scholarly journals How do basin margins record long-term tectonic and climatic changes?

Geology ◽  
2020 ◽  
Vol 48 (9) ◽  
pp. 893-897
Author(s):  
Jinyu Zhang ◽  
Zoltán Sylvester ◽  
Jacob Covault
Keyword(s):  
Sea Level ◽  
Numerical Models ◽  
Source Area ◽  
Climatic Changes ◽  
Steady States ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Continental Scale ◽  
Sediment Routing ◽  
Basin Margin

Abstract A long-standing goal of sedimentary geoscience is to understand how tectonic and climatic changes are reflected in basin fill. Here, we use 14 numerical models of continental-scale sediment-routing systems spanning millions of years to investigate the responses of sediment supply and basin sedimentation to changes in uplift and precipitation in the source area. We also investigate the extent to which these signals can be altered by relative sea level (the sum of subsidence and eustasy). In cases of constant relative sea level, sediment supply and margin progradation have similar responses because nearly all of the sediment is transported beyond the coastal plain and continental shelf to the basin margin. Thus, margin progradation can be used as a proxy for sediment supply. However, changes in uplift and precipitation result in different erosional patterns in the source area and different basin-margin depositional patterns. Changes in uplift result in gradual (over several million years) adjustment to new steady states of source-area erosion and margin progradation, whereas changes in precipitation result in abrupt changes in erosion and progradation followed by a return to the initial steady states. In cases of changing relative sea level, sediment storage on the shelf attenuates signals of uplift, but signals of precipitation change can be interpreted in the basin-margin record because climate-induced sediment supply changes are large enough to influence margin progradation. Understanding the relationship between sediment supply and basin-margin progradation, and their linked responses to forcings, improves our ability to interpret signals of environmental change in the stratigraphic record.

Feasibility of sedimentation strategies for the Mekong delta to counterbalance relative sea-level rise

2021 ◽  
Author(s):  
Frances E. Dunn ◽  
Philip S. J. Minderhoud
Keyword(s):  
Land Use ◽  
Sea Level Rise ◽  
Sea Level ◽  
Mekong Delta ◽  
Sediment Deposition ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Relative Sea Level ◽  
Fluvial Sediment ◽  
Relative Sea Level Rise

<p>As one of the largest deltas in the world, the Mekong delta is home to over 17 million people and supports internationally important agriculture. Recently deposited sediment compacts and causes subsidence in deltas, so they require regular sediment input to maintain elevation relative to sea level. These processes are complicated by human activities, which prevent sediment deposition indirectly through reducing fluvial sediment supply and directly through the construction of flood defence infrastructure on deltas, impeding floods which deliver sediment to the land. Additionally, anthropogenic activities increase the rate of subsidence through the extraction of groundwater and other land-use practices.</p><p>This research shows the potential for fluvial sediment delivery to compensate for sea-level rise and subsidence in the Mekong delta over the 21st century. We use detailed elevation data and subsidence scenarios in combination with regional sea-level rise and fluvial sediment flux projections to quantify the potential for maintaining elevation relative to sea level in the Mekong delta. We present four examples of localised sedimentation scenarios in specific areas, for which we quantified the potential effectiveness of fluvial sediment deposition for offsetting relative sea-level rise. The presented sediment-based adaptation strategies are complicated by existing land use, therefore a change in water and sediment management is required to effectively use natural resources and employ these adaptation methods. The presented approach could be an exemplar to assess sedimentation strategy feasibility in other delta systems worldwide that are under threat from sea-level rise.</p>

scholarly journals Fluvial Sediment Supply and Relative Sea-Level Rise

2019 ◽  
pp. 103-126
Author(s):  
Stephen E. Darby ◽  
Kwasi Appeaning Addo ◽  
Sugata Hazra ◽  
Md. Munsur Rahman ◽  
Robert J. Nicholls
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Fluvial Sediment ◽  
Relative Sea Level Rise

scholarly journals Data-Driven, Multi-Model Workflow Suggests Strong Influence from Hurricanes on the Generation of Turbidity Currents in the Gulf of Mexico

2020 ◽  
Vol 8 (8) ◽  
pp. 586
Author(s):  
Courtney Harris ◽  
Jaia Syvitski ◽  
H.G. Arango ◽  
E.H. Meiburg ◽  
Sagy Cohen ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Numerical Models ◽  
Ocean Dynamics ◽  
Turbidity Currents ◽  
Regional Ocean Modeling System ◽  
Transport Pathway ◽  
Seabed Sediment ◽  
Continental Scale ◽  
Sediment Routing

Turbidity currents deliver sediment rapidly from the continental shelf to the slope and beyond; and can be triggered by processes such as shelf resuspension during oceanic storms; mass failure of slope deposits due to sediment- and wave-pressure loadings; and localized events that grow into sustained currents via self-amplifying ignition. Because these operate over multiple spatial and temporal scales, ranging from the eddy-scale to continental-scale; coupled numerical models that represent the full transport pathway have proved elusive though individual models have been developed to describe each of these processes. Toward a more holistic tool, a numerical workflow was developed to address pathways for sediment routing from terrestrial and coastal sources, across the continental shelf and ultimately down continental slope canyons of the northern Gulf of Mexico, where offshore infrastructure is susceptible to damage by turbidity currents. Workflow components included: (1) a calibrated simulator for fluvial discharge (Water Balance Model - Sediment; WBMsed); (2) domain grids for seabed sediment textures (dbSEABED); bathymetry, and channelization; (3) a simulator for ocean dynamics and resuspension (the Regional Ocean Modeling System; ROMS); (4) A simulator (HurriSlip) of seafloor failure and flow ignition; and (5) A Reynolds-averaged Navier–Stokes (RANS) turbidity current model (TURBINS). Model simulations explored physical oceanic conditions that might generate turbidity currents, and allowed the workflow to be tested for a year that included two hurricanes. Results showed that extreme storms were especially effective at delivering sediment from coastal source areas to the deep sea, at timescales that ranged from individual wave events (~hours), to the settling lag of fine sediment (~days).

scholarly journals Lower Badenian coarse-grained Gilbert deltas in the southern margin of the Western Carpathian Foredeep basin

2018 ◽  
Vol 69 (1) ◽  
pp. 89-113 ◽  
Author(s):  
Slavomír Nehyba
Keyword(s):  
Sea Level ◽  
Foreland Basin ◽  
Sediment Supply ◽  
Coarse Grained ◽  
Basal Surface ◽  
Relative Sea Level ◽  
Sediment Delivery ◽  
Southern Margin ◽  
Stratigraphic Architecture ◽  
Carpathian Foredeep

AbstractTwo coarse-grained Gilbert-type deltas in the Lower Badenian deposits along the southern margin of the Western Carpathian Foredeep (peripheral foreland basin) were newly interpreted. Facies characterizing a range of depositional processes are assigned to four facies associations — topset, foreset, bottomset and offshore marine pelagic deposits. The evidence of Gilbert deltas within open marine deposits reflects the formation of a basin with relatively steep margins connected with a relative sea level fall, erosion and incision. Formation, progradation and aggradation of the thick coarse-grained Gilbert delta piles generally indicate a dramatic increase of sediment supply from the hinterland, followed by both relatively continuous sediment delivery and an increase in accommodation space. Deltaic deposition is terminated by relatively rapid and extended drowning and is explained as a transgressive event. The lower Gilbert delta was significantly larger, more areally extended and reveals a more complicated stratigraphic architecture than the upper one. Its basal surface represents a sequence boundary and occurs around the Karpatian/Badenian stratigraphic limit. Two coeval deltaic branches were recognized in the lower delta with partly different stratigraphic arrangements. This different stratigraphic architecture is mostly explained by variations in the sediment delivery and /or predisposed paleotopography and paleobathymetry of the basin floor. The upper delta was recognized only in a restricted area. Its basal surface represents a sequence boundary probably reflecting a higher order cycle of a relative sea level rise and fall within the Lower Badenian. Evidence of two laterally and stratigraphically separated coarse-grained Gilbert deltas indicates two regional/basin wide transgressive/regressive cycles, but not necessarily of the same order. Provenance analysis reveals similar sources of both deltas. Several partial source areas were identified (Mesozoic carbonates of the Northern Calcareous Alps and the Western Carpathians, crystalline rocks of the eastern margin of the Bohemian Massif, older sedimentary infill of the Carpathian Foredeep and/or the North Alpine Foreland Basin, sedimentary rocks of the Western Carpathian/Alpine Flysch Zone).

scholarly journals OSL-SAR dating of sediments from Brazilian aeolian system: Dama Branca, Rio de Janeiro, morphodynamic study

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Lucas Sátiro Do Carmo
Keyword(s):  
Sea Level ◽  
Rio De Janeiro ◽  
Climatic Changes ◽  
Coastal Dune ◽  
Optically Stimulated Luminescence ◽  
Relative Sea Level ◽  
Dune Field ◽  
Wind Action ◽  
Aeolian Systems ◽  
The Town

It has been reported that the formation and stabilization of coastal dune fields in Brazil have a dependence on the climatic changes, Relative Sea Level (RSL) variations, etc. In this work, a dune field known as “Dama Branca”, located in the town of Cabo Frio, Rio de Janeiro, has been studied to understand its mobility, formation and stabilization. Dating by trapped charge dating techniques as Optically Stimulated Luminescence (OSL) using the Single Aliquot Regenerative protocol (SAR), helps us to understand the formation and dynamics of aeolian systems in Brazil. Samples from two positions; DB and 2DB, were collected from different heights and points for dating. The results obtained by OSL-SAR showed that ages decrease as the height from the dune base increase and older samples are found in deeper horizontal positions. The ages from the base of the studied dunes indicated that its stabilization occurred during the recess of the sea level and that erosion caused by the wind action is revealing an old generation of this dune filed.

scholarly journals Sedimentation and Survival of the Mekong Delta: A Case Study of Decreased Sediment Supply and Accelerating Rates of Relative Sea Level Rise

Oceanography ◽  
2017 ◽  
Vol 30 (3) ◽  
pp. 98-109 ◽  
Author(s):  
Mead Allison ◽  
◽  
Charles Nittrouer ◽  
Andrea Ogston ◽  
Julia Mullarney ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Mekong Delta ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Relative Sea Level Rise

The interplay between relative sea-level rise and sediment supply at the distal part of the Nile littoral cell

The Holocene ◽  
2015 ◽  
Vol 26 (2) ◽  
pp. 248-264 ◽  
Author(s):  
Hadar Elyashiv ◽  
Revital Bookman ◽  
Dov Zviely ◽  
Simona Avnaim-Katav ◽  
Amir Sandler ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Distal Part ◽  
Sediment Supply ◽  
Relative Sea Level ◽  
Littoral Cell ◽  
Relative Sea Level Rise

scholarly journals Boulder-strewn flats in a high-latitude macrotidal embayment, Baffin Island: geomorphology, formation, and future stability

2021 ◽  
Author(s):  
Scott Vincent Hatcher ◽  
Donald L. Forbes ◽  
Gavin K. Manson
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
High Latitude ◽  
Open Water ◽  
Tidal Flats ◽  
Sediment Supply ◽  
Tidal Range ◽  
Baffin Island ◽  
Relative Sea Level ◽  
Sand And Gravel

Tidal flats are widely distributed on high-latitude coasts, where sea ice processes have been invoked to explain the abundance and distribution of boulders. This study documents the surface morphology and sediment dynamics of a low-Arctic macrotidal system, the boulder-rich tidal flats of Koojesse Inlet, fronting the Nunavut capital, Iqaluit, on Baffin Island. This is a region of postglacial isostatic uplift and forced regression, with raised littoral, deltaic, and glaciomarine deposits. The spring-tidal range is 11.1 m and sea ice cover lasts roughly 9 months of the year. The extensive intertidal flats are up to 1 km wide, with a veneer of sand and gravel (including large boulders) resting on an erosional unconformity truncating the underlying glaciomarine mud, forming a terrace within the present tidal range. Over a three-year study, no consistent pattern of erosion or deposition was evident. Over a longer time scale, the concave hypsometry, low sediment supply, slight ebb-dominance of weak tidal currents, abrasion by wave-entrained sand, ebb-oriented ripples formed under subaerial drainage, and slumps on the terrace flanks are consistent with seaward hydraulic and gravitational sediment transport. These processes may be of greater importance than shoreward ice transport. This study underlines the importance of relict glaciomarine deposits, postglacial uplift, and falling relative sea level in the erosional development of these high-latitude tidal flats. Relative sea-level projections for Iqaluit are ambiguous, but a switch to rising sea level, if it occurs, combined with more open water and wave energy, could alter the foreshore dynamics of the system.

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