The Asmari Formation is a geological formation in western Iran. Located in the western Zagros Mountains, it is a carbonate formation that largely consists of limestone, dolomitic limestone, dolomite, and marly limestone.[1] There are also smaller amounts of anhydrite, lithic sandstone, and limey sandstone.[1] The formation dates to the Oligocene and Miocene periods and is a major hydrocarbon reserve.[2][3] It has been producing oil since the 1930s.[4] It also forms a major aquifer, which discharges at various springs in the Zagros region.[5]

The Asmari Formation's basic biostratigraphy was established in the 1950s and it was formally described in 1965.[4] It consists of carbonate platforms that were formed in 6 distinct stages.[3] The formation is named after the Asmari Mountains southeast of Masjed Soleyman, and its type sample was taken from the Tang-e Gel Torsh in these mountains.[6]

The Asmari Formation was deposited at a time when the Tethys Ocean was finally closing and the Zagros Mountains were first rising.[6] During this period, the region was a shallow ocean gradually getting less deep.[6] By the time of the succeeding Gachsaran Formation, this process had culminated in the sea shrinking to lagoons.[6]

In the southwestern Zagros, the Asmari Formation sits on top of the Pabdeh Formation.[1] In the Fars and Luristan regions, the Asmari Formation sits on top of the Jahrum and Shahbazan Formations.[1] The Asmari Formation is thickest in the northeastern part of the Dezful Embayment.[1]

The formation has various microfossils including planktonic foraminifera, echinoids, red algae, ostracoda, and oncoids.[3] Individual species include Globigerina, Turborotalia cerroazulensis, Hantkenina, Nummulites, Lepidocyclina, Miogypsina, Elphidium, Peneroplis farsenensis, and Borelis melo curdica and Borelis melo melo.[4]

See also

References

  1. 1 2 3 4 5 Vaziri-Moghaddam, Hossein; Seyrafian, Ali; Taheri, Azizolah; Motiei, Homayoon (2009). "Oligocene–Miocene ramp system (Asmari Formation) in the NW of the Zagros basin, Iran: Microfacies, paleoenvironment and depositional sequence". Revista Mexicana de Ciencias Geológicas. 27 (1). Retrieved 26 October 2022.
  2. ↑ Abyat, Yasin; Abyat, Ahmad; Abyat, Abdolkhalegh (2019). "Microfacies and depositional environment of Asmari formation in the Zeloi oil field, Zagros basin, south-west Iran". Carbonates and Evaporatives. 34 (1583–93): 1583–1593. doi:10.1007/s13146-019-00507-1. S2CID 155218201.
  3. 1 2 3 Khalili, Ardavan; Vaziri-Moghaddam, Hossein; Arian, Mehran; Seyrafian, Ali (2021). "Carbonate platform evolution of the Asmari Formation in the east of Dezful Embayment, Zagros Basin, SW Iran". Journal of African Earth Sciences. 181: 104229. Bibcode:2021JAfES.18104229K. doi:10.1016/j.jafrearsci.2021.104229.
  4. 1 2 3 Laursen, G.V.; Monibi, S.; Allan, T.L.; Pickard, N.A.H.; Hosseiney, A.; Vincent, B.; Hamon, Y.; van Buchem, F.S.P.; Moallemi, A.; Druillion, G. (2009). "The Asmari Formation Revisited: Changed Stratigraphic Allocation and New Biozonation". Shiraz. 1st International Petroleum Conference and Exhibition Shiraz 2009. 4. doi:10.3997/2214-4609.20145919. ISBN 978-90-73781-65-8. Retrieved 26 October 2022.
  5. ↑ Karimi, Haji; Raeisi, Ezzat; Bakalowicz, Michel (2005). "Characterising the main karst aquifers of the Alvand basin, northwest of Zagros, Iran, by a hydrogeochemical approach". Hydrogeology Journal. 13 (5): 787–99. doi:10.1007/s10040-004-0350-4. S2CID 128560963. Retrieved 20 October 2022.
  6. 1 2 3 4 Dehghanian, Mohammadsadegh (March 2021). "Bio-Sequence Stratigraphy of Asmari Formation in the Southeast of Norabad (Zagros Basin, SW Iran)" (Preprint). doi:10.21203/rs.3.rs-315337/v1. S2CID 233677820. Retrieved 26 October 2022. {{cite journal}}: Cite journal requires |journal= (help)

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