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Polymetamorphic evolution of pelites inferred from tourmaline zoning – the Rędziny hornfels case study at the eastern contact of the Karkonosze Granite, Sudetes, Poland

Majka J., Sęk M. P., Mazur S., Gołębiowska B., Pieczka A.

Mineralogia

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2018

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Vol. 49, iss. 1/4

17--34

EN

Tourmaline occurring in hornfelses from the eastern envelope of the Karkonosze Granite (Western Sudetes, Poland) reveals at least two stages of crystallization expressed by its complex zoning. The cores and mantles of the crystals probably grew during prograde metamorphism under intermediate pressure-temperature conditions reflected by increasing Mg, Ti and Ca. Outermost rims show enrichment in Al and Ca, indicating growth during contact metamorphism in the presence of an Al-saturating phase. The Ti-content in biotite indicates that the temperature of the contact metamorphic event did not exceed 650ºC. The presence of andalusite and the lack of garnet and cordierite also indicates pressure conditions of ~ 2-3 kbar, typical of the C1 bathozone of Carmichael (1978) or the P1 bathozone of Pattison (2001).

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Ti remobilization and sulphide/sulphoarsenide mineralization in amphibolites: effect of granite intrusion (the Karkonosze–Izera Massif, SW Poland)

Mochnacka K., Oberc-Dziedzic T., Mayer W., Pieczka A.

Geological Quarterly

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2008

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Vol. 52, No 4

349-349

EN

Our studies focus on ore mineralization in a contact-metamorphic aureole, using the Variscan Karkonosze Granite pluton as an example. The Karkonosze in trusion is enveloped by an Early Palaeozoic (about 500 Ma) metamorphic complex of the Izera–Kowary Unit composed of a diverse assemblage of gneisses, granitic gneisses, schists, amphibolites and marbles. The Budniki ore mineralization site was discovered in the early 1950's at the SE margin of the pluton. The uneconomic Ti-ox ide/sil i cate, Fe-Cu-Ni-Co-sulphide-sulphoarsenide, and uranium mineral deposits are hosted within amphibolites which were subjected to regional metamor phism fol lowed by contact meta - morphism. The Ti mineralization includes an ilmenite-titanite assemblage that originated from regional-metamorphic transformation of igneous Ti-bearing minerals, such as ilmenite and tschermakite, of the basic protoliths of amphibolites. During subsequent contact metamorphism, ilmenite was decomposed and, after wards, Al-rich titanite and rutile were formed. The Ti remobilization was coeval with an early stage of superimposed Fe-Cu-Ni-Co-sulphide/sulphoarsenide mineralization (pyrrhotite, pyrite, pentlandite, arsenopyrite, chalcopyrite, sphalerite and Fe-Ni-Co-As-S phases), related to the activity of the Karkonosze Granite hydrothermal system. The ore minerals formed successively within a wide range of temperatures (625–250gradeC).

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The geological significance of the Rb-Sr whole-rockisochron of hornfelsed schists from the Izerskie Garby Zone, Karkonosze-Izera block, southernwest Poland

Fila-Wójcicka E.

Acta Geologica Polonica

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2004

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Vol. 54, no. 3

407--411

EN

Preliminary Rb-Sr isotope data for hornfelsed schists from the "Stanislaw" quarry in the Izerskie Garby Zone are reported. An isochron based on three points representing three whole-rock samples yields an age of 333 [plus-minus] 4 Ma (Visean) and an initial 87Sr/86Sr ratio of 0.709567. The Rb-Sr age of 333 [plus-minus] 4 Ma, indicating the date of the Rb-Sr system closure, can be interpreted as the cessation of contact metamorphism in the Izerskie Garby Zone. The age of 333 [plus-minus] 4 Ma is close to the peak of contact metamorphism in this zone. Contact metamorphism and silification in the Izerskie Garby Zone were genetically related to the activity of the Variscan Karkonosze pluton. Contact metamorphism was older than the biotite cooling at ca. 320 Ma.

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Petrogenesis of the calc-silicate skarns from Garby Izerskie, Karkonosze-Izera block

Fila-Wójcicka E.

Acta Geologica Polonica

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2000

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Vol. 50, no. 2

211-222

EN

The exocontact skarns of the Garby Izerskie mountain group in Izera Mts (Sudetes, Southern Poland), which occur as intercalations in hornfelsed schists, were characterized by means of the paragenetic analysis. A number of parageneses were found, consisting of hedenbergite grossular, wollastonite, vesuvianite, albite, actinolite, calcite, epidote, quarz and fluorite. The skarn minerals formed in four stages of different physico-chemical conditions. Stage I, which took place during the prograde metamorphism in a quasi-isochemical system, resulted in crystallization of hedenbergite (ca. 500 stopni C), wollastonite and grossular (ca 600-650 stopni C) at p[static]=p[total]=p[fluid]=2kbar. The latter two minerals formed at peak metamorphic temperatures, when at ca 650 stopni C the fluids had a CO2 concentration of 30 molar percent. Stage II began the retrograde metamorphism, also in a quasi-isochemical system and resulted in the origin of vesuvianite, actinolite, prehnite, epidote and calcite pseudomorphs after wollastonite. Vesuvianite was the earliest retrograde mineral, which had probably started growing when the temperature decreased below 600-580 stopni C. Water activity increased during retrograde metamorphism at the expense of the CO2 activity, whose concentration was lower than 2 molar percent during the prehnite formation. Stage III comprised mainly silicification which began at least at 410 stopni C in an allochemical system; it could have partly overlapped stages I and II in time. Stage IV, which was mainly the fluorine metasomatosis at 360 to 110 stopni C developed also as an allochemical process. Thus, the skarns from Garby Izerskie are high-temperature calc-silicate varieties of the pyroxene-garnet-wollastonite type with the subsequent alteration of the calcic plagioclase to the sodic one and the silica and fluorine metasomatosis.