Preprints
Filtering by Subject: Sedimentology
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: 2018-06-15
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 [...]
Identifying causes of ground-penetrating radar reflections using time-domain reflectometry and sedimentological analyses
Published: 2018-05-07
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology
Ground-penetrating radar (GPR) is a geophysical technique widely used to study the shallow subsurface and identify various sediment features that reflect electromagnetic waves. However, little is known about the exact cause of GPR reflections because few studies have coupled wave theory to petrophysical data. In this study, a 100- and 200-MHz GPR survey was conducted on aeolian deposits in a [...]
Bedform migration in a mixed sand and cohesive clay intertidal environment and implications for bed material transport predictions
Published: 2018-05-03
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
Many coastal and estuarine environments are dominated by mixtures of non-cohesive sand and cohesive mud. The migration rate of bedforms, such as ripples and dunes, in these environments is important in determining bed material transport rates to inform and assess numerical models of sediment transport and geomorphology. However, these models tend to ignore parameters describing the physical and [...]
Sedimentary Architecture of an Ancient Linear Megadune (Barremian, Neuquén Basin): Insights into the Long-Term Development and Evolution of Aeolian Linear Bedforms
Published: 2018-04-21
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
Linear aeolian bedforms are the most abundant bedform type in modern Earth sand seas and are very common in our Solar System. Despite their abundance, the long-term development of these bedforms and its impact upon the resulting sedimentary architecture in the geological record is still poorly understood. The aims of this paper are to study the exposed record of an ancient linear megadune in [...]
Using climate to relate water-discharge and area in modern and ancient catchments
Published: 2018-04-13
Subjects: Earth Sciences, Hydrology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Models relating sediment-supply to catchment-properties are important in order to use the geological record to deduce landscape evolution and the interplay between tectonics and climate. Water-discharge (Qw) is an important factor in the widely used BQwART-model of Syvitski and Milliman (2007), which relates sediment load to a set of measureable catchment parameters. Although many of the factors [...]
Resolving the era of river-forming climates on Mars using stratigraphic logs of river-deposit dimensions
Published: 2018-03-10
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
River deposits are one of the main lines of evidence that tell us that Mars once had a climate different from today, and so changes in river deposits with time tell us something about how Mars climate changed with time. In this study, we focus in on one sedimentary basin – Aeolis Dorsa – which contains an exceptionally high number of exceptionally well-preserved river deposits that appear to have [...]
Is fine sediment in sandy riverbed deposits a proxy for paleo-sediment supply?
Published: 2018-03-04
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
The amount of silt and clay supplied to rivers can be a primary control on the form and dynamics of channel networks, and it affects the distribution and interconnectedness of buried fluvial reservoirs. Despite its importance, it is difficult to reconstruct how much fine sediment was supplied to ancient rivers. The presence of silt and clay accumulations in sandy river deposits is often [...]
Redefining ‘Clean’ Sand By Integrating Field And Laboratory Data On Mixed Sand–Clay–EPS Rippled-Bed Transport
Published: 2018-03-03
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
The shape and size of sedimentary bedforms play a key role in the reconstruction of sedimentary processes in modern and ancient environments. Recent laboratory experiments have shown that bedforms in mixed sand–clay develop at a slower rate and often have smaller heights and lengths than equivalent bedforms in pure sand. This is generally attributed to cohesive forces that can be of physical [...]
A faithful record of channel mouth bifurcation angles in river delta stratigraphy on Earth and Mars
Published: 2018-03-02
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Which geomorphologic features of sedimentary systems persist into the stratigraphic record? In modern river deltas, channel mouth bifurcation angles have been shown to be consistent with network growth in a Laplacian flow field proximal to the channel margins. This results in a characteristic bifurcation angle of 72 . However, the persistence of this formative angle through channel evolution and [...]
What caused Earths largest mass extinction event? New evidence from the Permian-Triassic boundary in northeastern Utah
Published: 2018-02-26
Subjects: Biogeochemistry, Biology, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Indicators and Impact Assessment, Environmental Sciences, Geology, Life Sciences, Paleobiology, Paleontology, Physical Sciences and Mathematics, Sedimentology
The discovery of a Permian-Triassic boundary section in northeastern Utah reveals a detailed record of events that led to one of the greatest mass extinctions on the planet. From 83% to 97% of the species living on the planet went extinct during this relatively short interval of geological time, which defines the major geological boundary between the Paleozoic and Mesozoic Eras. The cause and [...]