نتایج جستجو برای: basaltic
تعداد نتایج: 2375 فیلتر نتایج به سال:
Abstract Normally, volatiles in silicate melts are ephemeral components that escape as gases when the melt reaches fluid saturation. When saturation occurs at elevated pressure, magmatic fluids may have large amounts of oxide solute dissolved, less volatile, and resemble viscous gels. In Cyprus we rare case solutes a coexist with H 2 O saturated basaltic to boninitic glasses. Quenching was indu...
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 Kalkarindji continental flood basalt province of northern Australia erupted in the mid Cambrian (c. 511 505 Ma). It now consists of scattered basaltic lava fields, the most extensive being the Antrim Plateau Volcanics (APV) a semi-continuous outcrop (c. 50,000 km) reaching a maximum thickness of 1.1 km. Cropping out predominately in the SW of the APV, close to the top of the basalt successi...
[1] The Mössbauer spectrometer on Spirit measured the oxidation state of Fe, identified Fe-bearing phases, and measured relative abundances of Fe among those phases for surface materials on the plains and in the Columbia Hills of Gusev crater. Eight Fe-bearing phases were identified: olivine, pyroxene, ilmenite, magnetite, nanophase ferric oxide (npOx), hematite, goethite, and a Fe-sulfate. Adi...
Orientation of the eruption fissures and composition of the lavas of the Miyakejima volcano is indicative of the competitive processes of the regional tectonic stress and the local stress generated by the activity of a magma plumbing system beneath the volcano. We examined the distributions and magmatic compositions of 23 fissures that formed within the last 2800 years, based on a field survey ...
Multi-element abundances in twenty-four samples from the Serra Geral continental flood basalt system (Parana Basin) were determined by INAA to assess the trace element signature of primary magmatric sources. Isotopic Sr and Nd data were obtained on a 24-sample composite and three individual samples of the suite to constrain the influences of older enriched material. Twenty basaltic samples have...
Volcanic rocks along the Panama Canal present a world-class opportunity to examine the relationship between arc magmatism, tectonic forcing, wet and dry magmas, and volcanic structures. Major and trace element geochemistry of Canal volcanic rocks indicate a significant petrologic transition at 21-25 Ma. Oligocene Bas Obispo Fm. rocks have large negative Nb-Ta anomalies, low HREE, fluid mobile e...
During explosive eruptions, a suspension of gas and pyroclasts rises rapidly within a conduit. Here, we have analysed textures preserved in the walls of a pyroclastic feeder dyke of the AD 1886 Tarawera basaltic Plinian fissure eruption. The samples examined consist of basaltic ash and scoria plastered onto a conduit wall of a coherent rhyolite dome and a welded rhyolitic dome breccia. We exami...
Experiments were conducted to determine the water solubility of alkali basalts from Etna, Stromboli and Vesuvius volcanoes, Italy. The basaltic melts were equilibrated at 1,200°C with pure water, under oxidized conditions, and at pressures ranging from 163 to 3,842 bars. Our results show that at pressures above 1 kbar, alkali basalts dissolve more water than typical mid-ocean ridge basalts (MOR...
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