Abstract
Palynological investigations of Ora Formation and the upper part of Kaista Formation (Late Devonian – Early Carboniferous) in the Northern Thrust Zone were conducted in Kiasta exposures about 2km away to the north west of Kaista village Zakho District, Northern Iraq. The upper part of Kaista Formation is mainly composed of dolomitic limestone interbedded in the lower part with black shale, fine sandstone, and sometimes with lime mudstone, but in the upper part the facies is dominantly fossiliferous limestone. Ora Formation is composed of black shale and silty shales interbedded with siltstones and thin fossiliferous limestone. Based on available organic matter, ( phytoclasts, amorphous organic matters, and palynomorphs). Kaista section divided into five different palynofacies (PF1, PF2, PF3, PF4 and PF5). The detailed palynological study in Kaista section, having both Ora and Kaista Formations, enabled their division into five palynozones (P.Z1, P.Z2, P.Z3, P.Z4 and P.Z5). The basic index for this division is the miospores studied in the sum of 15 samples. The palynological analysis has confirmed the previously determined age of the studied formations, as (Late Devonian – Early Carboniferous) for the Kaista Formation and Early (Strunian- Late Tournaisian) for Ora Formation. The palynomorphs and the organic matters indicate that the depositional environment of Ora Formation is shallow marine to near shore. However, the depositional environment of the Kaista Formation was not established owing to scarcity of diagnostic palynomorphs.