Jan 10, 2017 economic geology sedimentary ore deposits 1. In addition, sphalerite from the center near to bottom part of the no. Some sediment hosted ore deposits were formed at various stages of basin history and are multistage. Ore is hosted by pyritic quartzpebble conglomerates formed from intense weathering of an archean granite source rock 1.
The database can be most conveniently read in filemaker pro. The objective of this report is to use both descriptive information and conceptual models to identify processes critical to the formation of sedex deposits. Geology and ore deposits of the jackrabbit area, pinal county. The mechanism of formation was first extensively studied in outcrops along the mississippi river in missouri and for this reason, they are commonly referred to as mississippi valleytype leadzinc ore deposits mvt ores. The resulting ore bodies may be stratabound and either massive or disseminated. The deposit models are presented here as a pdf file. Sources of ore forming material for pbzn deposits in the sichuanyunnanguizhou triangle area. Pdf geochemistry of sedimentary ore deposits barry. Vms, mvt, and sedex deposit types have been the source of the majority of the worlds lead and zinc. Iron ore deposits iron ore deposits are known to occur in sedimentary, hydrothermal, and magmatic environments, but production today is almost entirely from three types of deposit.
Ore deposits of lead, zinc, copper and uranium are found in continental or marine sediments. They are found mostly in sedimentary rocks, particularly limestone, shale, and sandstone. Article radiogenic pb enrichment of mississippi valley. Sedimentary ore deposits sedimentary uranium deposits. Sedimentary ore deposits the processes of sedimentation include physical, chemical and biological components. Polymictic sedimentary conglomerate overlying rhythmically laminated highgrade sphalerite and galena ore from the i 34 horizon in mcarthur river hyc deposit, australia. Sedimentary rockhosted disseminated au deposits in other parts of the world exhibit many similarities to nevada carlintype au deposits, yet no district has been discovered anywhere else that approaches nevadas au productivity. Industrial mineral deposits due to chemical sedimentation include salt and potash.
By far the most important metal from an economic and technical point of view is iron. First edition, of 1,200 copies, printed by the pioneer printing and stationery company, cheyenne. Sedimentary exhalative sedex zincleadsilver deposit model. Ores formed by sedimentary processes at the earths surface a hydrothermal fluid a hot, aqueous fluid containing dissolved metals in solution. He is also a coof book, chemical cycles in the history the earth. Sedimentary exhalative sedex type deposits syngenetic stratiform, bedded znpb deposits hosted by finegrained clastic sedimentary rocks. Maynard therefore includes mississippi valley lead. At present, highgrade iron ore deposits formed by hydrothermal and supergene enrichment of proterozoic banded iron formations constitute the most important source for iron ores, with only some magmatic and skarntype iron ore deposits being mined. Throughout the report individual deposits are defined as being more than 2,000 meters from the nearest adjacent deposit. Students who gain less than 40% in the exam will be considered to have failed the course.
Sedimentary iron deposits, from which almost all iron is obtained, can therefore be viewed as one of the worlds great mineral treasures. A very common location for concentrated ore deposits is along faults and what were originally open fractures vein ore deposits see image to right. Petrology of ore deposits university of south alabama. Commercial deposits of metals come in a seemingly endless variety formed by many different geological processes. May 03, 2015 the ore is picked up with dieselpowered shovels, loaded into trucks, and hauled to the primary crusher. A classification scheme for ore deposits best classification. Within the near future, porphyry and sedimentary deposits are expected to dominate the resource scene for copper. The most common is silica, which forms a number of materials, including silica sand, sand and gravel, and flint.
The definition for sedimentary ore deposits adopted in this book is formed by sedimentary processes. The mechanism of formation is remarkably similar to that of the other hydrothermal. In this twostage basinscale model, gold and arsenic are introduced early into black shale and turbidite basins during sedimentation and diagenesis stage 1 and concentrated to ore. A mineral vein is formed when minerals precipitate in a fracture. Geochemistry of sedimentary ore deposits and, as a coauthor, sedimentology of shale. These are ores of copper, zinc, and lead in massive iron sulfide lenses that are conformable with enveloping lava flows and volcaniclastic sediments. Ores formed by igneous processes within the earth 3. Copper deposits in sedimentary and volcanogenic rocks. The majority of ore deposits of both iron and manganese are of sedimentary origin.
Also, to a minor extent, they occur in volcanic sediments. Pdf mineral deposits ore deposit environments formation of mineral deposits introduction the hydrologic cycle the rock cycle types of sedimentary. In teaching geochemistry, i realized that the best examples for many chemical processes are drawn from the study of ore deposits. Geochemical characteristics of sedimentary manganese. Introduction surficial earth processes sedimentary ore deposit environments sedimentary mineral deposits 1 deposits formed by sedimentation ironstone, calcium carbonate, chert, sulfur, uranium, copper. Inset shows scanning micro xray fluorescence xrf map of zinc zn. The two zoning sequences, beginning nearest the source of the metals, are. In this paper, geological characteristics of deposits, provenances, depositional environment and metallogenic process of main sedimentary ores are.
Geochemistry of sedimentary ore deposits rose 1984 eos. This short course focuses on 1 the types of basins in which major sediment hosted ore deposits occur, and 2 the controls of basin types on ore hosting sedimentary environments and ore forming processes. Magmatic ore deposits magmatic ore deposits are those which are formed during crystallization of a magma, deep underground. Maslennikov2 1 codes arc centre of excellence in ore deposits, university of tasmania, private bag 126, hobart, tasmania, australia 7001. The process of sedimentation results in the formation of some important mineral deposits viz. Ores from sedimentary processes residual deposits of bauxite residual deposits are an important group of sedimentary related ores formed by surface processes. This publication is available from the geological survey of wyoming. A chemical sedimentary ore is one in which the concentration of ore minerals accumulated as a result of precipitation from solutions at the earths surface.
Nov 17, 2012 an introduction to sedimentary ore deposits is to geologists. Multiple constraints from chospbsr isotopic compositions. Ore deposits formed in sedimentary environments chapter 5 ore. The metals are derived from bedrock, pass through the weathering. The resources of sedimentary and hydrothermal mn deposits are wide spread in turkey, and the total reserves are approximately 50 mt 1,2. The occurrence of some manganese deposits in the keonjhar district of odisha are believed to have formed by this process where by manganese at one level has been remobilised to the. Dear colleagues, this special issue of minerals, entitled sedimentary ore deposits. This dissolved kind of gold is called invisible gold, as it can only be found through chemical analysis. This paper presents evidence and arguments that carbonaceous sedimentary rocks were a source for au and as in sedimenthosted orogenic and carlintype gold deposits and develops a corresponding genetic model. A carbonaceous sedimentary sourcerock model for carlin. The u concentration in sedimentary phosphorite is generally between 50 and 200 ppm, but can be as high as 3,000 ppm, making it an increasingly important source of u for the nuclear industry. The manganese deposits of the thrace basin, occurring at the transition from limestone deposition below to clastic deposition above, are the most important sedimentary type deposits of turkey figure 1. The occurrence of a reeenriched mineral does not necessarily correlate with economic feasibility of mining that mineral deposit.
These three types may be considered as a spectrum of basemetal ore deposits which form in sedimentary rocks at some time during the evolution of a sedimentary basin. Kong, zhigang wu, yue liang, ting zhang, feng meng, xuyang lu, lin and yang, g. Sedimenthosted copper deposits are stratabound, that is, they are restricted to a narrow range of layers within a sedimentary sequence but do not necessarily follow sedimentary bedding. Pdf economic geology sedimentary ore deposits find, read and cite all the research you need on researchgate. Sedimentary exhalative deposits sedex deposits are ore deposits which are interpreted to have been formed by release of ore bearing hydrothermal fluids into a water reservoir usually the ocean, resulting in the precipitation of stratiform ore.
They are the only source of aluminium, even though aluminium is quite abundant, making up 8. A zoning sequence represents the natural order of increasing solubilities of the metallic sulphides and other minerals in ore forming solutions. The ore is rarely in fissure veins, but mostly in deposits of an irregular kind. This course provides a nontechnical introduction to the basic concepts of. The main ore minerals within the sedimentary rockhosted iron deposits in. The first, and by far the most important, is banded iron formations bifs, so.
Mineral deposits form in a variety of complex geologic settings such as continental magmatic arcs, sedimentary basins, and evaporite deposits. Finely disseminated ore deposits are great to find, but even more impressive are ore deposits that are concentrated over a small area. Pdf a carbonaceous sedimentary sourcerock model for carlin. The concentration of rees in some sedimentary phosphorites is comparable to the worlds richest igneous and chinese claytype ree deposits.
Pdf introduction to sedimentary ore deposits researchgate. The major source of zinc in the future will very likely be the. These deposits include but are not restricted to, sedimentary ores of iron and manganese, sedimentaryexhalative massive sulphide deposits, metalliferous black. The rocks which they lie upon were deposited just prior to the mineralizing event, while the overlying rocks were deposited just after all three layers being deposited at essentially the same time in terms of the geological time frame. They are epigenetic and diagenetic, that is, they are formed after the host sediment is deposited, but in most cases, prior to lithification of the host. For those who do not have the filemaker application, microsoftexcel. Igneous, metamorphic, and sedimentary ore deposits fig 1, a, b einaudi, 2000,stated that all mineral deposits can be classified into three types based on process, namely magmatic deposits, hydrothermal deposits, and surfacial deposits formed by surface and groundwater. Nomenclature for this class of sedimenthosted, cudominated sulfide deposits is problematic. These deposits include but are not restricted to, sedimentary ores of iron and manganese, sedimentary exhalative massive sulphide deposits, metalliferous black. At the primary crusher, the ore is reduced to 4 cm and passed by conveyor belt to the rod mill, which is in a closed circuit with a classifier, to grind the ore to 20 mesh. Geochemical characteristics of sedimentary manganese deposit. The deposit can consist of massive ores in some cases, a nd disseminations of rare minerals in others.
Geochemistry of sedimentary ore deposits wiley online library. Pdf economic geology sedimentary ore deposits researchgate. Sedimentary mineral deposits and the evolution of earths nearsurface environments. The deposits found in other parts of the world are products of diverse, wellrecognized, hy. Geochemistry of sedimentary ore deposits rose 1984. Deposits which form on the earths surface in the form of a sedimentary layer are also syngenetic. The main ore of aluminium is bauxite, not a mineral. The deposit is named after the carlin mine, the first large deposit of this type. Consequently, we initiated a course at the university of cincinnati entitled sedimentary. Other deposits form in rocks deposited in shallowmarine, deltaic, and nonmarine environments by the movement and reaction of interstratal brines whose metal content is derived from buried sedimentary and volcanic rocks. These deposits are characterized by invisible typically microscopic andor dissolved gold in arsenic rich pyrite and arsenopyrite. A thesis submitted to the faculty of the department of geology in partial fulfillment of the requirements for the degree of master of science in the graduate college the university of arizona 1961 i. Geologic criteria for the assessment of sedimentary.
Dense, physically, and chemically resistant minerals including cassiterite tin ore, gold and diamonds, can be concentrated by these processes into usually small, but high grade, ore deposits. Carlintype gold deposits are sedimenthosted disseminated gold deposits. The framework of the resulting ore deposit model is built on a mineral systems approach kreuzer and others, 2008. This book is an outgrowth of my interest in the chemistry of sedimentary rocks. Introduce the student to major ore deposits geodynamics of ore formation processes ore forming processes in dependence of geotectonic environments examine and identify overall similarities and to highlight deposit specific characteristics. Analysis on mineralization mechanism of sedimentary iron ore. Ore minerals minerals with economic value are ore minerals minerals often associated with ore minerals but which do not have economic value are gangue minerals key to economic deposits are geochemical traps metals are transported and precipitated in a very concentrated fashion gold is almost 1,000,000 times less abundant than is iron economic. Introduction ore deposits are crustal concentrations of useful elements that can be exploited at a pro. Sedimentary deposits are formed through the erosion, transportation, and redeposition of minerals that can survive the rigors of transportation.
The host rock for the mineralization can range from ultramafic to felsic. Placer deposits are surface deposits formed by sedimentary processes of weathering, erosion, transport and deposition. Mcqueen crc leme, australian national university, canberra, act 0200 and school of rehs, university of canberra, act 2601. Pdf a carbonaceous sedimentary sourcerock model for. Primary expressions of ore deposits a well known aspect of ore deposit expression is the association of particular ore types with particular host rock assemblages, i. Pdf sedimentary ore depositssedimentary uranium deposits. The major uranium and trona deposits are found in tertiary sediments in basin centers, whereas economic bentonite deposits are usually found in cretaceous strata on the flanks ofbasins. Iron is the most abundant metal used in water distribution, so scales formed on the interiors of iron pipes are by far the most abundant type of scale encountered. In this class are ore deposits that have been formed by the action of meteoric waters, that is, water derived from the air rain, etc. Mar 01, 2015 sedimentary exhalative deposits sedex deposits are ore deposits that are interpreted to have been formed by release of ore bearing hydrothermal fluids into a water reservoir usually the ocean, resulting in the precipitation of stratiform ore gu et al. Successful exploration for these accumulations, now that most of those easily spotted on the surface have been found, requires a knowledge of the processes responsible for their formation and the timing of those processes.
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