Geologisch-lagerstättenkundliche Untersuchung von basischen Hartgesteinen im Raum Maishofen/Viehhofen (Salzburg)

Research output: ThesisMaster's ThesisResearch

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Abstract

Within the western part of the Northern Greywacke Zone (Eastern Alps, Austria) basic metavolcanics of Devonian age are very common. These metabasic rocks intercalate with siliciclastic sequences of the Schattberg-Fm. (Silurian-Devonian-Carboniferous?) and the Löhnersbach-Fm. (Ordovican-Devonian). The area of the Zeller Furche, especally near Maishofen/Viehhofen (Zell am See, Salzburg), comprises thick metavolcanic rocks which are part of the Metabasics-group containing a large amount of metabasalts. An exceptionally thick metabasalt-sequence was found in the area of Ratzenstein (Maishofen), which is intercalated by fine-grained, siliciclastic layers (mainly slates) of low thicknesses. Metabasalt-sequences of the Schernergraben (Viehhofen) show larger thicknesses of fine- to coarse-grained intercalations of metasediments (slates and metasandstones). The general dip is horizontal to slightly inclined (up to 15 degrees) to North. Due to tectonic movement tilted layers with steeper dipping angles (up to 60 degrees) and South or Southeast dipping direction can be measured locally. In thin sections of the metabasalt rocks porphyric to subophitic textures were found, whereby large, sometimes idiomorphic, lath-shaped feldspar (plagioclase) and pyroxene phenocrysts (Augite) are embedded within a fine-grained matrix of chlorite, quartz, sericite and leukoxene. These minerals and texture indicate a basic, primary magmatic protolith which had been affected by a lowgrade, greenschist facies metamorphism. The analysis of technical parameters revealed extremely good rock properties. Abrasion values (LA-test) are significantly below of 20 and the polished stone value (PSV-test) is above of 50. It can be noted that these analysed rocks, both mineralogic-petrographically, as well as geochemically are metabasalts, which are considered to be “bergfrei” mineral resources in the sense of § 3 of the MinRoG (as amended in 2011). In the working area of Maishofen/Viehhofen there are large resources of valuable basic hard rocks which represent, due to their qualitiy and quantity, a mineable metabasalt deposit. For further spatial planning/land use regulation this highgrad metabasalt deposit should be absolutely considered.

Details

Translated title of the contributionGeological examination of basic hard rocks in the area of Maishofen/Viehhofen (Salzburg)
Original languageGerman
QualificationDipl.-Ing.
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Award date4 Apr 2014
Publication statusPublished - 2014