• Reza Behbahani, Mohammad Ghavidel-syooki, Somayeh Borji, Mahmoud Reza Majidifard, Morteza Yousefi, June 2019.
• DOI: 10.22084/PSJ.2019.17996.1192
In present research, depositional environment of the Ghelli Formation (Late Ordovician) was investigated in NE Alborz Basin (Robat-e-Gharabil Area; Kuh-e-Kurkhud). This study was performed based on field observations, thin sections petrography, sedimentary structures and palynological studies. Utilizing this multidisciplinary approach, four litofacies assemblages were recognized. The Ghelli Formation in studied area comprises alternation of thick to thin shale beds, medium to thin bedded sandstones, sandy limestones, laminated siltstones and diabasic sill. These lithofacies assemblages consist of arkose-subarkose, sandy allochem limestone, siltstone and shale. According to the properties of lithofacies, sedimentary structures and vertical stacking of these lithofacies suggest a storm and wave dominated shelf, wherein the depositional setting evolved from lower shoreface with lower- middle lithofacies (with hummocky cross stratification, truncation surface, parallel lamination and cross lamination) that gradually changed into upper shoreface with upper lithofacies (with swaley cross stratification, wave ripple-mark, parallel lamination, normal grading, wedge-shaped and tabular cross-lamination) which storm and waves induced currents had important roles in sediment reworking and redeposition. Using the Tyson diagram, four palynological facies (III, IVa, V and VII) were identified. Meanwhile, statistical studies on the palynological parameters (percentage of phytoclast, amorphous organic matter and lability parameter) indicate a shallowing upward trend in Ghelli Formation. Comparison of the relative abundance of marine palynomorphs with terrestrial palynological elements indicate less abundance of acritarchs and chitinozoans in comparison with cryptospores and plant fragments which indicate that Ghelli Formation is deposited in shallow marine environment.
Keywords: Ghelli, Formation; Alborz Mountains; Depositional environment; Sedimentary structures; Lithofacies; Palynological facies.
Chronostratigrahy of Acritarchs and Chitinozoans from
upper Ordovician Strata from the Robat-e Gharabil
Area, NE Alborz Mountains, Northern Khorassan
Province: Stratigraphic and Paleogeographic
Implications
M. Ghavidel-Syooki, and S. Borji
Cryptospore and trilete spore assemblages from the Late Ordovician (Katian–Hirnantian) Ghelli Formation, Alborz Mountain Range, Northeastern Iran: Palaeophytogeographic and
palaeoclimatic implications
MOHAMMAD GHAVIDEL-SYOOKI,
Stratigraphic evidence for Hirnantian glaciation in the Alborz Mountain Ranges, northeastern Iran
MOHAMMAD GHAVIDEL-SYOOKI,
Biostratigraphy of Acritarchs and Chitinozoans in Ordovician Strata from the Fazel Abad Area, Southeastern Caspian Sea, Alborz Mountains, Northern Iran: Stratigraphic Implications
MOHAMMAD GHAVIDEL-SYOOKI,
Miospore assemblages from Late Ordovician (Katian- Hirnantian), Ghelli Formation, Alborz Mountain Range North-eastern Iran: Palaeophytogeographic and palaeoclimatic implications
MOHAMMAD GHAVIDEL-SYOOKI,
Cryptospore and trilete spore assemblages from the Late Ordovician (Katian–Hirnantian) Ghelli Formation, Alborz Mountain Range, Northeastern Iran: Palaeophytogeographic and
palaeoclimatic implications
MOHAMMAD GHAVIDEL-SYOOKI,
Mohammad Ghavidel-Syooki1,*, Leonid E. Popov2,*,
Mansoureh Ghobadi Pour3, J. Javier A ´ lvaro4 and Mohammad H. Ehsani1
1Institute of Petroleum Engineering, Technical Faculty of Tehran University, P.O. Box 11365-4563, Tehran, Iran
2Department of Geology, National Museum Cardiff, Cathays Park, Cardiff CF10 3NP, Wales, UK
3Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran
4Centre of Astrobiology (CSIC/INTA), Ctra. de Torrejo´n a Ajalvir km 4, 28850 Torrejo´n de Ardoz, Spain
*Corresponding authors
ABSTRACT: Brachiopods are among the most common components of the Late Ordovician
benthic faunal assemblages recorded in the Faraghan Mountains, Zagros Ranges, Iran. A total
of 19 species referable to 16 genera are identified, including seven new species; namely Drabovia
elegans, Hibernodonta bonehensis, Hedstroemina zakeenensis, Jezercia faraghani, Protomendacella
multicostata, Tafilaltia dargazensis and Tafilaltia seyahouensis. Reported brachiopod assemblages
are oligotaxic (2–3 species per assemblage) to monotaxic. The only exception is the medium diversity
Aegiromena-Hedstroemina Association, with up to ten species, which occurs at the lower part of
the A. nigerica Zone. Low diversity patterns were probably controlled by the palaeogeographical
position of the region in high southern latitudes throughout the Ordovician. Paterula sp. and Iranospirifer
sp. are the only brachiopods documented from the Silurian (Llandovery) Sarchahan Formation.
This paper gives the first detailed report of shelly fossils from the Llandovery ‘hot shale’ of the
Arabian margin of Gondwana. Most of the Katian genera, and many of their species, are shared
with neighbouring high- to mid-latitude peri-Gondwanan margins, including Morocco, Spain,
France, Sardinia and Bohemia.
KEY WORDS: biofacies, biogeography, Faraghan Mountains, Gondwana, Katian, Llandovery
MOHAMMAD GHAVIDEL-SYOOKI, DAVID H. EVANS, MANSOUREH GHOBADI POUR,
LEONID E. POPOV, J. JAVIER ÁLVARO, UTKYR RAKHMONOV, INNA A. KLISHEVICH and
MOHAMMAD H. EHSANI
GHAVIDEL-SYOOKI, M., EVANS, D.H., GHOBADI POUR, M., POPOV, L.E., ÁLVARO, J.J., RAKHMONOV, U., KLISHEVICH, I.A. & EHSANI, M.D., XX.XX.2015.
Late Ordovician cephalopods, tentaculitides, machaeridians and echinoderm columnals from Kuh-e Faraghun, High Zagros, Iran. Alcheringa 39,
XXX–XXX. ISSN 0311-5518.
Late Ordovician (Katian, uppermost Acanthochitina barbata to Armoricochitina nigerica chitinozoan zones) cephalopods, tentaculitides,
machaeridians and echinoderms are documented for the first time from the southern Zagros Ranges. A low-diversity cephalopod fauna
includes Geisonocerina dargazense sp. nov., Isorthoceras sp. cf. I. bisignatum (Barrande) and other undetermined orthoceratides. The presence
of Late Ordovician tentaculitides in the high- to mid-latitude margins of Gondwana has been documented previously, but no examples have
been described in detail. Thus, Costatulites kimi sp. nov., which currently occurs associated with brachiopods characteristic of the Svobodaina
havliceki (brachiopod) Association, represents the earliest undoubted record of tentaculitides in Gondwana. Machaeridians constitute a relatively
common component of the Late Ordovician benthic faunas from the Mediterranean margin of Gondwana, but no previous records
on the Gondwanan Iranian-Arabian segment have been reported. Three echinoderm taxa based on dissociated columnals are documented from
the Armoricochitina nigerica chitinozoan Zone, including Sumsaricystis radiatus Stukalina, Ristnacrinus sp. and Rosulicrinus rosulus
Stukalina.
Mohammad Ghavidel-Syooki Institute of Petroleum Engineering, Technical Faculty of Tehran University, PO
Box 11365-4563, Tehran, Iran; David H. Evans , Natural England, Suite D, Unex House, Bourges Boulevard,
Peterborough PE1 1NG, UK; Mansoureh Ghobadi Pour* , Department of Geology, Faculty of Sciences, Golestan
University, Gorgan, Iran; Leonid E. Popov , Department of Geology, National Museum of Wales, Cathays
Park, Cardiff CF10 3NP, UK; J. Javier Álvaro , Instituto de Geociencias (CSIC-UCM), c/ José Antonio Novais 2, 28040
Madrid, Spain; Utkyr Rakhmonov, Kitab State Geological Reserve, 9 Ipak Yuli Street, Sakhrisabz, Uzbekistan; Inna A. Klishevich, Department of
Historical Geology, Geological Faculty, St Petersburg State University, Universitetskaya Naberezhnaya 7/9, 199034 St Petersburg, Russia
; Mohammad H. Ehsani , Institute of Petroleum Engineering, Technical Faculty of Tehran
University, PO Box 11365-4563, Tehran, Iran. *Also affiliated with Department of Geology, National Museum of Wales, Cathays Park, Cardiff
CF10 3NP, UK. Received 26.2.2015; revised 22.4.2015; accepted 15.5.2015.
Key words: Gondwana, Katian, Seyahou Formation, taxonomy, invertebrates, biogeography.
First reported Late Ordovician trilobites from the High Zagros Ranges, Iran: A biogeographic link between Gondwanan Chinese and Mediterranean faunas
MOHAMMAD GHAVIDEL-SYOOKI,
