نتایج جستجو برای: basaltic composition

تعداد نتایج: 261472  

Journal: :Frontiers in microbiology 2015
Pauline A. Henri Céline Rommevaux-Jestin Françoise Lesongeur Adam Mumford David Emerson Anne Godfroy Bénédicte Ménez

To explore the capability of basaltic glass to support the growth of chemosynthetic microorganisms, complementary in situ and in vitro colonization experiments were performed. Microbial colonizers containing synthetic tholeitic basaltic glasses, either enriched in reduced or oxidized iron, were deployed off-axis from the Mid Atlantic Ridge on surface sediments of the abyssal plain (35°N; 29°W)....

2009
R. Dasgupta W. S. Kiefer A. H. Treiman

Introduction: Until recently, the SNC meteorites represented the only source of information about martian igneous processes [1]. This changed with the Mars Exploration Rovers which have analyzed basalts on the surface of Mars in both Gusev Crater and Meridiani Planum. These basalts are thought to be much older than the basaltic SNC meteorites [2] and have significantly different bulk chemistry ...

2012
Kamal Abdel-Rahman

Harrat Lunayyir is a basaltic volcanic field in NW Saudi Arabia. Lava flows are basaltic to basanitic in composition, and the Holocene flows are alkali olivine basalts. The volcanic field contains about 50 cones that were constructed on Precambrian crystalline rocks along an N-S axis. The dominantly basaltic lavas of Harrat Lunayyir have been divided based on their erosion characteristics into ...

2012
Lisa M. Nigro Kate Harris Beth N. Orcutt Andrew Hyde Samuel Clayton-Luce Keir Becker Andreas Teske

The microbiology of subsurface, hydrothermally influenced basaltic crust flanking mid-ocean ridges has remained understudied, due to the difficulty in accessing the subsurface environment. The instrumented boreholes resulting from scientific ocean drilling offer access to samples of the formation fluids circulating through oceanic crust. We analyzed the phylogenetic diversity of bacterial commu...

2016
G La Spina M Burton M De' Michieli Vitturi F Arzilli

Timescales of magma ascent in conduit models are typically assumed to be much longer than crystallization and gas exsolution for basaltic eruptions. However, it is now recognized that basaltic magmas may rise fast enough for disequilibrium processes to play a key role on the ascent dynamics. The quantification of the characteristic times for crystallization and exsolution processes are fundamen...

2010
I. Fleischer J. Brückner C. Schröder W. Farrand E. Tréguier R. V. Morris G. Klingelhöfer K. Herkenhoff D. Mittlefehldt J. Ashley M. Golombek J. R. Johnson B. Jolliff S. W. Squyres C. Weitz R. Gellert P. A. de Souza B. A. Cohen

[1] Numerous loose rocks with dimensions of a few centimeters to tens of centimeters and with no obvious physical relationship to outcrop rocks have been observed along the traverse of the Mars Exploration Rover Opportunity. To date, about a dozen of these rocks have been analyzed with Opportunity’s contact instruments, providing information about elemental chemistry (Alpha Particle X‐ray Spect...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Brent Grocholski Krystle Catalli Sang-Heon Shim Vitali Prakapenka

The discovery of a phase transition in Mg-silicate perovskite (Pv) to postperovskite (pPv) at lowermost mantle pressure-temperature (P - T) conditions may provide an explanation for the discontinuous increase in shear wave velocity found in some regions at a depth range of 200 to 400 km above the core-mantle boundary, hereafter the D('') discontinuity. However, recent studies on binary and tern...

2015
S. Wiesmaier D. Morgavi C. J. Renggli D. Perugini C. P. De Campos K.-U. Hess W. Ertel-Ingrisch Y. Lavallée D. B. Dingwell

In order to explore the materials’ complexity induced by bubbles rising through mixing magmas, bubbleadvection experiments have been performed, employing natural silicate melts at magmatic temperatures. A cylinder of basaltic glass was placed below a cylinder of rhyolitic glass. Upon melting, bubbles formed from interstitial air. During the course of the experimental runs, those bubbles rose vi...

Journal: :Science 1986
C M Pieters J W Head S Pratt W Patterson J Garvin V L Barsukov A T Basilevsky I L Khodakovsky A S Selivanov A S Panfilov Y M Gektin Y M Narayeva

Multispectral images of the basaltic surface of Venus obtained by Venera 13 were processed to remove the effects of orange-colored incident radiation resulting from interactions with the thick Venusian atmosphere. At visible wavelengths the surface of Venus appears dark and without significant color. High-temperature laboratory reflectance spectra of basaltic materials indicate that these resul...

2016
Wolfgang Bach

This contribution assesses the availability of catabolic energy for microbial life during water-rock reactions in the flanks of mid-ocean ridges, where basaltic and ultramafic rocks interact with circulating seawater. In addition to equilibrium thermodynamic computations, results for kinetic reaction paths are presented. In these calculations, it is assumed that dissolution of olivine and basal...

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