Shatter cone geometry and description procedure

Abstract

This procedure of systematic description of shatter cones defines a field station as a group of lithologically and structurally homogeneous outcrops, and requires the determination of the local tectonic setting within a cryptoexplosion structure and the evaluation of the relative abundance of shatter cones within each station. The orientation of the shatter cone axis and of the apical angle is derived from the measurement of the central striae on several non parallel shatter cone segments. The height of the master cone is determined from the attitude of the two marginal striae at either sides of each segment and the arc length between them. The other style elements of shatter cones require the description of the ornamentation and the evaluation of the length of the central striae. The proposed data sheet permits plotting the main observations, approximating the attitude of the cone axis and screening out erroneous measurements of various types in the field.