Clay minerals and feldspars in argillaceous strata of the Judea Group in the Jerusalem Hills

The noncarbonate minerals of the argillaceous layers of the Cretaceous Judea Group comprise clay minerals as well as quartz and K-feldspar and, occasionally, pyrite. In most of the argillaceous layers illite is the dominant clay mineral, followed by smectite and randomly interstratified illite-smectite, whereas regularly interstratified illite-smectite is rare. Kaolinite is a major component only in the Moza Formation. Palygorskite and K-feldspar are the only authigenic minerals. K-feldspar is present in most of the samples, whereas palygorskite occurs sporadically and is confined to the Soreq Formation. The presence of palygorskite in the Soreq Formation indicates distinctive conditions, probably local lagoons, in agreement with the geological evidence. The distribution of kaolinite may serve as a paleoenvironmental indicator. -from Authors