Writers : Hadad Tavakoli,Elham ;supervisor:F.Sajaddi
Refference : M.Sc.Thesis _ Tehran university,Tehran
Publishing Year : 1384

Abstract :

The palynology of the Kashafrud Formation in three surface sections (Ghale Sangi, Tappeh Nader and Gas Pipe Line) has been studied. The Ghale Sangi Section which is situated in the east of Mashhad, 15 km east of Bagbago Village, contains of conglomerate, sandstone and shale with a thickness of about 1090 meters. In this section, the Kashafrud Formation overlies with a coarse basal conglomerate and a strong angular unconformity Sina Formation and it is disconformably overlain by the limestone of Mozduran Formation.
Tappeh-Nader Section which is situated 20 km northwest of Senjedac Village, north of Shahan mountain, contains conglomerate, sandstone and shale with a thickness of about 200 meters. In this section the Kashafrud Formation unconformably overlies ophiolites rocks.
Gas Pipe Line Section is situated 25 km of Mashhad-Sarakhs road, northeast of Mayamei, between Kashafrud River and Bazangan mountain, contains of sandstone and shale with a thickness of about 453 meters. In this section the Kashafrud formation overlain transitionally by chamanbid Formation and its base is faulted.
Collectively 165 samples of black shale selected and 545 palynological slids were prepared. Moderately diverse and reasonably well-preserved palynoflora only occurred in the middle to upper parts of the Ghale-Sangi Section.
In this study 60 species of spore (distributed among 36 genera), 22 species of pollen (distributed among 12 genera), 19 species of dinoflagellates (distributed among 14 genera), 1 species of acritarch (distributed among 1 genera), 2 species of alge spores (distributed among 2 genera) and 3 species of fungal spore (distributed among 3 genera) have been identified. Of these, the miospores are mainly radiosymmetrical and triletes, wheras the pollen are represented by monosulcate, monosaccate, bisaccate and three saccate taxa.
Dinoflagellates, fungal spores, algae spores, acritarchs and foraminiferal test lining occure in minor proportion. Of the palynoflora assemblage Klukisporites, Dictyophyllidites and Cyathidites are particularly abundant.
The abundance of klukisporites, Dictyophyllidites and comparision with the assemblage zones which identified in Australia by Filatoff (1975) with the name Dictyophyllidites Assemblage Subzone and in Afghanistan by Ashraf (1977) with the name Ischyosporites variegates-Duplexisporites problematicus zone a Middle Jurassic age was proposed for Ghale-Sangi Section.
Moreover disappearance of Striatella seebergensis and appearance of Confignisporites burgeri suggest a Bajocian-Bathonian age for this interval. In the study section, the two interval zone consisting of Striatella seebergensis and Contignisporites burgeri which previously established from Senjedac section of Kashafrud (in southeast of Mashhad) have been recognize. A detailed comparision of the Ghale-sangi palynoflora (east of Mashhad) with the Senjedac (southeast of Mashhad) suite indicate that the two assemblages feature significant quantitative and qualitative palaeofloristic similarities and suggest a similar depositional and climate conditions in the east and southeast of Mashhad during the Bajocian-Bathonian. The coefficient of similarity for Senjedac and Ghale-Sangi Section was calculated as 30/30. So, it can be concluded that Two mentioned sections were part of the same. Palaeogeographic province possessing good marine connection during the Bajocian-Bathonian. On the other hand abundance percentage of palynoflora (spore & pollen) to marine palynomorphs (proximate dinoflagellate) collectively implies an open marine, near shore depositional setting for Ghale-sangi Formation. Inferred natural relationship spores and pollen grains imply derivation from a diverse parental flora (e. g. Pterophyta, Brayophyta, Cycadophyta, Ginkgophyta, Coniferophyta, and Lycopodophyta). The presence of some dinoflagellates companied by fungal spores testified warm temperature conditions during Bajocian-Bathonian.
The percentage of palynological group such as marine palynomorphs, Amorph Organic Matter (AOM) and palynomaceral signifies an open marine, near shore depositional setting with high content of oxygen for the study section. Comparing the yellowish orange colour of the palynomorphs indicate that the palynofloras tolerated some chemical changes, marginally mature but not likely to have potential as a commercial source of petroleum and darkbrown-black color of palynomorphs content in Tapeh-nader and Gas pipe line indicate over mature step and source potential for dry gas.
Comparision of the Kashafrud Formation with the Shemshak Formation indicates that in eastern Kopeh Dagh Basin upper part of the Shemshak Group latteraly changes to the Kashafrud Formation with more marine influence. Co-occurrence of miospores, pollen and proximate dinocysts implies a nearshore marine setting for the Kashafrud Formation. This is in contrast to deltaic environment with intermittent marine incursions supposed for the Shemshak Formation. Thus, the two rock units differ in terms of age, depositional environment and facies.

Subject List : Palinostratigraphy