Abstract: Clay mineral studies of recent sediments from a diversity of environments in the vicinity of Rockport, Texas, have been made as part of American Petroleum Institute Project 51.
The bulk of the argillaceous material in these sediments is a complex mixture of poorly crystallized three-layer clay minerals. Problems of the identification and nomenclature of the components of such mixtures are considered.
Variations in areal distribution of the clay mineral constituents indicate progressive diagenesis in response to changing chemical environment. The gradual loss of montmorillonitic source material with the ultimate formation of poorly crystalline illitic and chloritic phases has been related to variations in environment. Environmental criteria based on clay mineral compositions are suggested.