- GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Anhydrite, a common evaporite in all systems since the Cambrian, displays a variety of structures which may be classified as layered, mosaic, flocculent, contorted, boudinage, and authiclastic. A primary origin of these structures and of the anhydrite itself is suggested by interbedding of undeformed anhydrite and clastics with layers of disturbed anhydrite. Flowage resulting from differences in density of semifluid anhydrite and unconsolidated nonevaporite sediments during or shortly after deposition seems to explain the origin of the structures observed. Model experiments in which most of the structures were simulated by artificial sedimentation techniques support this conclusion.