Microfacies and paleoenvironmental interpretation of the Upper Jurassic Esfandiar Formation (East-central Iran)

Abstract

Microfacies and paleoenvironmental investigation was carried out on the Upper Jurassic Esfandiar Limestone Formation exposed at kuh-e-Esfandiar, south of Shotori Mountains, east-central Iran. Interpretations of microfacies analysis, investigation of benthic foraminifera, sponges, and their paleoecology were performed. The Esfandiar Formation is composed of grey thick bedded to massive limestone with included major biota: sponges (Cladocropsis mirabilis, Neuropora sp., Chaetetes sp.) corals, bivalves, gastropods, and benthic foraminifera. Based on the study of rock samples in the field and of thin-sections in the laboratory, nine main facies types have been recognized. These facies are characterized by a sheltered interior platform setting for the Esfandiar Formation. Also some benthic foraminifera with considerable stratigraphic value within the Mesozoic Tethys are recognized. Our study presents preliminary biostratigraphic results of foraminifera from the Esfandiar Formation and provides a direct age determination (Middle Oxfordian-Lower Kimmerdgian) for the Esfandiar Formation.