Stratigraphic and palaeoenvironmental significance of Eocene palynomorphs from the Rusayl Shale Formation, Al Khawd, northern Oman

Abstract

Miospores recovered from the Rusayl Shale Formation of the Al Khawd section, northern Oman, are assigned an Early Eocene age, based on the co-occurrence of pantropical stratigraphic markers such as Proxapertites cursus, Spinizonocolpites echinatus, Rhombipollis geniculatus , and Intratriporopollenites microreticulatus . The sediments were deposited in a marginally marine environment under terrestrial influence, as indicated by the presence of very rare dinocysts and foraminiferal test linings, and significant amounts of cuticular material. The presence of Spinizonocolpites suggests a shoreline inhabited by mangroves. The occurrence of the mangrove taxon Avicennia , which today belongs to a coastal marsh vegetational community, supports the presence of tidal swamps near the area of deposition. The presence of the algal taxon Botryococcus is indicative of freshwater influence. The diversity of the angiosperm palynoflora, which forms the bulk of the assemblage,is thought to indicate a dense lowland vegetation cover.