An ore deposit formed by magmatic segregation, generally in mafic rocks and layered intrusions, as crystals of metallic oxides or from an immiscible sulfide liquid. Ore deposits formed by lateral secretion are formed by metamorphic reactions during shearing, which liberate mineral constituents such as quartz, sulfides, gold, carbonates, and oxides from deforming rocks, and focus these constituents into zones of reduced pressure or dilation such as faults. Magmatic sulfide deposits models 1, 2b, 5a, 5b, 6a, 6b, and 7a. Models of environments and geometries linking mantle plumes to magma chambers and high level intrusions are illustrated in figs. Magmatic deposits deposits in which the ore minerals have crystallized directly from a magma. While a magma may start as a homogeneous liquid, magmatic segregation. Geology, genesis, and exploration for magmatic nicupge. The host rock for the mineralization can range from ultramafic to felsic. The oreforming magmatichydrothermal system of the piaotang wsn deposit jiangxi, china as seen from limica geochemistry. Discrimination between magmatic and hydrothermal nicu. If you continue browsing the site, you agree to the use of cookies on this website. Magmatic ore deposits in layered intrusionsdescriptive model. Geology, genesis, and exploration for magmatic pgecu. Through the magmatic segregation process, one or more minerals are concentrated locally during the cooling of magma.
View test prep magmatic ore deposits from geol 6960 at the university of oklahoma. Magmatic segregation is an oreforming process, in which the valuable minerals are concentrated by settling them out from cooling magma. We then use these data to discuss the evolution of uppercrustal magmatichydrothermal systems and speculate on how a range of vapor evolution paths might explain the formation of. In order to form a large porphyry deposit such as bingham, utah, cu, au, and s would need to be scavenged from 250 km3 of magma assuming typical magmatic concentrations and transported to the site of ore formation near the top of. Experimental determination of au solubility in rhyolite. Pdf triggers for the formation of porphyry ore deposits in. Much more uncommon than maficultramafic magmatic ore deposits. This monograph on magmatic ore deposits has resulted from a symposium held at stanford university on november 12 and, 1966. Students who gain less than 40% in the exam will be considered to have failed the course, irrespective of the semestermodule mark. Mineral deposit mineral deposit magmatic cumulates. Discrimination between magmatic and hydrothermal nicupge. Geology, genesis, and exploration for magmatic pgecuni deposits c.
Geology, genesis, and exploration for magmatic pgecuni. Most magmatic nicupge sulphide deposits occur within longlived magma pathways fed by high degree partial melts of the mantle. A magmatic ore deposit is an accumulation of magmatic minerals. Although there are a large number of mineral deposits, this article takes into consideration only a few general themes as type examples. Magmatic sulfide ore deposits are products of natural smelting. Magmatic ore deposits magmatic ore deposits are those which are formed during crystallization of a magma, deep underground. Pdf triggers for the formation of porphyry ore deposits. Ore deposits formed by gravity settling due to magmatic. Triggers for the formation of porphyry ore deposits in magmatic arcs article pdf available in nature geoscience 611. Magmatic ore deposits are derived from accumulations of crystals of metallic oxides.
Magmatic base metals deposits chrome nickelcopper platinum group metals pgm magmatic deposits are so named because they are genetically linked with the evolution of magmas emplaced into the crust either continental or oceanic and are spatially found within rock types derived from the crystallization of such magmas. Magmatic ore deposits in layered intrusions descriptive. Ls ore deposits are mostly vein or stockwork style mineralization which is. Magmatic some mineral deposits, particularly those containing ni, cr and pt, form by the separation of the metal sulphide or oxides in the molten form, within an igneous melt before it crystallizes. Only students with a semestermodule mark of more than 50% and an exam mark of more than 35% will be. Magmatic sulfide ore deposits elements geoscienceworld. Sulfide ore deposits occupy a spectrum from accumulated pools of matte within small igneous intrusions or lava flows, mined primarily for ni and cu.
The most important beds in magmatic deposits are those of iron, titanium, vanadium, chromium, platinum, copper, nickel, cobalt, apatite, diamonds, niobiumtantalum, zirconium, and hafnium. Sulphide and silicate liquids are immiscible meaning they do not mix, so droplets of iron, copper, nickel and platinum sulphides that form at high temperatures and are denser than the surrounding silicate liquid magma sink to the base of the intrusion to form a cumulate layer, where they. Magmatic ore deposits form through processes that are, for the most part, normal aspects of. These deposits vary in shape and occur in igneous rocks that are related to them in origin. 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. Geology of rare earth deposits tracy bank, elliot roth, bret howard, evan granite. Magmatic sulfide deposits models 1, 2b, 5a, 5b, 6a, 6b. Cu and au have been produced from tertiaryage deposits hosted in ophiolites around the eastern mediterranean for over 5000 years. Geol 5606 exploration for magmatic ore deposits mineral exploration research centre, harquail school of earth sciences, goodman school of mines, laurentian university author. The formation of valuable minerals in magma that is cooling is. The deposit can consist of massive ores in some cases, and disseminations of rare minerals in others. Layered, ultramafic to mafic intrusions are uncommon in the geologic record, but host magmatic ore deposits containing most of the worlds economic concentrations of platinumgroup elements pge figs. The relationship of layered igneous intrusions and associated magmatic ore deposits to mantle plumes is discussed in the preceding chapters.
Magmatic deposits article about magmatic deposits by the. Ore deposits that form in and around igneous rock units as a result of mineral precipitation from aqueous solutions or hydrothermal fluids are. 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. The commonly used metals like aluminum, copper, iron, lead, zinc etc. Magmatic ore deposits are derived from accumulations of crystals of metallic oxides, or immiscible sulfide, or oxide liquids that formed during the cooling and crystallization of magma, typically with mafic to ultramafic compositions. Complexes segregated via magmatic processes and was subsequently modified by hydrothermal processes. Hydrothermal magnetite ore deposition was accompanied by the pervasive occurrence of actinolite. These deposits are mined primarily for their platinum, palladium, and rhodium contents table 1. In many deposits, movement on the northsouth trending atacama fault zone was concurrent with ore deposition and intramineral dikes.
Generally found in mafic or ultramafic igneous rocks, typically layered complexes. We then use these data to discuss the evolution of uppercrustal magmatic hydrothermal systems and speculate on how a range of vapor evolution paths might explain the formation of porphyrystyle and epithermal ore deposits. Many important elements are found, on average, in the crust in very small amounts ppm ppb finding these elements in high concentrations is the exception and requires unusual geologic processes. We dedicate this collection of papers to professor tony naldrett, whose pioneering efforts laid the groundwork for so much of our current understanding regarding the genesis of magmatic nicupge deposits. The fate of magmatic sulfides during intrusion or eruption. Epithermal gold and silver in newfoundland and labrador matty mitchell prospectors resource room information circular number 8. Epithermal gold and silver in newfoundland and labrador.
All except three of the papers that were presented are published in this volume as well as some of the discussion and the summation of the symposium. Exploration for magmatic ore deposits 31 march 09 april 2020 harquail school of earth sciences goodman school of mines laurentian university course description. My general message is that saline magmatic fluids which produce epithermal ore deposits are chemi cally decoupled from the carapace of the magma and are derived from the area between the waterrich carapace and the brittleductile or lithostatichydro static transition. Geology of rare earth deposits national energy technology. It is assumed that there is relation between geothermal and epithermal ore deposits hedenquist et al.
Magmatic segregation can also take place as a result of the separation of sulphide and silicate liquids. All ore deposits of this type are hosted by dynamic magmatic systems. Midcretaceous magmatic evolution and intrusionrelated metallogeny of the tintina gold province, yukon and alaska craig j. Learn vocabulary, terms, and more with flashcards, games, and other study tools. No layering due to 100 higher mew, also due to lower density differences between minerals. This report is presented in portable document format pdf. These deposits are also sometimes called volcanichosted massive sulfide vhms deposits. Klein summary of relevant geologic, geoenvironmental, and geophysical information deposit geology magmatic sulfide deposits are sulfide mineral concentrations in mafic and ultramafic rocks derived from immiscible. Metallic ore deposits associated with mafic to ultramafic igneous rocks. Modular course exploration for magmatic ore deposits. The rocks that are formed as a result of magmatic segregation are called magmatic cumulates. Magmatic sulfide deposits models 1, 2b, 5a, 5b, 6a, 6b, and. Minerals form chief source of all the industrial metals and nonmetals. Volcanogenic massive sulfide ore deposits, also known as vms ore deposits, are a type of metal sulfide ore deposit, mainly copperzinc which are associated with and created by volcanicassociated hydrothermal events in submarine environments these deposits are also sometimes called volcanichosted massive sulfide vhms deposits.
Meaning of mineral deposits classification of mineral deposits mineral veins and composition of ore prospecting of mineral deposits metals extracted. The oreforming magmatichydrothermal system of the piaotang. Magmatic ore deposits chapter 2 ore deposit geology. This may occur without much hydrothermal fluid flow. Magmatic ore deposits are derived from accumulations of crystals of metallic. Magmatic deposits deposits of minerals formed deep in the earths crust during the solidification and crystallization of basic or alkaline magma containing high concentrations of valuable minerals. Magmatic ore deposits in layered intrusionsdescriptive model for. Copper deposits 3platinum group metal pgm deposits. The deposit can consist of massive ores in some cases, a nd disseminations of rare minerals in others. I made two specific choices in format that warrant some explanation. We then use these data to discuss the evolution of uppercrustal magmatichydrothermal systems and speculate on how a range of vapor evolution paths might explain the formation of porphyrystyle and epithermal ore deposits. Ore is hosted by pyritic quartzpebble conglomerates formed from. They occur within theigneous rock from which they were derived, such as a gabbro.
Ore deposits produced by magmatic segregation, with special reference to the nickel ores of the sudbury district, ontario stuart st. This study highlights the suitability of limicas as tracers of hydrothermal mineralizing events in worldclass wsn deposits associated with jurassic 190150 ma granites in china through the complex magmatichydrothermal evolution of the piaotang deposit south jiangxi. In the earths crust, the hydrothermal ore deposits occur in a fascinating diversity. Magmatic segregation is an ore forming process, in which the valuable minerals are concentrated by settling them out from cooling magma. Models of environments and geometries linking mantle. Ore deposits produced by magmatic segregation, with. Much less frequently magmatic deposits may occur in the form of flows that issue from volcanic vents for example, volcanic sulfur flows. Volcanogenic massive sulfide ore deposits, also known as vms ore deposits, are a type of metal sulfide ore deposit, mainly copperzinc which are associated with and created by volcanicassociated hydrothermal events in submarine environments. However, ore formation in the interior of modern hydrothermal magmatic systems is. Ore deposits produced by magmatic segregation, with special.
Midcretaceous magmatic evolution and intrusionrelated. A classification scheme for ore deposits best classification. Magmatic ore deposits, also known as orthomagmatic ore deposits, are deposits within igneous rocks or along their contacts in which ore minerals crystallised from a melt or were transported in a melt. To model the behavior of au in both oxidized and reduced magmatic environments, it is necessary to quantify the potentially mitigating effects of early crystallized magmatic phases on the au availability in melts reaching the porphyry environment. Magmatic segregation is a general term referring to any process by which one or more minerals become locally concentrated segregated during the cooling and crystallization of a magma. Some of these minerals are extremely rare and almost never encountered in common rocks, an example being alloys of the platinum metals. This work has been identified with a creative commons public domain mark 1. A number of processes that occur during cooling and crystallization of magmatic bodies can lead to the separation and concentration of minerals. Start studying ore deposits formed by gravity settling due to magmatic segregation.
Thus high concentrations of magmatic sulfides should not be present in rocks associated with orebodies. Holistic mineralsystem analysis for such deposits has some parallels with dominantly hydrothermal systems, but also some important differences. Up to 2002, vms deposits are estimated to have supplied over 5 billion t of sulphide ore franklin and. The mineral system approach applied to magmatic nicupge. Schedule geol 5606 exploration for magmatic ore deposits.
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