title: Identifying Mineralogical and Geochemical Vectors towards the Epithermal Au-Ag Correnso Mine, Waihi

authors: Singh, Ravinder Sardul

subjects: Correnso Deposit

abstract: The Au-Ag rich Correnso vein is a low sulphidation epithermal deposit located east of Waihi and is named after the clay mineral corrensite. Hydrothermally altered andesitic and dacitic host rocks of the Waipupu Formation, informally subdivided into Upper Andesite and Lower Andesite units, contain Au-Ag rich quartz veins. The interaction of hot, dominantly meteoric water with the host rocks causes mineralogical and geochemical changes. Hydrothermal alteration manifested as mineralogical alteration and geochemical signatures can help in identifying vectors to constrain potential areas of enhanced mineralization for exploration purposes. Hydrothermal alteration has been suggested to have potential as exploration vector for epithermal deposits in particular as alteration halos can extend up to considerable distances (Christie et al., 2001; Simpson and Mauk, 2004). 
Visual core logging, petrography, pXRF, and Aqua-Regia/2-Acid Digest (ICP-MS) analysis were used in this study to analyse and quantify alteration zonation patterns and trace element metasomatism in order to identify vectors towards the mineralisation. Results suggest a clear mineralogical and geochemical alteration zonation pattern around the vein system. The unaltered, moderately altered and highly altered rocks are often adjacent to one another, implying that hydrothermal fluids have migrated through the host rocks in a highly heterogeneous fashion. The migration of fluids is likely controlled by both primary and secondary (e.g. fault/fracture) permeability. The overall mineralogical pattern can be described as quartz ± adularia ± sericite assemblage which is similar to the adjacent deposits of the Waihi area. Alteration zonation in the host rocks consists of potassic alteration proximal to the vein system surrounded by sericitic alteration, with illite-smectite dominated argillic assemblage overprinting both alteration types. Propylitic alteration is more prominent to the outward zones and distal to the mineralisation. Geochemical analysis show enrichment of pathfinder elements such as As, As, Sb, Hg, Zn, Pb, Se, and K and depletion of Cu, Te and Se.

text: Identifying Mineralogical and Geochemical Vectors towards the Epithermal Au-Ag Correnso Mine, Waihi The Au-Ag rich Correnso vein is a low sulphidation epithermal deposit located east of Waihi and is named after the clay mineral corrensite. Hydrothermally altered andesitic and dacitic host rocks of the Waipupu Formation, informally subdivided into Upper Andesite and Lower Andesite units, contain Au-Ag rich quartz veins. The interaction of hot, dominantly meteoric water with the host rocks causes mineralogical and geochemical changes. Hydrothermal alteration manifested as mineralogical alteration and geochemical signatures can help in identifying vectors to constrain potential areas of enhanced mineralization for exploration purposes. Hydrothermal alteration has been suggested to have potential as exploration vector for epithermal deposits in particular as alteration halos can extend up to considerable distances (Christie et al., 2001; Simpson and Mauk, 2004). 
Visual core logging, petrography, pXRF, and Aqua-Regia/2-Acid Digest (ICP-MS) analysis were used in this study to analyse and quantify alteration zonation patterns and trace element metasomatism in order to identify vectors towards the mineralisation. Results suggest a clear mineralogical and geochemical alteration zonation pattern around the vein system. The unaltered, moderately altered and highly altered rocks are often adjacent to one another, implying that hydrothermal fluids have migrated through the host rocks in a highly heterogeneous fashion. The migration of fluids is likely controlled by both primary and secondary (e.g. fault/fracture) permeability. The overall mineralogical pattern can be described as quartz ± adularia ± sericite assemblage which is similar to the adjacent deposits of the Waihi area. Alteration zonation in the host rocks consists of potassic alteration proximal to the vein system surrounded by sericitic alteration, with illite-smectite dominated argillic assemblage overprinting both alteration types. Propylitic alteration is more prominent to the outward zones and distal to the mineralisation. Geochemical analysis show enrichment of pathfinder elements such as As, As, Sb, Hg, Zn, Pb, Se, and K and depletion of Cu, Te and Se.

year: 2015

title: Development and characterisation of an easily configurable range imaging system

authors: Jongenelen, Adrian P.P.

subjects: range imaging

abstract: Range imaging is becoming a popular tool for many applications, with several commercial variants now available. These systems find numerous real world applications such as interactive gaming and the automotive industry. This paper describes the development of a range imaging system employing the PMD-19 k sensor from PMD technologies. One specific advantage of our system is that it is extremely customisable in terms of modulation patterns to act as a platform for further research into time-of-flight range imaging. Experimental results are presented giving an indication of the precision and accuracy of the system, and how modifying certain operating parameters can improve system performance.

text: Development and characterisation of an easily configurable range imaging system Range imaging is becoming a popular tool for many applications, with several commercial variants now available. These systems find numerous real world applications such as interactive gaming and the automotive industry. This paper describes the development of a range imaging system employing the PMD-19 k sensor from PMD technologies. One specific advantage of our system is that it is extremely customisable in terms of modulation patterns to act as a platform for further research into time-of-flight range imaging. Experimental results are presented giving an indication of the precision and accuracy of the system, and how modifying certain operating parameters can improve system performance.

year: 2009

title: Reducing our prison population: Past failures and new approaches

authors: Tauri, Juan Marcellus

abstract: Earlier this year the Minister of Justice, Andrew Little announced the latest in a long line of reviews, taxpayer-funded summits and inter-agency, ‘wholeof-government’ projects stretching back to the late-1980s, all aimed in some form or other, at making the criminal justice system more ‘safe’ and ‘effective’. Officially launched at a summit held in Porirua in August 2018, the aim of the latest review is to reduce New Zealand’s prison muster by 30% over the next 15 years. And unsurprisingly, given our significant over-representation in prisons, a specific focus of the review is on identifying ways to significantly reduce Māori over-representation in the prison population. This commentary represents a modest offering in response to the current government’s stated aim of making the justice system safer and more effective, and to reduce the prison muster, and it is based on two core arguments, namely that successive governments and the public service have failed to reduce offending and imprisonment and that successful solutions require community empowerment and government/public service accountability.

text: Reducing our prison population: Past failures and new approaches Earlier this year the Minister of Justice, Andrew Little announced the latest in a long line of reviews, taxpayer-funded summits and inter-agency, ‘wholeof-government’ projects stretching back to the late-1980s, all aimed in some form or other, at making the criminal justice system more ‘safe’ and ‘effective’. Officially launched at a summit held in Porirua in August 2018, the aim of the latest review is to reduce New Zealand’s prison muster by 30% over the next 15 years. And unsurprisingly, given our significant over-representation in prisons, a specific focus of the review is on identifying ways to significantly reduce Māori over-representation in the prison population. This commentary represents a modest offering in response to the current government’s stated aim of making the justice system safer and more effective, and to reduce the prison muster, and it is based on two core arguments, namely that successive governments and the public service have failed to reduce offending and imprisonment and that successful solutions require community empowerment and government/public service accountability.

year: 2019