Significant effect of grain size distribution on compaction rates in granular aggregates

André Niemeijer, Derek Elsworth, Chris J. Marone

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

We investigate the role of pressure solution in deformation of upper- to mid-crustal rocks using aggregates of halite as a room temperature analog for fluid-assisted deformation processes in the Earth's crust. Experiments evaluate the effects of initial grain size distribution on macroscopic pressure solution rate of the aggregate and compare the results to theoretical models for pressure solution. We find that the grain size exponent deviates significantly from the theoretical value of 3 for diffusion-controlled pressure solution. Models typically assume mono-dispersed spherical particles in pseudo-regular packing. We infer that the discrepancy between experimentally determined grain size exponents and the theoretical values are a result of deviation of experimental (and natural) samples from regular packs of mono-dispersed spherical particles. Moreover, we find that compaction rates can vary by up to one order of magnitude as a function of the width of the grain size distribution for a given mean grain size. Wider size distributions allow for higher initial compaction rates, increasing the macroscopic compaction rate with respect to more narrow grain size distributions. Grain sizes in rocks, fault gouges, and hydrocarbon reservoirs are typically log-normal or power law distributed and therefore pressure solution rates may significantly exceed theoretical predictions. Spatiotemporal variations in pressure solution rates due to variations in grain size may cause the formation of low porosity zones, which could potentially focus deformation in these zones and produce pockets of high pore pressures, promoting nucleation of frictional instability and earthquake rupture.

Original languageEnglish (US)
Pages (from-to)386-391
Number of pages6
JournalEarth and Planetary Science Letters
Volume284
Issue number3-4
DOIs
StatePublished - Jul 15 2009

Fingerprint

pressure solution
compaction
Compaction
grain size
Rocks
Pore pressure
exponents
rocks
Sodium chloride
Hydrocarbons
porosity
fault gouge
Earth crust
earthquake rupture
rate
effect
hydrocarbon reservoir
Earthquakes
halite
Nucleation

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

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Significant effect of grain size distribution on compaction rates in granular aggregates. / Niemeijer, André; Elsworth, Derek; Marone, Chris J.

In: Earth and Planetary Science Letters, Vol. 284, No. 3-4, 15.07.2009, p. 386-391.

Research output: Contribution to journalArticle

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