Palynology of strata associated with the Hercynian unconformity across the Arabian plate, from the Levant to southern Arabia

A survey of the palynostratigraphy of the strata above and below the Hercynian Unconformity (HU) indicates that the range of its associated hiatus, due to either non-deposition or erosion (or both), varies considerably across the Arabian Plate depending on the position of the succession in relation to the three main highs or arches, the Levant, Al Batin, and Oman-Hadhramaut arches, and any Hercynian faulting or other uplift in basinal regions, for example in the Ghawar region. As expected, the succession spanning the HU is most complete in basinal areas, for example in the Faydah-Jafurah and Nafud-Ma'aniya basins. The well with the shortest hiatus corresponding approximately to a maximum duration of part of the Serpukhovian and Bashkirian, appears to be KH-5/1, close to the axis of the Nafud-Ma'aniya Basin. Palynological assemblages in rocks above the HU indicate the diachronous onset of the basal Khuff clastics northwest through the Arabian Plate over a period of around 15 my. The oldest strata above the HU across the Arabian Plate also indicate systematic variation, probably due to palaeoclimate, with assemblages of similar age in Iraq and northern Saudi Arabia showing some similarities to those of Oman, but differences probably due to a strong climatic gradient at the time.