An example of a kinking microfabric in Upper Pleistocene glaciolacustrine deposits from Llavorsi (Central Southern Pyrenees, Spain)

Abstract

Glacially deformed glaciolacustrine rhythmites exposed at Llavorsí in the Central Southern Pyrenees show a well-developed macroscopic crenulation lineation. Microscopic studies (thin sections and SEM) reveal a crenulation cleavage associated with very small-scale symmetrical folding and a banded extinction pattern. Combination of the thin section and SEM observations allows the reconstruction of a herringbone-like arrangement of finegrained particles or kinking microfabric. The occurrence of this microfabric can be used as a criterion for shearing, also in the absence of macroscopic observations.