Facies development during late Early–Middle Cambrian (Tayan Member, Burj Formation) transgression in the Dead Sea Rift valley, Jordan

Abstract

The transgressive Tayan Member of the upper Lower to Middle Cambrian Burj Formation (Jordan) has been investigated in several localities of the Dead Sea Rift valley, Jordan. The lower portion of this member consists of low-energy siliciclastics with indications of temporary, early pedogenetic processes, pointing to some stagnation during transgression. The upper portion of the member was deposited under higher energy conditions. Stromatolites, desiccation cracks, halite- pseudomorphs, laminated dolostones, and tepees, together with ripples, mud-clasts and scours point to a shallow intertidal to supratidal sabkha-related environment in a climate of tropical to subtropical aridity. The fossil content of the Tayan Member consists exclusively of trace fossils. Simple endobentic, worm- like r-strategists are common in some horizons. For the first time, Treptichnus pedum has been repor- ted from Jordan where it was found near the base of this member. The markedly reduced biodiversity together with sedimentological data led to the interpretation of a strongly stressed, paleoecologically unstable habitat. Regional comparisons with high-energy transgressive environments laid down at the same time show that the main factors controlling facies development and the migration of facies belts are (1) the topography of the flooded surface and of the hinterland (mainly with only a local effect), (2) the configuration of the coast (local effect), (3) the rate of subsidence and transgression (local to regional effects), and (4) climate (large regional effects). The combination and overlap of these factors controlled facies gradients and may explain special differences between the facies of the Jordanian and those of the near-by Israeli transgressive deposits on the one hand, but, also the obvious general similarity of Lower to Middle Cambrian transgressive successions in the Middle East and the Mediterranean part of Gondwana on the other hand.