Гидротермальные изменения, выявленные с помощью люминесценции и химического состава апатита: потенциальный минерал-индикатор для изучения скрытых порфирово-медных месторождений

Apatite is a common resistate mineral occurring in a range of host rocks and ore-related hydrothermal alteration assemblages. Apatite in several porphyry copper deposits in British Columbia has a unique set of physical and compositional characteristics that can be used to evaluate the chemical conditions of magmas that formed the causative intrusions or associated hydrothermal alteration.

The Cadia Ridgeway deposit is one of a group of porphyry-style deposits discovered since 1992 by Newcrest geologists at Cadia 20 kms south of Orange in the central tablelands of New South Wales, Australia. The Ridgeway deposit lies 500m below the surface, 3 kms north-west of the Cadia Hill open cut mine, and was discovered in November 1996. It is notably rich in Au with an inferred and indicated resource of 44 Mt at 2.6 g/t Au and 0.82% Cu, and is under development as an underground mining operation. <...>

Extensive research during the 20th century on porphyry Cu (-Mo-Au) deposits has revealed the following major geodynamic, petrological, mineralogical, and geochemical features that characterize these deposits: (1) these systems commonly occur in continental and oceanic magmatic arcs or in collisional orogenic belts; (2) they have spatial and genetic relationships to basaltic-to-felsic magmas emplaced in the upper 10 km of the crust;

Porphyry deposits are the world's most important source of Cu and Mo, and are major sources of Au, Ag, and Sn; significant byproduct metals include Re, W, In, Pt, Pd, and Se. They account for about 50 to 60% of world Cu production and more than 95% of world Mo production. In Canada, they account for more than 40% of Cu production, virtually all Mo production, and about 10% of Au production. Porphyry deposits are large, low- to medium-grade deposits in which primary (hypogene) ore minerals are dominantly structurally controlled and which are spatially and genetically related to felsic to intermediate porphyritic intrusions.

В последнее десятилетие в мире произошло резкое снижение новых открытий рудных месторождений, связанное как с уменьшением расходов на ГРР (рис. 1), так и с перемещением поисков на большие глубины, как правило скрытых объектов.

В металлогенических поясах Северо-Востока России, рассматриваемых в настоящей статье, по аналогии с другими регионами Тихоокеанского кольца, весьма реальны перспективы открытия крупных и сверхкрупных Au-Cu-Mo-порфировых и Au-Ag-эпитермальных месторождений. Интрузивно-купольные структуры вулканических поясов среднепалеозойского, позднеюрско-раннемелового и позднемелового возраста контролируют размещение этих месторождений. В статье приведены новые данные, позволяющие судить об условиях формирования и источниках вещества месторождений Баимского и Кони-Пъягинского рудных районов, Олойского и Удско-Мургальского металлогенических поясов. Обсуждается ряд аспектов геолого-генетической модели медно-порфировой рудно-магматической системы.

A single mining camp or ore deposit can contain multiple mineral deposit types but may have mineral reserves or resources classified by what a mining or mineral exploration company considers to be the dominant mineralization type in the area. In this paper, we summarize recent work on the challenges of reporting mineral deposits by geologic processes rather than by grades, tonnages, and mineral processing approaches. For example, the Ertsberg-Grasberg district of Indonesia contains several large skarn Cu-Au-Ag deposits, with the discovery outcrop as well as early production entirely in skarn.

Ordovician volcanic, volcaniclastic and intrusive rocks of calc-alkaline affinity in the Eastern Subprovince of the Lachlan Orogen were formed in the intraoceanic Macquarie Volcanic Arc. The Macquarie Arc was developed in response to west-dipping subduction along part of the boundary between eastern Gondwana and the proto-Pacific Plate and was situated on the Gondwana Plate, some 1000 km east of Precambrian continental crust. The intervening area was occupied by a back arc basin that developed on oceanic crust as the proto-PacificPlate rolled back eastwards after the Middle Cambrian Delamerian Orogeny. Subsequent extension, strike-slip translation and thin-skinned tectonics have structurally dissected the single arc into four north to NNE trending structural belts of Ordovician calc-alkaline rocks that are separated largely by younger rift basins and in part by coeval craton-derived turbidites.

Abstract - Hydrothermal copper & gold deposits associated with felsic intrusives, particularly porphyry related and epithermal ores, are found in a series of extensive, narrow, linear metallogenic provinces throughout the world. These are predominantly associated with the great Mesozoic to Cainozoic orogenic belts. Major deposits however, are also found within Palaeozoic orogens, while a few are known from the Precambrian. The style and setting of these deposits is variable and diverse, although many common features emerge from a global comparison.

Analyses of exploration and mining case studies as well as magmatic arc geothermal systems have facilitated an understanding of the implications to explorationists of the anatomy of porphyry related Au-Cu-Mo-Ag mineralising systems. Deeply eroded magmatic source rocks tend to host sub economic mineralisation, which may become focused in the highly prospective in overlying apophyses to spine-like polyphasal intrusions. Buried targets may be identified by analyses of zoned alteration and mineralisation developed by complex overprinting relationships. Mineralised fluids may exit from the magmatic source migrating to higher crustal levels to form epithermal deposits. High sulphidation epithermal Au + Cu + Ag deposits display characteristic alteration and mineralisation zonation which aids target generation and in some instances evolve to host marginal and overprinting lower sulphidation ores which display improved metallurgy and metal grades. Low sulphidation epithermal Au-Ag deposits are categorised as a number of styles, linked on an overall anatomy, which display considerable variation in metal grade, size, form and metallurgy, typically governed by setting and crustal level of formation, as well as controls to vein formation such as: host rock competency, structure, and mechanism of Au deposition. All these controls and zonation pattern vectors provide valuable tools to explorationists in the search for hidden ores.