Magmatic and post-magmatic phenomena in the Karkonosze granite and its metamorphic envelope (West Sudetes, SW Poland)

Abstract

The Karkonosze granitoid, one of the biggest plutonic bodies in the Sudetes, is located in the marginal part of the present-day Bohemian Massif. Due to its internal complexity, textural diversity and abundance of mineral species, the pluton has intrigued and captured the interest of generations of geologists, mineralogists, petrologists and enthusiasts of Earth sciences. The intrusion belongs to a younger, late-to post-orogenic Magmatic and post-magmatic Mineralogical studies of the Karkonosze granite (ca. 322-312 Ma) and its surroundings in West Sudetes (SW Poland) have provided data on Nb-Ta-REE minerals from pegmatites in the NE part of the pluton and several new finds of Ag minerals and 15 oxygenic Bi phases, hitherto not reported from the massif. The Karkonosze pegmatites are enriched in HREE as fergusonite-(Y) or xenotime-(Y) appear in almost every studied pegmatite, together with a subordinate assemblage of the aeschynite, euxenite or columbite group. The abundance of LREE minerals such as allanite-(Ce) and the monazite group, correlates inversely with the Nb-Ta-Ti minerals, whilst an early generation of monazite-(Ce) revealed an exceptionally high amount of Nd (up to 22 wt.% of Nd 2 O 3 ). The physical and chemical conditions during the magmatic and post-magmatic processes were reconstructed and the effects of contact metamorphism in amphibolites from hornfelsed zones examined. Changes in solution composition and concentration at the early magmatic stage (825-920ºC), pegmatitic stage overlapping with hydrothermal (560°C which ended at 160-90°C) and clearly hydrothermal stage (400 to 110°C) were studied in detail by means of melt and fluid inclusions in quartz. Furthermore, post-magmatic fluids, including some enriched in Li and B, were identified in rock-forming quartz from the whole pluton. In turn, study of the amphibolites indicates that the pair cummingtonite + anorthite or the presence of Ca-rich plagioclase with actinolite seem to be reliable mineral proxies of the thermal impact of the granitoid body on amphibolites in its envelope. The inferred conditions of the contact processes (450-550°C, 2.5-4.8 kbar) point to an elevated geothermal gradient (ca. 32-45°C/km) probably reflecting the heat flow induced by the Karkonosze intrusion. Moreover, despite the textural and mineral changes imposed by regional and contact metamorphism, the amphibolites have their pre-metamorphic (magmatic) geochemical features undisturbed.Key words: Karkonosze pluton; Melt and fluid inclusions; Nb-Ta-REE pegmatites; Contact zone amphibolites.Acta Geologica Polonica, Vol. 66 (2016) phase (325-290 Ma) of the intense granitoid magmatism in the Sudetes (ca. 340-290 Ma) which produced several large plutons (cf. e.g., Mazur et al. 2007; ObercDziedzic et al. 2013). The formation of the intrusion is correlated with a relatively early stage of that phase in Late Carboniferous times (Awdankiewicz et al. 2010) due to coupled tectonic and magmatic processes involving both mantle and crustal sources . As a consequence, the batholith...

Drainage evolution in the Polish Sudeten Foreland in the context of European fluvial archives

“…The Sudeten Massif in the extreme SW of Poland, in the core of the Variscan orogeny, experienced pervasive deformation, metamorphism, and granitic magmatism. This region was also affected at this time by NW–SE-oriented left-lateral strike-slip faulting (including slip on the Sudetic Boundary Fault and Intra-Sudetic Fault), creating a collage of fragmented crustal blocks of extreme complexity (e.g., Aleksandrowski et al, 1997; Aleksandrowski and Mazur, 2002; Franke and Żelaźniewicz, 2002; Gordon et al, 2005; Jeřábek et al, 2016; Kozłowski et al, 2016; Fig. 1).…”

Zircon U-Pb Dating of Magmatism and Mineralizing Hydrothermal Activity in the Variscan Karkonosze Massif and Its Eastern Metamorphic Cover (SW Poland)

“…The quarry contains finely crystalline (equigranular) aplogranite hosted in an older, porphyritic variety and medium-and coarse-grained monzogranite. All are locally cut by aplite veins, pegmatite bodies and quartz veins and veinlets with Mo-W-Sn-Bi-Fe-As-Cu-S mineralization [16,31,[41][42][43][44][45][46][47][48][49][50][51], and U-Th and REE mineralization [47,49]. Most ore mineralization is found in the northwestern part of the quarry, in quartz veins (with ores) from 1 to 25 mm thick.…”

“…The Michałowice quarry is located about 3 km east of Szklarska Poręba (Figure 1). Extensive mineralization with sulfides of Mo, Fe, and Cu-As, as well as minerals bearing W, Sn, Th and REE, occurs in pegmatites and in quartz veins cutting coarse-grained porphyritic granite [41,43,46,[52][53][54]. Molybdenite and pyrite dominate in grey quartz veins with variable thickness, from a few mm to about 2 cm.…”

Minerály pegmatitových hnízd z okolí Jablonce nad Nisou (krkonošsko-jizerský pluton) - část I. silikáty

“…V polské části krkonošsko-jizerského plutonu, kde jsou pegmatitová tělesa a hnízda rovněž častým jevem, je jejich mineralogická prozkoumanost mnohem větší než v české části a je tam patrně i díky tomu popsáno také větší množství minerálů. Například zde byly popsány: gadolinit-(Y), monazit-(Ce), monazit-(Nd), xenotim, fergusonit-(Y), cheralit-(Nd), columbit, pyrit, galenit, sfalerit, tetraedrit, ryzí stříbro, ryzí zlato, ryzí bismut, magnetit, hematit, rutil, anatas, brookit, kasiterit, wolframit, scheelit, fluorapatit, almandin-spes-sartin (Kozłowski, Sachanbiński 2007), aeschynit-(Y) (Kozłowski et al 2016), kristiansenit (Evans et al 2018, liandradit, ixiolit (Matyszczak 2018) a další.…”

“…Peraluminické minerály (granát, andalusit, muskovit a Al-bohatý turmalín) a S-typové mateřské granity ukazují, že studované pegmatity patří do LCT skupiny (Černý, Ercit 2005) ve srovnání s většinou pegmatitů krkonošskojizerském plutonu, kde I-typové granity produkovaly NYF pegmatity (Kozłowski, Sachanbiński 2007;Kozłowski et al 2016).…”