Diplocraterion Parallelum Research Articles

Palaeoenvironmental interpretation of the Late Cretaceous Idzików Conglomerate Member (SW Poland, Sudetes, Idzików Quarry) based on analysis of trace fossils

In the sandstones and conglomerates of the Idzików Conglomerate Member (Coniacian), exposed in the Idzików Quarry (SW Poland, Upper Nysa Kłodzka Graben), a moderately diverse assemblage of trace fossils has been recognized. The trace fossils include Arenicolites isp., Asterosoma isp., ? Bergaueria isp., Cylindrichnus isp., Conichnus conicus , Curvolithus simplex , Dactyloidites ottoi , Diplocraterion parallelum , ? Diplocraterion isp., Gyrochorte isp., Gyrophyllites aff. kwassizensis , Macaronichnus segregatis , Ophiomorpha nodosa , Ophiomorpha isp., ? Palaeophycus isp., ? Rhizocorallium isp., Rosselia isp., ?S colicia isp., Teichichnus isp. and Thalassinoides isp. Escape traces (fugichnia) and some unidentified trace fossils also were found. The following ichnoassociations are distinguished: (IA1) Ophiomorpha - Cylindrichnus , (IA2) Asterosoma - Conichnus and (IA3) Ophiomorpha-Arenicolites . IA1 probably represents a mixture of the impoverished proximal Cruziana ichnofacies and the distal Skolithos ichnofacies, which points to the lower, weakly storm-affected shoreface. IA2 is interpreted as the archetypal Skolithos ichnofacies (opportunistic colonization of tempestite beds) with some elements of the Cruziana ichnofacies (bioturbated, fair-weather background deposits) in the middle, moderately storm-affected shoreface. IA3 is assigned to the archetypal Skolithos ichnofacies, which indicates the upper shoreface-foreshore settings. The trace-fossil evidence implies that the Upper Cretaceous succession was deposited in a shallow, open basin with good oxygenation of the sea floor and normal salinity, under low- to moderately high-energy hydrodynamic conditions. On the basis of ichnological and sedimentological analyses, the deposits studied originated in a system of fan-delta and shallow-shelf settings with common transitional-proximal tempestites. They were deposited in the eastern part of the Upper Nysa Kłodzka Graben during the Coniacian regression.

Palaeoenvironmental Significance of Ichnofossil Assemblages from the Paleogene Sediments of Inner Fold Belt, Naga Hills, NE India

ABSTRACT Paleogene sediments of the inner fold belt, Naga hills, have very well preserved ichnofossils. 16 ichnospecies have been documented among 13 ichnogenera such as Arenicolites isp., Chondrites targionii, Cylindrichnus isp., Diplocraterion parallelum, Gyrochorte isp., Ophiomorpha annulata, O. irregulaire, O. nodosa, O. rudis, Palaeophycus tubularis, Planolites beverleyensis, Scolicia palaeobullia, Skolithos linearis, Trypinites weisei, Thalassinoides horizontalis and Zoophycos isp. The ichnofossil assemblages comprise mostly domichnia and fodinichnia benthos of the Skolithos and Cruziana ichnofacies. A shallow marine nearshore to offshore marine environment with fluctuating energy condition has been envisaged.

PREFERENTIAL ORIENTATION OF SHRIMP-GENERATED DIPLOCRATERION PARALLELUM AND THEIR RELIABILITY AS PALEOCURRENT INDICATORS

Arthropods from the late Campanian (Late Cretaceous) of the Western Interior Seaway produced U-shaped Diplocraterion parallelum in mudstones along two closely spaced surfaces (10 cm apart), one of which corresponds to a maximum transgressive surface. Diplocraterion parallelum are widely distributed across both surfaces, with substantial variations in burrow orientations. Based on a comparison of paleocurrent indicators to burrow orientations, we demonstrate that D. parallelum are preferentially oriented parallel to the prevailing fair-weather wave propagation direction (wave-forced currents) that acted upon the colonized surfaces. There is an apparent maximum (34% above uniformity) preferential orientation of the burrows, attributed to the fact that wave-forced currents represent only one of several factors controlling shrimp burrowing behaviors. Based on this study, we propose that in the absence of paleocurrent data, Diplocraterion and other U-shaped burrows can be used to resolve flow directions, and that preferential burrow orientations ≥ 2% above uniformity are significant. However, it is noted that it is only possible to resolve 2-way flow directions (trend) from U-shaped burrows, as there is no way to determine vector directions.

Ichnologic evidence of a Cambrian age in the southern Amazon Craton: Implications for the onset of the Western Gondwana history

Colonization of the infaunal ecospace by burrowing bilaterians is one of the most important behavioral innovations during the Ediacaran-Cambrian transition. The establishment of vertical burrows by suspension feeders in high-energy nearshore settings during Cambrian Age 2 is reflected by the appearance of the Skolithos Ichnofacies. For the first time, unquestionable vertical burrows typical of the Skolithos Ichnofacies, such as Skolithos linearis, Diplocraterion parallelum and Arenicolites isp., are recorded from nearshore siliciclastic deposits of the Raizama Formation, southeastern Amazon Craton, Brazil. Integration of ichnologic and sedimentologic datasets suggests that these trace fossils record colonization of high-energy and well-oxygenated nearshore sandy environments. Chronostratigraphically, the presence of these vertical burrows indicates an age not older than early Cambrian for the Raizama Formation, which traditionally has been regarded as Ediacaran. Therefore, the Raizama ichnofauna illustrates the advent of modern Phanerozoic ecology marked by the Agronomic Revolution. The discovery of the Skolithos Ichnofacies in these shallow-marine strata suggests possible connections between some central Western Gondwana basins.

ICHNOFOSILIE MYSLEJOVICKÉHO SOUVRSTVÍ DRAHANSKÉHO KULMU (SPODNÍ KARBON, MORAVSKOSLEZSKÁ JEDNOTKA ČESKÉHO MASIVU)

The research in this study is focused on trace fossils of the Myslejovice Formation, which is one of the lithostratigraphical units in the Lower Carboniferous sequences of the Drahany Culm Basin that belongs to the large area of Rhenohercynian Zone of the Variscan orogenetic flysch belt. Ichnofossils have mainly been collected in the southeastern part, near Vyškov. The material comes from the collection of Mr. Veleslav Lang which is nowadays stored in the Regional Museum of Olomouc. From this collection total 615 specimens in 10 ichnogenera and 13 following ichnospecies were determined and redefi ned: ?Alcyonidiopsis isp., Cosmorhaphe isp., Dictyodora liebeana, Diplocraterion parallelum, Gordia isp., Chondrites cf. intricatus, Chondrites isp., Nereites missouriensis, Nereites isp., Phycosiphon incertum, Planolites beverleyensis, Planolites isp. and Rhizocorallium isp. The revised material comes from the following locations: Opatovice, Habrovany, Hamiltony, Ježkovice, Lhota, Luleč, Myslejovice, Nemojany – Blatická dolina, Nemojany, Otaslavice, Pístovice, Radslavice and Rychtářov. The overall character of ichnoassemblages indicates conditions of Nereites ichnofacies, which is typical for the distal parts of the suprafan turbidite lobes. Compared to other areas of Culm facies in Middle Europe, assemblages of the Myslejovice Formation belong among the less diversified.

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

Shallow-marine deposits, included in the “Basal Sands” of the Eocene Pauji 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 Motatan 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.

Variations in population structure of Diplocraterion parallelum: Hydrodynamic influence, food availability, or nursery settlement?

In the Triassic of the Betic Cordillera, the U-shaped trace fossil Diplocraterion parallelum exhibits pronounced spatial variations in its abundance, size, and orientation. Higher density populations are found in small patches on bedding planes that were topographic lows on the palaeo-seafloor. These patches consist mainly of small specimens, separated into two size-groups: group A with larger specimens, and a similar preferred orientation, and group B of smaller individuals, densely distributed, and with a more variable orientation.Between the patches, isolated large individuals occur sparsely. Comparison with populations of crustaceans (which are among the potential trace makers of Diplocraterion parallelum) allows possible population dynamics of D. parallelum trace makers in this setting to be considered. Important factors determining changes in the abundance and distribution of crustacean populations are protection of small individuals against predators and/or comparatively high-energy conditions, nursery settlement, and/or temporal, typically seasonal, variations in environmental parameters. Depressions of the seafloor appear to have represented hospitable habitats in which juveniles of the producer of D. parallelum developed, reflecting either a deliberate reproductive strategy or the consequence of accumulation of eggs deposited elsewhere. In these depressions energy conditions may have been lower and food availability higher. During early ontogeny, defenseless young individuals used these areas as an ecological refuge against predators and high energy conditions. When the juveniles of the D. parallelum trace makers grew, they presumably spread from the nursery to settle in the surrounding area.

Skolithospipe rock and associated ichnofabrics from the southern Rocky Mountains, Canada: colonization trends and environmental controls in an early Cambrian sand-sheet complex

Desjardins, P.R., Mangano, M.G., Buatois, L.A. & Pratt, B.R. 2010: Skolithos pipe rock and associated ichnofabrics from the southern Rocky Mountains, Canada: colonization trends and environmental controls in an early Cambrian sand-sheet complex. Lethaia, 10.1111/j.1502-3931.2009.00214.x The Lower Cambrian Gog Group of the southern Rocky Mountains of western Canada offers an opportunity to explore animal–sediment relationships in a high-energy setting, during the early phase of Phanerozoic diversification. Its strata record a sand-sheet complex on the broad pericontinental shelf of West Laurentia. Six ichnofabrics are recognized: Skolithos IF-1 characterized by Skolithos linearis in planar cross-stratified sandstone; Skolithos IF-2 with Skolithos linearis and accessory Diplocraterion parallelum in ripple cross-laminated, and planar and trough cross-stratified sandstone; Skolithos IF-3 with S. linearis and Planolites montanus in wavy- and flaser-bedded sandstone, interfingering with bioturbated mudstone exhibiting P. montanus and Teichichnus rectus; Skolithos IF-4, characterized by abundant Skolithos linearis in planar and trough cross-stratified sandstone; Rosselia IF-1 consisting of Rosselia isp. in planar cross-stratified sandstone; and Rosselia IF-2 consisting of scattered small Rosselia isp. in hummocky, cross-stratified sandstone. The presence of contrasting ichnofabrics within a single early Cambrian sand-sheet complex illuminates how the colonization trends of suspension and detritus feeders were controlled by factors specific to the various sub-environments. □Gog Group, Ichnofabric, Lower Cambrian, Pipe Rock, Rosselia, Skolithos.

Devonian Trace Fossils of the Horlick Formation, Ohio Range, Antarctica: Systematic Description and Palaeoenvironmental Interpretation

The clastic Horlick Formation contains an ichnofauna of 28 ichnotaxa dominated by burrowers. These are a mixture of simple vertical forms (Skolithos linearis, S. magnus, Bergaueria cf. langi, Rosselia socialis, Monocraterion isp.), U or arc-like forms (Diplocraterion parallelum, Arenicolites types A and B, Catenarichnus antarcticus, C. isp., aff. Lanicoidichna isp.), and complex, vertical spiral structures (Asterosoma isp., Spirophyton isp.). Horizontal burrows include Ancorichnus cf. capronus, Palaeophycus tubularis, and Psammichnites devonicus isp. nov. Surface traces comprise Haplotichnus isp., Cruziana problematica, C. rhenana, Rusophycus aff. carbonarius, R. isp., Protovirgularia rugosa, Lockeia ornata and cubichnia indet., while trackways include Diplichnites gouldi, D. isp., Maculichna? isp. and large imprints. The Horlick Formation (maximum 56 m) records an early Devonian transgression onto a deeply weathered land area that lay in the direction of Marie Byrd Land, spreading from the South Africa sector of Gondwana. Analysis of the trace fossils confirms their formation in near-shore to intertidal environments, with some ichnotaxa living close to the marine/fluvial boundary (e.g., Spirophyton, aff. Lanicoidichna, Cruziana problematica, Rusophycus aff. carbonarius, Maculichna?). The ichnofauna probably comprised a variety of marine suspension and deposit-feeding worms, shallow burrowing molluscs (bivalves and possibly bellerophontids) and several different types of arthropods, including trilobites.

Diplocraterion parallelum Torell, 1870, and other trace fossils from the Lower Triassic succession of the Drienok Nappe in the Western Carpathians, Slovakia

Diplocraterion parallelum Torell, 1870, and other trace fossils from the Lower Triassic succession of the Drienok Nappe in the Western Carpathians, Slovakia

Lateral variability in shallow marine ichnofabrics: implications for the ichnofabric analysis method

Ichnological analysis, commonly undertaken both in the field and in core studies, is generally carried out in vertical logged successions. This work documents the results of a detailed ichnofabric study of two highly bioturbated sandstone beds separated by a mudstone, within the thick, Lower Jurassic succession of the Yorkshire coast, UK. The two sandstone beds contain relicts of hummocky cross-stratification and rare bioclasts of bivalves and belemnites. Bioturbation of the beds is intense and the diversity of trace fossils is considerable. Trace fossils present include Teichichnus rectus , Teichichnus isp. A, Thalassinoides isp., Palaeophycus heberti , Diplocraterion parallelum , Rhizocorallium , Rosselia socialis , Schaubcylindrichnus isp., Chondrites isp., Planolites isp. and Phycosiphon incertum . Ichnofabrics were studied at 5 m intervals parallel to the modern cliff-line, which is parallel to the inferred Jurassic palaeo-coastline. The results demonstrate that there is considerable patchiness to ichnofabric even in a comparatively simple depositional setting such as a storm-influenced shelf. This observation is in line with studies of the modern sea floor. The implications of patchiness in ichnofabric are broad-ranging, but most importantly suggest that caution is needed in the use of ichnofabric analysis for intra-regional correlations.

Trace fossils and pseudofossils from the Wealden strata (non-marine Lower Cretaceous) of southern England

The trace fossils of the Wealden (non-marine Lower Cretaceous) of southern England are described. Sixteen invertebrate ichnotaxa include Agrichnium fimbriatus, Beaconites antarcticus, B. barretti, Cochlichnus anguineus, Diplichnites triassicus, Diplocraterion parallelum, Lockeia siliquaria, L. serialis, Monocraterion cf. tentaculum, Palaeophycus striatus, P. tubularis, Planolites montanus, Protovirgularia rugosa, Rhizocorallium isp., Scoyenia cf. gracilis, Unisulcus minutus, insect and root traces. Tetrapod tracks and trackways include tridactyl Iguanodontipus burreyi and other ornithopods, theropod, and tetradactyl sauropod (or possibly ankylosaur), together with extensive dinosaur tramplings. Coprolites are referred to two broad types: spiral, with or without included fish scales (attributable to sharks), and elongate and irregular (possibly produced by reptiles). A skinprint and two types of pseudofossil are also included. Five environmental associations are recognised: (1) lacustrine/lagoonal; (2) brackish incursions (flooding events) into the lacustrine/lagoonal environment; (3) a marginal lacustrine association with fluvial input; (4) a fluvial (lacustrine delta) association; (5) floodplain sediments (seasonal wetlands). These associations are assigned to the fluvial-lacustrine Scoyenia Ichnofacies and the incursions to Glossifungites Ichnofacies.

Diplocraterion: A Useful Marker for Sequence Stratigraphy and Correlation in the Kimmeridgian, Jurassic (Prebetic Zone, Betic Cordillera, southern Spain)

Abstract Diplocraterion parallelum with exclusively protrusive spreite are documented at particular horizons in fine-grained Lower Kimmeridgian (Upper Jurassic) deposits from the Prebetic Zone (Betic Cordillera, southern Spain). The occurrence of D. parallelum and the interpreted change from a Cruziana ichnofacies to a mixed Skolithos-Cruziana assemblage is related to increasing energy and more proximal and unstable substrates resulting from relative sea-level falls. These relative sea-level changes agree with a proposed Type-II sequence boundary inferred from sequence stratigraphic analysis. Bio-chronostratigraphic control shows the persistent occurrence of Diplocraterion close to the Platynota/Hypselocyclum Zone boundary (Lower Kimmeridgian); that is, these occurrences correlate between sections irrespective of slight deviations in the sedimentary package. Thus, Diplocraterion occurrence is proposed as a reference level for stratigraphy within epicontinental deposits of the northern margin of the wester...

Environmental distribution of trace fossils in the Jurassic of Kachchh (Western India)

Trace fossils occur abundantly in Middle Jurassic rocks of the Kachchh Basin. They are found in environments ranging from beach sequences down to central parts of the basin. For stratinomic reasons, they are particularly well preserved in storm deposits. Their distribution pattern exhibits a clear relationship to the hydrodynamic conditions and, secondarily, to bathymetry, and follows the classic ichnofacies concept ofSeilacher (1967). High energy nearshore areas and submarine shoals are represented by members of the Skolithos ichnofacies such asOphiomorpha nodosa, Arenicolites, Diplocraterion parallelum, andRhizocorallium jenense. The storm-influenced ramp contains both members of the Cruziana ichnofacies (e.g.Rhizocorallium irregulare, Thalassinoides suevicus, Taenidium serpentinum, Chondrites) and the Skolithos ichnofacies (in particularOphiomorpha). The former were produced during interstorm phases, the latter are of post-storm origin. Carbonate ramp environments of low to intermediate energy also contain members of the Cruziana ichnofacies, whilst equivalent siliciclastic environments are characterized by a low-diversity Zoophycos ichnofacies. Low energy basinal environments of fine-grained substrates contain an impoverished Cruziana ichnofacies consisting ofChondrites, Trichichnus andThalassinoides suevicus.

The ichnology of a submarine braided channel complex: the Whisky Bay Formation, Cretaceous of James Ross Island, Antarctica

Cretaceous rocks of the Whisky Bay Formation in northwest James Ross Island, Antarctica are described in terms of lithology, bed geometry, fabric, sedimentary structures and trace fossils. They are interpreted as a braided submarine channel complex in the inner part of a submarine fan. Nine lithofacies grouped in four lithofacies associations are defined. Major braided channel association is characterized by gravelly turbidity current and debris flow deposits. Terrace and minor braided channel association records the action of high density gravelly and sandy turbidity currents. Sandy plain association may represent deposition by “classical” turbidity currents. Interchannel area association evidences low density turbidity currents and suspension sedimentation, far away from channel processes. A brief description of trace fossils present in the unit is given and environmental implications of their distribution are emphasized. Arenicolites isp., Diplocraterion parallelum, Palaeophycus tubularis, Planolites cf. P. ophthalmoides, Skolithos linearis and Thalassinoides suevicus make up the ichnocoenosis A. It mainly represents dwelling-feeding structures (Domichnia) of suspension feeders in minor channels, marginal terraces and sandy proximal plains. The presence of these “shallow-water” traces is related to local conditions (high energy, sandy substrate, intermittent oxygenation and slow build up of organic detritus), rather than bathymetry. Cylindrichnus concentricus, Chondrites isp. and Zoophycos isp. (large and small form) make up the ichnocoenosis B. It is composed of deep deposit-feeders feeding structures (Fodinichnia) in interchannel areas. Ethologic group Agrichnia is completely absent. The ichnocoenosis B is anomalous in submarine fans. The dynamics associated with the coarse-grained inner channelized part of this submarine fan are a precluding factor in the development of highly specialized traces. The replacement of an Agrichnia and Pascichnia-dominated trace fossil assemblage (typical from submarine fans) by the Fodinichnia-dominated ichnocoenosis B is considered a result of the combination of different related factors. Probably contemporaneous volcanic activity originated frequent sediment gravity flows that introduced considerable amounts of organic material into the system. It is suggested that the analysed deposits were formed close to the source area at shallower depths than normal submarine fans. As a result of this particular depositional setting, an abnormal development of feeding opportunistic trace fossils took place. Conversely, the existence and evolution of more complicated and specialized graphoglyptid patterns of trace fossils was inhibited in these organic-rich sediments deposited in such an unstable setting.

The growth vector in trace fossils: Examples from the Lower Cambrian of Norway

The Dividal Group of northern Norway includes both Vendian and Lower Cambrian sequences. Trace fossil assemblages in the Lower Cambrian part of the group generally indicate endobenthic communities dominated by deposit‐feeding animals. At one level, however, an unusual succession of trace fossils occurs that includes Diplocraterion parallelum and a conical, branching shaft herewith named Altichnus foeyni. Both forms show features recording the growth of the tracemaking animals. Suspension feeders are probably indicated. D. parallelum is exclusively protrusive, which is suggested to be a primitive behavioral feature. The trace fossil also shows random orientation; well‐developed parallel orientation of D. parallelum does not seem to have been recorded before the Triassic. This assemblage represents the earliest documented example of the Glossifungites ichnofacies.

Trace fossils and paleoenvironmental control of ichnofacies in a late Quaternary gravel and loess fan delta complex, New Zealand

Remarkably well-preserved trace fossil assemblages of a small, Late Quaternary (> 3000 yr B.P.) fan delta complex are exposed in sea cliffs south of Conway Flat, North Canterbury, New Zealand. Marine trace fossils are common and well-preserved in the bar, embayment and prodelta facies, but deltaic distributary facies contain no trace fossils at all. The preceding paper in this journal ( Lewis and Ekdale, 1991) describes the lithofacies and their paleoenvironmental setting in this fan delta complex. Common trace fossils include the ichnogenera Anconichnus, Arenicolites, Asterosoma, Cylindrichnus, Diplocraterion, Gordia, Helminthoida, Ophiomorpha, Piscichnus, Planolites and Skolithos. One new ichnogenus ( Arborichnus), two new ichnospecies ( Arborichnus sparsus and Diplocraterion asymmetrium), and three informal varieties of Diplocraterion parallelum (var. lingum, arcum and quadrum) are introduced. Local ichnofacies include (a) low-divsity Anconichnus horizontalis Ichnofacies of densely packed burrows of deposit-feeding animals in shallow-marine, fine-grained sediment of bar and distal embayment facies, (b) high-diversity Diplocraterion parallelum var. lingum Ichnofacies of burrows of suspension-feeding animals in interbedded mud, clean sand and gravelly sand of the bar facies, (c) moderate-diversity Diplocraterion parallelum var. quadrum Ichnofacies in interbedded mud and sand of distal embayment facies, and (d) low-diversity Planolites montanus Ichnofacies of deformed burrows in bioturbated mud of the prodelta facies. In addition, sparse animal escape structures (fugichnia) occur locally in interbedded sand and gravel of the bar facies. The trace fossil associations of the Conway Flat fan delta complex are unusual in their excellent state of preservation, and many trace fossils are exposed in full-three-dimensional relief. Because of their very young age, they must reflect similar associations of biogenic sedimentary structures in modern deltaic settings that are as yet undescribed. This report appears to be the first documentation of a fully marine trace fossil assemblage in loessial sediments.

Palaeoenvironmental significance of trace fossils from the shallow marine Lower Jurassic Neill Klinter Formation, East Greenland

The shallow marine deposits of the Lower Jurassic Neill Klinter Formation of East Greenland contain a diverse assemblage of well-preserved trace fossils. Thirty-four ichnotaxa are distributed among 11 different ichnocoenoses, characterized by Diplocraterion habichi, Diplocraterion parallelum, Arenicolites isp. 1, Arenicolites isp. 2, Cochlichnus, Curvolithos, Taenidium, Ophiomorpha, Rhizocorallium, Phoebichnus and Planolites. The ichnocoenoses are interpreted in the light of their trophic and ethological properties and show a strong correlation with the sedimentary environments. Their distribution reflects changes in factors controlled by water depth and bottom water oxygenation. Evidence fo opportunitic recolonization following major environmental changes has also been preserved. The Diplocraterion paralellum ichnocoenosis occurs typically in foreshore and shoreface environments as well as tidal sandwave field environments on the inner shelf. Together with Diplocraterion habichi ichnocoenosis it also characterizes transgressive surfaces where they form omission suites. The Cochlichnus ichnocoenosis has the highest diversity and is characteristic of tidally-influenced rippled inner shelf environments. The Phoebichnus ichnocoenosis occurs in oxygen-limited shelf environments that were exploited thoroughly by a population of opportunistic organisms. The Curvolithos ichnoceonosis occurs in the distal portion of subaqueous fan delta environments and in open shelf settings and the Arenicolites isp. 2 ichnocoenoesis in the proximal portion of subaqueous fan delta environments. The Planolites, Rhizocorallium, Taenidium, Ophiomorpha and Arenicolites isp. 1 ichonocoenoses are characteristic of storm-dominated shelf environments. The ichnocoenoses of the Neill Klinter Formation are taxonomically identical, or nearly so, to the trace fossil assemblages of other marine Jurassic and Lower Cretaceous sandstones of East Greenland. They often occur in similar lithofacies, which underlines their use in palaeoenvironmental interpretations.

Trace Fossils and Bioturbation in Peritidal Facies of the Potsdam-Theresa Formations (Cambrian-Ordovician), Northwest Adirondacks

The Cambrian-Ordovician Potsdam Sandstone, Theresa Formation, and Canadian correlatives in the St. Lawrence Lowlands preserve tide-dominated facies during the basal Cambrian transgression. Low intertidal sand flats in the upper Potsdam contain a Skolithos Ichnofacies dominated by Diplocraterion parallelum in clean, herringbone cross-bedded sandstones indicative of high tidal current energy. Wind-wave-driven longshore and tidal currents along a macrotidal coastline were funneled northeast-southwest by Precambrian topographic relief of up to 65 m. This relief is now expressed as the Thousand Islands of New York and Canada. The conformably overlying Theresa Formation preserves a shoaling-upward sequence of mixed clastic-carbonate facies. Shallow subtidal and peritidal facies contain a mixed Skolithos-Cruziana Ichnofacies in sharply alternating lithofacies consisting of gray, intensely bioturbated, poorly sorted calcareous sandstone, and meter-thick, white cross-bedded sandstone. The parallelism between ichnofacies and lithofacies indicates that environmental energy level and persistence rather than water depth controlled trace fossil distribution. Bioturbated sandstones contain a Cruziana ichnofacies of abundant deposit feeders including: Fustiglyphus , Gyrochorte , Neonereites uniserialis , Phycodes flabellum, Planolites beverlyensis, Rosselia socialis, and Teichichnus. Suspension feeders are represented by D. habichi, D. parallelum, Skolithos, Monocraterion, and possibly Palaeophycus tubularis. Scavenging or deposit-feeding arthropods are represented by rare Cruziana furrows. Cross-bedded sandstones containmore » a Skolithos Ichnofacies of shallow Skolithos and Monocraterion burrows, and an undescribed large epistratal eurypterid( ) trail.« less

The Trace-Fossil Diplocraterion: Evidence of Animal-Sediment Interactions in Cambrian Tidal Deposits

The U-shaped, spreiten-bearing burrows Diplocraterion parallelum and D. habichi in the Hickory Sandstone Member of the Riley Formation (Cambrian), record interactions with other metazoans and the substrate, thus revealing paleoecologic, sedimentologic, and environmental details about this basaltransgressive, cratonic sandstone in central Texas. These trace fossils establish the presence of a low-level suspension-feeding, infaunal trophic group not found in the Hickory Sandstone body-fossil record. Diplocraterion probably represents the activity of infaunal, suspension-feeding invertebrates. The Diplocraterion burrow depth of 19.5 cm is additional evidence for a Cambrian suspension-feeding tier deeper than previously estimated. Skolithos/Monocraterion rarely occur in facies with abundant Diplocraterion. High ambient water temperatures may have been a factor controlling the distribution of the organisms within the Diplocraterion-Skolithos/Monocraterion trophic group. The protrusive behavior (downward motion) of Diplocraterion resulted from the interaction with current flow of a high-density tube field of suspension feeders. This interaction caused turbulent eddies to impinge on the bed, resulting in current scour of the substrate. Sediment sorting within the Hickoty may have been a direct result of the reworking of vast tidal sand flats by infauna, aiding already strong tidal currents in removing mud-sized particles. Diplocraterion is a diagnostic marine trace fossil and can be used to separate nonmarine from marine environments in basal Paleozoic, cratonic sandstones. It is useful in identifying tidally influenced environments when found in facies resulting from high-energy deposition.