The source regions of mid-ocean ridge basalts (MORB) are heterogeneous, consisting of chemically and lithologically distinct domains of variable size. Partial melting of such heterogeneous mantle sources gives rise to diverse isotopic compositions of MORB and abyssal peridotites. Variations in radiogenic isotope ratios in MORB are attributed to mixing of melts derived from enriched and depleted...

[1] The initial oceanic crust along volcanic passive margins is a factor of 3 greater than that of typical oceanic crust (20 versus 6–7 km). Convection driven by the edge of the continental lithosphere may cause mantle material to circulate through the shallow zone of significant melting beneath the nascent ocean basin and cause the volume of melted mantle to exceed that required to replace the...

The late Precambrian Shadli Metavolcanics of SE Egypt constitute a slightly metamorphosed bimodal sequence that has been previously interpreted as manifesting volcanic activity at an island arc. We report the first Rb-Sr geochronologic, trace element (including REE), and Nd isotopic data for these rocks. Two types of basalt are recognized, the stratigraphically lower suite having compositions l...

Older and younger granitoids are widespread throughout the basement rocks of NE Egypt. Therefore, they are played a significant role in the evolution of the Pan-African crust. The Wadi El Sheikh-Gabal Saint Katherine area comprise three distinctive magmatic granitoid suites, namely: (1) calc-alkaline older quartz monzodiorite-tonalite suite (COG), (2) calcalkaline younger monzogranite suite (CY...

The viscosity of lavas erupted at volcanic arcs varies over orders of magnitude. A comparison of the relative abundance of viscous lava dome eruptions indicates that the average viscosity of arc lavas also varies considerably between arcs. It is shown that for continental or transitional arcs with little within-arc crustal deformation and without underlying slab windows or tears, average lava v...

Bulk-rock major and trace element geochemistry of a range of eclogite, garnet blueschist and garnet amphibolite rocks from northern New Caledonia has been determined in order to geochemically characterise subducted oceanic crust. The rocks experienced peak metamorphic conditions of 1.9 GPa and 600 jC and represent excellent samples of oceanic crust that was subducted to depths of approximately ...

Abstract Due to its size and observable record of ancient rock, Mars is key understanding crustal formation on planetary bodies, including Venus Earth, which may have derived their first stable crust from mantle-overturn melting. Recent evidence that martian contains an evolved component supports inferences a pervasive, buried feldspathic the crust. With data Compact Reconnaissance Imaging Spec...

Introduction: Deconvolution of thermal emission spectra from Mars orbiting spacecraft, in-situ analysis of martian rocks by Mars Pathfinder, Spirit and Opportunity rovers, as well as investigation of martian meteorites, all point towards a wide magmatic diversity at the surface of the planet. Compositions varying from olivine-rich basalt to high-silica granite / rhyolite through basaltic andesi...