Example from the jiguanzui cuau deposit, eastern china. Some studies see below show that hydrothermal alteration of highsilica rhyolite produces adularia, clay minerals, silica minerals, disseminated pyrite and marcasite, zeolite minerals, iron oxides, native sulfur, and sulfate minerals. Sphalerite occurs with other sulphides in hydrothermal ore veins as with the specimens below, in disseminated deposits, in veins in igneous rocks or in contact metasomatic deposits. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Hydrothermal deposits are never formed from pure water, because pure water is a poor solvent of most ore minerals. In vms deposits, ore generally consists of sulfide or sulfosalt minerals that contain cu, pb, zn, ag, and or au. The mineralogical characteristics of the hydrothermal types. Hydrothermal alteration and mineralization zoning in ironoxidecuau vein deposits, near copiapo, chile douglas c. Hydrothermal mineral deposit, any concentration of metallic minerals formed by the precipitation of solids from hot mineralladen water hydrothermal solution. Eudialytehosted critical metal deposits potentially represent major sources of rare earth elements ree, zirconium and niobium. The zoning of the type hydrothermal alteration, mineralogical composition and spatial position within the ore body has permitted.
Mineral alteration an overview sciencedirect topics. Hydrothermal alteration involves waterrock interaction at temperatures above 50 c in association with plutonism or volcanic activity. Identification of hydrothermal alteration minerals associated with geothermal system using aster and hyperion satellite data. Hydrothermal alteration at the panorama formation, north pole. Zozulya, dmitry dzierzanowski, piotr and jokubauskas, petras 2015. Hydrothermal alteration is very important for mineral exploration, because it extends well beyond the limits of the ore, thereby allowing to focus exploration activity. Barton center for mineral resources, department of geosciences, university of arizona, tucson, arizona 85721, u. Mineral reactivity and evolution of surface properties article pdf available in clay minerals 361. The types of hydrothermal alteration were separated by the minerals assemblages formed through reaction of the wall rocks heat solutions with different chemical composition. Hydrothermal mineral deposits are those in which hot water serves as a concentrating, transporting, and depositing agent. When hot water contributes to changes in rocks, including mineral alteration and formation of veins, it is known as hydrothermal alteration.
Using aster image processing for hydrothermal alteration and key alteration minerals mapping. Methods to quantify hydrothermal alteration are used to. The integrated analysis of seismic rock properties, lithogeochemical data, and mineral compositional data, estimated via scanning electron microscopyenergy dispersive xray spectroscopy semeds, provides insight into the effects of hydrothermal alteration on seismic reflectivity in the footwall of the lalor volcanogenic massive sulfide vms deposit, manitoba, canada. Hydrothermal alteration is a ch emical replacement of the original minerals in a rock by new minerals where a hydrothermal fluid delivers the chemical reactants and removes the aqueous reaction products. Using aster image processing for hydrothermal alteration. Alteration mineral assemblages characterize the many varied hydrothermalchemical reactions that occur in active geothermal systems. A field and petrographic guide to hydrothermal alteration minerals. In metamorphic geology, a protolith designates a rock whose mineral assemblages. Hydrothermal alteration can be isochemical, like meta. The recognition of alteration mineral zoning can help identify hydrothermal fluid channel ways.
Hydrothermal alteration at the panorama formation, north. Several hydrothermal alteration assays have been carried out in teflon. Hydrothermal alteration of chevkinitegroup minerals. The minerals and mineral assemblages, especial clay minerals, would provide information on hydrothermal conditions. In the upper portion of the cored sequence to a depth of about 1200 m alteration is characterized by the deposition of clay minerals calcite quartz laumontite into open spaces such as vugs. The solutions are thought to arise in most cases from the action of deeply circulating water heated by magma. Minerals formed at an early stage may alter to other minerals as the process continues. Hydrothermal alteration mineralogy is essen tially uniform throughout the area explored. Hyperion data for mapping iron oxidehydroxide minerals and clay mineral.
In this work, we carried out a series of experiments to test the reactions occurring. Pdf identification of hydrothermal alteration minerals for. Identify and categorize the feed zones in the study wells. The minerals which compose the rocks are dissolved and new mineral formations are deposited in their place. The mineralogical characteristics of the hydrothermal. The extent of the alteration may be measured in millimeters or kilometers. The chemical methods available are numerous and each has specific advantages, limitations and fields of application. Hypo gene alteration has converted primary sodalime plagioclase into a variety of hydrothermal minerals including montmorillonite, micaceous clays, cal cite, wairakite, albite, kfeldspar, quartz and epi dote. Hydrothermal alteration, also referred to as wallrock alteration, is a general term that encompasses many processes by which rockforming minerals are altered due to reactions accompanying the flow of heated aqueous fluids along fractures and grain boundaries meyer and hemley, 1967. Using aster image processing for hydrothermal alteration and. Several hydrothermal alteration assays have been carried out in teflon reactors at 45, 60, 90, 120, 175 and 200c for periods of up to 1 y. Application of alteration minerals and thermal fluid.
Most of these minerals are encountered in olkaria as hydrothermal alteration minerals. Identify the hydrothermal alteration minerals and the history of alteration, and to understand the thermal evolution of the wells. The minerals typically occur in zonessections in field that reflect changing conditions of formation. Hydrothermal alteration occurs when hot waters free calcium and carbonate ions from separate sources, and these ions combine and precipitate calcite. Hydrothermal alteration and weathering crust of the earth. Hydrothermal clay mineral formation of east pacific rise. Hydrothermal minerals earth sciences museum university of. Hydrothermal alteration the wallrock on both sides of each veinlet is typically altered to varying degrees. The alteration may appear to be simply a color change or it may involve major textural, mineralogical andor chemical changes. This is what gives the canyon its spectacular colors. Alterations of clay minerals and zeolites in saturated nacl brine the mineralogical alterations of clay minerals and zeolites under hydrothermal conditions of 200 and 300 and 30 mpa pressure in nac1 are presented in table 2.
The first type is characteristic of the deeper parts of an orogenic hydrothermal system, and this g08024. Hydrothermal alteration and weathering crust of the. Hydrothermal alteration definition, mineral exploration. A great deal of effort has been devoted to the search for a key alteration mineral or assemblage that would provide a reliable general guide to ore. Hydrothermal alteration is a very complex process involving mineralogical, chemical and textural changes, resulting from the interaction of hot aqueous fluids with the rocks through which they pass, under evolving physicochemical conditions. Short wavelength infrared swir characteristics of hydrothermal alteration minerals in skarn deposits. Hydrothermal alteration is defined as any alteration of rocks or minerals by the reaction of hydrothermal fluid with preexisting solid phases.
The effect of chemical and temperature conditions on the occurrence of secondary minerals is well known, based on field observation and. Hydrothermal alteration assemblage maps were com piled from the following sources. The alteration is usually restricted to small regions characteristic of contact metamorphism where new minerals, clay minerals, zeolites, and hydroxides form in the presence. Quantifying hydrothermal alteration with normative minerals. Hydrothermal clay mineral formation of east pacific rise and bauer basin sediments. Hydrothermal alteration is a complex process involving mineralogical, chemical and textural changes, resulting from the interaction of hot aqueous fluids with the rocks through which they circulate, under evolving physicochemical conditions.
The list of minerals and mineral groups formed by hydrothermal alteration comprises 68 names and doubtless will be ex panded as research. Hydrothermal alteration styles in ancient and modern orogenic. In this report, we assigned various geochemical data to one of the. Hydrothermal fluids chemically attack the mineral constituents of the wall rocks, which tend to re. Alteration may occur through dissolution, ion exchange. The mineral assemblages of hydrothermal alteration in. Introduction hydrothermal alteration is a ch emical replacement of the original minerals in a rock by new. Hydrothermal alteration economic geology geoscienceworld. Pdf identification of hydrothermal alteration minerals associated. The three mineralisation types can be traced spatially andor temporally from one to another with some overlap. Pdf identification of hydrothermal alteration minerals. Other sources of heating that may be involved include energy released by radioactive decay or by faulting of the earths crust. Apr 30, 2015 o this alteration style is the most common in a variety of hydrothermal ore deposits and forms over a wide temperature range by hydrolysis of feldspars to form sericite finegrained white mica, with minor associated quartz, chlorite, and pyrite.
Hydrothermal alteration usgs publications repository. Hydrothermal alteration an overview sciencedirect topics. Macdonald, ray baginski, boguslaw kartashov, pavel m. Saponitic bentonite mined in the magan deposit toledo, spain, has been classified as a suitable clay barrier in the storage of high level radioactive waste. The zoning of the type hydrothermal alteration, mineralogical composition and. Introduction the interaction between hydrothermal fluids and the rocks through which they migrate alters the earlier formed primary. Alteration and secondary mineralization are most intense in the flow top breccias where waterrock ratios are presumed to have been the highest. Objectives identify lithological units of the study wells la9d and la10d. They are the most numerous of all classes of deposit. Hydrothermal alteration styles in ancient and modern. Pdf atlas of alteration a field and petrographic guide to hydrothermal alteration minerals get file pdf atlas ofintelalteration a field and petrographic guide to hydrothermal alteration minerals exe x c941f1f125b34df583e6888c51a1aab6 nl 822 my in hand works with at tgo phone sim. Pdf hydrothermal alteration of a saponitic bentonite. Hydrothermal minerals earth sciences museum university.
Schematic illustration of the scale of alteration and zonation of hydrothermal minerals surrounding epithermal auag deposits formed from nearneutral ph and reduced solutions simmons et al. It becomes an interesting area for remote sensing investigations to explore the new prospects of porphyry copper and vein type epithermal gold. This study focuses on the hydrothermal process at beattie, a neoarchean gold deposit hosted by. Hydrothermal alteration of volcanic host rocks involves the replacement of primary igneous glass and minerals pla gioclase, orthoclase, quartz, biotite, muscovite, amphibole, pyroxene, titanomagnetite with alteration minerals stable at the conditions of alteration, generally in the temperate range of 150400 c. Mineral associations in vesicles are common and consist of two or. Mineral deposits division university of british columbia. Pdf short wavelength infrared swir characteristics of. Geological association of canada, mineral deposits division, 1996 science 119 pages.
Importance of hydrothermal alteration and mineral exploration. At the end for hydrothermal alteration mapping a rgb composite images e. Alterationmineralization and veinstructure descriptions for each hole are found in the core descriptions contents list. Volcanic activity represents one of the main factors controlling the geological evolution of mars, whose morphology has remarkable counterparts on earth. Alteration mineral assemblages characterize the many varied hydrothermal chemical reactions that occur in active geothermal systems. Figure 6 color composite rgb showing abundance of hydrothermal alteration that is.
Identification of hydrothermal alteration minerals. These were based mostly on visual and binocular microscope observations of cut, wet surfaces, and specific alteration minerals were only distinguished where it was considered that unequivocal identification could be made. Aviris images showing propylitic assemblage minerals west of mineral creek. Major styles of mineralization and hydrothermal alteration. Hydrothermal alteration of plagioclase in granitic rocks from. The primary silicate minerals such as feldspar and amphibole are replaced by hydrothermal minerals stable at temperatures of about 400 c or less such as chlorite, epidote, muscovite and quartz. These areas were differentiated in order to characterize and contrast the geochemical signatures of solids and waters in a variety of mineralized areas. Hydrothermal fluids chemically attack the mineral constituents of the wall rocks, which tend to re equilibrate by forming new mineral assemblages that are in equilibrium with the new conditions. Elucidating the effects of hydrothermal alteration on.
The most characteristic minerals include sericite, quartz, chlorite, sulfides, epidote, zoisite, clinozoisite, leucoxene, clay minerals, calcite, and other carbonates. Quartz is the only abundant primary mineral that commonly resists destruction by hydrothermal processes. The most striking examples of hydrothermal alteration were the production. Whisman rd, mountain view, ca 94043, usa 2 csiro exploration and mining, arrc centre, kensington, wa 6102, australia 3australian centre for astrobiology, macquarie university, nsw 2109, australia. Mineral deposit mineral deposit hydrothermal solution. Secondary mineralization and hydrothermal alteration in. The mineral assemblages of hydrothermal alteration in slate. Hydrothermal copper deposits are often found in porphyritic igneous rocks. Hydrothermal alteration of plagioclase in granitic rocks. The effects of weathering and the minerals produced are often similar to the products of hydrothermal alteration insofar as the hydrous silicates are concerned.
At still lower temperatures, smectite or kaolinite can be the most important clay mineral. Subsurface geology and hydrothermal alteration of wells. The list of minerals and mineral groups formed by hydrothermal alteration comprises 68 names and doubtless will be expanded as research continues. Colin and patrick 2000 indicated that the success of the application of.
Some minerals, such as biotite, may be susceptible to alteration but on occasion form as an alteration product. Hydrothermal alteration zones associated with porphyry copper deposit. This study focuses on the hydrothermal process at beattie, a neoarchean gold deposit. The mineral components of bentonite are stable below.
Hydrothermal solutions in high temperature hydrothermalmagmatic systems of modern volcanism areas are saturated and often oversaturated owing to alteration of conditions when hydrothermae are overflowing to different hypsometric levels and from certain hydrogeological structures to others. Secondary mineralization and hydrothermal alteration in the. Geochemistry of hydrothermal alteration in volcanic rocks. Major styles of mineralization and hydrothermal alteration and. The effect of chemical and temperature conditions on the occurrence of secondary minerals is well known, based on field observation and mineral synthesis laboratory experiments. Alteration minerals form a group with unusual stability which exhibits a remarkable tendency toward convergence. It is the replacement of one rock by another of different mineralogical and chemical composition. Hydrothermal alteration and mineralization zoning in iron. The nwse trending central iranian volcanic belt hosts many wellknown porphyry copper deposits in iran.