G. Daneshian; S. A. Moallemi; A. A. Azad
Abstract
In this research, the Sarvak Formation and lower part of the Surgah Formation in Kabirkuh anticline, southeast Ilam with thickness of 897 m were studied. Prospect of changes in umbilical structures of planktonic foraminifera such as lip, ortico throughout of Albian to Turonian were investigated. The ...
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In this research, the Sarvak Formation and lower part of the Surgah Formation in Kabirkuh anticline, southeast Ilam with thickness of 897 m were studied. Prospect of changes in umbilical structures of planktonic foraminifera such as lip, ortico throughout of Albian to Turonian were investigated. The phylogenic trend shows that lip structure in primary morphogroups gradually replaced by ortico in more developed forms. The statistical analyses showed that the trend of the mentioned changes is comparable with increasing the water depth while a decrease in depth result in the development of lip in studied planktonic foraminifera. According to foraminifera and Oligosteginids, the age of examining succession is late Middle Albian to Late Turonian. The study of different type of morphotype groups in this section indicates that the fauna mostly belong to morphotypes number two and one, and then rarely number three. The studied morphotypes show that the main part of sedimentation carried out in relatively deep marine condition The results show that the Muricohedbergella frequency at lower and middle parts of the Sarvak Formation incompatible with the basin depth decrease that is specified with two decreasing peaks (sea regression). Also Favusella frequency in line with three increasing peaks (sea Transgression), and is a good index for showing the basin depth. In the final part of the sequence, the presence of Whiteinella to increase peaks which are compatible with the basin increasing depth and sea transgressive in studied section.
J. Daneshian; D, Baghbani; S.A. Aghanabati; N. Norouzi
Abstract
Oligocene-Lower Miocene sediments at Nareh section, situated in SW Jahrum consists of limestone, argillaceous limestone, marl and evaporatic sediments with a rich association of planktonic and benthonic foraminifera. In lower part of this succession, the Pabdeh sediments with a thickness of 115m is composed ...
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Oligocene-Lower Miocene sediments at Nareh section, situated in SW Jahrum consists of limestone, argillaceous limestone, marl and evaporatic sediments with a rich association of planktonic and benthonic foraminifera. In lower part of this succession, the Pabdeh sediments with a thickness of 115m is composed of shale, marl and intercalations of argillaceous limestone. The mentioned sediments continue through Late Eocene to Oligocene, which are overlain conformably by the Asmari Formation. The Asmari Formation consists of 250 m limestone and argillaceous limestone of which 210 m belongs to the lower Asmari and 40 m to middle Asmari. Argillaceous limestone and evaporatic-marly sediments of the Gachsaran Formation are overlain by the Asmari Formation. The Gachsaran Formation with a thickness of 510m is composed of three members of Chehel, Champeh and Moll. Pure and thick basal limestones of the Mishan Formation (Guri Member) with a thickness of 302 m, is situated above the Gachsaran Formation. Finally, Bakhtyari conglomerate lies uncomformably over the Mishan Formation. Variety of studied rock units in this section has caused different sedimentary environments, different facies and presence of abundant planktonic and benthonic foraminifera. By studying 203 samples including 193 hard and 10 washed samples, 34 genera and 47 species of benthonic foraminifera and 8 genera and 13 species of planktonic foraminifera, algae, briozoa and different macrofossils fragments were identified. Based on foraminiferal assemblages, the age of the lower part of the Pabdeh Formation is Late Eocene (Priabonian) and the upper part is Early Oligocene and the Asmari Formation is Oligocene (Late Rupelian-Chattian) to Early Miocene (Aquitanian). Also, the Gachsaran Formation belongs to Early Miocene (Aquitanian-Burdigalian) and the age of the Mishan Formation (Guri Member) is Late Miocene (Burdigalian) .On the basis of recognized foraminifera association, Nareh stratigraphical section can be correlated with first to fourth Biozones of biozonation of Adams and Bourgeois (1967) and 54,57,59,61,63 and 64 Biozones of Wynd (1965).
J. Daneshian; D. Baghbani; Kh. Khosrow- Tehrani; L. Fazli
Abstract
In this study, foraminifera of the Ilam and Gurpi Formations, from Kuh-e- Assaluyeh section in east Kangan port in Boushehr province and Ivan well in Persian Gulf are investigated. Ilam Formation in Kuh-e-Assaluyeh section with 30 meter thickness and Ivan well with 68 meter thickness composed of limestone ...
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In this study, foraminifera of the Ilam and Gurpi Formations, from Kuh-e- Assaluyeh section in east Kangan port in Boushehr province and Ivan well in Persian Gulf are investigated. Ilam Formation in Kuh-e-Assaluyeh section with 30 meter thickness and Ivan well with 68 meter thickness composed of limestone and dolomitic limestone. The Ilam Formation in the study sections overlies unconformable the Sarvak Formation and underlies the Gurpi Formation. The Gurpi Formation in Kuh-e-Assaluyeh with 73 meter thickness and Ivan well with 56 meter thickness composed of argillaceous limestone, sandy limestone, shale and limestone. Also the Gurpi Formation in Kuh-e-Assaluyeh section and Ivan well overlies unconformable the Ilam Formation and underlies the Pabdeh Formation. The study of 70 samples from the examined section led to the identification of 13 genera and 19 species of planktonic foraminifera and 12 genera and 12 species of benthonic foraminifera. Planktonic foraminifera are as follow: Heterohelix globolusa, Macroglobigerinelloides ultramicrus, Globotruncanita elevata, Globotruncana bulloides, Globotruncana ventricosa, Muricohedbergella holmdelensis, Heterohelix striata, Macroglobigerinelloides prairiehillensis, Contusotruncana fornicata, spiropelecta sp., Rugoglobigerina rugosa Macroglobigerinelloides bollii, Muricohedbergella monmouthensis, Globotruncana falsostuarti, Gansserina gansseri, Archaeoglobigerina blowi, Globotruncana arca, Contusotruncana contusa, and benthonic foraminifera are as follow : Rotalia sp., Rotalia skourensis, Pseudedomia sp., Minouxia sp., Dicyclina schlumbergeri, Quinqueloculina sp., Marssonella sp., Gavelinela sp., Archaecyclus midorientalis, Ammobaculites sp. On the basis of stratigraphic distribution of index foraminifera, the Ilam Formation belongs to Santonian to Campanian, and the Gurpi Formation in Kuh-e-Assaluyeh section is Campanian to Maastrichtian and in Ivan well is Maastrichtian in age. The studies in Kuh-e-Assaluyeh section let to recognition four foraminifera zone from base to top: Globotruncanita elevata Zone, Globotruncana ventricosa Zone, Globotruncana falsostuarti Zone, Gansserina gansseri Zone. Lacking the main elements of Globotruncanella havanensis and Globotruncana aegyptiaca biozones caused that Globotruncana falsostuarti biozone is introduced on the basis of the first occurances of Globotruncana falsostuarti (at the base) and Gansserina gansseri (at the top). Also in Ivan well, Globotruncana falsostuarti Zone, Gansserina gansseri Zone, Contusotruncana contusa Zone were identified. Abathomphalus mayaroensis in absent at Ivan well and Kuh-e-Assaluyeh. Thus, Abathomphalus mayaroensis biozone is not recognizable, and instead of it Contusoutruncana contusa biozone is introduced. The boundaries of this biozone are identified by the first and last occurrences of Contusoutruncana contuse. Also comparison this study with Biozonation of Wynd, (1965), from base to top: 1-Rotalia sp. 22, Algae assemblage zone, 2- Archaecyclus midorientalis-Pseudedomia sp.assemblage zone, 3- Globotruncanita elevata zone, 4- Globotruncanita stuarti-Pseudotextularia variance assemblage zone. 5- Contusoutruncana contusa zone.
J. Daneshian; M. Shahrabi; M. Akhlaghi
Abstract
75 samples of the Qom Formation in Andabad, northeast Mahneshan, were investigated. The Qom Formation in the examined section with a thickness of 301m, mainly consists of limestone and marl, and disconformably overlies the Lower Red Formation and lies under the sediments of the Upper Red Formation. A ...
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75 samples of the Qom Formation in Andabad, northeast Mahneshan, were investigated. The Qom Formation in the examined section with a thickness of 301m, mainly consists of limestone and marl, and disconformably overlies the Lower Red Formation and lies under the sediments of the Upper Red Formation. A study of foraminifera was led to identifying 42 genera and 70 species of the benthonic and plankthonic foraminifera, which 37 genera and 57 species is reported from this area for the first time. Among them, benthonic foraminifera have more varieties and abundances, and used for biostratigraghy. Based on the identified foraminifera, the Andabad section is comparable to Assemblages Zone 1 and 2 introduced by Adams and Bourgeois. On the basis of occurrence of the index foraminiferal species and their stratigraphic distribution, the age of the Qom Formation in the studied section is Early Miocene (Late Aquitanian to Burdigalian).The assemblage, abundance, and species diversity of foraminifera in the examined samples shows noticeable changes in the paleoenvironmental conditions. The maximum diversity of foraminifera is sixteen species. Based on species diversity, the strata classified to nine assemblages A to I. The abundance of foraminifera in each assemblage indicates that the sediments of the Qom Formation belong to inner shelf environments.
