نتایج جستجو برای: mafic dykes

تعداد نتایج: 2656  

2006
J. B. WRIGHT

Plagioclase crystal fragments and a block of anorthosite occur in small basaltic dykes on the Jos Plateau. The anorthosite is unusual, for the feldspar is labradoritic, but the interstitial mineralogy is granitic rather than basic, displaying granophyric intergrowths in places. The anorthosite is probably not an intermediate stage in fractionation from a basic parent magma towards granite, sinc...

Journal: :Geological Magazine 1903

2014
Michael Krumbholz Christoph F. Hieronymus Steffi Burchardt Valentin R. Troll David C. Tanner Nadine Friese

Magmatic sheet intrusions (dykes) constitute the main form of magma transport in the Earth's crust. The size distribution of dykes is a crucial parameter that controls volcanic surface deformation and eruption rates and is required to realistically model volcano deformation for eruption forecasting. Here we present statistical analyses of 3,676 dyke thickness measurements from different tectoni...

2004
Stephanie Larissa Marsh

The goal of geovisualization is discovery and this can be hindered by a number of factors, including inadequate tools, that represent significant obstacles to the geovisualization thought process and require considerable effort to overcome (Dykes, forthcoming). Good software design using methods to support interaction can reduce these, but impediments are increasingly likely as geovisualization...

2007
Lisa R. Gaddis B. Ray

Clementine ultraviolet-visible (UVVIS) data are used to examine the compositions of 18 pyroclastic deposits (15 small, three large) at 13 sites on the Moon. Compositional variations among pyroclastic deposits largely result from differing amounts of new basaltic (or juvenile) matehal and reworked local matehal entrained in their ejecta upon eruption. Characterization of pyroclastic deposit comp...

2009
Gaud Pouliquen Roger Key Adrian Walker

The Xade Complex is an unexposed Y-shaped body, approximately 100 km long and 25km wide, located close to the western margin of the Kaapvaal craton in Botswana. The Complex is characterized by large coincident magnetic and gravity anomalies. It is completely covered by varying thicknesses of Kalahari sediments as well as by Karoo strata, which means that detailed analysis of high resolution air...

2015
Shohei Kaneko Masaaki Miyahara Eiji Ohtani Tomoko Arai Naohisa Hirao Kazuhisa Sato

High-pressure polymorphs recovered in terrestrial craters are evidence of meteoroid impact events on the Earth’s surface. Despite countless impact craters on the Moon, high-pressure polymorphs have not been reported to date in returned Apollo samples. On the other hand, recent studies report that the high-pressure polymorphs of silica, coesite and stishovite occur in shocked lunar meteorites. W...

2000
Neil C. Mitchell Maurice A. Tivey Pascal Gente

Observations from 145 submersible dives are used to create a database of mid-ocean ridge scarp topography and lithology. Seafloor lithologies are classified into extrusives, basaltic talus, dykes, gabbros and serpentinites, and the dive locations are broadly classified according to whether they are close to transform valleys and as a function of ridge spreading rate. The database is used to det...

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