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Source rocks for heavy minerals in lower part of Menilite Formation of Skole Nappe (Polish Flysch Carpathians), based on study of detrital garnet and tourmaline

Salata D.

Annales Societatis Geologorum Poloniae

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2013

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Vol. 83, No. 1

1--17

EN

The study focused on the chemistry of detrital garnet and tourmaline from sediments of the Boryslav and Kliva Sandstone types in the Oligocene part of the Menilite Formation of the Skole Nappe (Western Outer Carpathians, Poland), with regard to provenance. Almandine and almandine-pyrope compositional varieties are the most common garnets, with minor almandine-pyrope-grossular garnet. Scarce garnet grains, with grossular and spessartine as the dominant end-members, are also present. The tourmaline belongs to the alkali tourmaline principal group and represents the schörl-dravite series. The detrital garnet and tourmaline display strong, compositional similarities to minerals, occurring in igneous and metamorphic rocks of the Bohemian Massif, as well as to detrital grains, deposited within the internal basins of the massif. This suggests that the primary rocks for the garnet and tourmaline may be crystalline complexes of the Bohemian Massif. However, other uplifted areas, similar to the complexes of the Bohemian Massif, cannot be ruled out. Such hypothetical areas could be located in the northern foreland of the Carpathian basins. Euhedral tourmaline and other minerals, occurring in the heavy- mineral assemblages studied, most probably were derived from eroded and presently not exposed, crystalline complexes, originally situated in the Skole Basin foreland or within the basin.

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Garnet provenance in mixed first-cycle and poly-cycle heavy-mineral assemblages of the Ropianka and Menilite formations (Skole Nappe, Polish Flysch Carpathians) : constraints from chemical composition and grain

Salata D.

Annales Societatis Geologorum Poloniae

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2013

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Vol. 83, No. 3

161--177

EN

Garnet in heavy-mineral assemblages, occurring in sandstones of the Campanian–Maastrichtian part of the Ropianka (Late Cretaceous–Palaeocene) and Menilite (Oligocene) formations of the Skole Nappe, is present as first-cycle and poly-cycle grains, derived from a proximal source, remote areas and/or from sedimentary rocks of the Skole Basin foreland. The garnets in the formations are compositionally similar, suggesting an origin from the same source rocks. Relatively large amounts of garnet, represented by euhedral or slightly rounded, weakly etched or unetched almandine and spessartine-almandine garnet, and minor pyrope-enriched almandine, were derived directly from a source close to the Skole Basin. These garnets are from sediments, metamorphosed at low- to medium-grade conditions (such as mica-schists, gneisses) and perhaps also granitic bodies. Rounded and variously etched garnets, especially high pyrope-almandine and pyrope-almandine-grossular varieties, but also partly almandine-dominated varieties, are suggested to have been derived from distant sources, such as sedimentary rocks of the Upper Silesian and Małopolska blocks. Rocks, forming uplifted parts of the crystalline basement of Brunovistulicum and/or crystalline domains of the Bohemian Massif, could have been protoliths for part of the almandine-dominated garnet population, whereas pyrope-grossular-almandine garnets may originate from the granulitic, eclogitic or metabasic rocks of the Bohemian Massif. The study shows that analyses of garnet composition, combined with observations on grain textural features and data on the lithology of clasts and pebbles, can permit the determination of sources for different garnet varieties in mixed-provenance populations.

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Detritus from Variscan lower crust in Rotliegend sandstones of the Intra-Sudetic Basin, SW Poland, revealed by detrital high-pyrope garnet

Biernacka J.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 1

127–-138

EN

It is well established that pebbles in the Sudetic Permian conglomerates were derived from the nearby Variscan massifs of upper-crustal composition. However, the provenance of the sand-size grains remains enigmatic. Electron microprobe analyses (EMPAs) of detrital garnet from upper Rotliegend conglomerates and sandstones exposed at Golińsk, the Intra-Sudetic Basin, showed a distinct assemblage dominated by high-pyrope (high-grossular) almandine, typical of high-grade metamorphic rocks, such as high-pressure granulites. These results, coupled with a previously reported population of similar detrital garnet in the stratigraphically equivalent conglomerates and sandstones of the Karkonosze Piedmont Basin, suggest regional input of detrital lower-crustal material. This detritus was derived ultimately either from the Moldanubian Zone of the Bohemian Massif, or from high-grade rocks of the Orlica-Śnieżnik Massif that were exposed in the Carboniferous–Permian. Permian siliciclastic rocks might have covered a large part of the Sudetes. During the Mesozoic and Palaeogene, these rocks might have been recycled further, contributing high-pyrope garnet, as an accessory mineral, into siliciclastic rocks of the Sudetes and their foreland.

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Detritus from Variscan lower crust in Rotliegend sand stones of the Intra-Sudetic Basin, SW Poland, revealed by detrital high-pyrope garnet

Biernacka J.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 2

127–-138

EN

It is well established that pebbles in the Sudetic Permian conglomerates were derived from the nearby Variscan massifs of upper-crustal composition. However, the provenance of the sand-size grains remains enigmatic. Electron microprobe analyses (EMPAs) of detrital garnet from upper Rotliegend conglomerates and sandstones exposed at Golińsk, the Intra-Sudetic Basin, showed a distinct assemblage dominated by high-pyrope (high-grossular) almandine, typical of high-grade metamorphic rocks, such as high-pressure granulites. These results, coupled with a previously reported population of similar detrital garnet in the stratigraphically equivalent conglomerates and sandstones of the Karkonosze Piedmont Basin, suggest regional input of detrital lower-crustal material. This detritus was derived ultimately either from the Moldanubian Zone of the Bohemian Massif, or from high-grade rocks of the Orlica-Śnieżnik Massif that were exposed in the Carboniferous–Permian. Permian siliciclastic rocks might have covered a large part of the Sudetes. During the Mesozoic and Palaeogene, these rocks might have been recycled further, contributing high-pyrope garnet, as an accessory mineral, into siliciclastic rocks of the Sudetes and their foreland.