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Showing 1 to 20 of 26 for “"Ultramafic Rocks"”.
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Rubidium-strontium analyses of ultramafic rocks and the origin of peridotites.
Massachusetts Institute of Technology. Dept. of Geology and Geophysics. Thesis. 1965. Ph.D.
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Fluid-rock interaction on alpine-type ultramafic rocks from the Norwegian Caledonides
Alpine-type ultramafic rocks are tectonically emplaced from mantle into the crust. Their petrological and structural alterations occur during their path from deep-seated sources to their crustal emplacement. Therefore, these rocks are suitable for the study of fluid-rock interaction during the syn- …
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Surface detection of alkaline ultramafic rocks in semi-arid and arid terrains using spectral geological techniques
… into the spectral response of alkaline and other ultramafic rocks from arid and semi-arid regions. To date these rocks have not been investigated spectrally in a systematic fashion using the latest field and airborne imaging spectrometers. The objective was to determine how spectral geological …
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Lichens Of Ultramafic Rocks: A Multidisciplinary Approach To Understanding The Ecology Of An Understudied Organism In A Well-Studied System
… life forms of metal-rich habitats, including ultramafic rocks and soils; however, research on lichens of ultramafic habitats is limited, especially on the North American continent. A review of the published literature on lichens of ultramafic substrates in North America yielded a total of 437 …
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An experimental study on characterization of physical properties of ultramafic rocks and controls on evolution of fracture permeability during serpentinization at hydrothermal conditions
… experiments on cylindrically cored samples of ultramafic rocks. Each core had a well-mated through-going tensile fracture, to investigate evolution of fracture permeability during serpentinization. The samples were tested in a triaxial loading machine at an effective pressure of 30 MPa, and …
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Determining the physico-chemical conditions on the early earth : Barberton scientific drilling project, South Africa
Low-grade metabasites and hydrothermally altered ultramafic rocks comprise most of the ca. 3.5-3.2 Ga, Paleoarchean Barberton Greenstone Belt (BGB) of South Africa. However, PT-constraints and detailed petrological information on the variably altered mafic-ultramafic rocks are sparse and the nature …
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Ultramafic Alteration and the Cooling of Earth and Mars
This thesis deals with the influence of `ultramafic' rocks over the climate of planets. Ultramafic rocks, rich in Mg and Fe, are the most common rocks on Earth but exist primarily in the mantle and rarely outcrop on the surface. They are incredibly unstable under Earth's surface conditions where …
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Some geological aspects of radioactivity: The use of biotite in determination of geologic age by the strontium method. The use of lepidolite in determination of geologic age by the calcium method. The potassium content of ultramafic rocks and its heat contribution
Thesis. (Ph.D.) Massachusetts Institute of Technology. Dept. of Geology, 1952.
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Geology and Tectonic Significance of the Late Precambrian Eastern Blue Ridge Cover Sequence in Central Virginia
… in the Blue Ridge of central Virginia includes rocks of the Moneta Formation and the overlying Lynchburg Group. The Moneta Formation comprises arnphibolites, felsites and biotite gneisses that unconformably overlie the Grenville basement. The Lynchburg Group in central Virginia is divided into …
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Evaluating mantle and crustal processes using isotope geochemistry
… accurate mantle extraction ages for continental rocks. Chapter 2 examines the Re-Os isotopic composition of the Horoman massif, Japan. These data indicate that the Os isotope composition is controlled by the Re content, through radiogenic ingrowth, while the Re content is governed by the extent …
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Mass transfer and chemical interactions in subduction zones
… constraints from exhumed high-pressure rocks and erupted arc magmas, high pressure-temperature laboratory experiments, and thermodynamic calculations. Chapters 2 and 3 investigate the fluid-mediated reactions between mafic and ultramafic rocks at conditions relevant to the slab-mantle …
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Mass Transfer and Chemical Interactions in Subduction Zones
… constraints from exhumed high-pressure rocks and erupted arc magmas, high pressure-temperature laboratory experiments, and thermodynamic calculations. Chapters 2 and 3 investigate the fluid-mediated reactions between mafic and ultramafic rocks at conditions relevant to the slab-mantle …
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The origin and tectonic significance of the mafic-ultramafic association in the central Virginia Blue Ridge post-Grenville cover sequence
The question of whether the mafic and ultramafic rocks of the central Virginia Blue Ridge are part of a Late Proterozoic to Ordovician ophiolite-bearing sequence or part of an intrusive-extrusive sequence related to the Late Proterozoic Iapetan rifting has major implications for Appalachian …
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The geochemistry of methane isotopologues
… sediment-poor vent fields hosted in mafic and ultramafic rocks on slow- and ultraslow-spreading mid-ocean ridges. The data support a hypogene model whereby methane forms abiotically within plutonic rocks of the oceanic crust at temperatures above ca. 300 C during respeciation of magmatic …
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The geochemistry of methane isotopologues
… sediment-poor vent fields hosted in mafic and ultramafic rocks on slow- and ultraslow-spreading mid-ocean ridges. The data support a hypogene model whereby methane forms abiotically within plutonic rocks of the oceanic crust at temperatures above ca. 300 °C during respeciation of magmatic …
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The petrology, geochemistry and structure of the plutonic rocks of the Oman ophiolite
… chamber in which formed the layered mafic and ultramafic rocks of the Cumulate Sequence and the isotropic gabbros, diorites and trondhjemites of the High Level Intrusives. Structures and petrofabrics developed in the Mantle Sequence preserve lines and planes of mantle flow beneath the oceanic …
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Pining for an anomaly: Biogeochemical mapping of the Cobar Basin for mineral exploration at regional to local scales.
… than felsic intrusive and volcaniclastic rocks or Ordovician siliciclastic units. Micronutrients Ni, Co and Mn are elevated over ultramafic rocks. The needles display moderate to strong multielement biogeochemical responses to underlying mineralisation for ore-related elements including …
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Guiana Shield diamonds, the sub-cratonic lithosphere, and kimberlite emplacement in the upper crust.
… eroding as paleo-placers from Roraima Supergroup rocks, but may have been primarily derived from older ultramafic rocks (≥ 2 Ga) with a high H2O/CO2 volatile budget. These ancient diamonds also contain inclusions that preserve high Cr, Al, Mg, and low Ca, suggesting a harzburgitic paragenesis. …
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Nickel laterites, origin and climate
… climatic data for regions where suitable ultramafic rocks are exposed and defining the climatic conditions favourable for the formation of nickel laterite deposits, the optimum temperatures and precipitation rates for nickel laterite development can be identified. A compilation of …
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Physiological and Phylogenetic Studies of the Biogeography of Alkaliphilic Heterotrophic Bacteria from Serpentinizing Habitats
Serpentinization occurs when ultramafic rocks containing the mineral olivine react with water to produce highly reducing conditions, which are commonly coincident with high concentrations of hydrogen. Hydrogen provides an energy source for microbial metabolism and in combination with mineral …
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