New Zealand Journal of Geology and Geophysics, Oct 1, 1987
Abstract Tarpaulin Metagranite (new name), a deformed, two-mica granitoid, crops out on The Neck,... more Abstract Tarpaulin Metagranite (new name), a deformed, two-mica granitoid, crops out on The Neck, northeastern Stewart Island. It lies in fault contact with the Anglern Complex to the north, and the Paterson Group to the south.
New Zealand Journal of Geology and Geophysics, Sep 1, 1992
Park Volcanics Group is proposed for igneous rocks, either shallow intrusive or extrusive, emplac... more Park Volcanics Group is proposed for igneous rocks, either shallow intrusive or extrusive, emplaced in the Murihiku Terrane during Triassic‐Jurassic times. The term replaces Park Intrusives of Mutch, some members of which are shown to be extrusive rather than intrusive. Formation status within the group is given to Gowan Andesite and Pinney Volcanics (new names) in western Southland, Glenham Porphyry
New Zealand Journal of Geology and Geophysics, Dec 1, 1996
The Late Triassic to Early Jurassic Park Volcanics Group comprises minor shallow intrusive and ex... more The Late Triassic to Early Jurassic Park Volcanics Group comprises minor shallow intrusive and extrusive bodies emplaced during mainly marine sedimentation of the Murihiku Terrane, southern New Zealand. Gowan Andesite in western Southland and Glenham Porphyry andesites in eastern Southland are high‐K andesites. Glassy examples have commonly lost K during alteration. Orthoclase contents of Or3.6–3.7 in plagioclase phenocrysts at An50
This guidebook on the gold and magmatic Cu-Ni-PGE deposits of Lapland highlights deposit characte... more This guidebook on the gold and magmatic Cu-Ni-PGE deposits of Lapland highlights deposit characteristics, their diversity, and temporal and spatial relationships. The tectonic setting and relationship to the general geodynamic evolution of the Fennoscandian Shield are examined as well. In addition, deposit-scale controls and structural features are considered to understand the ore genesis. Areas covered include the Portimo Layered Complex, Kevitsa intrusion, Pahtavaara gold mine, Sakatti deposit, Risti and Launi gold projects, Mustajärvi orogenic gold occurrence, Suurikuusikko gold deposit (Kittilä mine), and Rjapalot gold-cobalt project.
Bulletin of the Geological Society of Finland, 2021
SEM-based automated mineralogy (SEM-AM) techniques allow fast and effective way of studying the t... more SEM-based automated mineralogy (SEM-AM) techniques allow fast and effective way of studying the textural settings of gold in hydrothermal deposits. Unsupervised machine learning (e.g. self-organizing maps) is an intuitive way of processing multi-dimensional geochemical datasets in order to reveal hidden patterns potentially represent different mineralization stages. We combined these two methods for studying the relationship of gold and cobalt within different prospects in a Paleoproterozoic gold-cobalt mineralized area known as Rajapalot. Gold is found as a texturally late phase, occurring in fractures of silicates and sulfides. Based on the elemental associations observed from the whole-rock geochemical dataset using self-organizing-maps, Co-only, Au-Co and Au associations can be inferred relating to either different mineralization stages or different fluid-host rock interactions. Also, the dominant mineralization-related alteration in different occurrences within the Rajapalot Au...
Abstract The Raja Au-Co mineralization in the Paleoproterozoic Peräpohja belt in northern Finland... more Abstract The Raja Au-Co mineralization in the Paleoproterozoic Peräpohja belt in northern Finland is part of the wider Rompas-Rajapalot mineralized area with several known Au-Co occurrences. The area is characterized by distinct tourmaline occurrences, spatially associated with Au-Co mineralization. Four texturally distinct tourmaline types were identified although all analysed tourmalines belong to the alkali-group and are classified as dravite. δ ¹¹B values and fractionation modelling indicates that at least two distinct fluids were responsible for the tourmaline formation with initial end member δ¹¹B values of the fluids at −8‰ and −1‰. Possible sources for boron rich fluids are Svecofennian orogeny related (ca. < 1.9 Ga) metamorphic fluids and magmatic-hydrothermal fluids related to the late-orogenic ca. 1.78 Ga granitoids. Structural data from the quartz-tourmaline veins outlines a strong linear trend towards the Raja high-grade mineralization trend. This is interpreted as evidence for structural control of the Raja mineralization, which possibly is contained in shear-zones or within the hinge regions of local high degree folding. A distinctive rock unit with bright purple anhydrite layers and white gypsum veins has been intersected by drilling. While the sulfate-rich unit is unmineralized, the mineralogy and regional geological setting suggests an evaporitic origin. Anhydrite has δ³⁴S values in a narrow range from 8.1 to 9.8 ‰. Gypsum has slightly heavier δ³⁴S from 10.6 to 12.2 ‰. Together with isotope fractionation constraints, textural evidence suggests the authigenic formation of gypsum with SO₄²⁻ sourced from anhydrite. Significant similarities in textures and sulfur isotope values to well-known evaporite successions of the Onega basin, western Russia, further supports the presence of evaporitic strata within the Peräpohja belt
New Zealand Journal of Geology and Geophysics, Oct 1, 1987
Abstract Tarpaulin Metagranite (new name), a deformed, two-mica granitoid, crops out on The Neck,... more Abstract Tarpaulin Metagranite (new name), a deformed, two-mica granitoid, crops out on The Neck, northeastern Stewart Island. It lies in fault contact with the Anglern Complex to the north, and the Paterson Group to the south.
New Zealand Journal of Geology and Geophysics, Sep 1, 1992
Park Volcanics Group is proposed for igneous rocks, either shallow intrusive or extrusive, emplac... more Park Volcanics Group is proposed for igneous rocks, either shallow intrusive or extrusive, emplaced in the Murihiku Terrane during Triassic‐Jurassic times. The term replaces Park Intrusives of Mutch, some members of which are shown to be extrusive rather than intrusive. Formation status within the group is given to Gowan Andesite and Pinney Volcanics (new names) in western Southland, Glenham Porphyry
New Zealand Journal of Geology and Geophysics, Dec 1, 1996
The Late Triassic to Early Jurassic Park Volcanics Group comprises minor shallow intrusive and ex... more The Late Triassic to Early Jurassic Park Volcanics Group comprises minor shallow intrusive and extrusive bodies emplaced during mainly marine sedimentation of the Murihiku Terrane, southern New Zealand. Gowan Andesite in western Southland and Glenham Porphyry andesites in eastern Southland are high‐K andesites. Glassy examples have commonly lost K during alteration. Orthoclase contents of Or3.6–3.7 in plagioclase phenocrysts at An50
This guidebook on the gold and magmatic Cu-Ni-PGE deposits of Lapland highlights deposit characte... more This guidebook on the gold and magmatic Cu-Ni-PGE deposits of Lapland highlights deposit characteristics, their diversity, and temporal and spatial relationships. The tectonic setting and relationship to the general geodynamic evolution of the Fennoscandian Shield are examined as well. In addition, deposit-scale controls and structural features are considered to understand the ore genesis. Areas covered include the Portimo Layered Complex, Kevitsa intrusion, Pahtavaara gold mine, Sakatti deposit, Risti and Launi gold projects, Mustajärvi orogenic gold occurrence, Suurikuusikko gold deposit (Kittilä mine), and Rjapalot gold-cobalt project.
Bulletin of the Geological Society of Finland, 2021
SEM-based automated mineralogy (SEM-AM) techniques allow fast and effective way of studying the t... more SEM-based automated mineralogy (SEM-AM) techniques allow fast and effective way of studying the textural settings of gold in hydrothermal deposits. Unsupervised machine learning (e.g. self-organizing maps) is an intuitive way of processing multi-dimensional geochemical datasets in order to reveal hidden patterns potentially represent different mineralization stages. We combined these two methods for studying the relationship of gold and cobalt within different prospects in a Paleoproterozoic gold-cobalt mineralized area known as Rajapalot. Gold is found as a texturally late phase, occurring in fractures of silicates and sulfides. Based on the elemental associations observed from the whole-rock geochemical dataset using self-organizing-maps, Co-only, Au-Co and Au associations can be inferred relating to either different mineralization stages or different fluid-host rock interactions. Also, the dominant mineralization-related alteration in different occurrences within the Rajapalot Au...
Abstract The Raja Au-Co mineralization in the Paleoproterozoic Peräpohja belt in northern Finland... more Abstract The Raja Au-Co mineralization in the Paleoproterozoic Peräpohja belt in northern Finland is part of the wider Rompas-Rajapalot mineralized area with several known Au-Co occurrences. The area is characterized by distinct tourmaline occurrences, spatially associated with Au-Co mineralization. Four texturally distinct tourmaline types were identified although all analysed tourmalines belong to the alkali-group and are classified as dravite. δ ¹¹B values and fractionation modelling indicates that at least two distinct fluids were responsible for the tourmaline formation with initial end member δ¹¹B values of the fluids at −8‰ and −1‰. Possible sources for boron rich fluids are Svecofennian orogeny related (ca. < 1.9 Ga) metamorphic fluids and magmatic-hydrothermal fluids related to the late-orogenic ca. 1.78 Ga granitoids. Structural data from the quartz-tourmaline veins outlines a strong linear trend towards the Raja high-grade mineralization trend. This is interpreted as evidence for structural control of the Raja mineralization, which possibly is contained in shear-zones or within the hinge regions of local high degree folding. A distinctive rock unit with bright purple anhydrite layers and white gypsum veins has been intersected by drilling. While the sulfate-rich unit is unmineralized, the mineralogy and regional geological setting suggests an evaporitic origin. Anhydrite has δ³⁴S values in a narrow range from 8.1 to 9.8 ‰. Gypsum has slightly heavier δ³⁴S from 10.6 to 12.2 ‰. Together with isotope fractionation constraints, textural evidence suggests the authigenic formation of gypsum with SO₄²⁻ sourced from anhydrite. Significant similarities in textures and sulfur isotope values to well-known evaporite successions of the Onega basin, western Russia, further supports the presence of evaporitic strata within the Peräpohja belt
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