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State of stress and relationship of mechanical properties to hydrothermal alteration at Valles Caldera core hole 1, New Mexico

1988; American Geophysical Union; Volume: 93; Issue: B6 Linguagem: Inglês

10.1029/jb093ib06p06108

2156-2202

Thomas Dey, Robert L. Kranz,

Hydraulic Fracturing and Reservoir Analysis

We measured the densities, total and microcrack porosities, and ultrasonic velocities of a number of core samples from an 856‐m‐deep core hole near the Banco Bonito vent at Valles Caldera, New Mexico. Reductions in porosity with depth define a zone from about 600 m down where hydrothermal mineralization and recrystallization have been most active. This zone is also reflected in a large decrease in the anisotropy of acoustic velocities. Stress orientation estimates based on microcrack orientations at the 812‐m depth as determined by differential strain curve analysis, as well as anelastic strain recovery measurements on a sample from 472‐m depth, show a horizontal E‐W minimum compression direction and a maximum compression inclined about 30° from vertical.