Preprints
Filtering by Subject: Stratigraphy
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 [...]
Crustal strain in the Marmara pull-apart region associated with the propagation process of the North Anatolian Fault
Published: 2018-04-11
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Stratigraphy, Tectonics and Structure
Propagation processes of plate-scale faults through continental lithosphere are poorly documented. The North Anatolian fault (NAF) is a continental right-lateral transform with striking evidence for propagation processes in the Marmara Sea pull-apart region. Earlier work [Armijo et al., 1999] suggests that in the Dardanelles, where the principal, northern branch of that fault (NNAF) enters into [...]
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 [...]
A faithful record of channel mouth bifurcation angles in river delta stratigraphy on Earth and Mars
Published: 2018-03-01
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 [...]
Volume And Recurrence of Submarine-Fan-Building Turbidity Currents
Published: 2018-01-28
Subjects: Analysis, Applied Mathematics, Earth Sciences, Geology, Geomorphology, Mathematics, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
(now published in "The Depositional Record") Submarine fans are archives of Earth-surface processes and change, recording information about the turbidity currents that construct and sculpt them. The volume and recurrence of turbidity currents are of great interest for geohazard assessment, source-to-sink modeling, and hydrocarbon reservoir characterization. Yet, such dynamics are poorly [...]
Facies architecture of submarine channel deposits on the western Niger Delta slope: Implications for grain-size and density stratification in turbidity currents
Published: 2018-01-28
Subjects: Earth Sciences, Geology, Geomorphology, Mathematics, Oceanography and Atmospheric Sciences and Meteorology, Other Mathematics, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
High-resolution bathymetry, seismic reflection, and piston core data from a submarine channel on the western Niger Delta slope demonstrate that thick, coarse-grained, amalgamated sands in the channel thalweg/axis transition to thin, fine-grained, bedded sands and muds in the channel margin. Radiocarbon ages indicate that axis and margin deposits are coeval. Core data show that bed thickness, [...]
High Resolution, Millennial-Scale Patterns of Bed Compensation on a Sand-Rich Intraslope Submarine Fan, Western Niger Delta Slope
Published: 2018-01-28
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Near-seafloor core and seismic-reflection data from the western Niger Delta continental slope document the facies, architecture, and evolution of submarine channel and intraslope submarine fan deposits. The submarine channel enters an 8 km long x 8 km wide intraslope basin, where more than 100 m of deposits form an intraslope submarine fan. Lobe deposits in the intraslope submarine fan show no [...]
Comparing submarine and fluvial channel kinematics: Implications for stratigraphic architecture
Published: 2018-01-28
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Submarine and fluvial channels exhibit qualitatively similar geomorphic patterns, yet produce very different stratigraphic records. We reconcile these seemingly contradictory observations by focusing on the channel-belt scale and quantifying the time-integrated stratigraphic record of the belt as a function of (1) the geometric scale and (2) the trajectory of the geomorphic channel, applying the [...]
Rapid Adjustment of Submarine Channel Architecture to Changes in Sediment Supply
Published: 2018-01-28
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Changes in sediment supply and caliber during the last ~130 ka have resulted in a complex architectural evolution of the Y channel system on the western Niger Delta slope. This evolution consists of four phases, each with documented or inferred changes in sediment supply. Phase 1 flows created wide (1,000 m), low-sinuosity (1.1) channel forms with lateral migration and little to no aggradation. [...]
Climbing Ripple Successions in Turbidite Systems: Depositional Environments, Sedimentation Rates, and Accumulation Times
Published: 2018-01-28
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Climbing-ripple cross-lamination (CRCL) is most commonly deposited by turbidity currents when suspended load fallout and bedload transport occur contemporaneously. The angle of ripple climb reflects the ratio of suspended load fallout and bedload sedimentation rates, allowing for the calculation of the flow properties and durations of turbidity currents. Three areas exhibiting thick (> 50 m) [...]
Macrostrat: a platform for geological data integration and deep-time Earth crust research
Published: 2018-01-27
Subjects: Biogeochemistry, Earth Sciences, Geology, Paleobiology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Characterizing the lithology, age, and physical-chemical properties of rocks and sediments in the Earths upper crust is necessary to fully assess energy, water, and mineral resources and to address many fundamental questions in the Earth sciences. Although a large number of geological maps, regional geological syntheses, and sample-based measurements have been produced, there is no openly [...]
Two Fundamentally Different Types of Submarine Canyons Along the Continental Margin of Equatorial Guinea
Published: 2018-01-24
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Most submarine canyons are erosive conduits cut deeply into the world’s continental shelves through which sediment is transported from areas of high coastal sediment supply onto large submarine fans. However, many submarine canyons in areas of low sediment supply do not have associated submarine fans and show significantly different morphologies and depositional processes from those of ‘classic’ [...]
Facies and Architectural Asymmetry in a Conglomerate-Rich Submarine Channel Fill, Cerro Toro Formation, Sierra Del Toro, Magallanes Basin, Chile
Published: 2018-01-24
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Cross-sectional asymmetry is characteristic of sinuous channels, in both fluvial and submarine settings. Less well documented are the facies distributions of asymmetric channels, particularly in submarine settings. Exposures of the axial channel-belt in the Magallanes retro-arc foreland basin on Sierra del Toro represent the fill of a 3.5 km wide, 300 m thick channel complex, here termed the [...]
Salt thickness and composition influence rift structural style, northern North Sea, offshore Norway
Published: 2018-01-24
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy, Tectonics and Structure
‘Salt’ giants are typically halite-dominated, although they invariably contain other evaporite (e.g. anhydrite, bittern salts) and non-evaporite (e.g. carbonate, clastic) rocks. Rheological differences between these rocks mean they impact or respond to rift-related, upper crustal deformation in different ways. Our understanding of basin-scale lithology variations in ancient salt giants, what [...]