scholarly journals Sediment routing from shelf to basin floor in the Quaternary Golo System of Eastern Corsica, France, western Mediterranean Sea

2019 ◽  
Vol 132 (5-6) ◽  
pp. 1217-1234 ◽  
Author(s):  
Michael L. Sweet ◽  
Gwladys T. Gaillot ◽  
Gwenael Jouet ◽  
Tammy M. Rittenour ◽  
Samuel Toucanne ◽  
...  
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
Tectonic Setting ◽  
Hydrocarbon Exploration ◽  
Submarine Canyons ◽  
Deposition Rates ◽  
Submarine Fans ◽  
Sediment Routing ◽  
Basin Scale ◽  
Glacial Periods

Abstract How and when sediment moves from shallow marine to deep-water environments is an important and poorly understood control on basin-scale sediment dispersal patterns, the evolution of continental margins, and hydrocarbon exploration in deep-water basins. The Golo River (Eastern Corsica, France), its delta, canyons, and fans provide a unique opportunity to study sediment routing from source to sink in a relatively compact depositional system. We studied this system using an array of high-frequency seismic data, multi-beam bathymetry, and five cores for lithology and age control. Movement of sediment to deep water was controlled by interactions between the Golo River, the Golo Delta, and shelf-penetrating submarine canyons. Sediment moved to deep water when lobes of the Golo Delta prograded to the heads of these canyons, or when the Golo River itself flowed directly into one of them. Sand accumulated in canyons, deep-water channels, and submarine fans during glacial periods of low sea level, while mud was deposited throughout the slope, in the relatively short reach of leveed-confined channels, and in the mud-rich fringes around the sandy fans. During interglacial periods of high sea level, the basin was blanketed by mud-rich deposits up to 10 m thick interbedded with distinctive carbonate-rich sediments. Deposition rates in the basin ranged from 0.07 m/ka to 0.59 m/ka over the last 450 ka. Mud deposition rates remained relatively constant at ∼0.16 m/ka during all time periods, while sand deposition only happened during glacial periods of low sea level with an average rate of 0.24 m/ka. In addition to sea-level controls on sediment delivery, avulsions of the Golo River and its deltaic lobes preferentially routed sediment down either the North or South Golo canyons. Thus, while the larger, sequence-scale architecture of the basin is controlled by allogenic sea level forcing, millennial-scale autogenic processes operating on the shelf and in deep water shaped the distribution of sand and mud, and the internal geometry of the deltas and submarine fans that they fed. While some aspects of the Golo system are characteristic of steep, tectonically active margins, others such as the nature of connections between rivers and shelf-penetrating submarine canyons are observed in most margins with active submarine fans regardless of their tectonic setting.

How fast do submarine fans grow? Insights from the Quaternary Golo fans, offshore Corsica

Geology ◽  
2021 ◽  
Author(s):  
Michael L. Sweet ◽  
Gwladys T. Gaillot ◽  
Tammy M. Rittenour ◽  
Kathrine Love ◽  
Michael D. Blum
Keyword(s):  
Sea Level ◽  
Time Scales ◽  
River Channels ◽  
Sea Level Changes ◽  
Sand Fraction ◽  
Deposition Rates ◽  
Submarine Channels ◽  
Submarine Fans ◽  
Formation And Evolution ◽  
Glacial Periods

High-resolution seismic, core, and chronological data from the Quaternary Golo deep-sea fans, offshore Corsica, France, give new insights into rates of submarine fan growth. Average vertical deposition rates for units that represent the Late Pleistocene glacial periods are 0.1–0.5 m/k.y. Glacial-age deposits are sand rich; in contrast, post-glacial deposits lack a significant sand fraction and are dominated by carbonate-rich mud. As a result, seismically constrained volumetric rates of deposition for glacial periods with low sea level and a subaerially exposed shelf are ~0.23 km3/k.y., 2×–5× higher than rates during interglacials when sea level is high, the shelf is submerged, and sand is trapped in shallow-marine environments. At millennial time scales, variations in deposition rate reflect climate-driven sea-level changes, autogenic avulsion of river channels that extend across the shelf during low sea level, and autogenic avulsion of submarine channels that shift the locus of deposition laterally. Short-term deposition rates range from 8.6 m/k.y. at proximal portions of submarine fans to 0.4 m/k.y. along the distal fringe. Our data show that submarine fans can be dynamic environments with formation and evolution of levee-confined channels and lobe complexes in 103–104 yr, comparable to the time scales needed to form fluvial channel belts and delta lobes.

Recurrence of turbidity currents on glaciated continental margins: A conceptual model from eastern Canada

2020 ◽  
Vol 90 (10) ◽  
pp. 1305-1321
Author(s):  
Alexandre Normandeau ◽  
D. Calvin Campbell
Keyword(s):  
Conceptual Model ◽  
Sea Level ◽  
Deep Water ◽  
Turbidity Current ◽  
Sediment Supply ◽  
Turbidity Currents ◽  
Continental Margins ◽  
Submarine Canyons ◽  
Eastern Canada ◽  
Current Activity

ABSTRACT Turbidity currents in submarine canyons transport large volumes of sediment and carbon to the deep sea and are known to present a major risk to submarine infrastructure. Understanding the origin, the triggers, the recurrence, and the timing of these events is important for predicting future events and mitigating their impact. Depending on the morphological and latitudinal setting of submarine canyons, different external controls will govern the recurrence of turbidity currents. Here, we assess the recurrence of turbidity currents in shelf-incising submarine canyons off eastern Canada in order to examine the effects of external forcings such as glacier retreat and sea level on the deep-water sedimentary record. We used multibeam bathymetry, sub-bottom profiles, and the analysis of turbidites in sediment cores to infer the triggers of turbidity currents over time and propose a conceptual model for the activity of turbidity currents during glacial retreat. The chronostratigraphy of turbidites shows that turbidity current activity in the glaciated The Gully submarine canyon (eastern Canada) was highest between 24 ka cal BP (LGM) and 17 ka cal BP, with > 100 turbidites per 1,000 yr, when the ice sheet was directly delivering sediment to submarine canyons. As the ice margin retreated, the dominant sediment supply switched to glaciofluvial and then to longshore drift, while RSL remained low. The recurrence of turbidity currents nonetheless decreased drastically to < 10 per 1000 yr during that time, pre-dating the rise in RSL. This timing suggests that the reduction of turbidity-current activity is closely linked to retreating glaciers rather than to sea-level rise, which occurred later. Following the retreat of the ice sheet, sea level rose progressively to drown the shallow banks on the continental shelf, and turbidity currents ceased being active after 13 ka cal BP. In the late Holocene, landslide and concomitant turbidity-current recurrence increased to 1 per 1,000 yrs, with at least four new events recorded in deep water. This study shows that glacial sediment supply and sea level controlled the type of sediment supply to the continental slope, which in turn controlled the triggers of turbidity currents over time and the flushing of sediment to the deep water. By comparing with other glaciated margins, we propose a conceptual model explaining the recurrence of turbidity currents, taking into account RSL change and the position of the ice margin relative to the shelf edge. This conceptual model can help predict turbidity-current activity and offshore geohazards on other ancient and modern glaciated continental margins.

scholarly journals Evolution of the North Horowhenua Coastal Depositional System in Response to Late Pleistocene Sea Level Changes

2021 ◽  
Author(s):  
◽  
Glenn Richard Hughes
Keyword(s):  
Sea Level ◽  
Tectonic Setting ◽  
Sea Level Changes ◽  
Last Interglacial ◽  
Shallow Marine ◽  
Marine Strata ◽  
Valley Fill ◽  
The North ◽  
Glacial Periods ◽  
And Sea Level

<p>The convergent tectonic setting of New Zealand has lead to the development of a series of anticlines and troughs resulting from folding and faulting of basement greywacke in southwest North Island. The most extensive of these is the Kairanga Trough spreading from the Horowhenua to the Manawatu, which lies between the uplifting Tararua Range and subsiding South Wanganui Basin. This trough was a major depocentre for fluvial and shallow marine strata during the Quaternary. By utilising a 280m deep borehole from the Kairanga Trough, this thesis investigates how climate and sea level variations affected sedimentation in the north Horowhenua District.   This borehole has recorded a near continuous record of climate and sea level change for the last 340ka. The lower part of the core is a marine sequence representing progressive infilling of the Kairanga Trough during 5th order (c.100ka) glacioeustatic fluctuations, which consequently produced 4 marine cyclothems. Transgressions and subsequent highstand periods are represented by shallow marine sediment, which were followed by fluvial aggradation during lowstand periods, then marine planation during subsequent transgressions. Cycle 1 developed during OIS 9 (340-300ka). Cycles 2 and 3 both formed during OIS 7 as a result of two closely spaced highstands centred around 245ka (OIS 7c) and 200ka (OIS 7a), which were separated by a period of lower sea level around 225ka (OIS 7b) that produced a disconformity. Cycle 4 formed during the Last Interglacial transgression (OIS 5e) and represents an incised valley fill. Progradation of a coastal strandplain and alluvial plain representing the latter stages of infilling of the Kairanga Trough with coastal and terrigenous sediment during the mid to late Last Interglacial and Glacial Periods is recorded in the sediment composing the top part of the borehole.</p>

Regional implications of structural and eustatic controls in the evolution of submarine fans: an example from the Miocene Adana Basin, southern Turkey

1999 ◽  
Vol 136 (3) ◽  
pp. 311-319 ◽  
Author(s):  
KEMAL GÜRBÜZ
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
Eastern Mediterranean ◽  
Source Area ◽  
Submarine Fans ◽  
The North ◽  
Southern Turkey ◽  
Sea Fan ◽  
Local Tectonics ◽  
Stacking Patterns

Deep-sea fan development is generally thought to be controlled by a combination of changes in sea level, the shape and size of the basin in which the fans are growing, and the nature of the source area. The Early Miocene evolution of the eastern Mediterranean involved significant accumulation of deep-water clastic sediment in which the importance of each of these controlling factors can be evaluated. The deep-water clastic system located in the Adana Basin has been studied in detail. Two contemporaneous, small, radial, sand-rich submarine fans (one in the west and one in the east) exhibiting different scales, fan types and styles of deposition have been recognized within the Cingöz turbidite sequence of the northern Adana Basin in southern Turkey. Sedimentological studies indicate that the fans were controlled externally by tectonics and relative eustatic sea-level fall during late Serravallian time, in combination with the nature of the source area to the north. The internal architectural stacking patterns and external geometry of the two fan systems were strongly affected by the interaction of local tectonics and turbidity current pathways, including a major topographic confinement to the southeast that forced a vertical aggradation of the eastern fan and an east–west elongation of the western fan. This paper describes a classic example of a well-exposed deep-water clastic system where (1) tectonically driven sea-floor topography, (2) syn-sedimentary tectonism and (3) eustatic rise in sea level, are the primary controls on its development.

scholarly journals Evolution of the North Horowhenua Coastal Depositional System in Response to Late Pleistocene Sea Level Changes

2021 ◽  
Author(s):  
◽  
Glenn Richard Hughes
Keyword(s):  
Sea Level ◽  
Tectonic Setting ◽  
Sea Level Changes ◽  
Last Interglacial ◽  
Shallow Marine ◽  
Marine Strata ◽  
Valley Fill ◽  
The North ◽  
Glacial Periods ◽  
And Sea Level

<p>The convergent tectonic setting of New Zealand has lead to the development of a series of anticlines and troughs resulting from folding and faulting of basement greywacke in southwest North Island. The most extensive of these is the Kairanga Trough spreading from the Horowhenua to the Manawatu, which lies between the uplifting Tararua Range and subsiding South Wanganui Basin. This trough was a major depocentre for fluvial and shallow marine strata during the Quaternary. By utilising a 280m deep borehole from the Kairanga Trough, this thesis investigates how climate and sea level variations affected sedimentation in the north Horowhenua District.   This borehole has recorded a near continuous record of climate and sea level change for the last 340ka. The lower part of the core is a marine sequence representing progressive infilling of the Kairanga Trough during 5th order (c.100ka) glacioeustatic fluctuations, which consequently produced 4 marine cyclothems. Transgressions and subsequent highstand periods are represented by shallow marine sediment, which were followed by fluvial aggradation during lowstand periods, then marine planation during subsequent transgressions. Cycle 1 developed during OIS 9 (340-300ka). Cycles 2 and 3 both formed during OIS 7 as a result of two closely spaced highstands centred around 245ka (OIS 7c) and 200ka (OIS 7a), which were separated by a period of lower sea level around 225ka (OIS 7b) that produced a disconformity. Cycle 4 formed during the Last Interglacial transgression (OIS 5e) and represents an incised valley fill. Progradation of a coastal strandplain and alluvial plain representing the latter stages of infilling of the Kairanga Trough with coastal and terrigenous sediment during the mid to late Last Interglacial and Glacial Periods is recorded in the sediment composing the top part of the borehole.</p>

Groins, sand retention, and the future of Southern California’s beaches

Shore & Beach ◽  
2020 ◽  
pp. 14-36
Author(s):  
Gary Griggs ◽  
Kiki Patsch ◽  
Charles Lester ◽  
Ryan Anderson
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Southern California ◽  
Beach Sand ◽  
Submarine Canyons ◽  
Littoral Drift ◽  
Short Supply ◽  
Land Use Decisions ◽  
Coastal Cliffs ◽  
Retention Structures

Beaches form a significant component of the economy, history, and culture of southern California. Yet both the construction of dams and debris basins in coastal watersheds and the armoring of eroding coastal cliffs and bluffs have reduced sand supply. Ultimately, most of this beach sand is permanently lost to the submarine canyons that intercept littoral drift moving along this intensively used shoreline. Each decade the volume of lost sand is enough to build a beach 100 feet wide, 10 feet deep and 20 miles long, or a continuous beach extending from Newport Bay to San Clemente. Sea-level rise will negatively impact the beaches of southern California further, specifically those with back beach barriers such as seawalls, revetments, homes, businesses, highways, or railroads. Over 75% of the beaches in southern California are retained by structures, whether natural or artificial, and groin fields built decades ago have been important for local beach growth and stabilization efforts. While groins have been generally discouraged in recent decades in California, and there are important engineering and environmental considerations involved prior to any groin construction, the potential benefits are quite large for the intensively used beaches and growing population of southern California, particularly in light of predicted sea-level rise and public beach loss. All things considered, in many areas groins or groin fields may well meet the objectives of the California Coastal Act, which governs coastal land-use decisions. There are a number of shoreline areas in southern California where sand is in short supply, beaches are narrow, beach usage is high, and where sand retention structures could be used to widen or stabilize local beaches before sand is funneled offshore by submarine canyons intercepting littoral drift. Stabilizing and widening the beaches would add valuable recreational area, support beach ecology, provide a buffer for back beach infrastructure or development, and slow the impacts of a rising sea level.

scholarly journals Interdecadal Baroclinic Sea Level Changes in the North Pacific Based on Historical Ocean Hydrographic Observations

2015 ◽  
Vol 28 (11) ◽  
pp. 4585-4594 ◽  
Author(s):  
Tatsuo Suzuki ◽  
Masayoshi Ishii
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
North Pacific ◽  
Water Mass ◽  
Mass Density ◽  
Baroclinic Mode ◽  
Sea Level Changes ◽  
The North ◽  
Basin Scale ◽  
The North Pacific

Abstract Using historical ocean hydrographic observations, decadal to multidecadal sea level changes from 1951 to 2007 in the North Pacific were investigated focusing on vertical density structures. Hydrographically, the sea level changes could reflect the following: changes in the depth of the main pycnocline, density gradient changes across the pycnocline, and modification of the water mass density structure within the pycnocline. The first two processes are characterized as the first baroclinic mode. The changes in density stratification across the pycnocline are sufficiently small to maintain the vertical profile of the first baroclinic mode in this analysis period. Therefore, the first mode should represent mainly the dynamical response to the wind stress forcing. Meanwhile, changes in the composite of all modes of order greater than 1 (remaining baroclinic mode) can be attributed to water mass modifications above the pycnocline. The first baroclinic mode is associated with 40–60-yr fluctuations in the subtropical gyre and bidecadal fluctuations of the Kuroshio Extension (KE) in response to basin-scale wind stress changes. In addition to this, the remaining baroclinic mode exhibits strong variability around the recirculation region south of the KE and regions downstream of the KE, accompanied by 40–60-yr and bidecadal fluctuations, respectively. These fluctuations follow spinup/spindown of the subtropical gyre and meridional shifts of the KE shown in the first mode, respectively. A lag correlation analysis suggests that interdecadal sea level changes due to water mass density changes are a secondary consequence of changes in basin-scale wind stress forcing related to the ocean circulation changes associated with the first mode.

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