Paleoecology of Early to Middle Miocene Deposits (Guri Member) and Sedimentary Environment, SE Zagros Zone, Roydar, Iran

Subject Areas : Mineralogy

Roya Fanati Rashidi ¹ , Seyed Hamid Vaziri ² , Keyvan Khaksar ³ , Hossein Gholamalian ⁴

1 - Department of Geology, Faculty of Basic Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 - Department of Geology, Faculty of Basic Sciences, North Tehran Branch, Islamic Azad University, Tehran, Iran
3 - Faculty of Basic Sciences, Qom Branch, Islamic Azad University, Qom, Iran
4 - Department of Geology, Faculty of Sciences, Hormozgan University, Bandar Abbas, Iran

Received: 2016-06-05 Accepted : 2016-06-05 Published : 2015-03-21

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Abstract :

This research focusses on the facies distribution, paleoenvironment and paleoecology of the foraminifera of the Guri Member in the northern Bandar Abbas Hinterland located in the Roydar area of southern Iran. The Guri Member is 570 meters thick and composed of limestone, argillaceous limestone and marl. The distribution of the foraminifera in the study area indicates the existence of three biozones ranging from early to middle Miocene in age. Based on petrographical studies, depositional textures and fauna, eight microfacies were identified. The paleoecology, lithology and environmental interpretations were characterized by an open marine environment with an upward, gradually shallowing trend. Additionally, three distinct depositional settings were identified: tidal flat, inner ramp and middle ramp. Microfacies (MF) 1, representing a distal middle ramp setting, was characterized by the occurrence of hyaline, benthic and planktonic foraminifera. MF2 and MF3 were characterized by the occurrence of Miogypsina, Elphidium and red algae. They represent a deeper low energy in the wave base of a middle ramp setting. MF4 was characterized by an abundance of rotaliids and red algae representing a proximal middle ramp environment. MF5 and MF6 were identified by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water inner ramp setting. MF7 and MF8 were characterized by the occurrence of gastropods and bivalves in a shallow-water setting of tidal flats influenced by both wave and tidal processes. Palaeolatitudinal reconstructions based on skeletal grains suggest that the Guri Member existed in tropical waters within a carbonate ramp.