Authigenic clays and stylolites in the carbonate reservoirs of the Permian Basin

Authigenic clay minerals are found in back-reef carbonate rocks ofthe Upper Permian Artesia Group ofthe northwestern shelf of the Delaware Basin. The authigenic clays are located in the vugs and pore spaces of the carbonates. Stylolites from these rocks do not show clays of authigenic origin, however detrital clays and other minerals such as illite, quartz, feldspar, and pyrite are accumulated in the stylolite seams in these carbonates.

Authigenic clays in pores and vugs of carbonate samples were studied using x-ray diffraction, and electron imaging such as SEM, TEM, and STEM. Dickite is the predominant authigenic clay mineral. It occurs mostly in euhedral hexagonal platelets. Authigenic illite is rarely observed, and it occurs as laths and fibers.