Sedimentological significance of strain and sonic velocity anisotropy in fine-grained turbiditic and hemipelagic deep-sea sediments — An example from the Mississippi Fan

Permeability values for a range of fine-grained deep-sea sediments are presented and evaluated in terms of index properties such as plasticity, grain size and carbonate content. It is found that whereas clay-rich sediments have similar permeabilities to those of equivalent land-based fine-grained soils, the presence of volcanic, carbonate and other non-clay fractions tends to increase permeability somewhat. Volcanic silty-clayey soils from Hawaii have comparable permeability values, although they can be slightly more permeable.

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Causes of compressional‐wave anisotropy in carbonate‐bearing, deep‐sea sediments

Geophysics ◽

10.1190/1.1441688 ◽

1984 ◽

Vol 49 (5) ◽

pp. 525-532 ◽

Cited By ~ 15

Author(s):

R. L. Carlson ◽

C. H. Schaftenaar ◽

R. P. Moore

Keyword(s):

Deep Sea ◽

Transversely Isotropic ◽

Compressional Wave ◽

Carbonate Content ◽

Velocity Anisotropy ◽

Acoustic Anisotropy ◽

Transversely Isotropic Media ◽

Deep Sea Sediments ◽

Isotropic Media ◽

Low Degrees

Forty indurated sediment samples from DSDP site 516 were studied with the principle objective of determining which of several proposed mechanisms is the cause of acoustic anisotropy in carbonate‐bearing deep‐sea sediments. Recovered from sub‐bottom depths between 388 and 1222 m, the samples have properties exhibiting the following ranges: wet‐bulk density, 1.90 to [Formula: see text]; fractional porosity, 0.46 to 0.14; carbonate content, 34 to 88 percent; compressional‐wave velocity (at 0.1 kbar), 1.87 to 4.87 km/sec; anisotropy, 1 to 13 percent. Velocities were measured in three mutually perpendicular directions through the same specimen in 29 of the 40 samples studied. Calcite fabric has been estimated by x‐ray pole figure goniometry. The major findings of this study are. (1) Carbonate‐bearing deep‐sea sediments may be regarded as transversely isotropic media with symmetry axes normal to bedding. (2) Calcite c‐axes are weakly concentrated in a direction perpendicular to bedding, but the preferred orientation of calcite does not contribute significantly to velocity anisotropy. (3) The properties of bedded and unbedded samples are distinctly different. Unbedded sediments exhibit low degrees of acoustic anisotropy (1 to 5 percent). By contrast, bedded samples show higher degrees of anisotropy (to 13 percent), and anisotropy increases markedly with depth of burial. Thus, bedding must be regarded as the principal cause of acoustic anisotropy in calcareous, deep‐sea sediments.

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Velocity anisotropy in semi-indurated calcareous deep sea sediments

Journal of Geophysical Research Atmospheres ◽

10.1029/jb084ib01p00205 ◽

1979 ◽

Vol 84 (B1) ◽

pp. 205-211 ◽

Cited By ~ 18

Author(s):

R. L. Carlson ◽

N. I. Christensen

Keyword(s):

Deep Sea ◽

Velocity Anisotropy ◽

Deep Sea Sediments

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Velocity Anisotropy and Physical Properties of Deep-sea Sediments from the Western South Atlantic

10.2973/dsdp.proc.39.124.1977 ◽

1977 ◽

Cited By ~ 6

Author(s):

R.L. Carlson ◽

N.I. Christensen

Keyword(s):

Physical Properties ◽

Deep Sea ◽

South Atlantic ◽

Velocity Anisotropy ◽

Deep Sea Sediments

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PALYNOLOGICAL RECORDS ON DEEP-SEA SEDIMENTS IN THE SOUTH CHINA SEA AND ITS PALEOENVIRONMENT

Marine Geology & Quaternary Geology ◽

10.3724/sp.j.1140.2009.01025 ◽

2009 ◽

Vol 29 (1) ◽

pp. 25-30 ◽

Cited By ~ 1

Author(s):

Yulan ZHANG

Keyword(s):

South China Sea ◽

South China ◽

Deep Sea ◽

The South China Sea ◽

The South ◽

China Sea ◽

Deep Sea Sediments ◽

Palynological Records

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Mechanism and Influencing Factors of REY Enrichment in Deep-Sea Sediments

Minerals ◽

10.3390/min11020196 ◽

2021 ◽

Vol 11 (2) ◽

pp. 196

Author(s):

Jiangbo Ren ◽

Yan Liu ◽

Fenlian Wang ◽

Gaowen He ◽

Xiguang Deng ◽

...

Keyword(s):

Deep Sea ◽

Research Progress ◽

Bottom Current ◽

Knowledge Map ◽

P2o5 Content ◽

Deep Sea Sediments ◽

Potential Resource ◽

And Migration ◽

Adsorption Desorption ◽

Sediment Interface

Deep-sea sediments with high contents of rare-earth elements and yttrium (REY) are expected to serve as a potential resource for REY, which have recently been proved to be mainly contributed by phosphate component. Studies have shown that the carriers of REY in deep-sea sediments include aluminosilicate, Fe-Mn oxyhydroxides, and phosphate components. The ∑REY of the phosphate component is 1–2 orders of magnitude higher than those of the other two carriers, expressed as ∑REY = 0.001 × [Al2O3] − 0.002 × [MnO] + 0.056 × [P2O5] − 32. The sediment P2O5 content of 1.5% explains 89.1% of the total variance of the sediment ∑REY content. According to global data, P has a stronger positive correlation with ∑REY compared with Mn, Fe, Al, etc.; 45.5% of samples have a P2O5 content of less than 0.25%, and ∑REY of not higher than 400 ppm. The ∑REY of the phosphate component reaches n × 104 ppm, much higher than that of marine phosphorites and lower than that of REY-phosphate minerals, which are called REY-rich phosphates in this study. The results of microscopic observation and separation by grain size indicate that the REY-rich phosphate component is mainly composed of bioapatite. When ∑REY > 2000 ppm, the average CaO/P2O5 ratio of the samples is 1.55, indicating that the phosphate composition is between carbonate fluoroapatite and hydroxyfluorapatite. According to a knowledge map of sediment elements, the phosphate component is mainly composed of P, Ca, Sr, REY, Sc, U, and Th, and its chemical composition is relatively stable. The phosphate component has a negative Ce anomaly and positive Y anomaly, and a REY pattern similar to that of marine phosphorites and seawater. After the early diagenesis process (biogeochemistry, adsorption, desorption, transformation, and migration), the REY enrichment in the phosphate component is completed near the seawater/sediment interface. In the process of REY enrichment, the precipitation and enrichment of P is critical. According to current research progress, the REY enrichment is the result of comprehensive factors, including low sedimentation rate, high ∑REY of the bottom seawater, a non-carbonate depositional environment, oxidation conditions, and certain bottom current conditions.

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