Modern accumulation rates and a sediment budget for the Eel shelf: a flood-dominated depositional environment

Sommerfield, Christopher K.; Nittrouer, Charles A.

doi:10.1016/s0025-3227(98)00115-7

Cited by 250 publications

(93 citation statements)

References 31 publications

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“…The excess 210 Pb activity profile in the sediments is commonly characterised by the maximum activity at the surface and by the exponential decay, and is used for the assessment of sediment accumulation rates under several assumptions, depending on the applied model (Robbins and Edgington, 1975;Nittrouer et al, 1979;Carpenter et al, 1982). However, the shape of the 210 Pb profile may also reveal information on changes in sediment accumulation rates, the presence of major erosional events and the presence of event layers (e.g., Nittrouer et al, 1979;Jaeger et al, 1998;Sommerfield and Nittrouer, 1999;Crockett et al, 2008;Szczuciński et al, 2009). An event layer can usually be observed in the portion of the 210 Pb activity profile that shows no change downcore (usually due to rapid deposition during the event).…”

Section: Methodsmentioning

confidence: 99%

Sedimentary deposits left by the 2004 Indian Ocean tsunami on the inner continental shelf offshore of Khao Lak, Andaman Sea (Thailand)

Sakuna

Szczuciński

Feldens³

et al. 2012

Earth Planet Sp

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Tsunami waves leave sedimentary signatures both onshore and offshore, although the latter are hardly known. The objective of the present study is to provide new evidence for the 2004 Indian Ocean tsunami deposits left on the inner continental shelf of the Andaman Sea (Thailand) and to identify diagnostic sedimentological and geochemical properties of these deposits. Based on extensive seafloor mapping, three sediment cores were selected for study and were analysed for their sedimentary structures, grain size composition, chemical elemental composition, physical properties and 210 Pb activity. Sediment cores retrieved from shallow water (9-15 m) within 7.5 km off the shore revealed distinct event layers, which were interpreted as being tsunami deposits. These 20-25 cm thick deposits were already covered with post-tsunami marine sediments. They were composed of several units, marine sand layers alternating with poorly sorted mud with terrigenous and anthropogenic components, representing different hydrodynamic conditions (probably during run-up and backwash phase). These sedimentological observations were supported by geochemical and physical data and were confirmed using 210 Pb dating. A sediment core taken from a depth of 57 m at a distance of 25 km offshore did not reveal clear event deposits. Comparisons with available data from offshore tsunami deposits showed that there is no single set of signatures that could be applied to identify this kind of deposits.

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Section: Methodsmentioning

confidence: 99%

Sedimentary deposits left by the 2004 Indian Ocean tsunami on the inner continental shelf offshore of Khao Lak, Andaman Sea (Thailand)

Sakuna

Szczuciński

Feldens³

et al. 2012

Earth Planet Sp

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“…In the Pacific Northwest of the United States, large storms both increase river discharge and produce strong southerly winds that disperse sediment northward on the shelf by way of the Davidson Current (Sternberg, 1986;Wheatcroft and others, 1997;Sommerfield and Nittrouer, 1999;Wolf and others, 1999). Sediment plumes are also observed to extend hundreds of kilometers seaward as evidenced by satellite imagery (Wheatcroft and others, 1997).…”

Section: Cascadia Physiography and Turbidite Depositionmentioning

confidence: 99%

Turbidite event history—Methods and implications for Holocene paleoseismicity of the Cascadia subduction zone

Goldfinger¹,

Nelson²,

Morey³

et al. 2012

Professional Paper

321

671

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“…Earlier coring and bathymetry work on the Eel margin con¢rmed that long-and short-term processes have created highly complex heterogeneous deposits (e.g., Orange, 1999;Sommer¢eld and Nittrouer, 1999). Fig.…”

Section: Regional Settingmentioning

confidence: 99%

In situ acoustic and laboratory ultrasonic sound speed and attenuation measured in heterogeneous soft seabed sediments: Eel River shelf, California

Gorgas

Wilkens

et al. 2002

Marine Geology

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We compared in situ and laboratory velocity and attenuation values measured in seafloor sediments from the shallow water delta of the Eel River, California. This region receives a substantial volume of fluvial sediment that is discharged annually onto the shelf. Additionally, a high input of fluvial sediments during storms generates flood deposits that are characterized by thin beds of variable grain-sizes between the 40-and 90-m isobaths. The main objectives of this study were (1) to investigate signatures of seafloor processes on geoacoustic and physical properties, and (2) to evaluate differences between geoacoustic parameters measured in situ at acoustic (7.5 kHz) and in the laboratory at ultrasonic (400 kHz) frequencies. The in situ acoustic measurements were conducted between 60 and 100 m of water depth. Wet-bulk density and porosity profiles were obtained to 1.15 m below seafloor (m bsf) using gravity cores of the mostly cohesive fine-grained sediments across-and along-shelf. Physical and geoacoustic properties from six selected sites obtained on the Eel margin revealed the following. (1) Sound speed and wet-bulk density strongly correlated in most cases. (2) Sediment compaction with depth generally led to increased sound speed and density, while porosity and in situ attenuation values decreased. (3) Sound speed was higher in coarser-than in finer-grained sediments, on a maximum average by 80 m s 31 . (4) In coarse-grained sediments sound speed was higher in the laboratory (1560 m s 31 ) than in situ (1520 m s 31 ). In contrast, average ultrasonic and in situ sound speed in finegrained sediments showed only little differences (both approximately 1480 m s 31 ). (5) Greater attenuation was commonly measured in the laboratory (0.4 and 0.8 dB m 31 kHz 31 ) than in situ (0.02 and 0.65 dB m 31 kHz 31 ), and remained almost constant below 0.4 m bsf. We attributed discrepancies between laboratory ultrasonic and in situ acoustic measurements to a frequency dependence of velocity and attenuation. In addition, laboratory attenuation was most likely enhanced due to scattering of sound waves at heterogeneities that were on the scale of

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Modern accumulation rates and a sediment budget for the Eel shelf: a flood-dominated depositional environment

Cited by 250 publications

References 31 publications

Sedimentary deposits left by the 2004 Indian Ocean tsunami on the inner continental shelf offshore of Khao Lak, Andaman Sea (Thailand)

Sedimentary deposits left by the 2004 Indian Ocean tsunami on the inner continental shelf offshore of Khao Lak, Andaman Sea (Thailand)

Turbidite event history—Methods and implications for Holocene paleoseismicity of the Cascadia subduction zone

In situ acoustic and laboratory ultrasonic sound speed and attenuation measured in heterogeneous soft seabed sediments: Eel River shelf, California

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