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First discovery of Mississippian trace fossils in the Świebodzice Unit from the Witoszów region (SW Poland)

Muszer Jolanta

Geological Quarterly

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2020

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Vol. 64, No. 4

838--860

EN

Abundant and moderately diverse trace fossil assemblage have been discovered for the first time in mudstones of the Pogorzała Formation from the Witoszów region, SW Poland. Fifteen ichnospecies including fourteen ichnogenera are described. The ichnofauna is dominated by Dictyodora liebeana and contains numerous Palaeophycus tubularis, rarer Archaeonassa fossulata, Archaeonassa isp., Chondrites cf. intricatus, Curvolithus simplex, Diplopodichnus biformis, Lockeia isp., ?Lophoctenium isp., Nereites isp., Phycosiphon isp., Protovirgularia isp., ?Psammichnites isp., Taenidium isp. and one ichnospecies of fish swimming trails, Undichna cf. britannica. Some other structures (wave ripples influenced by microbial mats and zigzag structures) also occur. The trace fossil assemblages differ in various exposures, but three of them are similar and display the Dictyodora liebeana ichnoassemblage. It is represented mostly by the ethological categories fodinichnia and repichnia, with fewer pascichnia, domichnia and cubichnia. This new data from the Świebodzice Unit sheds light on the palaeontology, age and palaeoenvironment of the Pogorzała Formation. The occurrence of D. liebeana and U. cf. britannica indicates the Mississippian age of most mudstones studied, formerly considered Upper Devonian. The trace fossil assemblage belongs to the non-standard Nereites ichnofacies, without graphoglyptids. The lithological features of mudstones, trace fossil assemblage and poverty of macrofauna, testify to their deposition in a deeper sedimentation zone below storm wave base, most likely in dysaerobic, pro-delta conditions. This study suggests that rocks containing D. liebeana may form a correlative horizon in the Świebodzice Unit.

2

Genetic sequence stratigraphy on the basis of ichnology for the Middle Jurassic basin margin succession of Chorar Island (eastern Kachchh Basin, western India)

Darngawn Jehova L., Patel Satish J., Joseph Jaquilin K., Shitole Apuva D.

Geologos

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2019

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Vol. 25, No. 1

31--41

EN

Synrift basin margin successions are greatly influenced by eustatic sea level changes, tectonics and accommodation space filled in by sediments. The Middle Jurassic (Bajocian–Callovian) of Chorar Island (western India) comprises a ~109-m-thick synrift basin margin succession of clastic, non-clastic and mixed siliciclastic-carbonate rocks which are here analysed and categorised into nine lithofacies. The succession is bioturbated to varying intensities; 16 identified ichnogenera can be assigned to environmentally related groups of five trace fossil assemblages, which include Gyrochorte, Hillichnus, Rhizocorallium, Skolithos and Thalassinoides. These ichnoassemblages document the Skolithos and Cruziana Ichnofacies which marks a change in energy conditions, sedimentation dispersal patterns and bathymetry in a shallow-marine environment. The Bajocian–Callovian succession is further analysed on the basis of sedimentological and ichnological data that show two genetic sequences consisting of Transgressive Systems Tract and Highstand Systems Tract bounded by Maximum Flooding Surface. The synrift basin margin succession of the Middle Jurassic of Chorar Island shows cyclicity in deposition; the Bajocian–Bathonian succession represents progradational to retrogradational coastlines, while the Callovian succession documents an aggrading progradational coastline.

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Integrated sedimentological and ichnological study of the Coniacian sedimentation in North Sudetic Basin, SW Poland

Leszczyński S.

Geological Quarterly

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2018

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Vol. 62, No. 4

767--816

EN

Lithofacies and ichnological features of the Coniacian deposits of the upper part of Żerkowice Member and lowest part of the overlying Czerna Formation in southeastern part of the North Sudetic Synclinorium are described and their sedimentary palaeoenvironment is interpreted. The study confirms a shallow-marine to paralic/paludine palaeoenvironment. Sedimentation of the Żerkowice Member occurred in an upper shoreface environment dominated by waves, tidal currents and wave-generated alongshore currents, with an episodic encroachment of fore shore zone and shoal-water deltas. The interpretation is supported by a high-diversity assemblage of trace fossils with 21 ichnogenera, representing a stressed expression of the Skolithos Ichnofacies dominated by Ophiomorpha nodosa and a proximal expression of the Cruziana Ichnofacies with Thalassinoides and rare specimens of diverse other ichnotaxa. Sedimentation of the Czerna Formation commenced after a stasis, with at least a local hiatus caused by emergence, and proceeded in a laterally and vertically more varied environment, with transgressive coastal lagoons evolving into freshwater lakes and marshes and with a repetitive regressive intrusion of shoreface and shoal-water deltas. The emergence of the area is recorded by coal-bearing deposits with plant-root traces. Local occurrence of the Teredolites Ichnofacies in coal (peat) deposits above the base of the Czerna Formation indicates renewed marine flooding. Continuation of the latter is locally evidenced by a trace-fossil assemblage with 17 ichnogenera, representing proximal expression of the Cruziana Ichnofacies followed by distal expression of the Skolithos Ichnofacies in the overlying transgressive-regressive cyclothems. The palaeoenvironmental changes recorded by the sedimentary succession indicate bathymetric fluctuations and imply considerable shoreline shifts and palaeogeographic changes in the basin. These changes are interpreted as a combined signal of 2nd- and 3rd-order eustatic cycles, modified and partly obliterated by the effects of intrabasinal tectonic forcing and by palaeogeographically controlled variation in sediment supply.

4

Sedimentological and palaeoecological significance of the trace fossils of the Jurassic rocks of the Jhura Dome, Mainland Kachchh, western India

Patel S. J., Patel N. J.

Volumina Jurassica

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2015

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Vol. 13, no. 2

101--139

EN

The Middle to Late Jurassic succession of the Jhura Dome (Jhurio and Jumara formations) of the Mainland Kachchh, western India, comprises a ~500 m thick succession of clastic carbonates and mixed siliciclastic-carbonates, intercalated with shales. The sequence, as based on sedimentological characteristics, exhibits six sedimentary facies and four subfacies. Certain exceptional bands of the ripplemarked calcareous sandstone, shale and oolitic limestone facies are rich in ammonites, belemnites, brachiopods and bivalves. Thirty four ichnogenera were also identified and analysed paleoecologically. These trace fossils represent five ethological categories and six ichnoassemblages. Seventeen ichnoguilds are demonstrated based on space utilization for characterising the ecological complexity of ichnoassemblages. Bathymetric control of the trace fossils resulted with development of Skolithos, Cruziana and Zoophycos ichnofacies type conditions. The sedimentological and ichnological data analysis revealed seven distinctive depositional regimes ranging from offshore shelf below storm wave base to middle shoreface.

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Jurassic tetrapod footprint ichnofaunas and ichnofacies of the Western Interior, USA

Lockley M., Gierlinski G.

Volumina Jurassica

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2014

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Vol. 12, no. 2

133-150

EN

The Jurassic tetrapod track record of the Western Interior, USA, is one of the most diverse, complete and well-studied in the world, spanning a relatively continuous representation of Lower, Middle and Upper Jurassic formations. Although a few of these formations, notably the Morrison Formation, have yielded abundant body fossils, the majority lack abundant skeletal remains and, while trackrich, are in some cases completely barren of body fossils. Thus, the track record assumes great importance as the most complete and representative record of changing tetrapod faunas through time in a region where the body fossil record is often sparse or absent. In the Lower and Middle Jurassic, many distinctive assemblages are associated with eolian units (Wingate, Navajo and Entrada) that are almost devoid of body fossils. However, the former two units are rich in synapsid tracks characterized as the Brasilichnium ichnofacies. In the Middle Jurassic, fluctuating sea-levels exerted important controls on the distribution of theropod and pterosaur-dominated ichnofaunas associated with coastal plain and marginal marine settings. The Morrison ichnofauna is a reliable reflection of the body fossil record of that formation. Ongoing efforts to group and classify the various tetrapod ichnofaunas into tetrapod ichnofacies and tetrapod biochron categories have, in some cases, provoked stimulating, if sometimes inconclusive, debate.

6

Middle Turonian trace fossils from the Bystrzyca and Długopole sandstones in the Nysa Kłodzka Graben (Sudetes, SW Poland)

Chrząstek A.

Geological Quarterly

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2013

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Vol. 57, No. 3

443–-466

EN

The Middle Turonian sediments of the Nysa Kłodzka Graben (Bystrzyca Sandstone in the Stara Bystrzyca outcrop and the Długopole Sandstone in Długopole Górne Quarry) contain trace fossils, which include Curvolithus simplex, ?Macaronichnus isp., Ophiomorpha nodosa, Ophiomorpha isp., Palaeophycus tubularis, Thalassinoides cf. paradoxicus, T. suevicus and Thalassinoides isp. The assemblage of trace fossils points to the proximal Cruziana ichnofacies, that characterizes the distal lower shoreface and the archetypal Cruziana ichnofacies, typical of upper offshore settings. The trace fossils evidence implies that sedimentation took place in a shallow basin with periods of a sudden sediment input, good oxygenation and normal salinity. The Bystrzyca and Długopole sandstones are deposits of the shallow epicontinental sea that were deposited between the fair-weather and storm-wave base, in the distal lower shoreface–upper offshore setting. The Bystrzyca Sandstone is recognized as storm-originated deposits, whereas the Długopole Sandstone is probably the part of prograding “accumulation terrace”. The source of material for the sandstone was the East Sudetic Island and probably also the Orlica–Bystrzyca Uplift. The studied sandstones are related to a regression that started in the early/middle Middle Turonian and caused a relative uplift of the surrounding land.

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Neoichnology of an Arctic fluvial point bar, North Slope, Alaska (USA)

Martin A. J.

Geological Quarterly

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2009

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Vol. 53, No 4

383-396

EN

This study is the first to describe the neoichnology of an Arctic fluvial point bar (Colville River, Alaska, USA) and examine the sedimentological effects of tracemakers in this sedimentary setting. Seasonal extremes in discharge and sediment deposition in this system result in sandwaves, current ripples, gravel bars and mud veneers, with the latter forming extensive mudcracks. Organismal traces are abundantly represented in sandy mudflats on the downstream portion of the point bar and are characterized by: (1) abundant shallow horizontal invertebrate burrows and surface trails, directly comparable to Treptichnus, Cochlichnus and Aulichnites; (2) avian tracks and (3) large mammal tracks. Treptichnus-like burrows are attributed to dipteran larvae tracemakers, whereas Cochlichnus- and Helminthoidichnites-like trails were likely from nematodes or oligochaetes. Avian tracks are primarily from seagulls, geese, swans and plovers; mudcracks were connected directly to tracks, which developed as a result of in creased amounts of sunlight available during the polar summer. Mam mal tracks were dom i nated by those of caribou (Rangifer tarandus), but include grizzly bear (Ursos arctos) and other mammals. Caribou herds significantly impacted emergent and submergent mudflat surfaces through advection of saturated thixotropic muds and dry sand, while also fracturing mudcracked zones, and hence actively produced mud clasts. Vertebrates thus can cause considerable mixing, redistribution and erosion of sediments in Arctic point bars with only a few months of activity. Ichnodiversity was low but accompanied by high trace abundance, reflecting fa vorable hydrodynamic, solar and atmospheric conditions throughout a polar summer. In contrast, sedimentation and bioturbation are absent during winter months, when ice cover prevents organismal interactions with fluvial sediments. As a reult, the ichnocoenose does not fit easily into paradigms of previously defined continental ichnofacies (e.g., Mermia and Scoyenia) and is more like a composite ichnofacies. These findings can thus serve as a starting point for more detailed studies of circum polar point bars, while also adding new perspectives to the interpretation of trace fossils in circum polar fluvial environments.

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Trace fossils from the Lower-Middle Jurassic Bardas Blancas Formation, Neuquen Basin, Mendoza Province, Argentina

Bressan G., Palma R.

Acta Geologica Polonica

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2009

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Vol. 59, no. 2

201-220

EN

Trace fossil associations from the Lower.Middle Jurassic siliciclastic succession of the northern Neuquen Basin, Argentina are described and their palaeoenvironmental interpretation is discussed. The Bardas Blancas Formation displays facies of lower foreshore to offshore environments, such as massive and laminated mudstones, laminated siltstones, hummocky cross-stratified sandstones, massive and laminated sandstones, wave-rippled sandstones, as well as fine- to medium-grained bioclastic sandstones and massive conglomerates. They contain a trace fossil assemblage low in abundance but high in diversity. The assemblage, comprising eleven ichnogenera, is dominated by Skolithos, Chondrites, Thalassinoides, Planolites, Palaeophycus, Taenidium, Gyrochorte and Arenicolites. Gordia, ?Diplocraterion and Lockeia are less abundant. These trace fossils belong to the Skolithos, Cruziana and Zoophycos ichnofacies. Their distribution is controlled mainly by hydrodynamic energy, substrate consistency and oxygen levels. Storm beds exhibit two successive stages of colonization: (1) the pioneer stage, during which Skolithos, Diplocraterion and Arenicolites (elements of the Skolithos ichnofacies), were produced; and (2) the stable environment stage, represented by Chondrites, Thalassinoides, Taenidium, Gyrochorte, Gordia, Lockeia, Palaeophycus and Planolites (elements of the Cruziana ichnofacies). deeper environments exhibit a low diversity association with Chondrites and Thalassinoides, characterizing the Zoophycos ichnofacies.

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Ichnofabrics of the Upper Cretaceous fine-grained rocks from the Stołowe Mountains (Sudetes, SW Poland)

Rotnicka J.

Geological Quarterly

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2005

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Vol. 49, No. 1

15--30

EN

Upper Cretaceous fine-grained rocks (the “Plänermergel”) from the Stołowe Mountains are in general strongly bioturbated. The sections studied (180 m thick), located in the southern part of the mountains, are dominated by mudstones, marlstones and siltstones; sandstones, partly unbioturbated, are subordinate. The entire sequence shows a succession of ichnofabrics, which reflects a transgressive-regressive cycle (Cenomanian) and a regressive cycle (lower to middle/upper? Turonian). The trace fossil assemblage contains nine ichnogenera: Asterosoma, Cylindrichnus, Ophiomorpha, Palaeophycus, Phycosiphon, Planolites, Taenidium, Teichichnus, and Thalassinoides. Three basic types of ichnofabrics have been recognized: Ophiomorpha, Thalassinoides and Phycosiphon, all representing fully marine ichnofacies. The first two of these belong to the Cruziana ichnofacies, indicating the offshore zone, and the third one probably to the Zoophycos ichnofacies indicating a quiet shelfal setting below storm wave base.