Age and paleoenvironment of the Sirenia-bearing deposits in the Zagros Basin, south-southwest Iran

The chronological and paleoenvironmental settings of the Sirenia-bearing strata in the Zagros Basin of Iran were studied in four sections. These sections, located in the Izeh (Asmari Formation), Interior Fars (Gachsaran Formation), and Coastal Fars (Mishan Formation) zones of the Zagros Basin, were investigated for the details of their micropaleontology, biostratigraphy, and microfacies. A total of 113 thin sections were analyzed. Fossils from the Asmari Formation and the Gachsaran Formation were younger (Burdigalian), while those from the Mishan Formation were older (Aquitanian). Thirteen carbonate microfacies were identified in three facies belts; tidal flat, inner ramp, and middle ramp. The tidal flat facies association included mudstone microfacies. Inner ramp facies association consisted of bioclast with porcelaneous tests wackestone, peloid and miliolids packstone to grainstone, bioclast and miliolids wackestone to packstone, benthic foraminifera grainstone, red algae with bryozoan and miliolids wackestone to grainstone, and echinoid and miliolid packstone to grainstone facies. Middle ramp facies association was comprised of red algae and meandrous coral packstone to rudstone, coral floastone, bioclast and bryozoan wackestone to packstone, echinoid and bryozoan packstone, bryozoan and benthic foraminifera wackestone to packstone, and echinoid and bioclast wackestone facies. A shallow carbonate ramp was identified as the habitats of sea cows in the Aquitanian-Burdigalian of the Zagros Basin.