Amphibolites from the Szklarska Poręba hornfels belt, West Sudetes, SW Poland: magma genesis and implications for the break-up of Gondwana

2011 ◽  
Vol 101 (5) ◽  
pp. 1253-1272 ◽  
Author(s):  
Sławomir Ilnicki
Keyword(s):  
Magma Genesis ◽  
West Sudetes ◽  
Sw Poland ◽  
Break Up

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

2016 ◽  
Vol 66 (3) ◽  
pp. 456-476 ◽  
Author(s):  
Andrzej Kozłowski ◽  
Sławomir Ilnicki ◽  
Witold Matyszczak ◽  
Agnieszka Marcinowska
Keyword(s):  
Geothermal Gradient ◽  
Contact Metamorphism ◽  
Melt And Fluid Inclusions ◽  
Hydrothermal Stage ◽  
Magmatic Stage ◽  
West Sudetes ◽  
Sw Poland ◽  
Chemical Conditions ◽  
Physical And Chemical ◽  
Mineral Changes

AbstractMineralogical 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 Nd2O3). 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 (825-920°C), 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.

scholarly journals Not simply volcanoes – The Geoheritage of the Cretaceous System in the Land of the Extinct Volcanoes Geopark, West Sudetes (SW Poland)

2021 ◽  
pp. 3-22
Author(s):  
Piotr Migoń ◽  
Edyta Pijet-Migoń
Keyword(s):  
Large Scale ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
The Other ◽  
The West ◽  
Qualitative And Quantitative ◽  
Deformation Structures ◽  
Volcanic Geoheritage ◽  
West Sudetes ◽  
Sw Poland

Volcanic geoheritage is emphasized as the main asset and distinctive characteristic of the Land of Extinct Volcanoes Geopark in the West Sudetes (SW Poland). However, the geoheritage values of the region are not limited to the legacy of ancient volcanism but include various other elements. This paper explores the contribution of geosites that expose sedimentary rocks of Cretaceous age and landforms developed upon these rocks. Six localities from the Geopark area, included in the comprehensive regional inventory of geosites, are presented. They represent natural and man-made sandstone outcrops and show, among others, lithological variations, small- and large-scale post-sedimentary deformation structures, landforms arising from differential weathering (rock shelters, honeycombs), boulder fields and a sandstone xenolith in volcanic rocks. Next, five localities from outside the Geopark, but still within the Pogórze Kaczawskie region, are described. Qualitative and quantitative evaluation of both groups is attempted, and the results show that, in general, geosites within the Geopark rank higher. However at least two from the other group also have significant geotourist potential. Finally, a brief comparative analysis with other parts of the Sudetes, where Cretaceous sedimentary rocks occur, is offered.

Variscan progradeP-Tevolution and contact metamorphism in metabasites from the Sowia Dolina, Karkonosze-Izera massif, SW Poland

2011 ◽  
Vol 75 (1) ◽  
pp. 185-212 ◽  
Author(s):  
S. Ilnicki
Keyword(s):  
Hydrothermal Activity ◽  
Contact Metamorphism ◽  
Thermal Activity ◽  
Saxothuringian Zone ◽  
History Of ◽  
West Sudetes ◽  
Sw Poland ◽  
Two Stages ◽  
Pressure Changes ◽  
Quantitative Indicators

AbstractSeveral bodies of moderately foliated and porphyroblastic metabasites crop out on the SE side of the metamorphic cover of the Karkonosze granite within metapelites of the Sowia Dolina area (West Sudetes, Saxothuringian zone). Depending on the microstructural setting of the Ca-amphiboles in the rocks, different mineral-chemical trends have been determined for Si,XMg, AlVI,A[Na+K] which serve as semi-quantitative indicators of temperature and pressure changes. Porphyroblasts and prisms oblique to the main foliation in schistose metabasites show zoning from Mg-hornblende and actinolite to tschermakite, and then to Mg-hornblende (or actinolite). Matrix amphiboles and those in pressure shadows around some porphyroblasts have tschermakitic cores and actinolitic rims. Rarely, Ca-amphibole is accompanied in schists by late- to post-tectonic cummingtonite. Thermobarometric calculations involving empirically calibrated amphibole equilibria enable a reconstruction ofP-Tpaths for individual rocks and the unravelling of the metamorphic evolution of the metabasites. Peak metamorphic temperatures of 615–640°C and pressures of 7.3–8.2 kbar were preceded by a variably preserved earlier stage (T = 370–550°C, P = 2.8–6.2 kbar). The final metamorphic episode took place at 450–550°C and 2.5–4.8 kbar and is recorded particularly in rocks close to the Karkonosze pluton. The metabasites shed new light on the history of metamorphism in the Sowia Dolina area. The first two stages ofMP-MTmetamorphism, coeval with Variscan deformation events (continental collision, burial and subsequent exhumation), took place under epidote-amphibolite then amphibolite facies conditions. The last stage partly concurred with the final stages of Variscan deformation and overlapped the onset of thermal activity associated with the Karkonosze granite. This metamorphic event is documented by metabasites (occasionally cummingtonite-bearing) outcropping close to the granite. Finally, a prehnitebearing assemblage reflects retrograde re-equilibration under greenschist/sub-greenschist facies conditions (T<300–350°C,P<2.5–3 kbar), which might also be partly due to hydrothermal activity around the pluton.

Cambro-Ordovician vs Devono-Carboniferous geodynamic evolution of the Bohemian Massif: evidence from P–T–t studies in the Orlica–Śnieżnik Dome, SW Poland

2017 ◽  
Vol 156 (3) ◽  
pp. 447-470 ◽  
Author(s):  
MIROSŁAW JASTRZĘBSKI ◽  
BARTOSZ BUDZYŃ ◽  
WOJCIECH STAWIKOWSKI
Keyword(s):  
Bohemian Massif ◽  
Large Scale ◽  
Regional Metamorphism ◽  
Contact Metamorphism ◽  
Temperature Deformation ◽  
Geodynamic Evolution ◽  
Sw Poland ◽  
Break Up ◽  
Maximum Temperatures ◽  
Early Palaeozoic

AbstractThe pressure–temperature–deformation–time (P–T–d–t) record of metagranitic rocks and adjacent diverse rocks of the metavolcano-sedimentary group from the Orlica–Śnieżnik Dome (OSD) in SW Poland is examined. The study aims to better understand the course of the break-up of northern Gondwana and the overprinting Variscan tectonometamorphism in the NE Bohemian Massif. We test the existing hypotheses that explain the Cambro-Ordovician thermal event recorded in the meta-supracrustal group by (i) syn-deformational regional metamorphism or (ii) the contact metamorphism of the (meta)sedimentary rocks around the intruding ~490–500 Ma granitic magmas. In addition, we check the extent and timing of the Variscan prograde and retrograde medium-pressure metamorphism in the OSD. The results imply that Early Palaeozoic monazites, rarely preserved in both rock groups, document ~490–500 Ma volcanic and plutonic events related to the Gondwana's break-up and following disturbance of the Th–U–Pb system during younger, Variscan events. The monazite geochronology reveals no distinct Cambro-Ordovician thermal aureole around the post-granitic orthogneisses. However, no large-scale Variscan juxtaposition is evident between the two main OSD rock groups or within the meta-supracrustal rocks. Consistent P–T–d–t results for the meta-supracrustal rocks and the orthogneisses suggest that their precursors contacted before the Variscan tectonometamorphism. The directly contiguous ortho- and paragneisses together experienced tectonometamorphic processes at maximum depths that correspond to 7.5–8.0 kbar and maximum temperatures of ~600–620°C, as a result of the Variscan collision of Gondwana and Euramerica. The continental collision-related events intensified at ~360 Ma and ~330–340 Ma.

SHRIMP zircon study of a micromonzodiorite dyke in the Karkonosze Granite, Sudetes (SW Poland): age constraints for late Variscan magmatism in Central Europe

2009 ◽  
Vol 147 (1) ◽  
pp. 77-85 ◽  
Author(s):  
MAREK AWDANKIEWICZ ◽  
HONORATA AWDANKIEWICZ ◽  
RYSZARD KRYZA ◽  
NICKOLAY RODIONOV
Keyword(s):  
Central Europe ◽  
Published Data ◽  
Promising Tool ◽  
Regional Tectonic ◽  
Minimum Age ◽  
West Sudetes ◽  
Sw Poland ◽  
Shrimp Zircon Geochronology ◽  
Age Constraints ◽  
Shrimp Zircon

AbstractThe large Variscan Karkonosze Granite in the West Sudetes, representative of the vast Variscan granite plutonism in Central Europe and located adjacent to regional tectonic suture and strike-slip-zones, has been difficult to date precisely; a range of published data varies between c. 304 and 328 Ma. However, the granite is cut by locally numerous lamprophyre and other dykes. Dating of the dyke rocks, emplaced shortly after the granite intrusion and cooled more rapidly, provides a promising tool for the verification of published SHRIMP results on the granite itself. SHRIMP zircon geochronology of a studied micromonzodiorite dyke indicates substantial admixture of inherited zircons of c. 2.0, 1.4 Ga (207Pb–206Pb minimum ages), and c. 570 (and 500?) Ma. The average concordia age of the main magmatic population of the zircons in the dyke is 313 ± 3 Ma (2σ); however, the true magmatic age might be older, around 318 Ma. This would constrain the age of the hypabyssal magmatism in the Karkonosze Massif and the minimum age of the host Karkonosze Granite. Thus, the Karkonosze Granite is confirmed as representative of an early phase of Variscan granite plutonic activity in the central-European Variscides.

Magma genesis in the lithosphere-asnthenosphere boundary during lithosphere break up

2021 ◽  
Author(s):  
Luan Paula ◽  
Rommulo Vieira Conceicao ◽  
Fernanda Gervasoni ◽  
Marcos Thoaldo Romeiro
Keyword(s):  
Magma Genesis ◽  
Break Up
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