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Wyświetlanie 1-5 z 5
Tytuł:
Coastal sandy spit deposits (Lower Burdigalian/Eggenburgian) in the Alpine-Carpathian Foredeep of Lower Austria
Autorzy:
Nehyba, Slavomír
Roetzel, Reinhard
Powiązania:
https://bibliotekanauki.pl/articles/2058681.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Alpine-Carpathian Foredeep
Early Miocene
Eggenburg Bay
coastal spit
provenance analysis
Opis:
In the type-area of the Eggenburgian regional stage (Lower Burdigalian) sands with large-scale clinoforms were studied north-west of Eggenburg (Lower Austria). Stratigraphic and facies architecture, palaeocurrent pattern and inferred palaeogeographic setting show that these sands are deposits of W-E trending and SW to SSE prograding coastal spit systems, attached to crystalline shoals or islets in the shallow marine Eggenburg Bay. The spits were dominantly formed by shoal parallel accretion above fair-weather wave base due to longshore transport. The 4-5 m thick clinoforms with bottomset, foreset and topset structures contain up to 3.6 m thick, steeply inclined foresets, dominated by sediment gravity-flow deposition. Relatively stable depositional conditions, characterized by strong unidirectional currents, high sand supply and sufficient accommodation space are assumed for their formation. However, internal reactivation surfaces indicate variations in current activity, orientation and velocity. The deposits of spit systems are interpreted as part of a transgressive systems tract. The provenance analysis reveals the local Moravian and Moldanubian crystalline rocks as principal source. The spit sands of the Burgschleinitz Formation show the highest mineralogical maturity within the studied Lower Miocene succession. Intense reworking and redeposition of material from older deposits is evident. Due to the ongoing transgression deposits of the following Gauderndorf Formation and Zogelsdorf Formation exhibit a larger catchment area with input of high amounts of fresh weathered material.
Źródło:
Geological Quarterly; 2021, 65, 4; 40--70
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stacked Gilbert-type deltas filling an incised palaeovalley along the cratonward margin of a foreland basin (Miocene, Western Carpathian Foredeep)
Autorzy:
Nehyba, Slavomír
Powiązania:
https://bibliotekanauki.pl/articles/2201216.pdf
Data publikacji:
2022
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Western Carpathian Foredeep
incised valley
Gilbert-type deltas
stratigraphic architecture
provenance analysis
Opis:
The coarse-grained Brno sands are an important groundwater aquifer and represent a volumetrically significant component of the Lower Badenian/Middle Miocene sedimentary infill of the Western Carpathian Foredeep, a foreland basin formed on the eastern margin of the Bohemian Massif in front of the Western Carpathians. The integration of core and outcrop facies analysis, summary of facies features, depositional processes and architectures, and integration of provenance analysis have led to a new depositional model for the Brno sands as the product of Gilbert-type delta systems prograding into an incised palaeovalley developed on the outer foreland basin margin. The position, shape and morphology of the palaeovalley were influenced by pre-Neogene basement faults trending NW–SE. The Gilbert-type deltas recognized can be classified as foreset-dominated with other elements subordinate. The foreset beds mainly reflect low-density turbidites, with varied but important evidence of deposits of high-density turbidity currents, cohesionless debris flows and debris falls. The thick foreset deposits show, in detail, repetitive successive prograding-retrograding episodes. These are interpreted as rapid high-frequency pulses of relative sea level change i.e. as high-frequency depositional sequences. The deltaic deposition of the Brno sands was terminated by deposits of a shoal-water delta and the sands were finally drowned by a thick pile of offshore pelagic clays. The provenance of Brno sands is located into the nearby geological units. Redeposition from the older basin infill also played an important role.
Źródło:
Geological Quarterly; 2022, 66, 3; art. no. 28
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-energy, microtidal nearshore deposits and their provenance (Lower Miocene, Burdigalian/Eggenburgian, Alpine-Carpathian Foredeep, Lower Austria)
Autorzy:
Nehyba, Slavomír
Roetzel, Reinhard
Powiązania:
https://bibliotekanauki.pl/articles/2201202.pdf
Data publikacji:
2022
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Alpine-Carpathian Foredeep
Lower Miocene
provenance analysis
fair-weather vs. storm processes
rock shoreline
coastal morphology
Opis:
During the Early Miocene (Early Burdigalian/Eggenburgian) marine transgression at the southeastern margin of the Bohemian Massif, gradual flooding occurred along a rocky coast on granitic bedrock of the Thaya Batholith under high-energy, wave-dominated, microtidal and mixed fair-weather and storm conditions. Deposits of the Burgschleinitz Formation overlie a basal unconformity above a subaerial weathered basement surface (transgressive erosional surface) and are interpreted as a transgressive systems tract. The deposits can be divided into four facies associations/depositional environments, i.e., upper-shoreface, foreshore, gravelly beach and backshore/lagoon. Two stages of transgression and successive overtopping of the basement, with different coastal physiographies, were documented. During the initial stage of transgression a barrier island system developed with relatively fine-grained deposits, reflecting the flooding of the distant parts of the Thaya Batholith with a relative flat basement morphology. The subsequent continuation of the transgression led to the flooding of the more proximal parts of the Thaya Batholith with a steeper relief and formation of a rocky shoreline with deposition of gravelly sedi- ments along palaeo-sea cliffs or wave-cut platforms. While gravel clasts of the deposits investigated originate directly from the underlying granites of the Thaya Batholith, provenance studies show that metamorphic rocks of the Moravian Superunit in the hinterland were the main source of sands. This distant source material was probably delivered mainly by small creeks and alluvial fans to the nearshore. Significant differences in heavy mineral composition of the same formation in the wider vi cinity indicate primarily local sources and rapid deposition with subordinate longshore transport, which may reflect a complex coastal palaeogeography. The Lower Miocene deposits of the Burgschleinitz Formation investigated are a rare example of ancient rocky shore deposits, which generally have low preservation potential in the geological record.
Źródło:
Geological Quarterly; 2022, 66, 4; art. 66, no. 33
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of a sedimentary infill of a palaeovalley at a distal margin of the peripheral foreland basin
Autorzy:
Nehyba, Slavomír
Gilíková, Helena
Tomanová-Petrová, Pavla
Otava, Jiří
Skácelová, Zuzana
Powiązania:
https://bibliotekanauki.pl/articles/2058674.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
peripheral foreland basin
Neogene
forebulge
confined valley
facies analysis
provenance study
Opis:
The entrenched Odra palaeovalley, cut into the bedrock of the distal margin (forebulge basal unconformity) of the Moravian Carpathian Foredeep (peripheral foreland basin) is filled with an almost 300 m thick pile of Miocene deposits. The directon of the valley (NW-SE to NNW-SSE) has been controlled by faults subparallel with the system of “sudetic faults“. The sedimentary succession consists of 5 facies associations/depositional environments, which are interpreted (from bottom to top, i.e. from the oldest to the youngest) as: 1 - colluvial deposits to deposits of alluvial fan, 2 - deposits of alluvial fan, 3 - fan-delta deposits, 4 - shallow water delta to nearshore deposits and 5 - open marine deposits. This fining-up and deepening-up succession reveals the following: the formation of the new flexural shape of the basin; deep erosion connected with uplift and tilting of the forebulge and reactivation of the NW-SE trending basement faults; the Early/Middle Miocene sea level fall; alluvial deposition mostly driven by tectonics and morphology; forebulge flexural retreat; Middle-Miocene sea level rise; back-stepping of valley infill; marine invasion during the Early Badenian with shift of the coastline further landward of the pallaeovalley. Tectonics related to contemporary thrusting processes in the Western Carpathians are assumed to be the dominating factor of the studied deposition at the expense of eustatic sea level changes. Provenance studies have proven that the pre-Neogene basement (i.e. the Early Carboniferous clastic “Culmian facies” ofthe Moravian-Silesian Paleozoic) represents an important source for the conglomerates and sands, which volumetrically dominate in the palaeovalley infill. However, they also showed, that the deposits of the earlier Carpathian Foredeep Basin sedimentary stage (Karpatian in age?) covered the area under study and were eroded and resedimented into the palaeovalley infill.
Źródło:
Geological Quarterly; 2019, 63, 2; 319--344
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
REE-bearing minerals in sediment-hosted stratiform pyrite mineralization zones of the Wiśniówka area (Holy Cross Mts., Poland)
Autorzy:
Migaszewski, Zdzisław M.
Gałuszka, Agnieszka
Zielińśki, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/31342963.pdf
Data publikacji:
2023
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
siliciclastic rocks
REE-bearing minerals
geochemical analysis
SEM-EDS
EMPA
REE-mineral provenance
Wiśniówka area
Polska
Opis:
There are two arsenical pyrite (As-FeS2mineralization zones cropping out in the Podwiśniówka and Wiśniówka Duża quarries where quartzites and quartzitic sandstones have been extracted for over a century. A large amount of pyrite in the Wiśniówka siliciclastics is unusual in the hard rock mining throughout the world. The pyritiferous beds contain a variety of REE-bearing minerals, including a crandallite series of aluminum-phosphate-sulfate (APS) minerals, e.g., predominant goyazite SrHAl3[(PO4)2(OH)6] with subordinate gorceixite BaHAl3[(PO4)2(OH)6] and very occasional crandallite CaHAl3[(PO4)2(OH)6]. By contrast, the other REE-phosphate minerals, e.g., xenotime YPO4, bur particularly monazite CePO4 occur in a lesser amount. Goyazite prevails somewhat in the Podwiśniówka beds whereas xenotime in the Wiśniówka Duża beds. Of the other REE-bearing minerals, bastnäsite REECO3(F,OH), florencite (REE)Al3(PO4)2(OH)6 and synchysite CaCe[CO3]2F occur in trace amounts. Interestingly, the quite common phosphate minerals, i.e., wavellite (Al.3[(OH,F)3|(PO4)2]×5H2O and variscite Al[PO4]×2H2O) are depleted in REEs with only Ce attaining 0.09 wt.% as documented by an electron-probe microanalysis. In contrast to quartzites/quartzitic sandstones, carbonaceous clayey-silty shales and bentonites/tuffites are distinctly enriched in REE-bearing minerals. This diversity is also mirrored in the mean total REE concentrations varying from 204 to 314 mg/kg, in clayey-silty shales and bentonites, attaining 457 mg/kg in some Podwiśniówka shale beds. Results of this and the previous petrographic, mineralogical and geochemical studies have indicated that REE-bearing minerals formed generally along with As-rich pyrite, nacrite/dickite and probably TiO2 polymorphs as a result of multiphase hydrothermal vent activity that took place in the Wiśniówka Late Cambrian sedimentary basin. This evidence is also backed up by the values of LREENASC/HREENASC (1.44–1.75) and Eu/EuNASC (1.24–1.30) coefficients in the clayey-silty shales. This positive Eu anomaly (31.20) points to the formation of REE-bearing minerals in a reducing environment.
Źródło:
Geological Quarterly; 2023, 67, 2; art. no. 17
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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