Wyniki wyszukiwania - BazTech

1

Pioneer colonization, evidenced by Rhizocorallium in the Middle Triassic of Poland

Stachacz Michał

Annales Societatis Geologorum Poloniae

|

2023

|

Vol. 93, No. 4

363--379

EN

A large collection of the trace fossil Rhizocorallium from the Middle Triassic of the Polish part of the Germanic Basin (Peri-Tethys) is analysed and their ichnotaxonomical classification presented. Special attention is given to the deep form of Rhizocorallium with a vertical retrusive spreite, filled with faecal pellets, with detailed documentation of this structure, based on isolated specimens and serial sections. This analysis also reveals ∩-shaped and deep, protrusive structures. A former interpretation of Rhizocorallium as a rapidly formed fugichnion is not followed here; instead, an interpretation of the trace fossil as a complex fodinichnion is proposed. Scavengers and their relation to crinoid meadows, as well as predators, are indicated as potential tracemakers of some Rhizocorallium. Although Rhizocorallium is common throughout the Middle Triassic, unusual forms and the domination of substrates by Rhizocorallium in general mostly occur in the transgressive system of the lowermost Muschelkalk, and in regressive, marginal facies of the lower Keuper. Such a distribution of unusual forms of Rhizocorallium is interpreted as representing opportunistic, pioneer burrow assemblages that developed during the long-term benthic recovery after the P-T crisis, or in unfavourable conditions generally. Moreover, dynamic conditions with mixed clastic-carbonate sedimentation and rapidly varying salinity promoted smooth transitions from Rhizocorallium to Diplocraterion. Similar successions of dominant trace-fossil assemblages, of comparable sizes, occur in many sections around the world and demonstrate the record of slow recovery that continued through the Middle Triassic. The illustrated record of evolution of the Middle Triassic Rhizocorallium assemblages in Poland documents the last two stages of benthos recovery after the P-T boundary. A similar situation is observed around the world and, in many cases, great abundance of Rhizocorallium seems to be an indication of pioneer burrowing in dynamic, unfavourable environments.

2

Integrated microfacies, macrobenthos and trace-fossil analysis of the lower‒middle Miocene succession of Gebel Gharra, Cairo-Suez District, Egypt

Mandor Mona, El Hedeny Magdy, El-Sabbagh Ahmed, Nagm Emad, Abdelaal Abdelaal, Rashwan Mohamed, Mansour Heba

Annales Societatis Geologorum Poloniae

|

2023

|

Vol. 93, No. 4

381--409

EN

The palaeoecology and palaeoenvironments of the lower–middle Miocene succession in Gebel Gharra, NW of Suez, Egypt, are interpreted, on the basis of a detailed study of microfacies, trace fossils, and macrofaunal benthic assemblages. This succession consists of a lower siliciclastic part (the Gharra Formation) and a carbonate-dominated upper part (the Geniefa Formation), corresponding to a general transgression-regression cycle. Facies characteristics indicate depositional palaeoenvironments, ranging from supratidal, lagoonal, to shoal settings on an inner ramp that was influenced proximally by clastic input. At least seven ichnotaxa were recorded in the lower Miocene Gharra Formation, representing suites of the Skolithos ichnofacies. Among them, the ichnogenus Polykladichnus is recorded for the first time in Egypt. The macrobenthic taxa identified in 13 statistical samples are grouped into five assemblages (A–E) that are described and interpreted as the remains of communities. The faunal distribution and trophic structure of most of these assemblages confirm the existence of relatively stable and low-stress conditions. However, the trophic structure of the assemblages reflects the influence of particular environmental parameters, the dissolution of aragonitic shells and/or sample-size effects. Environmental parameters, controlling the distribution of trace and/or body fossils, include substrate consistency, bathymetry, water energy, productivity level, rate of sedimentation, salinity, and oxygen availability. The results of integrated lithoand biofacies analysis confirm that the succession studied was deposited in different environmental settings, providing perfect conditions for the occurrence and preservation of trace-fossil and macrobenthos assemblages.

3

Early Jurassic dinosaur-dominated track assemblages, floristic and environmental changes in the Holy Cross Mountains region, Poland

Pacyna Grzegorz, Ziaja Jadwiga, Barbacka Maria, Pieńkowski Paweł, Jarzynka Agata, Niedźwiecki Grzegorz

Geological Quarterly

|

2022

|

Vol. 66, No. 3

art. no. 29

EN

The Early Jurassic succession of the Holy Cross Mountains region in Poland offers a rare opportunity to study ecosystem complexity during the evolution and diversification of early dinosaurs, especially herbivorous ones. The section consists of continental and coastal deposits containing fossil assemblages spanning nearly 25 My of changes in terrestrial plants and some groups of invertebrates and tetrapods. Based on macrofossils and pollen and spores, the broader characteristics of the flora in this succession are presented. The floral assemblages show typical Early Jurassic characteristics and contain lycopsids, sphenopsids, ferns, cycadaleans, bennettitaleans, gnetaleans and ginkgoaleans, as well as conifers, and are similar to other Hettangian–Toarcian floral successions in Europe, showing the presence of a vast coniferous forest dominated by Hirmeriella in the early Hettangian, replaced by ginkgophyte-dominated floras in younger stages and araucarian conifer-dominated forests in the late Pliensbachian. Dinosaurs are documented mainly from their trace fossils (tracks and coprolites). Six distinct track assemblages (stratigraphically separated ichnoassemblages) of different ages can be identified. Current evidence indicates that while Anomoepus tracks are abundant throughout the long Hettangian–late Pliensbachian interval, medium-sized to large ornithischian tracks do not occur below the lower–middle Hettangian transition zone, associated with the first major marine transgression in the region. Hettangian strata with different theropod tracks (Grallator, Anchisauripus, Eubrontes, Kayentapus, cf. Megalosauripus), small Anomoepus tracks, numerous medium-sized Anomoepus-like tracks, Moyenisauropus tracks, tetradactyl tracks of sauropodomorphs (cf. Pseudotetrasauropus) and oval-shaped tracks of sauropods (Parabrontopodus) significantly contrast with the higher part of the Lower Jurassic succession (upper Pliensbachian Drzewica Formation and middle–upper Toarcian Borucice Formation) containing new types of medium-sized to large theropod tracks (Therangospodus), small and medium-sized bird-like tridactyl tracks (cf. Trisauropodiscus, cf. Anomoepus), exceptionally large, oval-shaped sauropod tracks (Sauropoda indet.), and new types of medium-sized and large ornithischian tracks (cf. Deltapodus, cf. Anomoepus). This points to a noticeable difference between the Hettangian and late Pliensbachian–Toarcian dinosaur ichnofaunas and may facilitate the study of regional and global changes and correlations. Both the palaeofloras and dinosaur trace fossils document ecosystem diversity and ecosystem changes, presented here in review form. The nature of these changes requires more detailed study, but preliminary results suggest the occurrence of rather complex and pronounced transformations in the dinosaur communities of the Holy Cross Mountains region. Based on our observations, the most significant event in Early Jurassic ecosystems took place within the Hettangian (change in floristic composition, the emergence of new groups of dinosaurs), but we also found what we believe to be a record of a major faunal turnover across the late Pliensbachian–middle–late Toarcian interval.

4

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

|

2021

|

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.

5

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

Muszer Jolanta

Geological Quarterly

|

2020

|

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.

6

Ichnology of Upper Cretaceous–lower Palaeogene deep-sea deposits in the Haymana Basin of Central Anatolia

Demircan Huriye, Görmüş Muhittin

Annales Societatis Geologorum Poloniae

|

2020

|

Vol. 90, No. 4

463--493

EN

Upper Cretaceous to lower Palaeogene carbonate and siliciclastic deposits that crop out widely in the Haymana and Polatlı districts (Ankara Province) of the Haymana Basin (Central Anatolia) are rich in larger benthic foraminifera, various macrofossils and ichnofossils. The ichnofossils of the Haymana and Yeşilyurt formations were studied at five localities. The Upper Cretaceous siliciclastics of the Haymana Formation contain moderately diverse trace fossils, belonging to the deep-sea Nereites ichnofacies. The Paleocene siliciclastic and carbonate deposits of the Yeşilyurt Formation comprise similar trace fossils, which do not show significant changes in comparison to the Haymana Formation. This indicates that the K-Pg boundary extinction event did not affect the ichnofauna with any longer consequences. The Upper Cretaceous coarser, siliciclastic deposits of the Haymana and Beyobası formations are rich in shallow-marine, larger benthic foraminifera, including species of Orbitoides, Omphalocyclus, Siderolites, Hellenocyclina, and Loftusia, whereas fine siliciclastic deposits contain abundant planktonic, open-marine foraminifera, such as Globotruncana and Heterohelix. Palaeogene siliciclastic to carbonate deposits of the Kartal, Yeşilyurt and Çaldağ formations are rich in the larger, benthic foraminifera Nummulites, Discocyclina, Assilina and Alveolina. The larger foraminifers have been redeposited from nearby, shallow-marine parts of the basin.

7

Paleozoiczne dowody na interakcje między roślinami a stawonogami

Muszer J., Jankowska A.

Przegląd Geologiczny

|

2018

|

Vol. 66, nr 8

503--509

EN

The aim of this paper is to summarize the current knowledge about the types of interactions between plants and arthropods and to present their evidences in the Paleozoic fossil record. A new classification of these evidences was proposed based on the function and reaction ofplants. This paper presents also their succession, correlated with phases of herbivore arthropod expansion, and phases of evolution ofplant-arthropod interactions in the Paleozoic.

8

Large cruzianid trace fossils in the Ordovician of the peri-Baltic area : the case of the Bukówka Formation (Holy Cross Mountains, Poland)

Stachacz M., Łaska W., Uchman A.

Geological Quarterly

|

2018

|

Vol. 62, No. 2

400--414

EN

The Middle Ordovician Bukówka Formation, composed of fine-grained quartz sandstones with siltstone intercalations, belongs to the Kielce Region of the Holy Cross Mountains (peri-Baltic palaeogeographic position). It contains trace fossils of low diversity and poor preservation. Particularly noteworthy are the large Cruziana and Rusophycus, that are typical of peri-Gondwanan areas. They consist of casts of bilobate furrows showing diverse preservation. Other trace fossils include mostly horizontal pascichnia, cubichnia, and fodinichnia, but also vertical domichnia. The trace fossil assemblage is typical of the archetypal Cruziana and partly of the Skolithos ichnofacies. Some beds contain abundant orthid brachiopods. The trace fossils and sedimentary structures (horizontal, low-angle and wave ripple cross-laminations, hummocky cross-stratification) suggest deposition on the middle and lower shoreface with storm influence. The poor preservation and low diversity of the trace fossils are related to the homogeneous lithology, low accumulation rate, shallow burial of organic matter and strong bioturbation. Therefore, animals burrowed strongly but mostly in shallow tiers. Thus, the preservation potential of their traces was much lower than in many peri-Gondwanan sections but still higher than in Baltica sedimentary rocks. This explains the provincial differences in ichnofauna during the Ordovician, which at least partly were influenced by the preservation potential.

9

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

Leszczyński S.

Geological Quarterly

|

2018

|

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.

10

New ichnotaxa of vertebrate burrows from the Salt Wash Member, Upper Jurassic Morrison Formation, south-eastern Utah (USA)

Raisanen D. C. W., Hasiotis S. T.

Annales Societatis Geologorum Poloniae

|

2018

|

Vol. 88, No. 2

181--202

EN

Large-diameter burrows in pedogenically modified floodplain deposits in the Salt Wash Member, Upper Jurassic Morrison Formation, southeast Utah, U.S.A., are interpreted to have been constructed by mammals. They are distinguished as Daimonelix martini isp. nov., which exhibits a helical shaft down to a horizontal tunnel with a mean depth of 71.4 cm from the inferred palaeosurface. The mean path length of the shaft is 99.4 cm; mean dip of the whorls is 39°. The mean tunnel length is 42.3 cm. Shafts and tunnels are oval or elliptical in cross section with the horizontal diameter slightly larger than the vertical (ratio of -1.26:1); the shaft averages 9.2 cm wide and 7.3 cm tall; the tunnel averages 10.7 cm wide and 10.7 cm tall. The tracemaker was likely a fossorial mammal that used the burrow as a den to shelter when not foraging above ground; the burrows are domichnia. The other from the same member is Fractisemita henrii igen. nov. et isp. nov., a network of interconnected shafts and tunnels; shaft and tunnel segments are straight, curved, or helical. The segments are at angles of 0-89°; mean length of a section is 30.7 cm. The cross sections of all elements are oval or elliptical; the mean width is 6.3 cm and the mean height is 4.9 cm (ratio of -1.29:1). The burrows are interpreted as the work of a social mammal and represent multiple tracemaker behaviours: protection, denning, foraging, and possibly food storage. The burrows are polychresichnia. Surficial morphologic features preserved on the burrow walls of both types are interpreted as scratches made by the tracemaker claws and/or teeth. The burrows reveal the actions of small vertebrates not recorded by body fossils showing potential partitioning of the environment and availability of resources for small vertebrates.

11

Ichnotaxonomy as a science

Rindsberg A. K.

Annales Societatis Geologorum Poloniae

|

2018

|

Vol. 88, No. 2

91--110

EN

If ichnotaxonomy is to be scientific, then its results must be repeatable. While some ichnotaxa are identified consistently, others are not, suggesting that ichnotaxonomy is not a mature science. When researchers disagree on the identification of a specimen, it suggests that closer examination is needed: an intermediate stage in the scientific method. But when ichnologists publish different names for the same trace fossils, multiple trials of classification have yielded different results, suggesting a failure of the hypotheses that led to the names. The burgeoning of invertebrate ichnology from the 1960s onward was made possible by demonstrating its utility to the petroleum industry; in part, this was accomplished by simplifying the ichnotaxonomy of common trace fossils to the point where a specialist was not required to make use of them in sedimentology and stratigraphy. The biological aspect of trace fossils, albeit of great interest, was downplayed in favour of a severely geometric approach. Ironically, this has had the effect of obscuring basic relationships of trace fossils and their palaeoenvironments that could be of great use to sedimentologists. Previous researchers have emphasized the value of a uniform approach in ichnotaxonomy. To accomplish this, ichnologists should take inspiration from the taxonomy of body fossils. Making ichnotaxonomy more replicable will take time and effort among investigators. In the long run, this can be accomplished by a holistic approach that includes close observation of trace fossils, standardized procedures of description and diagnosis, reinvestigation of type material, attention to bioprint (morphological traits that reveal the anatomical and ethological characteristics of the tracemakers; Rindsberg and Kopaska-Merkel, 2005), avoidance of taphonomic and human bias, and above all, cooperation.

12

Ichnofossil assemblages and palaeosols of the Upper Triassic Chinle Formation, south-eastern Utah (USA) : Implications for depositional controls and palaeoclimate

Fischer J. S., Hasiotis S. T.

Annales Societatis Geologorum Poloniae

|

2018

|

Vol. 88, No. 2

127-- 162

EN

The Upper Triassic Chinle Formation in the Stevens Canyon area in south-eastern Utah represents fluvial, palustrine, and lacustrine strata deposited in a continental back-arc basin on the western edge of Pangea. Previous investigations interpreted a megamonsoonal climate with increasing aridity for the Colorado Plateau towards the end of the Triassic. In this study, we systematically integrate ichnological and pedological features of the Chinle Formation into ichnopedofacies to interpret palaeoenvironmental and palaeoclimatic variations in the north-eastern part of the Chinle Basin. Seventeen ichnofossil morphotypes and six palaeosol orders are combined into twelve ichnopedofacies, whose development was controlled by autocyclic and allocyclic processes and hydrology. Ichnopedofacies are used to estimate palaeoprecipitation in conjunction with appropriate modern analogue latitudinal and geographic settings. In the north-east Chinle Basin, annual precipitation was -1100-1300 mm in the Petrified Forest Member. Precipitation levels were >1300 mm/yr at the base of the lower Owl Rock Member, decreased to -700-1100 mm/yr, and then to -400-700 mm/yr. Two drying upward cycles from -1100 mm/yr to -700 mm/yr occurred in the middle and upper part of the Owl Rock Member. In the overlying Church Rock Member, precipitation decreased from -400 mm/yr at the base of the unit to -25-325 mm/yr at the end of Chinle Formation deposition. Ichnopedofacies indicate monsoonal conditions persisted until the end of the Triassic with decreasing precipitation that resulted from the northward migration of Pangea. Ichnopedofacies in the northeast Chinle Basin indicate both long-term drying of climate and short-term, wet-dry fluctuations.

13

Palaeoecologic significance of the Callovian-Oxfordian trace fossils of Gangeshwar Dome, Southeast of Bhuj, Mainland Kachchh, India

Bhatt N. Y., Patel S. J.

Volumina Jurassica

|

2017

|

Vol. 15, no 1

17--40

EN

The shallow marine deposits of the Late-Middle Jurassic (Callovian–Oxfordian) Jumara Formation of the Gangeshwar Dome of Mainland Kachchh, India, comprise a succession of ~247 m thick clastic sediments with few non-clastic bands and contain a diverse group of ichnofauna. The succession is subdivided into seven lithofacies, viz., laminated shale-siltstone facies (LSS), sheet sandstone facies (SS), herringbone sandstone facies (HS), bivalve sandstone facies (BS), bioclastic limestone facies (BL), intraformational conglomerate facies (IC) and oolitic limestone facies (OL). The ichnofaunal study shows 29 ichnospecies of 23 ichnogenera including Arenicolites, Bifungites, Bolonia, Chondrites, Didymaulichnus, Diplocraterion, Gyrochorte, Helminthopsis, Isopodichnus, Laevicyclus, Lockeia, Monocraterion, Taenidium, Ophiomorpha, Palaeophycus, Planolites, Phycodes, Protopalaeodictyon, Rhizocorallium, Skolithos, Thalassinoides, Tisoa, and Zoophycos. These trace fossils are distributed among nine ichnocoenose, characterized by Chondrites, Diplocraterion, Gyrochorte, Ophiomorpha, Rhizocorallium, Skolithos, Taenidium, Thalassinoides and Zoophycos. Their occurrence in the facies corresponds to their trophic and ethological properties. The colonisation of the opportunistic Diplocraterion and the Skolithos ichnocoenose shows a high den¬sity and marks foreshore/nearshore environmental conditions. The Gyrochorte, the Rhizocorallium, the Taenidium and the Thalassinoides ichnocoenose indicate the typically lower energy zone of the shoreface-offshore region. The Chondrites ichnocoenosis indicates fluctuation in bottom water oxygen while the Zoophycos ichnocoenosis typically exploited a calm water niche in the offshore region. These ich-nocoenose recur throughout the sequence and belong to the Skolithos and the Cruziana ichnofacies which marked changes in energy gradient, substrate stability, water depth and mode of life of invertebrate organisms. The study of trace fossil assemblages with sediment characteristics gives a detailed and accurate picture of foreshore to offshore palaeoenvironmental conditions.

14

Ichnology of the Cambrian Ociesęki Sandstone Formation (Holy Cross Mountains, Poland)

Stachacz M.

Annales Societatis Geologorum Poloniae

|

2016

|

Vol. 86, No. 3

291--328

EN

Quartz arenites and wackes with intercalations of silty shales of the Ociesęki Formation were analysed in small outcrops and one core. The succession contains about forty-three ichnogenera and seventy-four ichnospe- cies, among which thirty-three ichnogenera and fifty-three ichnospecies are described by present author. The formation belongs to the Schmidtiellus-Holmia Superzone and to the Protolenus-Issafeniella Zone. Most strata are totally bioturbated. The diverse and numerous trace fossils represent the Cruziana ichnofacies in the lower part of the formation and the Skolithos ichnofacies in the upper part. A few possibly new ichnospecies of different ichnogenera have been described in open nomenclature. Sedimentary structures and trace fossil assemblages indicate that the older part of this formation was deposited on the upper offshore to lower shoreface, while its younger part was deposited on the lower to middle shoreface, where storm episodes were the main factor controlling sedimentation and the activity of benthos. The trace fossil associations studied are similar to those from the lower Cambrian in many places around the world. The ichnoassociations from the Polish part of the East European Platform and from Sweden, which represent the Baltica palaeocontinent, display the closest similarity.

15

Trace fossils from the continental Upper Triassic Kågeröd Formation of Bornholm, Denmark

Knaust D.

Annales Societatis Geologorum Poloniae

|

2015

|

Vol. 85, No. 3

481--492

EN

The Upper Triassic Kågeröd Formation of Bornholm consists of clays, sandstones and conglomerates of floodplain and fluvial origin, but details of the depositional environment are poorly understood. Trace fossils are described for the first time from the red and green clays (floodplain with lake deposits) and cross-stratified sandstones (fluvial channel deposits) of the Upper Triassic Kågeröd Formation on Bornholm, Denmark. The sparse ichnofauna consists of large, mud-filled shafts and tunnels in caliche-bearing conglomerate, determined as Camborygma and attributed to the burrowing activity of cray fish. The sandstones preservevertical U-shaped burrows passively filled with sand, assigned to Arenicolites and probably produced by insects. Furthermore, they contain winding, horizontal, oblique and vertical unbranched burrows with an active meniscate sandfill, referable to Taenidium and supposedly produced by burrowing beetles. The clays and the sandstones contain numerous caliche nodules of centimetre to decimetre size, some of which contain root traces in the form of rhizoliths. This trace-fossil association reflects deposition on a vast floodplain with shallow lakes and fluvial channels, under semiarid conditions.

16

Ichnofabric characterization in cores : a method of digital image treatment

Rodríguez-Tovar F. J., Dorador J.

Annales Societatis Geologorum Poloniae

|

2015

|

Vol. 85, No. 3

465--471

EN

Ichnofabric analysis, as a relatively young ichnological approach, has witnessed rapid growth, showing its usefulness in basin analysis, with special attention to palaeoenvironmental interpretations. The ichnofabric approach has evolved from the description of trace composition and the intensity of bioturbation to integrate detailed information on numerous ichnofabric features, such as primary sedimentary structures, ichnological diversity, ichnological features, cross-cutting relation ships or tiering structures. This development has been associated with its application to the study of deep-sea sediments, especially in research on cores, which is not easy, owing to the particular features of cores. Here a method for improving ichnofabric characterization in modern marine cores is presented, on the basis of digital high-resolution image treatment, with special emphasis on the quantification of ichnofabric attributes. The proposed methodology is based on the modification of three image adjustments (image adjustment), the estimation of the percentage of the area occupied by bioturbation (digital estimation), the lateral and vertical quantification and comparison of pixel values for the infill of the trace fossils and the host sediment (pixel counting), and the integration of the information obtained in the visual representations of ichnofabrics (the ichnofabric representation). The sequential application of these proposed steps allow, 1) better identification of trace fossils, together with cross-cutting relation ships and the characterization of trace-fossil assemblages, 2) estimation of the percent age of bioturbation associated to each ichnotaxon, the whole ichnocoenosis, or a complete ichnofabric, 3) differentiation between biodeformational structures and trace fossils, discrimination between ichnotaxa, distinction between passively and actively infilled structures, and 4) evaluation of the depth of penetration by particular tracemakers.

17

Disappeared almost without a trace : Taphonomic pathways and the recognition of hidden bioturbation events in Eocene storm deposits (Paují Formation, Lake Maracaibo, Venezuela)

Buatois L. A., Delgado M., Mángano M. G.

Annales Societatis Geologorum Poloniae

|

2015

|

Vol. 85, No. 3

473--479

EN

Shallow-marine deposits, included in the “Basal Sands” of the Eocene Paují Formation of the Maracaibo Basin in western Venezuela, record deposition in fore shore to lower off shore settings. These deposits are stacked in coarsening-upward parasequences that reflect variable intensities and frequencies of storms. Of particular interest are sharp-based, amalgamated, hummocky cross-stratified and rippled, very fine-grained sandstone beds, observed in the core MOT-X from the Motatán Field. These beds record storm deposition, under purely oscillatory to combined flows in an offshore-transition setting. The amalgamated nature of the sand stone interval indicates repeated erosion, due to multiple storm events. The ichnofabrics in these tempestites result from a distinctive taphonomic pathway, reflecting the interplay between bioturbation events and storm erosion and deposition. The storm-related trace-fossil suite is represented by Diplocraterion parallelum and local occurrences of Palaeophycus tubularis, Bergaueria isp. and Thalassinoides isp., which is consistent with the relatively high energy of formation of these deposits. Fair-weather deposits are absent from the sand stone interval. However, high densities of Chondrites isp. are present in the infills of Diplocraterion parallelum and, more rarely, Thalassinoides isp. providing the sole evidence of the establishment of a resident fauna during inter-storm intervals. Deposits containing the fair-weather suites were erosionally removed during the subsequent storm. The deep-tier emplacement of Chondrites and the ability of its producer to rework other biogenic structures favour preservation, allowing recognition of a “hidden” bioturbation event that otherwise might have remained undetected.

18

Construction of ichnogeneric names

Rindsberg A. K.

Annales Societatis Geologorum Poloniae

|

2015

|

Vol. 85, No. 3

529--549

EN

Ichnologists have over used the root ichn- “trace”, employing it in new terms and new ichnogenera alike, to the point where it can be difficult to express one self clearly without using it several times in one sentence. The root derives from Ancient iχνος (ichnos), which means “foot print” or “track”, or by extension a “trace”, any sign of an animal’s activity. Perhaps it is time to explore the use of other roots to create new ichnologic terms and genera. Alternative Latin and Greek roots are given here, as well as ad vice on how to construct new ichnogenera in a technically correct and aesthetically pleasing manner.

19

Bioerosional ichnotaxa and the fossilization barrier

Bromley R. G., Nielsen K. S. S.

Annales Societatis Geologorum Poloniae

|

2015

|

Vol. 85, No. 3

453--455

EN

For the establishment of a new ichnogenus or ichnospecies, the type material shall be fossil, not unfossilized material. This is not always possible, because the transition between the two states, the fossilization barrier, is extremely vague defined. In most fossil material, this is not a problem. However, in the case of bioerosion structures (borings, rasping traces, attachment scars in hard substrates), the problem is serious. For example, when does a sponge boring in an oyster shell be come fossilized? The question arises when Recent and sub-Recent materials are considered. Two examples are discussed. (1) Microborings are described and named in foraminifera dredged from the sea floor. In this material, it is not possible to distinguish between “fossilized” and “unfossilized” foraminifera. Bioturbation and other processes may have mixed recently dead, Pleistocene and older foraminifera in the sea-floor sediments. (2) Small, characteristic borings are made by slipper limpets in pagurized gastropod shells. The structures would constitute a new ichnospecies of Oichnus, but these borings have not been found in “fossilized material” and the borings therefore remain nameless. Because bioerosion structures constitute “ready-made fossils”, it is suggested that the onset of fossilization be equated with the death of the bioeroding tracemaker.

20

Eocene flora and trace fossils from the Hruby Regiel section in the Tatra Mountains (Poland): Taxonomic revision of the Wiktor Kuźniar fossil plant collection

Worobiec G., Jach R., Machaniec E., Uchman A., Worobiec E.

Acta Geologica Polonica

|

2015

|

Vol. 65, no. 2

203--226

EN

Latest Eocene plant macrofossils and trace fossils collected a century ago by Wiktor Kuźniar are revised and their stratigraphical and palaeoecological meaning is re-considered. They derive from marine limestones and marls cropping out on the northern slope of the Hruby Regiel mountain in the Western Tatra Mountains. Leaves belonging to the families Fagaceae and Lauraceae and fruits of the palm Nypa are recognized. The co-occurrence of the planktonic foraminifer taxa Chiloguembelina cf. gracillima and Globigerinatheca cf. index and fruits of Nypa suggests a latest Eocene age of the fossil flora. The plant assemblage is typical of paratropical or subtropical evergreen forests in a warm and humid subtropical climate, recent counterparts of which occur in southeast Asia. The presence of Nypa is characteristic of mangroves. The good state of preservation of the leaves suggests coastline proximity during sedimentation of the plant-bearing deposits.