High (ultrahigh) pressure metamorphic terrane rocks as the source of the detrital garnets from the Middle Jurassic sands and sandstones of the Cracow Region (Cracow- Wieluń Upland, Poland)

The Middle Jurassic (Upper Bathonian/Lower Callovian) sands and sandstones of the Cracow–Wieluń Upland contain detrital garnets with high contents of the pyrope molecule (30–73 mol %). The predominance of detrital pyrope garnets, and inclusions represented mainly by omphacite and kyanite, show that the garnets were derived from high (ultrahigh) pressure (H/UHP) metamorphic terrane rocks (garnet peridotites, eclogites and granulites). Their source is unknown. The Moldanubian Zone of the Bohemian Massif is closely comparable. However, the terranes between this zone and the Cracow–Wieluń Upland are dominated by almandine garnets. The relatively low proportion of almandine garnets in the examined samples indicates that transport of the detrital material could not have been from a far distant source as the garnet assemblage would otherwise be strongly dominated by almandine. A less distant possible source could have been the Góry Sowie Mts., which incorporate UHP/HP metamorphic rocks, but the exposed areal extent of these rocks is too small. It is possible that larger portions of these metamorphic rocks are buried beneath the Cenozoic cover and might have earlier represented a larger source area. Reworking of the entire heavy mineral spectra from older clastics is improbable because of the low maturity of the heavy mineral assemblages (higher proportion of less stable minerals). The source area therefore remains unknown. Most probably it was formed by primary crystalline complexes of lower crust to mantle origin, outcrops of which were not far distant from the area of deposition. Similar detrital garnet compositions were also recorded in the Outer Western Carpathians (Flysch Zone, Pieniny Klippen Belt), i.e. the crustal segments which formed the Silesian and Magura cordilleras; the Czorsztyn Swell was also formed by similar rocks

Zagadkowy, wysokopiropowy detrytyczny granat w środkowojurajskich utworach klastycznych regionu krakowskiego

W celu rozpoznania składu minerałów ciężkich środkowojurajskich piasków i piaskowców, analizie poddano utwory tego wieku z kilku odsłonięć okolic Krakowa (Dębnik, Dębnik-Czatkowice, Racławice, Paczółtowice). Wykazano w ich obrębie wysoki udział minerałów z grupy granatu, wskazując na duże podobieństwo do minerałów tego typu znanych z zewnętrznych Karpat Zachodnich.Tym niemniej bezpośrednie wskazanie obszaru źródłowego tych minerałów nie jest możliwe, a stwierdzić można jedynie, że ten enigmatyczny region obfitował w granulity, eklogity i perydotyty

Geochemistry of amphibolites and related graphitic gneisses from the Suchý and Malá Magura Mountains (central Western Carpathians) – evidence for relics of the Variscan ophiolite complex

Three small bodies of amphibolites and associated graphitic gneisses from the Suchý and Malá Magura Mountains (Tatric Megaunit, central Western Carpathians) have been studied by petrographic and geochemical methods. Isolated, fault-bounded bodies first hundreds of meters in size are located in the complex of the Early Paleozoic paragneisses and migmatites intruded by the Lower Carboniferous granitoid rocks. Amphibolites (locally actinolite schists) were formed from effusive basalts, dolerites or isotropic gabbros hydrothermally altered and veined before the regional metamorphic transformation. Distribution of the trace elements relatively immobile during the metamorphic alteration (HFSE, REE, Cr, V, Sc) is similar to E-MORB type in the Malá Magura Mountain or to N-MORB/E-MORB types in the Suchý Mountain. Graphitic gneisses to metacherts are rich in silica (up to 88 wt. %) and Ctot, poor in other major element contents and display negative Ce-anomaly, enrichment in HREE, V, Cr and U. They were probably originally deposited as non-carbonate and silica-rich deep-sea sediments in anoxic conditions. The oceanic provenance of amphibolites and related graphitic gneisses clearly indicates their oceanic crust affinity and identity with the uppermost part of the ophiolite sequence. Ophiolite bodies from the Suchý and Malá Magura Mountains are supposed to be relic fault blocks identical with the Upper Devonian Pernek Group which represents a Variscan ophiolite nappe preserved to large extent in the Malé Karpaty Mountains located in the Tatric Megaunit further to the southwest. All these ophiolite relics are vestiges of the original ophiolite suture created by oceanic closure in the Lower Carboniferous

Provenance of synorogenic deposits of the Upper Cretaceous–Lower Palaeogene Jarmuta–Proč Formation (Pieniny Klippen Belt, Western Carpathians)

The Pieniny Klippen Belt contains thickening and coarsening upwards synorogenic sedimentary successions witnessing the collision of the Oravic ribbon continent with the Central Carpathian orogenic wedge after the closure of the Vahic Ocean in the Late Cretaceous to Early Palaeogene. The sedimentary record of this event is represented by flysch/wildflysch deposits of the Maastrichtian–Lower/Middle Eocene Jarmuta–Proč Formation. We present results of the provenance study of these deposits, based on the framework petrography, heavy mineral analysis and mineral chemistry. Turbiditic sandstones were classified as quarzolithic to lithic arenites. Lithic fragments are predominantly composed of carbonate rocks and low- to medium-grade metamorphic and occasional mafic volcanic rocks. The heavy mineral association is composed of both first-cycle derived and recycled ultrastable ZTR, garnets and Cr-spinels. The chemistry of the detrital tourmalines and garnets suggests a derivation from various low- to medium-grade metamorphic rocks. High-pyrope garnets, observed in the eastern part of the PKB, which were derived from high-grade granulites and eclogites, represent probably lower crustal complexes exhumed during rifting of the Vahic Ocean. The Cr-spinels show a mixed harzburgitic and lherzolitic provenance. The harzburgitic Cr-spinels might have been recycled from older exotic conglomerates of the Klape Flysch, thereby representing ophiolitic detritus of the Meliata Ocean. The lherzolitic Cr-spinels might represent a new contribution of ophiolitic detritus delivered from the exhumed subcontinental mantle forming the Vahic oceanic floor