There must be a transition from continuous porous flow to transient formation of melt-filled fractures in the region of magma transport below oceanic spreading centers. This transition may occur at permeability barriers that impede porous flow of melt, at the base of the oceanic crust and within the lower crust. We summarize evidence for formation of melt-filled lenses at the base of the crust ...

The effects of particulate matter (PM) from diesel and leaded gasoline motor vehicles exhaust emissions on sulfation of granites, syenite and gabbro stones have been experimentally studied. Abundant gypsum crystals and corrosion features developed on stones covered with diesel PM (DPM) following 72 h exposure to 100 ppm SO2 at a relative humidity of 100%. In contrast, very small amounts of gyps...

Amphibolite blocks from an Archaean (2.9 Ga) trondhjemite-agmatite complex in the Lewisian at Gruinard Bay have a varied trace element and R E E content. Whilst some of the variability is attributable to element mobility during high-grade metamorphism and subsequent trondhjemite magmatism, it is for the main part considered to be a primary feature of the amphibolites. The observed trace element...

Introduction The mineralization at Waterfall Gorge was first exploited in 1865 for its copper. In 1908 nickel was reported in the ore, and in 1950s PGEs were reported (Maske and Cawthorn, 1986). Quantitative data on all these metals was presented by Lightfoot et al. (1984). Despite subsequent exploration no further economic resources have been defined, although geochemical modeling suggests the...

Magmatic augites reacted with high temperature aqueous solutions to form secondary calcic pyroxenes during the subsolidus cooling of the Skaergaard intrusion. Secondary, hydrothermal clinopyroxenes replace wall rock igneous augites at the margins of veins filled with calcic amphibole. These veins are up to several millimeters wide and tens of meters in length. Hydrothermal clinopyroxenes are a ...