Palynostratigraphy و paleoecology سازند فراقون در جنوب غربی ایران
Abstract: The Faraghan Formation, a thick sequence of Upper Paleozoic strata of southern Iran, was studied palynologically to establish the palynofloras and determine more precisely the geological age of the Formation, and make logical interpretations of the depositional sites in order to reconstruct the palaeogeographic relationships of the Zagros Basin to northern and south hemispheres during the Upper Palaeozoic interval represented by these strata. 130 outcrop samples from the Faraghan area and 7 samples from the Chal-i-Sheh area were processed and the organic residues concentrated for microscopic analyses. The spores, pollen, acritarchs and some other organic entities were identified to genera and species and their relative abundances were calculated. 136 pollen, spores and acritarch species were described including 59 spores (36 genera), 51 pollen (33 genera) and 26 acritarchs (19 genera). These are arranged in five ascending stratigraphic assemblage zones. Zones I through IV represent part of Lower Devonian into middle Upper Devonian (probably Gedinnian to Frasnian). Zone V represents Lower Permian beginning during Sakmarian and ending in the Kungurian. The \"hiatus\" within the Faraghan Formation extends from Famennian through the Carboniferous period into Lower Permian. This \"hiatus\" possibly coincides with the hercynian orogeny that resulted in emergence of this part of the Zagros Basin producing extensive erosion of part of Late Devonian and the whole of the Carboniferous sediments or the combination of lack of deposition and erosion. Diverse acritarchs (25 species) in the Devonian of the Faraghan sections indicate a marine environment. However, the presence of 25 genera (48 species) of terrestrial spores suggests nearly terrestrial communities. Some of the Faraghan acritarchs are also recorded from Europe and North America, including Chomotriletes vedugensis. However, 10 species have been recorded only from Frasnian sediments of western Australia Patterns of Devonian palynomorphs are also similar to those recorded from the Arabian peninsula indicating a similar paleophytogeographic province, possibly proximal. Scolecodonts in the Lower Permain zone of the Faraghan sections, suggest marine influence. The terrestrial miospores of this interval include of 52 pollen species (33 genera) and 5 spores. These suggest; the existence of diverse, proximal conifer communities. This Lower Permain assemblage contains some species in common with those of North America, Europe and the Middle East. However, it contains many index species which have been recorded only from gondwanic continents, indicating that the Zagros Basin may have been part of Gondwana.