Major Subdivisions and Depositional Environments of Nubia Strata, Southwestern Egypt

Nubia strata in southwestern Egypt are more than 1,000 m thick and range in age from Jurassic to Late Cretaceous. Throughout much of the area, the interval can be subdivided into six distinct and traceable units. Three medium to coarse-grained sandstone units 100 to 500 m thick are interpreted as alluvial-plain deposits composed of cross-stratified shallow channel and massive rooted flood-plain cycles. Overlying each of these sandstone units is a siltstone or shale unit which is of marine, marginal-marine, or coastal-plain origin. These marine-influenced units suggest transgressions of latest Jurassic, middle Cretaceous, and latest Cretaceous ages, possibly correlative with worldwide eustatic sea-level rises. Because of extensive floral remains, the climate is thought to have been warm and humid to semihumid. There is no evidence of aridity during the Jurassic or Cretaceous in this area. Southwestern Egypt contains the most extensive Nubia exposures in Egypt and is very favorable for dating, subdivision, and interpretation of these strata.