FIGURE 2- - uploaded by Alfred Uchman
Content may be subject to copyright.
Paleogeographic map for the Middle Triassic (240 Ma; Scotese, 1997); arrow points to the study area. Continental areas are shaded; marine realms in white.
Source publication
We encountered a highly diverse ichnofauna within the deep-sea fan
deposits of the Upper Triassic Al Ayn Formation in Oman. It comprises
32 ichnogenera: 18 ichnogenera represent predepositional graphoglyptids
and other trace fossils that are preserved as casts onturbidite soles, and 14 ichnogenera represent postdepositional tracefossils that penetr...
Context in source publication
Context 1
... the Early Permian, a rift system developed between Gondwana, including the Arabian Plate, and the Cimmerian blocks to the east (Ziegler and Stampfli, 2001). Subsequent spreading starting in the Late Permian led to the formation of the Neo-Tethyan Hawasina Basin along the Ara- bian Platform (Fig. 2). The passive continental margin deposits comprise the Hamrat Duru Group ( Fig. 3; Blechschmidt et al., 2004). Continuous Middle-Late Triassic extension led to a subdivision of the Hawasina Ba- sin by the formation of the Misfah Platform, which separated the proxi- mal Hamrat Duru Basin from the Umar Basin ( Béchennec et al., 1990). ...
Citations
... Zoophycos ichnofacies is named after the homonymous ichnogenus and is generally developed in muddy deposits with oxygen deficiency and rich in organic matter from the outer shelf to bathyal zones, dominated by complex fodinichnial burrows with a low ichnodiversity (Seilacher, 1967(Seilacher, , 2007Frey and Pemberton, 1985;Buatois et al., 2002;MacEachern et al., 2007aMacEachern et al., , 2007bBuatois and M angano, 2011;Richiano, 2015;Bouchemla et al., 2023). However, throughout the Phanerozoic, Zoophycos occurs in a high variety of depositional settings, from stormdominated shallow-marine environments in the Paleozoic (e.g., Gaillard et al., 1999;Knaust, 2009a;Zhang, 2014;Zhang and Zhao, 2015;Zhang et al., 2015b;Li et al., 2017;Sedorko et al., 2018;Abasaghi et al., 2020;Bouchemla et al., 2021a), to outer shelf and deep-sea sediments in the Mesozoic and Cenozoic (e.g., Wetzel and Werner, 1981;Olivero, 1996Olivero, , 2003Wetzel et al., 2007;L opez-Cabrera et al., 2008;Kotake, 2014;Richiano, 2015;Monaco et al., 2017;Mekki et al., 2019;Belghouthi et al., 2020;Vinn et al., 2020;Bouchemla et al., 2023), with some rare exemptions (e.g., Giannetti et al., 2017). During the Cretaceous, Zoophycos was characterized by large and complex burrows with lobed spreiten, found generally in the outer shelf to deep-sea deposits with oxygendeficient interstitial waters (Olivero, 2003;Seilacher, 2007;Zhang et al., 2015b). ...
Early Cretaceous succession of the Oued Fodda Formation in the Ouarsenis Mountains (northwestern Algeria) is mainly composed of marl–limestone alternations, which are subdivided into four informal units (Units 1 to 4), based on distinct lithological, stratonomical, and ichnological features. The ichnological analysis reveals a low diversity of the trace-fossil assemblage, which is exclusively reported from Units 2 and 3. The ichnoassemblage contains six ichnotaxa (Chondrites intricatus, Ophiomorpha isp., Planolites isp., Thalassinoides isp., Zoophycos brianteus, and Zoophycos cauda-galli), among which Zoophycos and Chondrites are the most common elements of the assemblage and occur in different mud-rich substrates showing different bioturbation intensities. The development of Zoophycos in the middle part of Unit 2 shows a high degree of bioturbation (bioturbation index (BI) = 4). Zoophycos specimens are of large size, between 45 cm and 75 cm in width, which were interpreted to have formed in a lower offshore environment where the oxygenation amount was optimal, the sedimentation rates were low, and the benthic food was abundant on the seafloor. Toward the upper part of Unit 2, Zoophycos-bearing levels exhibit a less intense degree of bioturbation (BI between 1 and 2) in contrast to Planolites- and Chondrites-bearing levels which have a bioturbation index (BI) between 3 and 4. At these levels, Zoophycos displays relatively small, coiled to U-shaped spreiten, probably in response to stressful and dysoxic conditions prevailing in the water bottom. With improved oxygenation in a quiet lower offshore to shelf margin environment in Unit 3, the benthic organisms recovered, as represented by medium to large size Zoophycos in association with Ophiomorpha and scarce Chondrites burrows, even if the overall bioturbation intensity is very low. The combination of trace-fossil assemblage and lithofacies of the Oued Fodda Formation indicates relatively stable outer shelf environments below the storm wave base, which corresponds classically to the lower offshore to shelf edge environments, and the prevailing palaeoecological conditions are optimal and stressful for the benthic organisms.
... За виключенням рідкісних знахідок нірок Ophiomorpha у порівняно глибоководних морських відкладах [Ksiazkiewicz 1977;Tchoumatchenco & Uchman 2001], цей іхнорід поширений переважно в пост-пермських мілководно-морських породах [Pedrol de Freitas et al. 2020]. На підставі значного поширення систем нір та окремих нірок Ophiomorpha в цих відкладах, вони розглядаються як індикатори прибережно-морських умов, хоча як вже повідомлялося, вони відомі також у відкладах глибоководних підводних конусів виносу і турбідитах [Tchoumatchenco & Uchman 2001;Wetzel et al. 2007;Cummings & Hodgson 2010] та навіть континентальних породах [Merrill 1984]. В палеогенових відкладах офіоморфи часто трапляються у складі нереїтової іхнофації підводних конусів виносу [Uchman 2001]. ...
... Вірогідними продуцентами нірок Ophiomorpha є десятиногі ракоподібні [Frey et al. 1978;Tchoumatchenco & Uchman 2001;Wetzel et al. 2007;Cummings & Hodgson 2010;Pedrol de Freitas et al. 2020 та ін.]. Наразі, з палеогену північної окраїни Донбасу відома лише одна фаунула декапод, що супроводжується монографічним описом та зображенням фосилій [Likharev 1917;Chernyshev 1949]. ...
Eleven Fodinichnia, Pascichnia, and Domichnia ichnotaxa (Apectoichnus longissimus (Kelly et Bromley, 1984), cf. Conichnus isp., Gastrochaenolites isp., Gnathichnus isp., Macaronichnus segregatis Clifton et Thompson, 1978, Ophiomorpha nodosa Lundgren, 1891, Palaeophycus isp., cf. Rosselia isp., Skolithos linearis (Haldeman, 1840), Spongeliomorpha isp., and Thalassinoides isp.) were identified from seven sections of shallow marine sediments of the Buchak Formation (Lutetian, middle Eocene) located in Luhansk Oblast, eastern Ukraine. Traces of bioerosion on the contact surface between the Upper Cretaceous marls and the Buchak Formation indicate the development of the Trypanites Ichnofacies in conditions of high water activity with almost absent sedimenta-tion. Most of the sediments of the Buchak Formation in the study area was formed in the conditions of the Skolithos Ichnofacies, namely in lit-toral environments with significant water activity, to resist which organisms were forced to build burrow systems. Some time intervals were also characterized by a decrease in the activity of the water, during which the sands of the littoral and probably sublittoral zones were colonized by the trace-makers of Macaronichnus segregatis burrows. In places of mass accumulation of wood, the Teredolites Ichnofacies is recognized, which is characterized by the development of teredenid bivalves specializing in feeding on wood. The contact surface of the Buchak and Kyiv formations is a firmground with the Glossifungites Ichnofacies developed on its surface and under it, which was already functioning during the accumulation of Kyiv Formation sediments. This ichnofacies was characterized by high water activity and the presence of organisms capable of bioturbating relatively dense substrates. The origin of massifs and blocks of quartzite-like sandstones among the sands of the Buchak Formation of Luhansk Oblast and many other sections of eastern and northeastern Ukraine is not fully understood, but their hydrothermal genesis is most likely. The obtained data are of great importance for the reconstruction of the depositional environment of the middle Eocene sediments in eastern Ukraine.
... Comments: Thalassinoides is generally considered a facies-crossing structure that occurs in a wide environmental range; it is most commonly related to well-oxygenated, shallow marine deposits (e.g., Vinn et al., 2020;Bouchemla et al., 2020Bouchemla et al., , 2021, but it also occurs in deep-water environments (e.g., Wetzel et al., 2007). It is interpreted as a domichnion mainly produced by crustaceans Knaust, 2017). ...
... irregulare and Megagrapton submontanum, showing very low bioturbation intensity (BI = 0-1). Generally, this category of horizontal trace fossils requires a quiet and deep environment with very low hydrodynamics (Seilacher, 2007;Wetzel et al., 2007;Uchman and Wetzel, 2012;Wetzel and Uchman, 2012), ranging from bathyal to abyssal deposits. They are considered diagnostic elements of the Nereites ichnofacies, which occurs in deepmarine settings from the Mesozoic and Cenozoic strata. ...
The mixed siliciclastic-carbonate Teniet El Klakh Formation (Middle Jurassic, Bajocian) mainly consists of a monotonous, clay and fine-grained sandstone alternation with some intercalated carbonate beds. The trace fossil record displays moderate to high ichnological diversity with different behaviours, consisting of 28 ichnotaxa belonging to 23 ichnogenera: Arenicolites isp., Bolonia lata, Chondrites targionii, Chondrites isp., Circulichnis montanus, Curvolithus simplex, Diplocraterion paralellum, Glockerichnus isp., Gyrochorte comosa, Helminthopsis abeli, Lockeia isp., Megagrapton cf. irregulare, M. submontanum, Monomorphichnus cf. multilineatus, Neonereites cf. biserialis, Nereites isp., Ophiomorpha isp., Palaeophycus cf. striatus, P. tubularis, Palaeophycus isp., Planolites isp., Protovirgularia dichotoma, Protovirgularia isp., Rhizocorallium commune var. irregulare, Rutichnus irregularis, Skolithos linearis, Taenidium cf. serpentinum, and Thalassinoides suevicus. The distribution of these trace fossils in space and time is controlled by various environmental features, mostly referred to the accumulation of organic matter in softground substrate during short phases of low hydrodynamics in well-oxygenated environments, thus allowing the occurrence of abundant and diverse invertebrates frequently dominated by deposit-feeders. The integrated sedimentological and ichnological features suggest that the Teniet El Klakh Formation had been deposited in a storm-influenced continental shelf setting ranging from the lower offshore to the lower shoreface zones with fluctuating energy regime, corresponding to the archetypal and proximal Cruziana ichnofacies transitional to the Skolithos ichnofacies. The ichnological assemblage described herein is original and rather unique, since most of trace fossils are reported herein for the first time from the Ksour Mountains.
... За виключенням рідкісних знахідок нірок Ophiomorpha у порівняно глибоководних морських відкладах [Ksiazkiewicz 1977;Tchoumatchenco & Uchman 2001], цей іхнорід поширений переважно в пост-пермських мілководно-морських породах [Pedrol de Freitas et al. 2020]. На підставі значного поширення систем нір та окремих нірок Ophiomorpha в цих відкладах, вони розглядаються як індикатори прибережно-морських умов, хоча як вже повідомлялося, вони відомі також у відкладах глибоководних підводних конусів виносу і турбідитах [Tchoumatchenco & Uchman 2001;Wetzel et al. 2007;Cummings & Hodgson 2010] та навіть континентальних породах [Merrill 1984]. В палеогенових відкладах офіоморфи часто трапляються у складі нереїтової іхнофації підводних конусів виносу [Uchman 2001]. ...
... Вірогідними продуцентами нірок Ophiomorpha є десятиногі ракоподібні [Frey et al. 1978;Tchoumatchenco & Uchman 2001;Wetzel et al. 2007;Cummings & Hodgson 2010;Pedrol de Freitas et al. 2020 та ін.]. Наразі, з палеогену північної окраїни Донбасу відома лише одна фаунула декапод, що супроводжується монографічним описом та зображенням фосилій [Likharev 1917;Chernyshev 1949]. ...
Eleven Fodinichnia, Pascichnia, and Domichnia ichnotaxa (Apectoichnus longissimus (Kelly et Bromley, 1984), cf.Conichnus isp., Gastrochaenolites isp., Gnathichnus isp., Macaronichnus segregatis Clifton et Thompson, 1978,Ophiomorpha nodosa Lundgren, 1891,Palaeophycus isp., cf.Rosselia isp.,Skolithos linearis (Haldeman, 1840),Spongeliomorpha isp., and Thalassinoides isp.) were identified from seven sections of shallow marine sediments of the Buchak Formation (Lutetian, middle Eocene) located in Luhansk Oblast, eastern Ukraine. Traces of bioerosion on the contact surface between the Upper Cretaceous marls and the Buchak Formation indicate the development of the Trypanites Ichnofacies in conditions of high water activity with almost absent sedimentation. Most of the sediments of the Buchak Formation in the study area was formed in the conditions of the Skolithos Ichnofacies, namely in littoral environments with significant water activity, to resist which organisms were forced to build burrow systems. Some time intervals were also characterized by a decrease in the activity of the water, during which the sands of the littoral and probably sublittoral zones were colonized by the trace-makers of Macaronichnus segregatis burrows. In places of mass accumulation of wood, the Teredolites Ichnofacies is recognized, which is characterized by the development of teredenid bivalves specializing in feeding on wood. The contact surface of the Buchak and Kyiv formations is a firmground with the Glossifungites Ichnofacies developed on its surface and under it, which was already functioning during the accumulation of Kyiv Formation sediments. This ichnofacies was characterized by high water activity and the presence of organisms capable of bioturbating relatively dense substrates. The origin of massifs and blocks of quartzite-like sandstones among the sands of the Buchak Formation of Luhansk Oblast and many other sections of eastern and north-eastern Ukraine is not fully understood, but their hydrothermal genesis is most likely. The obtained data are of great importance for the reconstruction of the depositional environment of the middle Eocene sediments in eastern Ukraine.
... Helminthopsis is often considered as a pre-depositional pascichnion (Buatois and Mángano 2011) and feeding trace of polychaete annelids (Książkiewicz 1977), reported from shallow marine environments (Wetzel and Bromley 1996), but also frequent in deeper flysch facies (Uchman 1995(Uchman , 1998Wetzel et al. 2007;Cherif et al. 2021a). Helminthopsis ranges from the Cambrian (Crimes 1987) to the recent (Swinbanks and Murray 1981;Wetzel 1983a, b). ...
... The Bergaueria are abundant in this Ichnoassociation suggesting probably the presence of rich food favourising colonisation of opportunistic suspension feeding actinarians (see above for reference), dwelling or resting trace (domichnion or cubichnion) of sea anemones (e.g., Pacześna 2010) and reported from high-energy shallow (e.g., Książkiewicz 1977) to deeper marine environments. The presence of Phycosiphon is related to distribution of organic matter in the sediments, which is reflected by the orientation and geometry of this trace (Wetzel et al. 2007). The occurrence of Chondrites is occasional and rare, indicating probably well oxygenised to less anoxic bottom waters (Savrda and Bottjer 1994). ...
Forty-three ichnospecies belonging to 30 ichnogenera are described from the Upper Jurassic Argiles de Saïda Formation (north-western Algeria), which consists of mixed shallow marine siliciclastic-carbonate sediments. The ichnological analysis reveals that the majority of the ichnoassemblages are represented by non-graphoglyptid traces dominated by Bergaueria isp., Ophiomorpha isp., O. rudis, Neonereites biserialis, N. triserialis. Furthermore, Chondrites isp., Palaeophycus isp., Phycosiphon isp., Planolites isp., Protovirgularia isp., Scolicia isp. and Thalassinoides isp. are common ichnotaxa. Ancorichnus isp., Archaeonassa isp., Gordia isp., Helminthoidichnites isp., Helminthopsis isp., Nereites isp., Ophiomorpha annulta, Oravaichnium isp., Oravaichnium hrabei, Protovirgularia dichotoma, Rutichnus rutis, Thalassinoides suevicus are rare, whereas, Chondrites targionii, Nereites irregularis, Neonereites uniserialis, Ptychoplasma excelsum, Spongeliomorpha isp., Taenidium isp., Taenidium serpentinum, ?Tubulichnium isp. and Zoophycos isp. are rare to scarce ichnotaxa. The graphoglyptid assemblage has very low diversity with only three ichnotaxa which are Megagrapton isp., Megagrapton submontanum and Scolicia strozzii. The described ichnoassemblages are assigned to the Cruziana to Cruziana-Nereites ichnofacies transition.
... Re marks. -Thalassinoides oc curs in vari able ma rine en vi ron ments, com monly in shal low ma rine set tings (Palmer, 1978;Ar cher and Ma ples, 1984;Frey et al., 1984;Mángano and Buatois, 1991;Pem ber ton et al., 2001), but also at greater depths (Uchman, 1995(Uchman, , 1998Uchman and Tchoumatchenco, 2003;Wetzel et al., 2007). It is pro duced mostly by crus ta ceans and in ter preted as domichnia and fodinichnia (Frey et al, 1978;Schlirf, 2000). ...
... Re marks. -This is a non-ma rine and ma rine eurybathic trace, com mon also in deep-sea fa cies, in clud ing flysch (Chamber lain, 1971;McCann and Pickerill, 1988;Fillion and Pickerill, 1990;Uchman, 1995Uchman, , 1998Wetzel et al., 2007). Helminthoidichnites is com mon from the Pre cam brian (Narbonne and Aitken, 1990) to the Pleis to cene . ...
Trace fossils and lithofacies have been studied for the first time in the Numidian Formation (Upper Oligocene – Lower Miocene) of the Ouarsenis Mountains in Algeria to interpret their depositional environment. Twenty-two ichnogenera have been recognized in eight lithofacies of three main facies associations in four representative sections. Distribution of the trace fossils is depended on the facies. Most of them are dominated by post-depositional forms (62%) and occur in fine-grained, thin-bedded sandstones of facies F4. They belong to the Ophiomorpha rudis, Paleodictyon and the Nereites ichnosubfacies of the Nereites ichnofacies. The O. rudis ichnosubfacies is recorded in 1) medium- to very thick-bedded sandstones of the facies association FA1, interbedded with thinner sandstone beds of the facies F2 and F4 in the upper unit of the studied sections, which were deposited in the channel fill and levee-overbank environment, and in 2) medium- to thin-bedded sandstones of the facies association FA2 in the lower unit of the Kef Maiz and the Ain Ghanem sections, which were deposited in isolated narrow channels within the mud dominated part of the depositional system and occasionally fed with turbiditic sand. The Paleodictyon ichnosubfacies occurs in thin- to medium-bedded sandstones (FA2) of the lower units in the Ain Ghanem and Kef Maiz sections and the lowest part of the upper unit of the Kef Maiz section, which were deposited in channel margin or foremost channel-to-levee-overbank areas. The Nereites ichnosubfacies is recorded in thin-bedded sandstones (FA2), which were deposited in crevasse-splays or small lobes on basin floor invaded occasionally by turbidites in the background of pelagic and hemipelagic sedimentation.
... Thalassinoides cross cuts Phycosiphon of the morphotypes Ph1, Ph2 and Ph3, but is cut by Ph4, Schaubcylindrichnus and Teichichnus. Representatives of Thalassinoides Ehrenberg, 1944 occur in deposits of variable, presumably shallow marine environments (Frey et al., 1984;Mángano and Buatois, 1991;Pemberton et al., 2001), but also in the deep-sea facies (Uchman, 1995(Uchman, , 1998de Graciansky et al., 1998;Uchman and Tchoumatchenco, 2003;Wetzel et al., 2007). They are produced mostly by scavenging and deposit-feeding crustaceans and interpreted as domichnia and fodinichnia (Frey et al., 1978;Frey et al., 1984;Bromley, 1996;Schlirf, 2000). ...
An uncommonly continuous Lower Jurassic (uppermost Sinemurian and Pliensbachian) section (Llanbedr (Mochras Farm) Borehole, Cardigan Bay Basin, UK) comprises hemipelagic calcareous mudstone, wackestone/siltstone and subordinate packstone/sandstone. Some beds show bigradational grading, and their sedimentary structures are typical of contourite drift facies. On the basis of the long-term persistence and stability of the currents that formed these deposits, sedimentation was likely controlled by thermohaline-driven geostrophic contour currents circulating between the Boreal ocean and Peri-Tethys through the narrow and relatively deep Cardigan Bay Basin (Cardigan Bay Strait). Trace fossils are strongly dominated by Phycosiphon incertum, which was produced by opportunistic colonizers. Thalassinoides, Schaubcylindrichnus and Teichichnus are common, accompanied by less common Zoophycos, Planolites, Palaeophycus, Trichichnus and dwelling structures such as cf. Polykladichnus, Siphonichnus and Skolithos. The ichnofabrics are usually simple, which results from generally high rates of deposition, unstable, water-saturated soft-ground substrate, and the domination of well-adapted Phycosiphon, but there are also cyclic appearances of more complex ichnofabrics with dwelling structures, reflecting more stable bottom conditions. A new detailed analysis of the core has allowed cycles to be distinguished based on combination of ichnological and sedimentological features, pointing to distinct cyclicity of oceanographic mechanisms influenced by orbital forcing and driving the inferred fluctuations in benthic life conditions, controlled mainly by variation in contour current intensity and oxygenation of bottom water reflected by trace fossils. The ichnological cycles show four-order hierarchy, which can be attributed to the orbital cycles: precession and obliquity (4th order), short eccentricity (3rd order), and long eccentricity (2nd order). The longest (~ 2.5 My) 1st order cyclicity is attributable to the longer ‟grand orbital cycles” (period related to the Earth–Mars secular resonance), with long-term impacts on palaeoclimatic and oceanic circulation dynamics, and is recorded in large-scale changes in ichnodiversity, correlating with long-term changes of clay minerals and carbonate content. Possibly, there is also ~9 Myr cyclicity, expressed in observed modulation of frequency of precession cycles by eccentricity. Harmonic analysis of the cyclicity gives high confidence of orbital signals and allows refined estimation of duration of the Pliensbachian (~8.4 Myr) and the jamesoni (~2.8 Myr), ibex (~ 2.0 Myr), davoei (~ 0.47 Myr), margaritatus (~ 2.33 Myr) and spinatum Zone (~ 0.8 Myr) with an overall stable sedimentation rate of 4.5–5.1 cm/kyr. Obtained durations show improved fit between 2nd–4th and 1st order cycle and removes the problem of an anomalously long duration and resulting much lower sedimentation rate for the spinatum Zone, previously obtained by other methods. A higher diversity of trace fossils is noticed in intervals enriched in smectite; most likely, this clay mineral occluded pore spaces and limited the competition from the opportunist Phycosiphon makers, allowing development of other, more specialized forms. The continuous, expanded ichnological record of deep-water hemipelagic/contour drift sediments is sensitive to climatic and oceanographic changes controlled by orbital cycles. The Cardigan Bay Strait played an important role in the Early Jurassic (at least Pliensbachian) oceanic circulation, providing a major link between the northern and southern part of the Laurasian Seaway (and in general between the Boreal and Peri-Tethys domains), funneling currents flowing from the north to the south.
... Helminthopsis is considered as a pre-depositional pascichnion (Buatois and Mángano, 2011) and often as an example of a repichnion. It is considered also as a feeding trace of polychaete annelids (Książkiewicz, 1977), reported from shallow marine (Wetzel and Bromley, 1994) to deeper flysch facies (Uchman 1995;1998;Wetzel et al., 2007). ...
... Paleodictyon is a typical graphoglyptid (Fuchs, 1895;Seilacher, 1977), considered as agrichnion traces of probably vermiform organisms (Buatois and Mángano, 2013;Buatois et al., 2017). It is characteristic of the Nereites ichnofacies (Uchman, 1995;1998;Wetzel et al., 2007). ...
... In this work, in order to deduce the depositional setting of the studied area we provided a comparison of the findings with 18 published deep-sea trace fossil selected in the given references from the Eocene-Oligocene Grès d'Annot Turbidites (Philips et al., 2011), the Miocene Güneyce Formation (Nielsen et al., 2012), the Oligocene-Miocene Numidian Formation (Riahi et al., 2014), the middle Jurassic Ridang Formation (Zhang et al., 2008), the Miocene Marnoso-arenacea Formation (Uchman, 1995), the Valanginian-Hauterivian Upper Cieszyn Beds (Uchman, 2004), the Cretaceous Kodiak Formation (McCann and Pickerill, 1988), the Oxfordian Argiles de Saïda Formation (Cherif et al., 2015), the upper Triassic Al Ayn Formation (Wetzel et al., 2007), the Albian-Senonian Ropianka Beds (Książkiewicz, 1977), the Paleocene-Miocene Campo de Gibraltar Complex Turbidites , the Paleocene Pagliaro Formation (Uchman, Fig. 9. Block-diagram representing depositional model of the Tiaret Marl Formation and the corresponding ichnoassociation along the unit B. ...
In this research study, 27 ichnospecies belonging to 18 ichnogenera are described for the first time from the lower Miocene Tiaret Marl Formation (north-western Algeria), which consists of thin-to medium-bedded sandstones and marlstones, representing deep-sea fan facies. The sandstones contain the following ichnotaxa: Cardioichnus isp., cf. Chondrites isp., Ophiomorpha isp., Ophiomorpha annulata, Ophiomorpha rudis, Palaeophycus isp., cf. Planolites isp., Planolites montanus, Zoophycos isp., Tisoa siphonalis, Helminthorhaphe isp., Scolicia isp., Scolicia prisca, Scolicia vertebralis, Cosmorhaphe isp., Desmograpton isp., Gordia isp., Helminthopsis isp., Nereites isp., Tubulichnium cf. incertum, Urohelminthoida appendiculata, cf. Megagrapton isp., Paleodictyon minimum, P. strozzii, P. majus, P. (Glenedictyum) miocenicum and P. maximum. The given ichnoassemblage is recorded for the first time from the Miocene of Algeria and assigned to the Nereites ichnofacies, which is typical of marine bathyal depth.
... The three ichnosubfacies are well recognised for both the Mesozoic and the Cenozoic deep-sea fan examples (e.g. Wetzel et al., 2007;Heard and Pickering, 2008) but their documentation seems problematic for the Palaeozoic (e.g. Benton, 1982;Pazos et al., 2015a, b;Fan and Gong, 2016), and some authors even consider that these ichnosubfacies are not entirely clear and not that widely used (MacEachern and Bann, 2020). ...
The Río Seco de los Castaños Formation (San Rafael Block) holds one of the few middle Palaeozoic (Silurian−Devonian) records worldwide of a Nereites-Dictyodora dominated ichnofauna with sedimentological features such as oscillatory and combined-flow deposits. This record is associated with microbial mats in fine-grained intervals between turbidite-like deposits documented above the storm wave base. In this work, a detailed sedimentological study permitted to divide the unit into two informal sections separated by an erosional unconformity attributed to a sea level fall. Prograding turbidite-like sand-grained deposits document gravitational turbulent flows. The tectonostratigraphic framework allowed to disregard a submarine fan, whereas the unconformity does not support an autocyclic deltaic evolution. Palaeocurrents and palaeoslope indicators to the SW suggest a high source area to the NE, that contrasts with the well-established E-W trend of most of the units of similar age in the Cuyania terrane. Deposition was probably deflected by subaqueous highs with the development of mini-basins most likely structurally controlled.
The ichnological analysis allowed to recognise ichnotaxa and intergradation cases between ichnospecies previously unknown for the unit, adding to the most diverse record of Dictyodora and Nereites in central-western Gondwana. Chondrites intricatus, Chondrites targionii, Chondrites? Dictyodora zimmermanni, and specimens resembling Dictyodora liebeana are recorded for the first time. Nereites missouriensis is documented in intergradation with Nereites jacksoni, whereas Dictyodora scotica is recognised in intergradation with Dictyodora atuelica and Dictyodora tenuis. A decrease in ichnodiversity throughout the section could be related to variation in environmental parameters between the lower and upper sections. The ichnofacies assignment is discussed in terms of ethological categories and ichnodiversity. Some of the defined ichnoassemblages are assignable to a non-standard record of the Nereites Ichnofacies, and one in particular to the Nereites Ichnosubfacies, while another shows some characteristics coincident with the Zoophycos Ichnofacies. A transitional case between ichnofacies for the ichnological content of the unit as a whole, as previously reported in other units, cannot be disregarded.
... Discussion: Thalassinoides is interpreted as dwelling and feeding structures of thalassinidean shrimps, especially callianassids (Knaust, 2017), and characterises a well-oxygenated shallowmarine environments (Palmer, 1978;Archer and Maples, 1984;Frey et al., 1984;Mángano and Buatois, 1991;El-Sabbagh et al., 2017;Vinn et al., 2020), but it also occurs in deep-water environments (Uchman and Tchoumatchenco 2003;Wetzel et al., 2007;Bendella and Ouali-Mehadji, 2014). However, the enormous studied burrows may be explained by the high availability of oxygen amount during the building of Thalassinoides (El-Sabbagh et al., 2017; present work). ...
The Upper Emsian to Frasnian Ia-Ib strata of the Marhouma area (or "km 30" outcrop), exposed in the Ougarta Range (SW Algeria) belong to the Chefar El Ahmar Formation. On the basis of distinct lithological and palaeontological features, this formation is subdivided into three members (Lower Marly Limestones Member, Middle Marly Limestones Member, and Upper Marly Limestones Member). The studied beds show low to moderate diversity of trace fossil assemblage which contains thirteen ichnotaxa: Chondrites intricatus, Chondrites isp., Chondrites cf. targionii, Circulichnis cf. montanus, Cochlichnus isp., Neonereites biserialis, Neonereites multiserialis, Nereites isp., Palaeophycus isp., Planolites isp., Thalassinoides isp., Zoophycos aff. cauda-galli, and Zoophycos isp. A. The two latter ichnotaxa are the most common trace fossils in the assemblage and occur at three different levels showing different bioturbation intensities. The first Zoophycos-bearing level (Zl 1) is characterised by an overall high bioturbation intensity reflecting a very high oxygenation rate and nutrient supply, allowing the development of large and dense Zoophycos specimens. The second Zoophycos-bearing level (Zl 2) has a considerable reduction of bioturbation intensity as compared to the previous level, with an abundance of Chondrites, which is probably due to radical palaeoecological changes that suggests dysoxic and stressful conditions. The third Zoophycos-bearing level (Zl 3) is characterised by an overall moderate bioturbation intensity. The distribution of trace fossils was influenced by lithology, sedimentation rate, energy level (storm events), bottom oxygenation, and nutrient supply. The lithofacies and trace fossils of the Chefar El Ahmar Formation both indicate a depositional environment fluctuating from the lower shoreface to lower offshore zone.
