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Showing 1 to 20 of 73 for “"hydrothermal alteration"”.
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The hydrothermal alteration of oceanic basalts by seawater
… temperatures. The mineralogy and chemistry of hydrothermally altered pillow basalts dredged from the Mid-Atlantic Ridge, and belonging to the greenschist facies, have been studied in order to determine the mineralogical changes that result from hyrdrothennal alteration, and to assess the …
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The hydrothermal alteration of oceanic basalts by seawater.
Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences.
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Hydrothermal alteration of upper oceanic crust formed at fast spreading rates
Hydrothermal circulation plays a fundamental role in the chemical transfer from deep in the Earth’s interior to the ocean crust, the oceans and the atmosphere. It is also on of the principal mechanisms for heat transfer from the mantle to the oceans, atmosphere and ultimately, outer space. This …
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Hydrothermal alteration and mineralization in the Climax molybdenum deposit, Climax, Colorado
Includes bibliographical references (pages 54-56).
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Modification of magnetic properties in granite during hydrothermal alteration (EPS-1 borehole, Upper Rhine Graben)
… “old” (Middle Carboniferous to Permo-Triassic) hydrothermal alteration history. This alteration history is generally subdivided into two stages. Stage I alteration is related to processes during magma cooling and solidification of the plutonic body in Middle Carboniferous times. Stage II …
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Mineralogy and geochemistry associated with hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy
… hyaloclastite from Ponza island, Italy, has been hydrothermally altered producing four distinct alteration zones based on XRD and field textures: (1) non-pervasive argillic zone; (2) propylitic zone; (3) silicic zone; and (4) sericitic zone. The unaltered hyaloclastite is a volcanic breccia with …
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Hydrothermal alteration of the ocean crust: insights from Macquarie Island and drilled in situ ocean crust
Hydrothermal circulation is a fundamental process in the formation and aging of the ocean crust, influencing its structure, physical and chemical properties, and the composition of the oceans and the mantle. The impact of hydrothermal circulation on mid-ocean ridge processes depends on the …
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Geochemical investigation of the hydrothermal alteration zone surrounding the greenstone-hosted Fazenda Brasileiro gold deposit, Bahia, Brasil
Includes bibliographical references (pages 380-393).
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Geochemical modeling of diagenesis, hydrothermal alteration, and unconformity-related uranium mineralization in the Athabasca Basin, Saskatchewan, Canada
… fluids or basement lithologies under diagenetic-hydrothermal conditions. However, there is controversy regarding whether U is ultimately derived from the basin or the basement, fluid flow mechanisms responsible for metal leaching and transport, and deposition mechanisms of ores. This study uses …
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Geochemical investigation of the hydrothermal alteration zone surrounding the greenstone-hosted Fazenda Brasileiro gold deposit, Bahia, Brasil
Includes bibliographical references (pages 380-393).
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Gold and Base Metal Mineralization, Hydrothermal Alteration and Vein Paragenesis in the Spring Valley Deposit, Pershing County, Nevada
… quartz-sericite-pyrite-carbonate ± tourmaline alteration. Initial classification as a porphyry gold system is thus disproved, and alternate orogenic and reduced intrusion-related gold interpretations are presented. Vein-related alteration is relatively consistent throughout the Quartz-eye …
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Quartz-kyanite pods in Proterozoic rocks in northern New Mexico : shear zone formation along an older hydrothermal alteration horizon
… pods was the result of weathering, hydrothermal alteration, or shearing. Geochemical differences between the quartz-kyanite/sericite schist pods and the sericite-rich layer that connects them suggest more than one alteration process. This study uses geochemical, structural, and …
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Quantitative Models of Fluid Flow, Chemical Reaction, and Stable Isotopic Fractionation and Their Application to Sediment Diagenesis and Hydrothermal Alteration
In this study, I develop a numerical model to predict dissolution and precipitation reactions by groundwater flow through temperature and pressure gradients in sedimentary basins. I incorporate chemical reaction into a transient model of groundwater flow equations that describes heat transfer and …
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Sub-surface geology, petrochemistry and hydrothermal alteration of Wells MW-03, MW-09 and MW-20 from Menengai geothermal field, Kenya
… caldera formation. The study defined seven hydrothermal alteration zones; Unaltered, Zeolite-Smectite (40-180°C), Quartz (above 180°), Illite (220°C), Chlorite (above 230°C), Epidote (240°C) and Wollastonite-Actinolite zone (above 280°C). Chlorite was noted in MW-03 and MW-20, illite zone …
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Geophysical Investigation of the Yellowstone Hydrothermal System
… and hot springs), yet little is known about the hydrothermally active zones hundreds of meters beneath the features. Transient electromagnetic (TEM) soundings and 2D direct current (DC) resistivity profiles show that hydrothermal alteration at active sites have a higher electrical conductivity …
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El Espino Iron-Oxide Copper Gold District, Coastal Cordillera of North-Central Chile, The
… Late Cretaceous multi-phase intermediate pluton. Hydrothermal alteration and mineralization was coeval with plutonism at 88 Ma. Both plutonism and hydrothermal alteration/mineralization were localized within a dilatational jog along a major transtensional north-south fault system that controlled …
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Argillic Alteration Associated With the Amethyst Vein System, Creede Mining District, Colorado (Illite, Smectite)
… and argillization are the two dominant facies of hydrothermal alteration associated with the deposit. Most silicification occurs in the intermediate and deep levels of the system and most argillized rock occurs high in the system.
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