Show simple item record

dc.contributor.advisorCraw, Dave
dc.contributor.advisorMackenzie, Doug
dc.contributor.authorStephens, Samuel
dc.date.available2017-04-18T21:12:05Z
dc.date.copyright2014
dc.identifier.citationStephens, S. (2014). Characterisation of gold mineralisation and geophysical aided geological mapping in the Old Man Range, Central Otago, New Zealand (Dissertation, BAppSc. (Hons.)). University of Otago. Retrieved from http://hdl.handle.net/10523/7295en
dc.identifier.urihttp://hdl.handle.net/10523/7295
dc.description.abstractSix 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 eastwest 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 -1 m wide normal fault zones. They are discontinuous but can be traced for up to - l 50m, 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-lOlMa), 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.en_NZ
dc.format.mimetypeapplication/pdf
dc.language.isoenen_NZ
dc.publisherUniversity of Otago
dc.titleCharacterisation of gold mineralisation and geophysical aided geological mapping in the Old Man Range, Central Otago, New Zealanden_NZ
dc.typeDissertation
dc.date.updated2017-04-18T21:11:29Z
thesis.degree.disciplineApplied Geologyen_NZ
thesis.degree.nameBAppSc. (Hons.)en_NZ
thesis.degree.grantorUniversity of Otago
thesis.degree.levelHonours Dissertation
otago.openaccessOpenen_NZ
 Find in your library

Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record