نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه آزاد اسلامی، واحد تهران شمال
2 دانشکده علوم زمین، دانشگاه خوارزمی
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The Geirud Formation at the Kalariz Section, northeast Damqan, comprises of 220 m of alternating basal conglomerate, quartzite, reddish sandstones followed by fossiliferous dark limestone with thin intercalations of shales. It disconformably overlies the Mila Formation and gradually succeeds the Mobarak Formation. Diverse, relatively well preserved palynofloras consisting of 26 species assigned to 13 genera of microphytoplanktons (4 genera and 9 species of Prasinophyte phycomata and 9 genera and 17 species of acritarchs), spores (21 species attributed to14 genera of exclusively trilette spores) and scoleocodonts occur in the material studied. Additionally cryptospores, albeit with far less abundance, are also recorded. Presence of such index fossil forms as: Cymatiosphaera perimembrana, Papulogabata annulata, Tornacia sarjeantii, Unellium lunatum, Unellium piriforme, Deltotosma intonsum, Geminospora lemurata, Densosporites spitsbergensis, Cymbosporites catillus and Punctatisporites planus allows attribution of Late Devonian age (Frasnian - early Famennian) to the pertinent material. Notable absence in the palynofloras studied of Retispora lepidophyta militates against any indication of late Famennian strata being present. Spores recorded from different rock samples are generally similar, denoting an almost uniform complexion unorthodoxically named assemblage zone I herein. Co-occurrence of spores and marine Palynomorphs indicates a marginal marine depositional setting. Spores- parent plants relationships alludes to presence of such diverse components as Progymnospermopsida, Cycadopsida, Zosterophyllopsida, Rhyniopsida, Filicopsida, Lycopsida, Barinopsida, Equisetopsida, close to the depositional site. Presence of Densosporites , Punctatisporites, Geminospora and Cymbosporites coeval testifies to domination of Lycopsida and Filicopsida in the coeval vegetation. Comparison between the palynofloras studied with those coeval host rocks from Iran indicates notable similarity with assemblages from the Alborz and Central Iran, and elswhere with those of the Western Australia. It could be said that Iran and Australia were probably located at comparable latitudes and also that migration routes might had been available between the Alborz and Central Iran at this time.
کلیدواژهها [English]
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