Lithofacies and thickness control by epigenetic dissolution—the dolomitic Timna Formation, Cambrian, southern Israel

Abstract

The Timna Formation (Cambrian) in southern Israel marks the first Phanerozoic transgression in the area. Its outcrops in the Timna Valley are intesively faulted, being adjacent to the Dead Sea rift valley. The upper part of the formation displays complicated lithofacies relationships, which include lateral changes from sandy dolomites into sandstones (manganese-rich) within very short distances. The distribution of the sandy lithofacies is not haphazard; it develops instead along linear features which were shown to be related to the joint and fault systems in the area. These lithological variations are accompanied by drastic thickness changes, the sandy lithofacies being thinner by a factor of 2–3 relative to the dolomitic lithofacies. The transitional areas between the two lithofacies are characterized by abundant deformational features, such as steeply inclined strata, rotated blocks and collapse structures. These observations led to the view that the sandy lithofacies was the result of differential dissolution. The close association between the sandy lithofacies and the fracturing pattern establishes an epigenetic origin for this dissolution. The structural analysis of the area suggests that the intensive fracturing and, hence, the discerned epigenetic dissolution, are of Neogene age.