Title: Contrasting Styles of Magmatic Zoning in the Central Moldanubian Pluton
Abstract:Within the Central Moldanubian Pluton, three strongly peraluminous granite intrusion events were recognized (Breiter et al. 1997, Breiter and Koller 1999) (Fig.1). The oldest one, the Lasenice granite...Within the Central Moldanubian Pluton, three strongly peraluminous granite intrusion events were recognized (Breiter et al. 1997, Breiter and Koller 1999) (Fig.1). The oldest one, the Lasenice granite, was produced by minimum melting of metasedimentary material during the thermal peak of the Variscan metamorphism. The main stage of intrusion history is represented by the suite of the Eimio, Eisgarn s.s., and muscovite granites. The original high-K peraluminous melt, which was rich in Zr, Th and REE, underwent an intensive fractionation process towards the enrichment in Na, P, F, Li, Rb, Sn, Nb, U and Ta. The last melting episode produced deep-seated stocks of Zvule type. This melt was evolved as concerns major elements, but, in contrast to the previous melt, not able to produce LILE and Sn, Nb, U, Ta-enrichment. Two of the studied granite bodies show remarkable primary magmatic zoning. Eisgarn granite s.s. forms an elliptical, petrographically and chemically well zoned body between the towns of Gmund and Nova Bystoice. Its rim facies petrographically resembles the Eimio granite containing large perthitized orthoclase phenocrysts, smaller sub-automorph sericitized oligoclase, biotite rich in accessory apatite, zircon and monazite, and muscovite with relics of andalusite. The core-facies contains, besides relatively scarce and often partly resorbed perthite phenocrysts, also small automorphic columns of not-perthitized Kfs, and nearly automorph, only slightly perthitized albite. Muscovite prevails over strongly chloritized accessory-poor biotite. Andalusite is rare or absent. Besides old isometric Mn-poor apatite, also young Mn-rich interstitial apatite is present. The Eisgarn body (Fig. 2) shows distinct zoning patterns of nearly all analysed elements: an increase in elements such as Rb, Na, P, and F and a decrease in K, Ca, Fe, Mg, Th, Zr, Sr etc. from the contact to the centre. The isolines conform with the contacts with the older granites and crystalline rocks on the NW, N, E, and SE margins. In the SW, the continuation of the intrusion is covered by Tertiary and Quaternary sediments of Contrasting Styles of Magmatic Zoning in the Central Moldanubian PlutonRead More
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
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