The Upper Triassic Sphinctozoan Sponges of the Howz-e Khan Member of the Nayband Formation, Southwest of Naybandan, East Central Iran

The Upper Triassic sediments in the Central Iran are known as Nayband Formation. They are a set of carbonatic and detritic sediments that can be divided into several members. The carbonatic Bidestan and Howz-e Khan members contain a diverse fauna and flora. In order to study and identify the taxonomic inventory of the Howz-e Khan member, two profiles were studied in the Naybandan area. The first one is located in southwest of Dig-e Rostam and the second one in southwest of the type locality, which were both sampled systematically. Moreover, unsystematic samples were taken from different parts of the area, which led to the recognition of various algae, foraminifera and sponges. This paper introduces the following sphinctozoan sponges: Nevadathalamia variabilis, Amblysiphonella sp., Discosiphonella sp., Kashanella irregularis, Paradeningeria alpina, Tabasia maxima, Tabasia media, and Tabasia minima. The lithological and sedimentary structures as well as the microfacies indicate that the Howz-e Khan member has been formed in a shallow marine, near the coastal environment. These circumstances provided perfect conditions for patch-reef-forming organisms (here: sphinctozoan sponges) in the carbonates of the Howz-e Khan member.