Shock Effects in Carbonate Minerals and Rocks.
Abstract
The ESR spectra of Mn(++) in naturally and laboratory shocked calcite crystals and coral core samples were studied and variations in several spectral parameters were found to be correlative with shock pressure. The amount of splitting in the central transition hyperfine component peaks was observed to decrease in the upper levels of the Cactus Crater core and in core samples shocked in the laboratory to progressively higher pressures. A comparison of the splitting amplitude between the two types of samples allows pressure assignments to the Cactus core of 3.3 GPa at 8m. + or - 5m. and 2.0 GPa at 13m. + or - 5m. Unshocked coral core samples showed no splitting amplitude variation with depth. Results from coral subjected to a long duration pressure pulse in the Miser's Bluff TNT experiment are generally inconsistent. Laboratory shocked single crystal calcite showed similar decreases in hyperfine peak splitting but at pressure levels three times greater than those producing comparable coral sample spectra. The decrease in peak splitting is interpreted to reflect small increases in cation-anion distances produced by mechanical energy input during the shock process. Another parameter, the non-central to central transition peak amplitude, is observed to decrease with increasing pressure in spectra of single crystal calcite, and may provide a means of empirically correlating very low (less than 4.5 GPa) shock pressure levels in calcite. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 30, 1978
- Accession Number
- ADA071372
Entities
People
- Joana Vizgirda
- Thomas J. Ahrens
Organizations
- California Institute of Technology