DIAGENETIC FABRICS IN THE AVONIAN LIMESTONES OF DERBYSHIRE AND NORTH WALES

Abstract

Summary Detailed fabric studies of the Avonian limestones of Derbyshire and North Wales have revealed complex diagenetic histories, and have shown that fibrous calcite commonly results from the late modification of an originally fine mosaic. The development of this fabric also produces certain types of pseudobreccias. Grain diminution, resulting from the recrystallization of crinoid ossicles and cementation fabrics, has also been observed in these rocks. The limestones exhibit a variety of cavities which owe their present fabrics to a complex of processes, and in some cases to modification by diagenetic fibrous calcite development. The complexity of diagenetic histories, the caution necessary in their interpretation, and the effects of diagenesis on field classifications are emphasized by these studies.