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Giant Paleodictyon in Eocene flysch
Abstract
A giant Paleodictyon gomezi with a maximum mesh diameter of 13 cm and covering more than 0.5 m2 occurs in the lower Eocene flysch near Zumaya. The giant Paleodictyon occurs with flute casts and, therefore, must have been produced deeply in the sediment. The lengthening of mesh cells parallel and perpendicular to the flute casts implies changing current directions during trace production. Rows of elongate and offset mesh cells reflect the row-by-row production of the trace; however, the base line followed by the trace fossil producer (meandering or spiral) cannot be reconstructed because of incomplete preservation. The extraordinary size of this giant Paleodictyon contradicts the evolutionary trend of deep-sea trace fossils toward optimization and miniaturization, since similar large Paleodictyon specimens occur in Silurian flysch.
... Ichnofacies, graphoglyptids are regular, highly patterned predepositional burrows preserved as erosional casts mainly on the soles of turbidites (e.g. Seilacher 1977;Uchman 2003;Seilacher 2007;Monaco 2008;Monaco & Checconi 2010;Checconi & Monaco 2013). They all share the same kind of preservation and normally occur associated to deep-sea turbidites, being characterized by the usual small, submillimeter to millimeter-sized burrows (see Uchman 1995). ...
... However, as it is known from the bibliography, some exceptions to these generalized rules may be found, i.e., taken the most popular Paleodictyon Meneghini, 1850, both for the environmental range where this trace fossil can be found (e.g. Fürsich et al. 2007;Lan & Chen 2010) and for the size of the burrows (Wetzel 2000;Uchman 2003). Protopaleodictyon Książkiewicz, 1970 was recently considered to be an exception in environmental range and size as well (Morgan et al. 2019). ...
... The ichnogenus Protopaleodictyon occurs almost exclusively in flysch deposits (Uchman 1995) as pre-depositional forms, preserved as erosional casts on the soles of turbidites, which is a typical feature of the graphoglyptids (Seilacher 1977;Uchman 1995Uchman , 1998Uchman , 2003Monaco 2008). They are meanders with appendages developed in the background mud rather than hypichnial networks, which lead us to exclude the new ichnospecies P. aitkeni by Morgan et al. (2019) from the ichnogenus Protopaleodictyon. ...
Thalassinoides Ehrenberg, 1944 are relatively common bioturbational structures in carbonate shallow marine successions from the early Paleozoic. Much rarer is the reference to this ichnogenus in siliciclastic formations from the same age. In the Ordovician Lashkerak Formation cropping out at the Central Alborz mountains, Iran, Thalassinoides is a common trace fossil in wave-dominated shoreface complex and prodelta-mouth bar environments of a fluvial-dominated delta. We compare the Middle-to-Upper Ordovician branching networks of the Unit 2 of the Lashkerak Formation with the ichnospecies Thalassinoides horizontalis Myrow, 1995 emphasizing the almost entire bedding-parallel orientation, regular branching and lack of constrictions and swellings. The eodiagenetic halos developed from mucus-lining walls, or by change of the original sediment fabric, typical of this and other ichnospecies of Thalassinoides in carbonate settings are not found in sandstones. The almost polygonal mazes from the Lashkerak Formation are also compared with the recently erected Protopaleodictyon aitkeni Morgan, Henderson & Pratt (2019), considered as a giant graphoglyptid in an early evolutionary stage of these forms in shallow marine environments. Both trace fossils are similar in morphology, size, preservation, ichnofacies and interpreted function, thus being P. aitkeni a junior synonym of Thalassinoides horizontalis.
... The genus Paleodictyon belongs to the group of graphoglyptid trace fossils (Wetzel 2000;Seilacher 2007) common globally in ancient sediments (Kushlin 1982). The earliest records are from shallow-water sediments in the Lower Cambrian but from the early Ordovician onwards; almost all occurrences are from sediments considered to have been deposited in the 'deep sea ' (Buatois et al. 2009). ...
... The size of individual patterns can vary from 25 to 75 mm (Rona et al. 2009;Przeslawski et al. 2012;Durden et al. 2017), and aggregations can cover areas of up to 1 m 2 (Ehrlich 2019). Fossil examples of Paleodictyon are often larger, ranging from 40 to 130 mm (Wetzel 2000), and are typically preserved on the soles of fine-to medium-grained turbidites (Seilacher 1977), while the modern patterns occur on sandy to muddy hemipelagic sediments (Rona et al. 2009;Przeslawski et al. 2012). ...
... There are two main hypotheses regarding the nature of Paleodictyon. These structures are interpreted either as 'trace fossils' formed by the activities of an organism (Wetzel 2000;Seilacher 2007) or as the remains of actual organisms, i.e. 'body fossils' (Rona and Merrill 1978;Rona et al. 2009). According to the trace fossil hypothesis, they reflect the activities of a solitary burrower (Swinbanks 1982;Monaco 2008;Ehrlich 2019), or the Communicated by S. Kaiser * Klaas Gerdes kgerdes@ines-solutions.eu 1 concerted activities of multiple small organisms (Honeycutt and Plotnick 2005;Fan et al. 2018). ...
Compared to the widespread occurrence of Paleodictyon in the geological record, in situ observations of this trace (herein termed ‘pattern’) in modern deep-sea sediments are still scarce, being confined to the Mid Atlantic Ridge, the South Atlantic, southwestern Pacific and the eastern equatorial Pacific Clarion-Clipperton Zone. Here, we report the discovery of Paleodictyon along the southern Central Indian Ridge and the Southeast Indian Ridge within the German license area for the exploration of marine massive sulfide deposits in the Indian Ocean. The patterns occur in sedimented areas, especially those closer to hydrothermal vents and sometimes in aggregation of up to forty, resulting in maximum densities of 9.7 patterns m−2. While many show the grid-like array of holes on the sediment surface that is typical of the modern examples of the genus, the pattern sometimes loses its regularity, in particular on thin veneers of patchy sediment overlying hard basalt substrate, a mode of occurrence reported here for the first time. Other examples appear to be in various stages of natural erosion, in some cases creating unusual linear features.
... The origin of net-like fossil Paleodictyon traces has proved difficult to explain (Seilacher 2007), while the organism responsible for the modern Paleodictyon nodosum structure has eluded discovery, despite detailed in situ submersible observations and intensive analysis of collected material (Rona et al. 2009). It has been suggested that they represent a biogenic sedimentary structure, such as a burrow (Wetzel 2000), or microbial farms for which the vertical shafts provide ventilation (Seilacher 2007;Monaco 2008). Other ideas are that the structure itself is an organism, such as a sponge (Ehrlich 2010) or a xenophyophore (Swinbanks 1982;Levin 1994). ...
... The overall shape is hexagonal to round, with internal hexagons defined by the holes (Ehrlich 2010). Possible burrow formation mechanisms are detailed by (Wetzel 2000), but a burrowinganimalwouldtravel huge distancesrelativetoits body length to construct such a burrow (Rona et al. 2009). The symmetry and proportional size increase have been interpreted as indicative of an organism (Rona and Merrill 1978), rather than a burrow. ...
... The symmetry and proportional size increase have been interpreted as indicative of an organism (Rona and Merrill 1978), rather than a burrow. Somemorphologicalvariationshavebeenobserved;elongationof the pattern (Wetzel 2000) is considered to be tracemaker-controlled, while three-dimensional deformation is thought to be related to the burrowing action (Monaco 2008). Rona et al. (2009) observed some specimens to be flat, while others formed a relief above the sediment surface with a lip around the form; the former was interpreted as degraded and the latter as fresh. ...
Paleodictyon is an important trace fossilcharacterised by a regular hexagonal structure and typical of ancient deep-ocean habitats as far back as the Ordovician. It is represented in modern deep-sea settings by Paleod ictyonnod osum , known from the Mid-Atlantic Ridge, the SouthAtlantic, and off eastern Australia. Here we report the occurrence of P. nodosum in the Clarion Clipperton Zone (CCZ), abyssal equatorial Pacific, an area characterised bypolymetallic nodule fields. At the study site within the International Seabed Authority northeastern Area of Particular Environmental Interest (APEI-6), P. nodosum appeared as a compact, regular pattern of small circular openings on the seafloor, each pattern interpreted as reflecting the activity of an individual organism. The patterns had a mean size (maximum dimension) of 45 mm ± 16 mm SD (n = 841) andoccurred at a density of 0.33 individuals m−2. Most (82%) were interrupted by nodules, but those that were not displayed both regular (59%) and irregular (41%) forms, the former having equal numbers of rows along the three axes (6 x 6 x6 and 8 x 8 x 8). In both size and morphology, our Paleodictyon traces were more similar to the Australian examples than to those from the Mid-Atlantic Ridge.
Link:
http://link.springer.com/article/10.1007/s12526-017-0636-0
... Furthermore, although the trace displays distinctive partial hexagonal geometries, no complete hexagonal mesh has been constructed, meaning the trace is not a true network (sensu Uchman, 1998). The lack of an interconnecting, complete hexagonal mesh precludes diagnosis of this trace as Paleodictyon (see Uchman, 1995Uchman, , 1998Wetzel, 2000 for diagnostic/taxonomic information relating to Paleodictyon). Ophiomorpha irregulaire and O. nodosa are commonly noted to construct regular polygonal, three-dimensional burrow maze networks (Frey et al., 1978) that superficially may resemble large Paleodictyon networks. ...
... Comparison with Similar Forms. -Wetzel (2000) reported a giant Paleodictyon from the Zumaia section that resembles the specimens reported here. Wetzel's giant Paleodictyon has a maximum string diameter of 6.5 mm with mesh diameter averaging 85 mm. ...
... Using Uchman's (1995) criteria this specimen was diagnosed as Paleodictyon gomezi. The key difference between the Zumaia specimen and those reported herein is the predepositional nature (Wetzel, 2000) compared with the postdepositional nature of the specimens reported here. Wetzel's specimen is a true network with the hexagonal mesh interlocking (albeit in an eroded state due to the predepositional nature of the trace). ...
Ophiomorpha group trace fossils occur abundantly in a range of Eocene-aged deep-marine environments of deposition in the Basque basin, northern Spain. The morphology and dimensions of these trace fossils, observed in off-axis submarine lobe deposits, are discussed. The reported specimens display a highly organized and systematic burrowing behavior preserved on turbidite bed bases that display interconnecting Y-shaped (hexagonal-polygonal) morphologies. This observation, together with the cross-cutting relationship with tool marks, suggests construction of postdepositional agrichnial burrow networks. The networks probably harvested microbes that broke down cellulose-based organic matter providing an exploitable nutrient source for crustacean trace makers of Ophiomorpha. Therefore, the Ophiomorpha group related traces discussed herein are postulated to represent an ethological response to changes in deep marine environmental conditions driven by global climate change during the early Paleogene, including the early Eocene hyperthermal events.
... Remarks. The specimens correspond well with the description of P. gomezi of Wetzel (2000), Uchman (1998) and Crimes & McCall (1995) and, in addition, are very similar to the specimens described by Crimes (1977;e.g. his pl. ...
... 4c, e, p. 85). According to Wetzel (2000) the penetration depth of this very large type of Paleodictyon is distinctly deeper than the normal shallow burrowing depth of Paleodictyon, suggesting a positive correlation between the size and the penetration depth of this ichnogenus. This trend corresponds well with the present samples, since P. gomezi represents the highest relief in comparison with other traces on the same slab. ...
The Vera Basin is one of a series of interconnected Neogene–Quaternary-age basins located within the Betic Cordillera in SE Spain. The initial marine phase in the basin is represented by the sedimentary succession of the Abad Member (Tortonian–Messinian) and comprises mainly marls with varying amounts of intercalated siliciclastic–calcareous turbidites. The succession contains a rich ichnofauna comprising 12 ichnogenera (21 ichnospecies), which can be subdivided into a number of distinct ichnoassemblages. Detailed analysis of the distribution of these ichnoassemblages reveals that deposition occurred within the Nereites ichnofacies, more specifically, the Paleodictyon sub-ichnofacies, presumably in a lobe-type setting, and at epi- to mesobathyal depths (i.e. 200–1000 m). Changes within the ichnofacies suggest that there is a clear deep-through-to-shallow trend within the succession extending from the older (i.e. Almocáizar Corridor) to the younger (i.e. centre of the Vera Basin) parts of the succession. These changes coincide with the onset of the Messinian Salinity Crisis (MSC) across the region, and correlate well with the pre-MSC through to Lago Mare deposits.
... Fig. 6 illustrates ¢ve iterations of this rule. The pattern produced is very similar to that of the enigmatic trace fossil Paleodictyon (Seilacher, 1977;Garlick and Miller, 1993;Levin, 1994;Wetzel, 2000). I have observed similar 'dangling ends'; i.e. the unattached ends, in specimens of this fossil from the Eocene of the Carpathians. ...
... Crimes and Fedonkin (1994), in contrast, found no evidence of an optimization during the Phanerozoic in trace fossil morphology, with the possible exception of spiral traces. More recently, Wetzel (2000), based on the assumption that Paleodictyon represents a burrowing trace, used the existence of an extremely large Eocene form of this ichnogenus to argue against optimization. ...
Trace fossils represent the preserved interactions of trace making organisms with their environment. The form of traces should result from complex interactions among the organism’s morphology, the behavior being carried out, the organism’s perception of the environment, and the heterogeneity of the environment. Existing mathematical models for the biological formation of traces have tended to focus on a limited repertoire of behaviors, such as grazing. They do not include realistic patterns of environmental heterogeneity, differences in perception, or multiple behavioral responses. In addition, there have been almost no attempts to model 3-D traces, or traces that branch or anastomose. New models for grazing and crawling traces can be built on current research by ecologists into animal movement patterns and their interaction with environmental heterogeneity. These models explore the interactions of alternative spatial patterns of environmental heterogeneity with different perceptions and behavioral responses to it. They have the potential for suggesting how behavioral patterns for a given trace making organism might change as a function of environmental differences, such as resource distribution. This could be a useful tool for determining such patterns of spatial heterogeneity in ancient environments. A second approach can be based on recent developments in the computer-based study of morphogenesis. This technique utilizes L-systems and related methods for the generation of branching and 3-D theoretical morphologies. L-system descriptions can be quite complex and can incorporate realistic concepts of growth, including external environmental factors and signal transmission. They have been used previously for the production of simulated plants of startling realism. By altering the parameters used to generate the simulated fossils, a theoretical morphospace for trace morphology could be constructed.
... Despite that, starting in the Precambrian, their diversity has increased above shallow-marine ichnocoenoses by late Cretaceous-Early Tertiary time. The general idea is that such burrows normally occur on distal turbidites soles, in flysch (Seilacher, 1962(Seilacher, , 1977aCrimes & Fedonkin, 1994;Bromley, 1996;Seilacher & Gishlick, 2014), but they are found in other environments, such as non-marine deposits (Archer & Maples, 1984;Pickerill, 1990), neritic (Hantzpergue & Branger, 1992;Stanley & Pickerill, 1993) or lithographic limestones of offshore (Wetzel, 2000). In Romanian literature, eight ichnospecies (Paleodictyon isp., P. tellini, P. regulare, P. minimum, P. majus, P. carpathicum, P. miocenicum, P. gomezi) from different formations (Paleozoic, Mesozoic, and Tertiary in age) were described, most of them from Outer East Carpathians (Joja, 1955;Alexandrescu & Brustur, 1980;Alexandrescu & Brustur, 1990;Brustur, 1995). ...
Hypichnia with Strobilorharphe, Megagrapton, Spirodesmos, Helminthopsis, Treptichnus, and the elite Paleodictyon, representative for "deep-sea farmers" (graphoglyptides) of the Paleodictyon ichnosubfacies, belonging to Nereites ichnofacies is described in Lower-Middle Eocene flysch deposits of Tarcău Nappe (in the north of Eastern Carpathians). The Paleodictyon is preserved as three superimposed networks, covering a half square meter of lower bounding surface of a Tc bed, indicating a quasi-nonerosive character of the turbidity current which exhumed the pre-depositional delicate farming traces. This paleoenvironment is supported by the agglutinated foraminifera, dominated by tubular forms (Bathysiphon sp., Psammosiphonella cylindrica, Nothia excelsa) collected from shale the above and below turbidite bed, accumulated in relative quiet intervals, depleted of nutrients and oxygen. Such conditions may exist in offshore, where organisms develop highly organized feeding strategies.
... Remarks: Paleodictyon Meneghini (1850) is a distinct trace fossil preserved commonly as casts on the sole of fineto medium-grained turbidites (Peruzzi 1880). Paleodictyon belongs to the group of trace fossils known as graphoglyptids, which includes a large number of ichnotaxa and are highly organized trace fossils normally found as casts on the lower surface of distal turbidites (Wetzel 2000;Seilacher 2007). Trace-makers of Paleodictyon are inferred to be farming microbes and are, therefore, included in the ethologic group of agrichnia. ...
The presence of trace fossils and their diversity in Miocene deposits of western Makran accretionary prism (SE Iran) was the center of this research. The trace fossil contents of Cheraghsuz and Sardasht (with Middle Miocene in age) and Gowharan (with Early Miocene in age) stratigraphic sections were analyzed. The recognized specimens of the Cheraghsuz section are Gordia isp., Helminthopsis hieroglyphica, Helminthopsis abeli, Helminthorhaphe flexsuosa, Paleodictyon maximum, and Spirorhaphe involuta. The Sardasht section is composed of Gordia isp., Helminthopsis hieroglyphica, Helminthopsis
abeli, Helminthorhaphe flexsuosa, Paleodictyon maximum, Paleodictyon majus, Paleodictyon isp., Spirorhaphe involuta, Helicolithus isp., Helicorhaphe tortilis, and Neonereites isp.. In the Gowharan section, some gastropod trails, a giant and very well-preserved Archaeonassa-like ichnogenus, and ripple marks were observed. Majority of the recognized trace fossils are of the graphoglyptid group. The trace fossil contents of Cheraghsuz and Sardasht sections are compatible with Nereites ichnofacies; as graphoglyptids are thought to be indicative of oligotrophic conditions, the trace-producers are filter-feeder organisms that normally tend to take suspended nutrient materials in the water column, but due to lower sedimentation rate, the nutrient content is concentrated on the superficial part of the substrate; accordingly, the trace-makers prefer grazing and
moving on the surface sediment to take their food. However, the exceptionally preserved trace fossils in Gowharan section should be formed in a tidal flat environment. In relation to the floor, it has recorded at least three shapes, including bi-lobed, uni-lobed and submerged forms. In addition, it could be observed that different trace fossils may be created by a single animal and different animals may create the same trace fossils.
... The origin of the living fossil pattern traces has been widely discussed, with two main theories put forward as to what they represent: (1) Paleodictyon forms are trace fossils and the hexagonal network a burrow structure (Garlick and Miller 1993;Wetzel 2000), or traces of microbial 'farms' (Seilacher 2007); alternatively (2) Paleodictyon forms are actually body forms of an organism such as a xenophyophore (Swinbanks 1982;Levin 1994;Rona et al. 2009) or of a compressed hexactinellid sponge (Rona and Merrill 1978;Ehrlich 2019). How the hexagonal network is formed also remains uncertain. ...
Since the late 1980s, various experiments have been conducted in polymetallic nodule fields of the Pacific Ocean to assess the potential environmental impacts of future mining, specifically in two areas: the Peru Basin and the Clarion-Clipperton Fracture Zone (CCZ). Two expeditions, SO242/2 in 2015 (Peru Basin) and SO268/1 + 2 in 2019 (CCZ), deployed a towed camera system to collect imagery from both areas. These expeditions aimed to assess recovery of fauna in the short (few weeks) and long term (several years) following physical seafloor disturbance actions designed to mimic potential mining, by ploughs, dredges and epibenthic sleds. Within the collected image data, several strikingly hexagonal hole patterns were observed and identified as Paleodictyon nodosum , and an irregular form of Paleodictyon traces, both on undisturbed and disturbed areas of seafloor. Recent forms occur abundantly in various deep-sea regions, but their origin, and how they represent the mode of life of the forming organism, remains unknown. In this study, the imaged occurrences of Paleodictyon traces on disturbed seafloor sheds light on the lifecycle of the forming organism, demonstrating that they can recolonize disturbed habitat and produce the trace network in a few weeks. Nevertheless, the density of these patterns on disturbed substrates was lower than observed on undisturbed substrates in both nodule regions. We therefore hypothesize that, along with other benthic deep-sea fauna, these structures and the forming organism are impacted by physical seafloor disturbance, and even 26 years after disturbance, densities on disturbed sediments have not recovered to undisturbed levels.
... spinata caused by increasing erosional overprinting (Paleodictyon isp. redrafted from Wetzel, 2000; Pr. spinata redrafted from Uchman, 1998). ... 215 Figure 6.1 Diagrammatic cross-section and T-R sequence stratigraphic model for the Wuliuan Stage (regional Delamaran-Topazan stages, middle Cambrian) succession of western Canada (redrafted and modified from with additional information from Pugh, 1971;Stewart et al., 1993;Slind et al., 1994 and sedimentologic examination of the Stephen Formation has been completed following the method and principles of microfacies analysis (Chapter 2) to interpret the depositional conditions and sequence stratigraphic processes which created the unit ~half a billion years ago (Coppold and Powell 2000). ...
Carbonate microfacies and trilobite successions were examined in seven sections of the Stephen Formation, southern Canadian Rocky Mountains. Seven microfacies and three ichnofacies are identified, including a new Protopaleodictyon ichnofacies with Protopaleodictyon aitkeni (n. isp.). Palaeoenvironments include ephemeral oolitic shoals, intraclastic/oncoidal tempestites, and quiescent muddy-bottomed mid-shelf within a low-latitude, carbonate platform. Three parasequences were identified in the Narao Member, and five in the Waputik Member. Narao Member parasequences are sub-tidal muddy carbonate, shallowing toward microbial build-ups. Waputik Member parasequences contain green-grey, laminated shale, with sporadic carbonate tempestites, indicating a platform inundated by upwelling cool-dysoxic water. Carbonate production was shut-off, except within localized shoals and build-ups. The stacking pattern indicates slow base-level change with periodic upwelling events. The overlying Eldon Formation re-established carbonate platform deposition associated with a stabilised chemocline. Chemocline perturbation is postulated to affect trilobite biomere extinction at the Narao-Waputik boundary. Fifteen trilobite species, eleven trilobite genera, one orthothecid, one edrioasteroid, and three Burgess Shale organisms (Tuzoia, Haplophrentis carinatus, Margaretia dorus) were identified in the Stephen Formation, which ranges from the uppermost Glossopleura Assemblage Biozone into the Ehmaniella Assemblage Biozone. Four new biozones are established in this interval, including the Glossopleura boccar, Proehmaniella basilica, Ehmaniella waptaensis, and Spencella montanensis interval biozones. A quantitative biostratigraphy using Unitary Association (UA), integrates regional biozones from southwestern USA and western Canada into a unified Miaolingian trilobite succession (582 taxa, 1035 samples, 121 sections, and 48 formations). Seventy-three UA biozones, including 33 previously defined biozones, are delineated from the upper Bonnia-Olenellus to Cedaria assemblage zones. Six new Wuliuan interval biozones (Fieldaspis superba, Albertella bosworthi, Glossopleura boccar, Proehmaniella basilica, Spencella montanensis, and Bathyuriscus adaeus) are established. Nineteen UA zones encompass the top of the upper Bonnia-Olenellus Assemblage Biozone, 11 in the Plagiura-Poliella Assemblage Biozone, 18 in the Albertella Assemblage Biozone, 10 within the Glossopleura Assemblage Biozone, 7 within the Ehmaniella Assemblage Biozone, and 8 in the Bolaspidella and Cedaria biozones. This is the first recognition of temporal equivalence of regional biozones using quantitative biostratigraphic methods. The faunal succession informs biostratigraphic correlation potential pointing to mid-Cambrian intervals that may yield additional high-resolution biozones in the future.
... During the last years, ichnological information has been included as a criterion to differentiate between different types of deep-water deposits such as pelagites/hemipelagites, turbidites, contourites, and hyperpycnites, yet with a variable coverage. Thus, as pelagic/hemipelagic and turbiditic sediments have been profusely studied and ichnologically well-defined (e.g., Wetzel, 2000;Uchman, 2007;Wetzel, 2011, 2012;Wetzel and Uchman, 2012;, contourites are now in the first phases of characterization, showing significant results (e.g., Wetzel et al., 2008;Alonso et al., 2016;Rodríguez-Tovar and Hernández-Molina, 2018;Dorador et al., 2019;Rodríguez-Tovar, 2019b, 2020;Rodríguez-Tovar et al., 2019a. The ichnological characterization of hyperpycnites is also still in the first steps, with only a few studies in which trace fossils have been emphasized, showing the variability of environmental context and the absence of a unique ichnological pattern (see Buatois et al., 2019). ...
Hyperpycnal flows have been widely described in different lacustrine and marine environments but sedimentary structures and fossil content in hyperpycnites often offer limited information about the palaeoenvironmental conditions. This limitation can be improved by ichnological analysis, which has been recently used as a tool to differentiate between different type of subaqueous deposits, even though still only a few detailed ichnological studies on hyperpycnites exist. In order to bridge this gap in knowledge, a 50 m-thick package of terrestrial organic debris-rich, dominantly structureless and well-sorted sandstone bodies alternating with burrowed siltstones (Upper Miocene, Betic Cordillera, Spain) is here analyzed. This study is based on observations of a well-exposed outcrop and cores from a well drilled just behind the outcrop to bridge field-scale observational gaps. Two type of sandbodies were typified on the basis of their stratigraphic architecture, physical sedimentary structures, and ichnofacies in the fine-grained deposits embedding them: (1) Lobate to channelized-top sandstones embebbed into silty sands with dominant highly variable degree of bioturbation by Taenidium and Schaubcylindrichnus (depauperate Cruziana ichnofacies) and interpreted as proximal marine sustained hyperpycnites in prodelta settings; and (2) channelized-lobate (cut-and-fill sequence) sandstones embebbed into siltstones with dominant Nereites and Phycosiphon (Nereites ichnofacies) interpreted as distal hyperpycnites developed in offshore settings. The studied succession is interpreted to represent the progradation of a sandy hyperpycnal system along a prodelta to starved offshore setting with high variability in grain-size, benthic food and oxygen content. Results of this study suggest that a multi-scale analysis focused on trace fossils and physical sedimentary signatures is needed to get a better understanding of these river-derived sustained-flow turbidites (hyperpycnites) that are less well known than their conventional surge-type turbidite counterparts.
... spinata caused by increasing erosional overprinting (Paleodictyon isp. redrafted fromWetzel, 2000; Pr. spinata redrafted fromUchman, 1998). ...
A new and large ichnospecies of Paleodictyon Meneghini, 1850, was discovered in the Ehmaniella biozone of the Stephen Formation at Helena Ridge, Banff National Park. This new ichnospecies is preserved in hyporelief on the sole of a thick dolomitic mudstone talus block near the mid-Cambrian Stephen-Eldon Formation boundary. The trace is formed of linear mesh structures in an overall radiating net. The dimensions of this trace are exceptionally large with mesh diameters of 25-40 mm and string diameters of 5-10 mm. The trace fossil is compared to Treptichnus, Squamodictyon, and Protopaleodictyon, but these ichnogenera are rejected because of the angularity of stringer branching and the overall radiating nature of the trace. This new ichnopecies has the largest sting diameter recorded for Paleodictyon based on morphometric analyses produced by Uchman (2003). The trace was formed in a mid-inner carbonate platform paleoenvironment. This new occurrence helps to address previous interpretations that Paleodictyon and other graphoglyptids originated in shallow marine environments during the Early Paleozoic before migrating to deeper facies after the Ordovician (Crimes, 2001). What remains unusual is the lithology in which this trace was located. This may represent one of the first recorded occurrences of Paleodictyon in non-siliciclastic material.
References
Crimes, T.P. 2001. Evolution of the deep-water benthic community. In A.Y Zhuravlev., and R. Riding (eds.), The Ecology of the Cambrian Radiation. Columbia University Press, New York, 525 p.
Salvi, P., & Meneghini, G.G. 1850. Osservazioni stratigrafiche e paleontologiche concernenti la geologia della Toscana e dei paesi limitrofi. In R. Murchison (ed.), Memoria sulla struttura geologica delle Alpi degli Apennini e dei Carpazi, Stamperia granducale, Florence, 246-528.
Uchman, A. 2003. Trends in diversity, frequency and complexity of graphoglyptid trace fossils: evolutionary and palaeoenvironmental aspects. Palaeogeography, Palaeoclimatology, Palaeoecology, 192, 123-142.
... spinata caused by increasing erosional overprinting (Paleodictyon isp. redrafted fromWetzel, 2000; Pr. spinata redrafted fromUchman, 1998). ...
A new ichnospecies of Protopaleodictyon Książkiewicz, 1958 Książkiewicz, M. 1958. Stratigraphy of the Magura Series in the Średni Beskid (carpathians.). Biuletyn Instytutu Geologicznego 153:43–96. [In Polish, with English summary] [Google Scholar], Pr. aitkeni isp. n., is named from material recovered from the mid–Cambrian Stephen–Eldon formation transition in Banff National Park, Alberta, Canada. Specimens occur in convex hyporelief on the sole of a dolomitic lime mudstone bed, and exhibit straight to gently curving strands with a 'zigzag' shape up to 45 cm in length. Strands are fairly regular, with branching angles ranging from 110° to 120°. Branch segments forming the strand are approximately the same length and produce strands with open and occasionally closed hexagonal polygons arranged alternatively along the specimen's axis. Hexagons are 25–40 mm wide and string widths are 5–10 mm. The dimensions of Pr. aitkeni are large compared to other ichnospecies of the ichnogenus and graphoglyptids in general. The host interval is interpreted to have been deposited in a relatively shallow-water environment in the interior of a carbonate platform, contrasting with the deeper siliciclastic settings in which younger examples of the ichnogenus typically occur. This occurrence further supports the hypothesis that graphoglyptid ethology initially developed in shallow shelf environments before shifting into deeper facies over geologic time.
... For example, tunnel width and burrow system width of Chondrites aid separation of C. stellaris Uchman and C. affinis (Sternberg) (Uchman, 1999; from the four Chondrites ichnospecies recognised by Fu (1991). Mesh size and tunnel diameter also help differentiate the numerous Paleodictyon ichnospecies Golev, 1965, 1966;Książkiewicz, 1977;Uchman, 1995;Wetzel, 2000). These size measures of a certain ichnogenus probably reflect both intraspecific (including ontogenetic) and interspecific variations of the trace makers. ...
The ichnogenus Helminthorhaphe is a meandering trace fossil valuable to the study of movement behaviours of the trace-making marine invertebrates. In this work, we studied systematically the morphology of selected examples of Helminthorhaphe from the Upper Cretaceous to Miocene by means of primary morphological constructs, morphometrics, and theoretical morphological models. Eleven morphological constructs encompassing meander arrangement, meander tip, and meander course properties are established to illustrate the essential morphological features of meanders, which cover key aspects of the motion and navigation capacities of Helminthorhaphe makers. Tunnel diameter, meander width, and meander length are extracted to explore the size range of Helminthorhaphe, from which an exceptionally large end member is recognised, H. magna ichnosp. nov. Meander width versus tunnel diameter ratio and the fractal dimension of Helminthorhaphe are two prominent morphometric parameters that characterise the average closeness and space usage of the meanders, respectively, which aid differentiation between ichnospecies. Helminthorhaphe miocenica, H. magna, H. flexuosa, and H. japonica generally conform to a series of increasing closeness and space usage of the meanders. Theoretical morphogenetic analysis of the meander-generating process of Helminthorhaphe based on the bilateral phobo-thigmotactic robot car model reveals that the tempo and hierarchy of bilateral movement differentiation contribute to the formation of primary terminal U-turn at the meander tip, as well as lower-level meander-course undulations. The meander tip property proves to be an important morphological feature with biomechanical and neurobiological implications on the body flexibility and lateralisation in the nervous system of Helminthorhaphe producers. Larger-scale meander arrangement styles suggest that Helminthorhaphe makers potentially possessed certain radial or concentric spatial cognition of the environment. With an emphasis on theoretical morphogenetic analysis, this study provides a preliminary attempt in linking ichnology with behavioural, neurobiological, and intelligence sciences.
... The agrichnial assemblage in the Vera Basin is one of only a few examples of very young (6 to 7 million years old) graphoglyptid trace fossils, and thus it serves to link the well-known Cretaceous-Palaeogene record of such fascinating trace fossils (Seilacher, 1974(Seilacher, , 1977(Seilacher, , 2007Wetzel, 1983Wetzel, , 2000Uchman, 2003) with their elusive modern representatives observed in deep-sea bottom photos (Rona et al., 2009) and recovered in deep-sea cores (Ekdale, 1980). Figure 6. ...
The Vera Basin in southeastern Spain was a small, tectonically active depocenter throughout the Miocene. In the early Messinian, approximately 7.2 to 6.0 million years ago, the basin received hemipelagic marl deposits that were punctuated by turbidite events. Soles of thin, turbidite sand beds preserve an abundance of pre-depositional graphoglyptid (agrichnial) burrows that represent diverse deep-sea ichnocoenoses, including Paleodictyon, Urohelminthoida and Helminthorhaphe. Post-depositional feeding burrows, including Ophiomorpha (created by crustaceans) and Scolicia (created by echinoids) occur sparsely in some turbidite beds, but they are far out-numbered by the predepositional agrichnial burrows. This diverse trace fossil association occurred in a small, short-lived, coastal basin that apparently never got more than a few hundred meters deep. As the basin opened up and flooded in the Late Miocene, the sea floor was colonized rapidly by benthic organisms of uncertain biological affinity, who created a wide variety of anastomosing and meandering tunnels, in which a nourishing food supply (probably bacteria or fungi) apparently grew on mucus-lined walls.
... trace fossils from the Guipúzcoan Flysch of the Higuer-Getaria Formation (lower Eocene) from Zumaia, Spain, were studied. The turbidite sequences containing the graphoglyptids are well-exposed and celebrated for their high abundance and diversity of deep marine trace fossils (Seilacher, 1977;Wetzel, 2000). The depositional environment for these turbidite sequences includes the basin plain, outer fan, and depositional lobes of the middle fan (Leszczyński, 1991). ...
The analysis of trace fossils usually is performed qualitatively, which makes comparing trace fossils from different units less objective than quantitative approaches. Quantifying the shape of trace fossils enables scientists to compare trace fossils described by different people with greater precision and accuracy. This paper describes several methods for quantifying invertebrate trace fossils, including morphology dependent methods (motility index, mesh size, topology, tortuosity, branching angle, and the number of cell sides) and morphology independent methods (fractal analysis, burrow area shape, and occupied space percentage (OSP)). These tools were performed on a select group of graphoglyptid trace fossils, highlighting the benefits and flaws of each analytical approach. Combined together, these methods allow for more objective comparisons between different trace fossils.
... The most instructive way to determine what ethologic strategies might have been used by graphoglyptid producers would be to compare real graphoglyptid For this study, a number of graphoglyptid examples from the Guipúzcoan Flysch of the Higuer-Getaria Formation (lower Eocene), Zumaia, Spain were examined (Fig. 9). Well-exposed sections of graphoglyptid-rich turbidite sequences in this region are celebrated for their high abundance and diversity of deep-marine trace fossils (Seilacher, 1977;Wetzel, 2000). The turbidite facies represented include basin plain, outer fan, and depositional lobes of the middle fan (Leszczyński, 1991), where each turbidite layer was deposited once every few thousand years (Gawenda et al., 1999). ...
Graphoglyptids are a group of deep-sea trace fossils that exhibit ornate burrow geometries. Feeding patterns represented by these burrows have been interpreted as fodinichnial (mining), pascichnial (grazing), and/or agrichnial (farming). In this study, several different graphoglyptid trace fossils were analyzed quantitatively using fractal analysis to determine which of these three feeding modes is most appropriate as an interpretation. Graphoglyptid burrows lend themselves to fractal geometric analysis, because they commonly exhibit the essential fractal characteristics of scale invariance and self similarity. Fractal analysis is presented as a tool for analyzing geometric configurations by combining shape complexity and space usage into one number, the fractal dimension. Fractal dimensions of such graphoglyptid burrows as Paleodictyon and Spirorhaphe were compared with those of known fodinichnial burrows, such as Zoophycos, and pascichnial trails, such as Scolicia, all from Zumaia, Spain. Results indicate that the deposit-feeding burrows (fodinichnia and pascichnia) illustrate a high fractal dimension, as would be expected for a deposit-feeding–optimal foraging strategy. Graphoglyptids illustrate a consistently lower fractal dimension than the deposit-feeding burrows, thus providing evidence against the suggestion that they represent fodinichnial or pascichnial behaviors. This observation supports the hypothesis that graphoglyptids represent agrichnial activity rather than mining or grazing activities.
... The mesh sizes of Cambrian Paleodictyon range from about 10 mm in material from Poland to 80 mm in material from Nova Scotia. The latter are within the range of later large Paleodictyon, which may reach 13 cm, and there are several Palaeozoic and Palaeogene occurrences with mesh diametres in the range of 5-7 cm (see Wetzel 2000). What on the data available is missing in the Cambrian is especially small (meshes smaller than 10 mm) Paleodictyon. ...
We examined the palaeogeographical distribution of selected Cambrian trace fossils. Astropolichnus hispanicus, Climactichnites, Syringomorpha nilssoni and early examples of Paleodictyon all have a restricted palaeogeographical distribution, probably representing that of their producers. A cosmopolitan distribution is seen in Didymaulichnus miettensis and in early examples of Rusophycus and Dactyloidites. Oldhamia shows a wide distribution in Lower Cambrian deep-sea sediments although that of Oldhamia geniculata is restricted.
... Paleodictyon Meneghini in Murchison (1850) is morphologically distinct from other ichnogenera and widely recognised in the fossil record as well as modern oceans (Fü rsich et al. 2007). It is also among the most characteristic ichnotaxa of the Nereites ichnofacies, a distinct assemblage indicating bathyal to abyssal environments (Seilacher 1967(Seilacher , 1977aCrimes 1977;Frey & Pemberton 1984;Bromley 1996;Wetzel 2000;Uchman & Tchoumatchenco 2003;Uchman et al. 2004;Uchman 2007;Wetzel et al. 2007). Similar traces are also seen in modern deep seas (Rona & Merrill 1978;Ekdale 1980;Ekdale et al. 1984;Gaillard 1991;Miller 1991;Rona 2004;Rona et al. 2009). ...
Additional material of Paleodictyon from the Guadalupian (Middle Permian) Mungadan Sandstone (Kennedy Group) of the Carnarvon Basin, Western Australia, is documented here. The Mungadan Sandstone was deposited in a nearshore depositional setting as evidenced by the lithofacies, ichnofacies and fossil assemblage. The Carnarvon Basin specimens agree well with the morphology of Paleodictyon. SEM images of a mesh string/burrow show abundant framboids, which are interpreted as the result of decomposition of organic remains of the tracemakers. The Carnarvon Basin specimens provide an additional example that tracemakers of Paleodictyon live in much broader range of habitats than commonly assumed, ranging from deep sea to shoreface/nearshore settings. Broad spatiotemporal distributions suggest that Paleodictyon traces could have been made by different organisms with similar behaviours during the Phanerozoic.
... Even opposite examples can be invoked. In the Eocene, for example, some giant forms do occur, such as Paleodictyon gomezi (Wetzel, 2000), Glockerichnus alata (Seilacher, 1977b;Tunis and Uchman, 1998), Dendrorhaphe haentzscheli (Seilacher, 1977a;Uchman, 1999), and Estrellichnus jacaensis . ...
Graphoglyptids, a characteristic component of the Nereites ichnofacies, are patterned, mainly meander-, star-, and net-shaped trace fossils, which reveal complex burrow systems used most likely for trapping of meiobenthos or cultivation of microbes in oligotrophic deep-sea environments. They show considerable changes of diversity, frequency and adaptive radiation through Phanerozoic. Rapid radiation and increase of their diversity and density in the Late Cretaceous, probably in the Turonian, is correlated with large-scale biotic changes in marine environments, which are rooted in palaeogeographic and palaeoclimatic changes. The changes of graphoglyptids have been distinctly caused by most of the major biotic crises, especially in the Cretaceous and Cenozoic. Graphoglyptids also display an increase of complexity, which accelerated in the Late Cretaceous, when the farming activity of their trace makers became more common. The distinct changes in development of graphoglyptids challenge the time-stability hypothesis for explanation of their evolution.
Autor w pracy przedstawia „meandrującą skamieniałość śladową” pochodzącą z terenu Karpat Zewnętrznych. Badany okaz pochodzi z utworów oligocenu (warstwy krośnieńskie) odsłaniających w Roztokach Dolnych koło Baligrodu (Bieszczady Zachodnie). Ślady tego typu tworzą zygzakowate wzory,. Pod względem etologicznym struktury te zaliczane są do pasichnia, fodinichnia. Wielkość całego okazu szacowana jest na 8 cm długość, natomiast poszczególne odcinki skamieniałości śladowej mają 4 cm, szerokość nory 5 mm. Prezentowana skamieniałość klasyfikowana jest do rodzajów Protopaleodictyon .Badany okaz podobny jest do ichnoskamieniałości opisywanych z margli fukoidowych należących do warstw inoceramowych (górna kreda). Przedstawiony okaz morfologicznie zbliżony jest do gigantycznych form opisywanych z Kanady (kambr) oraz Hiszpanii (eocen), zaliczanych do ichnorodzaju Protopaleodictyon. Jak dotąd wielkość opisywanych „meandrujących skamieniałości śladowych” z fliszu karpackiego nie przekraczała 3 cm.
This study examined the functional morphology of the trace fossil Paleodictyon in terms of computational fluid dynamics. The modern specimens show a unique morphology that is composed of a hexagonal mesh structure, vertical shafts opening to the seafloor, and a shield-like mound on the seafloor. The traces of the vertical shafts were also preserved in some fossil examples. To explain their characteristic morphology, a passive ventilation hypothesis has been proposed suggesting that their function was to ventilate their burrows with bottom currents, which supply both oxygenated water and food. However, this hypothesis has not yet been verified. This study conducted numerical experiments to understand the functions of the structures created by this ichnofossil by using a model of computational fluid dynamics with the 3D geometry of Paleodictyon and estimating the efficiency of the ventilation in burrows. As a result, it was observed that seawater flowed in the vertical shafts in the marginal area of the mound, and flowed out from the shafts located on the top of the mound, flowing through the mesh structure. This ventilation was observed only in the case that Paleodictyon had a shield-like mound. The ventilation rate rapidly increased as the bottom current velocity increased. In contrast, the rate also increased with the height of the shield-like mounds, whereas it once dropped after the minor peak at 4 mm in height, which corresponds to the value measured in the modern specimens. This coincidence may imply that the height of the mound observed in modern specimens resulted from the optimization in balancing between the efficiency of ventilation and physical stability against erosion. Full exchange of water in the mesh structure by ventilation took less than a few minutes at this mound height, which is presumably sufficient for the ability of Paleodictyon producers.
Deepsea bottoms are a very special environment — not only because they cover more than half of this planet. In the absence of light there is also no primary production other than bacterial chemosynthesis, whose fuels (H2S and CH4) are partly derived from organic matter. Otherwise the main food source consists of the breadcrumbs sinking down from the photic zone. Even these have usually passed through other stomachs, before they reached the bottom. So food at the deepsea floor is at premium not only in a quantitative, but also in a qualitative sense. Under such extreme conditions, one might expect a lowly diverse fauna of generalists. But the opposite is the case: deepsea dredges reveal levels of within-habitat diversity and differentiation that are reminiscent of tropical reefs and forests! To account for this paradox, the marine biologist Howard Sanders proposed the Time-Stability Hypothesis. It claims that within-habitat diversity depends on the permanence of environmental conditions through long periods of time, more than on levels of nutrient supply. Over time, diversity may be enriched by species that immigrate from shallower environments, but probably sympatric speciation is an equally important factor.
The ichonofossil Paleodictyon was discoveved in the Paleogene turbiditic deposits in the Dongying Sag, including two ichnospecies, namely, the Paleodictyon regular and Paleodictyon majus. The study on geochemical behavior of the wall rocks revealed that the dinosterane, a sign of marine transgression, was checked out. The both meant that Paleogene sedimentation in the Dongying Sag might be once affected by seawater.
Trace fossils record the behavior of animals at the very spot where they lived millions of years ago. Their growing interest derives from the intimate connection between ichnology and sedimentology and their combined relevance for paleoenvironmental reconstructions, basin analysis, and petroleum exploration. This definitive textbook by a renowned field observer and analyst of trace fossils concentrates on the most distinctive examples, mostly made by infaunal invertebrates in originally soft sediments. It covers the whole geologic column and ranges from deep-sea to shallow-marine and continental environments. Seilacher's Trace Fossil Analysis is designed to foster interpretative skills using the author's own iconic drawings. They are thematically grouped in 75 plates that form the core for the descriptive text and annotated references. A glossary of ichnological terms is also provided.
Ophiomorpha group trace fossils occur abundantly in a range of Eocene-aged deep-marine environments of deposition in the Basque basin, northern Spain. The morphology and dimensions of these trace fossils, observed in off-axis submarine lobe deposits, are discussed. The reported specimens display a highly organized and systematic burrowing behavior preserved on turbidite bed bases that display interconnecting Y-shaped (hexagonal-polygonal) morphologies. This observation, together with the cross-cutting relationship with tool marks, suggests construction of postdepositional agrichnial burrow networks. The networks probably harvested microbes that broke down cellulose-based organic matter providing an exploitable nutrient source for crustacean trace makers of Ophiomorpha. Therefore, the Ophiomorpha group–related traces discussed herein are postulated to represent an ethological response to changes in deep marine environmental conditions driven by global climate change during the early Paleogene, including the early Eocene hyperthermal events.
The graphoglyptid ichnogenus Paleodictyon has been alternatively interpreted as a foraging or farming trace; as a subsurface burrow for the habitation of one or more unknown organisms; the remains of a xenophyophore; and as the result of modular growth of an unknown organism. Graph theory and analysis of the geometry of the regular ichnospecies suggests that if the elements of Paleodictyon are interpreted as tunnels, then they are of extraordinary length relative to the size of any likely solitary tracemaker. In addition, because each vertex of the mesh is of degree three, any possible path through mesh requires revisiting in order to travel through the entire network; this makes the minimum path length even longer. These results suggest that it is unlikely that Paleodictyon is the result of subsurface burrowing.
-Stratinomic indications by trace fossils in Eocene to Miocene turbidites and hemipelagites of the Northern Apennines (Italy) -Ichnology has been only recently reappraised as a good tool for palaeoecological and palaeoenvironmental interpretations, although still few and partial data are nowadays available about tracemakers and their ethology. For these reasons detailed analyses focusing on the characterization of ichnofossil assemblages distributed within different deposits are indispensable. In turbidite and hemipelagite sediments of the Northern Apennines (Italy), early Eocene to late Miocene in age, 317 samples have been investigated, focusing on stratinomy and abundance in depositional units ("scisti varicolori", Scaglia, Bisciaro, "marnoso arenacea", Macigno and Arenarie di Monte Cervarola formations). This study points out the poorly known or undescribed trace fossils from this area and exhibits preliminary results about the relationships between infauna and sedimentation. Stratinomy allowed to recognize five types of trace fossil distributions, each taking account on burrow stratinomic value that reflects their position in the event bed: hypichnia (base of bed), endichnia (inside bed), epichnia (top of bed), exichnia (outside bed) and crossichnia (crossing event bed an overlying and/or underlying marly/silty beds). This work represents the base for further analyses that will focus mainly on the understanding of the relationship between burrow assemblages and sediment characteristics in foredeep basins. RIASSUNTO -Indicazioni stratinomiche dalle tracce fossili nelle torbiditi ed emipelagiti eocenico-mioceniche dell'Appennino Setten-trionale -Solo recentemente è stato riconosciuto il potenziale delle tracce fossili come strumento per le interpretazioni paleoecologiche e paleoambientali, ma i dati a disposizione circa la distribuzione e la sinecologia degli icnotaxa sono ancora scarsi. Per questo motivo è indispensabile eseguire studi volti innanzitutto a caratterizzare le varie icnocenosi distribuite all'interno dei vari contesti sedimentari. In tale ambito si inserisce questo lavoro che ha preso in esame le icnoassociazioni preservate nei depositi eocenico-miocenici torbiditici ed emipelagitici delle formazioni degli "scisti varicolori", della Scaglia (Scaglia Rossa, "scaglia variegata" e Scaglia Cinerea), del Bisciaro e delle formazioni silicoclastiche del Macigno, delle Arenarie del Monte Cervarola e della formazione "marnoso arenacea" affioranti in Ap-pennino Settentrionale. Le analisi, svolte su 317 campioni raccolti in 30 diverse località rappresentative, hanno consentito di caratterizzare tassonomicamente le icnocenosi e di comprendere preliminarmente le relazioni stratinomiche delle tracce fossili nei depositi gravitativi. Gli icnotaxa possono essere raggruppati in 5 gruppi stratinomici che riflettono sostanzialmente la loro distribuzione rispetto allo strato-evento: hypichnia, endichnia, epichnia, exichnia e crossichnia. Questo lavoro rappresenta un contributo preliminare alla descrizione delle icnocenosi caratterizzanti l'Appennino Settentrionale e getta le basi per ulteriori studi volti a comprendere a fondo le relazioni che inter-corrono tra tracce fossili e depositi torbiditico-emipelagici, così da incrementare le potenzialità dell'icnologia negli studi paleoambientali di mare profondo.
Taphonomic features of 156 graphoglyptids and other trace fossils preserved as hypichnia of thin-bedded turbidites in Oligo-Miocene flysch of the northern Apennines (central Italy) were analyzed. Two biogenic taphonomic categories—deformation and elongation—were produced in hemipelagic mud by the behavior of endobenthic organ-isms. Deformation includes such features typical of bulldozing and burrowing as twisting, squeezing, tilting, thickening, and widening. Elongation is considered a primary biogenic character controlled di-rectly by the tracemaker. Taphonomic features induced by such physical agents as currents and creep usually developed unidirec-tionally and include stretching, straightening, smoothing, bending, tapering, thickening, and thinning. These features, associated with hundreds of microgrooves (5–10 per 0.01 m 2) interpreted as mud-current lineations, suggest that currents were active and produced deformational structures of fluting before, during, and after the bio-genic activity. Preservation of such delicate structures recognizable at different levels is particularly noticeable when a thin layer of fine material settled by suspension, molding all structures and producing a cemented film. Deformational structures may be particularly well preserved in thin-bedded (3–6-cm-thick) and fine-grained calcarenitic turbidites as in diluted turbulent flow deposits that fringed the iso-lated Verghereto High. Activities of epi-and infaunal communities in this area are also exceptionally well preserved. Physical tapho-characters of graphoglyptids are interpreted in two ways: (1) as true tool marks produced in mud by a tractive water mass preceding sand deposition by turbidite flows, or (2) as structures inherited from pre-turbidite phases. Taphonomic analysis in deep-sea deposits, therefore, is a promising methodology to resolve the preservational state of trace fossils above and below the soles of turbidites.
Distribution of trace fossils in flysch sediments is in great part conditioned by tiering; that is, the vertical partitioning of trace-producing organisms below the sediment-water interface. Ichnologic studies in the Guipúzcoan flysch (Upper Albian-Lower Eocene), northern Spain, show that tiering in flysch sediments is strongly controlled by sediment character, mode and rate of deposition, and degree of oxygenation of pore waters. Depending on the mode of deposition, trace-fossil tiering in flysch developed and was preserved in two radically different styles: (1) In event layers (chiefly turbidites), tiering is preserved without secondary distortion, owing to synchronous colonization and the lack of vertical ascent through time. Vertical tiering structure depends primarily on sediment composition, sequence and thicknesses of structural divisions, and oxygen profile. Variations in tiering are interpreted to reflect the particular oxygen tolerances, penetration potentials, and nutritional requirements of tracemakers; (2) In background sediments (hemipelagites and pelagites), tiering resulted from successive colonizations that were influenced by background sedimentation rates, sediment composition, and oxygen levels of pore waters. Tiering of actively or passively filled burrows is reflected by complex ichnofabrics and the superposition of different tiers by ascension. Tiering structure was frozen upon deposition of superjacent event layers. The original tiering of graphoglyptids (open burrows) may be reconstructed from their cross-cutting relationships on turbidite soles.These contrasting styles of tiering development are characteristic of flysch and other sediments composed of alternating event and background deposits.
A concentration of exceptionally well-preserved large tubular foraminifera occurs on a specimen from the sole of a sandstone bed from the Eocene Zumaya flysch. The foraminifera were probably washed out from the sediment by a weak bottom current, orientated and concentrated in a pre-existing depression on the ocean floor. Fortunately, subsequently deposited turbidite sand, which forms the host bed, only disturbed the fossils to an infinitesimal degree.
Depositional systems in deep-water basin margins can be classified on the basis of grain size and feeder system into 12 classes: mud-rich, mud/sand-rich, sand-rich, and gravel-rich "point-source submarine fans;" mud-rich, mud/sand-rich, sand-rich, and gravel-rich "multiple-source submarine ramps;" and mud-rich, mud/sand-rich, sand-rich, and gravel-rich "linear-source slope aprons." The size and stability of channels and the organization of the depositional sequences decreases toward a linear source as does the length:width ratio of the system. As grain size increases, so does slope gradient, impersistence of channel systems, and tendency for channels to migrate. As grain size diminishes, there is an increase in the size of the source area, the size of the depositional sys em, the downcurrent length, the persistence and size of flows, fan channels, channel-levee systems, and in the tendency to meander and for major slumps and sheet sands to reach the lower fan and basin plain. The exact positioning of any one depositional system within the scheme cannot always be precise, and the position may be altered by changes in tectonics, climate, supply, and sea level. However, the models derived from each system are sufficiently different to significantly affect the nature of petroleum prospectivity and reservoir pattern. Understanding and recognizing this variability is crucial to all elements of the exploration-production chain. In exploration, initial evaluations of prospectivity and commerciality rely on the accurate stratigraphic prediction of reservoir facies architecture, and trapping styles. For field appraisal and reservoir development, a similar appreciation of variability aids reservoir description by capturing the distribution and architecture of reservoir and nonreservoir facies and their impact on reservoir delineation, reservoir behavior, and production performance.
Within the Aberystwyth Grits the trace fossils Paleodictyon and Squamodictyon occur with marked preferred orientation on the soles of turbidite sandstones. Orientation of the tunnel systems can be used to determine bottom current trend during the period between turbidite deposition. Over much of the area, trace fossil orientation and sole marks are both commonly parallel with the SSW-NNE trough axis. However, in the S within thicker bedded, more proximal parts of the succession trace fossils are oriented axially but sole marks indicate downslope marginal supply from the W. This reflects the pattern in some modern oceans where turbidity currents transport sediment down slope and bottom currents contour axially. Locally, sole marks are oriented SW-NE but trace fossils are aligned E-W and are interpreted as reflecting bottom currents oblique to the trough axis.- from Authors
Nearly a century of descriptive work on graphoglyptids has yielded little information on the biologic affinity of tracemakers or the ecologie significance of these peculiar spiral, meander, and network trace fossils. Most graphoglyptids were constructed by shallow‐burrowing invertebrates that belonged to stable, diverse, deepsea ecosystems; however, the functional role(s) of the tracemakers, in both ancient and modern ecosystems, is virtually unknown. Do the organisms producing graphoglyptids trap meiobenthos or cultivate bacteria/fungi; or, could the varied burrow morphologies indicate many different functional roles, perhaps including caching of seasonally abundant food, utilization of dissolved carbon, chemosymbiosis, or maintenance of multifunctional nests? In terms of the Phanerozoic development of deepsea trace fossil assemblages, was the apparent enrichment of ichnotaxa (including graphoglyptids) in the late Mesozoic linked to the appearance and proliferation of angiosperms; or, did changes in ocea...
This chapter discusses evolution of trace fossil communities. Paleontological community studies suffer from the inadequacies of the fossil record: (a) the ratio of fossilizable shell bearers to soft-bodied animals is variable and decreases with depth, (b) fossil assemblages represent time intervals of unknown duration, (c) post-mortem transport of skeletal remains has often admixed elements from alien habitats, and (d) digenetic solution tends to selectively eliminate parts of the original shell assemblages. These biases are considerably reduced in the truce fossil record, which includes the products of soft-bodied as well as shell-bearing organisms, is less affected by digenesis and not affected at all by sedimentary displacement. The structure and diversity of soft-bottom communities, as expressed in the trace-fossil record, is suggested to have evolved in the following successive phases. (1) pioneer phase with emphasis on trophic flexibility and large body size, (2) saturation phase with emphasis on trophic diversification, behavioral optimization and body size diminution to accommodate more species and increase their evenness within the limits of a given and predictable food resource, and (3) co-evolution phase with emphasis on the behavioral diversification of tropically equivalent species.
Facies representing eight deltaic environments are recognized in the Mansfield Formation (Pennsylvanian: Morrowan) and Dugger Formation (Pennsylvanian: Desmoinesian) of Indiana. These facies are interpreted as: 1) lower interdistributary bay, 2) middle interdistributary bay, 3) upper interdistributary bay, 4) tidal flat, 5) distributary-mouth bar, 6) crevasse splay, 7) active channel fill, and 8) floodplain and lacustrine. Despite some overlap, each facies is characterized by a specific assemblage and diversity of trace fossils.-from Authors
Thick sediment accumulations in deep water provide a new target in the search for oil. The Laurentian fan is a large, deep-sea fan in the western N Atlantic, and has been the major depocenter off Nova Scotia since at least the early Tertiary. The main development of the present depositional and erosional fan morphology in the past 2 to 3 m.y. was closely related to onshore glacial history. The slope above the fan has been the site of rapid sedimentation and consequent slumping. A network of tributaries on the upper fan appears to feed 3 main channel systems. These channels meander widely across the lower fan, then die out abruptly and pass into a lobate suprafan. The channels contain thick, coarse gravels which should produce good reservoir bodies. Fine-grained sediments were more important in fan construction. Interbedded turbidites, contourites, and hemipelagites are present. The recognition of structural sequencies and fabric types in the fine-grained turbidites can be used to characterize particular parts of the fan, which should prove useful in future hydrocarbon exploration. -from Author
Sedimentology, geochemical and ichnological analyses of the Guipuzcoan Flysch suggest that dissolved oxygen levels control the size of the preturbidite trace fossils on turbidite bed soles. The limits to which different traces tolerate low oxygen conditions correspond to their vertical tiering, ie, deeper-tier ichnotaxa also range into less oxygenated areas than higher-tier forms. Not all traces, however, follow this rule (eg Paleodictyon minimum and Helminthorhaphe), probably because their producers had wider oxygen tolerances. -from Author
Shallow water late Precambrian and Early Cambrian sequences have yielded not only shallow water trace fossils but also many examples of traces typical of later deep water deposits. Significant colonization of the deep oceans by trace making animals was, however, delayed until the Early Ordovician. There followed a gradual increase in ichnogeneric diversity through much of the Phanerozoic, with an acceleration from the Cretaceous through the Tertiary. The apparent migration of deep water forms from their origins in shallow water out to the deep sea was accompanied by their virtual disappearance from shallow water, thereby providing an early example of "retreat'. -from Authors
Describes a basin, filled by a thick sequence of Recent hemipelagic muds and turbiditic sands, silts and muds. The slopes, which are strongly eroded, are locally covered by a thin layer of recent hemipelagic muds. Many biogenic tracers occur in all muddy deposits. Two main ichnofacies are evidenced; a deep slope ichnofacies and a deep plain ichnofacies. The distribution of biogenic traces is probably controlled by the greater food supply on the slopes. -from Author
Depositional system in deep-water basin margins can be classified on the basis of grain size and feeder system into 12 classes: mud-rich, mud/sand-rich, sand-rich, and gravel-rich [open quotes]point-source submarine fans,[close quotes] mud-rich, mud/sand-rich, sand-rich, and gravel-rich [open quotes]multiple-source submarine ramps;[close quotes] and mud-rich, mud/sand-rich, sand-rich, and gravel-rich [open quotes]linear-source slope aprons.[close quotes] The size and stability of channels and the organization of the depositional sequences decreases toward a linear source as does the length:width ratio of the system. As grain size increases, so does slope gradient, impersistence of channel systems, and tendency for channels to migrate. As grain size diminishes, there is an increase in the size of the source area, the size of the depositional system, the downcurrent length, the persistence and size of flows, fan channels, channel-levee systems, and in the tendency to meander and for major slumps and sheet sands to reach the lower fan and basin plan. The exact positioning of any one depositional system within the scheme cannot always be precise and the position may be altered by changes in tectonic, climate, supply, and sea level. The models derived from each system are sufficiently different to significantly affect the nature of petroleum prospectivity and reservoir pattern. Understanding and recognizing this variability is crucial to all elements of the exploration-production chain. In exploration, initial evaluations of prospectivity and commerciality rely on the accurate stratigraphic prediction of reservoir facies, architecture, and trapping styles. For field appraisal and reservoir development, a similar appreciation of variability aids reservoir description by capturing the distribution and architecture of reservoir and nonreservoir facies and their impact on reservoir delineation, reservoir behavior, and production performance. 161 refs., 19 figs., 4 tabs.
Thick sediment accumulations in deep water provide a new target in the search for oil, and require an innovative approach to hydrocarbon exploration. The Laurentian fan is a large, deep-sea (2000 to 5000 m) fan in the western North Atlantic, and has been the major depocenter off Nova Scotia since at least the early Tertiary. The main development of the present depositional and erosional fan morphology in the past 2 to 3 m.y. was closely related to onshore glacial history. The slope above the fan has been the site of rapid sedimentation and consequent slumping. A network of tributaries on the upper fan appears to feed three main channel systens incised up to 800 m between broad asymmetric levees. These channels meander widely across the lower fan, then die out abruptly and pass into a lobate suprafan. Differences between the Laurentian fan and typical fan models result, in part, from the muddy nature of the sediment and the supply system. The channels contain thick, coarse gravels which probably grade distally into sandy lobes. Both should produce good reservoir bodies with suitable source and trapping mechanisms. Fine-grained sediments were more important in fan construction. Interbedded turbidites, contourites, and hemipelagites are present in the late Quaternary-Holocene sequence. The distribution of these sediments and, in particular, the recognition of structural sequences, textural trends, and fabric types in the fine-grained turbidites can be used to characterize particular parts of the fan environment. The development of this approach should prove useful in future hydrocarbon exploration.
The postdepositional sole trails of Flysch psammites occur only in thinner beds up to a thickness particular to each species. This proves instantaneous deposition of the individual beds, as postulated by the turbidity-current theory. The majority of the sole trails are predepositional mud burrows washed out and sand cast by turbidity currents. Thus erosion of an unusual type must have preceded every turbidite sedimentation.
Flysch sediments of Early Cretaceous to Early Eocene age which crop out in Guipuzcoa, North Spain, on the southern shores of the Bay of Biscay, have been analysed with particular reference to lithology and directional plus non-directional sedimentary structures. This analysis, which incorporates more than 500 palaeocurrent measurements, confirms that deposition occurred in an E—W-oriented trough. The sediments consists of turbidity current transported sandstones and siltstones, together with mudstones and limestones. Several slump sheets are also present.During the Early Cretaceous, most of the turbities were transported axially from the east but some turbidites, and perhaps also a slump sheet, were marginally derived from the north. In the Late Cretaceous, turbidites were only being axially transported, mostly from the east, and the trough appears to have been at its widest. The trough narrowed during the Paleocene, so that it was probably at its most restricted by the Early Eocene, when southerly flowing turbidity currents deposited a thick (> 600 m) deep-sea sand fan extending from the southeastern Bay of Biscay to the present-day coast.The changes in regional palaeogeography can be interpreted in terms of a phase of Cretaceous distention, followed by Paleocene/Eocene compression, perhaps leading to Late Eocene/Oligocene continental collision with folding here and in the adjacent Pyrenees.The southerly palaeoslope of the Eocene sand fan contrasts with the northerly slope of the present-day continental shelf, thus confirming that the form of the southeastern Bay of Biscay, including the Cap Breton Canyon, is of post-Early Eocene age.
About 100 deep-sea photographs revealed discoidal shaped objects several centimeters in diameter with marked hexagonal symmetry lying on sediment-covered step-like levels of the wall of the rift valley of the Mid-Atlantic Ridge at latitude 26°N between depths of 3200 and 3700 m below sea level. The characteristics of the discoidal shaped objects, including the symmetry and inferred individual growth stages, are closest to compressed forms of a hexactinelid sponge adapted to an unconsolidated sediment substrate.
A diverse assemblage of trace fossils has been collected from Lower Eocene to Upper Miocene strata during regional geological mapping of 75,000 km of the Makran Range of southeastern Iran. Almost all are excellently preserved and this allows detailed descriptions, which in some cases can be used as a basis for taxonomic revisions of much used but inadequately analysed ichnogenera.27 ichnogenera have been identified and 25 ichnospecies described. These ichnotaxa include forms which are: straight, un‐branched (Planolites), straight, unbranched but twisted around a horizontal axis (Helicorhaphe), straight, branched (Chondrites, Palaeophycus, Thalassinoides), winding unbranched (Scolicia, Subphyllochorda, Taphrhelminthopsis), meandering or winding branched (Acanthorphaphe), spirals (Spirorhaphe, Spirophycus), networks (Desmograpton, Megagrapton, Paleodictyon, Urohelminthoida), rosettes (Glockerichnus, Lorenzinia) and spreite (Phycosiphon). There are also pellet lined burrows (Ophiomorpha) and rare unbranched vertical burrows (Skolithos).Descriptions are given of some 25 ichnospecies but three ichnogenera (Nereites, Paleodictyon, Urohelminthoida), are subjected to more detailed treatment, with taxonomic revision. All examples of Nereites with a sinuous or winding habit are placed in N. jacksoni Emmons 1844, to separate them from those with tight meanders and spirals for which N. cambrensis Murchison 1839 and N. macleayii Murchison 1839 are available. 6 ichnospecies of Paleodictyon are described and it is recognised that there is considerable gradation in mesh and string size, with significant overlap in the dimensions of these parameters between some ichnospecies where they are used as the main or sole diagnostic criteria. Consequently, the diagnosis of P. carpathicum (Matyasovsky, 1878) is emended to include all regular equidimensional to elongate hexagonal meshes with maximum length 3–10 mm and string diameter 0.1–2.5 mm. As a result, some examples of the following are placed in synonomy with it: P. majus Mene‐ghini 1879, P. miocenicum Sacco 1886, P. regulare Sacco 1886, Glenodictyon caucasicum Papp 1910, P. chattoni Pugin 1955 and P. carpaticum Vialov and Golev 1964. A detailed analysis shows no consistent difference between Urohelminthoida appendiculata (Heer 1877) and U. dertonensis Sacco 1888, so they are united under the former, which has priority, and an emended diagnosis is given.The sequences containing the trace fossils occur in a series of tectonic slices bounded by reverse faults. Stratigraphic position and correlation between these slices is based on detailed paleontological and, more particularly, micropaleontological determinations.The oldest sequence, comprising the Zaboli Unit is Eocene in age and shows a transition from trace fossil barren shelf carbonates to deep water turbidite sandstones and shales containing: Acanthorhaphe, Desmograpton, Helminthoida, Lorenzinia, Paleodictyon, Spirophycus, Spirorhaphe, Taphrhelminthopsis and Urohelminthoida.The Darban, Mosri, Shirinzad, Ruk, Angohran and Shahr Pum units vary in age within the range Middle Eocene to Lower Miocene and consist of sandstone‐shale turbidite sequences thousands of metres thick and have together yielded the following ichnogenera: Chondrites, Cosmorhaphe, Desmograpton, Gordia, Helicorhaphe, Helminthoida, Lorenzinia, Megagrapton, Paleodictyon, Phycosiphon, Scolicia, Spirorhaphe, Subphyllochorda and Urohelminthoida.The Mashkid, Roksha, Jarut, Ghasr Ghand and Band‐e Chaker units vary in age within the range Upper Eocene to Upper Miocene and comprise deeper water turbidite sequences passing upwards into clastic shelf deposits including deltaic, fluvialite, swamp and emergent facies. The turbidites contain: Paleodictyon, Spirorhaphe, Subphyllochorda and Taphrhelminthopsis, while the shallow water sandstones have: Chondrites, Glockerichnus, Ophiomorpha, Palaeo‐phycus, Planolites, Skolithos and Thalassinoides.The Jaghin and Sahan Tang units are of Miocene age and consist of shallow water clastic deltaic sequences with Nereites, Palaeophycus, Planolites and Skolithos.The total number of ichnogenera now known from Miocene turbidites is at least 35 and many of these have also been recorded from the present‐day deep oceans. This suggests that, with further research, trace fossils will probably prove to be at least as abundant and diverse in such environments in the Neogene and Quaternary as in the Paleogene. The occurrence of many forms in the present day oceans should allow deductions on the producers of the more complex and distinctive traces which will be applicable to Tertiary and older examples.
The most extensive ichnofauna yet recorded from a deep water Lower Palaeozoic sequence occurs within the distal turbidites of the Lower Silurian Aberystwyth Grits Formation of Central Wales.
The strata contain an abundant assemblage comprising 25 ichnogenera: Asteriacites, Bergaueria, Chondrites, Cochlichnus, Cosmorhaphe, Glockerichnus, Gordia, Helicolithus, Helminthopsis, Helminthoida, Hormosiroidea, Lorenzinia, Megagrapton, Monomorphichnus, Neonereites, Nereites, Palaeophycus, Paleodictyon, Planolites, Protopaleodictyon, Spirorhaphe, Spirophycus, Squamodictyon, Subphyllochorda, Taphrhelminthopsis; 36 ichnospecies are described, three of which (Asteriacites aberensis, Helminthopsis regularis, Cosmorhaphe elongata) are new.
The inorganic sedimentary structures and trace fossils of some 418 sandstone beds were examined in detail; 16 per cent of the beds commence with Divisions A or B and 84 per cent with Division C of the turbidite sequence. This indicates a relatively distal environment, mainly receiving low velocity turbidity currents, and favouring trace fossil preservation. The most common traces were Helminthopsis, Paleodictyon, and Squamodictyon which were found on 46 per cent, 34 per cent, and 19 per cent of the beds examined.
Data from this, and other recently described sequences, confirms that there was a gradual increase in trace fossil diversity in the deep oceans throughout the Lower Palaeozoic, in contrast to the situation in shallow water shelf seas where a peak was reached as early as the Lower Cambrian.
The flysch of Paleocene to Eocene age outcropping in an almost unbroken cliff section at the Playa de San Telmo, Zumaya, North Spain, has been the subject of a quantitative sedimentological analysis. It is inferred that sedimentation commenced with deposition of a limestone‐red shale sequence below wave base and continued with proximal and then distal turbidite sandstones deposited in what may have been a gradually deepening trough. The trough was probably oriented approximately east‐west, parallel to the subsequent main tectonic trend. Sediment transport within the trough appears to have been essentially axial, with calcareous and siliceous sand derived from the east, but some siliceous sand was also laterally transported mainly from a land mass to the north.
The sediments contain an abundant and varied suite of trace fossils. Thus, with the depositional environment already defined sedimentologically, it was possible to critically examine the relationship between facies, trace fossil distribution and possible water depth. The facies variations were shown to be reflected in a changing ichnofauna. Spreite such as Zoophycos and Rhizocorallium were present in limestones apparently deposited not far below wave base. These traces are replaced by rosetted, winding and meandering forms in the more proximal turbidite facies. In the more distal facies spiral and patterned trace fossils appear, winding and meandering forms are common but Zoophycos, Rhizocorallium and rosetted traces are absent. It is inferred that these changes reflect faunal distribution on the sea floor rather than preservational factors.
Grazing trails are described from Lower Silurian laminated siltstones and shales at Quidong, southern N. S. W., Upper Silurian
quartz-rich greywackes (the Cookman Formation) at Cheshires Creek and uppermost Silurian greywackes at Gowan Green in central-western
N. S. W. The trace fossilsPaleodictyon and ?Gordia occur at Quidong, a larger variety ofPaleodictyon, Granularia and an unnamed branching track at Cheshires Creek, andCosmorhaphe at Gowan Green. The nature of preservation and the environmental significance of the traces are discussed. Comments on the
possible origin ofPaleodictyon are also presented.
Aus unter- und obersilurischen Sedimenten von Neu-Süd-Wales werden verschiedene Weidespuren beschrieben. In untersilurischen
Siltsteinen und Schiefern wurden bei QuidongPaleodictyon und?Gordia gefunden. Eine größere Varietät vonPaleodictyon, Granularia und eine unbenannt gebliebene verzweigte Spur konnten in den obersilurischen quarzreichen Grauwacken oder Cookman-Formation
von Cheshires Creek nachgewiesen werden. Aus Grauwacken von Gowan Green, die zum höchsten Ober-Silur gehören, stammtCosmorhaphe. Die Art der Erhaltung der Spurenfossilien und die aus ihnen zu ziehenden palökologischen und paläogeographischen Rückschlüsse
werden diskutiert. Die Entstehungsweise der viel umstrittenen, durch ihre oft regelmäßigen Netz-Muster gekennzeichneten Weide-SpurPaleodictyon wird ausführlich besprochen.
Bathyal benthic foraminifera and stable isotopes from the Caravaca and Zumaya sections of Spain, indicate that the mass extinction near the Paleocene/Eocene (P/E) boundary (upper planktic foraminiferal Zone P6a) was rapid, coinciding with a negative δ¹³C-shift of 2–4%., the onset of dark grey shale deposition and increased carbonate dissolution. Prior to the extinction event, diverse benthic foraminiferal assemblages and high δ¹³C values suggest the presence of a stable intermediate-deep watermass rich in oxygen and saturated in calcium carbonate in both Caravaca and Zumaya sections. After the extinction event, small finely agglutinated (Haplophragmoides, Glomospira) and thin-walled epifaunal taxa (Nuttallides truempyi) dominate in the North Atlantic, Zumaya section. This assemblage indicates sluggish circulation, bottom waters undersaturated in calcium carbonate and dysaerobic conditions. Low oxygen conditions prevailed for the succeeding 400 kyr and are characterized by 1–2%. fluctuations in benthic δ¹³C. In the western Tethys, Caravaca section, infaunal taxa (“buliminids”) dominate after the extinction event and prevailed through the succeeding 400 to 450 kyr of decreased δ¹³C values, indicating low oxygen conditions.
An analysis of 71 samples from the Zumaya Section of northern Spain ranging in age from Cenomanian to lower Eocene enabled us to calibrate the biostratigraphic ranges of Deep-Water Agglutinated Foraminifera (DWAF) to the standard planktonic foraminiferal zonal schemes. Comparison with the standard Geroch and Nowak zonation of DWAF provides further evidence for the supraregional validity of this zonation, as well as new information on the palaeobiogeography of many of the species first described from the Flysch Carpathians. The nominate taxa of six of the seven Turonian-Palaeocene DWAF zones defined by Geroch and Nowak (1984) were observed in their proper stratigraphic succession at Zumaya (the Ammobaculites problematicus, Uvigerinammina jankoi, Goesella rugosa, Hormosina ovulum gigantea, and Spiroplectammina spectabilis zones of Geroch & Nowak). Only the index taxon of the lower Paleocene Rzehakina fissistomata Zone was not observed, however this zone may be recognised based on alternate criteria (the last occurrence of Goesella rugosa). The benthic foraminiferal extinction at the Palaeocene/Eocene boundary is proposed as an alternate criterion to delimit the top of the Spiroplectammina spectabilis Zone / Analiza 71 próbek z profilu Zumaya w północnej Hiszpanii, obejmującego utwory od cenomanu do dolnego eocenu, pozwoliła na wyznaczenie zasięgów stratygraficznych głębokowodnych otwornic aglutynujących oraz na korelacje tych zasięgów ze standardową biozonacją opartą na otwornicach planktonicznych. Analizując zasięgi otwornic aglutynujących z tego profilu profilu potwierdzono uniwersalny charakter biozonacji zaproponowanej przez Gerocha i Nowaka (1984) oraz stwierdzono jej przydatność również dla obszarów pozakar-packich. Praca dostarcza także nowych danych z zakresu paleobiogeografii gatunków otwornic aglutynujących, opisanych z fliszu karpackiego. Badania potwierdziły następstwo stratygraficzne pięciu poziomów (Ammobaculites problematicus, Uvigerinammina jankoi, Goesella rugosa, Hormosina ovulum gigantea oraz Spiroplectammina spectabilis sensu Geroch & Nowak) opartych na gatunkach wyznaczonych jako przewodnie przez Gerocha i Nowaka (1984). Jedynie gatunek indeksowy dla dolnopaleoceńskiego poziomu Rzehakina fissistomata nie został znaleziony w badanym profilu. W pracy zaproponowano zastępcze kryterium do wyznaczenia poziomu Rzehakina fissistomata zanik gatunku Goesella rugosa. Zanik licznych gatunków otwornic bentonicznych na granicy paleocenu i eocenu może być dodatkowym kryterium do wyznaczenia górnej granicy poziomu Spiroplectammina spectabilis.
Thesis (doctoral)--Swiss Federal Institute of Technology Zurich, 1999.
The complex, highly patterned, invertebrate burrow systems known as "graphoglyptids" in ancient sedimentary rocks have now
been recovered in box cores of modern deep-sea sediment. Spiroraphe, Cosmoraphe, and Paleodictyon occur as grooves in the tops of washed cores, and they apparently were produced and maintained as horizontal tunnel systems
just a few millimeters below the sediment surface. These burrows, which are important as indicators of deepwater sedimentary
environments in ancient strata, have been predicted in the modern deep sea but have not been found there until now.
A xenophyophore found just below the surface of a box core of modern deep-sea sediment from the Japan Trench has a threadlike plasma body that extends through horizontal, anastomosing networks of organically bound sediment tubes (the organism's test). The tubes resemble somne of the polygonal networks of the trace fossil Paleodictyon. Such xenophyophores may be the makers of Paleodictyon, and the complex, regular geometry of Paleodictyon may be determined by the xenophyophore's anastomosing body shape.
Evolution and dispersal tology 16
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