Intertidal Deposits Research Articles

Tidal-influenced shoreline interpretation of Miocene Tanjong Formation in Imbak Canyon, Sabah, Malaysia

The Tanjong Formation of Imbak Canyon, Sabah is the Early Miocene aged shallow marine unit that crops out in the Tongod district. Tanjong Formation has previously been interpreted to have been deposited in a shallow marine environment without tidal influence. This paper reinterpreted the depositional environment with emphasis on tidal deposits through newly logged sections encountered during 2019 Imbak Canyon Expedition. Proximity-driven strike orientation correlations were employed to interrelate the logged geological sections. The eight facies recognized are 1) Mudstone Facies (M), 2) Lenticular Facies (LF), 3) Wavy Facies (WF), 4) Flaser Facies (FF), 5) Hummocky Cross-Bedded Sandstone Facies (HCS), 6) Swaley Cross-Bedded Sandstone Facies (SCS), 7) Planar Cross-Bedded Sandstone Facies (PCS), and 8) Structureless Sandstone Facies (SS). Three interpreted facies associations deduced are 1) intertidal deposits, 2) middle to lower shoreface, and 3) offshore deposits. We conclude that Tanjong Formation was deposited in a macrotidal open coast setting with significant tidal imprint signatures. The identification of tidal influence within a wave-dominated system is an infrequent occurrence, yet it holds significant potential for enhancing the refinement of shallow marine models.

Decoding the Interplay Between Tidal Notch Geometry and Sea‐Level Variability During the Last Interglacial (Marine Isotope Stage 5e) High Stand

AbstractRelic coastal landforms (fossil corals, cemented intertidal deposits, or erosive features carved onto rock coasts) serve as sea‐level index points (SLIPs), that are widely used to reconstruct past sea‐level changes. Traditional SLIP‐based sea‐level reconstructions face challenges in capturing continuous sea‐level variability and dating erosional SLIPs, such as tidal notches. Here, we propose a novel approach to such challenges. We use a numerical model of cliff erosion embedded within a Monte Carlo simulation to investigate the most likely sea‐level scenarios responsible for shaping one of the best‐preserved tidal notches of Last Interglacial age in Sardinia, Italy. Results align with Glacial Isostatic Adjustment model predictions, indicating that synchronized or out‐of‐sync ice‐volume shifts in Antarctic and Greenland ice sheets can reproduce the notch morphology, with sea level confidently peaking at 6 m and only under a higher than present erosion regime. This new approach yields insight into sea‐level trends during the Last Interglacial.

Subtidal to intertidal deposits in a mixed clastic–carbonate epicontinental seaway, the Windy Hill Sandstone and Upper Sundance Formation (Oxfordian), Wyoming, U.S.A.

Abstract Oxfordian deposits in northern Colorado and Wyoming, USA, preserve proximal, intertidal, clastic, coastal deposits and distal, offshore to nearshore, subtidal bioclastic facies that accumulated during a forced regression of the Jurassic epeiric sea. This contrasts with the common association between tidal deposits, carbonate facies, and rising sea level common to many depositional models of mixed clastic–carbonate systems. Ichnology, sedimentology, and architecture of these deposits were documented along a 460 km outcrop transect to test previous depositional interpretations and decipher the mechanisms driving the change from proximal, siliciclastic, intertidal flats to distal, bioclastic, subtidal macroforms. In southeastern Wyoming, the Windy Hill Sandstone (WH) is composed of very fine, SiO2-dominated, intertidal facies that truncate offshore to lower shoreface, storm-dominated deposits of the Redwater Shale Member (RS) of the Sundance Fm. Eolian and small fluvial systems delivered sand to the coastline after subaerial erosion reworked it from older, uplifted Jurassic strata onshore. The regional and time-transgressive J-5 unconformity separating the WH from the RS is readily identifiable using ichnological and sedimentological criteria. In the Wind River and Bighorn basins to the north, the Upper Sundance Fm (USF) is time-equivalent to the WH but is composed of glauconitic, silt-prone sandstone and meter- to decimeter-scale, bioclastic, cross-bedded sandstone bodies. The abundance of molluscan shell material and limited volume of siliciclastic sediment in the geographically widespread outcrops suggests that nearby, marine shoals were the source of the coarse-grained material. Bioclastic, cross-stratified sandstone bodies represent two architectural elements: 1) coarsening-upward bodies with seaward-dipping foresets arranged into complexes bounded by seaward-directed bounding surfaces interpreted to represent subtidal compound dunes and 2) landward- and laterally accreting tidal-inlet fills composed of meter-scale, landward-accreting bodies with some landward-directed current ripples. The presence of transgressive tidal inlets supports previous interpretations that the WH and USF record high-frequency transgressions superimposed on a tectonically driven forced regression.

From apex to shoreline: fluvio-deltaic architecture for the Holocene Rhine–Meuse delta, the Netherlands

Abstract. Despite extensive research on alluvial architecture, there is still a pressing need for data from modern fluvio-deltaic environments. Previous research in the fluvial-dominated proximal and central Rhine–Meuse delta (the Netherlands) has yielded clear spatial trends in alluvial architecture. In this paper, we include the backwater length to establish architectural trends from apex to shoreline. Channel-belt sand body width / thickness ratios and interconnectedness were determined, and the proportions of fluvial channel-belt deposits, fluvial overbank deposits, organics and intertidal deposits were calculated for the complete fluvio-deltaic wedge based on high-resolution geological cross sections. It was found that the average width / thickness ratio of channel-belt sand bodies in the proximal delta is 5 times higher than in the distal delta. Other down-valley trends include an 80 % decrease in the channel deposit proportion (CDP) and a near-constant proportion of overbank deposits. Additionally, interconnectedness in the proximal delta is 3 times higher than in the distal delta. Based on the Rhine–Meuse dataset, we propose a linear empirical function to model the spatial variability of CDP. It is argued that this relationship is driven by four key factors: channel lateral-migration rate, channel-belt longevity, creation of accommodation space and inherited floodplain width. Additionally, it is established that the sensitivity of CDP to changes in the ratio between channel-belt sand body width and floodplain width (normalized channel-belt sand body width) varies spatially and is greatest in the central and distal delta. Furthermore, the proportion of fluvial channel-belt sands is generally an appropriate proxy for the total sand content of fluvio-deltaic successions, although its suitability as a total sand indicator rapidly fades in the distal delta. Characteristics of the backwater zone of the Rhine–Meuse delta are (1) sand body width / thickness ratios that are lower as a consequence of channel narrowing (not deepening), (2) a rapid increase and then a drop in the organic proportion, (3) an increase in the total sand proportion towards the shoreline, and (4) a drop in the connectedness ratio. For this paper, unique high-resolution quantitative data and spatial trends of the alluvial architecture are presented for an entire delta, providing data that can be used to further improve existing fluvial stratigraphy models.

Lithostratigraphy, microfacies and paleogeography of the shallow marine Middle Limestone Member of the Early Eocene Rusayl Formation, Oman: Relationship to the Early Eocene Climatic Optimum, sea-level changes and regional uplift

We logged five outcrops of the Middle Limestone Member (MLM) of the Early Eocene Rusayl Formation. The eastern sections contain more, much coarser and also more angular detritus than the western sections. Moreover, notable concentrations of red algae, gastropods, corals, oysters and echinoids only occur in the eastern sections. Benthic foraminifers are typical for the entire MLM, but in the west, they are more abundant (dominated by miliolids). Peloids are restricted to the western sections. While the western sections display a subtidal lagoonal facies, capped by thin intertidal deposits, the coarse clastic material of the eastern sections indicates the proximity of a mountainous paleocoast with a resulting rocky coast environment. The coarse eastern facies proves that the Saih Hatat Dome as part of the Oman Mountains had already emerged while the MLM accumulated. Because of the differences, no outcrop correlations between the western and eastern sections are possible. However, facies boundary correlations among the western sections are feasible, spanning a distance of 23.5 km. Among the eastern sections, basal coarse clastics as well as two bioclastic marker horizons were correlated over 26 km. Deposition of the MLM was favored by high temperatures during the Early Eocene Climatic Optimum (EECO) at 53-51 Ma and a correspondingly high eustatic sea-level. The presence of corals in proximity of a mountainous, rocky paleocoast indicates dry conditions (clear water) during the EECO. The final shallowing-up observed in the west is attributed to the end of the EECO when mean global temperatures and the eustatic sea-level dropped. Shallowing from subtidal to intertidal conditions restricted parts of the lagoon and caused evaporation/hypersaline conditions as indicated by monospecific small miliolids and also by early dolomitization due to Mg-rich brines (reflux model). The western sections show signs of dolomitization. The Al-Khod section is the first one to be reported to be intensely dolomitized.

Natural and anthropogenic organic matter inputs to intertidal deposits of the urbanized Arctic region: A multi-proxy approach

Growing anthropogenic activity in the Arctic, especially near regional municipal and transportation hubs, threatens coastal environments with significant changes and contamination. A detailed study of a wide set of organic-geochemical proxies in surface and subsurface sediments and soils around the typical urbanized Arctic area (Tromsø, Norway) was performed to investigate natural and anthropogenic input of hydrocarbons. The sites were located close to main areas of human activity and differed in the level of anthropogenic pressure: oil terminal, boat harbor and recreation beach zone in the city center, and a remote, conditionally-clean area. The samples from each site were collected along four subtidal – intertidal – supratidal transects. GC–MS data on the distribution of more than 110 compounds were obtained including n-alkanes, isoprenoids, terpanes, parent polycyclic aromatic hydrocarbons (PAHs), and alkyl PAHs. Organic matter embedded in a mineral matrix was more thermally mature than its fresh non-bound fraction. Biomarker distribution and diagnostic ratios attested to the predominantly local origin of near-shore organic matter formation (phytoplankton, algae, high foliar plants, grass). PAH composition revealed a significant input of pyrogenic components from liquid and solid fuel combustion to the surface coarse-grained sediments. Background bacterial activity was evidenced by the high content of biohopanes and hopenes in less polluted sediments and soils. The presence of an unresolved complex mixture and even n-alkanes in sediment profiles from the most polluted sites attested to the active biodegradation that, together with the erosion of the upper layers by tidal currents, reduces the toxic compound penetration deeper into the sediments.

Causes and implications of Mid- to Late Holocene relative sea-level change in the Gulf of Kachchh, western India

AbstractThe relict intertidal deposits from the Kharod River Estuary, Gulf of Kachchh, and the distal end of Kori Creek are used to infer the Mid- to Late Holocene relative sea-level (RSL) change in western India. Employing sedimentology, geochemistry, palynology, ichnology, and optical and radiocarbon dating, the study suggests the dominance of fluvial activity between 16.5 ± 1.6 and 9.9 ± 0.7 ka. After ~7 ka (7.3 ± 0.4, 6.8 ± 0.5 ka), the sea level showed a positive tendency until 4.7 ± 0.2 ka. The tectonically corrected Mid-Holocene RSL change is estimated as 1.45 ± 0.33 m between ~7 and ~5 ka. The study suggests that the Mid-Holocene RSL high was due to the meltwater contribution from the Himalayan cryosphere, with subordinate contribution from glacio-isostatic adjustment and crustal subsidence. The Late Holocene tectonically corrected RSL change at ~1 ka (1.1 ± 0.1 ka and 1045 ± 175 cal yr BP) is estimated as 0.53 ± 0.43 m. This is ascribed to monsoon wind-driven tidal ingression that might have affected the tidal amplitude positively. The study suggests that the Mid-Holocene RSL change did not play a deterministic role in the abandonment of the Harappan coastal settlements.

Sedimentary Environment Division by Clayey Water Electrical Conductivity and Grain-Size Analysis: A Case Study of an xz-Borehole in the Western Plain of Bohai Bay, China

Fang, J.; Zhang, L.; Liu, Y.; Chen, G.; Yang, S.; Wang, T., and Wang, F., 2020. Sedimentary environment division by clayey water electrical conductivity and grain-size analysis: A case study of an xz-borehole in the western plain of Bohai Bay, China. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 99–103. Coconut Creek (Florida), ISSN 0749-0208.According to the measured value of clayey water electrical conductivity (EC) of xz-borehole core samples from the south bank plain of the Haihe River in Tianjin, the marine and continental strata of the xz-borehole core were divided. From bottom to top, the core represents the regression process of a neritic facies deposit (Zone I), intertidal deposit (Zone II), and continental deposit (Zone III). The hydrodynamic conditions of xz-borehole marine facies, sea–land transitional facies, and terrestrial strata were analyzed by grain-size analysis methods such as probability accumulation curve and CM diagram, and the sedimentary facies were further divided according to sediment grain size and sorting characteristics. Zone I is subdivided into a neritic facies deposit with a finer grain size and hydrodynamic stability (I-1 and I-3), a neritic facies deposit with a coarser grain size and stronger hydrodynamic force (I-2), and a delta front deposit with rapid EC value decline and a coarse grain size (I-4). Zone III, with a low EC value, is subdivided into fine-grained floodplain–flooding plain sediments (III-2) and coarse-grained crevasse splay sediments (III-1). High-energy hydrodynamic events in the deposition process can be accurately identified with grain-size analysis and EC indicators. Therefore, it can make up for the defect that EC cannot further refine the internal sedimentary facies for the marine facies, transitional facies, and continental facies. It has a good effect on the detailed differentiation of sediments and sedimentary facies in the coastal plain, and the identification of sedimentary events.

Heterolithic Lower Rewa Sandstone of the Neoproterozoic Rewa Group, Vindhyan Basin, U. P., India: An example of tidal point bar

The Lower Rewa Sandstone of the Rewa Group exposed in Drummondganj ghat area is about 15 m thick; it shows well developed features of tidal and wave origin. The sandstone succession characterized by Inclined Heterolithic Strata (IHS) is composed of three lithofacies associations namely, i) Sandstone lithofacies association (A), ii) Siltstone lithofacies association (B) and iii) Shale lithofacies association (C). These three lithofacies associations are repetitive and signify vertically stacked parasequences, which are further divisible into smaller hemicycles showing fining upward in terms of grains size and lithology. The studied section is characterized by heterolithic facies, lateral accretion elements (LA surfaces) with tide generated features such as cross-beddings with mudstone drapes, lenticular and wavy bedding, often of wave origin, suggesting a tidal point bar of a sinuous estuarine channel formed along coast line having momentous tidal action, superimposed by significant wave action. The upper part of the section, characterized by erosionally based cross-bedded sand-bodies with occasional mudstone drapes and current modified wave ripples, indicates translation of river-dominated inner part of an estuarine channel over the mixed-energy zone of the estuary in the sense of Dalrymple et al. (1992). The complete Lower Rewa Sandstone represents a 3rd order Highstand Systems Tract (HST). Palaeocurrent pattern is polymodal suggesting subtidal to intertidal sedimentation whereby sediment was moved mainly by tidal action with intermittent wave activity. Petrographic study reveals that the fine to very-fine grained sandstone is quartzarenite, which has been derived from a stable cratonic uplifted basement.

Intense deposition and rapid processing of seafloor phytodetritus in a glaciomarine fjord, Andvord Bay (Antarctica)

The West Antarctic Peninsula (WAP) region encompasses numerous fjords known to be hotspots of benthic biodiversity and biomass. These ecosystems are undergoing rapid climate warming and oceanographic change; consequent glacial melt and retreat may dramatically alter benthic communities and ecosystem functions in WAP fjords. In addition, there is extreme variability in seasonal productivity and phytodetrital food input to the deep shelf benthos of the WAP. Here we document the flux and utilization of phytodetritus at 530 m depth in Andvord Bay, a WAP glaciomarine fjord, using seafloor time-lapse images spanning a 10-month period, from December 2015 to September 2016. To explore the relationship between sea-surface conditions and detrital export, we developed a color-based method to quantify seafloor phytodetritus cover in time-lapse images, and correlated phytodetritus cover with sea-ice cover and surface wind speed. During the most rapid period of phytodetritus accumulation in early January 2016, approximately 3 cm of phytodetritus was deposited on the fjord floor over six days, representing a large input of organic carbon to the benthos. The timing of this rapid export event was not related to overlying wind conditions and occurred when the fjord was ice-free. To assess the response of the megafaunal community, we measured fecal-pellet production by the dominant surface deposit-feeder, the ampharetid polychaete Amythas membranifera. The deposit-feeding rate of A. membranifera increased substantially during high seafloor phytodetritus cover and returned to background levels for the rest of the autumn and winter. Ampharetids and mobile megafauna were observed to feed throughout the entire time-series, including beneath winter sea ice, suggesting that the delivery of phytodetritus from surface phytoplankton blooms in spring/summer sustains these abundant populations year-round with a sediment food bank. A. membranifera can reach densities of >37 m−2 and, as a population, processes a volume equivalent to the top 1.05 cm of sediment annually. The maximum individual feeding rates measured are comparable to some temperate intertidal deposit feeders. Nonetheless, phytodetritus on 31–73% of the seafloor was consumed by macrofauna or microbial populations not visible in time-lapse photographs, suggesting that recently deposited phytodetritus is processed primarily by these smaller size classes. This study demonstrates the seasonal coupling and subsequent decoupling of detritivore activity in response to a massive detrital deposition event in a deep, subpolar WAP fjord. This work indicates that both megafaunal deposit feeders and smaller size classes play important roles in processing labile organic matter in WAP fjord ecosystems.

On small quadrupedal ornithopod tracks in Jurassic-Cretaceous transition intertidal deposits (El Castellar, Teruel, Spain)

The study of an undescribed part of the El Pozo tracksite in El Castellar (Teruel, Spain) has revealed two new trackways made by small ornithopods showing new evidences of basal ornithopods pes and manus track morphologies in the Jurassic-Cretaceous transition. The site lies within the Villar del Arzobispo Formation, which was deposited during the Tithonian-Berriasian in an environment under the influence of tides. The pes tracks are small tridactyl tracks, the digits are similar in size, and the heel is open and rounded. The presence of oval manus tracks in front of the tridactyl tracks is one of the trackways confirms that the dinosaur is a representative of the dryosaurid or the basal Ankylopollexia clades. These tracks are smaller than those described for the Las Cerradicas site, also located in Teruel and in the same formation; consequently, these tracks from El Pozo site constitute some of the smallest ornithopods trackways with quadrupedal locomotion ever described in the world. In addition, in the same tracksite bed, there are some poorly preserved tracks attributed to big quadrupedal dinosaur

Filter feeding in Late Jurassic pterosaurs supported by coprolite contents.

Diets of pterosaurs have mainly been inferred from indirect evidence such as comparative anatomy, associations of co-occurring fossils, and functional morphology. Gut contents are rare, and until now there is only a single coprolite (fossil dropping), with unidentified inclusions, known. Here we describe three coprolites collected from a palaeosurface with numerous pterosaur tracks found in early Kimmeridgian (Hypselocyclum Zone) intertidal deposits of the Wierzbica Quarry, Poland. The specimens’ morphology and association to the tracks suggest a pterosaur producer. Synchrotron scans reveal numerous small inclusions, with foraminifera making up the majority of the identifiable ones. Other small remains include shells/carapaces (of bivalves, ostracods, and other crustaceans/arthropods) and bristles (some possibly of polychaete worms). The high density of the small shelly inclusions suggest that they were not accidently ingested, but constituted an important food source for the pterosaur(s), perhaps together with unpreserved soft-bodied animals. The combined evidence from the tracks and coprolites suggest a filter-feeding ctenochasmatid as the most likely tracemaker. If true, this significantly expands the bromalite record for this pterosaur group, which was previously only known from gastroliths. Moreover, this study also provides the first direct evidence of filter feeding in Jurassic pterosaurs and shows that they had a similar diet to the recent Chilean flamingo (Phoenicopterus chilensis).

Combined analysis of sulfur and carbon contents, and foraminifer as paleoenvironmental indicators in tidal flat sediments on Miura Peninsula, Japan

Reconstruction of natural hazards from tidal flat sediments is essential for assessment of coastal hazards, and is based on knowledge of recent sediments. This study therefore examined recent sediments deposited on a narrow, muddy tidal flat on Miura Peninsula, metropolitan Tokyo, Japan, by means of sedimentological analysis, C, N, and S elemental analysis, carbonate content, 137Cs dating, and analysis of benthic foraminifera (species composition and degree of preservation). 137Cs profiles of four sediment cores of ∼20 cm in length showed that the sediments were deposited after the release of 137Cs by the accident at the Fukushima No. 1 Nuclear Power caused by the Tohoku-oki tsunami at March 2011. Results of C/S ratios of mud fractions indicated that the intertidal deposits in the central bay are characterized by low C/S ratios (4.9–11.4) and the bayhead deposits of the upper intertidal and supratidal zones by higher ratios (13.9–24.9). A fluid–mud layer identified in the central bay had the same C/S ratios and carbonate contents as marine sediments, indicating that the fluid-mud deposits probably resulted from resuspension of mud caused by storm-wave action after March 2011. Faunal analysis of benthic foraminifera showed that very low density of foraminifera can be regarded as one of the defining characteristics of fluid-mud deposits.

Pterosaur track assemblages from the Upper Jurassic (lower Kimmeridgian) intertidal deposits of Poland: Linking ichnites to potential trackmakers

Two distinct tetrapod track assemblages, dominated by pterosaur traces, are reported from Upper Jurassic (lower Kimmeridgian, Hypselocyclum Zone) tidal flat carbonate deposits exposed in Wierzbica Quarry, 20 km south of Radom, Poland. The pterosaur tracks, tentatively assigned to Pteraichnus isp. are well preserved as a positive hyporelief in intertidal facies. Some are preserved with anatomical details (e.g., skin, claw or digital pad impressions) and quality sufficient to make preliminary ichnotaxonomic assignment. Nearly all collected specimens are larger than most other pterosaurian ichnites of the Late Jurassic age, thus adding to the growing diversity of pterosaur traces known from this time period. Morphometrical and anatomical analyses show that ctenochasmatoids or possibly non-pterydactyloid monofenestratans or rhamphorhynchids were most likely the trackmakers. Anatomical comparisons give new insights into the morphology of the pes of pterydactyloids and the most closely related non-pterodactyloids which may be correlated with a niche expansion into marginal marine and lacustrine environments by Middle and Late Jurassic pterosaurs. The palaeoenvironmental interpretation as tidal flat is confirmed by presence of vertically accreted tidal bundles, each representing deposition in one tidal cycle. Most likely then, this was one of the environments frequented by these pterosaurs and other small tetrapods. The wider palaeoecological significance of the tracks is evaluated in the context of other similar reports from the Late Jurassic of Europe, Africa and North America.

Facies evolution of the Jurassic-Cretaceous transition in the Eastern Getic Carbonate Platform, Romania: Integration of sequence stratigraphy, biostratigraphy and isotope stratigraphy

Piatra Craiului Massif is situated in the easternmost part of the Southern Carpathians, Romania. The Kimmeridgian–lowermost Valanginian carbonate succession from this area is part of the large Getic Carbonate Platform system, and forms a 25 km long, NE-SW oriented calcareous ridge with a maximum thickness of 1200 m. Previous studies of Upper Jurassic-Lower Cretaceous carbonate platforms from Romania focused on microfacies and biostratigraphic features but few studies addressed their sequence stratigraphy. This study aims to decipher the geological evolution of the Eastern Getic Carbonate Platform by integrating sequence stratigraphic, biostratigraphic and chemostratigraphic analysis methods. The studied sections are located in the northern and central part of the Piatra Craiului Massif. Centimeter to meter thick carbonate beds or banks are common and carbonate lithologies reveal five facies associations (F1F5) of outer platform deposits and inner platform peritidal settings. The outer platform deposits contain fragments of subaerially exposed intraclasts. Such processes are indicated by the facies characteristics and isotope chemostratigraphy data. The peritidal succession is characterized by the repetition of distinct sets of small-scale sequences, each of which commonly shows a deepening to shallowing upward trend. This trend is defined by a vertical scale transition from high-energy intertidal deposits to intertidal restricted ponds, swamps or supratidal marshes. The general trend shows a shallowing upward tendency. Commonly, intertidal deposits cap the shallowest facies of the corresponding small-scale sequences. The entire peritidal succession from the Piatra Craiului Massif forms a superimposed prograding wedge on platform margin deposits. Autocyclic processes and allocyclic processes appear to be responsible for the development of this carbonate succession.

Factors affecting the spatial and temporal distribution of E. coli in intertidal estuarine sediments

Microbiological water quality monitoring of bathing waters does not account for faecal indicator organisms in sediments. Intertidal deposits are a significant reservoir of FIOs and this indicates there is a substantial risk to bathers through direct contact with the sediment, or through the resuspension of bacteria to the water column. Recent modelling efforts include sediment as a secondary source of contamination, however, little is known about the driving factors behind spatial and temporal variation in FIO abundance. E. coli abundance, in conjunction with a wide range of measured variables, was used to construct models to explain E. coli abundance in intertidal sediments in two Scottish estuaries. E. coli concentrations up to 6 log10 CFU 100 g dry wt−1 were observed, with optimal models accounting for E. coli variation up to an adjusted R2 of 0.66. Introducing more complex models resulted in overfitting of models, detrimentally affected the transferability of models between datasets. Salinity was the most important single variable, with season, pH, colloidal carbohydrates, organic content, bulk density and maximum air temperature also featuring in optimal models. Transfer of models, using only lower cost variables, between systems explained an average deviance of 42%. This study demonstrates the potential for cost-effective sediment characteristic monitoring to contribute to FIO fate and transport modelling and consequently the risk assessment of bathing water safety.

A mid-late Holocene tidally-influenced drainage system revealed by integrated remote sensing, sedimentological and stratigraphic data

Despite the growing employment of Remote Sensing (RS) techniques in paleoenvironmental studies, the stratigraphic interpretation of RS-derived paleodrainage traces is still an open issue, as their relation to subsurface is largely unexplored. Here we applied a multi-data analysis approach, including publicly available optical images from different satellites (Landsat, ASTER, Sentinel, Hyperion), LiDAR-derived Digital Terrain Model (DTM), soil reflectance spectra and facies core data, which succeeded in revealing a paleodrainage system buried beneath a 200-sq km wide wetland (the Mezzano Lowland-ML) of the Po coastal plain (northern Adriatic Sea, Italy). Data integration in a GIS environment allowed the 3D mapping of numerous and temporally persistent meandering traces. From distal to proximal locations, the RS-derived traces show a hierarchical organization, in terms of sinuosity and width, and form a dense and dendritic pattern typical of a tidally-influenced system. Surface and subsurface cross-investigation of two meandering traces through soil reflectance spectra and core stratigraphy reveal that these landforms represent the surface expression of buried channels that eroded the underlying lagoonal succession, with lateral transition to intertidal deposits. LiDAR-detected micro-morphologies related to paleomeanders evolution strongly influenced the spatial distribution of mid-late Holocene peat-bearing lithofacies (i.e., salt marsh and swamp), and hence soil moisture distribution, inducing the sharp radiance contrasts (traces) detected by satellite sensors on the surface. On-trace areas invariably lack peat deposits and record the top of 3–4 m-thick channel-fill sands, some 2–4 m below the ground level. In contrast, out-of-trace areas are characterized by organic-rich soils that cap a 2.5–3.5 m-thick succession of intertidal-supratidal peat deposits, accumulated in depressed areas lateral to the channel-levee complex. We conclude that in the early stage of Po Delta construction, between ca. 6000–2500 cal yr BP, two distinct tidal-influenced drainage networks fed the Mezzano Lowland lagoon under a predominantly autogenic control. These findings indicate the suitability of a low-cost RS-stratigraphic approach to improve the reconstruction of past paleogeographic scenarios buried beneath deltaic lowlands, shedding new light on the evolution trends of coastal landforms, environments and sedimentary patterns under highstand conditions.

Geologic and resource assessment of the Upper Devonian Grosmont and upper Ireton Formations, central Grosmont shelf complex, Alberta, Canada

The Devonian Grosmont and upper Ireton (GUI) Formations of northeastern Alberta contain between 300 and 574 billion bbl of in situ bitumen. The GUI stratal succession shallows upward and is partitioned into five progradational, shallow marine sequences. Although matrix porosity is highest within intertidal deposits (commonly 20%–30%), matrix permeability is similar for subtidal and intertidal facies (commonly 10–3000 md). Reservoir zones are 29–98 ft (9–30 m) thick and from oldest to youngest include the A1, A2, B, C1, C2, D1, D2, D3, and upper Ireton. Because of truncation beneath the sub-Cretaceous unconformity, the GUI thins from 656 ft (200 m) within the western part of the study area to an erosional edge within the easternmost part. Intertidal facies most commonly underlie the sub-Cretaceous unconformity and are commonly karsted. Karst breccia and associated fractures occur within thin (3–20 ft [1–6 m]) intervals that are parallel to bedding and most abundant in proximity (164–328 ft [50–100 m]) to the unconformity. Within the study area bitumen is concentrated above 475 ft (145 m) above sea level, and in-place bitumen is estimated at 58 billion bbl (9.2 × 106 m3); the greatest in-place bitumen volume (66%) is associated with the D2, D3, and upper Ireton intervals. A proof-of-concept numerical model evaluates the potential effectiveness of steam-assisted gravity drainage enhanced oil recovery within the GUI. The model suggests bitumen recovery as high as 189,000 bbl over a 20-yr period with an injector–producer spacing between 33 and 41 ft (10 and 12 m).

Middle Devonian parathuramminid and earlandiid foraminifers from shallow marine carbonates of the Carnic Alps (Austria)

AbstractThe Devonian of the Carnic Alps (Austria) is developed in different facies. The shallow marine facies is up to 1200 m thick. The Feldkogel Limestone of the Polinik Formation, >330 m thick, was dated as Eifelian–Late Devonian. The Feldkogel Limestone at Mount Polinik is developed in a peritidal facies composed of subtidal, intertidal, and supratidal deposits. Subtidal sediments are represented by dark grayAmphiporalimestone and intertidal deposits by laminated and partly bioturbated grainstone and packstone, ostracode wackestone to packstone, and locally intercalated intraclast breccias documenting tidal channel fills. Laminated microbial mats (stromatolites) formed in a supratidal depositional environment. Grainstone and packstone contain abundant unilocular parathuramminid foraminifers. This latter group encompasses a diversified assemblage of ivanovellids, parathuramminids, uralinellids, and irregularinoids; some earlandiids are also present. They are dated herein as late Eifelian–early Givetian. These foraminifers provide a more precise systematics of these taxa, which often have not been studied for more than half a century. The taxonomic problems of their assignment to foraminifers, pseudo-foraminifers, calcitarcha, thaumatoporellaceans, volvocaleans, or other algae are also discussed. Several taxa are emendated: Parathuramminida, Parathuramminoidea, Irregularinoidea, Eovolutinidae, Ivanovellidae, Parathuramminidae, Uralinellidae,Ivanovella,Elenella,Neoarchaesphaera,Parathurammina,Bykovaella,Uralinella, andParacaligella. The new taxa are:Ivanovella reitlingeraen. sp.,Elenella polinikensisn. sp.,Uralinella sabirovin. sp., andRadiosphaerella poyarkovin. sp.

Subsidence along the central to southern Sanriku coast, northeast Japan, near the source region of the 2011 Tohoku-oki earthquake, estimated from the Holocene sedimentary succession along a ria coast

Along the Sanriku coast, northeast Japan, discrepancies in crustal movement have been reported between uplift on a scale of 105 years versus subsidence on a scale of 101–102 years. Well-dated Holocene incised-valley-fill sediments provide records of millennial-scale vertical crustal movement, which is key to understanding the tectonic history in this area. Previous studies of the age and distribution of early Holocene intertidal deposits in incised valleys reported that the southern Sanriku coast has subsided during the Holocene at an average rate of about 1 mm/yr. Here we studied three sediment cores, TGI1, TGI2, and TGI3, collected from the Tsugaruishi plain on the central Sanriku coast, and recognized a Holocene deltaic sediment succession in all three cores. In core TGI3, from the farthest inland site, the intertidal sediment facies, deposited from 7500 to 7000 cal BP, and the overlying 6-m-thick floodplain facies, deposited from 7000 to 5000 cal BP, are both below the present sea level. Because a sea-level highstand due to hydroisostatic uplift around Japan occurred in the mid-Holocene, we inferred that the Tsugaruishi plain subsided during the Holocene, and the estimated subsidence rate, 1.1–1.9 mm/yr at maximum, is consistent with the recently reported subsidence rate along the southern Sanriku coast. The results of this study confirm that the central to southern Sanriku coast is subsiding, in contrast to an interpretation based on the study of marine terraces that this part of the coast is uplifting. The empirical data presented here will be useful for constructing an earthquake cycle model related to plate subduction.