Delimitation of terrestrial impact craters by way of pseudotachylytic rock distribution

Details Delimitation of terrestrial impact craters by way of pseudotachylytic rock distribution Delimitation of terrestrial impact craters by way of pseudotachylytic rock distribution

Mar 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993lpi....24.1335s&link_type=abstract

In Lunar and Planetary Inst., Twenty-Fourth Lunar and Planetary Science Conference. Part 3: N-Z p 1335-1336 (SEE N94-20636 05-91

Mathematics

Logic

Bolides, Breccia, Geology, Meteorite Craters, Projectile Cratering, Tectonics, Canada, Deformation, Fragments, Meteorite Collisions, Minerals, Precambrian Period, Shock Waves, Vibration

Scientific paper

The determination of the shape and size of terrestrial impact craters is problematic, yet is critical to understanding cratering mechanics and for scaling bolide mass, volume, and impact velocity with crater size and target response. The problem is particularly difficult in older geological terrains (e.g. Precambrian) which are more likely to have suffered post-impact deformation and hence distortion of the original structure and/or where weathering may have partly removed or obscured its original shape. Traditionally, a number of features are used to assist us in determining the shape and size of an impact structure. These include the following: (1) the occurrence of faults, especially those disposed concentrically relative to the crater--the outermost ring faults being interpreted as indicating a viable minimum diameter; and (2) the development of so-called breccias, some of which are also associated with faults (e.g. the Sudbury Breccia developed within the target rocks of the Sudbury Structure of Onta rio, Canada). 'Breccia' is not a satisfactory term because a number of breccia-types exist at impact sites (e.g. fall-back breccias and in-situ brecciated target material). Of relevance to crater diameter determination is the recognition of discrete zones and fault- and shock-related pseudotachylyte. Pseudotachylyte is a rock type comprising a fine-grained, usually dark matrix containing clasts of minerals and/or rock derived from the country rock target material. It origin is normally attributed to high-speed slip (including vibration) along a slip surface (i.e. fault) or to the passage of a shock wave through the host material. The clasts can occur as angular fragments (i.e. like a breccia), but are more commonly developed as rounded to sub-rounded fragments. Significantly, the scale of these pseudotachylytes can range from sub-millimeter thick veinlets to dyke-like bodies up to 1 km or more thick. It is the latter, larger occurrence which has been referred to as 'breccia.' The smaller-sized occurrence is generally not recognized in the field, nor is it traditionally associated with its larger counterpart.

Affiliated with

Also associated with

No associations

Rating

Delimitation of terrestrial impact craters by way of pseudotachylytic rock distribution does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Delimitation of terrestrial impact craters by way of pseudotachylytic rock distribution, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Delimitation of terrestrial impact craters by way of pseudotachylytic rock distribution will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1450633