Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "fossils" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 69
Tytuł:
Cambrian limestone erratics in the Tertiary glacio-marine sediments of King George Island, West Antarctica
Autorzy:
Wrona, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/2052948.pdf
Data publikacji:
1989
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctica
glacial erratics
Cambrian fossils
paleogeography
Źródło:
Polish Polar Research; 1989, 10, 4; 533-553
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lower Cambrian trace fossils from the Holy Cross Mountains, Poland
Autorzy:
Orłowski, S.
Żylińska, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059927.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Lower Cambrian
trace fossils
Opis:
Additional data on the Lower Cambrian ichnotaxa from the Holy Cross Mountains are presented. Nine ichnotaxa are described for the first time from the area, additional descriptions of three known ichnotaxa are supplied, and two ichnotaxa are shown to have extended stratigraphic ranges. Most Lower Cambrian trace fossils belong to the Cruziana ichnofacies. The high taxonomic diversity of the Early Cambrian trace fossil assemblages from the Holy Cross Mountains in comparison to the trace fossil assemblages of the Mid- and Late Cambrian of the area is confirmed.
Źródło:
Geological Quarterly; 2002, 46, 2; 135-146
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A mixed assemblage of deep-sea and shelf trace fossils from the Lower Cretaceous (Valanginian) Kamchia Formation in the Troyan region, central Fore-Balkan, Bulgaria
Autorzy:
Uchman, A.
Tchoumatchenco, P.
Powiązania:
https://bibliotekanauki.pl/articles/973639.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
trace fossils
ichnology
Lower Cretaceous
Fore-Balkan
Bulgaria
Opis:
Trace fossils collected from the best outcrop of the Kamchia Formation have been analysed. There are thirteen ichnotaxa (Curvolithus simplex, Gyrochorte isp., ?Helminthoidichnites tenuis, Multina minima [second occurrence], Palaeophycus tubularis, ?Palaeophycus isp., Phycodes bilix, Phycosiphon incertum, Planolites cf. reinecki, Spongeliomorpha ?chevronensis, Squamodictyon tectiforme, Thalassinoides suevicus, Zoophycos isp.) representing different ethologic, toponomic and preservational types, and produced at different depths in the sediment. The ichnoassemblage contains a mixture of forms typical of flysch (Squamodictyon) and shelf deposits (Curvolithus, Gyrochorte). Probably, sediments of the Kamchia Formation were deposited in an offshore or deeper basin with storm deposition of sand beds and background marly sedimentation. It is possible that storm currents transported trace makers of the shelf trace fossils to the deeper sea. It is not excluded that the trace maker of Gyrochorte migrated to the deep-sea after the Jurassic. However, the simplest explanation is that the Kamchia ichnofauna represents an ecological transition between shelf and slope communities.
Źródło:
Annales Societatis Geologorum Poloniae; 2003, 73, No 1; 27-34
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bioturbation structures in the Holovnia Siliceous Marls (Turonian-lower Santonian) in Rybotycze (Polish Carpathians)
Autorzy:
Leszczyński, S.
Powiązania:
https://bibliotekanauki.pl/articles/191521.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
trace fossils
carbonate turbidites
Turonian-lower Santonian
Skole Nappe
Carpathians
Polska
Opis:
The Holovnia Siliceous Marls represent carbonate turbidites interbedded with non-calcareous pelagic/hemipelagic shales. This study reports on bioturbation pattern, trace fossil assemblage and distribution of bioturbation structures, i.e. structures resulting from the life activity of organisms in general, in the succession exposed in the village of Rybotycze. 20 ichnospecies were identified, with one new ichnogenus (Squamichnus) and one new species (Squamichnus acinaceformis). The ichnofossils represent nearly exclusively fodinichnia produced close to the seafloor, below calcite compensation depth. Shallow location of anoxic pore waters is indicated to be responsible for relatively shallow bioturbation depth whereas variability in frequency of turbidite sedimentation and petrographic composition of turbidites is suggested as the chief control on the vertical distribution of the bioturbation structures in the succession.
Źródło:
Annales Societatis Geologorum Poloniae; 2003, 73, No 2; 103-122
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bioturbation structures of the Kropivnik Fucoid Marls (Campanian-lower Maastrichtian) of the Huwniki-Rybotycze area (Polish Carpathians)
Autorzy:
Leszczyński, S.
Powiązania:
https://bibliotekanauki.pl/articles/2058753.pdf
Data publikacji:
2004
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Polska
Carpathians
Upper Cretaceous
marlstone
flysch
trace fossils
Opis:
The Kropivnik Fucoid Marls of the Polish Outer Carpathians contain numerous bioturbation structures, and comprise thin-bedded sandstones, hard and soft marlstones and muddy to clayey, mainly turbiditic shales. Comparison of three sections elucidated the stratigraphic and sedimentological controls on the distribution of the bioturbation structures, which are most common on the soles of sandstone beds, and within and on the tops of beds of hard marlstone overlain by shale. Most of the bioturbation structures are taxonomically undeterminable. Nevertheless, twenty seven ichnospecies, including one new ichnospecies (Taenidium recurvum), and seven forms of trace fossils of unknown taxonomic affinity were recognised. Most ichnotaxa were observed as individual specimens. Irregular structures apparently formed by the squashing of burrows filled with fluidised fill, called here turbidichnia, are quite common in some marlstone beds in the lower part of the succession. Planolites beverleyensis and Halopoa imbricata are the most frequent trace fossils on the lower surfaces of sandstone beds. Chondrites intricatus, Planolites beverleyensis and Thalassinoides suevicus represent the most common taxa in hard marlstones. Endoreliefs of Scolicia isp. are quite frequent in the top parts of marlstone beds in some parts of the succession. Other ichnotaxa were found either rarely or as single specimens only. The burrowing depth, reaching 15 cm below the tops of normally-graded rhythmic units, together with the relatively rich trace fossil assemblage and common occurrence of Planolites and Thalassinoides, is interpreted as indicating fully oxic conditions at the bottom of the sedimentary basin.
Źródło:
Geological Quarterly; 2004, 48, 1; 35--60
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemical and ecological aspects of lower Frasnian pyrite-ammonoid level at Kostomłoty (Holy Cross Mountains, Poland)
Autorzy:
Racki, G.
Piechota, A.
Bond, D.
Wignall, P. B.
Powiązania:
https://bibliotekanauki.pl/articles/2060630.pdf
Data publikacji:
2004
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Frasnian
pyritic fossils
geochemical proxies
anoxia
Timan Event
Opis:
The lower Frasnian (transitans Zone with Ancyrodella priamosica = MN 4 Zone) rhythmic basin succession of marly limestones and shales (upper Szydłówek Beds) at Kostomłoty, western Holy CrossMts., Central Poland, contains a record of the transgressive-hypoxic Timan Event in this drowned part of southern Laurussian shelf. The unique facies consists of organic-rich marly shales and a distinctive pyritic, goniatite level, 1.6mthick. The faunal assemblage is dominated by pyritized shells of diminutivemollusks with cephalopods (including goniatites Epitornoceras and Acanthoclymenia), buchioline bivalves (Glyptohallicardia) and styliolinids. This interval is marked by moderately low Th/U ratios and pyrite framboid size distributions suggestive of dysoxic rather than permanent euxinic conditions. The scarcity of infauna and bioturbation resulted in finely laminated sedimentary fabrics, as well as the low diversity of the presumed pioneer benthos (mostly brachiopods). In the topmost part of the Szydłówek Beds, distinguished by the Styliolina coquina interbedded between limestone-biodetrital layers, the above geochemical proxies and C-isotope positive shift indicate a tendency to somewhat increased bottom oxygen deficiency and higher carbon burial rate linked with a bloom of pelagic biota during high-productivity pulse. The geochemical and community changes are a complex regional record of the initial phase of a major perturbation in the earth-ocean system during a phase of intermittently rising sea level in the early to middle Frasnian, and associated with the highest positive C-isotope ratios of the Devonian.
Źródło:
Geological Quarterly; 2004, 48, 3; 267--282
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deformacje skamieniałości śladowych a proces kompakcji w wapieniach mikrytowych górnej jury okolic Korzkwi (Wyżyna Krakowska)
Deformations of trace fossils versus compaction in micritic limestones, an example from Korzkiew, Upper Jurassie (Kraków Upland)
Autorzy:
Ziółkowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/2077307.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
trace fossils
compaction
Kraków Upland
Oxfordian
paleorelief
firmground
skamieniałości śladowe
zagęszczanie
Wyżyna Krakowska
Oksford
Opis:
Upper Jurassie (Oxfordian, Bimmammatum Zone) micritic limestones show presence of omission surface of firmground character with trace fossils assemblage. Deformations of burrows are used to quantitative determination of mechanical compaction, applying Ricken's model. Presented results may be used in reconstruction of sea bottom relief during Late Jurassie in area of study.
Źródło:
Volumina Jurassica; 2005, 3, 1; 55--61
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ichnofabrics of the Upper Cretaceous fine-grained rocks from the Stołowe Mountains (Sudetes, SW Poland)
Autorzy:
Rotnicka, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059546.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Stołowe Mountains
Cretaceous
fine-grained rocks
trace fossils
ichnofabrics
ichnofacies
Opis:
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.
Źródło:
Geological Quarterly; 2005, 49, 1; 15--30
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Opportunities and constraints for reconstructing palaeoenvironments from stable light isotope ratios in fossils
Autorzy:
Lee-Thorp, J. A.
Sponheimer, M.
Powiązania:
https://bibliotekanauki.pl/articles/2060629.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
stable light isotopes
fossils
vertebrates
diagenesis
environmental reconstruction
Opis:
Stable light isotope ratios (13C/12C and 18O/16O) in fossilteeth provide key archives for understanding ecology of past faunal communities and the evolution of environments during the Plio-Pleistocene. Given the inevitable processes of diagenesis during fossilisation, the integrity of isotopic in formation and the degree of detailed in formation that can be extracted, remain important issues in all fossil studies. The most appropriate tests are those in trinsic to isotopic abundances in ecosystems. They are easier to develop for 13C/12C in savanna environments where large 13C/12C differences exist between C4 tropical grasses and C3 trees and shrubs. Validating 18O/16O ratios in fossil carbonate or phosphate is more difficult, but patterned variability, mainly tracking water-related behaviour, within modern faunal communities has been replicated in several fossil as semblages. The identification of seasonal variation in 13C/12C and 18O/16O along the growth axis of a tooth crown, also applicable in areas composed solely of C3 plants, fills a dual role as a test and for providing data on seasonal amplitude. The results of studies from low- and mid-latitude African sites suggest that isotopic variation in rain fall on short timescales and ecological differences amongst animals, dominate over smaller differences in 18O16O composition due to temperature.
Źródło:
Geological Quarterly; 2005, 49, 2; 195-204
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New trace fossils from the La Meseta Formation (Eocene) of Seymour Island, Antarctica
Autorzy:
Uchman, Alfred
Gaździcki, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/2051913.pdf
Data publikacji:
2006
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctica
Eocene
trace fossils
Źródło:
Polish Polar Research; 2006, 27, 2; 153-170
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zagadkowa roślina z wczesnej jury Gór Świętokrzyskich
An Early Jurassic problematical plant from the Holy Cross Mountains, central Poland
Autorzy:
Gierliński, G.D.
Ploch, I.
Sabath, K.
Ziaja, J.
Powiązania:
https://bibliotekanauki.pl/articles/2074472.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
roślina nagozalążkowa
skamieniałość roślinna
wczesna jura
Góry Świętokrzyskie
Gymnospermae
macroflora
plant fossils
Early Jurassic
palaeoecology
Opis:
Fossils plants (less than 0.5 m high) preserved in upright position were found in Śmiłów Quarry (E of Szydłowiec) at the northern slope of the Holy Cross Mountains. The plants were preserved as impressions of ascending narrow-leafed stems in fine-grained sandstone of the Drzewica Formation (upper Pliensbachian). The leaves are 5-25 cm long and about 2-5 mm wide; the angle between them and the short main axis ranges within 20-30o. Morphology of the plant resembles schizeacean ferns, but also that of Aethophyllum stipulare Brongniart 1828 from Anisian of France, recognized by Grauvogel-Stamm (1978) as an herbaceous gymnosperm. Grauvogel-Stamm (1978) supposed that the leaves Podozamites and cone scales Swedenborgia, common in Jurassic strata of higher palaeolatitudes, are derived from descendants of Aethophyllum. Podozamites leaves often occur in many dinosaur track-bearing horizons in the Polish Jurassic. Thus, herbaceous conifers might have played an important and often underestimated role in the Mesozoic ecosystems (possibly as a substantial part of dinosaur diet). The possiblity of coniferous equivalents of Cenophytic herbaceous angiosperms, as well as a possibility of their coevolution with Mesozoic low browsing and grazing herbivore megafauna is worth further palaeobotanical and palaeoecological studies.
Źródło:
Przegląd Geologiczny; 2006, 54, 2; 139-141
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gniazdowe akumulacje szczątków fauny w środkowojurajskich iłach rudonośnych Wyżyny Krakowsko-Częstochowskiej-wnioski paleobiologiczne
Nest-like accumulations of faunal remains in the Middle Jurassic ore-bearing clays of the Kraków-Czestochowa Upland and their palaeobiological implications
Autorzy:
Zatoń, M.
Salamon, M. A.
Marynowski, L.
Zatoń, R.
Powiązania:
https://bibliotekanauki.pl/articles/2074537.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
średnia Jura
Polska
fragmenty skorup
szczątki organiczne
Middle Jurassic
Polska
predation
shell fragments
shelly fossils
Opis:
Distinct faunal accumulations in the uppermost Bajocian/lowermost Bathonian, lowermost and Middle Bathonian of the Polish Jura (south-central Poland) have been detected. The fossils are densely packed in the centre of the accumulations and more or less dispersed in their margins. The accumulations vary in size, but all are rich in various groups of organisms, of which the molluscs (mainly bivalves) and echinoderms predominate. The echinoderms are all disarticulated, and shelly fauna occur as angular fragments with sharp edges, of random sizes and without any signs of abrasion. The different sizes of the fossil remains, from tiny echinoderm ossicles or juvenile shelly fauna to medium-sized shell fragments or belemnite rostra, exclude any transportation and thus sorting. Worth of noting is the occurrence of similar faunal groups in each accumulation. The general shape and composition of the accumulations, as well as their taphonomical features, especially the angularity of shell fragments, point to durophagous (shell-crushing) predation rather than physical processes. The various organisms may indicate that the potential predator (most probably fish) fed on various invertebrates. The indigestible particles were later regurgitated forming the accumulations discussed. The presence of various epibionts on the fossil fragments indicate,that they rested upon the sea-floor for some time-span after they had been regurgitated. Then the scavengers, as well as current action or water movements, have been responsible for dispersion of some of the fossils, as is well-visible at the margins of the investigated accumulations..
Źródło:
Przegląd Geologiczny; 2007, 55, 5; 424-429
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Invertebrate trace fossil assemblages from the Lower Hettangian of Sołtyków, Holy Cross Mountains, Poland
Autorzy:
Pieńkowski, G.
Niedźwiedzki, G.
Powiązania:
https://bibliotekanauki.pl/articles/2061345.pdf
Data publikacji:
2008
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Hettangian, Lower Jurassic
invertebrate trace fossils
bivalves
crayfishes
insects
continental ichnofacies
Holy Cross Mountains
Polska
Opis:
Invertebrate trace fossil assemblages from the Hettangian (Early Jurassic) alluvial plain deposits of Sołtyków (Holy Cross Mts, Poland) represent three terrestrial ichnofacies: the Mermia ichnofacies (entirely aquatic), Scoyenia ichnofacies, and Coprinisphaera ichnofacies. They span environments from shallow lacustrine to different subaerial fluvial environments. Bivalve burrows and traces, oligochaetae, insect and crayfishes burrows, plant roots, vertebrate tracks and other types of trace fossils record information on biodiversity and palaeoecological conditions. The Sołtykow ichnoassemblages confirm that terrestrial ichnocoenoses were quite diversified, chiefly a result of a changing water table and food availability. Diversity of trace fossils was supported by the strongly mosaic character of local environments. Bivalve burrows are very diversified, and several ichnogenera have been distinguished. Trace fossil producers as well as functional, taphonomic and preservational aspects of ichnofossils are discussed. The following ichnotaxa have been recognized: Lockeia siliquaria James, 1879; L. amygdaloides (Seilacher, 1953); L. czarnockii (Karaszewski, 1974); Scalichnus isp.; Scoyenia isp.; Spongeliomorpha isp.; Spongeliomorpha carlsbergi (Bromley and Asgaard, 1979); Cruziana problematica (Schindewolf, 1921); cf. Cruziana isp.; Rusophycus isp.; Diplichnites isp.; cf. Kouphichnium sp.; Planolites isp.; Palaeophycus isp.; Cochlichnus isp.; cf. Helminthoidichnites isp.; cf. Xylonichnus isp., and Linckichnus terebrans Schlirf, 2006. Various structures attributed to arthropod burrows (vertical to subvertical tunnels), chambered insect nests of Pallichnidae affinity or other nests with septa, earthworm burrows as well as enigmatic radial chambers, likely made by crayfishes, are illustrated. The new bivalve dwelling ichnotaxon Calceoformites uchmani igen. et isp. n. is described.
Źródło:
Volumina Jurassica; 2008, 6, 1; 109--132
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trace fossils from the Lower Jurassic Ciechocinek Formation, SW Poland
Autorzy:
Leonowicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/2061349.pdf
Data publikacji:
2008
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
trace fossils
fine-grained clastics
brackish environment
Lower Jurassic
Opis:
Mud-silt deposits of the Lower Jurassic Ciechocinek Formation from the Czestochowa-Wielun region are characterized by a low diversity ichnofossil association, which includes the ichnogenera Planolites, Palaeophycus, Helminthopsis, Gyrochorte, Protovirgularia and Spongeliomorpha as well as some unidentified pascichnia. This association points to deposition in a low-energy brackish environment with poorly oxygenated sediments. Changes of seafloor oxygenation, influenced by periodical bottom currents, resulted in various bioturbation intensities, which range from none to high.
Źródło:
Volumina Jurassica; 2008, 6, 1; 89-98
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neoichnology of an Arctic fluvial point bar, North Slope, Alaska (USA)
Autorzy:
Martin, A. J.
Powiązania:
https://bibliotekanauki.pl/articles/2059252.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
ichnofacies
polar
Scoyenia
Mermia
trace fossils
Opis:
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.
Źródło:
Geological Quarterly; 2009, 53, 4; 383-396
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 69

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies