1 10 65 https://theses.otagogeology.org.nz/files/original/40619c3286d9edb8d245714002bffd36.pdf 9fe3de378391b7aab72618dbff57f2e1 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((171.951066336025 -42.3392437657565,171.945269977672 -42.3401437250807,171.932645245355 -42.3269689228649,171.932483457731 -42.3213439037579,171.938960362076 -42.3180680379941,171.954485088648 -42.3345093104671,171.951066336025 -42.3392437657565)),((171.907811478265 -42.2198398151223,171.902042032984 -42.2197847303217,171.888666886462 -42.2092188751299,171.890640984123 -42.2063070331894,171.893632442448 -42.2056925470364,171.907865676327 -42.2166949227961,171.907811478265 -42.2198398151223))) Author last name Last name of the Author Malloch Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Craw, D. Abstract The Abstract for this thesis Orogenic gold deposits are a source of arsenic (As) and antimony (Sb), in the sulphides arsenopyrite and stibnite respectively. Weathering of these deposits releases As and Sb into the environment but it is ore processing that can concentrate naturally occurring As to Sb to toxic percentage levels. Gold recovery by mercury (Hg) amalgamation and cyanidation results in the addition of metals (zinc (Zn), lead (Pb) and Hg)) and chemicals (cyanide) that can also be concentrated during processing to high levels that exceed national guidelines. Through the practice of crushing and milling during processing, fine (< 500 ?m) metal-rich particles are produced that are easily transported by rain splash and wind, and easier to inhale and ingest. This study examines three historic processing sites in the Reefton Goldfield, New Zealand that operated prior to the 1950s when legislation was not in place requiring the remediation of a site after closure. These abandoned processing sites contain historic relics that are of an interest to the Department of Conservation (DOC) to preserve on these heritage sites, as well as containing high metal processing residues that are a potential environmental concern. Of the three sites presented in this study, the toxic As(III) arsenolite in the Edwards roaster at the Alexander processing complex poses the highest hazard. The extreme As levels (in excess of 35 wt% As) are the result of ore roasting to release refractory gold from sulphides, and these extreme As levels are seen at other historic processing sites where the ore was roasted. Crystalline efflorescences inside the Edwards roaster may indicate that As vapours permeated the structure during roasting and are now a point source for As. Ore roasting has also concentrated other metals (Sb, Hg) in the roaster to high levels. High metal levels on the three sites studied are largely sequestered by the formation of secondary iron arsenate and iron oxide minerals. Any dissolved metals leaving the sites are diluted by high regional rainfall. The weathering of sulphides, concentrated by ore processing, has resulted in the localised production of acid but lime added during processing, as well as carbonates in the Greenland Group host rocks, neutralises the acid so there is no acid mine drainage (AMD). There is no significant increase in dissolved metals downstream from the Alexander processing complex, with most metals below detection limits and all metals well below the New Zealand drinking water standards. Previous site investigations into historic processing sites in the Reefton Goldfield, and this study, highlight the importance of undertaking a thorough investigation of metal distribution, speciation and mobility before deciding on a site remediation plan. Ranking of a site for remediation should take into account its land use and future land use, as well as visitor numbers and levels of exposure. On the basis of the processing residue’s mineralogy and geochemistry at the three sites presented in this thesis, it is recommended that due to the remoteness of these sites and low visitor numbers, that they are a low priority for remediation. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7047">http://hdl.handle.net/10523/7047</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Alexander Mine West Coast Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2017Malloch Creator An entity primarily responsible for making the resource Malloch, Kirstine Date A point or period of time associated with an event in the lifecycle of the resource 2017 Title A name given to the resource The Environmental Legacy of Historic Gold Processing in the Reefton Goldfield Subject The topic of the resource Environmental Geology Alexander mine amalgamation arsenic arsenolite Golden Lead mine lead mercury ore roasting pharmacolite yukonite zinc https://theses.otagogeology.org.nz/files/original/25e16402c3267f6f46f5c306f0531a49.pdf 84edb9c93cee05cc41b3f3ae249260e3 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((171.939600371393 -42.145297664106,171.980022840865 -42.1454854474944,171.979792325286 -42.1740213276647,171.939351690887 -42.1738332591177,171.939600371393 -42.145297664106))) Author last name Last name of the Author Partridge Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Craw, D. Pope, J. Trumm, D. Abstract The Abstract for this thesis Acid mine drainage (AMD) is one of the most important environmental issue arising from mining practices worldwide. It is caused by the disturbance, and then chemical weathering of pyrite rich rocks during mining operations. AMD is characterised by low pH (2-3) and increased metal concentrations, occasionally reaching toxic levels for humans. Extensive research has been undertaken world wide to prevent and combat AMD through proper identification of pyrite formation, oxidation, chemical weathering of other phases, and subsequent discharge chemistry. In New Zealand, especially on the West Coast of the South Island, a rich history of coal mining since the 1800s has caused environmental issues arising from AMD that have been studied by many authors, leading to remediation and prevention plans, and a better understanding of the constraints on AMD production. Echo mine is a recently active coal mine that as of the end of this thesis, has moved into a “care and maintenance” mode. It produces coal mined from the acid forming Brunner coal measures. AMD is observed at the site, with elevated levels of Fe, Al, Mg, Ca, SO42- , and trace elements such as Ni and Zn. This thesis represents research undertaken to identify the main cause of AMD, how mine wastes change while stored, and the secondary phases responsible for any temporal and spatial changes in AMD chemistry. Fieldwork at the mine revealed 3 main rock types, all of which contribute to mine wastes - a white sandstone, a grey mudstone and a rare blue/green sandstone. Samples of these were collected and their mineralogy and geochemistry identified. The white sandstone was only potentially acid forming (PAF) rocks, while the mudstone provided a source of soluble iron in the form of a hydroxide matrix and minor alkalinity in the form of post-depositional cross cutting Mn-bearing ankeritic veins. The blue/green mudstone contains dolomite and Mn-ankerite, representing the main source of alkalinity at the site. Samples of precipitates from the surface of rocks were collected and analysed to determine the phases present. Jarosite was frequently observed on the surface of the white sandstones, while amorphous iron hydroxides were present on the mudstones. These represent a considerable source of long term acidity storage at the site, and need to be taken into account when creating a long term remediation plan. The site provided access to mine wastes of three different ages - 2, 5 and 12-15 years old. These were “autopsied” with horizons selected based on appearance and analysed to determine the phases responsible for the changes observed, titratable actual acidity (TAA) and HCl soluble sulfur (S HCl), and the water soluble mineralogy and geochemistry determined. XRD patterns for both crushed and sieved samples returned identical patterns for all samples, suggesting differences between them was either below detection or amorphous in nature, therefore XRD was not of use. TAA levels progressively increased over time. S HCl levels were initially high at intermediate depths. Over time, concentrations increased at the surface and deeper in mine wastes. Saturation indices calculated from PHREEQC suggested schwertmannite, jarosite and rarely alunite and amorphous Fe(OH)3 were all over saturated, while most phases remained below saturation. Temporal changes were observed, with highest dissolved metals and lowest pH observed in the 5 year old wastes, with Mn, Ni, Zn and Mg sharply decreasing after 5 years, interpreted to be due to the epsomite solid-solution series having high solubility, coupled with a limited supply of these constituents. During sample storage, a small hole developed on one of the sample bags, allowing cold, humid air to circulate around the sample. This produced an efflorescent bloom, which was analysed to determine the mineralogy. A combination of XRD and SEM analyses determined gypsum, epsomite, alunogen and mirabilite were present. This information was used as a basis for the changes in water soluble chemistry collected from horizon leaches. The water soluble chemistry of the mine wastes were normalized and modelled using PHREEQC to determine the paragenesis of phases during evaporation. Most samples produced jarosite and gypsum, with schwertmannite over saturation ending after equilibration of the solution. Surprisingly, no epsomite, alunogen or mirabilite was formed, most likely due to the accidental nature of their precipitation. Several trends were observed during evaporation modelling, with phases either increasing saturation, decreasing, or showing an increase then decrease. Increases were related to increased activity of dissolved species, while negative trends were attested to decreased [OH-]. The increase then decrease trend was not explainable, and is most likely an artifact from PHREEQC modelling. Overall, recommendations can be made against the moving of mine wastes in the first 5 years of storage, due to the increased dissolved metal activity reaching a maximum at this point. However, since long terms of acidity migrate to shallower levels over time, the nature of sulfate controlled acidity changes from rapid to slow releases over time. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/6916">http://hdl.handle.net/10523/6916</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Reefton West Coast Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2016Partridge Creator An entity primarily responsible for making the resource Partridge, Taliesen (Tal) Date A point or period of time associated with an event in the lifecycle of the resource 2016 Title A name given to the resource An investigation into the primary and secondary causes of and controls on acid mine drainage at Echo Mine near Reefton, New Zealand Subject The topic of the resource Environmental Geology acid mine drainage Evaporation modeling New Zealand PHREEQC Sulfate mineral https://theses.otagogeology.org.nz/files/original/69b44a6f1067eb1a446d88657b64cb72.pdf 17ab854a5c6939c7e78e49a0996029e2 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((170.409813383736 -45.3392144728741,170.501578657676 -45.3412599512349,170.499002911411 -45.3996965301032,170.407143285844 -45.397646902954,170.409813383736 -45.3392144728741))) Author last name Last name of the Author Farmer Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Craw, D. Abstract The Abstract for this thesis Tungsten mineralisation within the Otago Schist is hosted by hydrothermal quartz veins that formed close to the brittle-ductile transition zone. The Otago Schist Belt hosts numerous orogenic gold deposits, including the Macraes mine, a number of which also host the tungsten ore mineral scheelite. Despite the strategic importance of tungsten, no commercial mining of scheelite in Otago has occurred since the 1960s, and the Macraes operation does not recover tungsten despite mining tungsten ore. This study examines the spatial and temporal relationships between gold and tungsten from a microscopic up to a deposit scale, focusing on the Macraes deposit and applying the findings to the wider Otago region. Understanding this relationship is essential for modelling and extracting tungsten in Otago, and in the exploration for new deposits. Macraes’ tungsten is predominantly found within mineralised quartz veins, although a subordinate phase of disseminated scheelite and a remobilised phase are also observed. Ductile microstructures and the cross-cutting relationships observed within the veins suggest that the main phase of tungsten mineralisation occurred early in the development of the deposit. The style of tungsten mineralisation contrasts strongly with that of gold at Macraes, which is disseminated throughout the pervasively altered wall-rock, and which is contemporaneous with both brittle and ductile structures. This relationship is echoed throughout the deposits in Otago: tungsten mineralisation is found within veins that formed at depth within the crust while gold is found associated with both deep and shallower structures. The extent of tungsten mineralisation was determined in a section of the Macraes mine using Portable XRF (pXRF). This approach identified a 200 m by 80 m pod of tungsten mineralisation coinciding with a jog in a mineralised shear, suggesting that mineralisation is associated with the opening of large-scale dilational sites. Evidence from the Nd and Sr isotope signatures of the Macraes scheelites suggest that the source mineralisation at Macraes was the schists of the Torlesse Terrane. The data favours a model of a metamorphic source of mineralisation, in which dewatering of the schist under amphibolite facies conditions produces hydrothermal fluid, which leaches metals from the schists as it ascends through the crust. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/6700">http://hdl.handle.net/10523/6700</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Macraes Mine North Otago Otago Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2016Farmer Creator An entity primarily responsible for making the resource Farmer, Lauren Date A point or period of time associated with an event in the lifecycle of the resource 2016 Title A name given to the resource The temporal and spatial relationship between tungsten and gold mineralisation in the Otago Schist, New Zealand Subject The topic of the resource Exploration Geology Macraes Otago Schist scheelite tungsten https://theses.otagogeology.org.nz/files/original/f5cc77cc64d8e790b1fb065244349860.pdf 9b12c00415da53d6f0b29f52a3938748 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((169.449001255111398 -45.233334970424167,169.446825321401917 -45.278995759185221,169.381480173370534 -45.277417866292026,169.39850970053277 -45.232228257690274,169.449001255111398 -45.233334970424167)) Author last name Last name of the Author Yeo Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Craw, D. Mackenzie, D. Scott, J.M. Abstract The Abstract for this thesis A zone of brittle faults, hosted within the Otago Schist occurs along the NE- trending margin of the Manuherikia valley in Central Otago. The faults were initiated in the Cretaceous with predominantly normal sense of motion. Some faults have been reactivated as reverse structures since the Miocene, offset- ting gold-bearing Cenozoic sediments. Quaternary reactivation has resulted in stepped topography adjacent to the Manuherikia River. Cretaceous fault activity was accompanied by hydrothermal fluid flow and minor alteration of fault rocks and adjacent wall rocks. There are three different styles of faulting within the Tucker Hill area: narrow E-W orientated silicified zones, wide NE-SW orien- tated silicified cataclasite zones, and carbonate-rich, orange-stained zones. The narrow E-W oriented silicified zones have 5-10 cm wide silicified cataclasites along the fault plane, and these dominate the southern end of the area. Some of these zones host veins with euhedral crystals of calcite and quartz. These nar- row zones have a wide range of orientations, often show cross-cutting relation- ships with other faults and are traceable for only short distances (<100 m) along strike. Farther north in the area, wide resistant, silicified slabs of cataclasite, be- tween 2-4 metres across, form resistant ridges across topography. These zones are well exposed, with prominent fault planes containing slickenlines which pre- dominately show a dip-slip sense of motion. These large resistant faults range from moderately to steeply dipping and are largely orientated NE-SW. Inferred fault zones are prominently orange-stained where Fe-rich calcite has been al- tered to limonite, and form easily-eroded lower topographic features within the area such as gullies or saddles between ridges. These inferred fault zones are often associated with remnant Miocene, Dunstan Formation sediments. Some of the inferred zones occur along the same strike as the wide silicified catacla- site zones. Scattered pyrite occurs in some silicified rocks, and there are low but anomalous levels of arsenic and gold in some fault rocks. Two morphologically distinct types of Otago Schist basement have been described at Tucker Hill. The southern section contains a TZIII ”slabby” schist, whereas the northern section has a TZIV ”folded” schist. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/6138">http://hdl.handle.net/10523/6138</a> OURArchvive access level Open Access Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Manuherikia Fault Zone Alexandra Central Otago Thesis description Number of pages, maps, CDs, etc. xiv, 120 pages A4, A1 map in back pocket folded Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2015Yeo Creator An entity primarily responsible for making the resource Yeo, Samantha Louise (Sam) Date A point or period of time associated with an event in the lifecycle of the resource 2015 Title A name given to the resource A Structurally Controlled Hydrothermal System in the Manuherikia Fault Zone, Alexandra, Central Otago Subject The topic of the resource Metamorphic geology Metal-ore depsoits Fault Zone mineralisation Otago Schist https://theses.otagogeology.org.nz/files/original/8d67f50f02de365aa98b130dd7aa9fd8.pdf 162e7c43bf18e60349c0510b50ed69b4 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((172.720715606122013 -41.0531463765194,172.819863327854279 -41.052890961980104,172.815562664355696 -41.092751433143683,172.716554001543926 -41.093154460720861,172.720715606122013 -41.0531463765194)) Author last name Last name of the Author Phillips Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Craw, D. Abstract The Abstract for this thesis Gold mineralisation at Sams Creek occurs within an under-explored region with a rich history of alluvial gold prospecting dating back to at least the 1850s. Gold at Sams Creek is structurally hosted by sheeted veins and irregular fractures in an A-type peralkaline microgranite dike which extends 7km along strike and is up to 60 meters in thickness. The deposit was first discovered by CRA Exploration and was then further explored by OceanaGold, currently in a joint venture with MOD Resources. The majority of exploration has been conducted in the “Main Zone” including over 120 diamond drill holes. At least three stages of hydrothermal activity have altered the dike including the precipitation of late arsenopyrite veins, and lesser amounts of pyrite, sphalerite, galena, and gold. Scanning Electron Microscopy (SEM) is used to show that gold occurs as an alloy with silver (~80-85% Au) as small growths (up to 40 μm) with pyrite and base metal sulphides. These phases are primarily found cementing and in-filling fractured and brecciated arsenopyrite (the most abundant “ore mineral”). A reduced assemblage characterises the unaltered peralkaline microgranite dike which undergoes its first alteration (T1) under relatively oxidizing and ductile conditions during a late magmatic stage. Later, structurally controlled vein-related alterations (T2, T3, & T4), tied to regional deformation, occur under reduced and brittle conditions. Microstructural deformation during these stages is primarily characterised by a combination of extensional and shear related features. This study isolates geochemical enrichments related to specific alteration and vein assemblages from analysis of a targeted, independent sample set collected for this research. Using exploration generated assays, from 1 m half-core sampling a kilometre of vertical relief, this study also defines spatial distributions and variations in geochemical signatures throughout the deposit scale. A Au-As-Sb assemblage is anomalous over the full scale of the deposit, and zoning patterns of Ag, Pb, and Zn are observed throughout the full range of elevations sampled. Most notably, Ag increases with elevation, while Pb and Zn increase with depth. Mo is also relatively elevated at depth. Hydrothermal zircons first reported by Nazimova (2012) occur as clusters and stringers of <1-15μm anhedral crystals along grain boundaries of arsenopyrite and within the same micro fractures which gold grains occupy. These zircon are interpreted as forming from hydrothermally dissolved and reprecipitated zirconium present in the unaltered Sams Creek Dike. Zircons also occur in un-mineralised samples as larger ellipsoidal to faceted individual grains associated with primary mafic minerals and are interpreted as magmatic in origin. These zircons are up to ~25μm in size and many grains exhibit a spongy dissolution(?) texture. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5119">http://hdl.handle.net/10523/5119</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Sams CreeK NW Nelson Thesis description Number of pages, maps, CDs, etc. xiv, 177 pages A4 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2014Phillips Creator An entity primarily responsible for making the resource Phillips, Markham Date A point or period of time associated with an event in the lifecycle of the resource 2014 Title A name given to the resource Geochemistry & Timing, Sams Creek Gold Deposit NW Nelson, New Zealand Subject The topic of the resource Geochemistry Exploration Geology exploration geochemistry Geology gold Hydrothermal Zircon Northwest Nelson Sams Creek U-Pb Dating https://theses.otagogeology.org.nz/files/original/0327a2fe669e280d3833a4c7e8249f5b.pdf 26b873cccc26690cb198514393062928 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((168.451224660724904 -44.885898033364391,168.393783591749468 -44.883590800942457,168.401627872702107 -44.852468047135432,168.459188203246185 -44.852870628255161,168.451224660724904 -44.885898033364391)),((168.911755815476226 -44.798070303351658,168.899281276576318 -44.917188240482815,168.746940966482981 -44.910177645629553,168.759482258347845 -44.794413468896266,168.911755815476226 -44.798070303351658)),((171.916010761828943 -42.250280043141132,171.889992922875564 -42.250635086608682,171.889603128360449 -42.238100068707311,171.916014349335171 -42.238201758443743,171.916010761828943 -42.250280043141132)),((171.899277154527425 -42.163255769324884,171.898684573549104 -42.175259918662931,171.882938502706537 -42.174392794247062,171.882553225204816 -42.163523004393006,171.899277154527425 -42.163255769324884))) Author last name Last name of the Author Druzbicka Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Craw, D. Pope, J. Abstract The Abstract for this thesis Mining activities inevitably result in changes to the environment and have the potential to cause negative impacts. This work investigates and emphasises the role of geology as the primary control on the environmental issues related to mining activities, whether current or historic. The knowledge and understanding of geological and geochemical factors associated with a particular deposit is crucial in ensuring the prevention and/or minimisation of the environmental impacts of mining operations. Such knowledge is essential for the responsible environmental management of mines. The research presented in this thesis is applied in nature and focuses on mesothermal and associated placer gold deposits located in the South Island of New Zealand. Arsenic and antimony are two metalloids commonly associated with mesothermal deposits, where they are mainly present as minerals arsenopyrite and stibnite, respectively. The mobilisation of these metalloids from deposits is facilitated by near-neutral pH and the greenschist facies rocks hosting mesothermal deposits are characterised by generally high acid neutralising capacity thanks to the presence of carbonate minerals. Arsenic and antimony are known for their toxicity at low levels (e.g. < 0.01 mg/L in water) and therefore their elevated concentrations in waters and solid mine residues and soils are the main environmental concerns with regards to the mining of mesothermal deposits. The presence of metalloids has been studied as part of this work in both active as well as historic mining settings in four different locations. At the active Globe Progress mine in the West Coast, metalloid signatures of mine waters were found to have evolved from Sb/As < 1 to above 1 suggesting that the mobilisation of antimony has proportionally increased with regards to arsenic over the course of over two years since the mine’s opening. The impact of metalloids on aquatic fauna was investigated in a long-term field study and not enough evidence was gathered to suggest their involvement in the decrease in the ecosystem’s health which was found more likely to be attributable to the repeated increased turbidity events in the receiving stream. The choice of mining methods as well as climate as a factor in determining the environmental aspects is also recognised here with the change in mining method from underground to open cast being responsible for the change in the type of ore mined and therefore also the related metalloid signatures. An historic mining processing method of roasting of sulphide-rich ore (especially in an Edwards roaster including an As saving system) was found to influence the mobility of metalloid-bearing mine residues governed by the presence of soluble arsenolite and immobilisation of metalloids through the formation of relatively stable secondary minerals at sites where no roasting in the Edwards roaster has been performed in the past. For example, immobilised As and Sb-bearing residues at the Big River mine were found to contain up to ~20 wt% As and 3.5 wt% Sb. The presence of localised acidic pH conditions was recognised as an important control on the immobilisation of metalloids, ensuring the stability of some of the secondary mineral phases (e.g. scorodite). Turbidity or suspended solids load in waters has been a major environmental issue in New Zealand since the beginning of mining operations in the country. Even though the problem is widely-recognised, not much is known with regards to what controls the levels of turbidity produced and their rates of settling. The geological factors recognised as important in the study of five paleoplacer deposits from Central Otago include the abundance of clay minerals, which is partially dependant on the presence of altered basement rocks in the Central Otago setting as well as the mode of transport and deposition of the sediments. Additional physical factors such as the level of cementation of a deposit were also found to be an important control on turbidity production and dissipation. The appropriate management of active mine sites is crucial in ensuring that the activities are performed in as safe a manner as possible from the environmental point of view. Today, modern mines operate extensive environmental management and monitoring systems and actively work towards improving the existing schemes. The evaluated waste rock management system at the Globe Progress mine, designed to help keep the metalloids on site and prevent their release via waters percolating through waste piles, was found to be working well. Overall, the system correctly categorises waste rocks into two types depending on their predicted arsenic content, and therefore their level of environmental sensitivity, followed by correct handling and storage in appropriate waste piles. The management of historic sites involves the evaluation of their environmental impact on the local environment which should also include an assessment of any potential health and safety risks with regards to the visiting public, which is not always considered at historic sites in New Zealand. In addition, a potential conflict between historical preservation and environmental management has been recognised. On the other hand, the widely-perceived conflict between mining and conservation values has been demonstrated to not always be the case with examples of unique saline habitats forming at two historic placer mining sites in Central Otago. The natural rehabilitation of these sites was found to contribute to the enhancement of the sites’ long-term biodiversity suggesting that natural succession may be important for the establishment of stable and robust ecosystems. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/4915">http://hdl.handle.net/10523/4915</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. West Coast Globre progress mine South Island Central Otago Thesis description Number of pages, maps, CDs, etc. xxvi, 2 Parts, 560 pages A4 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2014Druzbicka Creator An entity primarily responsible for making the resource Druzbicka, Joanna Barbara (Asia) Date A point or period of time associated with an event in the lifecycle of the resource 2014 Title A name given to the resource Geological controls on environmental impacts and management strategies for mined mesothermal and placer gold deposits Subject The topic of the resource Environmental Geology environmental gold mesothermal metalloids mining placer https://theses.otagogeology.org.nz/files/original/8199aab14f138b54dcfb8693265bde2b.pdf f81ac76ffb59d7629b93a464de823189 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((169.359776841146925 -45.259080422426123,169.347242996690483 -45.440877800715739,169.07632715220754 -45.432475295790731,169.088081758988864 -45.250084752184293,169.359776841146925 -45.259080422426123)) Author last name Last name of the Author Stephens Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BAppSci(Hons) Advisers Who supervised/advised this student Craw, D. MacKenzie, D. Abstract The Abstract for this thesis Six structurally controlled gold deposits are hosted within two different structural blocks in the Old Man Range area. The mineralised lodes are hosted in normal faults which cut steeply across the host schistosity. In the East structural block, mineralised faults and the prominent joint set strike northwest and cut steeply across greenschist facies TZ III Caples Terrane schist. In the West structural block, mineralised faults and prominent joint sets strike east-west and cut steeply across upper-greenschist facies TZ IV Wanaka lithologic association schist. These structural blocks are separated by the regional scale Old Man Fault. Orientation of hard rock gold deposits is closely linked to the prominent joints in host schist surrounding the deposits. Mineralised lodes formed along ~1m wide normal fault zones. They are discontinuous but can be traced for up to ~150m, with variable thickness along strike. The lodes comprise brecciated silicified schist and hydrothermal quartz breccia, and minor quartz veins with abundant arsenopyrite. Open cavities with euhedral quartz crystals are common. Euhedral arsenopyrite occurs in quartz and silicified schist clasts within mineralised zones. Gold occurs as micro-particulate blebs in partly oxidised arsenopyrite, and as coarser free grains within quartz, micaceous laminae, micro-faults, and micro-shears within mineralised rock. Hydrothermal alteration is minor, comprises addition of Si, Au and As, and extends only a few centimetres from the mineralised lodes. Mineralisation may have occurred within a few kilometres of the surface during mid-Late Cretaceous extension (~106-101Ma), with estimated formation temperatures between 200-350°C. The mineralised structures within the Old Man Range area are similar to other shallow level, post-metamorphic Otago gold deposits. Magnetic, magnetite bearing greenschist has a high magnetic response and can be successfully mapped using total magnetic intensity surveys over the Old Man Range area. Electromagnetic (EM) surveys can be used successfully to map post-metamorphic faults within the Old Man Range area, where they show up as linear conductive anomalies. These geophysical surveys are a useful tool for geologic mapping. However, there is no direct link between the geophysical features and gold mineralisation within the Old Man Range. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Old Man Range Otago Thesis description Number of pages, maps, CDs, etc. v, 112 pages A4 map in back pocket A1 OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7295">http://hdl.handle.net/10523/7295</a> OURArchvive access level Open Access Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2013Stephens Creator An entity primarily responsible for making the resource Stephens, Samuel (Sam) Date A point or period of time associated with an event in the lifecycle of the resource 2013 Title A name given to the resource Characterisation of Gold Mineralisation and Geophysical aided Geologic Mapping in the Old Man Range, Central Otago, New Zealand Subject The topic of the resource Ore Deposits EM gold Magnetics schist veins https://theses.otagogeology.org.nz/files/original/a35c4d7120ba6360e3d4b4843a9c1a88.pdf 31bfb8c8d76f1213e08788d52f012aaf Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((169.866396627725351 -45.133923088606338,169.871963387087959 -45.124429863111018,169.892429392666003 -45.128561705121918,169.87646731121842 -45.162065329313592,169.852559779917243 -45.156049465566348,169.866396627725351 -45.133923088606338)) Author last name Last name of the Author Stewart Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PGDipSci Advisers Who supervised/advised this student Craw, D. McKenzie, D. Abstract The Abstract for this thesis A set of more than 30 mineralised normal faults and associated fractures cuts upper greenschist facies textural zone 4 Otago Schist between the North Rough Ridge and Rough Ridge drainage divides near Garibaldi Diggings, Central Otago. The mineralised structures strike northeast and dip steeply (60•) to the northwest. The zone of mineralisation is intense and occurs as a swarm of veins within a well defined area under 1 km2. Mineralised structures contain 1 cm to 1.8 m thick quartz veins which are traceable as an intricate network of structures for several meters along strike. In the near surface the mineralised structures are hosted within a thick zone of kaolinitized greenschist which developed beneath a regional unconformity surface and an overlying suite of auriferous terrestrial sediments. The thick zone of alteration forms a low northeast trending ridge and is heavily stained by secondary iron and manganese oxides. The source of the iron oxides may be due to the breakdown of iron bearing sulphide minerals within the mineralised structures or the oxidation of associated hydrothermal ankerite. Alternatively the breakdown of chlorite within the westerly dipping greenschist layer could also provide a source for the iron oxides. Quartz veins contain abundant breccias with variably altered clasts of quartzofeldspathic schist. The veins contain sparsely distributed scheelite mineralisation although no sulphide minerals can be observed in hand specimen due to the intense alteration within the host greenschist layer. Hydrothermal alteration of the host greenschist layer adjacent to veins cannot be differentiated from alteration developed beneath the regional unconformity surface due to the pervasive nature of this alteration. The normal faults and associated fractures of the Garibaldi vein swarm developed during middle to late Cretaceous extension whicih accompanied the uplift and exhumation of the Otago Schist belt. The vein swarm at Garibaldi may share affinities with the Manuherikia Fault Zone; a major northeast striking fault zone on the east side of the Manuherikia Valley, Central Otago. Detrital gold grains collected from both the Miocene and Quaternary paleoplacers at Garibaldi Diggings have secondary gold structures preserved on their surface. There is a consistency in morphology and surface textures displayed by detrital gold grains collected from the Garibaldi and Dell Creek placer deposit in the Lower Nevis Valley, Central Otago. The Garibaldi and Dell Creek placer deposits represent two separate parts of the Central Otago alluvial gold system. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Garibaldi goldfield Thesis description Number of pages, maps, CDs, etc. 79 pages : illustrations, maps, 2 folded maps and 4 sheets in pocket ; 30 cm. + 1 CD-ROM (4 3/4 in.) Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2012Stewart Creator An entity primarily responsible for making the resource Stewart, James Alistair Date A point or period of time associated with an event in the lifecycle of the resource 2012 Title A name given to the resource Characteristics of gold bearing quartz veins at the historic Garibaldi goldfield, Central Otago, New Zealand Subject The topic of the resource Map structural geology central Otago alluvial gold Garibaldi goldfield gold https://theses.otagogeology.org.nz/files/original/08c0cac01674303f2afa24285a15492c.pdf 7ca621036d7822c1995d82f86e90b85b Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((168.74540988287643 -46.11762385949563,168.829384533173027 -46.121200483386197,168.826833159684696 -46.163974867612822,168.744160753425575 -46.160445139053117,168.74540988287643 -46.11762385949563)) Author last name Last name of the Author Falconer Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Craw, D. Reay, A. Abstract The Abstract for this thesis The development and evolution of supergene gold and sulphide mineralisation that occurs in quartz pebble conglomerates (QPCs) from two contrasting environments is investigated. The contrasting sites in this study represent a progression in the development of supergene conditions that occur in relatively high energy fluvial settings. Mineralisation at two separate localities from a Miocene-Pliocene aged QPC in southern New Zealand is examined in detail. In contrast to this, gold mineralisation from an Eocene aged palaeochannel from the deeply weathered lateritic regolith of the Yilgarn Craton, West Australia, is also investigated. Although from vastly different geological settings, both occurrences of supergene mineralisation are in fluvial environments characterised by anomalous gold (Au-Ag alloy) and fine-grained diagenetic sulphides. Given the analogous fluvial environments, they have undergone similar processes and consequently a more complete picture of gold and sulphide diagenesis has been built up. A number of gold precipitation and dissolution textures are distinguishable in the active supergene environment at Belle-Brook (New Zealand). Precipitation textures include a variety of semi-spheroidal gold forms that are variously aggregated, budded and occasionally crystalline. Dissolution textures are associated with the loss of Ag from the Au-Ag alloy and are characterised by preferential grain boundary dissolution along subgrain boundaries. Fresh dissolution textures are observed as a well-defined line occurring between subgrains, however with increasing evolution and modification to the surface early textures are often obliterated. The diagenetic sulphide suite at Belle-Brook shows a progression of sulphide diagenesis from detrital sulphides through to fine-grained framboidal pyrite and spheroidal marcasite that may also develop into a pervasive cement or large (cm’s) lumps. The low pH surface waters at Belle-Brook preclude the oxidation of these sulphides to goethite. The sulphide suite is predominantly marcasite in which extensive precipitation periodically occurs most likely in response to fluctuating redox conditions associated with the alluvial mining operation that occurs at the site. At Sunrise Dam coarse-grained chunky palaeochannel gold is interpreted to be supergene. A high-grade hypogene source intersects the palaeochannel and hypogene gold is observed but is readily identifiable based on morphology. Supergene gold in the palaeochannel occurs as distinctive highly irregular grains characterised by embayments associated with detrital quartz grains, or filled with clays that host fine-grained microcrystalline gold. Episodic gold precipitation is inferred from microcrystalline gold that forms lineations or bands. Fluctuating redox conditions are most likely responsible for what may be episodic gold precipitation. In the hypersaline lateritic regolith at Sunrise Dam, gold is strongly redox controlled as indicated by enrichments associated with palaeo-redox fronts. With evolving aridity associated with the change in climate from wet and tropical in the Eocene, to the present arid climate, the resultant drying out of the profile and lowering of redox fronts has resulted in a redistribution of gold enrichment and depletion zones. With the exception of fine-grained marcasite and pyrite preserved in the reduced basal lags of the palaeochannel, these changing redox conditions have resulted in the oxidation of the original diagenetic sulphide suite to goethite and iron-rich clays. Whilst entirely supergene gold particles are rare in the QPCs in New Zealand, they are common in the palaeochannel at Sunrise Dam where there is a nearby high-grade hypogene gold source. Despite a lack of hypogene source, examples of entirely supergene gold do occur in the QPCs indicating that in very specific environments supergene conditions are conducive for mobilising and precipitating significant amounts of gold. In contrast to the lateritic regolith where supergene processes are responsible for and control gold enrichment, physical processes are the most significant for gold enrichment in QPCs from New Zealand. The main site at Belle-Brook is characterised by actively occurring supergene processes and as such provides valuable insight into early diagenetic processes that are often obscured or not preserved in other more modified settings. This study finds that gold in the supergene profile behaves in a similar fashion, regardless of whether it occurs in an arid weathered regolith profile in Western Australia or a quartz pebble conglomerate gold placer in southern New Zealand. Morphological features and geochemical textures on gold from all sites indicate that electrochemical refinement of the Au-Ag alloy is a major processes that drives the coupled dissolution and precipitation of gold that occurs in the supergene environment. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/1880">http://hdl.handle.net/10523/1880</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Southland and Western Austrailia Thesis description Number of pages, maps, CDs, etc. 1 v. (various pagings) : col. ill ; 30 cm. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2011Falconer Creator An entity primarily responsible for making the resource Falconer, Donna Marie, 1965- Date A point or period of time associated with an event in the lifecycle of the resource 2011 Title A name given to the resource The development and evolution of supergene gold and sulphide mineralisation in quartz pebble conglomerate deposits. Subject The topic of the resource Placer gold deposits gold mineralisation supergene gold supergene sulphides https://theses.otagogeology.org.nz/files/original/59edcdd143aeee46e7b37271f7c32ff6.pdf 82471891eb0161c37d53744d56f76747 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Blackler Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PGDipSci Advisers Who supervised/advised this student Craw, D. Abstract The Abstract for this thesis Studies of scheelite-sulphide rich ore from Macraes Mine, East Otago, New Zealand illustrate important relationships in terms of their spatial distribution and separation from each other. Understanding this relationship by observing the structural and geochemical inter-relationships between gold and tungsten, using arsenic as a proxy for gold has important economic implications in regards to wheather both gold and and scheelite (as a by-product) can be extracted together effectively. Past work has identified this as a possibility in a similar geological environment. With the aid of UV-light, XRF, Microprobe and LA-ICP-MS techniques, results show a clear separation between arsenic (+ gold by association) and scheelite. Sulphides are distributed widely and occur at most concentrated levels within shears or micro-shears. They also appear on the edges, or even sometimes within the quartz-scheelite veins. This would suggest for at least one generation, mineralisation of sulphides and scheelite occurred together. This study has identified that although in parts of the Macraes Deposit, there is a close relationship regarding the distribution of sulphides and scheelite, there is still the spatial separation as would be expected. Further work, ostensibly involving crushing size, will most likely be the important factor in terms of understanding the most effective way of beneficiating scheelite from the overall ore, followed by beneficiation of any remaining sulphides from within the scheelite itself. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Macraes Mine East Otago Thesis description Number of pages, maps, CDs, etc. 72 leaves : ill. (some col.), maps ; 30 cm Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2011Blackler Creator An entity primarily responsible for making the resource Blackler, Timothy Graeme Date A point or period of time associated with an event in the lifecycle of the resource 2011 Title A name given to the resource Structural and geochemical inter-relationships between gold and tungsten using arsenic as a proxy for gold Subject The topic of the resource Geochemistry East Otago. gold Macraes Mine scheelite tungstan