Stratigraphic note: Update of the standard Arabian Permian palynological biozonation; definition and description of OSPZ5 and 6

Abstract

A standard Early and Middle Permian palynological biozonation was erected for Arabia in 2003 (Stephenson et al., 2003), following extensive palynological work in sequences in Oman and Saudi Arabia. Oman-Saudi Arabia Palynozone 4 (OSPZ4), and the succeeding two biozones OSPZ5 and 6, were established in the sporadically palyniferous Lower and Middle Permian sequences of Oman and Saudi Arabia. In 2003, the exact stratigraphic relationships between OSPZ4, 5 and 6 were not clear because in no section were the biozones seen to be in contact with one another. To express this uncertainty, the bases of OSPZ5 and 6 were represented by dashed lines in figure 2 of Stephenson et al. (2003). New work on the upper and middle Gharif members in Barik-36, Oman indicates: (1) the transition from OSPZ4 to 5 assemblages; (2) the transition from OSPZ5 to 6 assemblages; and (3) clearly that OSPZ6 is stratigraphically above OSPZ5 in Oman. The stratigraphic distribution of key taxa in Barik-36 allows the following definitions: the base of OSPZ5 is defined as the horizon of the combined first uphole appearance of Distriatites sp. A, Distriatites insolitus, Indotriradites sp. C, Playfordiaspora cancellosa and Thymospora opaqua, and the base of OSPZ6 is defined as the horizon of the first uphole appearance of ? Florinites balmei. Ages for the OSPZ5 and 6 biozones remain substantially the same as indicated originally in Stephenson et al. (2003), though it is probable that the lower part of OSPZ6 is of Wordian age, extending into the Capitanian.