An Upper Carboniferous tonstein of volcanic origin

摘要: Previous work on the mineralogy of volcanic supra-Wyrley Yard tonstein is extended to include opaque minerals. This has led a better understanding major and trace element geochemistry tonstein. The complete mineral assemblage kaolinite (dominant) with minor quartz, K-mica, zircon, apatite, pyrite, sphalerite, galena, rutile, dolomite, barytes, goethite organic matter. Information location in been obtained by using autoradiography fission track radiography, electron probe analysing separated fractions an optical spectrograph. This enabled diagenetic history individual elements be determined, composition compared igneous material. high concentration Th, U, Pb, Sn, Bi, Y, Be B tonstein, low Ti, Cr, V, Ni, Cu Co indicative acidic ash. A source Armorican orogenic belt postulated, based contrast basaltic Carboniferous volcanism also concentrations Pb Zn.