scholarly journals CHONDRITES-CLADICHNUS ICHNOCOENOSIS FROM THE DEEP-SEA DEPOSITS OF PIERFRANCESCO (CRETACEOUS; ITALY): OXYGEN- OR NUTRIENT-LIMITED?

2022 ◽  
Vol 128 (1) ◽  
Author(s):  
ANDREA BAUCON ◽  
GIROLAMO LO RUSSO ◽  
CARLOS NETO DE CARVALHO ◽  
FABRIZIO FELLETTI
Keyword(s):  
Late Cretaceous ◽  
Deep Sea ◽  
Trace Fossils ◽  
Northern Apennines ◽  
Trace Fossil ◽  
Ecological Succession ◽  
Rhythmic Pattern ◽  
Low Oxygen ◽  
Fossil Assemblage

The Italian Northern Apennines are acknowledged as the place where ichnology was born, but there is comparatively little work about their ichnological record. This study bridges this gap by describing two new ichnosites from the locality of Pierfrancesco, which preserve an abundant, low-disparity trace-fossil assemblage within the Late Cretaceous beds of the M. Cassio Flysch. Results show that lithofacies and ichnotaxa are rhythmically organized. The base of each cycle consists of Megagrapton-bearing calciclastic turbidites, which are overlain by marlstone beds with an abundant, low-disparity assemblage of trace fossils. This includes Chondrites intricatus, C. patulus, C. targionii, C. recurvus and Cladichnus fischeri. The cycle top consists of mudstones with no distinct burrows. The rhythmic pattern of Pierfrancesco reflects a deep-sea ecological succession, in which species and behaviour changed as turbidite-related disturbances altered the seafloor. This study opens the question of whether the Chondrites-Cladichnus ichnocoenosis represents low-oxygen or nutrient-poor settings.

Devonian depositional environments in the Darwin Mountains: Marine or non-marine?

1993 ◽  
Vol 5 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Ken J. Woolfe
Keyword(s):  
Fresh Water ◽  
Depositional Environment ◽  
Trace Fossils ◽  
Depositional Environments ◽  
Trace Fossil ◽  
Glacier Area ◽  
Red Beds ◽  
Fossil Assemblage ◽  
Considerable Debate

The depositional environment of the Devonian Taylor Group has been subject to considerable debate for over 30 years. The debate stems largely from a belief that the abundant and diverse trace fossils represent a marine ichnofauna, whereas sedimentary features, including palaeosols, desiccation polygons and red beds, are more typical of a non-marine setting. The debate is reconciled by a reinterpretation of the trace fossil assemblage which shows that the trace fossils comprise a typical fresh water (Scoyenia ichnofacies) assemblage, and their occurrence in the Taylor Group in the Darwin Glacier area is entirely consistent with deposition in a mixed fluvial-lacustrine-subaerial environment.

Rhizocorallium and turtle tracks: a late Cretaceous proximal distributary channel trace-fossil assemblage, central Utah

Ichnos ◽  
2020 ◽  
Vol 27 (4) ◽  
pp. 406-427
Author(s):  
M. Ryan King ◽  
Scott E. Botterill ◽  
Murray K. Gingras ◽  
S. George Pemberton
Keyword(s):  
Late Cretaceous ◽  
Trace Fossil ◽  
Fossil Assemblage ◽  
Distributary Channel

Trace fossils from Lower Palaeozoic ocean-floor sediments of the Southern Uplands of Scotland

1982 ◽  
Vol 73 (2) ◽  
pp. 67-87 ◽  
Author(s):  
M. J. Benton
Keyword(s):  
Oxygen Content ◽  
Deep Sea ◽  
Trace Fossils ◽  
Trace Fossil ◽  
Ocean Floor ◽  
Turbidity Currents ◽  
Northern Margin ◽  
Iapetus Ocean ◽  
Lower Palaeozoic

ABSTRACTThe Ordovician and Silurian rocks of the Southern Uplands of Scotland have been interpreted as sediments deposited on the northern margin of the Iapetus Ocean. Trace fossils are abundant at many localities in ocean-floor turbidites and mudstones that usually lack all other evidence of life. Twelve ichnogenera are present, and they are mainly meandering locomotion and feeding trails and burrow networks: Dictyodora, Caridolites, Helminthoida, Neonereites, Nereites, Protovirgularia, Gordia, Megagrapton, Paleodictyon, Chondrites, Plano-lites and Skolithos. The trace fossils occur in at least five distinct assemblages and the composition of these was probably controlled by the frequency and nature of the turbidity currents, and possibly by the oxygen content of the mudstones. Where turbidity currents were weak, abundant Dictyodora, together with Caridolites, Neonereites, Nereites, Protovirgularia and Gordia occur in various combinations. Where currents were stronger, traces such as Gordia, Paleodictyon and Megagrapton may be exhumed and cast on turbidite soles, and the sand may contain Skolithos. The ‘deep-sea’ Nereites trace fossil facies is divisible into several assemblages, presumably environmentally controlled.

The evolutionary significance of a Lower Cambrian trace-fossil assemblage from the Meguma terrane, Nova Scotia

2011 ◽  
Vol 48 (1) ◽  
pp. 71-85 ◽  
Author(s):  
Murray K. Gingras ◽  
John W.F. Waldron ◽  
Chris E. White ◽  
Sandra M. Barr
Keyword(s):  
Nova Scotia ◽  
Lower Cambrian ◽  
Trace Fossils ◽  
Trace Fossil ◽  
Evolutionary Significance ◽  
Fossil Assemblage ◽  
Approximate Order ◽  
Meguma Terrane ◽  
Wrinkle Structures ◽  
Fossil Preservation

We report a diverse assemblage of trace fossils from the Lower(?) Cambrian High Head member of the Church Point Formation near Yarmouth, Nova Scotia. Based on the presence of sharp-based beds, load casts, and flute casts, along with other sedimentological criteria, the strata are interpreted to have a turbidite origin. Other characteristics, including wrinkle structures and high fidelity of trace-fossil preservation, suggest that the inter-episode biotope was influenced by the presence of biomats. The trace-fossil assemblage includes (in approximate order of abundance) Planolites , Helminthopsis , Oldhamia , Chondrites , Gordia , Cladichnus , Psammichnites gigas , Treptichnus , Phycodes , Lorenzinia , Palaeophycus , and Teichichnus . Trace fossils are increasingly abundant upwards in the section, but they are ultimately mitigated by an increase in (inferred) sedimentation rates. The trace-fossil assemblage, which bears many similarities to other Lower Cambrian locales (e.g., Puncoviscana Formation of northwest Argentina, Chapel Island Formation of southeastern Newfoundland), and the distribution of ichnofossils strongly support an earliest Cambrian age for the studied strata. More importantly, evolutionary trends can be interpreted from the trace-fossil assemblage, namely (1) an increase in size and diversity of animals in deep water; (2) an expansion of motile strategies used to coexist with biomats; and, (3) increasingly complex mining strategies below the sediment-biomat interface.

scholarly journals Asteriacites and other trace fossils from the Po Formation (Visean–Serpukhovian), Ganmachidam Hill, Spiti Valley (Himalaya) and its paleoenvironmental significance

2017 ◽  
Vol 68 (5) ◽  
pp. 464-478 ◽  
Author(s):  
Birendra P. Singh ◽  
Om N. Bhargava ◽  
Radek Mikuláš ◽  
Subhay K. Prasad ◽  
Garry Singla ◽  
...  
Keyword(s):  
Trace Fossils ◽  
Trace Fossil ◽  
Fossil Assemblage ◽  
Sedimentary Structures ◽  
The Village ◽  
The Himalaya ◽  
Open Shelf

Abstract An assemblage of trace fossils comprising Asteriacites stelliformis, A. quinquefolius, Biformites insolitus, Helminthoidichnites? isp., Lingulichnus isp., Lockeia siliquaria, Palaeophycus tubularis, Planolites isp., Protovirgularia isp. A, Protovirgularia isp. B, Protovirgularia isp. C, Psammichnites isp., Rusophycus isp., and Treptichnus isp. from the Po Formation (Visean-Serpukhovian) exposed along the base of Ganmachidam Hill near the village of Chichong, Spiti Valley in the Himalaya, is described. Storm beds (tempestites) are highly bioturbated. Sedimentary structures such as hummocky cross-stratification (HCS), low-angle planar and trough cross beds, and shallow, slightly asymmetrical gutter casts are observed. The overall trace fossil assemblage indicates the presence of upper shoreface to lower shoreface Cruziana ichnofacies of an open shelf.

scholarly journals Paleoecologic aspects of ichnofabrics (biogenic sedimentary fabrics) in deep-sea sediment

1992 ◽  
Vol 6 ◽  
pp. 91-91
Author(s):  
A. A. Ekdale
Keyword(s):  
Late Cretaceous ◽  
Deep Sea ◽  
Fossil Record ◽  
Trace Fossil ◽  
Interstitial Oxygen ◽  
Macroinvertebrate Communities ◽  
Sea Floor ◽  
Infaunal Community ◽  
Early Tertiary ◽  
Shelf Sea

The paleoecology of deep-sea, benthic, macroinvertebrate communities is largely confined to the trace fossil record. While a few taxa have preservable hard parts, most of the deep-sea macrofauna are unpreservable as body fossils below the aragonite or calcite compensation depths. The ichnologic record provides important synecologic information regarding the behavioral diversity and endobenthic habitat partitioning of at least some community members.The deep-sea trace fossil record is strongly influenced by sediment composition (biogenic calcite vs. terrigenous clay), sedimentation regime (pelagic vs. turbidite deposition) and bioturbation history (continuous vs. discontinuous burrowing). These influences are directly reflected in the ichnofabric, or biogenic sedimentary fabric.Ichnofabrics of deep-sea sediments can shed light on the ecologic relationships of the infaunal community (trophic and tiering relationships), occupation of the sea floor by successive and different communities (deciphered from the different trace fossil suites in a composite ichnofabric), stability and firmness of the sedimentary substrate (revealed by burrow distinctness and deformation), interstitial oxygen conditions below the sea floor (determined from the abundance and preservation state of deposit-feeding burrows, such as Chondrites and Zoophycos), and effects of bioturbation patterns on early diagenetic processes (differential cementation and mineralization).The sedimentary habitat of the ancient deep-sea floor changes through time via compaction, dewatering, cementation and secondary mineralization. The benthos that inhabit this changing habitat likewise change according to their differing requirements for burrowing and endobenthic feeding. The resulting ichnofabric reflects a successive occupation of the sea floor by different types of organisms, ranging from shallow burrowers to deep burrowers to hard-substrate borers. Composite ichnofabrics thus can reveal a complex sequence of ecologic and diagenetic events.The tiered structure of infaunal communities in late Cretaceous and early Tertiary shelf-sea chalks is well-known, and because of their pelagic depositional aspect, these situations provide good analogues in outcrop for truly deep-sea environments. In the European and North American chalks, deeply emplaced fodinichnia (Thalassinoides, Chondrites and Zoophycos) typically are superimposed upon shallowly emplaced fodinichnia and pascichnia (Planolites and Teichichnus). Tracks and trails of epifaunal animals certainly were produced at the sediment-water interface, but they are not preserved. Very similar ichnofabrics occur in late Cretaceous and early Tertiary pelagic carbonates in New Zealand, where composite ichnofabrics reveal at least five main phases of occupation of the substrate by burrowers and borers. Multiple generations of Thalassinoides include both burrows and borings, each produced at different stages in the development of a major regional unconformity.Deep-sea pelagic deposits (in kilometers of water) represent a continuous accretion of the sea floor during sediment accumulation, accompanied by a continuous vertical shift of a tiered endobenthic community of burrowers that does not change appreciably over short time intervals. In partial contrast, shelf-sea pelagic deposits (in hundreds of meters of water) are affected more directly by short-term changes in bathymetry, salinity and oxygenation. The response of benthic communities to environmental shifts at the sea floor, therefore, is more pronounced in shelf-sea than in deep-sea settings.

scholarly journals Trace fossils from the Lower and Middle Jurassic marginal marine deposits of the Sorthat Formation, Bornholm, Denmark

2003 ◽  
Vol 50 ◽  
pp. 185-208
Author(s):  
Richard G. Bromley
Keyword(s):  
Middle Jurassic ◽  
Trace Fossils ◽  
Trace Fossil ◽  
South Coast ◽  
Marine Environments ◽  
Salinity Fluctuation ◽  
Fossil Assemblage ◽  
Marine Deposits ◽  
Low Degree ◽  
The Baltic

The Lower to Middle Jurassic Sorthat and Bagå Formations of the Baltic island of Bornholm, Denmark, are a predominantly fluviatile unit. On the south coast of the island at Korsodde, however, an interval within the Sorthat Formation contains a diverse trace fossil assemblage indicating a marine incursion. Study of this interval revealed 15 ichnotaxa, among which one is new: Bornichnus tortuosus nov. igen. et isp. Several of the trace fossils present are generally considered characteristic of the lower shoreface to offshore environments (e.g. Teichichnus and Asterosoma). However, the low degree of bioturbation and ichnodiversity, and sedimentological features, indicate an environment influenced by salinity fluctuation, probably a tidally influenced delta. Five ichnofabrics are defined that describe this setting and which may be indicative of marginal-marine environments that are influenced by salinity fluctuations.

An enigmatic trace fossil from the Upper Triassic (Rhaetian) shales of Western Europe

2015 ◽  
Vol 94 (3) ◽  
pp. 271-277
Author(s):  
K.A. Estes-Smargiassi ◽  
A.A. Klompmaker
Keyword(s):  
Great Britain ◽  
Western Europe ◽  
Trace Fossils ◽  
Coastal Environment ◽  
Upper Triassic ◽  
Trace Fossil ◽  
Low Oxygen ◽  
Eds Analysis ◽  
Oxygen Conditions ◽  
Eggs And Larvae

AbstractVarious trace fossils are known from the Upper Triassic (Rhaetian) shale deposits of western Europe, especially from Great Britain. Here we present a unique specimen, unknown from Rhaetian shales in western Europe thus far to our knowledge. The specimen consists of a string of small knobs collected from the dark-coloured Rhaetian shales from the eastern Netherlands, deposited in a marine, near-coastal environment. The specimen represents the first described trace fossil from these shales. The identity of this specimen appears enigmatic. However, SEM-EDS analysis showed that the string of knobs is pyritised and does not contain phosphorus nor did the sediment directly around the specimen, suggesting a non-coprolitic origin of the specimen. Eggs and larvae are also excluded as possibilities. The specimen closely resembles several trace fossils identified as burrows, which is why we favour this interpretation. The rare presence of trace fossils reinforces the hypothesis that the Dutch Rhaetian shales were deposited under a stresses regime with low oxygen conditions.

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