Sedimentologika
type: channel
description: Sedimentologika is a community-driven, free to publish, free to access, and free to share scientific journal about sedimentology, stratigraphy, and related fields.
publisher: Bibliothèque de l'Université de Genève
language: en
publication name: Sedimentologika
issn: 2813-415X
items: Mazon Creek-type Lagerstätten in Pennsylvanian Coal Basins of the US Midcontinent: Biotic Associations and Depositional Frameworks
items: Seismic, tomographic and oceanographic insights into water mass interactions and sediment stability on the Demerara Plateau
items: Straits: stargates for the future
items: Integrating field-based and digital datasets to improve geometric accuracy of geologic cross sections constructed from outcrop
items: Transition from wave- to tide-dominated estuary: An example from the Eocene Urahoro Group, eastern Hokkaido, northern Japan
items: A lee-side cavity fill diamicton under the Durance valley glacier: Insights from hoodoos of the Remollon Arch, Southern French Alps
items: Evolution of a Tethyan carbonate platform through the Jurassic tectonic and climatic upheavals
items: Diagenetic evolution and reservoir quality of Aptian lacustrine reworked carbonates from the Santos Basin, Brazilian pre-salt
items: Beyond single-cause models: Investigating variable pathways to submarine fan architectures in the Golo Fan system
items: Depositional model for the spatiotemporal evolution of a mixed carbonate-siliciclastic icehouse system: Pennsylvanian Strawn Group, Eastern Shelf, Permian Basin, USA
items: New insights on the depositional environment and dynamics of the lowermost Triassic in Svalbard: linking the Sørkapp-Hornsund High to western and central Spitsbergen
items: Settling velocity of sediment grains, Part 1: Natural sediment particles are not ellipsoids
items: Settling velocity of sediment grains, Part 2: Volume/area ratio as descriptor of particle size and shape in sediment hydrodynamics
items: Diamond is the new Green—Why Green Open Access is not a sustainable long-term model for scientific publishing
items: Origin and composition of the Siderolithic Group, Geneva Basin (GEo-02 well)
items: Along-strike variability of fault-controlled deltaic systems (Crati Basin, southern Italy)
items: Data-driven lithofacies prediction of unconsolidated sediments from wireline logs
items: Wet snow avalanches on Corsica Island: a long-term perspective from lake sediments
items: Integrating chemostratigraphy and sedimentology for sequence stratigraphy in an enigmatic Middle to Late Devonian mudstone
items: Size and shape of carbonate grains: A comparison of measurement techniques
items: SEDucate: sedimentary log exercises for an active learning environment
items: Sedimentologika: a community-driven diamond open access journal in sedimentology
items: New approaches to the architectural analysis of deltaic outcrops: Implications for subsurface reservoir characterization and paleoenvironmental reconstruction
items: Tectonic, eustatic and climate controls on facies architecture during the transition to the Neoproterozoic icehouse in the Adelaide Superbasin, Australia
items: Submarine crevasse lobes controlled by lateral slope failure in tectonically-active settings: an exhumed example from the Eocene Aínsa depocentre (Spain)
items: Source-to-sink controls on modern fluvial sands in the Pantanal back-bulge basin (Brazil)
items: Geochronology of reworked ash and its implications for accommodation space variations in distal foreland basins, McMurray Formation, Alberta, Canada
items: Constraining the formation conditions of modern pisoids at Ore Lake, Michigan
items: New insights into the early Bajocian (Middle Jurassic) carbon cycle perturbation
items: Sand dune migration and flux into the lower Helmand and Arghandab valleys

Mazon Creek-type Lagerstätten in Pennsylvanian Coal Basins of the US Midcontinent: Biotic Associations and Depositional Frameworks
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description: The Mazon Creek fossil beds of northern Illinois are famous for producing some of the world’s best-preserved fossils from the Pennsylvanian Period, about 307 million years ago. These fossils are found inside ironstone (siderite) concretions that formed rapidly around plants and animals as they were buried. Because of this unusual style of preservation, even soft-bodied creatures—like jellyfish, worms, and the mysterious “Tully Monster”—survive in remarkable detail. For decades, the Mazon Creek has been known for two distinct fossil communities: the plant-rich Braidwood association from nearshore environments, and the more marine Essex association full of jellyfish, shrimps, and other sea life. This study brings together the largest systematic sampling effort ever conducted at Mazon Creek—over 300 000 concretions collected from more than 350 sites—and compares them with new fossil discoveries from similar rocks across Illinois, Indiana, Missouri, and Oklahoma. We combine detailed descriptions of the preserved fossil assemblages, and show them to represent real, repetitive ecological groupings shaped by ancient environmental gradients. Our work also demonstrates that Mazon Creek-style fossil deposits are not unique to Illinois: similar environments and fossil communities occurred widely across the ancient U.S. Midcontinent as well as in Europe. These findings help us understand how rapid sea-level rise, coastal flooding, and tidal currents created the conditions that allowed such exceptional fossil preservation, offering a window into ancient ecosystems rarely preserved in the rock record.
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creator: Gordon Baird
creator: James Schiffbauer
creator: Gigi Feltmann
creator: Casey Bennett
creator: Natalia Bykova
rights: Copyright (c) 2026 Gordon C. Baird, James Schiffbauer, Gigi Feltmann, Casey C. Bennett, Natalia Bykova https://creativecommons.org/licenses/by/4.0
date: 2026-08-07
publication date: 2026-08-07
doi: 10.57035/journals/sdk.2026.e42.2455

Seismic, tomographic and oceanographic insights into water mass interactions and sediment stability on the Demerara Plateau
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description: Investigating the origins of large submarine landslides along seismically inactive continental margins is crucial in assessing tsunami risks in coastal regions. In this study, we use a combination of multi-channel seismic, seismic tomographic, oceanographic, expendable bathythermograph and remote sensing data along the eastern Demerara Plateau, located offshore French Guiana and Surinam. We aimed to image the deep-water processes responsible for the repeated landslides originating from a 350 km continuous head-wall scarp located along the plateau. Our comprehensive dataset enables us to expand the spatio-temporal coverage of water column observations, allowing the identification of a strong pycnocline between the Antarctic Intermediate Water and the North Atlantic Deep-Water. We also image a North Brazil Current associated eddy along the Demerara Plateau slopes. Within the seismically inactive context of the plateau, we propose that the interactions between water masses and sedimentary layers may trigger submarine landslides identified along the margin.
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creator: Thomas Lesourd–Laux
creator: Frauke Klingelhoefer
creator: Walter Roest
creator: Lies Loncke
creator: Ivane Pairaud
creator: Paul Blin
creator: Philippe Schnurle
creator: David Graindorge
creator: Christophe Basile
rights: Copyright (c) 2026 Thomas Lesourd–Laux, Frauke Klingelhoefer, Walter Roest, Lies Loncke, Ivane Pairaud , Paul Blin, Philippe Schnurle, David Graindorge, Christophe Basile https://creativecommons.org/licenses/by/4.0
date: 2026-07-23
publication date: 2026-07-23
doi: 10.57035/journals/sdk.2026.e42.1820

Straits: stargates for the future
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description: The current economic and geopolitical scenario, once again, indicates straits as the focus of international headlines. These narrow passageways have an impact on the global economy, but foremost they are ecological, environmental and geological elements fundamental for the future of Earth and its environments. A better understanding of their role, evolution and peculiarities is needed.
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creator: Domenico Chiarella
creator: Sergio Giuseppe Longhitano
rights: Copyright (c) 2026 Domenico Chiarella, Sergio Giuseppe Longhitano https://creativecommons.org/licenses/by/4.0
date: 2026-08-06
publication date: 2026-08-06
doi: 10.57035/journals/sdk.2026.e42.2550

Integrating field-based and digital datasets to improve geometric accuracy of geologic cross sections constructed from outcrop
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description: Outcrop exposures of sedimentary rocks preserve vital records of depositional processes and offer key insights into Earth's depositional history. Traditional field-based techniques, such as measuring bed orientations, sketches, and field photography, have long been used to document stratigraphic patterns, while modern approaches now leverage high-resolution panoramas and drone-based photogrammetry to quantify and geolocate measurements. Although Digital Outcrop Models (DOMs) derived from UAVs (drones) markedly improve our ability to capture and interpret spatial details, these modern approaches, when used to generate 2-D stratigraphic correlation panels, are still challenged by distortions caused by outcrop perspective and structural deformation. To accurately constrain stratigraphic reconstructions derived from DOMs, calibrated field data is necessary to corroborate these observations with thicknesses, length scales, and lithologies. Here, we present a method to correct stratigraphic interpretations from DOMs for structural overprint and outcrop perspective using field-based paleocurrent and strike-and-dip measurements to produce geometrically accurate surface length, height, and dip in stratigraphic correlation panels. We demonstrate this method on Cerro Cazador, a 15 km-long outcrop transect in Patagonia, Chile, recognized as containing continental shelf and shelf-margin sedimentary deposits. By systematically comparing three data projection strategies: no correction, a single correction, and a novel multi-correction workflow that applies localized adjustments to distinct structural regions, we show that the multi-correction method yields depositional geometries consistent with expected stratigraphic patterns (e.g., flat topset and bottomset deposits, sloping foresets, shelf-edge trajectories). These findings underscore the need for incorporating field-based calibrations into drone-derived models to accurately capture depositional patterns in geologically complex…
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creator: Thomas G. E. Peploe
creator: Paul R. Nesbit
creator: Rebecca G. Englert
creator: Miquel Poyatos-Moré
creator: Brian W. Romans
creator: Lisa Stright
creator: Stephen M. Hubbard
rights: Copyright (c) 2026 Thomas G. E. Peploe, Paul R. Nesbit, Rebecca G. Englert, Miquel Poyatos-Moré, Brian W. Romans, Lisa Stright, Stephen M. Hubbard https://creativecommons.org/licenses/by/4.0
date: 2026-07-19
publication date: 2026-07-19
doi: 10.57035/journals/sdk.2026.e42.2385

Transition from wave- to tide-dominated estuary: An example from the Eocene Urahoro Group, eastern Hokkaido, northern Japan
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description: Estuarine morphologies are commonly classified into two end-member categories based on dominant sediment transport processes: wave-dominated and tide-dominated estuaries. Although estuaries are generally presumed to retain their fundamental morphotypes throughout their evolutionary history, this study presents the first documented ancient example of a morphological transition from a wave-dominated to a tide-dominated estuary, identified in the Eocene Urahoro Group in eastern Hokkaido, Japan. A three-dimensional outcrop model was utilized to generate continuous stratigraphic columns extending into the upper parts of the outcrop for detailed facies analysis. Seven facies were identified and grouped into three stratigraphically successive facies associations: (1) a braid plain association characterized by braided river channels and floodplain deposits; (2) a wave-dominated estuary association comprising bayhead delta, central basin, and flood-tidal delta deposits; and (3) a tide-dominated estuary association consisting of tidal sand bar and tidal flat deposits. The transition from wave- to tide-dominated estuary is recorded within a relatively thin (c. 150 m) stratigraphic succession and represents a short-lived depositional shift without significant temporal hiatus. This indicates that the transition occurred at a parasequence to parasequence-set scale, rather than reflecting long-term, basin-wide reorganization. This study proposes a hypothesis to explain this unusual evolutionary transition: an accelerated relative sea-level rise, likely driven by tectonic subsidence, enhanced tidal influences associated with increased tidal prism, causing barrier disintegration within the initially wave-dominated estuarine system. These findings emphasize the potential for more drastic morphological changes in estuarine systems than previously recognized, providing critical insights into predicting estuarine responses to future environmental changes.
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creator: Ryusei Sato
creator: Hajime Naruse
rights: Copyright (c) 2026 Ryusei Sato, Hajime Naruse https://creativecommons.org/licenses/by/4.0
date: 2026-07-14
publication date: 2026-07-14
doi: 10.57035/journals/sdk.2026.e42.2269

A lee-side cavity fill diamicton under the Durance valley glacier: Insights from hoodoos of the Remollon Arch, Southern French Alps
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description: Deep and narrow gullies dissecting reliefs of the Southern French Alps are filled with 10's to 100's meters thick accumulation of unsorted, boulder-rich muddy material (i.e., diamicton) left behind by glaciers that repeatedly covered the region during Pleistocene glaciations. The modern erosion and removal of this diamicton forms renowned peculiar hoodoo landscapes. Internal stratigraphic architectures in the diamicton show clinothems with topsets unconformably overlying steep, up to 20°, foresets dipping in the inferred down-ice direction. Interpretation of depositional processes reveals subglacial till in topsets, alternations of glaciogenic cohesive debris flows and more turbulent density flows in foresets and occasional glacio-lacustrine muds with ice-rafted debris at the toe of the foresets. We interpret this diamicton as a lee-side cavity fill. In alpine ice caps, ice flow can be accommodated by the deformation of a plastic subglacial till that can be advected in subglacial topographic depressions behind an obstacle made by resistant lithology, i.e., in a pressure shadow zone regarding the ice-flow direction, referred to as lee-side cavity. Lee-side cavity fills are rarely documented in the literature, with existing references limited to subglacial settings beneath ice sheets. To date, no such features have been reported in alpine glacier environments. Recognizing this process expands the range of known subglacial mechanisms active beneath alpine ice caps, offering new insights into how these processes shape modern landscapes.
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creator: Pierre Dietrich
creator: Alexis Nutz
rights: Copyright (c) 2026 Pierre Dietrich, Alexis Nutz https://creativecommons.org/licenses/by/4.0
date: 2026-07-14
publication date: 2026-07-14
doi: 10.57035/journals/sdk.2026.e42.2386

Evolution of a Tethyan carbonate platform through the Jurassic tectonic and climatic upheavals
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description: This study aims to quantify the response of carbonate producers to eustasy, tectonics and climate changes in intracontinental basins. We examined Middle to Late Jurassic carbonate systems (Aalenian to Oxfordian, c. 175 to 155 Ma) of the northern Aquitaine Basin (France). The detailed description of 67 outcrops and the large-scale correlation of 21 transgressive-regressive cycles allows for reconstruction of various evolving depositional environments. A westward dipping carbonate ramp developed from the Aalenian to Early Oxfordian, replaced by a rimmed-platform during the Middle to Late Oxfordian. Accommodation space indicates long wavelength flexures, locally disrupted by normal fault activity, that could relate to the extension of the western Tethys margin or the opening of the North Atlantic Ocean. The Aalenian and Callovian to Early Oxfordian display low carbonate accumulation rates (≈ 10 m Myr−1) that result from (1) limited accommodation space during the Aalenian, possibly caused by the “Mid Cimmerian” uplift, and (2) the development of a wet climate during the Callovian to Early Oxfordian, which enhanced continental weathering and siliciclastic input. The Late Bajocian, Bathonian and Middle to Late Oxfordian are stages of high neritic carbonate production, ranging from 25 to 70 m Myr−1 on the shallow platform. The thriving of ooid, photozoan and ‘Micrite and Microbial’ (M)-factories was favored by a dry climate disturbed by short episodes of intense precipitation in the Tethyan realm, leading to oligo-mesotrophic waters and calcium carbonate supersaturation. The M-factory flourished in lagoons throughout the Middle Jurassic and Oxfordian, independent of climate and tectonic upheavals.
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creator: Quentin Deloume
creator: Simon Andrieu
creator: Éric Lasseur
creator: Thierry Pélissié
creator: Églantine Husson
creator: Benjamin Brigaud
rights: Copyright (c) 2026 Quentin Deloume, Simon Andrieu, Éric Lasseur, Thierry Pélissié , Églantine Husson, Benjamin Brigaud https://creativecommons.org/licenses/by/4.0
date: 2026-04-24
publication date: 2026-04-24
doi: 10.57035/journals/sdk.2026.e41.1928

Diagenetic evolution and reservoir quality of Aptian lacustrine reworked carbonates from the Santos Basin, Brazilian pre-salt
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description: Pre-salt carbonate reservoirs of the Santos Basin, eastern Brazilian margin, contain giant hydrocarbon accumulations, with reworked deposits constituting the highest-quality reservoirs across several oilfields. Despite their importance, the diagenetic evolution of the lacustrine reworked deposits remains poorly understood. This study investigates the diagenetic patterns and controls on reservoir quality of the reworked deposits of the Aptian Barra Velha Formation through integrated petrography, fluid inclusions, petrophysical, and micro-computed tomography (µCT) analyses. Reservoir petrofacies were characterized according to the main controls on porosity evolution, which comprised: dolomitization, silicification, and compaction. Dolomite and silica precipitation took place in a multi-phase scheme, as evidenced by paragenetic relations, and by fluid inclusions data showing heterogeneous entrapment with wide homogenization temperature ranges. Blocky dolomite precipitated both before and after compaction, while late saddle dolomite formed during deeper burial. At least two eodiagenetic silicification phases occurred, followed by late diagenetic coarse quartz precipitation. The relative timing between compaction and eodiagenetic dolomite, silica and calcite precipitation fundamentally controls reservoir quality in the reworked rocks. Mesodiagenetic and hydrothermal processes had subordinate influence on porosity evolution. Reworked rocks show greater susceptibility to compaction than in situ rocks, owing to the more stable crystalline framework of the latter. This study provided essential insights to improve the reservoir characterization and optimize the development strategies for the pre-salt accumulations, as well as for understanding the diagenetic evolution of intraclastic lacustrine carbonates worldwide.
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creator: Mariane Cristina Trombetta
creator: Sabrina Danni Altenhofen
creator: Jaques Soares Schmidt
creator: William da Silveira Freitas
creator: Rosalia Barili
creator: Amanda Goulart Rodrigues
creator: Luiz Fernando De Ros
rights: Copyright (c) 2026 Mariane Cristina Trombetta, Sabrina Danni Altenhofen, Jaques Soares Schmidt, William da Silveira Freitas, Rosalia Barili, Amanda Goulart Rodrigues, Luiz Fernando De Ros https://creativecommons.org/licenses/by/4.0
date: 2026-04-16
publication date: 2026-04-16
doi: 10.57035/journals/sdk.2026.e41.2335

Beyond single-cause models: Investigating variable pathways to submarine fan architectures in the Golo Fan system
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description: Traditional sequence stratigraphy has largely linked submarine fan formation to relative sea-level changes during lowstand conditions. However, these interpretations may oversimplify the system's complexity by overlooking the contributions of other external and internal controls, such as sediment supply variability, tectonics, and autogenic dynamics. This study employs Lobyte3D, a reduced-complexity stratigraphic forward model, combined with genetic algorithm optimization, to systematically explore the impact of extrinsic factors, including sediment input, basin confinement, and oscillation periodicity on fan development. The results demonstrate that similar depositional architectures can emerge under diverse conditions. Sensitivity analyses reveal that depositional features traditionally linked to lowstands, such as lobate geometries and channelized sediment pathways, can also form under highstand or transgressive conditions. These findings challenge the single-cause scenario interpretative paradigms in sequence stratigraphy by demonstrating the equifinality of depositional processes, emphasizing the need for multivariate and probabilistic approaches in practical predictions of fan development.
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creator: Ibrahim Tahiru
creator: Peter Burgess
creator: Christopher Stevenson
rights: Copyright (c) 2026 Ibrahim Tahiru, Peter Burgess, Christopher Stevenson https://creativecommons.org/licenses/by/4.0
date: 2026-04-09
publication date: 2026-04-09
doi: 10.57035/journals/sdk.2026.e41.1845

Depositional model for the spatiotemporal evolution of a mixed carbonate-siliciclastic icehouse system: Pennsylvanian Strawn Group, Eastern Shelf, Permian Basin, USA
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description: Mixed carbonate-siliciclastic depositional systems are enigmatic with unique stratal patterns that are poorly understood and poorly represented in models that do not adequately represent complex tectonic, glacioeustatic, and sediment sourcing and routing controls. The Pennsylvanian Strawn Group, Eastern Shelf, Permian Basin, Texas, USA, is composed of a highly heterogeneous mixed ramp to proximal-shelf deltaic strata ideal for investigation of mixed system evolution in an icehouse regime. Analyses of Upper Strawn wireline logs and drill cores along a transect spanning three oil and gas fields in King County reveal a wide variety of facies attributed to many depositional environments, including ripple to trough cross-bedded, sand-dominated to heterolithic, commonly bioturbated sandstones (tidally modified delta and associated subenvironments), ooid grainstones (shallow marine shoal), phylloid algal bafflestones/boundstones (bioherm buildup), skeletal-peloidal wackestones/packstones (carbonate-dominated shallow marine low-energy), shaly carbonate and siliciclastic mudstones (offshore/deepwater), and paleosols (terrestrial). The facies and their stacking patterns have few shared characteristics between the fields, and elements of each field challenge traditional models for mixed systems. This heterogeneity can be explained with a modified depositional model ICCE-T (icehouse carbonate-clastic evolution in tectonically influenced systems model), which is tuned for icehouse mixed systems deposited in tectonically active regions. The ICCE-T model invokes differential topography, incompletely filled highstand accommodation, and high-amplitude, high-frequency sea level oscillations as mechanisms producing increasingly convoluted bathymetry through time. As sediments do not fill all accommodation within a sequence across the study area, complex topography is maintained, and positive topographic features are abandoned, reused, or reactivated at different relative sea levels. T…
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creator: Kelly Hattori
creator: Peter Flaig
creator: Gregory Wahlman
rights: Copyright (c) 2026 Kelly Hattori, Peter Flaig, Gregory Wahlman https://creativecommons.org/licenses/by/4.0
date: 2026-04-09
publication date: 2026-04-09
doi: 10.57035/journals/sdk.2026.e41.2288

New insights on the depositional environment and dynamics of the lowermost Triassic in Svalbard: linking the Sørkapp-Hornsund High to western and central Spitsbergen
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description: The area now known as the Barents Shelf region was strongly impacted by the End-Permian Mass Extinction and a fundamental reorganisation of source-to-sink systems along the northern margin of Pangaea. Here we integrate new sedimentological, ichnological, chemostratigraphic, and provenance data from western Spitsbergen, collected at Festningen, Reinodden, and the Sørkapp-Hornsund High (Hornsundneset, southern Spitsbergen), to reconstruct the timing and drivers of Early Triassic basin evolution. At Festningen and Reinodden, the sharp but conformable transition from Permian spiculitic Kapp Starostin Formation strata to siliciclastic mudstones and sandstones of the Lower Triassic Vardebukta Formation coincides with the onset of the negative δ13Corg excursion. The Vardebukta Formation preserves seven stacked transgressive–regressive packages within an Induan-age interval of ca 1.2 to 1.6 Myr. Individual cycle durations (ca 177 to 225 kyr) are incompatible with a single dominant Milankovitch component and instead suggest bundling of orbital frequencies and/or strong autogenic modulation of accommodation and sediment supply. On the Sørkapp-Hornsund High, a 75 Myr hiatus above Mississippian continental deposits is terminated by a 10 to 15 cm thick bentonitic tephra bed linked to the Siberian Traps Large Igneous Province. This is overlain by Induan-age polymictic alluvial-fan and ephemeral braided-river conglomerates (Brevassfjellet Beds), on which limited but recurrent vegetation cover developed. Detrital-zircon age spectra from the conglomerates closely match published data from the Vardebukta Formation at Festningen and the Induan-age Parish Bjerg Formation in Greenland, indicating a shared north Greenland Caledonian source and direct sediment routing during the latest Permian and earliest Triassic. These continental conglomerates are capped by fossiliferous shallow-marine limestones of Dienerian age, which are then overlain by the coarsening-upward shelfal succession of …
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creator: Valentin Zuchuat
creator: Julian Janocha
creator: Hannah L. Brooks
creator: Stella Z. Buchwald
creator: Brian Beaty
creator: Lidya G. Tarhan
creator: Albina Gilmullina
creator: Morgan T. Jones
creator: Anja B. Frank
creator: Niko Lahajnar
creator: Lars Eivind Augland
creator: Beverly S. Felten
creator: William J. Foster
rights: Copyright (c) 2026 Valentin Zuchuat, Julian Janocha, Hannah L. Brooks, Stella Z. Buchwald, Brian Beaty, Lidya G. Tarhan, Albina Gilmullina, Morgan T. Jones, Anja B. Frank, Niko Lahajnar, Lars Eivind Augland, Beverly S. Felten, William J. Foster https://creativecommons.org/licenses/by/4.0
date: 2026-04-09
publication date: 2026-04-09
doi: 10.57035/journals/sdk.2026.e41.2413

Settling velocity of sediment grains, Part 1: Natural sediment particles are not ellipsoids
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description: Particle settling velocity has wide application in sedimentology and engineering. The ability to predict settling velocity based on fluid and particle properties is essential for realistic sediment transport models. It is common practice to describe the size and shape of natural sediment grains with an ellipsoidal model. This paper tests the validity of the ellipsoidal model for predicting particle settling velocity for siliciclastic and carbonate sediments. The parameters associated with this model are the ellipsoidal nominal diameter (Dn = (DsDiDl)1/3) and Corey shape factor (CSF=Ds/(DiDl)1/2), calculated from the short (Ds), intermediate (Di), and long (Dl) axial diameters. An equation for the drag coefficient (i.e., nondimensional friction) expressed as a function of particle Reynolds number (i.e., nondimensional particle size) and Corey shape factor (i.e., ellipsoidity) was reconstructed for siliciclastic and carbonate grains separately, based on the largest available compilations of existing datasets (639 siliciclastic and 3 666 carbonate grains). The ellipsoidal approximation of grain size yields significant errors in settling velocity predictions, yet the equation is more accurate for siliciclastic particles (mean absolute error = 14 %) than for carbonate grains (mean absolute error = 21 %). This difference is explained by the enlarged irregularity of particles in carbonate compared to siliciclastic sediments, due to enhanced angularity and surface roughness of skeletal remains. Thus, the ellipsoidal model, using the nominal diameter and Corey shape factor, is not suitable for describing natural sediments or predicting their settling velocity, despite its widespread use. A companion paper (Part 2, Slootman et al., 2026) investigates alternative particle size and shape descriptors.
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creator: Arnoud Slootman
creator: Max De Kruijf
creator: Guenther Glatz
creator: Joris Eggenhuisen
creator: Zane Jobe
creator: John Reijmer
rights: Copyright (c) 2026 Arnoud Slootman, Max De Kruijf, Guenther Glatz, Joris Eggenhuisen, Zane Jobe, John Reijmer https://creativecommons.org/licenses/by/4.0
date: 2026-03-26
publication date: 2026-03-26
doi: 10.57035/journals/sdk.2026.e41.1937

Settling velocity of sediment grains, Part 2: Volume/area ratio as descriptor of particle size and shape in sediment hydrodynamics
type: item
description: Particle settling velocity is a fundamental property for sediment hydrodynamics with implications for sedimentology and engineering. Settling velocity depends on fluid properties and the density and dimensions of sediment grains. However, it is not self-evident what length variable should be chosen to represent particle size and shape in settling velocity equations. A companion paper (Part 1) demonstrated that the ellipsoidal model as defined by the nominal diameter and a shape factor are unsuitable for the description of natural sediment particle dimensions. Mathematical derivation from the balance of forces between particle weight and fluid friction reveals that terminal settling velocity should be a function of particle volume and its maximum projection area. In this paper (Part 2) several candidates for a parameter representing particle dimensions in the settling problem are tested, including the diameters of the nominal and equivalent spheres, and the volume/area ratios of the bounding-box ellipsoidal model and the realistic particle model. The latter is obtained from high-resolution micro-computed tomography for 203 irregular skeletal carbonate grains, providing accurate ratios of particle volume over maximum projection area. This ratio predicts settling velocity more accurately than the other tested variables of particle size. Thus, the volume/area ratio captures both particle size and shape, which are usually modelled separately. This study proposes a new framework for accurate hydrodynamic characterisation of sediment particles.
subject: Publications
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subject: Research Articles
  topic: category
subject: Array
  topic: keywords
subject: Array
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subject: Array
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subject: Array
  topic: keywords
creator: Arnoud Slootman
creator: Max De Kruijf
creator: Guenther Glatz
creator: Joris Eggenhuisen
creator: Zane Jobe
creator: John Reijmer
rights: Copyright (c) 2026 Arnoud Slootman, Max De Kruijf, Guenther Glatz, Joris Eggenhuisen, Zane Jobe, John Reijmer https://creativecommons.org/licenses/by/4.0
date: 2026-03-26
publication date: 2026-03-26
doi: 10.57035/journals/sdk.2026.e41.2307

Diamond is the new Green—Why Green Open Access is not a sustainable long-term model for scientific publishing
type: item
description: In recent decades, the academic publishing world has aimed to transition from a paywall-dominated system to Open Access (OA). While OA seeks to make scientific knowledge freely available, the sustainability of current models remains debated. This article examines the three main OA publishing routes (Green, Gold and Diamond) and argues that, while Green OA offers short-term accessibility benefits, it perpetuates dependence upon for-profit publishers and fails to address systemic inequities. Gold OA shifts financial responsibility to authors through high article processing charges (APC), further exacerbating disparities. In contrast, Diamond OA, driven by community-led initiatives and supported by open infrastructures, eliminates APC, ensures equitable access, and allows authors to share their work freely. We highlight successful examples in geosciences and discuss the cultural and structural barriers that still hinder adoption, despite Diamond OA representing the most sustainable, fair and accessible long-term model for scholarly publishing.
subject: Publications
  topic: section
subject: Opinion Pieces
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creator: Romain Vaucher
creator: Camille Thomas
rights: Copyright (c) 2026 Romain Vaucher, Camille Thomas https://creativecommons.org/licenses/by/4.0
date: 2026-03-03
publication date: 2026-03-03
doi: 10.57035/journals/sdk.2026.e41.2397

Origin and composition of the Siderolithic Group, Geneva Basin (GEo-02 well)
type: item
description: This study provides new insights into the Siderolithic Group, a 158 m -thick sedimentary succession deposited within a regionally extensive karstified unconformity spanning tens of square kilometres. This unconformity marks the Cretaceous-Paleogene boundary, with a stratigraphic gap of about 94 Myr, ranging from the Lower Cretaceous (Barremian–Aptian) to (likely) the Bartonian (Eocene). Using borehole data from the GEo-02 geothermal exploration well in the Geneva Basin, our study integrates petrography, mineralogy, geochemistry, and petrophysical analyses of 139 samples to reconstruct the evolution of this complex depositional system. Six sedimentological subunits were identified, representing distinct phases of karst evolution, from initial formation to infill and subsequent diagenesis. Variations in gamma ray values suggest fluctuating water levels within the karst system, while the heterogeneous distribution of quartz grains indicates detrital sediment input from both aeolian and fluvial sources. The mineral assemblage, dominated by siderite, chlorite, and kaolinite, reflects diagenetic processes under reducing conditions, with siderite facilitating kaolinite chloritisation in the presence of quartz. Geochemical data and clay mineral data indicate humid climatic conditions during deposition. The Siderolithic Group is inferred to be of Bartonian age based on biostratigraphic constraints from analogue deposits on the Swiss Plateau, suggesting its deposition during the Middle Eocene Climatic Optimum (MECO). This study provides one of the few continental records of the MECO in Western Europe, recording high mercury content possibly related to the flare-up in Neotethys subduction zone volcanism.
subject: Publications
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subject: Research Articles
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subject: Array
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creator: Aurélia Crinière
creator: Yasin Makhloufi
creator: Ovie Emmanuel Eruteya
creator: Andrea Moscariello
rights: Copyright (c) 2026 Aurélia Crinière, Yasin Makhloufi, Ovie Emmanuel Eruteya, Andrea Moscariello https://creativecommons.org/licenses/by/4.0
date: 2026-01-20
publication date: 2026-01-20
doi: 10.57035/journals/sdk.2026.e41.1914

Along-strike variability of fault-controlled deltaic systems (Crati Basin, southern Italy)
type: item
description: Normal fault growth models are largely based on the geometric relationship between fault displacement and length, and the seismically imaged record of accommodation development contained within syn-rift strata. However, it is possible to infer variations in the style of normal fault growth across poorly exposed faulted margins through the analysis of the sedimentology and stratigraphic architecture of the associated syn-rift deposits. Here, we analyze the stratigraphic and along-strike variability of normal-fault controlled deltaic systems to infer the evolution of their related basin-margin fault system, for which the geometry and displacement patterns are poorly constrained. The Crati Basin (southern Italy) contains Pleistocene syn-rift deposits exposed in the hangingwall of a c. 45 km-long normal fault system. We show that during an early extensional phase, shelf-type deltas were deposited along the entire strike length of the fault system, suggestive of relatively shallow water depths and early establishment of fault length. In contrast, a later extensional phase resulted in the deposition of Gilbert-type deltas at the center and towards the northern end of the fault system, whereas shelf-type deltas persisted near the system southern tip; this stratigraphic evolution records the transition to a period when the fault system growth was characterized by displacement accumulation rather than lengthening. We show that the detailed sedimentological and stratigraphic analysis of exposed ancient deltaic systems can be used to discriminate between models for normal fault growth and that, conversely, displacement and accommodation variations along normal faults control the styles and depositional architecture of deltaic systems in extensional settings.
subject: Publications
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subject: Research Articles
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creator: Candela Martínez
creator: Christopher A.-L. Jackson
creator: Nicola Scarselli
creator: Sergio Longhitano
creator: Francesco Muto
creator: Domenico Chiarella
rights: Copyright (c) 2026 Candela Martínez, Christopher A.-L. Jackson, Nicola Scarsello, Sergio Longhitano, Francesco Muto, Domenico Chiarella https://creativecommons.org/licenses/by/4.0
date: 2026-01-18
publication date: 2026-01-18
doi: 10.57035/journals/sdk.2026.e41.1927

Data-driven lithofacies prediction of unconsolidated sediments from wireline logs
type: item
description: Detailed knowledge of the lithostratigraphy of unconsolidated sediments is essential for many scientific and industrial applications. Although drill cores provide lithological and petrophysical information (e.g., lithofacies, permeability, consolidation), core recovery is time- and resource-intensive. In contrast, flush drillings are faster and less expensive but lack detailed geological context. Therefore, combining the advantages of both methods can significantly enhance subsurface investigations while reducing reliance on costly core drillings. This study explores the use of unsupervised machine learning to build data-driven stratigraphic models from standard petrophysical and geochemical wireline logging data. Specifically, it applies dimensionality reduction (UMAP) and hierarchical clustering to identify distinct lithofacies types. The method was tested on datasets from the former Rhine Glacier area in Germany, including one core-controlled well and a nearby flush-drilled borehole. The developed workflow predicted the lithofacies of the core-controlled well with ~76% accuracy, capturing both major stratigraphic units and finer internal features, directly linking them with the geology identified at the drilled site. This allows linking the reconstructed lithology of the core-controlled well with the flush-drilled well. The results demonstrate that unsupervised machine learning can significantly improve stratigraphic models of unconsolidated Quaternary sediments using wireline logs, with minimal dependence on core data.
subject: Publications
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subject: Method Articles
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creator: Sebastian Schaller
creator: Patricio Becerra
creator: Sarah Beraus
creator: Marius W. Buechi
creator: David Mair
creator: Mehrdad Sardar Abadi
creator: Bennet Schuster
creator: Flavio S. Anselmetti
rights: Copyright (c) 2025 Sebastian Schaller, Patricio Becerra, Sarah Beraus, Marius W. Buechi, David Mair, Mehrdad Sardar Abadi, Bennet Schuster, Flavio S. Anselmetti https://creativecommons.org/licenses/by/4.0
date: 2025-11-11
publication date: 2025-11-11
doi: 10.57035/journals/sdk.2025.e31.1819

Wet snow avalanches on Corsica Island: a long-term perspective from lake sediments
type: item
description: Mountain areas are very sensitive to climate change, which has led to changes in natural hazards that are often linked to disturbances in the cryosphere. In this context, changes in snowfall characteristics and snow cover affect avalanche hazards. Long-term variability can be reconstructed by using historical archives, tree rings and, more rarely, lake sediments. The latter approach is based on the identification of lake sediment consisting of poorly sorted, coarse sediments in a fine matrix, which are often associated with terrestrial organic debris. This sediment is generally brought to the lake within large amounts of wet snow, or via ‘drop stones’ when the ice melts if the avalanche takes place on a frozen surface. Here, we study two high-altitude lakes (Melu and Capitellu) in the Restonica Valley in Corsica, an area where systematic records are lacking, to reconstruct signals related to such large wet snow flows on a millennial scale. The analysis of several sedimentological and geochemical markers enables the characterization of wet avalanche deposits in the two lakes, as well as turbidite-type facies linked to historical earthquakes in Corsica. Age models based on short-lived radionuclides and radiocarbon also make it possible to reconstruct two avalanche chronologies covering 600 and 1750 years in Melu and Capitellu Lakes, respectively, which show similar temporal variations. A comparison with the only long-term chronology available in the Alps (Lake Muzelle, Ecrins) also reveals synchronicity in the secular variability of avalanches, suggesting a common forcing between Corsica and the Alps. Human observations and accident records from recent decades, and snow and weather release conditions reconstructed from a hydrological modeling scheme confirm the ability of the lacustrine avalanche sedimentary method to document local wet snow avalanche activity. The proposed methodology, which is based on paleolimnological studies, may therefore be useful, alone or com…
subject: Publications
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subject: Research Articles
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creator: Pierre Sabatier
creator: Pierre Brigode
creator: Alix Bisquert
creator: Nicolas Eckert
creator: Florie Giacona
creator: Michael Deschâtres
creator: Victorien Bauve
creator: Maëlle Kelner
creator: Maxime Debret
creator: Marie-Charlotte Bellingery
creator: Yoann Copard
creator: Emmanuel Malet
creator: Julien Didier
creator: Frédéric Huneau
creator: Emilie Garel
creator: Boris Vannière
rights: Copyright (c) 2025 Pierre Sabatier, Pierre Brigode, Alix Bisquert, Nicolas Eckert, Florie Giacona, Michael Deschâtres, Victorien Bauve, Maëlle Kelner, Maxime Debret, Marie-Charlotte Bellingery, Yoann Copard, Emmanuel Malet, Julien Didier, Frédéric Huneau, Emilie Garel, Boris Vannière https://creativecommons.org/licenses/by/4.0
date: 2025-11-04
publication date: 2025-11-04
doi: 10.57035/journals/sdk.2025.e31.1669

Integrating chemostratigraphy and sedimentology for sequence stratigraphy in an enigmatic Middle to Late Devonian mudstone
type: item
description: Sequence stratigraphy in fine-grained successions is often challenging with traditional datasets, and in such intervals, chemostratigraphy is increasingly used to facilitate interpretations. In this study, we present an example from mudstone units of the Horn River Group (Northwest Territories, Canada), which provide a local record of Middle to Late Devonian marine conditions. The dataset comprises geochemical composition data from X-ray fluorescence (XRF), mineralogical data from X-ray diffraction (XRD), wireline logs, total organic carbon (TOC) profiles, and lithological core and thin section descriptions. We first focus on a mudstone core with high-resolution thin-section and geochemical results, enabling the evaluation of chemostratigraphic signatures associated with surfaces and systems tracts in the Horn River Group. By employing chemostratigraphic proxies for terrigenous sediment supply and proportion of biogenic silica, sequence stratigraphic analysis is extended to three cores and five outcrops lacking extensive thin section coverage. Six complete transgressive–regressive (T–R) sequences are identified and correlated in the Horn River Group, comprising higher-resolution cycles in relative sea-level and sediment supply, which are superimposed on previously identified larger-scale sequences. The sequence stratigraphic framework presented illustrates the local balance between relative sea-level rise and sediment supply along the northwestern margin of Laurentia during the Eifelian to the Frasnian. Moreover, this study demonstrates the utility of integrating chemostratigraphic proxies with sedimentological results as a means of sequence stratigraphic interpretation and correlation in mudstone intervals.
subject: Publications
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subject: Research Articles
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creator: Maya T. LaGrange
creator: Brette S. Harris
creator: Sara K. Biddle
creator: Smriti Dhiman
creator: Octavian Catuneanu
creator: Kurt O. Konhauser
creator: Viktor Terlaky
creator: Murray K. Gingras
rights: Copyright (c) 2025 Maya T. LaGrange, Brette S. Harris, Sara K. Biddle, Smriti Dhiman, Octavian Catuneanu, Kurt O. Konhauser, Viktor Terlaky, Murray K. Gingras https://creativecommons.org/licenses/by/4.0
date: 2025-11-02
publication date: 2025-11-02
doi: 10.57035/journals/sdk.2025.e31.1695

Size and shape of carbonate grains: A comparison of measurement techniques
type: item
description: Grain size and shape significantly influence sediment transport and deposition, so accurate characterization is essential for understanding depositional dynamics. Biogenic carbonate grains, such as skeletal fragments, exhibit irregular morphologies that challenge traditional, single-diameter-based size estimates. To better characterize these non-spherical grains, two- or three-dimensional analyses are required. Micro-computed tomography (micro-CT) offers high-resolution, three-dimensional models of individual grains, enabling accurate quantification of volume, projection area, and shape. However, the high cost and limited accessibility of micro-CT in standard sedimentology labs hinder its widespread use. This study compares caliper measurements, sieve analysis, static image analysis (SIA), and dynamic image analysis (DIA) against a micro-CT reference dataset for sand-sized skeletal carbonate grains. We assess the accuracy of each method in capturing key grain properties relevant for hydrodynamic and geomechanical modeling, including volume, maximum projection area, nominal diameter, and Corey shape factor. We also evaluate the potential of predicting a grain’s third dimension based on its maximum projection dimension, as measured through SIA of loose grains and thin sections. A regression model comparing SIA to known micro-CT values yields 72–78% accuracy. Results show that methods relying on axial dimensions systematically overestimate volume and maximum projection area. DIA tends to oversimplify grains as spherical, while SIA on thin sections may underestimate grain size due to slicing orientation effects. This study highlights the advantages and limitations of various measurement techniques and underscores the importance of selecting appropriate grain measurement techniques in sedimentological research.
subject: Publications
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subject: Research Articles
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creator: Chibuzor David Nworie
creator: Zane R. Jobe
rights: Copyright (c) 2025 Chibuzor David Nworie, Zane R. Jobe https://creativecommons.org/licenses/by/4.0
date: 2025-10-30
publication date: 2025-10-30
doi: 10.57035/journals/sdk.2025.e31.1742

SEDucate: sedimentary log exercises for an active learning environment
type: item
description: Active learning in higher education has been shown to improve students’ learning experience by focusing on a student-centered environment. However, the development of realistic activities that simulate the complexity of real world examples while being appropriate for novice learners is challenging. Here we present SEDucate, a GIS plugin to designed to build realistic active-learning exercises for sedimentology courses. SEDucate creates unique sedimentary logs for a tailored assessment based on modern sedimentary environments. The automated creation of simple sedimentary logs covering a variety of depositional environments can be implemented in a wide range of exercises and assessments for individual or group-based work. This novel GIS plugin facilitates teaching the characterization of sedimentary logs, the interpretation of paleogeography and the lateral variation observed in modern sedimentary environments.
subject: Publications
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subject: Method Articles
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creator: Bjorn Nyberg
creator: Henk Keers
creator: Sigrid Næsheim
creator: Lisbeth Vedå
creator: Gary Weissmann
rights: Copyright (c) 2023 Bjorn Nyberg, Henk Keers, Sigrid Næsheim, Lisbeth Vedå, Gary Weissmann https://creativecommons.org/licenses/by/4.0
date: 2023-04-05
publication date: 2023-04-05
doi: 10.57035/journals/sdk.2023.e11.1014

Sedimentologika: a community-driven diamond open access journal in sedimentology
type: item
description: Sedimentologika is a community-driven Diamond Open Access scientific journal for the publication of work in the broad area of sedimentology and stratigraphy. The journal aims to provide a platform to the academic community and broader society, offering and guaranteeing permanent free publication and free access to peer-reviewed scientific studies focusing on all types of sedimentary processes, deposits, and environments across all spatial and temporal scales, on Earth or any other planetary body. It will publish high-quality research that will advance the field of sedimentary science, and will encourage multidisciplinarity, new teaching practices, tools and methods, and progress in accessibility to science. Sedimentologika is part of an ongoing broader Diamond Open Access movement in geosciences aspiring freedom from the financial barriers and pressures of private publishing houses, to provide direct and equal access to science for all citizens, scientists, and institutions worldwide. The published material will include research, review, methodology and opinion articles, which will be free to share, as the authors will retain the copyright of all the submitted material. Manuscripts will be published in English. Authors can attach a second abstract in a language of their choice, further allowing local communities, students, or decisional bodies to access, at least, a summary of the latest research, thus reducing potential language barriers. Sedimentologika follows Open Science principles to promote ethical dissemination and accessibility of science and knowledge, following high equity, diversity and inclusion standards. Sedimentologika emerged as a solution for the scientific community to sidestep structural inequality of the academic publishing system that is becoming financially unsustainable to its payers (authors, funding agencies), and to commit to bibliodiversity. The objective is to ensure that scientific findings remain accessible to all in order to keep adva…
subject: Publications
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subject: Opinion Pieces
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creator: Camille Thomas
creator: Aurelia M-L. J. Privat
creator: Romain Vaucher
creator: Yvonne Spychala
creator: Valentin Zuchuat
creator: Marta Marchegiano
creator: Miquel Poyatos-Moré
creator: Ian Kane
creator: Domenico Chiarella
rights: Copyright (c) 2023 Camille Thomas, Aurelia Privat, Romain Vaucher, Yvonne Spychala, Valentin Zuchuat, Marta Marchegiano, Miquel Poyatos-Moré, Ian Kane, Domenico Chiarella https://creativecommons.org/licenses/by/4.0
date: 2023-04-05
publication date: 2023-04-05
doi: 10.57035/journals/sdk.2023.e11.1015

New approaches to the architectural analysis of deltaic outcrops: Implications for subsurface reservoir characterization and paleoenvironmental reconstruction
type: item
description: This study defines a new workflow to investigate the internal facies architecture of a river-dominated delta deposit using outcrops of the Cretaceous Panther Tongue of the Star Point Sandstone in central Utah, U.S.A. Photorealistic virtual outcrop models (VOM) were created from ~13 linear-km of outcrop. The VOMs, alongside field observations, were used to identify and map facies and facies associations over the ~25 m-thick stratigraphic interval. In order to investigate this system as a potential subsurface reservoir analog, a database of measurements was constructed using 60 digital sections that were measured within the VOMs at 152 m (~500 ft) spacing. This database characterizes a total of 508 sandstone beds by their thickness, length, and dip, from which the average thickness (0.78 m), bed length (330 m), and bed dip (2˚ towards the south) were calculated. Thinning rates were also calculated in both depositional strike and depositional dip directions (1.37x10-2 and 1.01x10-2 respectively). These comparable values suggest that the sandstone beds thin equally laterally and longitudinally from the sediment source, a characteristic typical of modern-day river-dominated deltas. The dataset also includes siltstone unit thickness data, recording an average thickness of 0.81 m, and a trend of increasing siltstone abundance and thickness moving from proximal areas where siltstones comprise 3% of the succession, and 77% in the most distal areas. The impact of observational scale was also investigated by querying the database at multiple physical length scales to include more typical well spacings of 305 and 610 m (500 and 1000 ft). This additional analysis emphasizes the role of variability in lithologically heterogeneous systems and underscores the utility of outcrop analogs to better understand sources of uncertainty. From these data, a series of depositional environment maps was constructed, illustrating the evolution of eight delta lobes that encompass the preserved d…
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creator: Claire E. Atlas
creator: Emma A. Morris
creator: Cari L. Johnson
creator: Anton F.-J. Wroblewski
rights: Copyright (c) 2023 Claire E. Atlas, Emma A. Morris, Cari L. Johnson, Anton F.-J. Wroblewski https://creativecommons.org/licenses/by/4.0
date: 2023-06-19
publication date: 2023-06-19
doi: 10.57035/journals/sdk.2023.e11.1051

Tectonic, eustatic and climate controls on facies architecture during the transition to the Neoproterozoic icehouse in the Adelaide Superbasin, Australia
type: item
description: The Tonian to Cryogenian (ca. 1000–635 Ma) marks a crucial turning point in Earth’s history, where tectonic reorganisation and fluctuating oceanic and atmospheric geochemistry plunged the globe into icehouse conditions. This was followed by a postglacial warming period that delivered large volumes of nutrients to the oceans and stimulated eukaryotic evolution. The Adelaide Superbasin in South Australia hosts a thick repository of Neoproterozoic and lower Cambrian sedimentary successions that preserve the depositional conditions during this unique time. In this study, detailed sedimentological data were collected from over 8,350 m of measured section at seven locations across the northern Flinders Ranges. Tonian deposits reveal a carbonate platform setting, where deposition was controlled by basin geometry and proximity to uplifted source areas. In the early Cryogenian, sedimentary successions were affected by the Sturtian glaciation, characterised by two glacial advance-retreat phases that coincide with climatically driven regression. The end of the Sturtian glaciation was marked by basin subsidence and widespread transgression into a more distal subaqueous environment. Despite the lithostratigraphic and sequence stratigraphic similarity between Tonian–Cryogenian successions globally, their correlation remains contentious. The influence of local tectonic regimes during the Tonian created a potential oceanic restriction between developing basins, which challenges the chemostratigraphic correlation between these deposits. Further, limited geochronological ages and opposing interpretations of glacial cyclicity puts into question the timing and extent of the Sturtian glaciation. Conversely, the post glacial transgression appears to be the most globally consistent as it results from climatically controlled sea level rise that was driven by melting ice sheets.
subject: Publications
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subject: Research Articles
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creator: Georgina M. Virgo
creator: Alan S. Collins
creator: Morgan L. Blades
creator: Kathryn J. Amos
rights: Copyright (c) 2023 Georgina M. Virgo, Alan S. Collins, Morgan L. Blades, Kathryn J. Amos https://creativecommons.org/licenses/by/4.0
date: 2023-08-21
publication date: 2023-08-21
doi: 10.57035/journals/sdk.2023.e11.1083

Submarine crevasse lobes controlled by lateral slope failure in tectonically-active settings: an exhumed example from the Eocene Aínsa depocentre (Spain)
type: item
description: Tectonic deformation and associated submarine slope failures modify seafloor relief, influencing sediment dispersal patterns and the resulting depositional architecture of deep-water systems. The exhumed Middle Eocene strata of the Banastón deep-water system in the Aínsa depocentre, Spain, allow the interplay between submarine slope confined systems, mass flow deposits, and syn-depositional compressional tectonics to be investigated. This study focuses on the Banastón II sub-unit, interpreted as deposits of low-sinuosity and narrow (2-3 km wide) channel-belts confined laterally by tectonically-controlled, fine-grained slopes. The studied succession (111 m-thick) is exposed along a 1.5 km long SE-NW trending depositional dip section and is documented here by facies analysis and physical correlation of 10 measured sections. Results show a stratigraphic evolution in which the channel axes migrated to the southwest, away from a growing structure in the northeastern part of the Aínsa depocentre. Uplift of this structure promoted the breaching of confining channel walls and slope material with mass failures and the development of sand-rich crevasse scour-fills and crevasse lobes. We show that crevasse deposits form an important component of overbank succession. These crevasse lobes are characterized by structureless thick and medium beds that form < 5 m thick packages in proximal parts and thin abruptly over 1 km across strike (NE) and along downdip (NW) into structured thin beds, similar to the heterolithic dominated overbank deposits. Although the development of crevasse lobes has been observed in multiple deep-water systems in ancient and modern systems, this study documents, for the first time, crevasse lobe development on the active compressional margin of a foreland basin rather than on the opposing, more stable and gentler inactive margin. We discuss the mechanism for forming these crevasse deposits, which exploited the accommodation generated by submarine landslid…
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creator: Ander Martinez-Doñate
creator: Euan L. Soutter
creator: Ian A. Kane
creator: Miquel Poyatos-Moré
creator: David M. Hodgson
creator: Ashley J. M. Ayckbourne
creator: William J. Taylor
creator: Max J. Bouwmeester
creator: Stephen S. Flint
rights: Copyright (c) 2023 Ander Martinez-Doñate, Euan L. Soutter, Ian A. Kane, Miquel Poyatos-Moré, David M. Hodgson, Ashley J. M. Ayckbourne, William J. Taylor, Max J. Bouwmeester, Stephen S. Flint https://creativecommons.org/licenses/by/4.0
date: 2023-09-05
publication date: 2023-09-05
doi: 10.57035/journals/sdk.2023.e11.1068

Source-to-sink controls on modern fluvial sands in the Pantanal back-bulge basin (Brazil)
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description: Sedimentological processes are underexplored in retro-arc basin segments of source-to-sink systems, particularly in the distal back-bulge depozone. The extant Pantanal Basin of Latin America is a large sub-tropical continental back-bulge for which the boundary conditions on riverine sedimentation (tectonics, climate, phytogeography) are reasonably understood. Here, we use a new database of riverbed sand samples (n = 97) to investigate the modern provenance of the Pantanal Basin. Petrographic analysis of grain-mounted thin sections and Gazzi-Dickinson point counting were used to assess the framework composition of the sands, and a pour point analysis based on geographic information systems (GIS) defined the hinterland geological environment for each sample. Six provenance domains were defined: (a) lowlands, (b) Amazon craton, (c) Rio Apa craton, (d) plateau, (e) South Paraguay Belt, and (f) North Paraguay Belt. Most Pantanal samples are quartzose non-orogenic detritus (Qt88\F5\L7). Rivers draining the Paraguay Belt highlands carry more lithic grains derived from carbonate parent rocks. The occurrence of plagioclase grains is rare. However, river sands where >30% of the total assemblage was K-feldspar were present downstream of foliated metamorphic outcrops of the Rio Apa craton. Sand relatively rich in fine K-feldspar grains in the medial Taquari River megafan were attributed to channel avulsion, incision, and reworking of floodplain deposits. Statistical analysis suggests that bedrock lithology and average annual rainfall are important controls on fluvial sands in the Pantanal Basin, with watershed slope, temperature, and dilution playing secondary roles in the spatial distribution of dominant grain types. This study provides new actualistic data that aim to improve interpretations of the geological record.
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creator: Edward L. Lo
creator: Aguinaldo Silva
creator: Sidney Kuerten
creator: Rômullo O. Louzada
creator: Giliane G. Rasbold
creator: Michael M. McGlue
rights: Copyright (c) 2023 Edward L. Lo, Aguinaldo Silva, Sidney Kuerten, Rômullo O. Louzada, Giliane G. Rasbold, Michael M. McGlue https://creativecommons.org/licenses/by/4.0
date: 2023-09-21
publication date: 2023-09-21
doi: 10.57035/journals/sdk.2023.e11.1152

Geochronology of reworked ash and its implications for accommodation space variations in distal foreland basins, McMurray Formation, Alberta, Canada
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description: A bentonite bed consisting of reworked volcanic ash from the Barremian to Aptian lower McMurray Formation is dated using chemical abrasion thermal ionization mass spectrometry (CA-TIMS) on zircon. The bentonite bed is from a cored interval in the McKay Paleovalley in the northern Athabasca Oil Sands Region of Alberta, Canada. Deposition of the lower McMurray Formation took place in the distal portion of the Western Canada Sedimentary Basin early in the Cretaceous-to-Paleocene phase of widespread contractional deformation in the Canadian Cordillera. A 30 g sample of volcanic ash yielded >10,000 very small (<50 µm) zircon grains with the vast majority (~99.7%) being highly abraded and clearly detrital. Twenty-six sharply faceted grains were sufficiently large to be mounted for laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) analysis, which yielded seven Lower Cretaceous dates. These Lower Cretaceous grains were further analyzed using CA-TIMS. The five youngest CA-TIMS dates agree with a weighted mean of 121.51 ± 0.11 Ma which is conservatively interpreted as a maximum depositional age (MDA). The good agreement between the five zircon dates indicates the MDA is probably the depositional age. This study demonstrates that with careful analysis of zircon populations, high-confidence MDAs can be derived even from reworked ash beds that are dominated overwhelmingly by detrital zircon. The date from this study overlaps a previously published MDA of 121.39 ± 0.27 Ma for the top of the lower McMurray Formation in Firebag Tributary in the northeastern Athabasca Oil Sands Area. The overlapping dates establish a widespread chronostratigraphic surface within the northern Athabasca Oil Sands Area. Both ages are from ash beds preserved in coal seams, suggesting that the coal-bearing interval is a regional marker bed and that the ash beds may form an intraformational datum. Further, the occurrence of the ash beds in the McMurray Formation in close proximity to …
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creator: Susanne W. Fietz
creator: Jim L. Crowley
creator: James A. MacEachern
creator: Shahin E. Dashtgard
creator: H. Dan Gibson
rights: Copyright (c) 2023 Susanne W. Fietz, Jim L. Crowley, James A. MacEachern, Shahin E. Dashtgard, H. Dan Gibson https://creativecommons.org/licenses/by/4.0
date: 2023-11-08
publication date: 2023-11-08
doi: 10.57035/journals/sdk.2023.e11.1131

Constraining the formation conditions of modern pisoids at Ore Lake, Michigan
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description: Large concentrically laminated carbonate grains (here referred to as pisoids) have been observed sporadically throughout the geological record and in modern environments. Explanations for how these grains form have varied widely in different settings, although microbial effects are often involved. In Ore Lake, a ~1 km2 flow-through lake in southeast Michigan, one to four centimeter oblong calcite pisoids are observed in both lake bottom shallows and mounded as a small spit near the primary outflow. In section mm-scale light and more porous along with and dark and more dense concentric laminations are apparent. Here we use field observations, petrography, water chemistry, and stable isotopes to understand their formation. Measurements of pisoid calcite δ18O and lake water δ18O indicate that precipitation occurs in waters between roughly 19 – 28°C. These warm temperatures imply that pisoid growth happens almost entirely within the summer, contrary to prior work that suggested wintertime precipitation was important. Pisoid δ18O values largely overlap with coexisting lake bivalve values, suggesting that pisoid precipitation is in equilibrium. In contrast, pisoid δ13C is as much as 8 ‰ more positive than bivalve δ13C due to photosynthetic effects. We propose that the laminations in these pisoids arise from different rates of formation within the warm months, rather than large seasonal differences. A decline in lake alkalinity beginning in late spring likely coincides with more rapid growth, with slower growth mediated by cyanobacteria continuing through the summer. This range of observations enables the use of Ore Lake as a potential model for understanding pisoid formation throughout the geological record.
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creator: Ryleigh Landstra
creator: Ian Winkelstern
rights: Copyright (c) 2023 Ryleigh Landstra, Ian Winkelstern https://creativecommons.org/licenses/by/4.0
date: 2023-11-27
publication date: 2023-11-27
doi: 10.57035/journals/sdk.2023.e11.1179

New insights into the early Bajocian (Middle Jurassic) carbon cycle perturbation
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description: Mesozoic strata record numerous negative and positive carbon isotope excursions (CIEs). The Middle Jurassic records a negative ~0.5 ‰ CIE at the Aalenian-Bajocian boundary followed by a positive ~1.5 ‰ CIE covering the entire early Bajocian. Although these CIEs are recorded in northern and southwestern Tethys and may reflect perturbations of the global carbon cycle, they remain poorly investigated. In this study, we present new geochemical and sedimentological data from the Chaudon-Norante section in France and Murtinheira section in Portugal to better constrain the origin of the lower Bajocian CIEs. Associated with the previously published carbon isotopic composition of bulk carbonate (δ13Cbulk carbonate) we provide new carbon isotopic composition of bulk organic matter (δ13Corg) records, as well as total phosphorus content, phosphorus accumulation rates (AR), and CaCO3 and organic matter data. In contrast with previous interpretations, our results show no evidence of a carbonate production crisis during the early Bajocian. A slight increase in siliciclastic and phosphorus AR would argue for oceanic fertilization but without a parallel increase in organic matter AR. The obtained stratigraphic δ13Cbulk carbonate vs. δ13Corg patterns are distinctive and mimic previous box modeling results simulating an increase in productivity forced by higher phosphorus rates from riverine and weathered-carbon input burial. The subsequent organic carbon burial produced counter-greenhouse conditions, which in turn produced a cooling by CO2 uptake. Our results indicate that the lower Bajocian event shows several similarities with the late Valanginian positive CIE (also known as the Weissert event). An accurate comparison of both events may help for a better understanding of the origin and consequence of such carbon cycle perturbations.
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creator: Baptiste Suchéras-Marx
creator: Guillaume Suan
creator: Fabienne Giraud
creator: Emanuela Mattioli
creator: Hassan M. Khozyem
creator: Jean-Charles Mazur
creator: Alicia Fantasia
creator: Jorge E. Spangenberg
creator: Thierry Adatte
rights: Copyright (c) 2023 Baptiste Suchéras-Marx, Guillaume Suan, Fabienne Giraud, Emanuela Mattioli, Hassan M. Khozyem, Jean-Charles Mazur, Alicia Fantasia, Jorge E. Spangenberg, Thierry Adatte https://creativecommons.org/licenses/by/4.0
date: 2023-11-27
publication date: 2023-11-27
doi: 10.57035/journals/sdk.2023.e11.1195

Sand dune migration and flux into the lower Helmand and Arghandab valleys
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description: In the Helmand/Sistan basin in south-west Afghanistan, aeolian sediment movement impacts the environment, irrigation canals, agriculture, and fluvial systems. The migration of large sand dunes into the Helmand and Arghandab rivers has a significant impact on the water resources providing livelihood for over three million people. A first step toward mitigating these impacts is to better understand sand dune migration. In this study, dune celerity and flux into the fluvial system are measured using PlanetScope Visual Ortho Scene satellite imagery. Two different time periods were used to quantify flux in five study sites of dune fields along 100 km of the Helmand River and 150 km of the Arghandab and Dori rivers. Results show diverse sand dune celerities with the fastest barchan dune movement south of Zaranj city. Sand dune celerity on the Helmand River right bank in the direction of flow is estimated to vary between 6.2 m/year to 103.1 m/year. The highest unit flux values of 250 m3/m/year occur in the lower Helmand basin. Much lower dune celerity values between 0.2 m/year to 2.9 m/year are calculated for the dune field on the left bank of the Arghandab and Dori rivers. The study also identifies the sensitive locations on the right bank of Helmand River in lower Helmand that may be used to plan sand dune stabilization measures such as mulching and Haloxylon species plantation that have been extensively practiced in the region.
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creator: Najibullah Sadid
rights: Copyright (c) 2023 Najibullah Sadid https://creativecommons.org/licenses/by/4.0
date: 2024-01-16
publication date: 2024-01-16
doi: 10.57035/journals/sdk.2024.e21.1085