RECOGNIZING NON-STEADY-STATE WEATHERING CONDITIONS IN ANCIENT SUBMARINE FAN SYSTEMS: CORRECTING FOR K-METASOMATISM REVEALS A LATE CRETACEOUS NON-STEADY-STATE WEATHERING REGIME, POINT LOMA FORMATION, SOUTHWESTERN CALIFORNIA, USA

摘要

During steady-state weathering, the rate of removal of the exposed weathering zone is balanced by the rate of generation of mineralogically identical material through chemical weathering. As steady-state conditions prevail, the mineralogical and chemical composition of sediments derived from the weathering profile should be invariant over time. In A-CN-K space, a steady-state weathering condition is characterized by tightly grouped compositions, with dispersion between sands and muds a consequence of sorting during fluvial transportation. The purpose of this study was to assess whether such a condition was present during the development of the Upper Cretaceous Point Loma Formation.