نتایج جستجو برای: basalts
تعداد نتایج: 2061 فیلتر نتایج به سال:
V/Sc systematics in peridotites, mid-ocean ridge basalts and arc basalts are investigated to constrain the variation of fO2 in the asthenospheric mantle. V/Sc ratios are used here to ‘ see through’ those processes that can modify barometric fO2 determinations in mantle rocks and/or magmas: early fractional crystallization, degassing, crustal assimilation and mantle metasomatism. Melting models ...
The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and Mini-Thermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain </=25% megacrysts....
techniques and fractionation correcting to a 194Pt/ 95pt ratio of 0.9734 (38). 33. E. Anders and N. Grevesse, Geochim. Cosmochim. Acta 53, 197(1989). 34. M. P. Gorton, E. S. Schandl, A. J. Naldrett, Ocean Drilling Project Scientific Results, Leg 140, in press. 35. R. J. Walker et al., Geochim. Cosmochim. Acta 58, 4179 (1994); M. F. Horan, R. J. Walker, V. A. Fedorenko, G. K. Czamanske, ibid., i...
Microbial colonization and alteration of basaltic glass J. Einen, C. Kruber, L. Øvreås, I. H. Thorseth, and T. Torsvik Department of Biology, University of Bergen, Jahnebakken 5, N-5020 Bergen, Norway Department of Earth Science, University of Bergen, Allegt. 41, N-5007 Bergen, Norway Received: 20 December 2005 – Accepted: 5 January 2006 – Published: 7 March 2006 Correspondence to: J. Einen (jo...
the lut block in eastern iran is a micro-continental block within the convergent orogen between the arabian, eurasian and indian plates. large areas of the north-central, eastern, and western lut block are covered by volcanic rocks of paleogene, neogene and quaternary age. peak volcanic activity took place in the north-central part of the lut block during the eocene, and then dramatically decr...
E xtinctions have played an important role in the history of life by clearing out niches and fostering adaptive radiations. Major mass extinctions involving 70% to more than 90% of extant species occurred at least five times during the last 540 million years. The discovery by Alvarez et al. (1) that the end-Cretaceous (65 Mya) mass extinction coincided with evidence for the impact of an asteroi...
Introduction: Crystallization of the lunar magma ocean occurred ~4.4 Ga [e.g., 1-4] and produced three principal magma source regions [5-6]. These sources are characterized chemically by low titanium (Ti), high Ti, and high potassium, rare earth element, and phosphorous (KREEP) abundances. The KREEP component was produced after nearly complete solidification of the magma ocean and is highly enr...
The permeability k and porosity φ of vesicular basalts are measured. The relationship between k and φ reflects the formation and emplacement of the basalts and can be related to the crystal and vesicle microstructure obtained by image analysis. Standard theoretical models relating k and φ that work well for granular materials are unsuccessful for vesicular rocks due to the fundamental differenc...
The Boundary Conditions: Basalts from the Earth, the Moon, Mars, and Vesta are strongly depleted in elements that prefer to reside in the metallic state (siderophile elements). Therefore, it is believed that all these bodies have metallic cores. We do not yet have siderophile element analyses of venusian basalts, but we assume that Venus, too, as a terrestrial planet, has a metallic core. For t...
pillow basalts, belonging to late cretaceous yüksekova complex are extensivelly exposed around elazıg in eastern turkey. this unit is a part of southeastern anatolian ophiolite belt and the southern branch of the neotethys. it represents the products of intra- oceanic subduction volcanism and mainly comprises pillow lavas, dykes and associated with sedimentary rocks. pillow lavas and feeder dyk...
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