Shock Propagation In Crustal Rock
Abstract
New equation of state data for a weathered granite shocked to about 125 GPa are reported and combined with the Westerly granite data of McQueen et al. The shock velocity (U sub s)-particle velocity (U sub p) relations can be fit with two linear regressions: U sub s = 4.70 + 0.46 U sub p in a range of U sub p from 0.7 to about 2 km/sec and U sub s = 2.66 + 1.49 U sub p in a range of about 2 to 5 km/sec. From measurements of partially released states in granite, it is proposed that the high-pressure forms of tectosilicates, including granite, relax isentropically to a metastable, intermediate phase characterized by dense (about 3.7 g/cc), highly-disordered, six-fold coordinated phase which is subsequently quenched to diaplectic glasses of density approx. 2.3 g/cc), starting at pressure of approx. 10 GPa. We develop an analytical model to describe the release isentropes in the mixed phase regime which prescribe release to a glass phase with increasing transformation to the high pressure phase. Hugoniot and post-shock energies and temperatures derived from the release isentropes are consistent with available data and theoretical expectations for quartz and granite. Shock wave data for equation of state of muscovite (initial density=2.835 g/cc) was determined up to a pressure of 141 GPa. Observed unloading paths from shock pressures up to about 80 GPa are steeper in a density-pressure plane than the Hugoniot, and becomes shallower with increasing shock pressure above that pressure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 29, 1991
- Accession Number
- ADA239548
Entities
People
- Allan M. Rubin
- Thomas J. Ahrens
- Thomas S Duffy
- Toshimori Sekine
Organizations
- California Institute of Technology