Biological alteration of physically structured flood deposits on the Eel margin, northern California

Cutter, G.R.; Díaz, Robert J.

doi:10.1016/s0278-4343(99)00059-x

Cited by 22 publications

(12 citation statements)

References 34 publications

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“…Box-core sediment samples showed a dominance of ¢ne-grained and cohesive sediments with a mean grain size around 7P (Richardson et al, 2002), which corresponded to values obtained by others (e.g., Borgeld et al, 1999;Drake, 1999;Cutter and Diaz, 2000).…”

Section: Density Porosity and Mean Grain Sizesupporting

confidence: 88%

“…The bulk of discharged £uvial sediments is transported further o¡shore and deposited below the zone of high turbulence (Wiberg et al, 1996;Cacchione et al, 1999). Subsequently, the sea£oor is signi¢-cantly bioturbated over time causing a downcore coarsening of some deposits until the next £ood deposit recharges this part of the shelf with more sediment (Wiberg et al, 1996;Wheatcroft et al, 1996Wheatcroft et al, , 1997Drake, 1999;Cutter and Diaz, 2000). The lower strata of a £ood deposit from 1995 most likely represent remnants of older £ood deposits which have been partly eroded during storm periods, and reworked by biological processes (Go¡ et al, 1996Borgeld et al, 1999).…”

Section: Regional Settingmentioning

confidence: 99%

“…3C and 5C) re£ects rapid sediment deposition without signi¢cant compaction time (Wheatcroft et al, 1996(Wheatcroft et al, , 1997. It has been suggested that parts of the shelf below 60 m water depth have been built as a sequence of compacted £ood deposits, which have been altered over time by bioturbation and erosion due to bottom currents (Go¡ et al, 1996Cutter and Diaz, 2000). The sur¢cial morphology of this sequence of remnant and more recent deposits provides evidence for the prevalent direction of bottom currents from south to north during storm events, while current directions are reversed in storm-free periods (Cacchione et al, 1999).…”

Section: Geoacoustic Properties Governed By Environmental Factorsmentioning

confidence: 99%

“…These properties of marine sediments at the benthic boundary layer are generally controlled by the interaction of biological, biogeochemical, geological and hydrodynamic processes (Richardson et al, 1983;Briggs et al, 1985;Richardson and Briggs, 1996). Results from previous studies on the Eel margin and in similar environments concluded that biological activity could directly alter the acoustic and physical structure of the subsurface in a random fashion down to 0.3 m bsf (e.g., Drake, 1999;Cutter and Diaz, 2000). For example, bioturbation may disturb laminated zones that were formerly created by erosion and depositional events (Richardson and Young, 1980;Richardson, 1986;Ogston and Sternberg, 1999).…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Density Porosity and Mean Grain Sizesupporting

confidence: 88%

Section: Regional Settingmentioning

confidence: 99%

Section: Geoacoustic Properties Governed By Environmental Factorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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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“…The geometry of burrows created by infauna depends on the species present, population density, as well as the physiological responses of infauna to environmental factors, all of which are in turn dictated by the climatological, geological and oceanographical characteristics of each particular site [Cutter and Diaz, 2000]. These properties are always site-, season-and species-specific, making generalization attempts difficult.…”

Section: Laterally Heterogeneous Solute Transport Geometry Due To Burmentioning

confidence: 99%

Biogeochemical consequences of infaunal activities

Furukawa¹

2005

Coastal and Estuarine Studies

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The public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, Activities of sedimentary infauna have significant consequences on overall sedimentary diagenesis. Infauna directly participate in sedimentary processes by organic matter metabolization coupled to aerobic respiration and metabolite excretion. In addition, they indirectly influence the diagenetic pathways by changing the transport regimes of dissolved and particulate species as well as by modifying microbial habitats. The couplings between infaunal activities and their biogeochemical consequences have been studied in recent years, but many of the results and conclusions remain site-and species-specific due to the diverse and highly interrelated ways in which sedimentary infauna interact with the transport. reaction, and microbial regimes. A generalized understanding of infauna-influenced sedimentary systems will require (It a systematic classification of the infauna-sediment interaction mechanisms Activities of sedimentary infauna have significant consequences on overall sedimentary diagenesis. Infauna directly participate in sedimentary processes by organic matter metabolization coupled to aerobic respiration and metabolite excretion. In addition, they indirectly influence the diagenetic pathways by changing the transport regimes of dissolved and particulate species as well as by modifying microbial habitats. The couplings between infaunal activities and their biogeochemical consequences have been studied in recent years, but many of the results and conclusions remain site-and species-specific due to the diverse and highly interrelated ways in which sedimentary infauna interact with the transport, reaction, and microbial regimes. A generalized understanding of infauna-influenced sedimentary systems will require (1) a systematic classification of the infauna-sediment interaction mechanisms and (2) a comprehensive model framework that incorporates all known effects of infauna-sediment interactions associated with transport, reaction, and microbial regimes.

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Writing a Rosetta Stone: Insights into Continental‐Margin Sedimentary Processes and Strata

Nittrouer

Austin

Field

et al. 2007

Continental Margin Sedimentation

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Continental margins are valuable for many reasons, including the rich record of Earth history that they contain. A comprehensive understanding about the fate of fluvial sediment requires knowledge that transcends time-scales ranging from particle transport to deep burial. Insights are presented for margins in general, with a focus on a tectonically active margin (northern California) and a passive margin (New Jersey). Formation of continental-margin strata begins with sediment delivery to the seabed. Physical and biological reworking alters this sediment before it is preserved by burial, and has an impact upon its dispersal to more distal locations. The seabed develops strength as it consolidates, but failure can occur and lead to sediment redistribution through high-concentration gravity flows. Processes ranging from sediment delivery to gravity flows create morphological features that give shape to continental-margin surfaces. With burial, these surfaces may become seismic reflectors, which are observed in the subsurface as stratigraphy and are used to interpret the history of formative processes. Observations document sedimentary processes and strata on a particular margin, but numerical models and laboratory experimentation are necessary to provide a quantitative basis for extrapolation of these processes and strata in time and space.

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Biological alteration of physically structured flood deposits on the Eel margin, northern California

Cited by 22 publications

References 34 publications

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

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

Biogeochemical consequences of infaunal activities

Writing a Rosetta Stone: Insights into Continental‐Margin Sedimentary Processes and Strata

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