Palynostratigraphy of the Nayband Formation, Tabas, Central Iran Basin: Paleogeographical and paleoecological implications

Sponges, along with scleractinian corals, are among the main reef-building organisms in Triassic reefs. Hypercalcified groups, including the chambered sphinctozoans, and the unchambered inozoans, chaetetids, and spongiomorphids, represent the most abundant Triassic reef-building sponges. Earlier workers have described elements of the latter group as “hydrozoans.” Hexactinellid sponges, abundant in some Permian reefs (e.g., in Texas, Finks, 1960), are rarely known from similar Triassic deposits, in general (Tichy, 1975), and particularly from Upper Triassic stratigraphic units. Hexactinellid sponges have been sporadically reported from well-investigated Upper Triassic reefs in the western Tethyan region (e.g., Keupp et al., 1989). However, a variety of hexactinellid sponges have been reported from Upper Triassic deposits and reefal limestones of the northern and central Tethyan realm (Boiko, 1990; Wu, 1989; Wu and Xiao, 1989; Rigby et al., 1998).

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Differentiation of delta and open marine deposits based on an integrated ichnological and sedimentological analysis of the Late Triassic Nayband Formation, Tabas Block, Central Iran

Journal of Iberian Geology ◽

10.1007/s41513-017-0031-5 ◽

2017 ◽

Vol 43 (3) ◽

pp. 413-437 ◽

Cited By ~ 7

Author(s):

Aram Bayet-Goll ◽

Carlos Neto De Carvalho

Keyword(s):

Central Iran ◽

Late Triassic ◽

Marine Deposits ◽

Nayband Formation

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Wildfire Events at the Triassic-Jurassic Boundary of the Tabas Basin, Central Iran

10.21203/rs.3.rs-97849/v1 ◽

2020 ◽

Author(s):

Majid M Alipour ◽

Bahram Alizadeh ◽

AmirAbbas Jahangard ◽

AhmadReza GandomiSani

Keyword(s):

Major Change ◽

Lower Jurassic ◽

Upper Triassic ◽

Central Iran ◽

Sharp Boundary ◽

Depositional Settings ◽

Run Off ◽

Clastic Sediments ◽

Nayband Formation ◽

Microscopic Charcoal

Abstract This paper presents organic geochemical evidence pointing to the occurrence of wildfire events at the Triassic-Jurassic boundary in Central Iran. The studied outcrop section (the Kamarmacheh Kuh section) is comprised of the Upper Triassic Nayband Formation which passes conformably into the Lower Jurassic Ab-e-Haji Formation with no sharp boundary. Organic petrographical studies reveal a higher concentration of semi-fusinite macerals and microscopic charcoal at the boundary between studied formations. This observation can be an evidence for widespread wildfire events at the Triassic-Jurassic boundary of the studied area. Following these fires, vast areas of land were exposed for erosion and large volumes of clastic sediments were provided due to increased run-off. This agrees well with previous sedimentological and stratigraphical studies suggesting a major change in the depositional conditions from marine to non-marine at the Triassic-Jurassic boundary of the Tabas Basin. These findings can have important implications about paleo-depositional settings of the studied formations and the nature of the associated organic matter.

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Sedimentary environment and provenance of sandstones from the Qadir member in the Nayband Formation, Tabas block, east-central Iran

Boletín de la Sociedad Geológica Mexicana ◽

10.18268/bsgm2021v73n1a140920 ◽

2021 ◽

Vol 73 (1) ◽

pp. A140920

Author(s):

Ehsan Zamaniyan ◽

Mohammad Khanehbad ◽

Reza Moussavi-Harami ◽

Asadollah Mahboubi

Keyword(s):

Continental Margin ◽

Chemical Weathering ◽

Sedimentary Environment ◽

Active Continental Margin ◽

Central Iran ◽

Geochemical Data ◽

Delta Front ◽

Field Evidence ◽

Nayband Formation ◽

The Impact

Qadir Member of Nayband Formation, located in East of Central Iran, has developed to a great extent. Investigation of the lithofacies and sedimentary environment, resulted in identification of the deltaic and marine deposits. Based on field evidence and facies features, Qadir Member consists of two lithofacies, including carbonate and siliciclastic facies. The siliciclastic facies were identified as having four sandstone facies including Sr, Sh, Sp, St, three fine-grained lithofacies, including FI, Fm, Fl (Sr) / Sr (FI) and one coal facies. Also, regarding the field, laboratory studies, and identification of lithofacies, the coastal plain, deltaic (including deltaic plain, proximal delta front, distal delta front, and prodelta) and open marine environments were identified for Qadir Member which is is under the impact of tidal currents. The chemical weathering index (71%) indicated semi-arid to semi-humid conditions and plotting the geochemical data showed the provenance of re-cycling and active continental margin and because of Chemical Index of Alteration, the weathering rate was found to be rather medium to high. The geochemical diagrams also showed a probable source of the intermediate igneous and sedimentary rocks. The active continental margin conditions for this deposit could suggest the Neotethys subduction under Iran’s plate and volcanic activity at the end of Triassic, which coincided with the early Cimmerian orogeny in Alborz and Central East Iranian Microcontinent.

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Geochemistry of shales of the Qadir Member (Nayband Formation, Upper Triassic), East Central Iran (Tabas Block): implications for provenance and palaeogeography

Geological Quarterly ◽

10.7306/gq.1491 ◽

2019 ◽

Author(s):

Ehsan ZAMANIYAN ◽

Mohammad KHANEHBAD ◽

Reza MOUSSAVI-HARAMI ◽

Asadollah MAHBOUBI

Keyword(s):

Upper Triassic ◽

Central Iran ◽

East Central ◽

Nayband Formation

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Norian to Rhaetian scleractinian corals in the Ferdows Patch Reef (Nayband Formation, east central Iran)

Journal of Paleontology ◽

10.1666/12-001.1 ◽

2012 ◽

Vol 86 (5) ◽

pp. 801-812 ◽

Cited By ~ 1

Author(s):

Hannah M. E. Shepherd ◽

George D. Stanley ◽

Fatemeh Amirhassankhani

Keyword(s):

Patch Reef ◽

Scleractinian Corals ◽

Central Iran ◽

East Central ◽

Patch Reefs ◽

Faunal Assemblages ◽

New Information ◽

Nayband Formation ◽

The Subject ◽

Northeast Iran

The Nayband Formation is one of the best known sedimentary units in central Iran. The type section consists of a thick succession of shale, siltstone, reef limestone and sandstone that is subdivided into five distinct members: Gelkan, Bidestan, Hoz-e-Sheykh, Howz-e- Khan and Qadir. Abundant and well-preserved framework-building scleractinian corals are included among the macrofossils of the Nayband Formation; these corals characterize the formation and are the subject of this study. The Hassan-Abad section, located in northeast Iran in Lute Block (northwest of Ferdows city), was chosen for detailed study and sampling. Analysis of sedimentary lithofacies and faunal assemblages in the Bidestan and the Howz-e-khan members indicate both biostromal and biohermal characters for the former shallow-water patch reefs and support a Norian to Rhaetian age. The useful biostratigraphic hydrozoanHeterastridium conglobatumwas studied along with 14 taxa of scleractinian corals:Stylophyllopsis rudis, Distichophyllia norica, Paradistichophyllum dichotomum, Retiophyllia frechi, Retiophyllia norica, Retiophyllia robusta, Chondrocoenia schafhaeutli, Chondrocoenia ohmanni, Astraeomorpha crassisepta, Astraeomorpha confusa, Astraeomorpha minor, Procyclolites triadicus, Pamiroseris rectilamellosa,andEocomoseris ramosa. These fossils clarify the stratigraphy of the Nayband Formation, as well as provide new information on the patch reefs and the framework constructors of these reefs.

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