Identification of Reworked (Contaminated) Early Cretaceous Dinoflagellate Cysts in the Butmah Formation (Early Jurassic) in Borehole Tel-Hajar-1.

During the Palynological study of well documented Lower Jurassic Butmah Formation, Lower Cretaceous reworked Dinocysts are identified (11 genera and 12) species as follows:Spiniferites ramosus; Endoscrinium luridum; Operculodinella operculata; Hystrichodinium pulchrum; Palaeo Peridinium cretaceum; Pareodinia ceratophora; Endoceratium turneri; Endoscrinium pharo; Coronifera oceanica; Achomosphaera neptuni; Glossodinium dimorphum. The identification of these reworked Dinocysts genera and species are typical of Lower Cretaceous age. These results confirm and support that these Dinocysts were probably originated and infiltrated from the younger Garagu Formation (Lower Cretaceous) (Late Berriasian-Vallangenian) age that rests unconformably upon the Sargelu Formation of Mid Jurassic (Bajocian-Bathonian) age and supporting the presence of unconformable (a break) relationship between uppermost Jurassic (Tithonian) and lowermost Cretaceous (Early Berriasian) successions in this subsurface section, which is marked by the missing of Gotnia Formation (Late Jurassic) (early Tithonian-Callovian) age and the Lower Sarmord due to an active erosive or non-depositional processes occurred in the studied section. These associations of Lower Cretaceous Dinocysts are of great taxonomic and biostratigraphic value for further future studies on the Lower Cretaceous successions in Iraq. These species are important in palaeontology because they can be used to identify and dating the age of rock formations as well as providing information about the mode of type of life that existed during a particular time period. Dinocysts can also be used to reconstruct ancient environments and climates making them a valuable tool for understanding the history of the Earth.