Die Grafitlagerstätte Zettlitz - Geologische Bearbeitung des Rohstoffvorkommens
Research output: Thesis › Master's Thesis › Research
Within the Waldviertel Region, organic-rich black shales of the Proterozoic Variegated Sequence host graphite deposits of economic importance. New theories interpret the Variegated Sequence as part of the Moravian complex experiencing a Variscan metamorphic overprint. The open pit Zettlitz deposit is the major graphite exposure in this region. Since 1855 more than 350.00 t graphite had been mined and processed until mining activities ceased in 1967. In the course of this thesis, the deposit was investigated by airborne surveying, geological mapping, geochemical investigations (AAS, XRF, ICP-MS, LECO combustion, SEM) and Raman spectroscopy on carbonaceous material (RSCM). Drone-supported photogrammetric surveying established a high-resolution digital elevation model of the mine. Within the pit, carbonate-poor graphitic shales with a TOC (total organic carbon) up to 61 weight% are found in a normal fault-bounded block. The black shales are underlain by scapolite bearing calcite marbles and overlain by thin quartzite layers and pegmatite bearing gneisses and micaschists. Pyrite, kyanite, dravite, phlogopite, phengite and amphibole are enriched in thin schistosity-parallel layers in a matrix of orthoclase, oligoclase, quartz and graphite. RSCM data characterize the carbonaceous material as well-crystallized with a formation temperature of 534 ± 50 °C within the amphibolite facies. The overprinting pressure can be estimated by a phengite-barometer and indicates 7 to 12 kbar. XRF and ICP-MS data show the typical chemical composition of non-mineralized black shales. The rare earth element (REE) pattern is characteristic for continental crustal rocks with an enrichment of the light and a depletion of the heavy REE and a distinct Eu-anomaly. V/Cr ratios indicate sapropelitic deposition conditions. The overall low sulfur-content implies a prevailing oxic, nutrient-rich environment with short euxinic periods (formation of pyrite-layers). The negative correlation between TOC and detritus shows a dilution of the organic matter by detrital (Al-rich) input into the sedimentation basin. The association of the black shales with marble indicates the formation in a small sapropelitic basin, evolving on a coastal carbonate system. The local presence of quartzite layers occurs due to temporary input of fine-grained quartz into this basin. Transgression- and regression-phases lead to the formation of the overlaying metasediments gneiss and micaschists.
|Translated title of the contribution||The graphite mine Zettlitz - geological investigations on the deposit|
|Award date||1 Jul 2016|
|Publication status||Published - 2016|