Intrastratal rip-down clasts, Late Cretaceous Uhangri Formation, Southwest Korea

Abstract

Abstract Black shale clasts of various sizes and shapes occur in some tuffaceous mudstone, cherty mudstone, and fine standstone beds in the Uhangri Formation. The clasts include small, fibrous shale chips and large disc forms (0.5-65 cm long and 0.1 mm-8 cm thick). Existence of large, semidetached clasts in the upper part suggests that they were derived from the overlying bed rather than the underlying bed. These clasts, here termed rip-down clasts , were probably the result of liquefied intrastratal flow of tuffaceous and cherty muds and fine sand during penecontemporaneous deformation.