Crystal-mush compaction in the Cohassett flood-basalt flow, Hanford, Washington

The degree of compaction, as determined from variations in the amount of interstitial liquid and quantitative measures of textural anisotropy, accounts for the chemical variation through the central part of the flow, with compatible elements being concentrated in the lower part of the flow and incompatible elements concentrated in the upper part. Modeling of the compaction process using the IRIDIUM melt infiltration and reaction program of [Boudreau, A., 2003. IRIDIUM: a program to model reaction of silicate liquid infiltrating a porous solid assemblage. Computers and Geosciences 29, 423-429] shows that the observed chemical and compaction/dilation profiles are to be expected in a 40-m-thick sheet of basaltic magma solidifying on the Earth's surface. Compaction of crystal mush should be even more likely in slowly cooled intrusive bodies.