Island Arc Sedimentation in the Middle Devonian Kennett Formation, Eastern Klamath Mountains, California

Abstract

The Kennett Formation is a unit of intra-arc sediments which was deposited during the final stages of Early to Middle Devonian island arc construction in the Eastern Klamath Mountains, California. Nearshore bioturbated volcaniclastics with a shallow marine fauna also contain rare debris of land plants, indicating island source areas. These sediments grade to volcaniclastic turbidites of slope origin which in turn grade to thin-bedded siliceous mudstone representing a basin floor environment. Limestone lenses at the top of the Kennett are debris deposits with matrix-supported intraclasts and overturned colonial skeletons which were derived from shallow carbonate banks. Sedimentary facies of the Kennett indicate a mature arc topography of islands, submerged highs and intra-arc basins. Basins were probably developed by tectonic extension of the arc during the Early Devonian.