A REVIEW OF THE STRUCTURE, PETROLOGY, AND DYNAMIC DEFORMATION CHARACTERISTICS OF SOME ENIGMATIC TERRESTRIAL STRUCTURES

We review three categories of enigmatic terrestrial structures that have a variety of macroscopic and microscopic dynamic deformation features. The first category includes the Midcontinent, United States cryptoexplosion structures. They are of shallow origin and illustrate the effects that might be expected from a meteorite impact on a sedimentary rock terrane. The second category includes the well known Vredefort and Sudbury plutons or basement uplifts; the lesser known Precambrian basement uplifts at Steen River, Manson, and Carswell; and the diatreme breccia dikes at the Slate Islands. They are of relatively deep seated origin and illustrate the effects that might be expected from deep crustal or mantle processes of an explosive nature. The third category includes the large landslides in areas of crystalline rocks at Koefels and Langtang. The dynamic deformation features at these latter locations appear to be related to high strain rate tectonic processes associated with the landslide itself. We conclude that microscopic dynamic deformation features which occur in natural materials may have originated from meteorite impacts, from internal explosions, or from high strain rate tectonic process.