Paleo-weathering zone of Cretaceous red mudstone underlying Quaternary loess deposit: a case study on a typical profile

Abstract

Present study consists the engineering geological properties and weathered texture of a typical paleo-weathered crust of Cretaceous red mudstone in Lanzhou, Gansu province, China, focusing on the unconformity on its superface. Field hardness and magnetic susceptibility tests in addition to scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were conducted to examine the weathering degree of the zoning of the crust profile. The degree of the paleo-weathered red mudstone can be relatively classified into four distinct zones. The paleo-weathered crust has distinct degrees of vertical zones, with the rock becoming more fragile as weathering degree increases, and the slaking is positively related to the weathering degree.