Palynostratigraphy of the Middle Jurassic sediments in Hojedk Formation, Tabas Block, East-Central Iran

摘要

Diverse and moderately preserved palynofloras occur in the Middle Jurassic sediments of the Hojedk Formation in the South Kouchekali, southwestern of Tabas, east central Iran. The palynofloras comprise thirty-nine species including spores (fourteen species allocated to nine genera) and various types of pollen (twenty-five species designated to thirteen genera). Vertical distribution of miospores allows erection within the Hojedk Formation of one biozone-Klukisporites variegatus Assemblage zone-and two distinctive stratigraphically successive biozones, viz. Callialasporites trilobatus-Parcisporites cacheutensis Assemblage zone, and Contignisporites problematicus Taxon range zone based on the first observed occurrence (FOO) and the last observed occurrence (LOO) of selected taxa. These biozones are compared with palynozones from ±coeval strata in Iran and elsewhere. Based on the association of key miospore species such as Klukisporites variegatus, and Callialasporites dampieri within the Hojedk palynofloras, the host strata are assigned to the Middle Jurassic. Abundance of ferns and cycadophytes in parent floras implies that the host strata accumulated under a moist warm climate during the Middle Jurassic in this locality.