Kinetic and fluid dynamic constraints on deepseated magma migration rates suggest ascent velocities in the range 10 to 30 m/s, 10 -1 to 10m/s and 10 -2 to 5m/s for kimberlitic, garnet peridotite-bearing and spinel peridotite-bearing alkalic magmas. These rates virtually demand translithospheric magma transport by a fracture as opposed to diapiric mechanism. The hypothesis that volatile exsoluti...

To study the characteristics and genetic constraints on alkalic-type epithermal Au mineralisation, here we use example of Tuvatu Au-Ag deposit in Fiji, with an emphasis detailed, quantitative mineralogy. mineralisation is hosted a weakly altered potassic monzonite parallel sided-veins K-feldspar, biotite, sericite, calcite, quartz, epidote-bearing propylitic or sericite-rich selvages. Petrograp...

Volcanism on Earth is known to occur in three tectonic settings: divergent plate boundaries (such as mid-ocean ridges), convergent plate boundaries (such as island arcs), and hot spots. We report volcanism on the 135 million-year-old Pacific Plate not belonging to any of these categories. Small alkalic volcanoes form from small percent melts and originate in the asthenosphere, as implied by the...

Abstract The late-tectonic 511.4 ± 0.6 Ma-old Nomatsaus intrusion (Donkerhoek batholith, Damara orogen, Namibia) consists of moderately peraluminous, magnesian, calc-alkalic to calcic granites similar I-type worldwide. Major and trace-element variations LREE HREE concentrations in evolved rocks imply that the fractionated mineral assemblage includes biotite, Fe–Ti oxides, zircon, plagioclase mo...