6533b827fe1ef96bd1286d80

RESEARCH PRODUCT

Interpretation of Structures and Fabrics Recognition and Interpretation of Fabric Patterns in Outcrop

subject

description

High-grade gneisses with a long and complex history have a finite ‘memory’ of past events. This memory is formed by fabric elements such as foliations, lineations, folds, mineral assemblages, boudins and sequences of intrusion. One of the aims of a geologist is to tap this memory as effectively as possible. The memory of rocks, however, is rather inadequate in that it is partly destroyed by the same events which produce the fabric elements that are recorded (Williams, 1983). Strong deformation erases older fabric elements; intrusions, recrystallisation and partial melting do the same (Figs. 1.1; 4.1). One of the purposes of this manual is to help geologists working in high-grade gneiss terrains to recognise the effects which modify or obliterate the rock’s memory, and to obtain all the data from the rock which are still available.