Differentiation der Pegmatite des Millstätter See-Rückens

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Abstract

Permian pegmatites of the Millstatt Seerücken are located in the Millstatt complex of the Koralpe-Wölz nappe system. The Millstatt complex consists of paragneiss to micaschist, amphibolite, calc-silicate rock and marble in which pegmatites are situated. They are boudinaged and show a diffuse contact to the surrounding host rock. In most cases they are concordant to the surrounding rock. Beside normal pegmatites, spodumene-pegmatite outcrops can be found near Edling, southwest of the so called Kreuzstein (new occurrence) and Lug-ins-Land. Spodumene bearing roll blocks can be found near the Egelsee. During field work 172 samples had been collected and then muskovites had been separated and measured with LA-ICP-MS and SEM-EDX. In special zoned pegmatites every zone had been sampled. Main elements were measured with SEM-EDX and trace elements with LA-ICP-MS. From pegmatites with high trace element contents in muskovite, thin sections had been prepared and petrographically processed. Muskovites in pegmatites can reach maximum trace element contents of: Li (642 ppm), Be (123 ppm), Rb (2369 ppm), Nb (385 ppm), Sn (650 ppm), Cs (264 ppm) and Ta (280 ppm). Pegmatites of the Millstatt Seerücken are low to high differentiated with a K/Rb value between 34 and 366. The geochemical data predicts that the pegmatites were formed during a single event and they show many geochemical similarities compared to the works of Ahrer (2014), Gassner (2001), Senzenberger (2001) and Sweda (2016). The classification scheme based on pegmatites with granitic origin form Cerný & Burt (1984), isn’t very suitable for pegmatites of the Millstatt Seerücken. Pegmatites in the W of the Millstatt Seerücken are in general more differentiated then pegmatites in the E, except of the Wollanig. Maps show the trace element contents of Li, Cs, Sn, Nb and Ta in muskovite. Li, Nb and Ta doesn’t correlate very well with the diffentiation grade. Sn and Cs fits very well with the differentiation grade. The trace element content of muskovite can’t be used as indicator for the presence of ore minerals, like cassiterite, columbite or pollucite. Further investigations are necessary to estimate the spodumene ore deposit potential of the Millstatt Seerücken.

Details

Translated title of the contributionDifferentiation of pegmatites of the Millstatt Seerücken
Original languageGerman
QualificationDipl.-Ing.
Supervisors/Advisors
Award date7 Apr 2017
Publication statusPublished - 2017