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Trace fossils and depositional environments of the middle Turonian sandstones in the Upper Nysa Kłodzka Graben (Sudetes, Poland) revisited

Chrząstek Alina, Nowicka Nadia

Geological Quarterly

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2021

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Vol. 65, No. 1

art. no. 10

EN

We provide the first reports of some rare trace fossils from the middle Turonian (Upper Cretaceous) of the Sudety Mountains (SW Poland, Upper Nysa Kłodzka Graben, Długopole Górne Quarry). These include burrows ?Ancorichnus isp., Asterosoma cf. ludwigae Schlirf, 2000, Asterosoma isp., cf. Phycodes isp., Dactyloidites ottoi (Geinitz, 1849), Funalichnus strangulatus (Fritsch, 1883), Phycodes cf. palmatus (Hall, 1852), cf. Phycodes isp., Phycosiphon incertum Fischer-Ooster, 1858, ?Phycosiphon isp., Planolites beverleyensis (Billings, 1862) and borings Entobia isp. Some body fossils, bivalves ?Brachidontes sp., Lima canalifera Goldfuss, 1836, Pinna (Pinna) cretacea (Schlotheim, 1813) and Rhynchostreon suborbiculatum (Lamarck, 1801) are also reported. The trace fossil assemblage indicates a distal Skolithos ichnofacies and proximal Cruziana ichnofacies, which characterize a proximal and distal lower shoreface setting respectively. Sedimentation of the middle Turonian sandstones took place in a shallow epicontinental sea of normal salinity and a soft substrate, which was well-oxygenated under low-moderate hydrodynamic conditions. The presence of the oyster Rhynchostreon in the deposits studied suggests the influence of a warm Tethys Ocean.

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Understanding reservoir heterogeneity using variography and data analysis: an example from coastal swamp deposits, Niger Delta Basin (Nigeria)

Obi Ifeanyichukwu S., Onuoha K. Mosto, Obilaja Olusegun T., Dim C. I. Princeton

Geologos

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2020

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Vol. 26, No. 3

207--218

EN

For efficient reservoir management and long-term field development strategies, most geologists and asset managers pay special attention to reservoir chance of success. To minimise this uncertainty, a good understanding of reservoir presence and adequacy is required for better ranking of infill opportunities and optimal well placement. This can be quite challenging due to insufficient data and complexities that are typically associated with areas with compounded tectonostratigraphic framework. For the present paper, data analysis and variography were used firstly to examine possible geological factors that determine directions in which reservoirs show minimum heterogeneity for both discrete and continuous properties; secondly, to determine the maximum range and degree of variability of key reservoir petrophysical properties from the variogram, and thirdly, to highlight possible geological controls on reservoir distribution trends as well as areas with optimal reservoir quality. Discrete properties evaluated were lithology and genetic units, while continuous properties examined were porosity and net-to-gross (NtG). From the variogram analysis, the sandy lithology shows minimum heterogeneity in east-west (E–W) and north-south (N–S) directions, for Upper Shoreface Sands (USF) and Fluvial/Tidal Channel Sands (FCX/TCS), respectively. Porosity and NtG both show the least heterogeneity in the E–W axis for reservoirs belonging to both Upper Shoreface and Fluvial Channel environments with porosity showing a slightly higher range than NtG. The vertical ranges for both continuous properties did not show a clear trend. The Sequential Indicator Simulation (SIS) and Object modelling algorithm were used for modelling the discrete properties, while Sequential Gaussian Simulation (SGS) was used for modelling of the continuous properties. Results from this exercise show that depositional environment, sediment provenance, topographical slope, sub-regional structural trends, shoreline orientation and longshore currents, could have significant impacts on reservoir spatial distribution and property trends. This understanding could be applied in reservoir prediction and for generating stochastic estimates of petrophysical properties for nearby exploration assets of similar depositional environments.

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Coniacian sandstones from the North Sudetic Synclinorium revisited: palaeoenvironmental and palaeogeographical reconstructions based on trace fossil analysis and associated body fossils

Chrząstek A., Wypych M.

Geologos

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2018

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Vol. 24, No. 1

29--53

EN

The Coniacian quartz sandstones (Żerkowice Member, Rakowice Wielkie Formation) that crop out at quarries near Czaple-Nowa Wieś Grodziska (North Sudetic Synclinorium) contain a low-diversity assemblage of trace fossils: Gyrochorte isp., Ophiomorpha nodosa Lundgren, 1891, Ophiomorpha isp., Phycodes cf. curvipalmatum (Pollard, 1981), ?Phycodes isp., Planolites cf. beverleyensis (Billings, 1862), Thalassinoides paradoxicus Woodward, 1830 and ?Thalassinoides isp. Moreover, interesting compound burrow systems, here referred to as Thalassinoides-Phycodes cf. palmatus and ?Thalassinoides-Phycodes, were recognised at the Czaple Quarry. Additionally, ?Gyrochorte isp., Phycodes cf. flabellum (Miller and Dyer, 1878) and ?Treptichnus isp. were encountered at correlative levels in the Rakowice Małe Quarry. Some of these ichnotaxa have not been recorded previously from Coniacian sandstones of the Żerkowice Member. Additionally, in slabs of these sandstones, the gastropod Nerinea bicincta Bronn, 1836 and the bivalve Lima haidingeri Zittel, 1866 were found. These interesting finds, in particular the gastropods, were already noted from the study area in the first half of the twentieth century by Scupin (1912–1913). Ethologically, the trace fossil assemblage is represented by domichnia or domichnia/fodinichnia (Ophiomorpha, Thalassinoides), fodinichnia (Phycodes) and pascichnia (Gyrochorte, Planolites). The compound burrow systems (Thalassinoides-Phycodes) are interpreted as dwelling/feeding structures. The possible tracemakers are crustaceans (Ophiomorpha, Thalassinoides) or worm-like animals (annelids and other) (Planolites, ?Phycodes, Gyrochorte and ?Treptichnus). The assemblage of trace fossils is characteristic of the Skolithos ichnofacies and Cruziana ichnofacies, typical of shallow-marine settings. Ichnological studies, as well as the presence of accompanying fossils (bivalves, gastropods), confirm the palaeoenvironmental reconstruction of the Żerkowice Member sandstones by Leszczyński (2010). That author interpreted the Coniacian sandstones as bar and storm deposits laid down in a shallow epicontinental sea (mainly the foreshore-upper shoreface; up to the middle shoreface) under normal oxygenation and salinity, in soft substrate, above fair-weather wave base. The deposition of the Żerkowice Member sandstones is linked to a regression that started after uplift of the southeastern part of the North Sudetic Synclinorium.

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Sedimentary environment and palaeogeography of the ?Palaeocene-Middle Eocene Kashkan Formation, Zagros fold-thrust belt, SW Iran

Yeganeh Bizhan Yousefi, Feiznia Sadat, Loon A. J. (Tom)

Geologos

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2012

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Vol. 18, No. 1

13--36

EN

The Kashkan Formation (?Palaeocene to Middle Eocene) in the Zagros fold-thrust belt, SW Iran, which is intercalated between to marine limestone formations, consists of conglomerates, sandstones and siltstones. The sedimentology and the palaeogeography of the Kashkan Formation had not received any attention thus far, but have now been studied in seven sections, situated in the province of Lorestan. The sediments form twelve lithofacies, three ichnosubfacies and seven architectural elements, which are described, depicted and analysed. The analysis leads to the conclusion that most sediments accumulated in a low-sinuosity, low-gradient braided-river system (characterised by mainly unidirectional palaeocurrent directions, and by sheetfloods), that occasionally showed meandering characteristics (represented by overbank deposits and large bars). The deposits of this system closely resemble those of the South Saskatchewan River in Canada, which is considered as the classical example of a sand-bed braided river. The river flowed roughly from North to South, as deduced by palaeocurrent indicators such as imbrication and large- to medium-scale trough cross-stratification (direction measured in the trough axes). This current direction is supported by the southward to south-westward thinning of the formation and by the diminishing average grain size in the same direction. The trace fossils in the Kashban Formation fit all in the Skoyenia ichnofacies, which has here three ichnosubfacies which allow a more detailed palaeoenvironmental reconstruction, indicating that the braided stream passed into the low-energy shoreface zone of a tidally-influenced sea.

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Middle Miocene deposits in Carpathian Foredeep : facies analysis and implications for hydrocarbon reservoir prospecting

Lis P., Wysocka A.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 3

239–-253

EN

This sedimentological study was based on well cores from the Polish and Ukrainian parts of the Carpa- thian Foredeep. It revealed general heterogeneity of facies in the middle Miocene of the sedimentary succession in the basin. Fourteen sedimentary facies were distinguished and their origin was interpreted: massive, non-graded sandstones; normal-graded, massive sandstones, with and without a stratified uppermost part; hydroplastically deformed sandstones; planar-parallel-stratified sandstones; trough-cross-stratified sandstones; ripple-cross-lami- nated sandstones; heterolithic deposits, composed of thinly interlayered sandstone and mudstone; massive and laminated mudstones; and basal gypsum/anhydrite evaporites, often intercalated with mudstone. Four main modalities of vertical facies organization were recognized and attributed to the following environments: (1) the mid-late Badenian, shoal-water, evaporitic environment that preceded the latest Badenian–early Sarmatian, main phase of foredeep development; (2) a littoral, tidal environment of the inner parts of storm-influenced, coastal bays and tidal flats or possibly spit-sheltered lagoons; (3) a wave-dominated, littoral, sandy environment, considered to be shoreface, extended by waves, in front of advancing deltas; and (4) a neritic to subneritic, muddy, offshore slope, characterized by frequent incursions of tempestite and turbidite sand. The study contributed to a better understanding of the mid-Miocene depositional systems in the basin, with significant implications for ongoing hydrocarbon exploration. Interpretations of the origins of potential reservoir sandstones provided important information on their possible stratigraphic distribution in the basin fill. The potential, economic importance of stratigraphic hydrocarbon traps underscored the urgent need for a full-scale facies analysis and fully cored wells in strategic parts of the basin.

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Sedimentary environments of the Middle Jurassic epicontinental deposits from the central part of the Polish Basin (Kuiavian Region)

Feldman-Olszewska A.

Volumina Jurassica

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2006

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Vol. 4, no. 1

86-86

EN

The Polish Basin was the eastern part of the Jurassic European epicontinental basin. The zone of maximum thickness of the Middle Jurassic deposits runs along the so called Mid-Polish Trough which extends from the West Pomerania (NW) to the Holy Cross Mountains (SE), generally along the Teisseyre-Tornquist Zone. The complete litological profile of the Middle Jurassic deposits exceeds 1100 m in the depocentre of the Mid-Polish Trough (in the Kuiavian Region). Sediments are represented by sandstones, mudstones, heteroliths and claystones with intercalations of siderites, dolomites and coquina beds. Subordinately, crinoidal limestones, arenaceous limestones, gaizes and oolitic ironstones occur. Sedimentological studies were based on investigation of cores from ten deep boreholes. Nineteen lithofacies were distinguished: black shales, massive mudstones, bioturbated mudstones, lenticular bedded mudstones, heteroliths, wavy bedded sandstones, flaser bedded sandstones, sandstones with clay drapes, structureless sandstones (massive and bioturbated), parallel bedded sandstones, cross bedded sandstones, HCS (hummocky cross stratification) cross bedded sandstones, ripple bedded sandstones, herringbone cross bedded sandstones, chamosite sandstones, calcareous sandstones and arenaceous limestones, crinoidal limestones, conglomerates, condensed bed. Additionally, 15 ichnogenera of trace fossils: Asterosoma isp., Bergaueria isp., Chondrites isp., Diplocraterion isp., Gyrochorte isp., Lockeia isp., Ophiomorpha isp., Palaeophycus isp., Planolites isp., Rosselia isp., Skolithos isp., (?)Spongeliomorpha isp., Teichichnus isp., Terebellina isp. and Thalassinoides isp. were recognized in the Middle Jurassic deposits of Kuiavian Region. They point to sedimentation in the transition zone - foreshore environments. Based on the geochemical and palaeoecological investigations, four biofacies connected with different oxygenation of the bottom waters during sedimentation of the black shales have been proposed. The Upper Aalenian - Lower Bajocian deposits represent clayey sedimentation which occurred in dysoxic to anoxic environment. On the other hand, the Upper Bajocian - Lower Bathonian deposits represent dysoxic to oxic conditions. Sedimentation of the Middle Jurassic deposits in the central part of the Polish Basin took place in the shallow epicontinental sea, in environment spanning offshore to foreshore zones of a shallow siliciclastic shelf. Precise sedimentological studies point that the Middle Jurassic succession can be divided into 8 transgressive-regressive cycles. The oldest (Lower Aalenian) one begins with estuarine/foreshore sediments, sharply covered with offshore black shale facies. The Upper Aalenian, Bajocian and Lower Bathonian cycles are built of the transgressive offshore black shales and progradational regressive successions composed of mudstones and heteroliths and topped by shallow or middle shoreface sandstones. The Middle and Upper Bathonian cycles begin with transition zone sediments or lower shoreface deposits. The uppermost part of these cycles are built of sandstones and limestones representing the upper shoreface, foreshore and lagoon environments. The transgressive part of the last (Callovian) cycle is documented by carbonate-siliciclastic shoreface deposits which pass upwards into limestones of the Upper Jurassic. At the boundary between the Middle and the Upper Jurassic a condensed bed occurs.