Sedimentary facies and depositional environments of the Oligocene–early Miocene marine Qom Formation, Central Iran Back-Arc Basin, Iran (northeastern margin of the Tethyan Seaway)

2020 ◽  
Vol 35 (1) ◽  
Author(s):  
Ebrahim Mohammadi
Keyword(s):  
Sedimentary Facies ◽  
Depositional Environments ◽  
Central Iran ◽  
Early Miocene ◽  
Qom Formation ◽  
Tethyan Seaway ◽  
Back Arc

scholarly journals Microfacies and sedimentary environments of the late Oligocene-early Miocene Qom Formation of the Gooreh Berenji region (Jandaq area, central Iran)

GeoArabia ◽  
2007 ◽  
Vol 12 (4) ◽  
pp. 41-60
Author(s):  
Shakeri Alireza ◽  
Douraghinejad Jalal ◽  
Moradpour Mehran
Keyword(s):  
Oil And Gas ◽  
Patch Reef ◽  
Depositional Environments ◽  
Central Iran ◽  
Source Rocks ◽  
Early Miocene ◽  
Petrographic Analysis ◽  
Late Oligocene ◽  
Qom Formation ◽  
Wide Range

ABSTRACT The late Oligocene-early Miocene Qom Formation in the Central Iran Basin contains oil and gas in the Alborz and Sarajeh fields. Organic geochemical analyses in previous studies indicated that the hydrocarbons migrated from deeper source rocks, likely of Jurassic age. In the Central Iran Basin, the Qom Formation is 1,200 m thick and is bounded by the Oligocene Lower Red Formation and the middle Miocene Upper Red Formation. In previous studies, the Qom Formation was divided into nine members designated from oldest to youngest: a, b, c to c4, d, e and f, of which “e” is 300 m thick and constitutes the main reservoir. Our study focused on a Qom section located in the Gooreh Berenji region of central Iran which is 294 m thick. The lower part of the formation was not deposited, and only the following four members of early Miocene age (Aquitanian and Burdigalian) were identified between the Lower and Upper Red formations: “c2”? (mainly greyish to greenish gypsiferous marls); “d” (thin- to thick-bedded anhydrite with intercalation of thin-bedded sandstone); “e” (argillaceous or sandy limestone); and “f” (fine-grained coral and bryozoan boundstone). In contrast to the Central Iran Basin, the “e” member in Gooreh Berenji is only 15 m thick and does not have a good reservoir potential. A detailed petrographic analysis of the Gooreh Berenji section resulted in the identification of 13 microfacies (MF) that were interpreted in terms of their depositional environments according to the following categories: MF1 (sabkha), MF2 (intertidal river channel), MF3 (lower intertidal), MF4 (peritidal), MF5 (supratidal), MF6 and MF7 (shallow restricted lagoon), MF8 and MF10 (proximal open-marine), MF9 (leeward lagoon), MF11 (shoal), MF12 (reef and patch reef formed within lagoon), and MF13 (open-marine). The Qom Formation constitutes a regional transgressive-regressive sequence that is bounded by two continental units (Lower and Upper Red formations). The transgression started from the south in the late Oligocene and by the early Miocene the sea covered all of central Iran. In the Gooreh Berenji area, carbonate deposition occurred on a shallow-marine ramp. The presence of a wide range of lagoonal facies indicates that reefal facies (“f”) developed in a narrow elongated strip away from the shoreline.

scholarly journals FACIES ANALYSIS AND STRATIGRAPHIC SEQUENCE ARCHITECTURE IN A BACK-ARC BASIN IN CENTRAL IRAN: A CASE STUDY FROM THE EARLY MIOCENE OF THE QOM FORMATION

2020 ◽  
Vol 17 (35) ◽  
pp. 135-154
Author(s):  
Sara HASSANZADEH ◽  
Mohammad Hossein ADABI ◽  
Nader KOHANSAL GHADIMVAND ◽  
Mahmood JALALI ◽  
Mohammad Ali ARIAN
Keyword(s):  
Sedimentary Facies ◽  
Field Studies ◽  
Central Iran ◽  
Early Miocene ◽  
Arabian Plate ◽  
Stratigraphic Sequence ◽  
Depositional Sequences ◽  
Qom Formation ◽  
Early Oligocene ◽  
System Tracts

Marine deposits of the Qom Formation, which is an important gas reservoir in Central Iran with the age of Early Oligocene to Early Miocene, is studied to determine facies, sedimentary paleoenvironment, and depositional sequences. The primary lithology is limestone, which is accompanied by a conglomerate, sandy marl, marl, and sandy limestone. Based on siliciclastic content, textural analysis, and the biotic constituents, ten facies have been identified. These facies belong to five depositional settings, including delta, a tidal inlet, lagoon, shoal, and open marine. According to the absence of continuous and large barrier reefs, gradual vertical variation in facies from the transitional environment (delta) to shallow open marine, the absence of oncoid, pisoid and aggregate grains that are mostly present in rimmed carbonate shelf environments, the absence of calciturbidites and slump and slide structures, the Qom Formation has been deposited in a homoclinal ramp setting (inner, middle and outer ramp). Field studies and vertical facies variation architecture in the framework of depositional system tracts led to the recognition of two 3rd order depositional sequences in the Early Miocene (Aquitanian) time. Sedimentary facies in the Qom Formation that mainly occurred in the middle ramp setting reveal a mostly aggredational stacking pattern in depositional sequences. The Early Miocene sequences stratigraphic architecture of the Qom Formation based on correlation charts are similar to the regional sequences of the Arabian plate and Zagros basin.

scholarly journals Reconstruction of the depositional sedimentary environment of Oligocene deposits (Qom Formation) in the Qom Basin (northern Tethyan seaway), Iran

Geologos ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 93-111
Author(s):  
Amrollah Safari ◽  
Hossein Ghanbarloo ◽  
Parisa Mansoury ◽  
Mehran Mohammadian Esfahani
Keyword(s):  
Sea Level ◽  
Sedimentary Environment ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
Third Order ◽  
Depositional Sequences ◽  
Qom Formation ◽  
Tethyan Seaway ◽  
Qom Basin ◽  
Global Sea Level

AbstractDuring the Rupelian–Chattian, the Qom Basin (northern seaway basin) was located between the Paratethys in the north and the southern Tethyan seaway in the south. The Oligocene deposits (Qom Formation) in the Qom Basin have been interpreted for a reconstruction of environmental conditions during deposition, as well as of the influence of local fault activities and global sea level changes expressed within the basin. We have also investigated connections between the Qom Basin and adjacent basins. Seven microfacies types have been distinguished in the former. These microfacies formed within three major depositional environments, i.e., restricted lagoon, open lagoon and open marine. Strata of the Qom Formation are suggested to have been formed in an open-shelf system. In addition, the deepening and shallowing patterns noted within the microfacies suggest the presence of three third-order sequences in the Bijegan area and two third-order depositional sequences and an incomplete depositional sequence in the Naragh area. Our analysis suggests that, during the Rupelian and Chattian stages, the depositional sequences of the Qom Basin were influenced primarily by local tectonics, while global sea level changes had a greater impact on the southern Tethyan seaway and Paratethys basins. The depositional basins of the Tethyan seaway (southern Tethyan seaway, Paratethys Basin and Qom Basin) were probably related during the Burdigalian to Langhian and early Serravallian.

Carbonate Sequence Stratigraphy of a Back-Arc Basin: A Case Study of the Qom Formation in the Kashan Area, Central Iran

2007 ◽  
Vol 81 (3) ◽  
pp. 488-500 ◽  
Author(s):  
XU Guoqiang ◽  
ZHANG Shaonan ◽  
LI Zhongdong ◽  
SONG Lailiang ◽  
LIU Huimin
Keyword(s):  
Sequence Stratigraphy ◽  
Central Iran ◽  
Qom Formation ◽  
Carbonate Sequence ◽  
Back Arc
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