21 research outputs found
Espectroscopia infravermelha à baixa temperatura em quartzos e ametistas com altas concentrações de OH e H2O
STABLE ISOTOPE COMPOSITIONS OF ZN- AND PB-CARBONATES: THEIR POSSIBLE ROLE IN EXPLORATION OF NON-SULPHIDE ORES.
Chronology of magmatism and mineralization in the Kassandra mining area, Greece:The potentials and limitations of dating hydrothermal illites
Isotope dating of residual kaolin deposits in Europe (Tirschenreuth, Germany and St. Yrieix, France)
A new illite deposit near Le-Puy-en-Velay (France):Genesis and usage for waste encapsulation
Mineral and geochemistry of clay-sized fractions from sediments of the Oligocene maar near Baruth (Saxony, Germany)
Twenty seven clay-sized (<2 μm) separates from drill core samples of the Upper Oligocene maar near Baruth, Saxony, were
mineralogically and chemically characterized using X-ray diffraction analysis coupled with the Rietveld method, X-ray fluorescence
analysis, scanning and transmission electron microscopy, and stable isotope analysis. The predominant minerals in the clay fractions
are kaolin minerals (kaolinite and halloysite) and opal-A. Abundant Fe- and smectite-rich illite-smectite mixed-layer minerals occur
exclusively in the lower turbidites and debris flows. Illite and beidellites are minor components. Accessory phases are anatase,
siderite, sanidine, quartz, albite-rich plagioclase, and pyrite. Four main detrital components were detected in the Upper Oligocene
maar sediments: 1) biogenic opal-A as diatom fragments, 2) disordered kaolinite (and halloysite) + illite + beidellite + Zr-rich anatase
from soils on granodioritic material, 3) Fe- and smectite-rich I-S from weathered basaltic volcanic material and 4) sporadic eolian
input of sanidine-bearing, probably phonolithic, ashes. The Mid-Miocene kaolinite-rich clays that cover the maar sediments were
derived from eroded saprolites on the Lausitz granodiorite. The δD and δ18O values of the kaolinite-rich clay fractions from various
lithologies indicate kaolinization at temperatures of ~15 ± 5 °C from meteoric waters that were isotopically heavier than present-day
meteoric waters. There is no evidence for hydrothermal clay formation in the maar