Raja Yarra - Profile on Academia.edu (original) (raw)
Papers by Raja Yarra
The Kapan District located in the Syunik province of SE Armenia is part of the Lesser Caucasus. T... more The Kapan District located in the Syunik province of SE Armenia is part of the Lesser Caucasus. The district consists of multiple vein type deposits that were emplaced in the Middle-Upper Jurassic. The Shahumyan deposit is the only actively producing deposit within the district. Understanding vein geometry, and hydrothermal fluid evolution is fundamental in establishing the genesis and exploration significance within an epithermal vein district, providing both near mine and district scale targets. Over 120 veins of varying thicknesses (20cm to 3 m) are identified at the Shahumyan deposit. The veins are sub-vertical, south-dipping and trend east to northeast. Veins comprise of small bends, extensional jogs, soft and hard linked step-overs, pinch and swell structures and cymoid loops. These features are observed along both strike and down-dip of individual veins and contain higher metal grades relative to the rest of the vein. Along strike and down-dip connectivity of these structural features define high-grade ore-shoots within mineralized veins. Three main hydrothermal stages associated with mineralization are defined: Stage 1, pyrite, fine grained quartz ±chlorite; Stage 2a & b, pyrite, chalcopyrite, sphalerite, galena, sulfosalts, Au-Ag tellurides, fine and coarse white quartz, ±calcite; Stage 3; calcite, quartz, pyrite. Au-Ag-Pb tellurides are associated with localized brecciation. Tellurides are predominantly present in fractured sphalerite, pyrite, chalcopyrite and galena. Based on textures and fluid inclusion studies, Au-Ag-Pb tellurides are linked to boiling mechanisms. Preface An introduction is presented in Chapter 1, where research concepts and objectivrs are outlined. A summary and discussion of the research results, implications and suggested future work is present in Chapter 5. Chapter 2 reviews the tectonic and regional geology of the Lesser Caucasus and the Kapan Volcanic Zone in addition to economic history of the Kapan District and its exploited metals. Chapters 3 and 4 include a presentation of quantitative and qualitative data collected to answer objectives outlined in Chapter 1 in addition to data interpretation. The author is responsible for all of the structural measurements, descriptive data collected and for the selection of the following analytical samples: (1) shortwave infrared spectroscopy; (2) X-ray diffraction; (3) microprobe / SEM; (4) lithogeochemical; (5) fluid inclusion microthermometry; and (6) Ar/Ar and K/Ar geochronology. The author is responsible for the generation of all figures and tables, unless otherwise noted. Analytical methods 2-3 were undertaken at UBC by the author with assistance from Jenny Lai and Edith Czech. Methods 1 and 5 were undertaken at UBC with the assistance of Farhad Bouzari and Murray Allan.
Recognition of hydrothermal alteration using airborne hyperspectral imagery and gold favourability mapping in the Hope Bay Volcanic Belt, Nunavut
Sulfide paragenesis and alteration of the Shahumyan polymetallic vein-hosted epithermal deposit, Kapan district SE Armenia*
The Lesser Caucasus is part of the west-central Tethyan metallogenic belt, which comprises multip... more The Lesser Caucasus is part of the west-central Tethyan metallogenic belt, which comprises multiple mining districts in Georgia, Azerbaijan, and Armenia. The Amulsar low-sulphidation epithermal deposit in Armenia and Gedabek an epithermal deposit in western Azerbaijan are examples of deposits found in two separate metallogenic periods. Amulsar is associated with Paleogene volcanic and intrusive rocks, whereas Gedabek is associated with Jurassic aged volcanic and intrusive rocks. Deposits found in the Kapan district of SE Armenia are similar in age to the Gedabek district and contain three prominent metallic deposits: Barabatum, Centralni, and Shahumyan. The latter is a polymetallic (Zn-Cu-Pb-Ag-Au), vein-hosted deposit and the only actively producing deposit in the district. The mineralization is hosted by the Barabatum volcanic unit, part of the Middle Jurassic volcanic complex composed of Bajocian and Bathonian andesite and dacite lava flows and intermediate volcaniclastic rocks. ...
Geological Survey of Canada, 2014
kaolinite contains a doublet feature between 2150-2215 and 2160-2206; and montmorillonite which h... more kaolinite contains a doublet feature between 2150-2215 and 2160-2206; and montmorillonite which has an absorption feature in the same range as kaolinite however the doublet feature is absent leading to a wide absorption trough.
The Kapan District located in the Syunik province of SE Armenia is part of the Lesser Caucasus. T... more The Kapan District located in the Syunik province of SE Armenia is part of the Lesser Caucasus. The district consists of multiple vein type deposits that were emplaced in the Middle-Upper Jurassic. The Shahumyan deposit is the only actively producing deposit within the district. Understanding vein geometry, and hydrothermal fluid evolution is fundamental in establishing the genesis and exploration significance within an epithermal vein district, providing both near mine and district scale targets. Over 120 veins of varying thicknesses (20cm to 3 m) are identified at the Shahumyan deposit. The veins are sub-vertical, south-dipping and trend east to northeast. Veins comprise of small bends, extensional jogs, soft and hard linked step-overs, pinch and swell structures and cymoid loops. These features are observed along both strike and down-dip of individual veins and contain higher metal grades relative to the rest of the vein. Along strike and down-dip connectivity of these structural features define high-grade ore-shoots within mineralized veins. Three main hydrothermal stages associated with mineralization are defined: Stage 1, pyrite, fine grained quartz ±chlorite; Stage 2a & b, pyrite, chalcopyrite, sphalerite, galena, sulfosalts, Au-Ag tellurides, fine and coarse white quartz, ±calcite; Stage 3; calcite, quartz, pyrite. Au-Ag-Pb tellurides are associated with localized brecciation. Tellurides are predominantly present in fractured sphalerite, pyrite, chalcopyrite and galena. Based on textures and fluid inclusion studies, Au-Ag-Pb tellurides are linked to boiling mechanisms. Preface An introduction is presented in Chapter 1, where research concepts and objectivrs are outlined. A summary and discussion of the research results, implications and suggested future work is present in Chapter 5. Chapter 2 reviews the tectonic and regional geology of the Lesser Caucasus and the Kapan Volcanic Zone in addition to economic history of the Kapan District and its exploited metals. Chapters 3 and 4 include a presentation of quantitative and qualitative data collected to answer objectives outlined in Chapter 1 in addition to data interpretation. The author is responsible for all of the structural measurements, descriptive data collected and for the selection of the following analytical samples: (1) shortwave infrared spectroscopy; (2) X-ray diffraction; (3) microprobe / SEM; (4) lithogeochemical; (5) fluid inclusion microthermometry; and (6) Ar/Ar and K/Ar geochronology. The author is responsible for the generation of all figures and tables, unless otherwise noted. Analytical methods 2-3 were undertaken at UBC by the author with assistance from Jenny Lai and Edith Czech. Methods 1 and 5 were undertaken at UBC with the assistance of Farhad Bouzari and Murray Allan.
Recognition of hydrothermal alteration using airborne hyperspectral imagery and gold favourability mapping in the Hope Bay Volcanic Belt, Nunavut
Sulfide paragenesis and alteration of the Shahumyan polymetallic vein-hosted epithermal deposit, Kapan district SE Armenia*
The Lesser Caucasus is part of the west-central Tethyan metallogenic belt, which comprises multip... more The Lesser Caucasus is part of the west-central Tethyan metallogenic belt, which comprises multiple mining districts in Georgia, Azerbaijan, and Armenia. The Amulsar low-sulphidation epithermal deposit in Armenia and Gedabek an epithermal deposit in western Azerbaijan are examples of deposits found in two separate metallogenic periods. Amulsar is associated with Paleogene volcanic and intrusive rocks, whereas Gedabek is associated with Jurassic aged volcanic and intrusive rocks. Deposits found in the Kapan district of SE Armenia are similar in age to the Gedabek district and contain three prominent metallic deposits: Barabatum, Centralni, and Shahumyan. The latter is a polymetallic (Zn-Cu-Pb-Ag-Au), vein-hosted deposit and the only actively producing deposit in the district. The mineralization is hosted by the Barabatum volcanic unit, part of the Middle Jurassic volcanic complex composed of Bajocian and Bathonian andesite and dacite lava flows and intermediate volcaniclastic rocks. ...
Geological Survey of Canada, 2014
kaolinite contains a doublet feature between 2150-2215 and 2160-2206; and montmorillonite which h... more kaolinite contains a doublet feature between 2150-2215 and 2160-2206; and montmorillonite which has an absorption feature in the same range as kaolinite however the doublet feature is absent leading to a wide absorption trough.