A new mechanism for pressure solution in porous quartzose sandstone

0016-7037/87/$3.00

Grnchrmrco er Co.vmxhrmlca Acta Vol. 5 I, pp. 2295-2301 0 Pergamon Journals Ltd.1987. Printed in U.S.A.

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A new mechanism for pressure solution in porous quartzose sandstone RYUJI TADA’, ROBERT MALIVA’ and

RAYMOND

SIEVER’

‘Geological Institute, University of Tokyo, 7-3-I Hongo. Tokyo 113, Japan 2Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02 138. U.S.A (Received March 11, 1986; accepted in revised-form June 8. 1987)

Abstract-The mechanism of pressure solution, a source of controversy for years. must be understood before we can evaluate the effectiveness of pressure solution during geological processes. The water film diffusion (WFD) mechanism proposed by WEYL (1959) and RUI-TER (1976, 1983) is believed by many to be the primary mechanism responsible for intergranular pressure solution (B’S) in non-porous metamorphic rocks as well as porous sedimentary rocks. TADA and SIEVER (1986), experimenting with halite single crystals, suggested the new plastic deformation plus free-face pressure solution (PD + FFPS) mechanism. The effectiveness of PD + PFPS as an IPS mechanism is theoretically evaluated for porous quartzose sandstone and compared with WFD. The result suggests that, though the driving force of the reaction (relative activity increase) is 4 to 5 orders of magnitude larger in WPD, the ease of diffusion (diffusion path width times the diffusion coefficient) is 7 to 9 orders of magnitude larger in PD + PIPS. Consequently. PD + FPPS yields diffusion rates 2 to 5 orders of magnitude faster than WFD. In WPD, diffusion is always the rate-controlling process, whereas either dissolution at IPS contacts or precipitation on free grain surfaces may be the rate-controlling process in PD + FFPS, when temperatures are low and/or grain sizes are small. The dissolution or precipitation rate of PD + FFPS is faster than the diffusion rate of WFD except when the total free grain surface area is very small. In final stagesof compaction, when the total free grain surface area has become very small, WFD replaces PD + FFPS. INTRODUCTION

PRESSURESOLUTION,especially intergranular pressure solution (IPS), is important as one of the main mechanisms for compaction and cementation in porous sedimentary rocks (TADA and SIEVER, 1987), as well as a mechanism for deformation of non-porous sedimentary rocks and low-grade metamorphic rocks (RUTTER, 1976; MCCLAY, 1977). The effectiveness of pressure solution as a compaction and cementation mechanism is poorly understood. Few have treated the phenomenon quantitatively and rates and rate-controlling factors have not been adequately explored. Newer petrographic studies using cathode-luminescence techniques have added to our knowledge of the extent of IPS (SIBLEY and BLATT, 1976; HOUSEKNECHT, 1984). Although compaction experiments have been designed to determine the rates (RENTON et al., 1969; DE BOER et al., 1977; SPRUNT and NUR, 1977), the experiments were of limited value because they (1) used much higher temperatures and pressures than those of diagenetic conditions; (2) did not eliminate or evaluate the effect of other compaction mechanisms such as grain reorientation, fracturing, and deformation; (3) did not measure the amount dissolved due to IPS; and most of all, (4) could not specify the mechanism operating at the grain contacts. Knowledge of the operating mechanism is crucial to a study of the rates and rate-controlling factors of IPS. Basically two mechanisms have been previously proposed to explain IPS: (1) the water film diffusion (WPD) mechanism which assumes dissolution at loaded-faces followed by diffusion through a thin water film within the grain interface (WEYL, 1959; RUTTER, 1976, 1983); and (2) the undercutting mechanism, which advocates free-face dissolution at the periphery

of the contacts followed by grain crushing within contacts (BATHURST, 1958; WEYL, 1959; OSTAPENKO, 1968). WPD has a better established theoretical background (RUTTER, 1976) and its inferred driving force is much larger (DE BOER, 1977; ROBIN, 1978) than the undercutting mechanism. WFD is consistent with creep test data for non-porous aggregates of potassium carbonate and kaolinite (RUTTER, 1983) and can be applied to non-porous rocks. But even in non-porous aggregates, convincing evidence of WFD has yet to be reported. Observation of the detailed textures of IPS contacts gives useful information on the operating mechanism, such as the site and mode of dissolution. TADA and SIEVER( 1986) designed knife-edge pressure solution experiments using halite single crystals in order to observe the detailed texture of a pressure solution contact. Based on their observations, they proposed the plastic deformation plus free-face pressure solution (PD + FFPS) mechanism. PD + PFPS is similar in some ways to the undercutting mechanism, except for the inference of steadystate plastic deformation within the contacts instead of catastrophic grain crushing. PD + FFPS can be actually observed in the laboratory and has a sound theoretical basis (TADA and SIEVER, 1986). Whereas the undercutting mechanism has some ambiguity in its kinematics, the kinematics of PD + FFPS is very clear. Because the knife-edge experiment was conducted under relatively low temperature and stresses in a large volume of aqueous solution, it is reasonable to apply PD + FPPS to porous rocks under diagenetic conditions. PD + FFPS has been experimentary tested only for halite. To extend the mechanism to a much commoner and less soluble mineral of sedimentary rocks. we

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R. Tada, R. Maliva and R. Siever

2296

compare below the rate of pressure solution for quartz deduced from PD + FFPS with that deduced from WFD.

(2) (1)

I':':':',"~"~:"~"~"~"~"~"~"~"~"~"~:

THE TWO MECHANISMS FOR IPS

Water film diffusion

WFD was originally proposed by WEYL (1959) as a mechanism for pressure solution in porous quartzose sandstone. Later, RUTTER (1976) gave the rate equation for non-porous aggregates based on this mechanism. His equation suggests that WFD is similar to grain-boundary diffusion creep (COBLE, 1963), although Rutter assumed the diffusion media to be thin water film on grain surfaces instead of grain-boundaries. WFD assumes dissolution at grain interfaces subjected to an applied normal stress (loaded-faces) and the presence of a thin water film within grain interfaces which can support the applied stress. The dissolved material is considered to diffuse through the water film to pore spaces (Fig. 1). Plastic deformation plus free-face pressure solution

PD + FFPS proposed by TADA and SIEVER (1986) can be regarded as a modification of the undercutting mechanism. The outline of this mechanism follows. (1) Free-face pressure solution starting from the edge of a contact gradually decreases the true contact area, which supports the applied stress, until the yield stress is reached there. (2) Once the yield stress is reached, plastic or, in some materials, brittle deformation starts under the true contact. (3) Deformed material is extruded, thus exposed as a free-face on the side wall of the true contact. There the plastically strained freeface is dissolved, keeping the true contact area constant. (4) Dissolution also occurs on the free-face in the immediate neighborhood of the true contact due to an elastic strain. This dissolution keeps the intergranular contact distance of the two grains constant (Fig. 2). Because free-face dissolution due to elastic strain is restricted to the neighborhood of the true contact, a multi-contact system would be predicted, not a singiecontact system. This system affords a more homogeneous distribution of elastic strain throughout the freeface within the apparent contact area (Fig. 3). This is

FIG. I. Schematic illustration of the water film diffusion mechanism after WEYL (1959). Dissolution occurs on loadedfaces (thick lines) and dissolved material diffuses through a thin water film (shaded area) which can support the deviatoric stress normal to the grain interface (un - Pl.

(4)

FIG. 2. Schematic illustrations of the plastic deformation plus free-face pressure solution mechanism after TADA and SIEVER (1986). (1) Dissolution (sites are represented as thick lines) starts on free-faces at contact edges. (2) The yield stress is reached on the true contact (shaded area). (3) Plastic deformation starts below the true contact and deformed material is extruded and exposed on the side wall. There the plastically strained free-face is dissolved, keeping the true contact area constant. (4) Dissolution also occurs on the free-face in the immediate neighbourhood of the true contact, which keeps the intergranular contact distance constant.

especially so when the average normal stress on the apparent contact is much smaller than the yield stress and the true contact area becomes much smaller than the apparent contact area. COMPARISON OF THE RATES OF IPS BY THE TWO MECHANISMS

Both WEYL (1959) and RUTTER (1976, 1983) assumed diffusion through the water film to be the ratecontrolling step ofIPS in WFD because of the obviously low value of the diffusion coefficient within a very thin water film. This may not necessarily be the case for PD + FFPS. A comparison of the diffusion rates given by the two mechanisms shows the effectiveness of PD + FFPS. Diffusion rate equation

Generally, the diffusion flux of dissolved material in one dimension can be given by Fick's first law

FIG. 3. Schematic illustration of multi-contact system for the plastic deformation plus free-face pressure solution mechanism. Dissolution occurs on free faces (thick lines) within the apparent contact, while plastic deformation occurs at multi-contacts (shaded area).

2297

Pressure solution mechanisms

J=

_*dc

(4)

G!x

where J is the flux of the solute, D is its diffusion coefficient, and ;i;; dc IS its concentration

gradient. In the

case of WFD, ROBIN ( 1978) and RULER ( 1983) suggested a rewritten Fick’s first law: J =

-Mg’

where A4 is a phenomenological diffusion and g

J= -2mwD

$ i

constant related to

is the chemical potential gradient of

the solute. Equation (2) is reasonable since the chemical potential gradient is the true driving force of pressure solution and should be used instead of Eqn. (1) when the pressure within a water film is not uniform (ROBIN, 1978). Although Eqn. (2) is better used than (1) to calculate diffusion rates given by WFD, no measurement of M is available. RUTTER ( 1983) estimated M as about 10mz2 81. units (J-’ m-’ set-’ mole2), his estimation being based on calculations working backwards from strain rate data of a creep test. In his calculations, he assumed the creep to be caused by WFD. However, neither direct evidence nor convincing supporting evidence was presented that would justify WFD as the unique mechanism to explain the creep. For this reason, we believe it is not appropriate to use his estimated value in this discussion. Alternatively, we introduce the hypothetical activity (a*) defined as a* = e-p

where a is the actual activity of the solute and p* is the chemical potential of pure solute at temperature T and pressure (T, Based on Eqn. (1) the diffusion flux from a circular contact of radius r is given by

(Ek$ )

where ps is the chemical potential of the solid under the deviatoric stress within the diffusion path, & is the chemical potential of the pure solute at temperature T and pore water pressure P, and R is the gas constant (DURNEY, 1972; PATERSON, 1973; DE BOER, 1977). The chemical potential of the solid is used instead of that of the solute because the solution is in equilibrium with the adjacent solid under the deviatoric stress within the diffusion path in the case of a diffusioncontrolled process. The hypothetical activity is equivalent to the activity of the solute in solution whose pressure is P and is in equilibrium with the adjacent solid under the deviatoric stress. With this hypothetical activity, it is possible to convert the chemical potential difference to the activity difference and calculate the diffusion flux using Eqn. (1). In PD + FFPS, the hypothetical activity is equal to the actual activity of the solute in solution because the pressure of the solution is a constant P throughout the diffusion path. It is different from the actual activity in WFD because the pressure within a water fiIm should be equal to the stress normal to the interface (a.) (ROBIN, 1978) in which case

1x-r

(5)

where n’ is the thickness of diffusion path and da* is the hypothetical activity gradient at the pe= i ) x=r is proportional to riphery of the contact. The $$ ( ) X’T Au*. This is the difference between the hypothetical activity of the solute in equilibrium with the solid within the interface under the average stress 5, and the activity of the solute in equilibrium with strainfree free-faces under pore water pressure P. Aa*=a*-a,.

(6)

At a given contact radius, the diffusing flux is proportional to the product of w, D and Aa*. Diffusion path width (w) The WFD model assumes a thin water film within the grain interface as a diffusion path. This thin water film has to support the deviatoric stress normal to the grain interface (WEYL, 1959; RUTTER, 1976, 1983). The equilibrium force required to remove a small increment of thickness of thin liquid layer is known as disjoining pressure (rr) (PADDAY,197 1), which balances the normal stress. Disjoining pressure can be obtained from the vapor pressure (P.,) in equilibrium with the thin film of known thickness through the equation *=--_lnRT vm

-P, 0Ps

where V,,,is the molar volume of the substance forming the thin layer, and P, is the saturated vapor pressure (PADDAY, 1971). Figure 4 shows the relationship between the disjoining pressure and water film thickness for flat silica surfaces based on the data from PASHLEY and KITCHENER( 1979) and ILER ( 1979, p. 630). As is obvious from Fig. 4, the disjoining pressure increases drastically with a decrease in the water film thickness below 3 nm. This high disjoining pressure is probably due to the change in free energy of the thin layer caused by orientation, solvation or other specific interactions between the solid and the thin water film. In contrast, the lower disjoining pressure of a thicker water film (>3 nm) is due to electrostatic pressure (PADDAY, 1971). Water first adsorbs on a silanol surface by hydrogen bonding with a bond strength of 8 to 12 KJ mol-’ until a continuous network of water molecules covers the surface (ANDERSON and WICKERSHEIM,

R.Tada, R. Maliva and R. Sever

2298

1984). Thus, the diffusion path width for PD t FOPS is within the range of 10 nm to 1 rrn and qutte likeiy of the order of 100 nm. DiJiision coejicient (Dj

J--.-__0 5

WATERFILMTHICKNESS

10

___i fnm)

FIG. 4. A diagram showing the relationship between disjoining pressure and water film thickness for distilled water film on 5at silica surfaces based on the data of PASHLEY and KITCHENER (1979) (0) and ILER (1979) (0).

1964; ANDERSON, 1965), followed by physically adsorbed water (ILER, 1979, p. 630). Using the concentration of hydroxyl groups on a silica surface of 5 OH nmw2 (ILER, 1979, pp. 630-637) and the hydrogen bond strength of 10 KJ mol-’ (ANDERSON,1965), the energy of hydrogen bonding is calculated as 0.083 J m-’ at the silanol surface. Assuming a water monolayer thickness of 0.31 nm, disjoining pressure for the first monolayer of the water is calculated at 270 MPa, which is in good agreement with the value obtained from the vapor pressure data (Fig. 4). Repulsion of the electric double layer, which probably contributes to the disjoining pressure of a thicker water film (>3 nm) is also able to support a certain amount of normal stress but the value may not exceed 10 MPa (Fig. 4). Moreover, the thickness of the electric double layer decreases with an increase of electrolyte concentration (YARN and CROSS, 1979), and its thickness is only about 1 nm in 0.1 M NaCl solution (PARKS, 1984). In most sedimentary rocks, pore water is more or less saline, and the contribution of electrostatic pressure may be small compared to the contribution of adsorption of water molecules on the surface that supports the normal stress at grain contacts. Thus. the diffusion path width for WFD is probably less than 3 nm, and it depends on the normal stress. PD + FFPS requires the presence of liquid water within the grain interface system. This water does not have to support the deviatoric stress, since the stress is supported by small knobs or ridges within the interface. In order to maintain liquid water properties, the distance between the two grains forming the interface should be larger than 10 nm. SEM observation of IPS contacts suggests that the distance is less than 1 pm (MURPHY, 1984; AUCREMANN, 1984), and that microcanals of a few hundred nm in width were formed between subgrains within the interface (WELTON.

The diffusion coefficient for silica withm the thm water film (~3 nm) postulated for WFD must be much smaller than the diffusion coefficient m bull, water. because water molecules within the thin film arc strongly adsorbed on grain surfaces. RLVTER ( 19763 estimated the diffusion coefficient in a 2 nm thick water film to be around lo-l4 mz set-’ based on consideration of the electroviscous effect (ELTON, 1948). But the effect of adsorption dominates over the electrostatic effect within a water film of several monolayers thick (PADDAY, I97 1). Consequently, the diffusion coefficient for a <3 nm thick water film must be smaller than the estimated value of Rutter. ADAMSef al. ( 1983) studied the exchange of D20 for H20 in the interlayer of a montmorillonite with a spacing of 2.33 nm, using neutron diffraction techniques. They estimated the diffusion coefficient to be around lo-l6 m’ set-’ in the temperature interval 298 to 328°K. This value seems to be the closest to the ditision coefficient in an adsorbed water film several monolayers thick. The diffusion coefficient probably decreases with decreasing water film thickness. In the case of PD + FFPS, the diffusion coefficient in the water “film” within the grain interface ( 100 nm thick) is close to that in bulk water. When the electrolyte concentration of the water is low, the effect of electroviscosity should be taken into account and the coefficient will be as small as lo-” mz set-‘. But with an increase of electrolyte concentration, the effect of electroviscosity will decrease and the coefficient will become close to loo9 m2 set-‘. the value in butk water. The activity dtyerence (Aa*J The activity difference, Aa*, IS defined m hqn. (6). The hypothetical activity of the solute in equilibrium with the elastically strained loaded-faces under the normal stress (a:), and the activity of the solute in equilibrium with the elastically strained free-faces parallel to the applied stress (a/*) are both given by PATERSON (1973) in his Eqns. (15a) and (15b), respectively. Using his equations, we can calculate the relative * activity increase, which is defined as lla (DE BOER. a,, 1977). As is shown in Fig. 5, the relative activity increases when the solid is strained only elastically is lo-’ to IO4at the loaded-faces. This is 4 to 5 orders of magnitude larger than the figures of 1O-’ to IO ’ at the free-faces under deviatoric stresses ranging from 1 to 1000 MPa. Permanent strain energy may also cause an activity increase. This component of the activity increase may be significant, especially on free-faces (E&WORTH, 198 1). WINTSCH and DUNNING (1985) studied the effect of dislocation density on quartz solubiiity. Ac-

Pressure solution mechanisms

27-99

Diffusion rate by the two mechanisms Based on the estimation of diffusion path widths. diffusion coefficients, and activity differences described above, the diffusion rates given by the two mechanisms can be calculated. As is shown in Table 1. the activity difference is 4 to 5 orders of magnitude larger for WFD. But the diffusion path width and diffusion coefficient are 2 and 5 to 7 orders of magnitude larger, respectively, for PD + FFPS. Consequently, when the dissolving solid is strained elastically only and pore water is in equilibrium with the strain-free quartz surface, the diffusion rate is 2 to 5 orders of magnitude faster for PD + FFPS. If the free-faces are permanently strained, the diffusion rate for PD + FFPS is even faster. The result of the above calculations strongly suggests that PD + FFPS is more effective as an IPS mechanism than WED when diffusion is the rate-controlling process. DEVIATORICSTRESS Pn- P (MPa) Petrographic evidence also supports PD + FFPS. FIG. 5. A diagram showing the relative activity increase for PITTMAN (1972) showed that IPS contact surfaces in loaded-faces and free-faces of elastically strained quartz with quartzose sandstone are generally irregular and comincreasing deviatoric stress. Calculation is based on PATERSON's( 1973)Eqns.(ISC)and ( I5d). Values used are as follows: posed of ridges and furrows or knobs and pits. WFD R = 8.3144 J mall’ OK-‘, E = 1.1 X 10’ MPa, K = 0.38 cannot explain these irregular surfaces, whereas they X 10’ MPa, V = 22.69 X IO6m3 mol-‘, P = 30 MPa, T are consistent with PD + FFPS (TADA and SIEVER. = 300°K (solid lines) and 600°K (broken lines). The relative 1986). In addition, HOUSEKNECHT(1984) and TADA activity increase is rather insensitive to pore water pressure (P). Relative activity increasesdue to dislocations with density and SIEVER(I 987) showed that IPS and quartz cement of 10” me2 at 400°K after WINT~CH and DUNNING(1985) amounts usually do not balance and tend to show a (line A) and due to microgranulation with grain diameter of mutually exclusive relationship in quartzose sand100 nm (line B) are also shown. stones, suggesting that silica was removed where IPS was intense and precipitated where IPS was weak. HOUSEKNECHT(1984) further showed that finer sandstones tend to be a silica exporter, whereas coarser cording to their data, dislocations with a density of sandstones tend to be an importer. If diffusion through I013me2 will cause a relative activity increase of about the water film is the rate-controlling step, as is assumed IO-‘, which is larger than the increase caused by elastic in WFD, the silica diffused out of the contacts would strain on free-faces at deviatoric stresses below 100 tend to precipitate within the system. The above obMPa. According to them, dislocation densities of as servation indicates, however, that the system was not much as lOi mm2 is not rare in nature. closed during IPS. WPD is not consistent with this In addition, an increase in surface area at the contacts petrographic observation. PD + FFPS, however, does due to microcracking and microgranulation may cause explain this differential pressure solution-reprecipitaa significant increase in free energy (OSTAPENKO,1968, tion phenomena (TADA, 1987). 1975; ENGELDER, 1982). SEM observations on IPS contacts in quartzose sandstone by WELTON ( 1984, p. KINETICS OF II’S BY PD + FFPS 10) show evidence of microgranulation with subgrain sizes of the order of 100 nm in diameter. In our labIPS is a sequential process of dissolution at grain oratories we compacted quartz sand under a piston contacts, diffusion through the grain interface and prepressure of 30 MPa, a fluid pressure equal to vapour cipitation on free grain surfaces, the slowest process of pressure, a temperature of 4 13°K and initial loading which becomes the rate-controlling process. As discussed above, diffusion rates are relatively fast in PD rate of 5 MPa/day. Under the SEM we found small particles, less than 100 nm in diameter, on IPS contacts. + PEPS, so the assumption that diffusion is exclusively We also observed an increase in quartz solubility up the rate-controlling process may not hold. TADA (1987) has calculated and compared dissoto 25% higher than the equilibrium solubility of quartz. Using the Ostward-Freundlich equation with the inlution rates at grain contacts (vs), diffusion rates through terfacial free energy of the quartz-water interface as the grain interface (vd) and precipitation rates on free 360 mJ m-* after PARKS ( 1984) and a temperature of grain surfaces (v,) of PD + FFPS in porous quartzose sandstones. The results of his calculations show that 413”K, the particle diameter that causes a 25% solueither v, or ~2 becomes the slowest when grain size is bility increase is calculated to be 40 nm, which is consistent with the results of SEM observation. The solsmall and/or temperature is low, whereas vd becomes the slowest when grain size is large and/or temperature ubility increase caused by quartz particles 100 nm in is high (Fig. 6). Whether v, or v, becomes the slowest diameter is about 10%.

R. Tada, R. Maliva and R. Siever

2300 Table 1. coefflclent product mechanism. between

t

1

Comparison of dlffuslon [Dl, relative actlvlty Aa+wD/a 1 betkeen the and

Tempepature 1000 HPa.

15

ca.

WFD w

(

m

D

(rn’se~-~~

mechan

tm3sece1)

devlatorlc

pressure

1 sm

PD*FFPS

4

lo-?i”

I_

1 0 _7_ -21

at low temperatures and/or small grain sizes depends on the degree of compaction. When the sandstone is only slightly compacted, grain contact area is much smaller than free grain surface area and v, is the slowest. When the sandstone is moderately to well compacted, the free grain surface area is much smaller and vp is the slowest. Regardless of whether dissolution or precipitation is the rate-controlling process, both of these rates are higher in PD + FFPS than the diffusion rates given by WFD in quartzose sandstones. A sole excep tion occurs when the area of grain contacts or free grain surfaces is very small. Thus, PD + FFPS is generally more effective than the WFD mechanism even when diffusion is not the rate-controlling process in PD + FFPS. At the beginning of compaction, when the grain contact area is very small, indentation may occur instead of IPS and dissolution due to permanent strain may be espcially important (GREEN, 1984). Only at the final stages of compaction, when the free grain surface area is very small, will WFD be more effective than PD + FFPS. CONCLUSIONS Previous authors tend to have looked only at the size of driving forces of pressure solution but the mechanism with the largest driving force is not necessarily the most effective. The driving force for WFD is 4 to 5 orders of magnitude larger than that for PD

IS

mechanism

-7

]()-I

,o‘2-.

Aa*vD/a”

and

dlffuslon 1 and the] 1. ‘the PD+FFPS

1~1.

[Aa*/a and

I II

IO-l6

Aa*/ap

width

~nclease WFD mechanism

3OO’K.

10-q

1

path

I0 -252

-9

_] -17

+ FFPS, but the ease of diffusion represented by the product of diffusion path width and the diffusion coefficient is 7 to 9 orders of magnitude larger for PD + FOPS. Consequently, diffusion rates for PD + FFPS are 2 to 5 orders of magnitude larger than for WFD when diffusion is the rate-controlling process. Dissolution at the contacts or precipitation on free grain surfaces can be the rate-controlling process in PD + FFPS when temperature is low and/or grain size is small. However, even when dissolution or precipitation is the rate-controlling process in PD + FOPS, these rates are still faster than the diffusion rate for WFD. Thus, it is concluded that PD + FFPS is more likely responsible for IPS in porous quartzose sandstone than WFD. Petrographic evidence such as the irregular morphology of IPS contact surfaces (PITTMAN, 1972; WELTON, 1984) and differential pressure solution-cementation phenomena (HOUSEKNECHT, 1984; TADA and SIEVER, 1987) observed in quartzose sandstones also supports PD + FFPS rather than WFD. This conclusion is probably applicable to sedimentary rocks other than quartzose sandstones. Acknowledgements-The

major part of this work was done with support of NSF grant EAR 82- 12261while R. Tada was a post-doctoral fellow in the Department of Geological Sciences at Harvard University under the auspices of the Japanese Society for Promotion of Science from 1983 to 1985. We express our sincere thanks to Drs. S. Karato. W. Bosworth. and A. Iijima for their reading an early version of the manuscript.

Editorial handling: T. Pares

REFERENCES DIFFUSION

i

a g

\

\‘.\

loo-

if

CONTROLLED 1

\ 1~

DISSOLUTION OR

PRECIPITATION

\\ \

CONTROLLED

0

‘\,

, lo-’

lo+ GRAIN

10

-2

SIZE (ml

FIG. 6. A diagram showing the rate-controlling step of IPS in quartzose sandstone in relation to temperature and grain size. The boundary position is also a function of the degree of compaction. The wD value is assumed as IO-l6 m3 set-’ (line A) and IO-‘* m3 set-’ (line B).

ADAMSJ. M., BREENC. and RIEKELC. ( 1983) Deuterium/ hydrogen exchange in interlamellar water in the 23.3 A Na+-montmorillonite: pyridine/water intercalate. II. Activation energies. J. Co/&d Inte$xe Sci. 94, 380-387. ANDERSONJ. H. (1965) Calorimetric vs. infrared measures of adsorption bond strength in silica. Surfice Sci. 3, 290291. ANDERSONJ. H. and WICKERSHEIMK. A. (1964) Near infrared characterization of water and hydroxyl groups on silica surfaces. Surface Sci. 2, 252-260. AUCREMANNL. T. (1984) Diagenesis and porosity evolution of the Jurassic Nugget Sandstone, Anschutz Ranch East Field, Summit County, Utah. Master’s thesis, Univ. of Missouri. BATHURSTR. G. C. (1958) Diagenetic fabrics in some British Dinantian limestones. Liverpool Manchester Geol. J. 2, I l36.

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