Stratigraphy and Palaeontology
A. Abdolnia; I. Maghfouri Moghaddam; D. Baghbani
Abstract
The Shahbazan Formation deposited in the Lorestan foreland basin and northeastern part of Dezful embayment zone during the Middle-Late Eocene age. In order to study the stratigraphy of the Shahbazan Formation, four surface sections of this formation in northeastern flank of Langar anticline, southeastern ...
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The Shahbazan Formation deposited in the Lorestan foreland basin and northeastern part of Dezful embayment zone during the Middle-Late Eocene age. In order to study the stratigraphy of the Shahbazan Formation, four surface sections of this formation in northeastern flank of Langar anticline, southeastern flank of Chenareh anticline, northeastern flank of Maleh Kuh anticline and southwestern flank of Poshte-Jangal anticline, have been selected. The Shahbazan Formation in Langar and Chenareh sections is composed of limestone with intercalation of dolomite. In other parts of the Lorestan such as Maleh kuh and Poshte Jangel, it consists of dolomite and intercalations of limestons. In these areas, the Shahbazan and Asmari formations form a prominent topographic unit and separating their boundary is often difficult to place, thus making it necessary to map the two formations as one unit. In this case, the two names are hyphenated as Shahbazan- Asmari Formation. According to study of benthic foraminifera in Chenareh and Langar sections, two biozone have been distinguished. The age of the Shahbazan Formation in these areas is determined as Middle- Late Eocene (Bartonian- Priabonian). In the Maleh Kuh section, the lower part of the Shahbazan- Asmari Formations is dolomitic but in the upper part it contains limestone beds with foraminifera that belong to two assemblage zones, in Aquitanian- Burdigalian age. In the Poshte Jangal section, the lower and middle parts of Shahbazan- Asmari formations are dolomitic but the upper part contains limestone beds with rare foraminifera which have been reported at the Chattian- Burdigalian beds of the Asmari Formation.
F Chegeni; D Baghebani; S.H Vaziri; T Mohtat; N Kohansal Ghadimvand
Abstract
For the purpose of biozonation of the Pabdeh Formation (Middle-Upper Eocene) based on planktonic foraminifera, a stratigraphic section in the southern slope of the Mishan Mountain and another in the Eshgar Mountain were studied. The thickness of these sections is 162.5 and 150 meters, respectively. The ...
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For the purpose of biozonation of the Pabdeh Formation (Middle-Upper Eocene) based on planktonic foraminifera, a stratigraphic section in the southern slope of the Mishan Mountain and another in the Eshgar Mountain were studied. The thickness of these sections is 162.5 and 150 meters, respectively. The Pabdeh Formation in the southern slope of the Mishan Mountain consists of marl, marly limestone, shale and limestone, and in the Eshgar Mountain includes alternating cream limestone and thin-bedded marl. In this study, most of the identified microfauna are Planktonic foraminifera. Identified Planktonic and benthic foraminifers in the southern slope of the Mishan Mountain include 18 genera and 8 species, and in the Eshgar Mountain include 21 genera and 10 species. Also four biozones are introduced of which one belongs to the Mishan Mountain and three belong to the Eshgar Mountain as follow: Hantkenina nuttalli Range Zone; Hantkenina nuttalli Turborotalia cerro-azulensis Interval Zone; Turborotalia cerro-azulensis Range Zone; Turborotalia cerro-azulensis/ Hantkenina sp. Assemblage Zone.
M Joudaki; D Baghbani; S.A Aghanabati; B Soleimani; H Asilian; B Ariafar
Abstract
In order to biostratighraphy and to discover relationships between biozones of the Oligocene and lower Miocene strata in Zagros foreland basin, Zagros simply folded belt and High Zagros area, 10 stratigraphic sections along a transect from well "A" in Persian Gulf to Semirum section in High Zagros ...
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In order to biostratighraphy and to discover relationships between biozones of the Oligocene and lower Miocene strata in Zagros foreland basin, Zagros simply folded belt and High Zagros area, 10 stratigraphic sections along a transect from well "A" in Persian Gulf to Semirum section in High Zagros were investigated. The study of more than 1500 thin sections resulted in identification of 32 genera and 54 species of benthonic foraminifera belonging to nine genera and 15 species of planktonic foraminifera. The recorded assemblages led to establishment of six biozones ranging in age from Oligocene to Early Miocene. Biostratighraphic correlation yielded clarification of relationship between biozones and sedimentary trends and discontinuities of the Oligocene and lower Miocene in Zagros basin in the areas.
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).
Kh. Khosrotehrani; D. Baghbani; F. Keshani; M. Omrani
Abstract
In order to study Biostratigraphy of Cenomanian – Late Campanian deposits (upper part of Sarvak Fm.,Ilam Fm. and lower part of Gurpi Fm.), kuhe Assaluyeh stratigraphic section selected. Sediments of this interval consist of limestone, argillaceous limestone and marl with thickness of 162 m. In ...
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In order to study Biostratigraphy of Cenomanian – Late Campanian deposits (upper part of Sarvak Fm.,Ilam Fm. and lower part of Gurpi Fm.), kuhe Assaluyeh stratigraphic section selected. Sediments of this interval consist of limestone, argillaceous limestone and marl with thickness of 162 m. In this section Ilam Fm. in age of Santonian overlies Sarvak Fm. disconformably and is underlain by Gurpi Fm. conformably. By micropaleontological study on 55 thin sections, 5 genus and 9 species of planktonic and 16 genus and 13 species of benthic foraminifers were identified. Among distinguished foraminifers, Rotaliidae family forms were studied carefully and revised. It should be mentioned that, 5 genus and 6 species of benthic foraminifers (Rotaliid forms) were recognized in Iran for the first time (in Assaluyeh section) which consist of: Rotorbinella mesogeensis,Rotorbinella campaniola,Iberorotalia reicheli,Calcarinella schaubi, Pararotalia tuberculifera and Pyrenerotalia longifolia. Santonian age was determined for Ilam Fm. by identified foraminifers. In studied section, stratigraphy development of benthic foraminifers was compared by Martinez Biozones Martinez (2007). This biozones were presented on the base of Rotaliid forms for Pyrenees area in Spain. By this comparison, four biostratigraphy zones for upper part of Sarvak and Ilam Fm. are suggested.
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.