<p> Gabbroic dyke and syenitic plug intrusives have been sampled and studied across Huerfano Butte. Petrography and geochemical analyses were performed on selected specimens; from these analyses chemical variation diagrams have been prepared. Crystal Size Distribution analyses have been done on magnetites and olivines to determine crystal nucleation and growth rate in the dyke. These data have been used to infer aspects of the evolution of Huerfano Butte.</p> / Thesis / Bachelor of Science (BSc)

Thesis (MSc(Geography and Environmental Studies))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: In an area where mining activities dominate, there are likely to problems that need effective environmental management approaches, which can be facilitated through legislation and environmental management systems (EMS). The Great Dyke in Zimbabwe is a strategic economic resource with significant quantities of chrome and platinum. Chrome mining occurs across the whole length of the Great Dyke with most of the operations under Zimasco claims. Zimasco mining operations fall into two categories: the organization‟s own claims operated in its own right and claims that are leased out to a second party forming a tribute system from which tributor miners produce chromite ore exclusively for Zimasco. This study examines the environmental management approaches used by Zimasco operations, in particular the National Occupational Safety Association (NOSA) Integrated Five Start System, in order to identify the usefulness of EMS in the mining industry. Firstly, the current environmental impacts associated with the mining activities were identified and problem areas highlighted, after which environmental management approaches linked to national legislation were examined in terms of their contribution towards sound environmental management. A legal compliance checklist was carried out on the existing mines to assess levels of compliance to standards stipulated in the Environmental Management Act Chapter 20:27. This was followed by questionnaire surveys used for impact identification and the data was analysed using the aspect and impact analysis matrix. Underground mines with effluent discharges were assessed by means of an effluent analysis as a way of determining the effectiveness of the approaches on the mines. Recommendations for changes were made following a Strength Weaknesses Opportunities and Threats (SWOT) analysis of the approaches and system. Major environmental problems highlighted included unattended waste rock dump and pits as well as dissolved substances in effluent discharge. Although evidence of compliance to environmental legislation for the mining operations was found at administrative level, this was often not executed in operation. Limited hazards were observed in effluent discharge from mines under full implementation of the EMS. It is recommended that all mining operations need to be covered by an EMS system for improved environmental management and sustainable development. Effective implementation of legislation and EMS on the ground provides a better platform for sound environmental management. / AFRIKAANSE OPSOMMING: In 'n area waar grootskaalse mynbou aktiwiteite die omgewing kan affekteer word effektiewe omgewingsbestuur benodig. Die Groot Dyk in Zimbabwe is 'n strategiese ekonomiese hulpbron met groot hoeveelhede chroom en platinum. Chroom word grotendeels onder Zimasco kleims langs die Groot Dyk ontgin. Zimasco mynbedrywighede val in twee kategorieë: eerstens eie kleims wat direk deur Zimasco bedryf word, en tweedens kleims wat aan 'n tweede party verhuur en bewerk word en chroom eksklusief aan Zimasco lewer. Die omgewingsbestuursbenadering wat deur die Zimasco mynbedrywighede gebruik word, veral die NOSA Geïntegreerde Vyfster Stelsel, is bestudeer om vas te stel of omgewingsbestuurstelsels (OBS) effektief kan wees in die mynbedryf. Eerstens is die huidige omgewingsimpte veroorsaak deur mynbedrywighede geïdentifiseer en probleemareas uitgelig. Verder is die omgewingsbestuursbenadering in die lig van nasionale wetgewing bestudeer om die bydrae tot gesonde omgewingsbestuur toe te lig. 'n Lys is opgestel waarin die mate waartoe geselekteerde myne aan bestaande wetgewing voldoen bepaal is. Vraelyste is ook gebruik om die omgewingsimpak te identifiseer en data is met behulp van die aspek en impak analise matriks geanaliseer. 'n Afvoeranalise is op ondergrondse myne gedoen ten einde die effektiwiteit van omgewingsbestuursbenadering op die myn te bepaal, terwyl 'n SWOT analise van beide die benadering en die NOSA Vyfster Stelsel uitgevoer is met die oog op aanbevelings. Die belangrikste omgewingsimpakte langs die Groot Dyk sluit in: afvalrotshope, kuipe en slote vanaf oppervlakbedrywighede asook opgeloste afval in afloop vanaf ondergrondse myne. Bewyse van voldoening aan omgewingswetgewing is wel gevind in myndokumentasie, maar nie altyd in die praktyk nie. Laer vlakke van toksiese uitvloeisel vanaf myne waar OBS geïmplementeer is, is bewys van die suksesvolle gebruik van „n geïntegreerde OBS. Alle mynaktiwiteite moet ingesluit word in „n OBS stelsel om beter omgewingsbestuur en volhoubare ontwikkeling te verseker. Effektiewe implementering van wetgewing en OBS op die laagste vlak in mynaktiwiteite bied 'n beter platform vir gesonde omgewingsbestuur in die mynbedryf.

There are many examples worldwide were fossil magmatic intrusions influence the local water and energy supply. Due to that intrusions can act as a conductor and a reservoir, but also as a barrier for fluids and gases in the ground. The decisive feature between conductor or barrier in an intrusion is its fracture network. Hence it is of paramount importance to characterize an intrusion’s fracture network and thus its permeability. However, other than through boreholes magmatic intrusions are rather inaccessible and very little is known about their influence on aquifers and reservoir rocks in the underground. It is therefore important to increase the knowledge of magmatic intrusion by investigate the intrusions that are accessible for us at ground surface. In this study, photos from a case study about the Sosa dyke have been used to map and characterizes the fractures of the Sosa dyke, which is an accessible vertical magmatic intrusion and a part of the Chachahuén volcano complex in the southwestern parts of Argentina. The photos that were used are taken with an UAV (unmanned aerial vehicle), and to analyze the photos, map the fractures and produce the results, software as Agisoft Metashape, MOVE™ and MATLAB with the toolbox FracPaQ was used. The intrusion has two distinct fracture sets, one that is perpendicular to the intrusion margins and one that stretches parallel with the intrusion. The connectivity of the fractures is low, and since the permeability of the fractures largely depends on the connectivity, it is also low. The fracture set that is perpendicular to the intrusion margin is what’s called cooling fractures, which is created as the magma in the intrusion cools. This causes the magma to contract and break, forming fractures perpendicular to the inward migrating solidification front. The fracture set that is parallel with the intrusion is caused by minerals in the magma flow being affected by friction from the intrusion margins. This causes the minerals in the magma to elongate in the direction of flow along the sides of the dyke, creating foliation, enabling fractures to propagate along. These fracture sets are poorly connected which concludes that the mapped area of the Sosa-dyke has a low permeability. / I hela världen finns det många exempel där stelnade magmatiska intrusioner påverka ett områdes vatten och energiförsörjning, på grund av att intrusioner kan agera som ledare och reservoarer men också som barriärer för vätskor och gaser in marken. Den avgörande faktorn mellan ledare och barriärer i en intrusion är dess spricknätverk. Därför är det viktigt att kartlägga och karakterisera en intrusions spricknätverk och därmed också få en uppfattning om dess permeabilitet. Magmatiska intrusioner är förutom genom borrhål ofta svåråtkomliga, det finns därför väldigt lite information om hur de påverkar akviferer och reservoarer i marken. Det är därför viktigt att öka kunskapen om magmatiska intrusioner genom att undersöka intrusionerna som är tillgängliga vid markytan. I denna studie har bilder från en fallstudie om Sosa Intrusionen använts för att kartera och karakterisera sprickor i Sosa intrusionen. Det är en vertikal magmatisk intrusion som är synlig på markytan, och en del av Chachahuén vulkan komplexet i sydvästra Argentina. Bilderna som användes är tagna med en UAV( unmanned aerial vehicle), och för att analysera bilderna, kartera sprickorna och producera resultaten, användes programmen Agisoft Metashape, MOVE™ och MATLAB med FracPaQ verktyget. Intrusionen har två distinkta sprickgrupper, en som är vinkelrät mot intrusionens kanter och en som går parallellt med kanterna. Konnektivitet mellan sprickorna är låg och eftersom permeabiliteten påverkas av konnektiviteten är den också låg. Sprickgruppen som är vinkelrätt mot intrusionskanten är så kallade kylningssprickor och bildas nät magman i intrusionen svalnar. Det leder till att magman kontraherar och spricker, och bildar sprickor som går inåt mot stelningsgränsen och därmed vinkelrätt mot intrusionskanten. Sprickgruppen som går parallellt med intrusionen bildas av att mineral i magmaströmmen påverkas av friktion från intrusionskanterna. Det gör att mineralen lägger sig och sträcks ut i samma riktning som magmaflödet, vilket när magman stelnar bildar svaghetszoner som sprickor kan fortplanta sig i. Dessa sprickgrupper har låg konnektivitet vilket gör att slutsatsen blir att det karterade området av Sosa intrusionen har låg permeabilitet.

Although soils developed from ultramafic parent materials have significance to agriculture, ecology and health, their bio-geochemistry is poorly understood. The mineralogical and bio-geochemistry of soils formed from the ultramafic parent materials of the Great Dyke, Zimbabwe and Gillespie County, Texas was investigated. The objectives were to determine the mineralogical and bio-geochemical properties of the soils in order to assess the potential impact and challenges to agriculture, and environmental quality. Soil samples were taken from the crest, shoulder, footslope and the toeslope. Chemical analyses were performed by nuclear and spectroscopic techniques. Mineral characterization was conducted by x-ray diffraction (XRD) and spectroscopic techniques. Microbial whole-community structure was determined by the fatty acid methyl esters (FAME) technique. The results indicate wide chemical and mineralogical compositions among the studied sites. The soils contain relatively high concentrations of heavy metals (some sites contain Cr(VI)), but low levels of K and Ca. The highest concentrations of trace metal were associated with chromite, Fe oxides and serpentinite. The concentrations of Mg were higher than those of Ca and varied between Zimbabwe and Texas soils largely due to the parent materials. Unique to these soils is the occurrence of talc, serpentine, chlorite, Fe-rich smectite, amphiboles, pyroxenes, Fe and Cr oxides in relatively large amounts. These soils also lack micas and have neglible amounts of kaolinite and feldspars. Palygorskite and serpentine occurred in specific soil horizons and at specific landscape positions. FAME profiles indicate that the soil microbial community structure is predominantly bacteria and fungi (including arbuscular mycorrhiza fungi) at each landscape position across the transect. Biomarkers for actinomycetes were undetectable. The proportions of Gram-positive bacteria were higher than those of the Gram-negative bacteria. Very low levels of nutrients (Ca and K), higher Mg/Ca molar ratios, and the relatively high concentrations of heavy metals in these soils impact agricultural productivity. High concentrations of heavy metals, the presence of the Cr(VI) as well as its great potential to form in these soils might impact microbial activity and environmental quality. The occurrence of fibrous minerals (e.g serpentine and amphiboles) in these soils will likely impact human health.

The evolution of rhyolitic lava from effusion to cessation of activity is poorly understood. Recent lava dome eruptions at Unzen, Colima, Chaiten and Soufrière Hills have vastly increased our knowledge on the changes in behaviour of active domes. However, in ancient domes, little knowledge of the evolution of individual extrusion events exists. Instead, internal structures and facies variations can be used to assess the mechanisms of eruption. Rhyolitic magma rising in a conduit vesiculates and undergoes shear, such that lava erupting at the surface will be a mix of glass and sheared vesicles that form a permeable network, and with or without phenocryst or microlites. This foam will undergo compression from overburden in the shallow conduit and lava dome, forcing the vesicles to close and affecting the permeable network. High temperature, uniaxial compression experiments on crystal-rich and crystal-poor lavas have quantified the evolution of porosity and permeability in such environments. The deformation mechanisms involved in uniaxial deformation are viscous deformation and cracking. Crack production is controlled by strain rate and crystallinity, as strain is localised in crystals in crystal rich lavas. In crystal poor lavas, high strain rates result in long cracks that drastically increase permeability at low strain. Numerous and small cracks in crystal rich lavas allow the permeable network to remain open (although at a lower permeability than undeformed samples) while the porosity decreases. Flow bands result from shear movement within the conduit. Upon extrusion, these bands will become modified from movement of lava, and can therefore be used to reconstruct styles of eruption. Both Ngongotaha and Ruawahia domes, from Rotorua caldera and Okataina caldera complex (OCC) respectively, show complex flow banding that can be traced to elongated or aligned vents. The northernmost lobe at Ngongotaha exhibits a fan-like distribution of flow bands that are interpreted as resulting from an initial lava flow from a N – S trending fissure. This flow then transitioned into intrusion of obsidian sheets directly above the conduit, bound by wide breccia zones which show vertical movement of the sheets. Progressive intrusions then forced the sheets laterally, forming a sequence of sheets and breccia zones. At Ruawahia, the flow bands show two types of eruption; long flow lobes with ramp structures, and smaller spiny lobes which show vertical movement and possible spine extrusion. The difference is likely due to palaeotopography, as a large pyroclastic cone would have confined the small domes, while the flow lobes were unconfined and able to flow down slope. The vents at Ruawahia are aligned in a NE – SW orientation. Both domes are suggested to have formed from the intrusion of a dyke. The orientations of the alignment or elongation of vents at Ngongotaha and Ruawahia can be attributed to the overall regional structure of the Taupo Volcanic Zone (TVZ). At Ngongotaha, the N – S trending elongated vent is suggested to be controlled by a N – S trending caldera collapse structure at Rotorua caldera. The rest of the lobes at Ngongotaha, as well as other domes at Rotorua caldera, are controlled by the NE – SW trending extensional regional structure or a NW – SE trending basement structure. The collapse of Rotorua caldera, and geometry of the deformation margin, are related to the interplay of these structures. At Ruawahia, the NE – SW trending vent zone is parallel to the regional extension across the OCC, as shown by the orientation of intrusion of the 1886AD dyke through the Tarawera dome complex. The NE – SW trending regional structures observed at both Rotorua caldera and Okataina caldera complex are very similar to each other, but differ from extension within the Taupo rift to the south. Lava domes, such as Ngongotaha, that are controlled by this structure show that the ‘kink’ in the extension across Okataina caldera complex was active across Rotorua caldera during the collapse at 240 ka, and possibly earlier. This study shows the evolution of dyke-fed lava domes during eruption, and the control of regional structures in the location and timing of eruption. These findings improve our knowledge of the evolution of porosity and permeability in a compacting lava dome, as well as of the structures of Rotorua caldera, the longevity of volcanic activity at dormant calderas and the hazard potential of dyke-fed lava domes.

On 16 August 2014 an unusual sequence of earthquakes began near the southeastern rim of the ice-covered Bárðarbunga caldera in central Iceland. Over the course of two weeks a dyke propagated 48 km beneath the glacier northeastwards and into the Holuhraun lava field, where it erupted for six months, becoming the largest eruption in Iceland for over 200 years. During this time, a gradual, incremental caldera collapse took place in the central volcano. The rifting episode was captured both geodetically and seismically. In this thesis, I analyse the seismic response to the event, both due to the dyke propagation, and the subsequent caldera collapse. This gives an insight into the underlying processes controlling rifting events, and the nature of the responding crust. The Cambridge seismic network recorded the 2014-15 Bárðarbunga-Holuhraun rifting episode in exceptional detail. I discuss the deployment and operation of this dense seismic network in the remote Icelandic highlands, as well as the campaign deployments on the volcano caldera, on the glacier (above the dyke path) and around the eventual eruption site, as a first response to the crisis. Using this dataset I have accurately located, and analysed, 47,000 earthquakes during the pre-intrusive, intrusive, eruptive and post-eruptive periods. Approximately 4,000 of the recorded earthquakes are associated with the caldera collapse, delineating faults accommodating the subsidence and showing good correlation with geodetic data. The seismicity reveals activation of both inner and outer caldera faults with 60 inward dipping planes on the northern and southern side, indicating a symmetric caldera structure. Detailed analysis of the earthquake source mechanisms shows that 90% can be explained by a double-couple solution, which is in contrast to results from previous studies of Bárðarbunga. I find the dominant failure mechanism during the collapse to be steep normal faulting, with sub-vertical P-axes, striking sub-parallel to the caldera rim. The northern and southern sides of the caldera, however experienced very different seismicity rates, highlighted by the order of magnitude difference in the cumulative seismic moments. The southeastern part of the caldera, whilst experiencing less activity, shows a mixture of failure mechanisms, owing to the interaction of the caldera collapse and the dyke exit. Therefore, this thesis presents evidence of a complex asymmetric caldera collapse, not controlled by a single caldera ring fault. Of the 47,000 earthquakes located, 31,000 delineate the segmented, lateral dyke intrusion as it fractured a pathway through the crust, utilizing pre-existing weaknesses. Despite the extensional rift setting, the dyke emplacement generated exclusively doublecouple earthquakes. At the leading edge of the propagation, earthquake source mechanisms show exclusively strike-slip faulting, in contrast to the conventional model of normal faulting above a propagating dyke. I observe right-lateral strike-slip faulting as the dyke propagates to the NE, and an abrupt change to left-lateral strike-slip faulting as the dyke turns and propagates in a more northerly direction into the northern volcanic zone. This shows that the direction of fault motion is determined by the opening of the dyke, rather than by the regional extension. I am also able to define the thickness of the seismogenic crust under Bárðarbunga as 7 km, based on the depth extent of observed seismicity. The bulk of the seismicity in the volcano is located at 1-4 km below the surface, whereas the dyke exited the caldera at 4-6 km depth, propagating at 6-8 km b.s.l. I hypothesise that the magma storage region is likely located at 4-6 km b.s.l. (6-8 km below the caldera surface), just below the most active caldera seismicity and at similar depth levels to the dyke. Thus, this thesis details the melt distribution and movement at depth from a large basaltic central volcano, and the coupled deformation of the subsiding caldera with the dyke intrusion and eruption.

When creating a current work, artists cannot ignore the images that have preceded theirs. The history of a medium and the related history of subject matter is vital to the meaning of a new art work. Each sign and symbol has a connotation out of the artists’ control. The developed meaning of a symbol is inseparable for the viewer regardless of the acknowledgment of that meaning by the artist. To work with imagery and not address it’s historical context is to perpetuate it’s meaning. The only way to not state what has already been stated is to critically engage with the preexisting meaning of the imagery. An artist can combine symbols to create dual meanings or juxtapositions of meaning, or present the imagery in a way that complicates what it already signifies. “Apparent Fate,”my combined negative, photographic mural, uses imagery from Yosemite National Park to comment on photography’s function or purpose in history and in the current economic, political, environmental, and social conditions in California and society’s current stance on Manifest Destiny. How have the ideas of innate rights over people and places changed over time in American culture?

In order to understand the tectonic evolution of the Kalecik region (Ankara, Turkey), a structural field study was performed in a selected area located in the east of Kalecik, where mostly imbricated thrust sheets of the Cretaceous Ophiolitic melange crop out. In the study area, the Cretaceous Ophiolitic melange, Cretaceous radiolaria-bearing sequences and the Paleocene units are all intruded by sub-vertical dykes. The attitudes of planar structures (dykes, beds and faults) and the kinematic data measured on faults were analyzed by using &ldquo / ROCKWORKS 2002&rdquo / and &ldquo / Angelier Direct Inversion Method (version 5.42)&rdquo / softwares, respectively. A major trend of NE-SW (045&deg / N) direction and relatively a post-Paleocene &ndash / pre-Miocene age was determined for the dykes indicating an extension in the NW-SE direction during post-Paleocene. The dykes cut bedded units displaying a dominant set trending in WNW-ESE (297&deg / N) direction and mostly dipping towards NE with moderate dip amounts. But at the same time, the Upper Cretaceous units were observed as intensely folded, faulted and thrusted due to the compressional regime that acted in Central Anatolia during Late Cretaceous. The angular difference between the major trend of dykes and the dominant trend of stratification was found as approximately 108&deg / ., which may also indicate that the dykes and beds were evolved during different deformation periods. The results of the kinematic analyses of different age faults revealed that the post-Paleocene &ndash / pre-Miocene Kalecik basaltic dykes are deformed under a continuous NW-SE-oriented post-Paleocene compressional to strike-slip tectonic regime which was followed by a NNW-SSE oriented post-Miocene extensional-transtensional regime.

No description available.

The senseFly eBeePlus fixed-wing drone is a market available UAV compatible with a range of sensors that includes the Parrot Sequoia+ multispectral camera. Commercial applications of the drone predominantly focus on agriculture, environmental management, and engineering applications. The Sequoia 4-band multispectral sensor with bands optimised for plant health analysis, has a spectral range that coincides with the absorption features of iron. Previous studies with the use of hyperspectral sensors on multicopter UAVs have proven successful in the detection and delineation of hydroxides and sulphates associated with weathering of sulphides at the surface. This study aims to evaluate the ability of the eBeePlus drone equipped with a Parrot Sequoia+ sensor to effectively detect and delineate surficial sulphide mineral expressions by testing its capability on a known nickel-copper mineralisation occurrence at Illukunnguaq, on the north-western coast of Disko Island, West Greenland. Formally hosting a 28-tonne nickeliferous pyrrhotite massive sulphide boulder, many companies have sought this region for a possible extension of the mineralisation or another local mineral occurrence. Iron-feature band ratios and Spectral Angle Mapping (SAM) are two methods tested to first characterise the known occurrence, then search the wider region for other features with a similar signature as the Illukunnguaq dyke. To assist the evaluation and fine tune the Sequoia sensor, it will be compared against the trialled and trusted Rikola hyperspectral sensor, proven to map iron features. In addition, eigen maxima as one of many geomorphological indices that utilise the co-product Digital Surface Model (DSM) of the spectral survey, is employed to assess whether the Illukunnguaq dyke and other features are structurally mappable.  Results show that the Sequoia multispectral sensor, albeit less spectrally resolved than the Rikola hyperspectral sensor was able to detect surficial sulphide mineral expressions both by applying iron-feature band ratios and SAM. The latter was performed using laboratory measured and open-access library spectra. To fine-tune the tools compatible with the Sequoia sensor, in-depth investigations into iron-feature band ratio index values and best-fit library spectra for SAM was conducted. Confidence was increased by the blind detection of another known exposure and permitted a regional search to find additional features with spectral similarities to the Illukunnguaq dyke for future ground truthing. This study demonstrates that the eBeePlus drone can be used for mineral exploration when iron-sulphides are a part of the mineral system and outcropping at the surface. Leading field programs with detailed multispectral mapping can improve the efficiency of geologists by generating or verifying targets prior to ‘boots-on-the-ground’ geological sampling or mapping.