specific elements (cr, al, ca, and si) and loss on ignition (loi) were used for semi-quantitative determination of the normative mineralogical composition of naturally occurring chromium ores in ophiolite complexes. by far the occurring ore minerals are complex both from the mineralogical and chemical viewpoints. the secondary minerals serpentine and cr-containing chlorite (kaemmererite) form n...

the lithologies of regions, which located near the collision zone, are very different from other geology setting. mapping in these areas needs extensive and exact studies and tools because of the variety of rocks, intensive tectonic uplift and complicated units. hyperspectral sensor is one of the most advanced tools with hundreds of bands that each measures a very narrow range of wavelengths an...

The northern Oman margin is a key area for understanding the emplacement of Semail Ophiolite and obduction processes in general. This study uses grid 2D-multichannel seismic lines tied to well data characterize offshore domain reappraises post-obduction history margin. West Muscat, Sohar basin, late Cretaceous Paleogene tectonic mega-sequence records syn- late-obduction stages deposition erosio...

The ultramafic portions of the Proterozoic ophiolite, Eastern Desert, Egypt, contain significant chromitite concentrations that are mainly located in the central and southern parts of the Eastern Desert as small and irregular bodies within a fully serpentinized dunite and harzburgite. Chromitite spinel exhibits a wide range of composition from high Cr to high Al varieties. The Cr# of chromian s...

[1] Abstract: Analysis of crystal size distributions (CSD) of plagioclase in gabbros from the Oman ophiolite indicates that cooling rates in the lower crust beneath a mediumto fast-spreading oceanic ridge did not vary smoothly with depth. Cooling rates in the upper half of the gabbro section were approximately 1.5–2 times faster than in the lower half of the gabbro section during igneous crysta...

Spinels from cumulus and non-cumulus members of the 0thris ophiolite display a considerable variation in composition. Cumulus pierites and gabbros contain either a primary chromite and/or a reaction spinel formed by reaction with co-existing sili?ate,-" (Cr--A1 varia tion) or intercumulus liquid (Cr--Fe variation). Non-cumulus peridotites contain spinels which vary along a Cr--A1 trend. Harzbur...

The Solund–Hyllestad–Lavik area affords an excellent opportunity to understand the ultrahigh-pressure Scandian orogeny because it contains a near-complete record of ophiolite emplacement, high-pressure metamorphism and large-scale extension. In this area, the Upper Allochthon was intruded by the c. 434 Ma Sogneskollen granodiorite and thrust eastward over the Middle ⁄ Lower Allochthon, probably...

The ophiolites of Othris, northern Greece, and Troodos, Cyprus, are of mixed lherzolite-harzburgite and harzburgite sub-type respectively. Within both ophiolites an entire spectrum of harzburgite, plagioclase harzburgite, lhcrzolite and plagioclase lherzolite interpreted respectively as residual and highly, moderately and slightly modified upper mantle has been recognised. Plagioclase lherzolit...

We investigated the crystal and structural behavior of several Cr-bearing spinels from the Archean chromitites of Amsaga (Mauritania). The chemical and structural data testified a retrograde metamorphism from amphibolite to greenschist facies, witnessed by relative changes in the amount of all the major oxides (Cr, Al, Mg, Fe2+, Fe3+), the relative proportion of Fe/Fetot as well as the structur...