Consolidation, triaxial shear-strength, and index-property characteristics of organic-rich sediments from the Peru margin

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Hauptverfasser: Lee, Homa J, Kayen, Robert E, McArthur, William G
Format: Dataset Open Access
Sprache:en
Veröffentlicht: PANGAEA 1990
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_version_ 1867169502313054208
author Lee, Homa J
Kayen, Robert E
McArthur, William G
author_facet Lee, Homa J
Kayen, Robert E
McArthur, William G
collection Datos científicos de ciencias marinas y ambientales
contents Sites 679, 680, and 681 of the Ocean Drilling Program were drilled along an east-west transect across an organic-rich, diatomaceous, coastal upwelling facies that occurs as a shelf/slope lens along the Peru continental margin. Seven 60-cm-long, unsplit core sections from these sites were tested for consolidation, triaxial shear strength, and geotechnical index properties. The testing showed that the sediment has unusually high water content, Atterberg limits, degree of overconsolidation, compressibility, and shear strength. The sediment has unusually low density and grain specific gravity. Atterberg limits, grain specific gravity, compressibility, and apparent excess maximum past stress increase linearly with organic-carbon content, which also correlates positively with diatom content. Overconsolidation measured in these tests is probably not a result of sediment erosion or slumping, but rather the result of diagenesis or interparticle bonding by organic matter. High shear strengths were measured throughout, but particularly high relative shear strengths (as indicated by friction angles and degrees of dilatancy during shear) occur near 20 mbsf. This "crustlike" behavior is probably produced by early diagenesis (perhaps including dolotomization) within the upper 20 m, and is complemented by interlocking of diatoms.
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publishDate 1990
publisher PANGAEA
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spellingShingle Consolidation, triaxial shear-strength, and index-property characteristics of organic-rich sediments from the Peru margin
Lee, Homa J
Kayen, Robert E
McArthur, William G
112-679C; 112-680C; 112-681C; DRILL; Drilling/drill rig; Joides Resolution; Leg112; Ocean Drilling Program; ODP; South Pacific Ocean
Sites 679, 680, and 681 of the Ocean Drilling Program were drilled along an east-west transect across an organic-rich, diatomaceous, coastal upwelling facies that occurs as a shelf/slope lens along the Peru continental margin. Seven 60-cm-long, unsplit core sections from these sites were tested for consolidation, triaxial shear strength, and geotechnical index properties. The testing showed that the sediment has unusually high water content, Atterberg limits, degree of overconsolidation, compressibility, and shear strength. The sediment has unusually low density and grain specific gravity. Atterberg limits, grain specific gravity, compressibility, and apparent excess maximum past stress increase linearly with organic-carbon content, which also correlates positively with diatom content. Overconsolidation measured in these tests is probably not a result of sediment erosion or slumping, but rather the result of diagenesis or interparticle bonding by organic matter. High shear strengths were measured throughout, but particularly high relative shear strengths (as indicated by friction angles and degrees of dilatancy during shear) occur near 20 mbsf. This "crustlike" behavior is probably produced by early diagenesis (perhaps including dolotomization) within the upper 20 m, and is complemented by interlocking of diatoms.
title Consolidation, triaxial shear-strength, and index-property characteristics of organic-rich sediments from the Peru margin
topic 112-679C; 112-680C; 112-681C; DRILL; Drilling/drill rig; Joides Resolution; Leg112; Ocean Drilling Program; ODP; South Pacific Ocean
url https://doi.org/10.1594/PANGAEA.753807