Добрый день, Коллеги. Важное сообщение, просьба принять участие. Музей Ферсмана ищет помощь для реставрационных работ в помещении. Подробности по ссылке
Sediment-hosted disseminated gold deposits in NW Sichuan China have many features in common with the well-known Carlin-type deposits in the western United States. They are hosted by Middle–Upper Triassic turbidites composed of 1300–4300 m of rhythmically interbedded, slightly metamorphosed calcareous sandstone, siltstone, and slate. The ore bodies are typically layer- or lens-like in shape and generally extend parallel to the stratification of the host sedimentary rocks, with a strike length of tens to several hundreds of meters. The immediate host rocks consist mainly of calcareous slate and siltstone characterized by high contents of organic matter and diagenetic pyrite. The main primary ore minerals associated with gold mineralization include pyrite, arsenopyrite, realgar, and stibnite. Gangue minerals comprise mostly quartz, calcite and dolomite. Gold is extremely fine-grained, usually less than 1 Am, and cannot be seen with an electron microscope.
The paper records the first occurrence of dolomite-hosted, disseminated gold mineralization at Barhi and Jhal, in a Late Archean-Early Proterozoic metavolcano-sedimentary belt ŽMahakoshal fold belt. in central India. Gold mineralization is hosted by dolomite that occurs as discontinuous bands interbedded with phyllite. Hydrothermal alteration styles of the host rock include decalcification, silicification, and argillization. Pyrite is the most common sulfide, whereas stibnite and realgar are rare. Mineralization is characterized by persistent gold from 0.20 to 0.62 ppm and a consistent association of anomalous arsenic, antimony, and mercury with gold.
Книга написана группой авторов, имеющих самое непосредственное отношение к проблемам золота и драгоценных камней. В первую очередь будет полезна ювелирам-профессионалам, банкирам, банковским работникам, менеджерам, поставщикам золотого лома и неограненных алмазов.
В книге приведены новые сведения, о которых ранее не всегда могли знать даже специалисты. Известно, что во времена социализма все то, что было связано с золотом и алмазами, носило достаточно секретный характер или предназначалось для служебного пользования. Теперь представилась возможность рассказать об этом. Тем не менее, авторы не претендуют на полные, энциклопедические знания в этой области, однако то, о чем читатель прочтет в книге, достоверно.
Книга производит впечатление бестселлера, особенно для молодежи.
Издание предполагается как пробное. В нем использованы справочные и другие материалы из латвийских и зарубежных изданий.
Постаккреционная металлогения Восточной Якутии характеризуется доминирующим развитием эпитермальной Au-Hg минерализации (Суплецов, 2001). Конформные металлогенические зоны золотоносного Hg оруденения, контролируемые продольными разломами, расположены в структурах Колымо-Омолонского микроконтинента и Верхоянского складчатого пояса. Данные разломы, как правило, трассируются свитами кайнотипных даек щелочных базальтоидов. Металлогенические построения позволили выделить две генетически близкие группы Au-Hg месторождений, локализованные в карбонатных и терригенных комплексах пород, отличающихся морфоструктурой, гидротермальными изменениями и масштабами оруденения. Ртути и сурьме в данных месторождениях, скорее всего, принадлежит второстепенное значение, и они выступают в качестве бипродукта.
Приведены сведения о современном состоянии отечественной золотодобывающей промышленности и ее проблемах. Изложены методы оптимизации параметров эксплуатационной разведки. Рассмотрены технологические схемы ведения добычных работ открытым и подземным способами. Уделено внимание технологаи повторной разработки остаточных запасов подземных рудников открытым способом. Описаны методы взрывной отбойки пород, а также методы управления сдвижением массива горных пород и горным давлением.
Для инженерно-технических работников золотодобывающей промышленности.
In 1997 the British Columbia Geological Survey (BCGS) initiated a project to identify prospective areas for sediment-hosted gold mineralization. The inspiration for the project came from presentations and articles by Howard Poulsen of the Geological Survey of Canada (1996a, 1996b). He pointed out that there is potential to find hypogene, sediment-hosted gold mineralization in Canada akin to deposits found in Nevada. He mentioned that if an intrusive association is important to generate the mineralization, then two different geological environments might host this style of mineralization. Accreted terranes with a basement containing carbonate lithologies intruded by Mesozoic or Cenozic plutonism would be a prospective geological setting, specifically the Stikine and Quesnel terranes. The second favourable environment is within the sediments deposited along the continental margin of ancestral North America which have been cut by Mesozoic magmas, such as are found in the Kootenay Arc and Selwyn Basin (Figure 1).
Others have considered British Columbia as prospective territory for sediment-hosted gold. Early work by companies focused on the Insular Belt rocks exposed on Vancouver Island and the Queen Charlottes. These exploration programs were based largely on an epithermal-style model for the mineralization which was in favour at the time. The discovery of the Babe deposit (now called the Specogna or Cinola) in the Queen Charlotte Islands in 1970 increased the interest in this model because it was initially identified as a Carlin-type deposit (Richards et al, 1976; Champigny and Sinclair, 1982). <...>
The Carlin trend contains the largest concentration of Carlin-type gold deposits in the world. Two major controversies about these giant gold deposits have been their age, which is now firmly established as Eocene, and the source of heat, fluids, and metals, which remains debated. We present data that demonstrate an intense period of Eocene magmatism coincided in time and space with deposit formation and was arguably the primary heat source. Geologic studies over the last 40 years have emphasized the stratigraphy and structure of Paleozoic sedimentary rocks, which are the major ore hosts. However, four igneous episodes affected the Carlin trend, in the Jurassic, Cretaceous, Eocene, and Miocene. A Jurassic diorite-granodiorite laccolith and related dikes were emplaced at about 158 Ma in the northern Carlin trend. A Cretaceous granite intruded the northcentral part of the trend at 112 Ma. Abundant Eocene dikes intruded along most of the trend and were accompanied by lavas in a large volcanic field along the southwest edge of the trend between ~40 and 36 Ma. Miocene rhyolite lavas erupted just west of and across the southern part of the trend at ~15 Ma.
Gold occurs as primary commodity in a wide range of gold deposit types and settings. In the last decade, significant progress has been made in the classification, definition and understanding of the main gold deposit types. Three main clans of deposits are now broadly defined, each including a range of specific deposit types with common characteristics and tectonic settings. The orogenic clan has been introduced to include vein-type deposits formed during crustal shortening of their host greenstone, BIF or clastic sedimentary rock sequences. Deposits of the new reduced intrusion-related clan share an Au-Bi-Te-As metal signature and an association with moderately reduced equigranular post-orogenic granitic intrusions. Oxidized intrusion-related deposits, including porphyry, skarn, and high-sulfidation epithermal deposits, are associated with high-level, oxidized porphyry stocks in magmatic arcs. Other important deposit types include Carlin, low-sulfidation epithermal, Au-rich VMS and Witwatersrand deposits. The key geology features of the ore-forming environments and the key geologic manifestations of the different deposit types form the footprints of ore systems that are targeted in exploration programs. Important progress has been made in our ability to integrate, process, and visualize increasingly complex datasets in 2D GIS and 3D platforms. For gold exploration, important geophysical advances include airborne gravity, routine 3D inversions of potential field data, and 3D modeling of electrical data. Improved satellite-, airborne- and field-based infrared spectroscopy has significantly improved alteration mapping around gold systems, extending the dimensions of the footprints and enhancing vectoring capabilities. Conventional geochemistry remains very important to gold exploration, while promising new techniques are being tested. Selection of the appropriate exploration methods must be dictated by the characteristics of the targeted model, its geologic setting, and the surficial environment. Both greenfield and brownfield exploration contributed to the discovery of major gold deposits (>2.5 moz Au) in the last decade but the discovery rates have declined significantly. Geologists are now better equipped than ever to face this difficult challenge, but geological understanding and quality field work were important discovery factors and must remain the key underpinnings of exploration programs.
Монография посвящена детальному описанию золоторудного месторождения мирового класса, расположенного на площади Яно-Колымской складчатой системы. Рассмотрена региональная тектоническая позиция рудного района. Приведены данные по геологическому строению рудно-россыпного узла и его главного объекта -Наталкинского месторождения. Охарактеризованы аккумулятивные и интрузивные комплексы, минералогия и геохимия рудных зон, их строение с акцентом на выявление закономерностей размещения благороднометалльной минерализации. Сделан предварительный вывод о комплексном золото-платина-палладиевом типе оруденения на месторождении. На основе минералого-геохимических и термобарогеохимических данных рассмотрены особенности генезиса, в том числе регенерации и реювенации оруденения. Выполнен анализ россыпной золотоносности рудного узла с использованием сведений по типоморфизму рудного и россыпного золота. Разработана геолого-геохимическая модель рудного узла.
