Classification of Carbonate Rocks of Marine Origin

Abstract

Carbonate classifications in current use are to varying degrees subjective and interpretative. Objectivity in classification is highly desirable for an organization working with carbonates in widely separated localities because of the degree of uniformity in nomenclature and judgments concerning some of the properties of reservoir rocks that can be attained thereby. The classification presented here attempts objectivity and succeeds partly by using measured particle size as the basis for subdivision into major categories. Less objectively, it provides a method of distinguishing degrees and kinds of alteration of rock texture by the several processes of digenesis. A still greater degree of subjectivity is introduced unavoidably in the identification of the grains and cryst ls comprising the carbonate. Nevertheless, following the procedures prescribed leads even the inexpert to an accurate if not complete name for any carbonate, and any number of observers will arrive at essentially the same designation. Not a part of the classification, but included for completeness, is a discussion of the genetic implications of the texture and composition of carbonate rocks.