• University of Tartu | Department of Geology

    SEM, EDS and EPMA studies reveal that the main secondary minerals are orthoclase, replacing plagioclase in granites and amphibolites, and chlorite, replacing hornblende in amphibolites. The extent of chemical and mineralogical alteration is closely related to microfractures. However, alteration has selectively changed the minerals.

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  • Hydrothermal mineral alteration patterns in the Mount Isa ...

    Four different types of hydrothermal alteration were identified with the hyperspectral mineral maps: (1) Metasomatic 1: white mica mineral maps show the spatial distribution of regional sodic–calcic alteration in metasedimentary successions of the Soldiers Cap Group in the Snake Creek Anticline.

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  • Carajas | Геологический портал GeoKniga

    Hydrothermal alteration effects on host amphibolites have been also investigated. The studied amphibolites occur as lenses or layers close to the contact with the gneissic basement or included in metagraywackes of the SaloboPojuca Group. Trace element chemistry of these rocks indicates that they are subalkaline basalts with tholeiitic affinity.

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  • PorterGeo Database Ore Deposit Description

    Localised zones of intense hydrothermal alteration, occuring as epidosite (epidote+quartz+sphene), is found within amphibolites (after basaltic rocks) (Yamana Gold, 2011). The deposit has been variously interpreted to be a metamorphosed porphyry copper or sediment (volcanic) hosted .

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  • Atlas alteration Thompson

    May 24, 2015· In most cases, the first step in describing hydrothermal alteration during field work or microscopy is the recognition of a secondary mineral. The Atlas assists in this identification by providing some of the criteria by which the mineral products of hydrothermal alteration are distinguished from their primary counterparts.

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  • Petrochemistry of Two Magnetite Bearing Systems in the ...

    pletely) by magnetite. Replacement of amphiboles/pyroxenes by magnetite may be hydrothermal and/or metamorphic in origin. The Binga amphibolites show some chlorite alteration (Figure (B)), which might have resulted from chloritisation of biotite and/or hornblende.

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  • Hydrothermal Alteration in Active Geothermal Fields ...

    Annual Review of Earth and Planetary Sciences Experimental and Theoretical Constraints on Hydrothermal Alteration Processes at MidOcean Ridges W E Seyfried, Jr Annual Review of Earth and Planetary Sciences MidOcean Ridge Hydrothermal Fluxes and the Chemical Composition of the Ocean H. Elderfield and and A. Schultz

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  • Calcite R040070 RRUFF Database: Raman, Xray, Infrared ...

    Meunier A, Clement J Y, Bouchet A, Beaufort D (1988) Chloritecalcite and corrensitedolomite crystallization during two superimposed events of hydrothermal alteration in the "Les Crêtes" granite, Vosges, France, The Canadian Mineralogist, 26, 413422

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  • The geological, mineralogical and petrological studies of ...

    Apr 07, 2017· The asbestos are derived from the alteration of amphibolites these is low grade products which exhibits fibrous habit fibers are long fine flexible and easily separable color variation from white to wooden brown the fibrous asbestos are found in between serpentine and trimolite actinolite schists these formed due to the metamorphism of ultra amafic rocks.

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  • Minerals | Free FullText | Hydrothermal Alteration in the ...

    Magnesiohornblende and tschermakite are consistent with amphibolite facies hydrothermal alteration, whereas tremolite and actinolite are consistent with greenschist facies hydrothermal alteration. Hydrothermal alteration of orthopyroxenes formed FeMgMn amphiboles whereas calcic amphiboles were formed from the hydrothermal alteration of clinopyroxenes [ 67 ].

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  • Progressive metamorphism of the Taitao Ophiolite; evidence ...

    The late development of veins and the systematically lower temperatures suggest that the veinforming alteration was due to offaxis hydrothermal alteration. Comparison between the Taitao ophiolite with its midocean ridge (MOR) affinity, and other ophiolites and MOR crusts, suggests that the Taitao ophiolite has many hydrothermal alteration features similar to those of MOR crusts.

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  • Hydrothermal fractionation of the rare earth elements and ...

    Hydrothermal fractionation of the rare earth elements and the genesis of the Lofdal REE deposit, Namibia. In: Simandl, and Neetz, M., (Eds.), Symposium on Strategic and Critical Materials

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  • The Carolina terrane in northwestern South Carolina,

    Figure 8. Plate tectonic model for the Carolina terrane from the Late Proterozoic (ca. 650 Ma) to immediately prior. to LaurentiaGondwana collision in the Carboniferous: (a) Neoproterozoic, (b) PrecambrianCambrian boundary, (c) Middle Cambrian, (d) .

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  • Hydrothermal alteration and Cu–Ni–PGE mobilization in the ...

    Hydrothermal alteration and Cu–Ni–PGE mobilization in the charnockitic rocks of the footwall of the South Kawishiwi intrusion, Duluth Complex, USA Zsolt Benkó, a, ⁎ Aberra Mogessie, a Ferenc Molnár, b Kurt Krenn, a Simon R. Poulson, c Steven Hauck, d Mark Severson, d and Greg B. Arehart c

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  • hydrothermal alteration Schlumberger Oilfield Glossary

    hydrothermal alteration English | Español: 1. n. [Geology] A change of preexisting rocks or minerals caused by the activity of hot solutions, such as fluids accompanying or heated by magma. Quartz, serpentine and chlorite are minerals commonly associated with hydrothermal alteration.

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  • Geology, geochemistry, hydrothermal alteration, and ...

    The steeply dipping silicified ridges that display sericitic alteration were inferred to be the root zone of this lithocap. Elevated values of trace elements such as Te, Bi, As, and Sb suggest that the Ronaldo prospect is mostly situated in a sericitic alteration zone related to a porphyrylike magmatichydrothermal source located at greater depth.

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  • USA Method for identifying hydrothermal ...

    An aerial natural gamma radiation survey is conducted over an exploration region. A change in the measured T1208/K40 ratio in the exploration region in contrast to a region known not to be hydrothermally altered identifies the exploration region as a hydrothermal alteration. A surface natural gamma radiation survey is conducted over the hydrothermally altered exploration region.

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