Recent work in Barrovian metamorphic terranes has found that rocks experience peak metamorphic temperatures across several grades at similar times. This result is inconsistent with most geodynamic models of crustal over-thickening and conductive heating, wherein rocks which reach different metamorphic grades generally reach peak temperatures at different times. Instead, the presence of addition...

O's/O •6 ratios of thirteen tektites from Czechoslovakia, Libya, Texas, Indochina, Philippine Islands, Australia, Java, and Peru have been determined by the fluorine-extraction technique. All but one of these lie in relatively restricted range of Oas/O •6 ratio, with $ -9.6 to 10.4 per mil relative to the ocean-water standard. Tektites are therefore 0.5 to 1.5 per mil heavier than average grani...

[1] The slip behavior of major faults depends largely on the frictional and hydrologic properties of fault gouge. We report on laboratory experiments designed to measure the strength, friction constitutive properties, and permeability of a suite of saturated clay-rich fault gouges, including: a 50:50% mixture of montmorillonite-quartz, powdered illite shale, and powdered chlorite schist. Fricti...

A gravel pit in south central Stearns County, Minnesota exposes sand and gravel of the Merden Lake esker which is thought to have been deposited by a subglacial stream associated with the Wisconsinan-aged Superior Lobe of the Laurentide ice sheet. An analysis of these sediments was conducted from samples collected through a vertical trench on an east-facing exposure of the gravel pit. A total o...

Mineralogical, geochemical and fluid inclusion studies reveal two favourable environments for the localisation of beryl mineralisations in the Precambrian rocks of Egypt: (1) emerald-schist; and (2) beryl-specialised granitoid associations. Emerald occurs within the mica schists and is typically confined to the Nugrus major shear zone. However, beryl associated with granitoids occurs in pegmati...