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Simplified definition Quartz and carbonate veins with valuable amounts of gold and silver, in faults and shear zones located within deformed terrains of ancient to recent orogenic reenstone belts. Scientific definition Greenstone-hosted quartz-carbonate vein deposits (GQC) are a sub-type of lode gold deposits (Poulsen et al., 2000) (Fig. 1). They are also known as mesothermal, orogenic (mesozonal and hypozonal - the near surface orogenic epizonal Au-Sb-Hg deposits (Groves et al., 1998) are not included in this synthesis), lode gold, shear-zone-related quartz-carbonate or gold-only deposits (Roberts, 1987; Colvine, 1989; Kerrich and Wyman, 1990; Robert, 1990; Kerrich and Feng, 1992; Hodgson, 1993, Kerrich and Cassidy, 1994; Robert, 1995; Groves et al., 1998; Hagemann and Cassidy, 2000; Kerrich et al., 2000; Goldfarb et al., 2001; Groves et al., 2003; Goldfarb et al., in press; and references therein).
Epithermal ore deposits form at shallow depth. This conclusion was initially based on geologic reconstructions, ore mineralogy and related textures (Lindgren, 1933). It has subsequently been refined withfluid inclusion data to indicate that epithermal ores form over the temperature range of <150o C to ~300o C, from the surface to as deep as 1 to 2 km. Here we highlight the general characteristics of the two principal styles of epithermal mineralization in which gold is the dominant economic metal. We base our generalizations on observations of many deposits and prospects in the circum-Pacific region. Distinguishing between the two styles is crucial for effective exploration. Although they show similar alteration mineralogies, the distribution of the alteration zones is different, and the economic mineralization is associated with different parts of the system. The alteration zoning can be used as a pointer towards the most prospective part of the system, but only when the style has been correctly recognized. In addition, the two styles of mineralization have differences in their geochemical associations. <...>
Приводятся данные по геологии Оленинского золоторудного месторождения в зеле-нокаменном поясе Колмозеро-Воронья (Кольский полуостров), результаты геохимических и минералогических исследований его руд и рудовмещающих пород. Показана пространст-венная и генетическая связь оруденения с силлами гранит-порфиров, которые относятся к комплексу малых интрузий габбродиорит–диорит–гранодиорит-порфиров. Рассматриваются особенности околорудного изменения вмещающих пород – амфиболитов и гранит-порфиров: развитие диопсидовых, биотитовых, альбит-мусковит-кварцевых, турмалин-арсенопирит-кварцевых и собственно кварцевых метасоматитов.
Актуальность условий формирования золоторудных месторождений определяется двумя глобальными факторами. При сохранении традиционной инвестиционной привлекательности золота отмечается снижение динамики мирового производства этого драгоценного металла по фактическому объему добычи в период с 2019-2021 гг. По экспертным оценкам мировое производство золота может сократится на 15-20% уже к 2030 году по причине снижения качества и количества мировых запасов. Российский сектор будет подчиняться глобальным тенденциям, что создает возможность прохождения пиковых объемов добычи золота в нашей стране в ближайшей перспективе. Истощение сырьевой базы лидирующих золотодобывающих регионов России делает актуальным проведение геологоразведочных работ на выявление перспективных золоторудных объектов, не являющихся привычными по геологической и/или технологической характеристикам, в том числе находящихся в труднодоступных районах.
This report summarizes the primary characteristics of alkalic-type epithermal gold (Au) deposits and provides an updated descriptive model. These deposits, primarily of Mesozoic to Neogene age, are among the largest epithermal gold deposits in the world. Considered a subset of low-sulfidation epithermal deposits, they are spatially and genetically linked to small stocks or clusters of intrusions containing high alkali-element contents. Deposits occur as disseminations, breccia-fillings, and veins and may be spatially and genetically related to skarns and low-grade porphyry copper (Cu) or molybdenum (Mo) systems. Gold commonly occurs as native gold, precious metal tellurides, and as sub-micron gold in arsenian pyrite. Quartz, carbonate, fluorite, adularia, and vanadian muscovite/roscoelite are the most common gangue minerals. Alkalic-type gold deposits form in a variety of geological settings including continent-arc collision zones and back-arc or post-subduction rifts that are invariably characterized by a transition from convergent to extensional or transpressive tectonics.
Epithermal ore deposits form at shallow depth. This conclusion was initially based on geologic reconstructions, ore mineralogy and related textures (Lindgren, 1933). It has subsequently been refined withfluid inclusion data to indicate that epithermal ores form over the temperature range of <150o C to ~300o C, from the surface to as deep as 1 to 2 km. Here we highlight the general characteristics of the two principal styles of epithermal mineralization in which gold is the dominant economic metal. We base our generalizations on observations of many deposits and prospects in the circum-Pacific region. Distinguishing between the two styles is crucial for effective exploration. Although they show similar alteration mineralogies, the distribution of the alteration zones is different, and the economic mineralization is associated with different parts of the system. The alteration zoning can be used as a pointer towards the most prospective part of the system, but only when the style has been correctly recognized. In addition, the two styles of mineralization have differences in their geochemical associations. <...>
