Trace fossil assemblages reflecting stressed environments in the Middle Jurassic Carmel Seaway of central Utah

1999 ◽  
Vol 73 (4) ◽  
pp. 711-720 ◽  
Author(s):  
J. M. De Gibert ◽  
A. A. Ekdale
Keyword(s):  
Benthic Community ◽  
Middle Jurassic ◽  
Trace Fossils ◽  
Trace Fossil ◽  
Pore Waters ◽  
Shallow Marine ◽  
Marine Carbonate ◽  
Marine Carbonates ◽  
Low Diversity ◽  
Fossil Assemblages

The shallow-marine Carmel Formation (Middle Jurassic) in central Utah hosts low-diversity trace fossil assemblages, including Arenicolites, Chondrites, Gyrochorte, Lockeia, Planolites, Protovirgularia, Rosselia, Scalarituba, Skolithos, Taenidium, and Teichichnus. Non specialized ichnotaxa with a remarkably small burrow size dominate the assemblages. The amount of bioturbation is lower than expected in comparison with modern shallow-marine carbonate environments. These ichnological features also are significantly different from those of other Jurassic shallow-marine carbonates. The trace fossils represent an environmentally stressed benthic community in a marginal marine, restricted setting, with salinities above normal marine and with depletion of oxygen in pore waters.

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

Geologos ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 29-53 ◽  
Author(s):  
Alina Chrząstek ◽  
Monika Wypych
Keyword(s):  
Trace Fossils ◽  
Trace Fossil ◽  
Fair Weather ◽  
Soft Substrate ◽  
Southeastern Part ◽  
Shallow Marine ◽  
The North ◽  
Low Diversity ◽  
Storm Deposits ◽  
Interesting Compound

AbstractThe 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:Gyrochorteisp.,Ophiomorpha nodosaLundgren, 1891,Ophiomorphaisp.,Phycodescf.curvipalmatum(Pollard, 1981), ?Phycodesisp.,Planolitescf.beverleyensis(Billings, 1862),Thalassinoides paradoxicusWoodward, 1830 and ?Thalassinoidesisp. Moreover, interesting compound burrow systems, here referred to asThalassinoides-Phycodescf.palmatusand ?Thalassinoides-Phycodes, were recognised at the Czaple Quarry. Additionally, ?Gyrochorteisp.,Phycodescf.flabellum(Miller and Dyer, 1878) and ?Treptichnusisp. 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 gastropodNerinea bicinctaBronn, 1836 and the bivalveLima haidingeriZittel, 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,Gyrochorteand ?Treptichnus). The assemblage of trace fossils is characteristic of theSkolithosichnofacies andCruzianaichnofacies, 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.

New ichnofabrics of the Cenomanian–Danian Chalk Group

2020 ◽  
Vol 90 (7) ◽  
pp. 701-712
Author(s):  
Kasper H. Blinkenberg ◽  
Bodil W. Lauridsen ◽  
Dirk Knaust ◽  
Lars Stemmerik
Keyword(s):  
Trace Fossils ◽  
Trace Fossil ◽  
Shelf Area ◽  
Fine Grained ◽  
Fossil Assemblages ◽  
Facies Types ◽  
Body Fossil ◽  
Substrate Hardness ◽  
Nw Europe ◽  
Different Levels

ABSTRACT The Cenomanian–Danian Chalk Group of NW Europe is characterized by distinct trace-fossil assemblages dominated by Thalassinoides isp., Planolites isp., Zoophycos isp., and Chondrites isp., whereas ichnogenera such as Taenidium and Phycosiphon are rare. The trace fossils form a complex tiering arrangement, which reflects burrowing activities of diverse benthic associations that operate at different levels in the sediment column, dynamic sedimentation rates, and changes in substrate hardness during progressive burial, forming intricate ichnofabrics. In the Danish Basin, studies of chalk ichnofabrics have focused mainly on the Maastrichtian. Studies of the shallower, grain-rich Danian chalk have revealed similar trace-fossil assemblages, whereas the ichnology of the fine-grained, deeper-water Danian deposits is poorly known. Based on detailed facies and ichnofabric analysis of a mid-Danian silica-rich, pelagic chalk located in the central, deeper shelf area of the Danish Basin, four facies types, eight ichnotaxa, and two ichnofabrics are recognized. Most conspicuous and abundant are randomly distributed, variously sized meniscate burrows attributed to Bichordites isp. and Taenidium isp., whereas other common chalk trace fossils are rare or absent. This trace-fossil assemblage outlines two new ichnofabrics in the NW European chalk, which are dominated principally by upper-tier traces. The producer of the abundant Bichordites isp. and Taenidium isp. burrows is identified as a sea urchin on the basis of an exceptionally preserved Bichordites isp. trace aligned with an irregular echinoid body fossil. The identified ichnofabrics controlled early silicification and produced a more complex distribution of silica concretions compared with chalk successions elsewhere. This results in volumetrically thick silica concretion-rich units rather than distinctive silica bands as seen in other Upper Cretaceous and Danian chalk units.

Characterization and origin of permeability–porosity heterogeneity in shallow-marine carbonates: From core scale to 3D reservoir dimension (Middle Jurassic, Paris Basin, France)

2014 ◽  
Vol 57 ◽  
pp. 631-651 ◽  
Author(s):  
Benjamin Brigaud ◽  
Benoît Vincent ◽  
Christophe Durlet ◽  
Jean-François Deconinck ◽  
Emmanuel Jobard ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Paris Basin ◽  
Shallow Marine ◽  
Marine Carbonates ◽  
Porosity Heterogeneity

The Fish River Subgroup in Namibia: stratigraphy, depositional environments and the Proterozoic–Cambrian boundary problem revisited

2005 ◽  
Vol 142 (5) ◽  
pp. 465-498 ◽  
Author(s):  
G. GEYER
Keyword(s):  
Trace Fossils ◽  
Global Scale ◽  
Depositional Environments ◽  
Trace Fossil ◽  
Braided River ◽  
Shallow Marine ◽  
Sequence Stratigraphic ◽  
Marine Habitats ◽  
Short Period ◽  
Distinct Sequence

The Fish River Subgroup of the Nama Group, southern Namibia, is restudied in terms of lithostratigraphy and depositional environment. The study is based on partly fine-scaled sections, particularly of the Nababis and Gross Aub Formation. The results are generally in accordance with earlier studies. However, braided river deposits appear to be less widely distributed in the studied area, and a considerable part of the formations of the middle and upper subgroup apparently were deposited under shallowest marine conditions including upper shore-face. Evidence comes partly from sedimentary features and facies distribution, and partly from trace fossils, particularly Skolithos and the characteristic Trichophycus pedum. Environmental conditions represented by layers with T. pedum suggest that the producer favoured shallow marine habitats and transgressive regimes. The successions represent two deepening-upward sequences, both starting as fluvial (braided river) systems and ending as shallow marine tidally dominated environments. The first sequence includes the traditional Stockdale, Breckhorn and lower Nababis formations (Zamnarib Member). The second sequence includes the upper Nababis (Haribes Member) and Gross Aub formations. As a result, the Nababis and Gross Aub formations require emendation: a new formation including the Haribes and Rosenhof and possibly also the Deurstamp members. In addition, four distinct sequence stratigraphic units are deter-minable for the Fish River Subgroup in the southern part of the basin. The Proterozoic–Cambrian transition in southern Namibia is most probably located as low as the middle Schwarzrand Subgroup. The environmentally controlled occurrence of Trichophycus pedum undermines the local stratigraphic significance of this trace fossil which is eponymous with the lowest Cambrian and Phanerozoic trace fossil assemblage on a global scale. However, occurrences of such trace fossils have to be regarded as positive evidence for Phanerozoic age regardless of co-occurring body fossils. Other suggestions strongly dispute the concept of the formal Proterozoic–Cambrian and Precambrian–Phanerozoic boundary. Carbon isotope excursions and radiometric datings for the Nama Group do not help to calibrate precisely the temporal extent of the Fish River Subgroup. Fossil content, sequence stratigraphy and inferred depositional developments suggest that this subgroup represents only a short period of late orogenic molasse sedimentation during the early sub-trilobitic Early Cambrian.

scholarly journals Sedimentología e icnología de un delta fluvio-dominado, Formación Lajas (Jurásico Medio), cuenca Neuquina, Argentina

2020 ◽  
Vol 47 (1) ◽  
pp. 179 ◽  
Author(s):  
Nerina Canale ◽  
Juan José Ponce ◽  
Noelia B. Carmona ◽  
Martín N. Parada ◽  
Daniel I. Drittanti
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Middle Jurassic ◽  
Trace Fossils ◽  
Delta Front ◽  
Deformation Structures ◽  
Low Diversity ◽  
Channel Deposits ◽  
Channel Systems ◽  
Distributary Channel

Sedimentologic and ichnologic analysis of the Middle Jurassic Lajas Formation in Bajada de Los Molles area allow recognizing upper offshore-lower shoreface deposits in transition to prodelta, delta front and interdistributary bay succesions. This system is classified as a river-dominated delta due to the presence of distributary channel deposits with huge amounts of particulate organic matter and low diversity and abundance of trace fossils. Hyperpycnites are common in the basal and upper part of the studied section, and form channel-levee and distributary-channel systems, integrated by massive sandstones and load deformation structures, or transitional and recurrent passages of tractive sedimentary structures with abundant particulate organic matter on the foresets. The greatest diversity and abundance of trace fossils are recognized in the upper offshore-lower shoreface deposits where Skolithos and Cruziana ichnofacies occur. Deltaic deposits show trace fossil associations with lower diversity and abundance than the fully marine ones, whereas the hyperpycnite deposits are either unbioturbated or show the lowest diversity and abundance of trace fossils, reflecting the most stressed conditions within the system.

scholarly journals Paleoecologic and Biostratigraphic Significance of Trace Fossils From Shallow- to Marginal-Marine Environments From the Middle Cambrian (Stage 5) of Jordan

2012 ◽  
Vol 86 (6) ◽  
pp. 931-955 ◽  
Author(s):  
Richard Hofmann ◽  
M. Gabriela Mángano ◽  
Olaf Elicki ◽  
Rafie Shinaq
Keyword(s):  
Trace Fossils ◽  
Trace Fossil ◽  
Type Locality ◽  
Early Cambrian ◽  
Marine Environments ◽  
Middle Cambrian ◽  
Fossil Assemblages ◽  
Maximum Flooding Surface

The Hanneh Member (Cambrian Stage 5) of the Burj Formation and the Umm Ishrin Formation of Jordan represent a transgressive-regressive succession that contains twenty-eight ichnotaxa, including vertical burrows (Arenicolitesisp.,Diplocraterionisp.,Gyrolithes polonicus,Rosseliaisp.,Skolithos linearis, escape trace fossils), horizontal simple burrows and trails (Archaeonassa fossulata,Gordia marina,Helminthoidichnites tenuis,Palaeophycus tubularis,Planolites beverleyensis,P. montanus), plug-shaped burrows (Bergaueria sucta), horizontal branched burrows (Asterosomaisp.,Phycodesisp.,Treptichnuscf.T. pedum), bilobate structures (various ichnospecies ofCruzianaandRusophycus), and trackways and scratch marks (Diplichnitesisp.,Dimorphichnuscf.D. obliquus,Monomorphichnusisp.). Eleven trace-fossil assemblages are identified. TheArenicolitesisp. andDiplocraterionisp. assemblages occur in transgressive tidal dunes and bars whereas theRosseliaisp. assemblage characterizes areas between tidal dunes. TheCruziana salomonisassemblage reflects a wide variety of environmental settings including channels within tidal-bar complexes, bottomsets of tidal dunes, and interdune areas. TheGordia marinaassemblage is present between dune patches. TheGyrolithes polonicusassemblage penetrates into firmground mudstone below the maximum flooding surface. TheBergaueria sucta,Archaeonassa fossulata,Rusophycus aegypticusandCruziana problematicaassemblages occur in different subenvironments of the progradational delta.Cruziana salomonisandRusophycus burjensis, originally considered indicative of an early Cambrian age, are actually middle Cambrian in their type locality. Occurrences ofCruziana jordanicaandRusophycus aegypticusprovide evidence that these ichnospecies are of the same age in Jordan and may co-exist in terms of stratigraphic distribution withC. salomonisandR. burjensis.

scholarly journals Trace fossils and ichnofabric in the Kj0lby Gaard Marl, uppermost Cretaceous, Denmark

1983 ◽  
Vol 31 ◽  
pp. 107-119
Author(s):  
A. A. Ekdale ◽  
R. G. Bromley
Keyword(s):  
Trace Fossils ◽  
Trace Fossil ◽  
Depositional History ◽  
Major Phase ◽  
Sea Floor ◽  
Low Diversity ◽  
History Of ◽  
Basal Portion ◽  
Brown Clay

The Kj0lby Gaard Marl (Late Maastrichtian) is a 30 cm-thick, grayish brown, clay-rich, pelagic carbonate unit (75 to 85% CaCO3 ) exposed in the Limfjord region of northern Jylland, Denmark. Trace fossil suites and ichnofabric (the sedimentary fabric resulting from all phases of bioturbation) reflect a complex depositional and post-depositional history of the marl unit, which is sandwiched between comparatively pure chalk strata above and below. Initiation of marl deposition occurred gradually and episodically, as indicated by a micro-styolitic fabric resulting from solution-compaction of finely alternating chalk and clay laminae in the basal portion of the bed. During the major phase of marl deposition represented by the middle and upper parts of the unit, the sea floor apparently was very soft and was colonized by an active infauna which produced a low-diversity suite of trace fossils dominated by horizontal burrows. These are now preserved in a highly compacted ichnofabric which is totally bioturbated but contains no easily identifiable trace fossils. As the sedimentary mode returned to chalk deposition, the marl was buried and subsequently strengthened by compaction sufficiently to allow its colonization by a deeper-burrowing infauna that normally preferred somewhat stiffer, chalky substrates. Thus, the original ichnofat,ric was modified by the introduction of late-genera­tion, sharply defined and relatively uncompacted "chalk" trace fossils (Thalassinoides, Zoophycos and Chondrites, probably appearing in that order). These are superimposed directly on top of the earlier, highly deformed burrows of the initial trace fossil suite.

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