LOW-TEMPERATURE METASEDIMENTS FROM THE NIZKE-TATRY MTS. (WESTERN CARPATHIANS)

This paper describes the petrological and mineralogical features of th e quartz-muscovite metasandstones (QMM), a lithology found in the form of tectonic slices in an augen-gneissic environment N and W of Jaseni e, Nizke Tatry Mts., Western Carpathians. These rocks have an exemplar y psammitic texture, and are composed of detritic phases, represented by oval quartz grains, large muscovite flakes and sparse individual gr ains of albite and metamorphic phases consisting mainly of quartz and microcrystalline aggregate of muscovite-phengitic mica. Small amounts of tiny, metamorphic, newly formed albite and needle-like tourmaline a re accompanied by scattered scales of chlorite and crystals of magneti te. Neither the QMM nor the associated siderite-ankerite metasandstone s and phyllites (SAMP) contain biotite indicating that their metamorph ic degree did not reach the biotite subzone. The total content of alka lies in the metamorphic muscovite-phengites is fairly high (>0.86 per formula unit), thus, they should be illite-free and their estimated de gree of metamorphism should correspond to the epizone. This estimate i s also supported by the incomplete compositional and grain size equali zation between clastogenic and metamorphic white potash micas at their contacts. In contrast, the metamorphic white micas are considerably e nriched in the phengite molecule. The X-ray and selected area electron diffraction (SAD) analyses made to visualize and to measure the cryst allinity of individual carbonaceous matter (CM) particles revealed tha t most samples are composed of a mixture of anthracitic and graphitic carbon. While the anthracite is an indicator of very low metamorphism, the graphite first forms under greenschist facies conditions. A searc h for non-graphitizing carbons, such as shungite, skeleton crystals, o r fullerenes, which form under medium or high-grade metamorphism, has been unsuccessful. Thus, all the ill-ordered carbons in the samples de veloped under low-grade metamorphism. This conclusion supports the aut hors' earlier view that the rocks under study are metasediments and no t diaphthorites.