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Tytuł:
Pollen-dominated European palynological assemblages from the Permian of NW Turkey (Asia Minor) palaeogeographical context and microfloral affinities
Autorzy:
Stolle, E.
Powiązania:
https://bibliotekanauki.pl/articles/2059158.pdf
Data publikacji:
2011
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Permian
Turkey
Pontides
palynology
pollen
Opis:
Palynological assemblages from the Camdag area of NW Turkey are analysed quantitatively and qualitatively. All preparations logged from different palynomorph sampling sections show high ratios of pollen. Within the pollen fraction percentages of up to 71% for the bisaccate pollen Lueckisporites Potonie and Klaus 1954 are remarkable. This pattern is reminiscent of palynofloras described from the Upper Permian of Europe. This enables the study area to be shown in its palaeogeographic context, and constrains interpretation of microfloral affinities, palynostratigraphy, and depositional environment. The palaeoenvironmental model clearly indicates deposition within the hinterland, corroborating previous interpretations.
Źródło:
Geological Quarterly; 2011, 55, 2; 181-186
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palaeomagnetism of Permian through Early Triassic sequences in central Spitsbergen: contribution to magnetostratigraphy
Autorzy:
Nawrocki, J.
Grabowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059421.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Spitsbergen
Permian-Early
Triassic
magnetostratigraphy
correlation
Opis:
A total of 297 samples for palaeomagnetic studies were collected from Upper Gzhelian through Spathian sediments of the Isfjorden area (central Spitsbergen). In spite of extensive Cenozoic remagnetisation the studied rocks yielded palaeomagnetic poles and magnetostratigraphy. Almost all Permian samples were reversely magnetised during Kiaman superchron. Normal-polarity samples appear in the Ufimian and Kazanian sediments. The topmost samples from the Kapp Starostin Formation (Upper Permian) contain reverse polarity. The magnetic polarity record noted in the Early Triassic (Griesbachian-Spathian) sequences is fully convergent with magnetic polarity schemes obtained in the Canadian Arctic and Deltadalen type section.
Źródło:
Geological Quarterly; 2000, 44, 2; 109-117
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anhydrite and gypsum in the Devonian and Permian evaporite lithofacies of Belarus : a review
Autorzy:
Makhnach, A.
Shimanovich, V.
Streltsova, G.
Mikhajlov, N.
Powiązania:
https://bibliotekanauki.pl/articles/2060068.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
anhydrite
gypsum
evaporites
Devonian
Permian
Belarus
Opis:
Anhydrite is widespread in the Prypiać Trough in the form of beds and nodules in the Subsaliferous Terrigenous and Carbonate formations (Eifelian and Frasnian), the Lower Saliferous Formation (Frasnian), the Intersaliferous and Upper Saliferous formations (Famennian). It is also present in the Asselian and Sakmarian (Lower Permian) deposits of the trough. The anhydrite is grey, blue, pink and orange. It has massive and, more rarely, horizontal bedding, and a fine- and micro-crystalline structure. Gypsum extends widely across the Orša Depression, Žlobin and Latvijas Saddles and partly in the Belarusian Anteclise, where it lies within the Eifelian deposits. It is also found in the Frasnian strata of the North-Prypiać Shoulder. As a component of facial analogue of the Upper Saliferous Formation gypsum forms the Bryniou deposit in the west of the Prypiać Trough. This mineral is also observed in the Oversaliferous Formation (Famennian) and in the Asselian and Sakmarian strata of the trough. There are spar, saccharoidal, alabastrine and selenitic varieties of gypsum. A medium to coarse crystalline structure is typical. The gypsum is grey, pink, yellow or orange.
Źródło:
Geological Quarterly; 2014, 58, 3; 577-590
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bryozoans (trepostomes and fenestellids) in the Zechstein Limestone (Wuchiapingian) of the North Sudetic Basin (SW Poland : palaeoecological implications
Autorzy:
Hara, U.
Słowakiewicz, M.
Raczyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/2060558.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
bryozoans
Late Permian
Zechstein
taxonomy
ecology
Opis:
A recently investigated Zechstein Limestone (Ca1, Wuchiapingian) bryozoan fauna from the Polish part of the Southern Permian Basin (SW Poland) is dominated volumetrically and taxonomically by fenestellids. In total six species from five genera are recognized, comprising two species of trepostomes belonging to Dyscritella Girty, 1911 and four fenestellids attributed to Kingopora Morozova, 1970, Kalvariella Morozova, 1970, Acanthocladia King, 1849 and Spinofenestella Termier and Termier, 1971. The greatest biodiversity of the bryozoans in the Ca1 profiles studied is within the slope facies where large, fan-shaped and funnel-shaped reticulate fenestellid colonies up to 10 cm high dominate. In contrast, bryozoans in the marginal (proximal) parts of the basin mostly comprise trepostomes, represented by encrusting plate-like or coil-shaped colonies of Dyscritella Girty, and commonly broken branched colonies of Acanthocladia King. The changes in the biotic composition of the bryozoans and the presence of a dominant colony growth form in the stratigraphical profile of the Ca1 reflect the depositional environment and water energy. These factors stimulate the successive stages of the development of the biota and their settlement, marked by the rich productid-fenestellid assemblages typical of the offshore setting, with the maximum depth in the middle part of the Ca1 in the Grodziec Syncline. The proximal tempestites and foreshore facies of the upper part of the Ca1 (Leszczyna Syncline) terminate the sedimentary cycle of the Ca1, with the remnant, broken bryozoans of Acanthocladia and fenestellids. The relationship between the taxonomic composition, colony growth-patterns, associated biota, and sedimentary structures points to slow sedimentation rate on slope and basin floor of the Ca1 carbonate platform. The fenestellids which are dominated in the studied biota by the reticulate and pinnate colonies of Spinofenestella, Kingopora, Kalvariella and Acanthocladia mark a close palaeogeographical link with the Zechstein (Ca1) bryozoans of Great Britain, Germany and the southern Baltic region.
Źródło:
Geological Quarterly; 2013, 57, 3; 417--432
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sulphur and oxygen isotope signatures of late Permian Zechstein anhydrites, West Poland: seawater evolution and diagenetic constraints
Autorzy:
Peryt, T. M.
Halas, S.
Petrivna Hryniv, S.
Powiązania:
https://bibliotekanauki.pl/articles/2059022.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Permian
Zechstein
marine evaporites
sulphate isotopes
Opis:
The stable oxygen and sulphur isotope ratios of 52 anhydrite samples from three Zechstein anhydrite units (Lower Anhydrite, Upper Anhydrite and Basal Anhydrite) of West Poland show d18O values vs. VSMOW in the range of 9.4 to 15.5% (mean of 12.6 š1.3%), and d34S values vs. VCDT between 9.6 to 12.6%o (mean of 11.4 š0.6%o). A generally uniform distribution pattern of both isotopic values throughout the section, although with some random variation, implies that sulphate ions were sufficiently supplied and the basin was open during sulphate deposition. There is a slight stratigraphic differentiation of both the d18O and d34S values: the highest mean values are shown by the Upper Anhydrite and the lowest average values occur in the Basal Anhydrite. The correlation between d18 O and 8 S values is statistically significant only in case of the Basal Anhydrite. A wide range of oxygen isotopic ratios (from 11.6 to 25. l%o), with only several samples having d18O values that fall within the range of late Permian seawater, have been recorded in anhydrite cements and nodules that occur in the Main Dolomite rocks. Sulphur isotope ratios of anhydrite cements (range of 7.6 to 12.9%o, average of 10.7 š1.4%o) tend to reflect the late Permian sulphur isotopic signature of sulphate in seawater. The higher ranges of d18O and d34S values of anhydrite cements and nodules in the Main Dolomite compared to the underlying and overlying anhydrites are due to diagenetic resetting. The conversion of gypsum to anhydrite (often very early and under negligible cover) evidently did not affect the primary marine stratigraphic sulphur isotope composition of the sulphate deposits.
Źródło:
Geological Quarterly; 2010, 54, 4; 387-400
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Strontium isotopes in the Zechstein (Upper Permian) anhydrites of Poland: evidence of varied meteoric contributions to marine brines
Autorzy:
Denison, R. E.
Peryt, T. M.
Powiązania:
https://bibliotekanauki.pl/articles/2059197.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Polska
Zechstein
Late Permian
anhydrite
strontium isotopes
Opis:
Strontium isotope ratios have been determined on 74 anhydrite samples from seven borehole cores in the Polish Zechstein. Five of the borehole cores are located in the basin and isotope results from these samples show a nearly pure marine signal. Results from one borehole core, located near the Zechstein coastline that migrated through time, record a stronger, in consistent influence of continental strontium to a marine base. Intermittent meteoric influence is recorded in anhydrites from other borehole cores close to the carbonate platform that was emergent during the anhydrite deposition. Consistency of isotope values indicates a marine signal and there is a narrow range in consistent values from 87Sr/86Sr near deltasw –215 (0.70702) for the oldest anhydrites and near deltasw –205 (0.70712) for the youngest an hydrites. Comparison with a sea water 87Sr/86Sr curve based on samples in West Texas and a Permian-Triassic boundary value from China shows that the Polish Zechstein in these seven boreholes is latest Permian in age and major deposition represents a short time interval (~2 million years). Strontium isotope ratios reported by other workers indicate some of the younger Zechstein elsewhere indicate even greater continental influence is in agreement with the interpreted sedimentological set ing for those anhydrites.
Źródło:
Geological Quarterly; 2009, 53, 2; 159-166
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
What do the K-Ar ages of illite tell us about the diagenesis of Rotliegend sandstones of the Fore-Sudetic Monocline, SW Poland?
Autorzy:
Biernacka, J.
Powiązania:
https://bibliotekanauki.pl/articles/2060296.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
K-Ar dating
illite
sandstone
Permian
Polska
Opis:
The all available K-Ar data of authigenic illite from Rotliegend aeolian sandstones of the Fore-Sudetic Monocline, including the results from six samples examined in the present study, are reviewed in terms of their geological meaning, relation to diagenetic processes occurring in the sandstones, and implications for a petroleum system. The majority of ages fall in the range between 195 and 150 Ma, i.e. they correspond to Jurassic times. The results may be grouped in several time intervals, which are almost identical to those identified for Rotliegend sandstones of central and western Europe, and which are interpreted as pulses of intensive illite growth. The K-Ar data corroborate the long-held assumption that throughout the entire Southern Permian Basin Jurassic illite growth was triggered by the same, large-scale underlying processes, which manifested themselves in enhanced heat flow. These processes may also have caused the expulsion of hydrocarbons from source rocks.
Źródło:
Geological Quarterly; 2015, 59, 2; 257--270
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Discovery of an earliest Triassic, post-extinction foraminiferal assemblage above the Permian-Triassic boundary, Strandzha nappes, north-west Turkey
Autorzy:
Okuyucu, C.
Ivanova, D.
Bedi, Y.
Ergen, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059978.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Permian-Triassic bounday
post extinction
foraminifera
Strandzha
Turkey
Opis:
A new foraminiferal fauna from Early Triassic (Induan) strata of the Çaglayik section on the “Strandzha Massif”, north-west Turkey, comprises five species precisely determined and five species in open nomenclature belonging to ten genera. They belong to the post-extinction foraminiferal assemblage of the Permian-Triassic crisis, characterized by the presence of both disaster taxa (Earlandia and Postcladella kalhori) and Lazarus taxa (Diplosphaerina inaequalis, Rectostipulina quadrata, Arenovidalina sp. and Glomospira sp.). The present study at Tütünlüktepe Formation identified for the first time the Permian foraminifers on the Strandzha Massif as relict members of a post-extinction foraminiferal assemblage.
Źródło:
Geological Quarterly; 2014, 58, 1; 117--24
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The first microfossil record of ichthyofauna from the Naujoji Akmenė Formation (Lopingian), Karpėnai Quarry, northern Lithuania
Autorzy:
Dankina, D.
Chahud, A.
Radzevičius, S.
Spiridonov, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060600.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
chondrichthyans
actinopterygians
Upper Permian
Zechstein Basin
northern Lithuania
Opis:
The assemblage of rare fish microremains of chondrichthyans and actinopterygians from Upper Permian deposits in Karpénai Quarry in northern Lithuania is described in detail for the first time. The deposits are characterized as reflecting a rapid phase of deposition of the Zechstein Limestone, interpreted as on a shallow shelf above storm-wave base in a proximal part of the Polish-Lithuanian Zechstein Basin. The actinopterygian microremains are represented by various teeth and a few scales from mostly palaeonisciforms and pycnodontiforms. The chondrichthyans are represented by various eusela- chian-type scales and a tooth of ?Helodus sp. The low abundance and low species diversity of the fossil assemblages studied may be due to arid palaeoenvironments that caused locally restricted conditions at this palaeogeographical location.
Źródło:
Geological Quarterly; 2017, 61, 3; 602--610
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Muszloraczkowa stratygrafia pogranicza permu i triasu : rzeczywistość czy mit?
Conchostracan stratigraphy of the Permian/Triassic boundary interval : reality or myth?
Autorzy:
Becker, A.
Powiązania:
https://bibliotekanauki.pl/articles/2075130.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Permian/Triassic boundary
conchostracans
stratigraphy
perm
trias
muszloraczki
stratygrafia
Opis:
In the last years, the conchostracan stratigraphy has become a popular method for distingushing the Permian/Triassic boundary in intracontinental settings. This paper provides a background of chronostratigraphic interpretation of the new method. Several problems are reported, from which the most important are: 1 – lack of consequent documentation of the index species, 2 – indirect correlation with the conodont stratigraphy through the sporomorph spectra, 3 – lack of definition and documentation of supporting palynologic zones, 4 – difficulties in taxonomic determinations of conchostracan. Revision of the method by several independent research teams is suggested.
Źródło:
Przegląd Geologiczny; 2014, 62, 4; 184--189
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbon isotope stratigraphy of the basal Zechstein (Lopingian) strata in Northern Poland and its global correlation
Autorzy:
Peryt, T. M.
Durakiewicz, T.
Kotarba, M. J.
Oszczepalski, S.
Peryt, D.
Powiązania:
https://bibliotekanauki.pl/articles/2058984.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Upper Permian
Zechstein
organic geochemistry
Kupferschiefer
carbon isotope stratigraphy
Opis:
The Kupferschiefer (T1) records a period of basin-wide euxinic conditions, and is thus considered an excellent time-marker in the Zechstein (Lopingian) basin. Previous studies indicated that both the Kupferschiefer and Marl Slate and the overlying Zechstein Limestone (Magnesian Limestone) show remarkable changes in carbon isotopic composition towards higher 131313131313
Źródło:
Geological Quarterly; 2012, 56, 2; 285-298
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The sulphur and oxygen isotopic composition of anhydrite from the Upper Pechora Basin (Russia) : new data in the context of the evolution of the sulphur isotopic record of Permian evaporites
Autorzy:
Galamay, A. R.
Meng, F.
Bukowski, K.
Ni, P.
Shanina, S. N.
Ignatovich, O. O.
Powiązania:
https://bibliotekanauki.pl/articles/2060517.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Upper Pechora Basin
Permian
isotopic composition
anhydrite
pyrite
sulphate reduction
Opis:
This study describes a new determination of the S and O isotope composition of Lower Permian (Kungurian) anhydrites from the Upper Pechora Basin, Cis-Ural region, Russia. δ34S values in sulphate facies vary from +13.7 to +15.1‰; and δ18O values range from +9.3 to +10.4‰. The values of d34S and d18O of anhydrite from halite facies varies from +12.6 to +15.0‰ and +7.5 to +10.9‰ respectively. The quantitative ratio of pyrite content from the water-insoluble residue (silty-sand fraction) is characterized by extremely low (<<1%) to high (4–5%) steep gradation values. The increased presence of pyrite indicates the influence of bacterial sulphate reduction. The sulphate reduction process was more intense, especially when evaporites were formed in mud. The narrow fluctuation range of sulphur and oxygen isotopes values of the measured anhydrite indicates low levels of fractionation. It was established that during the Permian, evolutionary changes in the content of sulphate ions in sea water correlate with the sulphur isotopic composition of marine evaporites
Źródło:
Geological Quarterly; 2016, 60, 4; 990--999
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal maturity and depositional environments of organic matter in the post-Variscan succession of the Holy Cross Mountains
Autorzy:
Marynowski, L.
Salamon, R.
Narkiewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059919.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Permian
Triassic
biomarkers
depositional environment
thermal maturity
Opis:
The results of GC-MS investigations of biomarkers in organic matter from the epicontinental Permian and Triassic strata of the Holy Cross Mts. indicate generally suboxic (Permian) and oxic (Triassic, except for the Middle Muschelkalk) depositional environments with accompanying intensive bacterial reworking of organic remains. The biomarker spectra found in the Middle Muschelkalk and in the Entolium discites Beds (Upper Muschelkalk) show the presence of gammacerane, an increased concentration of C34 homohopanes and a Pr/Ph ratio not exceeding 1. All these observations suggest a hypersaline sedimentary environment with water column stratification and poorly oxygenated conditions. Thermal maturity investigations were based on both vitrinite reflectance and biomarker indices. The organic matter in the Triassic succession is slightly more mature along the northern margin of the Holy Cross Mts. than along their southern part, due probably to a regional increase in the maximum burial depth during the Mesozoic. The maturity of the Permian strata at Gałęzice (southern Holy Cross Mts.) is similar to that of the Triassic rocks whereas Kajetanów (in the north) is characterised by values significantly higher and comparable to those found in wells further north. The difference cannot be accounted for solely by differential burial depths, and implies the existence of a positive thermal anomaly active before the Middle Triassic. Our investigations generally confirmed the low thermal maturity of the Triassic. However, contrary to earlier interpretations, we suggest that the maximum burial depths based on a reconstructed thickness of the post-Triassic deposits may account for the observed maturity levels, assuming that geothermal gradients in the Mesozoic were similar to today's.
Źródło:
Geological Quarterly; 2002, 46, 1; 25-36
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Foraminiferal colonization related to the Zechstein (Lopingian) transgression in the western part of the Wolsztyn Palaeo-Ridge area, Western Poland
Autorzy:
Peryt, D.
Peryt, T. M.
Raczyński, P.
Chłódek, K.
Powiązania:
https://bibliotekanauki.pl/articles/2059413.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Upper Permian
Zechstein
encrusting foraminifers
carbon isotopes
oxygen isotopes
transgression
breccias
Opis:
The basal Zechstein succession in SW Poland is dominated by breccias and/or conglomerates or extraclast-bearing bioclastic limestones, which were deposited during rapid flooding of the pre-existing intracontinental basin in the early Lopingian (Late Permian). Of these, the boulder-cobble breccias and conglomerates are interpreted as deposited in a rocky shore-zone where density flows and upwelling prevailed. The breccias gradually pass up into bryozoan (or other bioclastics) grainstones. The matrix-supported breccias were deposited as large extraclasts and blocks of Carboniferous rock were rolled down or detached from a cliff and were then either embedded into a carbonate sand or formed a framework supplying voids that could be colonized by tubular encrusting foraminifers. These foraminifers abound in all basal Zechstein facies (except in the debris-flow deposits) and are attributed to Palaeonubecularia. The associated faunas include other foraminifers (uniserial and hemigordiopsids), bryozoans, brachiopods, bivalves, gastropods, and microbial deposits. The prolific growth of tubular encrusting foraminifers has resulted from nutrient supply from the basin by upwelling. Botryoidal aragonite cements (also interpreted as due to upwelling) also characterize the basal Zechstein strata, although they were previously reported only from the upper Zechstein Limestone. The ẟI3C values of the basal Zechstein deposits show small variation and oscillated around 4.0%o, suggesting that these deposits are younger than the Kupferschiefer.
Źródło:
Geological Quarterly; 2012, 56, 3; 529--546
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sand sheets interaction with aeolian dune, alluvial and marginal playa beds in Late Permian Upper Rotliegend setting (western part of the Poznań Basin, Poland)
Autorzy:
Kiersnowski, H.
Buniak, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060530.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Upper Rotliegend
sand sheet
marginal playa
Poznań Basin
Polska
Late Permian climate
Opis:
The Upper Rotliegend deposits of the western part of the Poznań Basin, Poland, represent three main sedimentary environments: aeolian desert (dunes and sand sheets), alluvial plain (alluvial covers with wadi deposits) and marginal playa. In arid periods, dunes prograded into areas dominated by alluvial sedimentation. During wet periods, alluvial deposits eroded the aeolian deposits and prograded onto dune fields. Playa sediments were deposited among aeolian or alluvial sediments during periodic expansions of the playa. These aeolian, alluvial and playa deposits are arranged in depositional sequences. Boundaries between sequences are marked by rapid changes in depositional facies; and by erosional bounding surfaces. Maximum Wetting Surfaces have been distinguished within some parts of the depositional sequences, which enable regional correlations. The sections studied are composed of thick sequences of sand and sand-gravel sheets. The sand sheets represent periods of stratigraphic condensation. Systems of sand sheets are typical of marginal areas of ergs. We distinguish nine depositional complexes (units) numbered 1-9 from base to top, respectively. These subdivisions are based on the interpretation of the sedimentological record in palaeoclimatic terms, and in terms of major erosional boundaries, which are probably of regional extent. In the aeolian deposits, major boundaries are associated with deflation surfaces related to the stabilization of groundwater levels. In the marginal playa deposits, the most important boundaries are correlated to transgressive surfaces that developed during playa expansion. Time gaps represented by the boundaries and the scale of erosion below them, are difficult to estimate. The depositional system of the Upper Rotliegend was dominated by sand and sand-gravel sheets, and is either a unique feature in the entire Southern Permian Basin or, as we assume, sand sheets occur more com monly in the Rotliegend than has been previously thought.
Źródło:
Geological Quarterly; 2016, 60, 4; 771--800
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 38

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