Shoreface Settings Research Articles

Microbialitic third-order Rupelian cycles of the Kuwait Formation, and their global correlative surfaces

The microbialites identified in the Kuwait Formation (also known as the Kuwait Group) at the Jal Az-Zor escarpment were largely misclassified as calcrete beds. Through detailed geological field observations, five distinct microbial beds have been identified and are found to occur at the end of each depositional cycle. Over these cycles, three main facies have been identified; these are bioturbated cross-bedding, calcareous sandstones, and microbial facies. The combination of field and petrographic analyses indicates that these sequences are dominated by siliciclastic facies, with microbial facies primarily manifesting as thrombolites or laminites, with the former being more common. Mineralogical analysis of the microbial facies indicate that over 60% of this facies is composed of calcite, and energy dispersive spectroscopy measured a significant percentage of organic carbon that reached up to 39.3% wt. Scanning electron microscope imagery of the microbial facies identified filamentous bacteria and flagellates as the principal constituents of these microbial assemblages. The bioturbated cross-bedding facies is found to be deposited in an estuarine central bay, the calcareous sandstone facies is deposited in an estuary mouth bar system that transitions laterally into a shoreface setting, and the microbial facies is deposited in a peritidal setting. Strontium isotope (87Sr/86Sr) dating of the five microbial beds indicates that these beds were deposited at 33.99 Ma, 32.6 Ma, 31.5 Ma, 30 Ma, and 29 Ma, respectively, suggesting that the associated sequences are of a Rupelian 3rd order hierarchy. Our analysis correlates the Jal Az-Zor sequences with New Jersey's Oligocene oxygen isotope sequence boundaries and the La2004 obliquity nodes, suggesting a continued uplift rate during the Rupelian age at the studied area. This article challenges the assumption that the Oligocene success is absent in Kuwait and the surrounding region, opening the door for further assessment of these deposits.

Widespread Thalassinoides facies from the upper Silurian of South China: A case study from the northwestern Hunan Province, middle to upper Yangtze Block

The upper Silurian of South China records the first, and perhaps the only occurrence of widespread (spanning over 1400 km), thick to very thick bedded Thalassinoides facies (TVTFs) after the Late Ordovician mass extinction. However, the palaeobiological, palaeoecological features and potential significance of these facies are yet to be demonstrated. A case study at northwestern Hunan Province, middle to upper Yangtze Block, reports the occurrence of TVTFs in a storm dominated open marine succession of the upper Silurian Xiaoxi Formation, which can be further assigned to lower offshore, upper offshore, offshore transition to distal lower shoreface, and proximal lower to middle shoreface settings. The regular changes of bioturbation intensity and maximum penetrating depth from various settings suggest that local energy levels, especially frequency of storms could have controlled the development of Thalassinoides, while their burrow sizes were generally confined by population densities. The Thalassinoides facies could have been constructed by unknown crustaceans, which generally conducted a deposit-feeding strategy. The return of widespread TVTFs in the tropical oceans of South China during the late Silurian could reflect a restored primary productivity, an elevated oxygen level, and a final recovery of benthic ecosystem to pre-extinction level after the Late Ordovician mass extinction. TVTFs could have remarkably shaped the late Silurian benthic environment in view of their high abundance, large burrow sizes, nature of deep tiered burrow systems and a deposit-feeding strategy.

The new ichnospecies Teredolites solitarius and its taphonomy from the Cenozoic carbonate intervals of Kutch Basin, India

Teredinidae is a family of bivalves occupying a spatial range of brackish to open-marine benthic niches and a stratigraphic range from Jurassic to recent. The teredinid genus Kuphus occurs within the calcareous muddy stiffground to hardground as vertical to inclined calcareous tubes. The ichnogenera Teredolites and Apectoichnus encompass the borings generally produced by the teredinids/shipworms. In the Kutch Basin, solitary teredinid borings range from the Eocene to the Early Miocene. Each subvertical boring has a calcareous wall with growth annulations on its outer surface. These tubes do not display any homeomorphic exoskeletal character. Rather, they manifest the producer’s ethology of mechanical boring into the organic-rich stiffground to hardground substrates and sustenance through microbially mediated chemosymbiosis. A systematic ichnotaxonomy is presented here for the solitary ‘Kuphus tubes’ which are classified as a new ichnospecies: Teredolites solitarius. The taphonomic analysis of the borings is based on the size, shape, orientation, and composite secondary borings, which are used in ascertaining the depositional conditions and palaeoecology. Two distinct taphofacies, i.e. TS-A and TS-B, have been identified. The TS-A represents the in-situ vertical morphotype formed in a restricted intermittently brackish mud-dominated inner carbonate ramp setting. The TS-B represents the reworked borings redeposited along with other bioclasts in a storm-influenced lower to middle shoreface setting.

Foraminiferal Assemblages As Bioindicators In The Western Caribbean: Albuquerque Cay (Colombia)

Abstract The San Andrés Archipelago (Colombia) constitutes a biological hotspot for the Western Caribbean. However, expanding human populations and unrestrained exploitation of the natural resources jeopardize the sustainability of key ecosystems in most of the islands. We surveyed the benthic foraminiferal assemblages of Albuquerque Cay, a relatively isolated location in the archipelago, during an ecosystem monitoring expedition in 2018. Assemblages recorded from the lagoon and shoreface settings were characteristics of a typical Caribbean reef lagoon. Porcelaneous forms and genera that host algal symbionts, including Archaias, Amphistegina, Heterostegina, Laevipeneroplis, and Sorites, were common, as were smaller taxa, especially Quinqueloculina, Rotorbinella, and Cymbaloporetta were also found in variable proportions, while stress-tolerant and agglutinated taxa were scarce (Elphidium, Clavulina). Results suggest differences in the composition of the assemblages from both sandy cays and the reef lagoon settings, likely conditioned by hydrodynamic fluctuations and nutrient availability. Moreover, a preliminary survey of the FoRAM Index (FI) suggests moderate to good conditions for the environments of Albuquerque Cay, contrasting with estimations of the FI in other insular bodies of the area. Therefore, future studies in the archipelago could reinforce the great potential that foraminiferal assemblages have as bioindicators in this part of the Caribbean.

Environmental and taphonomic controls on the shell beds and fauna of the middle Miocene Chipola Formation of Florida, USA

Thick (2–10's m) and laterally extensive shell beds are common in the stratigraphic record, however, relatively little is known about their genesis since no single cause can explain the formation of these shell deposits. The goal of this study is to use lithologic, faunal, and taphonomic analyses to elucidate how the thick and laterally extensive shell beds of the middle Miocene Chipola Formation of Florida formed and became one of the most species-rich Cenozoic faunas in the western Atlantic Province. This study examined Chipola Formation outcrops at Alum Bluff, Cooter Bluff, and Farley Creek. Lithologic and trace fossil analyses indicate that the Alum Bluff shell bed represents an upper to middle shoreface setting, whereas the Farley Creek and Cooter Bluff shell beds represent lower shoreface and/or proximal offshore-transitional environments. Faunal data further support that Farley Creek and Cooter Bluff were deeper environments relative to Alum Bluff. Environmental preferences of most of the fauna indicate that all localities had normal, open-marine salinities with seagrass and unvegetated substrates. Samples are classified as within-habitat time-averaged assemblages, which were spatially averaged by various physical and ecological factors. Spatial averaging mixed the mosaic of communities that are represented by different types of substrate-controlled habitats within, but not across, significant variation in water depth. Finally, shell beds were accumulated by winnowing and/or high-energy events, such as storms, which produced the relatively thick, laterally extensive shell beds at each locality. Understanding the high diversity of the Chipola Formation is complicated and is likely best explained by multiple controls. Variation in alpha diversity among the localities is linked with differences in water depth as well as time and/or spatial averaging. The elevated diversity at each site was likely influenced by spatial averaging of habitats within a single depth zone, within-habitat time averaging, and poleward expansion of tropical taxa into the northern Gulf of Mexico due to environmental conditions associated with the middle Miocene Climatic Optimum. Similar poleward shifts of tropical taxa as those recorded in the Chipola Formation could hypothetically occur in the future as global temperatures and sea level rise. Future studies need to examine the biological changes associated with the middle Miocene Climatic Optimum to better understand the future impacts of ocean-climate change on marine communities.

An integrated workflow for seismic interpretation, petrophysical and petrographical characterization for the clastic Mangahewa reservoir in Pohokura gas field, Taranaki Basin, New Zealand

This research aims at delineating the main structural elements controlling the geologic setting of Taranaki Basin in New Zealand which in turn control the hydrocarbon potential of this basin and in particular of Pohokura Field which is considered one of the main gas-producing fields in the basin. This can be achieved utilizing the seismic data including three different marine seismic data sets covering 514.6 km2 with 12.5 m horizontal resolution. A synthetic seismogram and a set of seismic attributes were created to achieve this target. In addition, an integrated reservoir characterization study is applied to the Mangahewa reservoir in the Pohokura Field. This integrated characterization includes a detailed petrographical lithofacies analysis, well logging, and core analysis studies. Based on the petrographical study, eight lithofacies are described in Pohokura Field: 1) Laminated sandstone; 2) Massive sandstones; 3) Granular laminated sandstones; 4) Bioturbated sandstones; 5) Sand dominated and mud rich bioturbated sandstones; 6) Muddy bioturbated sandstone; 7) Laminated and rippled laminated mud rocks, and 8) Coal lithofacies which have been deposited in high energy shoreface setting. On the other side, the available well logging data includes caliper, GR (gamma-ray), sonic, neutron, density, and resistivity (shallow and deep resistivities). Logging interpretation enabled the estimation of the effective porosity (av. ∅ = 11.4%), hydrocarbon saturation (av. Shc = 62.87%), and the shale volume (av. VSh = 18.02%) with a total net pay thickness of all wells = 196 m. The available core data includes porosity, density, and permeability which are used to estimate the reservoir quality ranks; the effective pore radius (R35); the flow zone indicator, the discrete rock type (DRT), and the reservoir quality index (RQI). Considering the porosity, permeability, and the DRT values, the available core data are grouped into five reservoir rock types (RRTs) with the best reservoir quality assigned for the RRT1 (bioturbated, laminated and massive sandstones), while RRT5 has the lowest reservoir quality (muddy bioturbated sandstone, Granulated laminated sandstone, and laminated and rippled mudstone). This integrated study is applicable and extendable to the other basins in New Zealand and the southwestern Pacific. The proposed workflow is also applicable to the other analogs in the various basins elsewhere.

Dinosaur trackways from the Upper Cretaceous Nichkesai Formation near Mayluu Suu City, Southern Tien Shan Mountains, north-western Kyrgyzstan.

Trackways provide essential data on the biogeographic distribution, locomotion and behaviour of dinosaurs. Cretaceous dinosaur trackways are abundant in the Americas, Europe, North Africa and East Asia, but are less well documented in Central Asia despite extensive exposure of Cretaceous terrestrial sedimentary rocks in the region. Here we report the presence of bipedal, tridactyl dinosaur trackways near the city of Mayluu Suu, Jalal Abad Oblast, north-western Kyrgyzstan, the first discovery of dinosaur trace fossils within the country. The trackways are situated on a steep slope uncovered by a landslide around the year 2000 in a highly landslide-affected area. Photogrammetry is used to digitally analyse and conserve the trace fossils. We infer a shoreface setting for the trackways based on the locality sedimentology, discuss the identity of the track makers and highlight the potential for future trackway discovery in the area. This discovery contributes vital data to an otherwise sparse record on the spatio-temporal distribution of dinosaurs in Kyrgyzstan, and to the dinosaur trackway record of Central Asia.

Depositional and diagenetic controllers on the sandstone reservoir quality of the late cretaceous sediments, Gulf of Suez Basin

The complex depositional, burial, and diagenetic histories of the Late Cretaceous Nezzazat Group sandstones in Northeastern Africa present the main challenges with regard to reservoir quality. The quality of commercial reservoirs is maintained despite deep burial and the associated high temperature and pressure. The study presents an optimum integration of different data sets to address reservoir quality and reservoir performance controllers. The data set includes measured porosity and permeability, petrographic point-counting data, grain-size analysis, X-ray diffraction data, scanning electron microscopy, and porosity loss by compaction. The depositional controls on the reservoir quality are the facies, whereas the higher quality is found in the channel and upper shoreface settings. The coarse-grained sandstone is associated with better reservoir quality. The large intergranular porosity is the main porosity controlling the fluid flow. The massive and laminated sandstones are the best quality facies. The labile grains (feldspars and mica) control the permeability distribution. Whereas the secondary diagenetic controllers are the carbonate cementation that inhibited the effects of compaction. The siderite cementation has resulted in a micropore dominated and highly tortuous pore system. Total porosity has largely been preserved in the siderite-cemented sample but virtually eliminated in the dolomite cemented. A low volume of illite is associated with better reservoir quality. Whereas the better reservoir quality is associated with the abundant quartz cementation that protected the primary porosity from compaction. Compaction acts as a significant porosity loss factor during diagenesis. Authigenic kaolinite does not significantly affect the reservoir quality. The reservoir sensitivity to formation damage comes from the potential for fines (kaolinite, illitic clays, siderite, and pyrite) migration within the pore system that is readily mobilized by the fluid flow.

Ichnology in storm and fair-weather beds of an epeiric sea (Pimenteira Formation, Devonian, Brazil)

Trace fossils in storm-generated beds of shelf siliciclastic settings have been investigated mostly to understand the effect of waves in the infauna distribution. It is possible to identify a post-storm ichnofauna (with features attributable to Skolithos ichnofacies) and a resident ichnofauna (attributable to Cruziana ichnofacies) and this ichnologic signature can bring data about the frequency of storms (weak, moderate, or strong) in the lower shoreface zone. Thus, the ichnologic signature can be a key feature to understand the depositional setting in storm-dominated environments. An excellent unit to apply these concepts is the Pimenteira Formation (Eifelian-Frasnian, Parnaíba Basin), interpreted as result of deposition in a storm-dominated platform. In ichnological terms, this unit has a great ichnodiversity and abundance of ichnofossils, but few studies have integrated the trace fossil suites with a facies analysis to understand the storm influence during deposition. Thus, this study aims to (i) characterize storm-related ichnofaunas from the Pimenteira Formation, ParnaíbaParnaíba Basin, Brazil; and (ii) understand the paleocological controls in the colonization of shoreface beds in an epeiric sea. The ichnotaxons were grouped in four suites: Skolithos, Palaeophycus, Bifungiites, and Lophoctenium suites. The Skolithos suite characterizes the post-storm ichnofauna, while Palaeophycus, Bifungiites, and Lophoctenium suites characterizes the resident ichnofauna. The predominance of proximal Cruziana ichnofacies, associated with layers generated by storm events, attests colonization in shallow marine environment. However, the general absence of deposit-feeders indicates short term in the colonization window for the resident ichnofauna, implying in a shoreface setting moderately impacted by storms.

Guangyuanichnus majianus n. igen. n. isp., a large, complex burrow system from the Lower Devonian Pingyipu Formation of the northwestern Yangtze platform, South China

A large, three-dimensional burrow system with a maximum vertical extension of 34 cm and a maximum covering area of 40 × 50 cm is reported from the Lower Devonian Pingyipu Formation of the northwestern Yangtze platform, South China. The burrow system, erected as Guangyuanichnus majianus n. igen. n. isp., is composed of two elements, i.e., a basal part that consists of several arcuate burrows, and an upper part emerging from the distal part of each arcuate burrow, which consists of radial, horizontal to subhorizontal spreite bodies in multiple levels in the substrate. The morphologic and taphonomic features of the basal and upper parts, the comparison of ecological and behavioral characters as well as the resulting burrows among various groups suggest that the burrow system was probably constructed by an unknown group of deposit-feeding bivalves. These animals burrowed to a medium to deep tier in the shoreface setting, where they constructed the basal arcuate burrows, and extended the agile siphon far out of the burrow to systematically exploit surficial materials for consumption. The behavior of the tracemaker and resulting trace fossils closely resemble those of modern and ancient tellinacean bivalves, which most likely represents a behavioral convergence. G. majianus probably represents some of the earliest bivalves that occupied a relatively deep tier and conducted a siphon-feeding strategy, a functional innovation well prior to the radiation of siphon-feeding infaunal bivalves during the Mesozoic. The presence of G. majianus suggests that large, deep burrowers tended to cause more dramatic impacts in substrate properties than other major Paleozoic bioturbators, and that they could be responsible for the elevated environmental effects of bioturbation as has been observed in strata younger than the latest Silurian.

The paleoenvironmental significance of trace fossils from the Cárdenas Formation (Late Cretaceous, Maastrichtian) at Potrero del Carnero, San Luis Potosí, central Mexico

This paper documents the occurrence of Skolithos linearis, Planolites beverleyensis, and Thalassinoides isp. in the Cárdenas Formation (Late Cretaceous), southeastern San Luis Potosí, central Mexico. This is the second record of S. linearis for this lithological unit, while P. beverleyensis and Thalassinoides isp. are documented for the very first time in this formation. The ichnoassemblage is referred to the Cruziana Ichnofacies which, in concert with associated invertebrate body fossils (Exogyra costata), suggest a shoreface setting with moderate- to low-energy conditions and episodic storms.

Depositional framework and trace fossil assemblages of the Lower Triassic Montney Formation, northeastern British Columbia, Western Canada Sedimentary Basin

Hydrocarbon production from the Lower Triassic Montney Formation in northeastern British Columbia, occurs primarily from unconventional reservoirs consisting predominantly of fine-to coarse-grained siltstone beds. In this area, the lithostratigraphy of the formation is difficult to characterize due to the complexities associated with subtle grain-size variation, diminutive biogenic structures, lateral facies variability, and distribution of local discontinuities. Detailed sedimentologic and stratigraphic analyses are essential for understanding and refining the depositional models and stratigraphic framework of the Montney Formation. Based on detailed core examination focused on sedimentological, paleontological and ichnological characteristics, eleven lithofacies and three recurring facies associations are identified within the Lower Triassic Montney Formation in northeastern British Columbia. The lithofacies identified are interpreted to have been deposited in offshore, offshore transition and lower shoreface settings, along a storm-dominated mixed siliciclastic-carbonate ramp. Facies associations include FA(A): siliciclastic distal offshore transition to distal offshore; FA(B): mixed siliciclastic carbonate, storm-influenced offshore to offshore transition; and FA(C): storm-dominated siliciclastic offshore transition to lower shoreface. Trace fossil assemblages correspond to a stressed Cruziana Ichnofacies, and are overall characterized by low diversity (1–6 ichnogenera), small size trace fossils (1–12 mm in diameter), and variable bioturbation intensity (0–6). The vertical variation in SDI values reflect changes in physico-chemical conditions during deposition of the Montney Formation, particularly across the Smithian-Spathian boundary. Understanding the lateral-facies variability and overall stratigraphic architecture of the Montney Formation in northeastern BC, constitute key elements in defining and correlating existing and new potential hydrocarbon reservoirs in the area.

Ordovician matground and mixground ecosystems in shoreface–offshore and barrier-island environments from Central Iran, northern Gondwana

AbstractThe shift of matground ecosystems to bioturbator-free settings was investigated in the Ordovician wave-dominated marine strata of the Shirgesht Formation in Central Iran. Ten ichnofabrics are recognized in shoreface–offshore and barrier-island sedimentary facies, representing a proximal-to-distal depositional trend along the studied profile. In the offshore settings, intensive burrowing on several tiers and bioirrigation, referred to theThalassinoides(Th),Cruziana–Skolithos–Rosselia(CrSkRo), crowdedTrichophycus(CT) andCruziana–Helminthopsis(CrHe) ichnofabrics, prevented the development of matgrounds. As a result of the Ordovician radiation, progressive ecospace utilization by suspension-, deposit- and detritus-feeders, as represented by theSkolithos(Sk),Rosselia–Skolithos(RoSk), crowdedRosselia(CR) andConichnus–Skolithos(CoSk) ichnofabrics, is regarded as a key factor for sediment mixing and reworking and thus disruption of the matgrounds in shoreface settings. However, the restriction on microbial growth was reduced in lower-offshore / shelf or tidal-flat and back-barrier settings, whereChondrites–Planolites(ChPl) andPlanolites(Pl) ichnofabrics dominate. This restricted microbial growth resulted from physico-chemical stresses on infaunal communities, as shown by the low ichnodiversity, scattered burrowing, absence of complex tiering, and prevalence of simple feeding strategies. This study suggests that following the early Palaeozoic evolutionary radiations, a considerable increase in abundance of detritus-feeders, deposit-feeders, suspension-feeders, predators, vagile bilaterian metazoans and grazers in shallow-water benthic communities caused mat-building microorganisms to migrate into lower-offshore / shelf, tidal-flat and back-barrier settings, where colonization by burrowing organisms was delayed.

Sedimentological and ichnological characteristics on macrotidal Baeksu tidal shoreface, southwestern coast of Korea

Integrated sedimentologic and ichnologic studies along the Baeksu coast of southwestern Korea have revealed that despite the macrotidal conditions, the morphologic characteristics and preserved deposits of the intertidal flats show strong similarities to those commonly reported from wave-dominated shorefaces. Morphologically, a beachface is developed near the high-tide level, which is backed by the high-tide mud flat and fronted by the extensive intertidal shoreface (sensu Dashtgard et al., 2021), where wave-formed swash bars are present. Although sedimentation is strongly influenced by seasonal winds and waves, the preserved deposits conspicuously comprise abundant storm beds that consist mainly of wave-rippled and hummocky cross-stratified sands, because summer muds are typically ephemeral. The storm beds, which are predominant and thick near the low-tide line, become thinner in a landward direction, due to the progressive dissipation of wave-energy by bottom friction. Such physical processes, exerted on tidal-shoreface sedimentation, are also reflected in the ichnofacies distribution, showing that distal expressions of the Skolithos Ichnofacies characterize the lower intertidal zone and are replaced landward by proximal expressions of the Cruziana Ichnofacies. Except for the low-BI beachface (BI 0–1), the intensities of bioturbation generally increase in a landward direction (BI 0–1 to BI 3–4), in correspondence with the physical-energy distribution.The study area reveals that the sedimentological and ichnological characteristics commonly employed to recognize wave-dominated shoreface settings (even including high-wave-energy tidal-shoreface counterparts) apparently show a reverse trend within the intertidal shoreface, probably overlying the normal-trend, subtidal shoreface. Although these findings have not been broadly tested, we, however, believe that these features are representative of the low-energy end of the full spectrum of wave-dominated coastal settings.

Late Cretaceous marine reptiles from Malyy Prolom in Ryazan Oblast, Central Russia

During the Cenomanian–Turonian transition (~94 Ma), what is today Central Russia formed part of the northern epicontinental margin of the Tethys Ocean. Diverse marine vertebrate faunas inhabited these palaeoenvironments, but their fossils are incompletely documented. Here, we report the discovery of marine reptile remains, recovered together with pterosaur, chondrichthyan, and actinopterygian fish material from a basal-most glauconitic sand and gravel layer of the Dmitrov Formation. These strata are exposed in an active quarry near the village of Malyy Prolom in the Shatsky District of Ryazan Oblast, Central Russia. The Dmitrov Formation deposits are middle–upper Santonian, but unconformably contact the underlying lower–middle Cenomanian Yakhroma Formation via a condensed boundary horizon that contains the vertebrate fossils with bivalve shell fragments and siliceous and phosphatic clasts. Such sedimentary characteristics indicate a high-energy shoreface setting where the vertebrate teeth and bones were likely reworked during cyclical regressions commencing in the latest Cenomanian–early Turonian. Time-averaging is also evidenced by the mixed occurrences of brachauchenine pliosaurids, elasmosaurid and polycotylid plesiosauroids, ophthalmosaurid ichthyosaurians similar to Pervushovisaurus, and a possible yaguarasaurine mosasauroid. These taxa are typical of Cenomanian–Turonian assemblages from across the northern peri-Tethys, and represent components of what were probably palaeobiogeographically widespread marine reptile faunas.

Crowded Rosselia ichnofabric in estuarine settings recording early transgressions in lowermost Permian post-glacial Gondwana (Rio Bonito Formation, Paraná Basin, S Brazil)

Ichnology has widely been used in paleoecological, paleoenvironmental, and evolutionary analysis. Rosselia is a dwelling burrow of infaunal, detritus-feeding terebellid polychaetes and is common in Phanerozoic shallow-marine deposits. The crowded Rosselia ichnofabric (CRI, i.e., a dense occurrence of Rosselia) provides itself in this study as a valuable guide to recognizing high-energy and high-frequency shoreface settings but is poorly recorded in estuarine settings. This study aims (1) to interpret the occurrence of Rosselia and the accompanying ichnofauna in the early Permian postglacial estuarine deposits of the Rio Bonito Formation (Paraná Basin) in southern Brazil and (2) to evaluate the potential of the CRI as an ichnomarker of transgressive events in estuarine settings. The study area presents a glacially incised paleovalley (the Capané paleovalley) near Caçapava do Sul town in the south of Brazil and exhibits 8 facies associations that tell the depositional history of the paleovalley-fill sediments. The succession indicates a confined and retrogradational stacking pattern and constitutes two high-frequency depositional sequences. The CRI is recurrent in three distinct intervals of Sequence 1; it occurs in both the sandy to clayey heterolithic facies and the sandstone facies. The CRI indicates relatively high-energy sedimentation that is likely associated with the storm events influencing the paleovalley during a marine transgression. The Rosselia specimens are either vertical or inclined to the bedding plane. The causative tubes vary from 5 to 10 mm in diameter and the spindle diameter ranges from 20 to 90 mm. Most of the specimens are preserved as funnel-shaped burrows; however, spindle-shaped burrows also occur. The density of burrows is high (60–80 per m2), representing a crowded Rosselia ichnofabric (CRI). The CRI reflects the high energy and the high frequency of the storm surges that impacted the Capané paleovalley estuary during the Early Permian. This scenario inhibited the presence of other tracemakers that colonized the surrounding subenvironments of the paleovalley, resulting in the preservation of a monotypic R. socialis assemblage in the storm-related deposits. These results provide new insights about the distribution of CRI in shallow marine environments and reinforce its value as a stratigraphic ichnomarker of high-energy, high-frequency storm deposits also in estuaries impacted by large-scale episodic marine incursions.

Ichnofauna from the Silurian–Devonian beds of the Parnaíba Basin at Poti River Canyon (Piauí State, NE Brazil)

This paper characterizes the ichnology and sedimentology of the Lower Paleozoic Parnaíba Basin beds exposed in the Poti River Canyon (Piauí State, NE Brazil) and discusses the paleoenvironmental significance of the ichnofauna. The sedimentary succession represents the Silurian–Devonian infill of the Parnaíba Basin and comprises mouth bar deposits (Ipu Formation) and shoreface deposits (Tianguá and Pimenteira formations). The Silurian ichnofauna is represented by Heimdallia isp. in the topmost beds of the Ipu Formation, and Musculopodus sedentarius, Didymaulichnus lyelli, Didymaulyponomos rowei, Diplocraterion isp., Heimdallia isp., Lockeia siliquaria, Nereites irregularis, Palaeophycus tubularis, and Thalassinoides cf. horizontalis in the Tianguá Formation. The Devonian ichnofauna occurs in the Pimenteira Formation and is represented by Beaconites antarcticus, Bifungites munizi, Bifungites crucifomis, Nereites isp., and Rhizocorallium commune. Horizontal burrows and furrows occupying shallow and middle tiers dominate the ichnofauna, suggesting proximal expressions of the Cruziana ichnofacies. The predominance of sandy, unbioturbated, storm-generated beds in the shoreface deposits indicates a high frequency of storm surges in shallower areas of the shelf, which often inhibited or frequently erased most of the post-event substrate colonization record. Thus, the trace fossil in the analyzed succession represents substrate colonization below the low-tide base and above the storm wave base in shoreface settings. The presence of Musculopodus sedentarius in this assemblage expands the geographic and temporal record of the ichnogenus. The similar composition of the trace fossil assemblage with other Lower Paleozoic ichnofaunas reinforces ichnostratigraphic correlations represented in coeval Gondwanan units.

Architecture of a tide-influenced, wave dominated shallow-marine deposit from a Paleoproterozoic rift setting: Example from the Badalgarh Formation, Bayana basin, Rajasthan, northwest India

A ~125 m thick shallowing-upward arenaceous succession from the Badalgarh Formation, Bayana basin, India provided the opportunity to document shelf to foreshore transition from a paleoproterozoic rift set-up. Process-based facies analysis allowed identification of 12 different shallow-marine facies types, grouped under four different facies associations namely (i) lower offshore or open shelf, (ii) upper offshore to distal lower shoreface, (iii) lower to middle shoreface and (iv) upper shoreface to foreshore. From unequivocal dominance of wave- and storm-generated features and fortuitous documentation of tide-generated structures in upper offshore, lower and middle shoreface settings, we infer a tide-influenced, wave-dominated coast at the Badalgarh Sea. From measurement of different vector attributes through the studied succession, we infer (i) near east–west orientation for the Badalgarh shoreline, (ii) storm deposits as products of shore-perpendicular return flow, and (iii) tidal peak flow at a high angle with the shoreline and confined in the upper offshore, lower and middle shoreface settings. A gradational transition from offshore to lower shoreface and, in turn, to middle and upper shoreface suggests accretionary character for the Badalgarh shoreface in a high-gradient rift setting. Overlying deep water (distal offshore) argillaceous marine strata, the arenaceous shallowing-upward Badalgarh succession is interpreted as a product of highstand systems tract (HST) constituted of stacked tens- to hundreds of meter-thick shallowing-upward depositional cycles. Since the abrupt shift in facies type (shallow to deep water) across the upper boundaries of depositional cycles is not unambiguous, we intend to assign these cycles as genetic stratigraphic cycles or T-R cycles over ‘parasequence’.

Trace fossils and depositional environments of the middle Turonian sandstones in the Upper Nysa Kłodzka Graben (Sudetes, Poland) revisited

We provide the first reports of some rare trace fossils from the middle Turonian (Upper Cretaceous) of the Sudety Mountains (SW Poland, Upper Nysa Kłodzka Graben, Długopole Górne Quarry). These include burrows ? Ancorichnus isp., Asterosoma cf. ludwigae Schlirf, 2000, Asterosoma isp., cf. Phycodes isp., Dactyloidites ottoi (Geinitz, 1849), Funalichnus strangulatus (Fritsch, 1883), Phycodes cf. palmatus Hall, 1852, cf. Phycodes , Phycosiphon incertum Fischer-Ooster, 1858, ? Phycosiphon isp., Planolites beverleyensis (Billings, 1862) and borings Entobia isp. Some body fossils, bivalves ? Brachidontes sp., Lima canalifera Goldfuss, 1836, Pinna ( Pinna ) cretacea (Schlotheim, 1813) and Rhynchostreon suborbiculatum (Lamarck, 1801) are also reported. The trace fossil assemblage indicates a distal Skolithos ichnofacies and proximal Cruziana ichnofacies, which characterize a proximal and distal lower shoreface setting respectively. Sedimentation of the middle Turonian sandstones took place in a shallow epicontinental sea of normal salinity and a soft substrate, which was well-oxygenated under low-moderate hydrodynamic conditions. The presence of the oyster Rhynchostreon in the deposits studied suggests the influence of a warm Tethys Ocean.

High-Resolution Seismic Stratigraphy Offshore Haeundae Beach in Busan, South Korea

Choi, D.-L.; Shin, D.-H.; Jin, J.-Y.; Lee. Y.-K., and Kum, B.-C., 2020. High-resolution seismic stratigraphy offshore Haeundae beach in Busan, South Korea. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Geospatial Research of Coastal Environments. Journal of Coastal Research, Special Issue No. 102, pp. 187-193. Coconut Creek (Florida), ISSN 0749-0208.The stratigraphic architecture of the Haeundae shallow sea was evaluated using numerous high-resolution single-channel seismic profiles and drilled cores. Two major seismic units over the basement, the lower Unit II and upper Unit I, as well as two subunits (Units Ia and Ib) in the upper Unit I were identified in the study area. Unit II shows numerous chaotic diffraction hyperbolic seismic reflection patterns overlying high amplitude, and irregular reflection of the bedrock surface, corresponding well with the gravel-dominated deposits. Unit II is interpreted as nonmarine alluvial deposits in the Quaternary glaciations. Unit I is present over Unit II with two distinct subunits at different locations: Unit Ia, distributed inshore within ∼10 m depth, and Unit Ib, offshore beyond ∼13 m depth. Unit Ia, which is accumulated more in the western inshore section, exhibits an acoustically semi-transparent and sigmoidal clinoform wedge and is well correlated with sand-dominated deposits from core data. Unit Ib, which pinches out landward but gradually thickens seaward, is generally characterized by transparent seismic facies, likely made up of very fine sandy to muddy sediments from surface sediments. The depositional environments of Units Ia and Ib are categorized as shoreface settings and the landward innermost part of the Nakdong distal delta system during late Holocene sea-level highstand, respectively. Due to severe weather conditions associated with winter storms and summer typhoons as well as human interventions, the sediment morphology and its distribution are thought to have constantly been reactivated and modified.