scholarly journals Microfacies, depositional environment and sequence stratigraphy of the Asmari Formation at Nil anticline area (north-east of Dehdasht)

2017 ◽  
Vol 3 (1) ◽  
pp. 45-60
Author(s):  
ali ansari ◽  
h vazirimoghadam ◽  
a taheri ◽  
◽  
◽  
...  
Author(s):  
Bahman Kiani Shavandi ◽  
Vahid Ahmadi

<div><p><em>Asmari formation in Maroon Oilfield is made up of fossil-bearing limestone, dolomitic limestone, argillaceous limestone, sandstone and shale. It is the main reservoir rock for multiple oil wells of Zagros. The formation in Maroon Oilfield dates back to Oligocene(Rupelian – Burdigalian). In the present study, sequence stratigraphy and depositional environment of Asmari Reservoir Formation located in Maroon Oilfield are studied through well-logging data. The lower limit of Asmari Formation in the studied area is Pabede Formation and its upper limit is Gachsaran Formation. The lower limit between Asmari and Pabede formations and upper limit between Asmari and Gachsaran formations are not continuous and signs of discontinuity are observed in them. The field, macroscopic and microscopic studied and determination of percentage and type of allochem and orthochem elements led to identification of 17 carbonate and clastic facies in Asmari Formation. In the section, 6 depositional sequences were identified and labeled as sequence 1-6. The sequence limits are all of SB2 type with exception of Sequence 6 which is SB1. </em></p></div>


Facies ◽  
2005 ◽  
Vol 52 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Hossein Vaziri-Moghaddam ◽  
Masoud Kimiagari ◽  
Azizolah Taheri

Author(s):  
Feiko Kalsbeek ◽  
Lilian Skjernaa

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kalsbeek, F., & Skjernaa, L. (1999). The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 103-112. https://doi.org/10.34194/ggub.v181.5118 _______________ The 2800 Ma Atâ intrusive complex (elsewhere referred to as ‘Atâ granite’ or ‘Atâ tonalite’), which occupies an area of c. 400 km2 in the area north-east of Disko Bugt, was emplaced into grey migmatitic gneisses and supracrustal rocks. At its southern border the Atâ complex is cut by younger granites. The complex is divided by a belt of supracrustal rocks into a western, mainly tonalitic part, and an eastern part consisting mainly of granodiorite and trondhjemite. The ‘eastern complex’ is a classical pluton. It is little deformed in its central part, displaying well-preserved igneous layering and local orbicular textures. Near its intrusive contact with the overlying supracrustal rocks the rocks become foliated, with foliation parallel to the contact. The Atâ intrusive complex has escaped much of the later Archaean and early Proterozoic deformation and metamorphism that characterises the gneisses to the north and to the south; it belongs to the best-preserved Archaean tonalite-trondhjemite-granodiorite intrusions in Greenland.


Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.


2020 ◽  
Author(s):  
Samsideen Ajala ◽  
◽  
Raphael Gottardi ◽  
Chioma Onwumelu ◽  
Davide Oppo

2021 ◽  
Vol 173 ◽  
pp. 103952
Author(s):  
Mohsen Liaghat ◽  
Mohammad Hossein Adabi ◽  
Rudy Swennen ◽  
Zahra Mohammadi ◽  
Hassan Alijani

2021 ◽  
Author(s):  
Mohammadsadegh Dehghanian

Abstract Asmari Formation is the thick sequence of carbonate sediment in the range of Oligocene-Miocene which is deposited in the foreland basins of the Zagros and is considered as the original and most famous reservoir rock of Zagros basin. To study of lithostratigraphic units and sequence stratigraphy of this Formation, the section in the southeast of Norabad was selected. Field study indicated that Asmari Formation possessed the thickness of 401.5m and included 9 lithostratigraphic units. According to the study of microfacies, Stacking pattern and identification of main sequence level, three depositional sequences including two-second order and one-third order sequence were recognized. The sea-level curve in the studied section indicated that it was correspondence to the global sea level curve. These facies deposited in five environmental sedimentations as follow Open Sea Shelf (Fore Barrier), Bar, Lagoon, Back bar shelf, and Shoal. The environment is part of a carbonate platform that has been formed on an open shelf. In addition, according to the Study of foraminifer dispersion pattern the range of Asmari Formation in Norabad was suggested to be Oligocene (Rupelian- Chattian) to lower Miocene (Aquitanian- Burdigalian).


2006 ◽  
Vol 11 ◽  
pp. 33-52
Author(s):  
Jean-François Moyen ◽  
Gordon R. Watt

The area north-east of Kangaatsiaq features polyphase grey orthogneisses, supracrustal rocks and Kangaatsiaq granite exposed within a WSW–ENE-trending synform. The supracrustal rocks are comprised of garnet-bearing metapelites, layered amphibolites and layered, likewise grey biotite paragneisses. Their association and geochemical compositions are consistent with a metamorphosed volcano-sedimentary basin (containing both tholeiitic and calc-alkali lavas) and is similar to other Archaean greenstone belts. The Kangaatsiaq granite forms a 15 × 3 km flat, subconcordant body of deformed, pink, porphyritic granite occupying the core of the supracrustal synform, and is demonstrably intrusive into the amphibolites. The granite displays a pronounced linear fabric (L or L > S). The post-granite deformation developed under lower amphibolite facies conditions (400 ± 50°C), and is characterised by a regular, NE–SW-trending subhorizontal lineation and an associated irregular foliation, whose poles define a great circle; together they are indicative of highly constrictional strain. The existence of a pre-granite event is attested by early isoclinal folds and a foliation within the amphibolites that is not present in the granite, and by the fact that the granite cuts earlier structures in the supracrustal rocks. This early event, preserved only in quartz-free lithologies, resulted in high-temperature fabrics being developed under upper amphibolite to granulite facies conditions.


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