Engineering and Other Physical Property Data, Leg 43

Demars, Kenneth R.; Nacci, V.A.; Kelly, William E.

doi:10.2973/dsdp.proc.43.135.1979

Cited by 3 publications

(6 citation statements)

References 7 publications

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“…The disturbance to samples caused by rotary drilling has been the subject of several studies (Demars and Nacci, 1978;Demars et al, 1979;Lee, 1973;Bennett and Keller, 1973). All these authors conclude that the churning of the rotary drill bit and the excess back-pressure of drilling muds tend to homogenize and severely disturb the sediment.…”

Section: Disturbancementioning

confidence: 99%

“…Vane shear strength is affected both by remolding and by changes in water content. Demars et al (1979) report that shear strengths measured on DSDP samples may be more than 75% less than in situ values. Lee (1973) attempted to correct for drilling disturbance by measuring residual stresses and concluded that in situ strengths are two to three times greater than those of DSDP samples.…”

Section: Disturbancementioning

confidence: 99%

“…Though the primary cause for this improvement in sample quality is the absence of drill string rotation and drilling fluid pumping, several other factors add to the relatively undisturbed appearance of the HPC cores. Demars et al (1979) identified volume increase due to swelling as a secondary cause of disturbance in DSDP samples (drained unloading). They attribute this disturbance to poor sample-liner fit resulting in water or drill mud between the sample and the liner.…”

Section: Disturbancementioning

confidence: 99%

“…In particular, Deep Sea Drilling Project cores have provided an opportunity to study variations of physical properties to great depths below the seafloor and have resulted in important contributions to our understanding of deep sea sedimentation (Keller and Bennett, 1973;Bennett and Keller, 1973;Lee, 1973;Rocker, 1974;Schlanger and Douglas, 1974;Trabant et al, 1975;Tucholke et al, 1976;Trabant, 1978;Demars et al, 1979). These studies, however, have all been hampered by the sometimes severe disturbance caused by rotary drilling and the consequent difficulty in recovering continuous sections.…”

Section: Introductionmentioning

confidence: 99%

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Physical Properties of Sediment Recovered on Deep Sea Drilling Project Leg 68 with the Hydraulic Piston Corer

Mayer¹

1982

Initial Reports of the Deep Sea Drilling Project

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Section: Disturbancementioning

confidence: 99%

Section: Disturbancementioning

confidence: 99%

Section: Disturbancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Physical Properties of Sediment Recovered on Deep Sea Drilling Project Leg 68 with the Hydraulic Piston Corer

Mayer¹

1982

Initial Reports of the Deep Sea Drilling Project

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“…In previous DSDP reports, the different methods are well described, notably by Boyce (1976aBoyce ( , 1977. So too are the general problems associated with physical property measurements in conventionally cored material (Bennett and Keller, 1973;Demars et al, 1979;von Huene et al, 1973).…”

Section: Introductionmentioning

confidence: 99%

The Influence of Sediment Composition on Physical Properties Interrelationships

Bayer¹

1983

Initial Reports of the Deep Sea Drilling Project

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Physical properties measured in Mesozoic to Recent sediments at DSDP Sites 511-514 are summarized, compared, and related to sedimentological composition. Lithification in clays and nannofossil oozes starts at porosities of less than 60% and affects sonic velocity very strongly, whereas compaction causes little increase in sonic velocity. Shear strength increases rapidly with decreasing porosity within all observed lithologies (clays, nannofossil, and diatomaceous oozes). In diatomaceous oozes and muds the stress-strain relationship of the vane shear test depends on the anisotropic properties of the sediment. Within Tertiary and younger sediments, physical properties other than shear strength depend much more on sedimentological composition than on compaction, which is measured from the porosity data. The physical properties data are viewed as the output of the developing sediment "system" and are related through simple interaction models.

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A study of the seismic structure of upper oceanic crust using wide-angle reflections

Rohr¹

1983

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The lateral homogeneity of oceanic crust on the scale of a seismic experiment is a condition that most methods of seismic interpretation depend on. Whether this condition is in fact true is largely unknown and only recently have efforts been made to test this hypothesis. This thesis is part of that effort and is focussed on determining with as much resolution as possible the seismic structure of upper oceanic crust, i.e. Layer 1 and the uppermost part of Layer 2. This portion of the crust is of interest, because of the effect of the sediment-basement interface on the transmission and conversion of seismic energy, also because of the possibility of detecting lateral heterogeneities in upper Layer 2 caused by faulting, hydrothermal circulation etc. The data employed are a set of wide-angle reflections from oceanic crust 130 m.y. old in the western North Atlantic Ocean southwest of Bermuda. First, the sedimentary structure is determined by stacking the data along hyperbolae and interpreting the stacking velocities and two-way normal incidence travel-times for interval velocities. This method has not been applied to deep sea marine data before; it gives a more detailed velocity structure of the sediments than does a traditional study of the basement reflections' travel-times. Second, the same data are mapped into tau-p space in order to measure the velocity gradient in oceanic basement; unfortunately the scatter in the tau-p picks caused by the topography of the basement reflector combine with the properties of the tau-sum inversion to make such a measurement impossible. Third, the amplitudes of the basement reflections observed on three seismic lines are modelled by synthetic seismograms; each can be matched by velocity-depth models which contain a transition zone between the sediments and the basement. The different thicknesses of this transition zone near the three receivers is an indication that the top few hundred meters of Layer 2 are laterally heterogeneous on a scale of 3 to 8 km.id ACKNOWLEDGEMENTS

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Engineering and Other Physical Property Data, Leg 43

Cited by 3 publications

References 7 publications

Physical Properties of Sediment Recovered on Deep Sea Drilling Project Leg 68 with the Hydraulic Piston Corer

Physical Properties of Sediment Recovered on Deep Sea Drilling Project Leg 68 with the Hydraulic Piston Corer

The Influence of Sediment Composition on Physical Properties Interrelationships

A study of the seismic structure of upper oceanic crust using wide-angle reflections

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