Palynostratigraphy and Reconsideration of the Shemshak Group Based on Dinoflagellate Cysts

Ghasemi-Nejad, E.; Asadi, M.,; Shahmoradi, M.; Aghanabati, A.; Mohtat, T.

doi:10.22071/gsj.2012.54071

Document Type : Original Research Paper

Authors

¹ Professor, School of Geology, University College of Science, University of Tehran, Tehran,

² M. Sc., Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran

³ 2 M. Sc., Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran.

⁴ Associate Professor, Research Institute for Earth Sciences, Geological Survey of Iran, Tehran, Iran.

⁵ Ph.D., Paleontology Group, Geological Survey of Iran, Tehran, Iran.

https://doi.org/10.22071/gsj.2012.54071

Abstract

The Nayband Formation was sampled at Chal-Sefid and Zard mountains in central Iran, for palynology and palynostratigraphy in order to take the advantage of dinoflagellate cysts to locate the Triassic and so called Jurassic boundary. The Chal-Sefid section is located about 45 km southwest of Kashan city and Zard Mountain some 70 km northeast of Esfahan. The studied strata attain a thickness of 1750 meters in Chal-Sefid and 1820 meters in Zard Mountain. They consists sandstone and shale beds. Totally 75 samples from Chal-Sefid and 22 samples from Zard Mountain were collected and treated in the Palynology laboratory of the Geological Survey of Iran. The recorded dinoflagellate cyst species were differentiated in four palynozones in Chal-Sefid and two palynozones in Zard Mountain as follows: Chal-Sefid section: Palynozone 1: Rhaetogonyaulax wigginsii, encompasses 160 meters of the section, suggesting an early to middle Norian age. Palynozone 2: Suessia listeri with a thickness of 140 meters, suggesting a middle Norian age. Palynozone 3: Hebecysta balmei encompasses 550 meters of the section, suggesting middle to late Norian age. Palynozone 4: Rhaetogonyaulax rhaetica with a thickneses of 900 meters suggests an early to middle Rhaetian age. Zard Mountain section: Palynozone 1: Hebecysta balmei, encompasses 442 meters of the section, suggesting a middle to late Norian age. Palynozone 2: Raetogonyaulax rhaetica, encompasses 491 meters of the section, suggesting an early to middle Rhaetian age. It is revealed that all the rock units investigated here are of late Triassic age and no evidence of Jurassic ages was identified.

Keywords

20.1001.1.10237429.1391.22.86.13.3

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Scientific Quarterly Journal of Geosciences

Palynostratigraphy and Reconsideration of the Shemshak Group Based on Dinoflagellate Cysts

References

References

Volume 22, Issue 86
December 2012
Pages 99-106

Palynostratigraphy and Reconsideration of the Shemshak Group Based on Dinoflagellate Cysts

References

References

Volume 22, Issue 86December 2012Pages 99-106

Volume 22, Issue 86
December 2012
Pages 99-106