Preprints
Filtering by Subject: Sedimentology
Using bar preservation to constrain reworking in channel-dominated fluvial stratigraphy
Published: 2018-08-16
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Fluvial deposits comprising more than 80% channel facies are often thought to have accumulated during intervals of relatively slow subsidence in sedimentary basins. This interpretation stems from the conceptual model that migrating and avulsing rivers rework their own deposits during times of limited accommodation creation, preferentially removing and bypassing fine floodplain deposits. [...]
Quantification of the Bed-scale Architecture of Submarine Depositional Environments and Application to Lobe Deposits of the Point Loma Formation, California
Published: 2018-08-11
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
As of August 2018, this work is in review in "The Depositional Record", a journal from the IAS (International Association of Sedimentologists) Submarine-fan deposits form the largest sediment accumulations on Earth and host significant reservoirs for hydrocarbons. While many studies of ancient fan deposits qualitatively [...]
Characterisation of submarine depression trails driven by upslope migrating cyclic steps: Insights from the Ceará Basin (Brazil)
Published: 2018-08-08
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Circular to elliptical topographic depressions, isolated or organized in trails, have been observed on the modern seabed in different contexts and water depths. Such features have been alternatively interpreted as pockmarks generated by fluid flow, as sediment waves generated by turbidity currents, or as a combination of both processes. In the latter case, the dip of the slope has been [...]
New evidence for a major late Quaternary submarine landslide on the external western levee of Laurentian Fan
Published: 2018-08-07
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
The Laurentian Fan is one of the largest submarine fans on the western margin of the North Atlantic. Recently acquired high-resolution multibeam bathymetric data (60 m horizontal resolution) reveal a major mass transport deposit (MTD) on the Western Levee of Western Valley (WLWV), covering >14 000 km2 in water depths from 3900 m to >5000 m. Typical submarine landslide features are observed [...]
Shark-fins: overturned patterns linked to shear instabilities at the flow-bed boundary. Examples from the deposits of the 2006 pyroclastic currents at Tungurahua volcano (Ecuador)
Published: 2018-08-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Volcanology
Enigmatic structures grouped under the term "shark-fins" are documented in laminated deposits of pyroclastic currents. They consist of an overturning of a few laminae on a decimeter scale, forming overbent "flames" or convolute laminae, which occur in successive, periodic patterns. More than 200 shark-fins were investigated and measured in cross-laminated deposits from the 2006 pyroclastic [...]
Pyroclastic dune bedforms: macroscale structures and lateral variations. Examples from the 2006 pyroclastic currents at Tungurahua (Ecuador)
Published: 2018-08-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Volcanology
Pyroclastic currents are catastrophic flows of gas and particles triggered by explosive volcanic eruptions. For much of their dynamics, they behave as particulate density currents and share similarities with turbidity currents. Pyroclastic currents occasionally deposit dune bedforms with peculiar lamination patterns, from what is thought to represent the dilute low concentration and [...]
Tectonic and oceanographic process interactions archived in the Late Cretaceous to Present deep-marine stratigraphy on the Exmouth Plateau, offshore NW Australia
Published: 2018-07-11
Subjects: Earth Sciences, Engineering, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure
Deep-marine deposits provide a valuable archive of process interactions between sediment gravity flows, pelagic sedimentation, and thermo-haline bottom-currents. Stratigraphic successions can also record plate-scale tectonic processes (e.g. continental breakup and shortening) that impact long-term ocean circulation patterns, including changes in climate and biodiversity. One such setting is the [...]
Micromorphological report of Hof ter Coign
Published: 2018-06-28
Subjects: Agriculture, Earth Sciences, Education, Engineering, Environmental Sciences, Environmental Studies, Geography, Geology, Life Sciences, Physical and Environmental Geography, Physical Sciences and Mathematics, Sedimentology, Social and Behavioral Sciences, Soil Science
Micromorphological report of the Hof ter Coign site (Belgium)
Constructional process of relatively high-relief crescent-shaped bedforms in submarine channels by gravelly sand-laden flows: analysis of the ancient case study of the Guredin palaeo-bedforms
Published: 2018-06-27
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
The channel-fills of the Miocene Alikayasi submarine channel system in the south of Turkey offer an extraordinary opportunity to improve our understanding of the physical properties of gravity-driven gravelly sand-laden flows and their resulting deposits on the seafloor. This study describes and analyses a particular area of an ancient channel-fill that is interpreted as the preserved deposits of [...]
Palaeolithic artefact deposits at Wadi Dabsa, Saudi Arabia; a multi-scalar geoarchaeological approach to building an interpretative framework
Published: 2018-06-21
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Surface artefacts dominate the archaeological record of arid landscapes, particularly the Saharo-Arabian belt, a pivotal region in dispersals out of Africa. Discarded by hominins, these artefacts are key to understanding past landscape use and dispersals, yet behavioural interpretation of present-day artefact distributions cannot be carried out without understanding how geomorphological processes [...]
A fossiliferous spherule-rich bed at the Cretaceous-Paleogene (K-Pg) boundary in Mississippi, USA: implications for the K-Pg mass extinction event in the MS Embayment and Eastern Gulf Coastal Plain
Published: 2018-06-14
Subjects: Astrophysics and Astronomy, Earth Sciences, Geochemistry, Geology, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology
We describe an outcrop of the Cretaceous–Paleogene (K–Pg) boundary exposed due to construction near New Albany, Union County, Mississippi. It consists of the Owl Creek Formation and overlying Clayton Formation. The Owl Creek Formation is rich in the ammonites Discoscaphites iris and Eubaculites carinatus, which, along with biostratigraphically important dinoflagellate cysts and calcareous [...]
Detrital Zircons from the Amazon river-to-fan system reveal base level controls on land-to-sea sediment transfer
Published: 2018-06-06
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology
Large tropical sediment routing systems have relatively stable output fluxes over observable timescales. However, the functioning of sediment transfer in these systems across Pleistocene climate and sea-level fluctuations is not well documented. Here, we use new U-Pb detrital zircon (DZ) geochronology from the Pleistocene Amazon submarine fan (n=1,362 grains) to investigate provenance signatures [...]
The effects of differential compaction on clinothem geometries and shelf-edge trajectories
Published: 2018-05-23
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
The geometry of basin margin strata documents changes in water depth, slope steepness, and sedimentary facies distributions. Their stacking patterns are widely used to define shelf-edge trajectories, which reflect long-term variations in sediment supply and relative sea level change. Here, we present a new method to reconstruct the geometries and trajectories of clinoform-bearing basinmargin [...]
Dynamics of settling-driven convection beneath a sediment laden buoyant overflow: implications for the length-scale of deposition in lakes and the coastal ocean
Published: 2018-05-16
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
The length-scale of deposition beneath a buoyant sediment-laden river plume can be strongly influenced by enhanced settling-driven convection, and is directly related to the horizontal velocity of the plume and a sedimentation time-scale. In our experiments, a buoyant plume of fresh water and sediment spreads over a denser saline layer. The speed of the plume increases with the net density [...]
On the timing and nature of the multiple phases of slope instability on eastern Rockall Bank, Northeast Atlantic
Published: 2018-05-11
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
One of the most challenging tasks when studying large submarine landslides is determining whether the landslide was initiated as a single large event, a chain of events closely spaced in time or multiple events separated by long periods of time as all have implications in risk assessments. In this study we combine new multichannel seismic profiles and new sediment cores with bathymetric data to [...]