Computerized Modeling of Rock-Varnish Dating

Abstract

One type of epigenetic alteration of recent sedimentary formations is desert weathering. Rock varnish is a widespread feature of a stony desert landscape throughout the world. It is a product of complicated physical and chemical processes under arid and semiarid environments. Despite the interest in rock varnish of both archeologists and geologists, the mechanism of varnish formation is controversial. Most workers believe that the formation of rock varnish is responsible for changing pH and Eh conditions on its surface layer, which results in solution and subsequent deposition of matter (Tricart et al. 1960). These researchers consider this process as insolative weathering of deserts which consists of circulation in mineralised solutions to a rock surface, evaporation and mineral deposition. Some investigators advance arguments which indicate a biogenic nature of manganese layers (Krumbein et al. 1981). In addition, it is also believed opinion that patina has a primary eolian origin (Allen 1978; Dorn et al. 1981).