Consolidation Test Results and Porosity Rebound of Ontong Java Plateau Sediments

Marsters, Janice C.; Manghnani, Murli H.

doi:10.2973/odp.proc.sr.130.044.1993

Cited by 6 publications

(12 citation statements)

References 18 publications

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“…The question of signi®cant cementation in the chalk interval was addressed by Audet (1995). On the basis of soil mechanics and porosity data Audet developed a mathematical model for the compaction of the ooze of the Ontong Java Plateau, and estimated mechanical parameters consistent with the data obtained by consolidation tests on the ooze material (Marsters & Manghnani, 1993;Lind, 1993b). Audet's (1995) model overestimates the porosity in the chalk interval relative to the consolidation data from the chalk interval (Lind, 1993b).…”

Section: Interpretation Of Compaction Studies On Ooze and Chalkmentioning

confidence: 99%

Chemical and mechanical processes during burial diagenesis of chalk: an interpretation based on specific surface data of deep‐sea sediments

Borre¹,

Fabricius²

1998

Sedimentology

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Burial diagenesis of chalk is a combination of mechanical compaction and chemical recrystallization as well as cementation. We have predicted the characteristic trends in specific surface resulting from these processes. The specific surface is normally measured by nitrogen adsorption but is here measured by image analysis of scanning electron micrographs. This method concentrates on the micritic matrix alone. Deep‐sea sediments are ideally suited to the study of burial diagenesis because they accumulate in a relatively conservative tectonic setting. We used material from the Ontong Java Plateau in the Pacific, where a > 1 km thick package of chalk facies sediments accumulated from the Cretaceous to the present. In the upper 200–300 m the sediment is unconsolidated carbonate ooze, throughout this depth interval compaction is the principal porosity reducing agent, but recrystallization has an equal or larger influence on the textural development. In the chalk interval below, compaction is not the only porosity reducing agent but it has a larger influence on texture than concurrent recrystallization. Below 850 m grain‐bridging cementation becomes important resulting in a lithified limestone below 1100 m. This interpretation is based on specific surface data alone, and modifies current diagenetic models.

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Section: Interpretation Of Compaction Studies On Ooze and Chalkmentioning

confidence: 99%

Chemical and mechanical processes during burial diagenesis of chalk: an interpretation based on specific surface data of deep‐sea sediments

Borre¹,

Fabricius²

1998

Sedimentology

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“…13) for the ooze data (solid curve) and the chalk data (dashed curve) are shown, assuming that the boundary condition is a,=10 kPa in both cases. The values of C, and i5,,, determined Marsters & Manghnani (1993) used a triaxial apparatus and measured the compression curves for ooze samples recovered from the Ontong Java Plateau. Lind (1993) used an oedometer and studied both oozes and chalks from Sites 803 and 807.…”

Section: Compaction Trends In Oozes and Chalksmentioning

confidence: 99%

“…The compression properties of ooze samples from Leg 130 were measured by Marsters & Manghnani (1993) and Lind (1993). Lind also measured the strength of chalk samples.…”

Section: Introductionmentioning

confidence: 99%

Modelling of porosity evolution and mechanical compaction of calcareous sediments

Audet

1995

Sedimentology

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A continuum mechanics model for the gravitational compaction of sediments is derived by assuming that the sediments are normally pressured and in a one‐dimensional state of stress. Sediment strength is characterized in terms of effective stress laws adopted from soil mechanics. The model is a relatively simple mathematical formula that gives the porosity as a function of burial depth. The shape of the porosity profile is controlled by two mechanical parameters, the compression index and the void ratio at an effective stress of 100 kPa. The model was verified by analysing the porosity—depth data of oozes and chalk from the Ontong Java Plateau, gathered during Leg 130 of the Ocean Drilling Program. The mechanical parameters of the sediments were estimated using a least‐squares method to fit the theoretical profile to the porosity data. The theoretical profile described accurately the ooze porosity data over depth ranges of 100 m or more. However, over smaller length‐scales of 10–50 m there were systematic deviations between the theoretical porosity values and the ooze porosity data. The porosity deviations correlated with variations in the mean grain size of the sediments, due in part to changes in the foraminifera abundance. In the case of the oozes, the estimated mechanical parameters were consistent with published values obtained from one‐dimensional compression tests. In contrast, the estimated mechanical properties for the chalks differed from published values. The chalk porosities were lower than could be explained by mechanical compaction. This explanation is supported by the compressional (P‐wave) velocity data. In the chalk sections, the P‐wave velocity increases more rapidly with burial depth than it does in the ooze sections, suggesting that sediment elastic properties are increasing due to interparticle binding.

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“…shows that laboratory densities are systematically lower, by about 0.04 gcm -3, than corresponding log values. This small difference in the Hole 807A ooze-chalk data is consistent with an earlier laboratory-log comparison of pelagic carbonates [Nobes etal., 1991] and with laboratory consolidation tests from pelagic carbonates [Hurley and Hempel, 1990;Lind, 1993;Marsters and Manghnani, 1993]. Discrepancies between log and laboratory densities can be accounted for by hydraulic rebound of sediment pore waters, which decrease in density when transferred from pressures and temperatures at the seafloor to laboratory conditions.…”

Section: A Cross Plot Of Laboratory and Log Density Data In Figure 2amentioning

confidence: 99%

“…This estimated mechanical porosity rebound has been used with velocity-porosity cross plots as the principal method for correcting laboratory velocity measurements to in situ values for a wide range of marine sediment lithologies [e.g., Boyce, 1976, 1980; Shipley, 1983; Mayer et al, 1985a; Hempel et al, 1989].In the case of pelagic marine carbonate sediments, there is a growing body of evidence that mechanical rebound of porosity in core samples is not as great as the rebound predicted from laboratory consolidation tests used by Hamilton [1976]. Recent studies using both laboratory consolidation tests [Hurley and Hempel, 1990;Lind, 1993;Marsters and Manghnani, 1993] and comparisons of laboratory and in situ geophysical borehole well logs [Nobes et al, 1991; Urmos et al, 1993] have revealed that mechanical rebound of core samples is small. In no case does rebound in pelagic carbonates approach the 5% maximum porosity increase predicted from the empirical carbonate rebound function of Hamilton [1976].…”

mentioning

confidence: 99%

In situ velocities in pelagic carbonates: New insights from Ocean Drilling Program Leg 130, Ontong Java Plateau

Urmos¹,

Wilkens²

1993

J. Geophys. Res.

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Ocean Drilling Program Leg 130 returned an extensive suite of in situ borehole logging and closely spaced shipboard physical properties measurements from four sites drilled in carbonate‐rich pelagic oozes and chalks on the Ontong Java Plateau. Using these data, we evaluated factors responsible for observed differences between laboratory data and in situ values. Laboratory and log differences for bulk density/porosity are small and nearly constant and can be accounted for by hydraulic rebound of pore fluid following sediment recovery. Evidence for mechanical rebound of sediments was not observed. Velocity‐porosity relationships cannot be used to indirectly correct laboratory velocities to in situ because fundamental assumptions required for rebound corrections are not satisfied. Velocity‐porosity systematics are also complicated by foraminiferal intraparticle porosity variations. We derived empirical laboratory velocity corrections using log and laboratory velocity differences expressed as functions of depth and effective pressure. We tested the velocity corrections using data for carbonates recovered from Ocean Drilling Program Sites 704, 722, and 762; comparisons with logs show that corrected velocities accurately estimate in situ values for oozes and chalks (CaCO3 >60%). For applications to unlogged Deep Sea Drilling Project Leg 85 sites, igneous basement travel times calculated using corrected velocities agree with acoustic basement travel times from seismic records, implying that corrected velocities are realistic in situ estimates. At Site 574, we used our corrected velocities to reevaluate previous lithostratigraphic and seismostratigraphic correlations based on mechanical rebound‐corrected velocities. The new velocities correlate reflectors to progressively greater core depths. Although changes are minor above 200 m below seafloor, the lowest assigned reflector is shifted 36 m deeper to more closely coincide with a diagenetic boundary and acoustic basement correlates with igneous basement instead of with postulated high‐impedance reflectors within the sediments.

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Consolidation Test Results and Porosity Rebound of Ontong Java Plateau Sediments

Cited by 6 publications

References 18 publications

Chemical and mechanical processes during burial diagenesis of chalk: an interpretation based on specific surface data of deep‐sea sediments

Chemical and mechanical processes during burial diagenesis of chalk: an interpretation based on specific surface data of deep‐sea sediments

Modelling of porosity evolution and mechanical compaction of calcareous sediments

In situ velocities in pelagic carbonates: New insights from Ocean Drilling Program Leg 130, Ontong Java Plateau

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