Larger Foraminifera From the Upper Oligocene of the Venetian Area, North‐east Italy

Abstract

A moderately diverse larger foraminiferal fauna from the north-east Italian 'Arenarie e calcari di S. Urbano' formation with important stratigraphic, palaeoecological and palaeobiogeographical implications is described with respect to its position in the Western Tethys area. The fauna is dominated by hyaline perforated and porcellaneous forms including Amphistegina, Archaias, Austrotrillina, Miogypsinoides, Neoplanorbulinella, Neorotalia, Nummulites, Operculina and Spiroclypeus. The presence of Miogypsinoides complanatus allows the age of the formation to be determined as late Chattian (Shallow Benthic Zone SBZ 23). The palaeoenvironmental setting is interpreted as a shallow ramp environment ranging from (1) well lit, highly translucent, shallowest part of the photic zone characterized by Archaias and Austrotrillina, the deeper part of the inner ramp with Nummulites, to (2) the shallow part of the middle ramp with Spiroclypeus and miogypsinids and Operculina, to (3) a deeper middleramp setting dominated by coralline rhodoliths along with lepidocylinids. The presence of Archaias hensoni Smout and Eames shows that members of much more diverse Middle Eastern associations of shallow-water larger porcellaneous foraminifera are also present in the north-western parts of the Western Tethys, and reveals a corresponding diversity gradient among larger foraminiferal faunas in the Western Tethys, which is related to a decrease in temperature.

Facies analysis and sequence stratigraphy of the Asmari Formation in the northern area of Dezful Embayment, south-west Iran

“…The depositional textures, the fauna and the lack of general features representative of emergent conditions, support the interpretation of facies 8 and 9 as being deposited in warm euphotic, shallow water, within an inner shelf setting. This interpretation is supported by the presence of abundant and diverse imperforate foraminifera (Geel, 2000;Corda and Brandano, 2003;Vaziri-Moghaddam et al, 2006;Bassi et al, 2007). Facies 10 was deposited in a marinerestricted environment.…”

“…High taxonomic diversity of perforate foraminifers, corallinaceans, echinoids, bryozoans, mud micrite matrix as well as the stratigraphic position suggests the deposition of facies 2 in a shallower slope environment (Amirshahkarami et al, 2007). The abundance of deep living larger foraminifera (large and flat nummulitids and lepidocyclinids) and the presence of typical open marine skeletal fauna including echinoids and corallinaceans suggest sedimentation in the middle shelf's oligophotic zone (Geel, 2000;Bassi et al, 2007;Brandano et al, 2009). The red algae association and larger benthic foraminifera (facies 3) were identified as living in the oligophotic zone of the middle ramp environment (Pomar, 2001;Brandano and Corda, 2002;Corda and Brandano, 2003).…”

Planktonic and benthic foraminiferal biostratigraphy of the Middle Eocene–Lower Miocene successions from the Sivas Basin (Central Anatolia, Turkey)

“…shallow shelf lagoon ;Wilson 1975;Epting 1980;Flügel 1982). Almost similar foraminiferal facies were reported from the shelf lagoon or inner ramp environments in Iran (Vaziri-Moghaddam et al 2006;Amirshahkarami et al 2007;Rahmani et al 2009;Seyrafian et al 2011 andSajadi et al 2014), from NE Italy (Bassi et al 2007), from SE Turkey (Sirel 1996(Sirel , 2003 and from back reef environments in Iraq (Edgell 1997;Al-Banna 2004). In contrast to the Tuzlagözü section, the limestones enclosing the foraminiferal packstone-grainstone facies alternate with pelecypod bearing sandstone, fossiliferous (mainly ostracoda) siltstone with plant fragments, sandy conglomerate and evaporites and mudstones with planktonic foraminifera in the Egribucak section (Fig.…”

Sedimentary Environment and Relative Sea Level Changes of the Asmari Formation Deposited in Lurestan Basin, Southwest of Zagros

“…Red algae and large foraminifera indicate the deposition of this microfacies in oligophitic realm [47] [48]. Sediments enriched with nummulite and lepidocyclina are lenticular and round.…”