Investigation of the Early Cretaceous Calcareous Nannofossils in Rumeshtik section (Southeast Sarayan)

Document Type : مقالات پژوهشی

Authors

• Marziyeh Notghi-Moghaddam ¹
• Fatemeh Hadavi ²
• Lida Khodadadi ³

¹ Assistant Professor, Department of Geology, Payame Noor University, Tehran, Iran

² Ferdowsi Mashhad

³ Payame Noor University, Tehran

10.22067/sed.facies.v8i2.41787

Abstract

Introduction
The Lut Block is alsom called the "Median Mass of East Iran". This basin is a region characterized by Jurassic-Cretaceous-Tertiary sequence (Stocklin and Nabavi, 1973). In this research, to determine the age of these sequence in the Sarayan region (Rumeshtik section), a detailed study of calcareous nannofossils under optical microscope was performed. This section, based on the structural classification of Iran, is located in the east margin of Lut block. Previous nannofossils studies of Cretaceous deposits in Lut Block were done by Hadavi et al. (2012) in Gazak section (East Birjand). In the present study, for the first time the nannofloras of the Rumeshtik section were discussed and biostratigraphy of these deposits were presented. The thickness of the studied sequence is 690 meters, and consists of limestone and shale. Ninety eight samples at intervals from 4-10 meter were collected. For the nannofossils, smear-slides were prepared using the technique of Bown and Young (1998) and examined under a light microscope at 1000 magnification by both cross-polarized and phase-contrast methods.

Discussion
In the present study, 33 species belong to 18 genera of calcareous nannofossils in Rumeshtik section were identified. These nannofossils are well to moderately preserved. Some species are abundant in the lowermost part of the studied sections, such as Nannoconus dolomiticus, Nannoc‌onus quadrates and Nannoconus bonetii, while other species are abundant in the uppermost part of the studied sequence such as Nannoconus abundans, Nannoconus circularis, Nannoconus borealis, Lithraphidites bollii and Assipetra terebrodentariu. According to the First occurrence (FO) of marker species, in Rumeshtik section, three calcareous nannofossil biozones (CC3-CC5) were recognized.
Calcicalathina oblongata zone (CC3): This zone explained as the interval from the FO of C. oblongata to FO C. loriei by Sissingh (1977). The age of this zone is Late Valanginian. This is the oldest identified zone in the studied section. Thickness of this biozone is about 370 meter.
Cretarhabdus loriei zone (CC4): This zone explained as the interval from the FO of C. loriei to last occurrence (LO) Speetonia colligata by Sissingh (1977). The age of this zone is Hauterivian. Thickness of this biozone is about 220 meter.
Lithraphidites bollii zone (CC5): This zone explained as the interval from the LO S. colligata to LO C. oblongata by Sissingh (1977). The age of this zone is Late Hauterivian to Barremian. Nannoconus abundans is an index species for Late Hauterivian (Taylor, 1979). Because of the continued presence of C. oblongata, and present of N. abundans, we located lower part of Lithraphidites bollii zone at the end of the studied section. Therefore age of the uppermost part of the studied section is Late Hauterivian. Thickness of this biozone is about 100 meter.
According the calcareous nannofossil biostratigraphy, age of the sequence in the studied region is suggested to be Late Valanginian- Late Hauterivian.
In the current study, in addition to biostratigraphy, investigation of temperature changes was done too. During the Early Cretaceous time, some nannofossils such as Lithraphidites bollii, Nannoconus spp., and Watznaueria barnesae indicate the warm surface water and more related to lower paleolatitudes (Thibault & Gardin, 2007؛ Street & Bown, 2000). The common occurrence of species belong to the genus Watznaueria, Lithraphidites, and Nannoconus are indicative not only of a warm climate, but also of low latitude setting.
Results
In this study, 33 species with relatively well to moderately preservation were identified in the Rumeshtik section. The studied sediments belong to the zones CC3-CC5 of Sissingh (1977). These biozones attribution allow us to access an age of Late Valanginian- Late Hauterivian for the studied section. Index calcareous nannofossil species at the studied sediments indicate that the basin for deposition of these sediments located in low latitude with warm temperature.

Keywords: Calcareous nannofossils; Early Cretaceous; Rumeshtik; Sarayan.

References
Hadavi, F., Khazaei, A.R., Rezaei, F., 2012. Nannostratigraphy of Gazak section in West Lahna- Mahroud (Southeast Birjand). 1st professional congress of sedimentology and stratigraphy, p. 61 (in Persian).
Bown, P.R., Young, J.R., 1998. Techniques. In: Bown, P.R., (ed.), Calcareous Nannofossil Biostratigraphy. British Micropaleontology Society, 16- 28.
Sissingh,W., 1977. Biostratigraphy of cretaceous calcareous nannoplankton. Geologie en Minjbouw. 56:
37-65.
Stocklin, J., Nabavi, M.H., 1973. Tectonic map of Iran. Geological Survey of Iran.
Street, C., Bown, P.R., 2000. Palaeobiogeography of Early Cretaceous (Berriasian-Barremian) calcareous nannoplankton. Marine Micropaleontolology, 39: 265–291.
Taylor, R., 1979. Lower Cretaceous calcareous nannofossils. In: Lord, A.R. (ed.), A stratigraphical index of calcareous Nannofossils. British Micropaleontology Society, 40-80.
Thibult, N., Gardin, S., 2007. The late Maastrichtian nannofossil record of climate change in the South Atlantic DSDP Hole 525A. Marine Micropaleontology, 65: 163-184.

Keywords

• Calcareous Nannofossils
• Early Cretaceous
• Rumeshtik
• Sarayan

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References

آقانباتی، ع.، 1383. زمین‌شناسی ایران. سازمان زمین‌شناسی و اکتشافات معدنی کشور، ۵۸۶ ص.

خدادادی، ل.، هادوی، ف.، رحیمی، ب.، 1390. نانواستراتیگرافی و پالئواکولوژی گذر سازندهای شوریجه ـ تیرگان در دو برش مزدوران و کلات. پژوهشهای چینه‌نگاری و رسوب‌شناسی، 4: 85-100.

هادوی، ف.، خزاعی، ا.، رضایی، ف.، 1390. نانواستراتیگرافی برش گازک واقع در غرب تاقدیس لهنا ـ ماهرود (جنوب شرق بیرجند). نخستین کنگره تخصصی رسوب‌شناسی و چینه‌شناسی ایران، ص 61.

Alavi Naini, M., & Behruzi, A. 1981. Geological map of Qayen, scale 1:100,000. Geological Survey of Iran.

Barrera, E., & Savin, S.M., 1999. Evolution of Campanian–Maastrichtian marine climates and oceans. In: Barrera, E., & Johnson, C.C., (eds.), Evolution of the Cretaceous Ocean-Climate System. Geological Society of America, Special, Boulder, 332: 245–282.

Barrera, E., Savin, S.M., Thomas, E., & Jones, C.E., 1997. Evidence for thermohaline- circulation reversals controlled by sea level change in the latest Cretaceous. Geology, 25: 715–718.

Bown, P.R., & Young, J.R., 1998. Techniques. In: Bown, P.R., (ed.), Calcareous Nannofossil Biostratigraphy. British Micropaleontology Society, 16- 28.

Bown, P.R., 1999. Calcareous nannofossil biostratigraphy. Klower Academic publication, 315 p.

Eshet, Y., Moshkovitz, S., Habib, D., Benjamini, C., & Margaritz, M., 1992. Calcareous nannofossil and dinoflagellate stratigraphy across the Cretaceous/Tertiary boundary at Hor Hahar, Israel. Marine Micropaleontology, 18: 199–228.

Hadavi, F., & Khodadadi, L., 2013. Nannostratigraphy and palaeoecology of uppermost Mozduran Formation in the Kopeh-Dagh range (NE Iran). Arabian Journal of Geosciences, 7: 1879-1889.

Haq, B.U., 1978. Calcareous nannoplanktone. In: Haq, B., & Boersma, A., (eds.), Introduction to Marine Micropaleontology. Elsevier Science, pp.79-107.

Kominz, M.A., 2001. Sea level variations over geologic time. Western Michigan University, Academic press, pp.2605-2613.

Lees, J.A., 2003. Calcareous nannofossil biogeography illustrates palaeoclimate change in the Late Cretaceous Indian Ocean. Cretaceous Research, 23: 537-634.

Li, L., & Keller, G., 1999. Variability in Late Cretaceous and deep waters: evidence from stable isotopes. Marine Geology, 161: 171-190.

Lottaroli, F., & Catrullo, D., 2000. The calcareous nannofossil biostratigraphic framework of the Late Maastrichtian - Danian North Sea chalk. Marine Micropaleontology, 39: 239–263.

Markevich, V., & Bugdaeva, E., 2007. Climate during the Santonian to Danian based on Palynological data (Amur River Basin). Daqing, China, 22: 42-45.

Norris, R.D., Kroon, D., Huber, B.T., & Erbacher, J., 2001. Cretaceous-Palaeogene Ocean and climate change in the subtropical North Atlantic. In: Norris, R. D., Kroon, D., & Klaus, A. (eds.), North Atlantic Palaeogene and Cretaceous Paleoceanography. Geological Society of London, 183: 1-22.

Nowroozi, A.A., 1972. Focal mechanism of earthquakes in Persia, Turkey, West Pakistan and Afghanistan and plate tectonics of the Middle East. Bulletin of Seismological Society America, 62 (3): 823- 850.

Perch-Nielsen, K., 1979. Calcareous nannofossils from the Cretaceous between the North Sea and the Mediterranean. lUGS Series A, 6: 223-272.

Perch-Nielsen, K., 1983. Recognition of Cretaceous stage boundaries by means of calcareous nannofossils. In: Birkelund, T., et al., (eds.), Symposium on Cretaceous Stage Boundaries, Copenhagen, Abstracts, 152-156.

Perch-Nielsen, K., 1985. Mesozoic Calcareous Nannofossils. In: Bolli, H.M., Saunders, J.B., & Perch-Nielsen, K. (eds.), Plankton Stratigraphy. Cambridge University Press, 329-426.

Pospichal, J.J., & Wise, J.R., 1990. Calcareous nannofossils across the K–T boundary. ODP Hole 690C, Maud Rise, Weddell Sea. Procceding Ocean Drilling Program. 113: 515– 532.

Roth, P.H., & Bowdler, J.L., 1981. Middle Cretaceous calcareous nannoplankton biogeography and paleoceanography of the Atlantic Ocean. SEPM Special Publication. 32: 517–546.

Roth, P.H., 1978. Cretaceous nannoplankton biostratigraphy and oceanography of the Northwestern Atlantic Ocean. Initial Reports Deep Sea drilling Project, 44: 731-759.

Roth, P.H., 1986. Mesozoic palaeoceanography of the North Atlantic and the Tethys Oceans. In: Summerhayes, C.P., & Shackelton, N.J., (eds). SEPM Special Publication. 32: 517– 546.

Sissingh,W., 1977. Biostratigraphy of cretaceous calcareous nannoplankton. Geologie en Minjbouw. 56: 37-65.

Stocklin, J., & Nabavi, M.H., 1973. Tectonic map of Iran. Geological Survey of Iran.

Stocklin, J., 1968. Structural history and tectonics of Iran: A review American Association Petrology. Geologists Bulletin, 52 (7): 1229-1258.

Stocklin, J., 1972. Lexique Stratigraphique International. Geological Survey of Iran, Fascicule 9b, Iran.

Street, C., & Bown, P.R., 2000. Palaeobiogeography of Early Cretaceous (Berriasian-Barremian) calcareous nannoplankton. Marine Micropaleontolology, 39: 265–291.

Taylor, R., 1979. Lower Cretaceous calcareous nannofossils. In: Lord, A.R. (ed.), A stratigraphical index of calcareous Nannofossils. British Micropaleontology Society, 40-80.

Thibault, N., & Gardin, S., 2006. Maastrichtian calcareous nannofossil biostratigraphy and paleoecology in the Equatorial Atlantic (Demerara Rise, ODP Leg 207 Hole 1258A). Reviews Micropaleontology, 49: 199-214.

Thibult, N., & Gardin, S., 2007. The late Maastrichtian nannofossil record of climate change in the South Atlantic DSDP Hole 525A. Marine Micropaleontology, 65: 163-184.

Thierstein, H.R., 1976. Mesozoic calcareous nannoplankton biostratigraphy of marine sediments. Marine Micropaleontology, 1: 325-362.

Thierstein, H.R., 1981. Late cretaceous nannoplankton and the change at the C/T boundary. SEPM Special Publication, pp.355-394.

Watkins, D.K., 1996. Upper Cretaceous calcareous nannofossil biostratigraphy and paleoecology of the Southern Oceon. In: Moguilesvky, A., & Whatley, R., (eds.), Microfossils and Oceanic Environments. University of Wales Aberystwyth Press, pp.355-381.

Williams, J.R. & Bralower, T.J., 1995. Nannofossil assemblages, fine fraction stable isotopes, and the paleoceanography of the Valanginian - Barremian (Early Cretaceous) North Sea Basin. Paleoceanography, 10: 815- 839.

Wise, S.W., 1983. Mesozoic and Cenozoic calcareous nannofossils recovered by Deep Sea Drilling Project Leg 71in the Falkland Plateau Region, Southwest Atlantic Ocean. Initial Reports Deep Sea drilling Project, 71: 481 -550.