation. The results have important implications for deposition from particle-laden flows, which may become stratified with coarser material concentrated at the base of the current. The role of PDCs jn the formation of unit US2-B, emplaced during the Upper Scoriae 2 eruption (79± 8 ka) on Santorini, Greece, was investigated through sedimentological analysis and mapping. Proximally, the unit exhibits features characteristic of emplacement from a flow, such as thickening into palaeochannels and erosive basal contacts. Distally, the unit is of uniform thickness and grain size parameters suggest the deposit is more characteristic of exnplacement from a fallout mechanism. Discrete lenses of fine-grained material within US2-B, and a gradational upper contact with PDC deposits suggest that there may have been contemporaneous deposition resulting the development of a hybrid deposit.