u-pb ages obtained on zircons from the investigated migmatites place new constraints on the evolution of the crustal rocks in the takab area. shrimp u-pb dating of inherited zircon in the melanosome parts of mafic migmatites from the takab complex gives a discordant age with an upper intercept of 2961±72 ma (mswd=0.5) and a lower intercept of 24.2±5.7 ma (mswd=1.7). in the concordia diagram, th...

dyke swarms emplacement constitutes one of the conspicuous features of the neoproterozoic arabian-nubian shield (ans) (~950-540ma). based on field investigations, petrographic and geochemical characteristics the dyke swarms in nw sinai (egypt) comprise of mafic (dolerite-trachy-basalt-basalt), intermediate (basaltic-andesite trachy-andesite) and felsic (rhyodacite-rhyolite) varieties. geochemic...

Global maps of thermal and fast neutron fluxes from the moon suggest three end-member compositional units. A high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks. The South Pole-Aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels, consistent with more mafic rocks. Th...

The paper studies accessory Cr-spinels from deep drill holes crossing the Nude-Poaz massif, which is a part of Monchegorsk mafic-ultramafic layered complex (2.5 Ga, Kola Peninsula, Russia). occur as two morphological types that differ in their chemical composition, i.e., first type are more aluminous, while second ferruginous and titaniferous. massif characterized by Fe-Ti trend known for intru...

Volcanic glass is deposited with trace amounts (0.1–0.6 wt.%) of undegassed magmatic water dissolved in the glass. After deposition, meteoric water penetrates into the glass structure mostly as molecular H2O. Due to the lower dD (‰) values of non-tropical meteoric waters and the 30‰ offset between volcanic glass and environmental water during hydration, secondary water imparts lighter hydrogen ...

Experimental studies show that K replacement of Na in triclinic plagioclase under hydrothermal conditions results directly in triclinic microcline without forming intermediate monoclinic orthoclase. These experiments bring laboratory and field evidence into agreement for the K-metasomatic origin of granites which contain exclusively microcline as the potash feldspar. Such replacements of a more...

Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) on the Mars Express spacecraft identify the distinct mafic, rock-forming minerals olivine, low-calcium pyroxene (LCP), and high-calcium pyroxene (HCP) on the surface of Mars. Olivine- and HCP-rich regions are found in deposits that span the age range of geologic units. However, LCP-rich regions are found on...