Preprints
Filtering by Subject: Geomorphology
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) [...]
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 [...]
Prediction of wave ripple characteristics using genetic programming
Published: 2018-01-21
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
We integrate published data sets of field and laboratory experiments of wave ripples and use genetic programming, a machine learning paradigm, in an attempt to develop a universal equilibrium predictor for ripple wavelength, height, and steepness. We train our genetic programming algorithm with data selected using a maximum dissimilarity selection routine. Thanks to this selection algorithm we [...]
Relict topography within the Hangay Mountains in central Mongolia: Quantifying long-term exhumation and relief change in an old landscape
Published: 2018-01-14
Subjects: Earth Sciences, Geochemistry, Geology, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure
The Hangay Mountains are a high-elevation, low-relief landscape within the greater Mongolian Plateau of central Asia. New bedrock apatite (U-Th)/He single-grain ages from the Hangay span ~70 to 200 Ma, with a mean of 122.7 ± 24.0 Ma (2σ). Detrital apatite samples from the Selenga and Orkhon Rivers, north of the mountains, yield dominant (U-Th)/He age populations of ~115 to 130 Ma, as well as an [...]
Climate-driven unsteady denudation and sediment flux in a high-relief unglaciated catchment-fan using 26Al and 10Be: Panamint Valley, California
Published: 2018-01-13
Subjects: Earth Sciences, Geochemistry, Geology, Geomorphology, Physical Sciences and Mathematics, Sedimentology
Environmental changes within erosional catchments of sediment routing systems are predicted to modulate sediment transfer dynamics. However, empirical and numerical models that predict such phenomena are difficult to test in natural systems over multi-millennial timescales. Tectonic boundary conditions and climate history in the Panamint Range, California, are relatively well-constrained by [...]
Exploring carbonate reef flat hydrodynamics and potential formation and growth mechanisms for motu
Published: 2018-01-11
Subjects: Earth Sciences, Geomorphology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Atolls, which develop as reef-building coral platforms extend to near sea level, typically consist of a shallow reef flat encircling a central lagoon. Often, sub-aerial islets, known as motu or reef islands, consisting of sand, gravel, and coral detritus, can be found perched on the reef flat. Here, we use hydrodynamic numerical modeling (XBeach) to better understand the role of waves and [...]
The effect of meteoric phreatic diagenesis and spring sapping on the formation of submarine collapse structures in the Biak Basin, Eastern Indonesia
Published: 2018-01-11
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics
The islands of Biak and Supiori, situated in the Bird’s Head region of New Guinea, comprise predominantly Neogene age carbonate units that extend offshore into the adjacent Biak Basin. Unusual geomorphologic features including pockmarks, headless canyons and semi-circular collapse structures identified in multibeam bathymetric imagery occur on the southern margin of the Biak Basin. These [...]
Estimating regional flood discharge during Palaeocene-Eocene global warming (submitted)
Published: 2018-01-04
Subjects: Climate, Earth Sciences, Environmental Sciences, Geology, Geomorphology, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Among the most urgent challenges in future climate change scenarios is accurately predicting the magnitude at which precipitation extremes will intensify. Analogous changes have been reported for an episode of millennial scale 5°C warming termed the Palaeocene-Eocene Thermal Maximum (PETM; 56 Ma), providing independent constraints on hydrological response to global warming. However, quantifying [...]
Exogenic forcing and autogenic processes on continental divide location and mobility -- preprint
Published: 2017-12-21
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Sedimentology
The position and mobility of drainage divides is an expression of exogenic landscape forcing and autogenic channel network processes integrated across a range of scales. At the large scale, represented by major rivers and continental drainage divides, the organization of drainage patterns and divide migration reflects the long-wavelength gradients of the topography, which are exogenically [...]