LITHOSTRATIGRAPHY AND LARGER FORAMINIFERAL (NUMMULITID) BIOSTRATIGRAPHY OF THE TERTIARY OF NORTHERN OMAN

A thick sequence of predominantly shallow marine carbonates of Late Paleocene to Early Miocene age crop out discontinuously over some 2,500km(2) in the foothills of northern Oman yield substantial new biostratigraphic and palaeoenvironmental data. The lithostratigraphic sequence is redescribed and four new units are distinguished: the Rusayl Conglomerate Beds, Silvestriella Beds, Ma'ahm Beds and Ma'ayh Beds. Larger foraminifera are particularly abundant and diverse throughout these dominantly carbonate sequences, and allow these formations to be dated accurately for the first time using zonal schemes introduced by Schaub (1981) for Nummulites and Assilina in the Mediterranean region. Sixty-nine species/subspecies are described and illustrated: thirty-nine of Nummulites, six of Operculina, thirteen of Operculina (Assilina), two of Ranikothalia, five of Heterostegina, two of Spiroclypeus and two of Cycloclypeus. Of these, fifty-one are new to Oman, twenty-eight are new to the Middle East and three are new species. The Oman fauna contains Mediterranean, Indo-Pakistan, cosmopolitan, and endemic elements. Seventeen of the forty seven species of Nummulites and Assilina used to define biozones in the Mediterranean region are identifiable in Oman. These allow eleven of the eighteen successive time intervals recognized by Schaub as spanning the Middle Ilerdian (early Ypresian) to Early Oligocene to be recognized in the Oman Tertiary sequence.