32. Diffusimetry (Diffusion Constant Estimation)

32. DIFFUSIMETRY (DIFFUSION CONSTANT ESTIMATION) ON SEDIMENT CORESBY RESISTIVITY PROBE1

Frank T. Manheim, United States Geological Survey, Woods Hole, Massachusettsand

Lee S. Waterman, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts

ABSTRACT

Measurement of formation factor (ratio of rock resistivity tointerstitial water resistivity) from sediment cores provides anindirect measurement of the tortuosity of the fluid channels inthe sediments. From these measurements one can estimate thediffusion coefficient of the sediment with depth. The F (forma-tion factor) values for Indian Ocean sediments varied from 1.6 fora clayey diatom ooze having 87% porosity (70% water content)to 13.6 for a cemented limestone having 25% porosity (11%water content). These formation factors would yield diffusioncoefficients for chloride ions in the corresponding sediments of6.4 × I 0 - 6 to 1.5 × 10-6 cm2/sec. In general, surficialsediments showed diffusion coefficients about one-half to one-third of those for free solution, values decreasing with depth andporosity.

INTRODUCTION

The permeability of porous sediments to movement ofions and molecules is an important property since it governsthe rate at which migration, loss or gain of dissolvedconstituents, may proceed via the interconnected fluidchannels. The diffusive properties of relatively poroussediments are known to some degree through laboratoryexperiments (Manheim, 1970; Smirnov, 1971) and can beinferred indirectly by electrical measurements. However,whereas substantial data are available from electrical loggingmeasurements in drill holes, particularly in oilfield work(Pirson, 1963) these data refer almost exclusively toreservoir, or permeable rocks such as sandstones andpermeable limestones. Only a few studies have attempted toobtain data on relatively impermeable materials such asshales, shaly sands, or tight limestones. In particular, thereappear to be only two systematic studies applicable toelucidating the diffusive permeability of sediments down-ward from the sea floor (Zatenatskaya, 1965; Keller, 1969).Such data are needed to understand the exchange ofmaterials within the sediments and between the depositsand overlying ocean waters.

In principle, the manner in which electrolyte-saturatedsediments transmit electrical current is analogous to theirability to allow molecular diffusion. The diffusivity ofdissolved species within sediments is a function of thespecies themselves; the temperature, viscosity, and otherphysical properties of the solution; and the porosity and

1 Contribution No. 2784 of the Woods Hole OceanographicInstitution. Publication approved by the Director, United StatesGeological Survey.

tortuosity (geometry) of the free channels in the sediment.Since the electrical resistivity of many mineral particles isvery large compared with electrolyte solutions, one canoften ignore the proportion of current carried by the solids.Under such conditions the diffusion coefficient of a givenmolecule or ionic species within the sediment is given by

d = — - d0Rw/Rs (1)

where d0 is the diffusion coefficient for the given species infree solution at a given temperature and ionic strengthsolution, Rw is the electrical resistivity of the interstitialwater of the sediment, and Rs is the bulk electricalresistivity of the sediment. F, or Rs/Rw, is the formationfactor. Alternatively,

d = -77 = (2)

where Cs and Cw are corresponding conductivities andF=CW/CS.

Where the sediments in question contain high propor-tions of clay with respect to fluid, the clays may conduct asignificant part of the current, and the above relationshipwill no longer be applicable. Under these conditions

l/Rs = URc+lfRw (3)

where Rc is the resistivity of the clay component, or

~ Or (4)

using conductivities.

663

F. T. MANHEIM, L. S. WATERMAN

No simple correction can be made for clay resistivity orconductivity, however, because the total conductivity is acomplex function of the geometry of the pore distributionand interaction of the electrolytes with the clay. For manysands and sandstones, the simple Archie relationship holds:

Φ2 (5)

where 0 = porosity.

For clays, the exponent may vary from 2.5 to 5.4 (Atlanet al., 1968). However, these investigators also showed thatthe contribution by clay to rock resistivity can be quitewell characterized by clay type and particularly baseexchange capacity of the sediment. For example, thelimiting conductivity for illites having a base exchangecapacity of about 25 meq/100 g is on the order of 0.2mho/m or 5 ohm/m resistivity for sediments permeatedwith saline solutions of seawater ionic strength or greater.This indicates that deriving diffusion coefficients for Leg 22sediments from the electrical measurements will normallyinvolve an error smaller than the scatter of values attribut-able to local variability in lithology and uncertainty due totemperature gradients. The actual error may sometimesexceed about 10%. In such instances, the apparent diffusioncoefficients will be systematically higher than the truevalues.

Diffusion coefficients are sensitive to temperature.Because information on temperature gradients is notavailable, the diffusion coefficient cannot be corrected forin situ temperature. At the greatest depths, temperaturemay be significantly higher than 25° (perhaps reaching 35°)whereas at shallow depths, temperatures similar to those atthe sea floor (1-2°) are anticipated. Such differences involvea change in diffusion coefficient on the order of a factor of2*4.

Preliminary experiments, using a two-electrode probeand a Beckman resistivity bridge to measure sediment andfluid resistivity, showed that polarization effects withstainless steel, copper, brass, and platinum electrodesrendered them useless for salinities above 0.1 iV NaCl.Platinized platinum, commonly used for laboratory meas-urements, was regarded as unfeasible because of thedelicacy of electrode surface and probable damage byabrasive sediments. However, 1/8-in. diameter spectro-graphic graphite electrodes, when pointed in a pencilsharpener, appear to yield acceptable results even withstrong brines. This system was placed aboard GlomarChallenger for the special geochemical study on Leg 15.However, W. S. Broecker, who tested the system, reportedthat the graphite electrodes tended to break, and unexplain-ably large shifts in calibration resistivities occurred. Sub-sequently, a 4-electrode device was employed, which hasproved much more successful and sturdy for the measure-ments made on Legs 22 and 23B.

METHODS

The construction of the probe and the 4-electrode testcircuit are shown in Figures 1 and 2. The outer twoelectrodes supply the AC current .(high frequency), whereas

the inner electrodes are used to measure the potential. Withthis system, polarization effects are minimized, since it isthe relative potential drop between inner electrodes thatdetermines the measured resistivity. Electrodes are insertedinto a medium whose depth may be infinite with respect toinvestigative radius of the inner electrodes, or may be finite.In simplified form, the resistivity of an assumed semi-infinite medium is given by:

R = 2V/Ir2r\

(6)

(Jakosky, 1950) where V is the potential difference, r^and r\ are the respective distances of the inner elec-trodes from the power electrodes, and / is the cur-rent flowing between the power electrodes. The sedi-ment medium is assumed to be isotropic. Thus, the specificresistance of any medium is directly proportional to thepotential measured, if the current and spacing are heldconstant. The resistivities are measured on a Model EMT-Cportable mud tester (Schlumberger Well Surveying Corp-,Houston, Texas).

In principle, the electrodes' cell constant is first deter-mined for the exact geometry of the container chosen tohold the sediment samples, using surface ocean water asreference fluid. Then the probe is inserted into thesediment and the resistivity measured. The' resistivity ofboth the reference fluid and the interstitial water squeezed

1 2

1. Stainless steel pin, 3/32" (2.4 mm) diameter, insertedin push-in screw receptacle.

2. Polyvinyl chloride cover plate, 1/4" thickness, dri l ledto accommodate electrode pins.

3. Stainless steel housing.4. PVC insert, holding (5).5. Electrode contact receptacles, screwed into insert.6. 0-ring to prevent moisture from entering interior

of housing.7. Screws to grip PVC insert.8. Rubber stopper bored and s l i t to accommodate electr ical

cable.9. 4-conductor cable, soldered to electrode contacts.

Figure 1. Probe construction.

Px

Figure 2. Electrode circuit.

664

DIFFUSIMETRY ON SEDIMENT CORES BY RESISTIVITY PROBE

from the same sediment (Waterman, 1970) are determinedon a small, calibrated resistivity cell. Temperature correc-tions are applied to bring both sediment and interstitialwater measurements to the same basis, and the formationfactor is determined.

In practice the following steps are taken:(1) Determine apparent resistivity of the sediment by

inserting the probe into the end of a 10-cm mini-core cutfrom a standard 150-cm section of core. In cases where it isnot possible to obtain a mini-core, e.g., core-catcher sample,the probe is inserted into a relatively flat surface on thesediment lump. The temperature is determined using aWeston stainless steel dial thermometer.

(2) Determine the resistivity of a volume of referencefluid which closely approximates the geometry and volumeof the sediment. A container made from a length of plasticcore liner is filled to the brim with the reference fluid andthe electrodes submerged to the same depth as wheninserted into the sediment. The probe is supported by aplate having a larger diameter than the top of the container.The temperature of the reference fluid is determined. Avariety of small plastic cups is used to approximate the sizeand shape of sediment samples taken from the core catcher.A sufficiently large volume of surface ocean water iscollected at the beginning of the leg so that the samereference fluid can be used throughout the cruise.

(3) Determine resistivity of the interstitial fluid usingthe small calibrated cell. The temperature of the pore wateris determined with a glass laboratory thermometer attachedto the cell. The salinity is determined from refractometer(index of refraction) measurements. About \λh ml of porefluid is necessary for the resistivity measurement.

(4) Determine resistivity of the reference fluid using thecalibrated cell as described above.

(5) The probe assembly is partially disassembled forcleaning. The polyvinyl chloride plate is removed and theelectrodes pulled out of their sockets. All pieces are washedwith fresh water using tissues to rub off clinging sedimentand salt accumulation, then rapidly dried with acetonedispensed from a wash bottle. The unit is reassembled.

(6) Calculations: The cell constant, k, is the trueresistivity at t°C for reference fluid (small cell) divided bythe apparent resistivity in sample cup or configuration.Corrected resistivity of sediments is obtained by multiply-ing the apparent value (directly measured) by the cellconstant. Temperature corrections are determined graph-ically (Figure 3). Find the apparent salinity correspondingto determined resistivity at the appropriate temperature.Move horizontally to the desired (interpolated) tempera-ture. The new resistivity value will be found on the bottomscale directly below. Formation factor, F = Rs/Rfw, whereRs is the corrected sediment resistivity and Rjw is theresistivity of the interstitial water. Diffusion constants areobtained from Equation 1. Porosity is calculated fromwater content using the graph shown in Figure 4.

If the core is partly consolidated or lithified, preliminaryholes are bored into the sediment using a 1/8-in. twist drilland a plastic template which serves both as a position anddepth guide. Drills wear out and must be replaced oftenwhen drilling in hard sediment such as sandy carbonates.The apparent resistivity is determined as described above;

an additional measurement is made after checking theprobe to firmly seat the electrodes. When there is doubtabout adequate contact between the pins and the sediment,a few drops of ocean water may be placed in each of theholes. Precautions are taken when obtaining and storingmini-cores to minimize drying from exposure to theatmosphere before the resistivity measurements are carriedout. The condition of the mini-core (e.g., state of con-solidation, drilling slurry, obvious disruption of material bydrilling, cracks resulting from the drilling of holes to insertthe probes, etc.) is recorded when appropriate.

RESULTS AND DISCUSSION

The data and calculations summarized in Tables 1through 7 show that the lowest formation factors (1.6)occur in very porous diatom-radiolarian oozes near thesurface of Site 215. Ordinary nannoplankton oozes and siltsshowed F factors of about 3 in the uppermost sections. Themost marked increases in the F factor (decreases indiffusion coefficient) with depth occurred in nannofossilooze-chalks at Site 217, where maximum F values of 13.6were obtained. These values correspond to lithified lime-stones having a porosity of only 25% (water content of11%). However, interspersed between the poorly permeablesediments are deposits showing lower F factors.

As indicated earlier, one can draw some conclusionsabout the nature of F factors and hence diffusive capacityof sediment from the proportion and kind of reactive claysor other minerals having appreciable ion exchange capacity.Conversely, from the porosity, F factor data, and the dataof Atlan et al. (1968), the exchange capacity of thesediments can also be estimated in a rough way. Figure 5 isconstructed from data relating exchange capacity of a seriesof clays including kaolinites, illites, and montmorillonites,with porosity and conductivity. Thus, for Site 215, thesurficial diatom-radiolarian oozes are indicated to have anexchange capacity of somewhat more than 3 meq/100 g.On the other hand, between 68 and 76 meters an exchangecapacity of between 30 and 40 meq/100 g is indicated,values which would be in agreement with the clayey-zeoliticnature of the sediments at that point.

The diffusion behavior of the sediments can be roughlyinterpreted if it is assumed that bottom waters are at 2°Cand that room temperature conditions exist at depths ofabout 500 meters (temperature gradient of 4°C/100 m).Then for chloride ion, a diffusion coefficient of 3.4 × 10~6

is obtained for surficial sediments at Site 214 and a value of2.9 X 10-6 at 486 meters. The F factors increase from 2.9to 6.3 for the two intervals, and the smaller change incalculated diffusion coefficient for free solution would be1.0 and 2.0 × 105 for temperatures of 0°C and 25°C,respectively.

Making the same assumptions for Site 217, formationfactors of 2.5 and 13.6 at 7 and 547 meters depth,respectively, would yield diffusion coefficients of 4 × 10~6

cm2/sec and 1.5 × 10~6 cm2/sec. If temperature gradientswere steeper, the diffusion coefficients at depth would belarger. On the other hand, we may reckon that someartificial increase in the apparent diffusion coefficient iscaused not only by the presence of conductive clay,referred to earlier, but, by decompression of the sediments

665


30 25 20 15 10 5 0 °C

.20 .30 .40 .50 .60 .70 .80 .90 1.00

SPECIFIC RESISTIVITY IN OHMS

Figure 3. Graph for the determination of the temperature-corrected sediment resistivity.

2.00

when raising them to the surface. Nevertheless, the givenvalues may be regarded as providing a first approximationto diffusion coefficients for dissolved species at depth indeep-sea sediments. The preceding discussion has referredonly to the net diffusional velocity of free ions andmolecules in the pore spaces of the sediments. Wherereactive species are concerned, their reactions with hostsediments introduce further complications.

ACKNOWLEDGMENTSWe wish to thank Paul Mangelsdorf for reminding us of

the 4-electrode array and Donald Leblanc for constructingthe probes.

REFERENCES

Atlan, Y., Bardon, C, Minssieux, L., Quint, M., andDelvaux, P., 1968. Conductivite en milieu poreuxargileux. Interpretation des diagraphies. Troisiemecolloque de Fassociation de recherche sur les techniquesde forage et de production, 10-14 Juin, 1968, Pau.Comm. No. 31.

Jakosky, J. J., 1950. Exploration geophysics. NewportBeach, Calif. (Trija Publ. Co.).

Keller, G. V., 1969. Electrical resistivity measurements,Midway and Kure Atolls: U. S. Geol. Survey Prof. Paper,680-0.

Manheim, F. T., 1970. The diffusion of ions in uncon-solidated sediments: Earth Planet. Sci. Lett., v. 9, p.307-309.

Pirson, S. J., 1963. Handbook of well log analysis:Englewood, N. J. (Prentice Hall).

Smirnov, 1971. Proiskhozhdenie solenosti podzemnykh vodsedimentatsionnykh basseinov (On the origin of thesaline ground waters of sedimentary basins): Moscow("Nedra").

Waterman, L. S., 1970. Interstitial water program shipboardmanual: Deep Sea Drilling Project, La Jolla (ScrippsInstitution of Oceanography).

Zatenatskaya, N. P., 1965. Eksperimental'nye dannye podiffuzii solei v glinistykh porod v protsesse litogeneza(Experimental data on diffusion of salts in clayey rocks).In Strakhov, N.M. (Ed.), Postsedimentatsionnyeizmeneniya chetvertichnykh i pliotsenovykh glinistykhotlozhenii Bakinskogo arkhipelaga: Moscow (Nauka), p.143-159.

666


POROSITY CORRECTED FOR S=35.Z

.90 1.00

Figure 4. Water content versus porosity. The curve isdrawn assuming the relationship

Φ (porosity) =W

2.67

where W is water content, Wc is brine weight correctedfor salinity of 35.2 °/°°, obtained approximately bymultiplying W by 1.03, and 2.67 is the assumed graindensity of the sediments. For certain diatom- orradiolarian-rich samples, a separate claculation has beenmade, using the grain density of 2.4.

TABLE 1Resistivity Measurements, Site 212

Sample

212-2-3212-8-3212-10-5212-11-3212-16-2212-21-3212-23-3212-25-5212-27-5212-33-3212-35-2

Depth(m)

12130170196299321367389408464481

WaterContent

(%)

58.331.525.325.532.637.424.515.230.112.614.1

Porosity(%)

795548485561.54732.5542830

CorrectedPore Fluid

(Cell)

0.195(23)0.190 (24)0.195 (24)0.185 (24)0.205 (22)0.187 (24)0.182(25)0.189 (25)0.192 (25)0.190(25)0.191(25)

CorrectedReference

Fluid(Cell)

0.198 (24)0.190(25)0.190(25)0.188(25)0.188 (26)0.190(25)0.193 (25)0.193(25)0.194 (25)0.198 (25)0.198 (25)

ReferenceFluid(Cup)

0.301 (24)0.294 (25)0.316(25)0.316(25)0.296 (26)0.292 (25)0.292 (25)0.281(25)0.281 (25)0.290 (25)0.278 (25)

CellConstant

0.6580.6460.6010.5950.6720.6510.6610.6870.6900.6830.712

CorrectedSedimentResistivity

0.3980.7430.8830.7970.8201.0931.0581.8481.0912.2872.051

F

2.04.04.54.34.15.85.8

105.8a

12.510.7

Note: (19°11.3'S, 99°17.8'E) water depth 6243 m; 521 m penetration. Values in parentheses refer to temperatureof determination or correction basis. Cell refers to mini-cell. Cup refers to sediment container. All valuesexcept cell constant, are expressed in ohm-m. F refers to formation factor Rs/R\v (see text). Sediment con-sists of clayey nannoplankton ooze to 321 m, after which interlayered chalk and zeolitic clay occurred.Bottom two samples are chalk.

aThe consistent trend observed at this site suggests that this value is erroneous, possibly resulting from drillingdisturbance.

667



Sample

213-1-0213-2-5213-3-5213-5-5213-7-5213-9-6213-11-5213-13-6213-15-6213-16-4213-1-0213-3-5213-5-5

Depth(m)

< l1524446283

100121140146

< l2444

WaterContent

(%)

70687062696354543129

707062

Porosity(%)

878687808483767654.552.5878780

CorrectedPore Fluid

(Cell)

0.202 (22)0.199 (21)0.225 (15)0.223 (15)0.245 (13)0.270 (9)0.272(11)0.247(12)0.240 (14)0.193 (22)0.193 (24)0.185 (24)0.192 (22)

CorrectedReference

Fluid(Cell)

0.187 (27)0.186 (25)0.190(25)0.190 (25)0.193 (25)0.190 (26)0.196 (25)0.192(25)0.193(25)0.193 (25)0.195 (25)0.183 (27)0.186 (26)

ReferenceFluid(Cup)

0.266 (27)0.282 (25)0.279 (25)0.287 (25)0.281(25)0.280 (26)0.283 (25)0.283 (25)0.283 (25)0.282 (25)0.282 (25)0.276 (27)0.285 (26)

CellConstant

0.7030.6600.6810.6620.6870.6790.6930.6780.6820.6840.6910.6630.653


0.3280.3420.4240.4550.4180.6640.7830.6850.7090.6120.3440.3210.354

F

1.61.71.92.051.72.52.92.82.93.2

1.8al j a1.8a

Note: (10° 12.5'S, 93°53.8'E) water depth 5611 m; 172.5 m penetration. Notes as in Table 1. Sediments are clayeydiatom ooze to 64 m, zeolitic clay to 121 m, and nannofossil ooze below 121 m.

aMeasurements made on a continguous mini-core.


Sample

214-1-5214-3-5214-5-6214-7-5214-9-5214-11-5214-15-3214-19-5214-23-5214-27-5214-31-5214-35-5214-36-4214-37-221441-321446-3214-52,CC

Depth(m)

625446382

101136178216254292330338344384424486

WaterContent

(%)

44474344484243373224—-

31322536-

Porosity(%)

68706668716666615647-—

55564860-

CorrectedPore Fluid

(Cell)

0.201 (22)0.209 (20)0.226 (17)0.221 (16)0.214(17)0.233 (16)0.202 (21)0.216(17)0.256(11)0.250(13)0.208 (19)0.204 (20)0.199(22)0.210(19)0.210(21)0.254(11)0.192(21)

CorrectedReference

Fluid(Cell)

0.187 (27)0.196(25)0.196 (25)0.197 (24)0.192 (25)0.199 (24)0.197 (25)0.195 (25)0.192(25)0.196(25)0.195 (25)0.197 (24)0.199 (24)0.199 (24)0.188 (27)0.186 (27)

-

ReferenceFluid(Cup)

0.276 (27)0.284 (25)0.283 (25)0.286 (24)0.286 (25)0.289 (24)0.285 (25)0.284 (25)0.275 (25)0.275 (25)0.275 (25)0.277 (24)0.283 (24)0.285 (24)0.268 (27)0.262 (27)

-

CellConstant

0.6780.6900.6930.6890.6710.6890.6920.6870.6980.7130.7090.7110w7D30.6980.7010.7100.696

CorrectedSediment

Resistivity

0.5750.5690.6270.6080.5240.5920.5300.5660.7050.9270.7090.7401.0270.8381.4032.2501.204

F

2.92.72.82.72.52.52.62.62.83.73.43.75.14.06.78.96.3

Note: ( l l °20 .2 'S , 88°43. l 'E) water depth 1665 m; 500 m penetration. Notes as in Table 1. Sediments are foram-nanno ooze to 330 m, glauconitic calcarenite to 384 m, and clay pebble conglomerate to 486 m.

668



Sample

215-1-5215-3-5215-5-2215-8-3215-9-2215-10-2215-11-5215-13-3215-154

Depth(m)

6233868768599

115136

WaterContent

(%)

727274746734312827

Porosity(%)

868687.589.5855854.55150

CorrectedPore Fluid

(Cell)

0.235 (13)0.242 (13)0.252 (12)0.276 (9)0.260(11)0.235 (14)0.220 (17)0.221 (17)0.205 (20)

CorrectedReference

Fluid(Cell)

0.187 (26)0.197 (25)0.198 (25)0.192 (26)0.192 (26)0.192(26)0.191 (26)0.193 (26)0.192 (26)

ReferenceFluid(Cup)

0.270 (26)0.275 (25)0.273 (25)0.262 (26)0.262 (26)0.262 (26)0.262 (26)0.262 (26)0.262 (26)

CellConstant

0.6930.7160.7250.7330.7330.7330.7290.7370.733


0.3650.4210.4290.5860.5130.7090.6980.7170.7470.953

F

1.551.71.72.12.03.03.23.33.6a

4.7b

Note: (8°07.3'S, 86°47.5'E) water depth 5319 m; 175 m penetration. Notes as in Table 1. Sediments are radiolarian-diatom ooze to 38 m, silty zeolitic clays occur at 68-76 m. Below that depth nannoplankton oozes prevail.

a"Soft" end of mini-core.""Firm" end of mini-core.


Sample

216-1-6216-2-5216-4-5216-5-5216-64216-10-2216-14-3

Depth(m)

850

126164172208247

WaterContent

(%)

43403635333028

Porosity(%)

67646059575451

CorrectedPore Fluid

(Cell)

0.210 (20)0.223 (17)0.207 (20)0.192 (23)0.188 (24)0.195 (22)0.191 (22)

CorrectedReference

Fluid(Cell)

0.198 (25)0.199 (24)0.199 (24)0.197(25)0.196 (25)0.190 (26)0.188 (26)

ReferenceFluid(Cup)

0.272 (25)0.287 (24)0.293 (24)0.87 (25)0.287 (25)0.302 (26)0.295 (26)

CellConstant

0.7280.6930.6790.6860.6830.6290.637


0.7570.6300.5630.5530.5570.6420.956

F

3.62.82.82.92.93.35.0

Note: (1°27.7'N, 90°12.5'E) water depth 2247 m; 477.5 m penetration. Notes as in Table 1. Sediments areforaminifera-bearing nannoplankton ooze and chalk.


Sample

217-1-6217-2-2217-3-2217-4-4217-6-5217-8-5217-9-6217-104217-12, CC217-144217-16-4217-204217-30-3

Depth(m)

74272

120188274314348383397416454547

WaterContent

(%)

49434238312726242621202011

Porosity(%)

7266.565.56254.55049464941404025

CorrectedPore Fluid

(Cell)

0.198 (22)0.215 (18)0.230(15)0.218(17)0.227 (16)0.238 (12)0.192 (23)0.185 (24)0.183 (24)0.180 (24)0.177 (24)0.190 (22)0.178 (25)

CorrectedReference

Fluid(Cell)

0.202 (24)0.201 (24)0.199 (24)0.196 (25)0.201 (24)0.208 (23)0.200 (25)0.191 (25)0.195 (25)0.195 (25)0.196 (25)0.199 (24)0.192 (25)

ReferenceFluid(Cup)

0.304 (24)0.286 (24)0.284 (24)0.280 (25)0.287 (24)0.293 (23)0.283 (25)0.283 (25)0.287 (25)0.283 (25)0.283 (25)0.287 (24)0.289 (25)

CellConstant

0.6640.7030.7010.7000.7000.7100.7070.6750.6790.6890.6930.6930.664


0.5030.6490.6760.7280.7981.2071.6111.4580.8290.7861.8910.9432.432

F

2.53.02.93.33.55.08.37.94.54.4

10.75.0

13.6

Notes: (8°55.6'N, 90°32.3'E) water depth 3020 m; 614.5 m penetration. Notes as in Table 1. Sediments are clay-rich nannofossil ooze to 120 m, a nanno ooze chalk to 348 m, foram-rich chalk and chert to 416 m, andCretaceous micritic limestone to 547 m.

669



Sample

218-24218-3-2218-4-2218-5-2218-6-1218-8-3218-9,CC218-11-2218-13-2218-14,CC218-15-1218-16-2218-18,CC218-21-3218-22-2218-23-2218-24-2218-25-2218-26-2218-27-2

Depth(m)

8154372

110187232300376422452461488538575613651689727765

WaterContent

(%)

3631292940352332252319212118232119251720

Porosity(%)

605552.552.5645944.55647.544.53841413744.5413847.535.540

CorrectedPore Fluid

(Cell)

0.215(18)0.310(14)0.240(14)0.271 (10)0.239 (15)0.255 (13)0.233(16)0.198 (23)0.206 (20)0.189 (23)0.224(18)0.188 (23)0.189 (24)0.192(23)0.192 (24)0.187(23)0.211(20)0.221 (19)0.226(19)0.289 (9)

CorrectedReference

Fluid(Cell)

0.195 (24)0.199 (24)0.195 (24)0.201 (24)0.199 (24)0.198(24)0.199 (24)0.198 (24)0.199 (24)0.201 (24)0.195 (24)0.187(25)0.190(25)0.192(25)0.191 (25)0.190(25)0.194 (25)0.198 (24)0.199 (24)0.194 (24)

ReferenceFluid(Cup)

0.283 (24)0.284 (24)0.283 (24)0.277 (24)0.277 (24)0.277 (24)0.277 (24)0.281 (24)0.279 (24)0.291 (24)0.282 (24)0.266 (25)0.266 (25)0.266 (25)0.266 (25)0.269 (25)0.283 (25)0.286 (24)0.267 (24)0.281 (24)

CellConstant

0.6890.7010.6890.7260.7180.7150.7180.7050.7130.6870.6910.7030.7140.7220.7180.7060.6860.6920.7450.690


0.6410.9321.0201.0440.8620.9221.3510.6311.3771.2301.1271.1671.4071.0610.9911.3001.6381.0731.8781.3601.498

F

3.03.04.33.83.63.75.83.26.86.55.06.257.55.55.26.87.94.88.36.0a5.3a

Note: (8°00.4'N, 86°17.0'E) water depth 3759 m; 773 m penetration. Notes as in Table 1. Sediments are sandy toclayey silts with interspersed nanno ooze.

aTwo irregular shaped pieces were taken from this core.

100

ExchangeMeg/lOOg

1

3

10

20

40

70

100

Capacity

VΔD

OX

••

9 100 P (%)

Figure 5. Relationships between formation factor, porosity, and exchange capacity for various sediments. Drawnfrom data in Atlan et al, 1968. Conductivity of thepermeating solution (NaCl) is 15 mho/m.

670

Documents

32. Diffusimetry (Diffusion Constant Estimation)