Paleobathymetry of the Purple shales of the base of Pabdeh Formation at Darreh-Shahr and type sections using palynofacies analyses

Document Type : مقالات پژوهشی

Authors

Javad Rabbani

Ebrahim Ghaseminejad ¹

Ali Reza Ashouri ²

¹ تهران

² دانشگاه فردوسی مشهد

10.22067/sed.facies.v6i2.14474

Abstract

The basal unit of the Pabdeh Formation at Darreh-Shahr section is composed of 153m and in type section 102m consists of shale and marl of purple to green and gray in color. These beds gradually change to shale and argillaceous limestone at the top of the sections. In order to study palaeobathymetry and palaeoecology of these beds, we used palynological (palynofacies) evidences. Three Palynofacies types (VI: Proximal suboxic – anoxic shelf , VIII: Distal dysoxic-anoxic shelf, IX: Distal suboxic-anoxic basin) in Darreh-Shahr and three Palynofacies types (VI: Proximal suboxic – anoxic shelf , II: Marginal dysoxic – anoxic basin, IX: Distal suboxic-anoxic basin) in type section of the Pabdeh Formation have been determined that propose a proximal - distal shelf and distal basin for Darreh-Shahr and proximal shelf and marginal to distal basin for type section as depositional setting. Correlation of palynofacies evidences between these two sections, high abundance of phytoclasts and very low abundance of marine palynomorphs in type section show that purple shale in type section have been deposited in a shallower and more oxygenated environment with more oxidation in type section in comparison with the Darreh-Shahr section.

Keywords

palynofacies

palaeobathymetry

purple shales

Pabdeh Formation

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