Stratigraphy and Palaeontology
Hajar Mashayekh; Massih Afghah; Mahnaz Parvaneh- Nejad Shirazi
Abstract
In order to biostratigraphic studies of Gurpi Formation, a section was selected in the north-east of Noorabad city in Fars. Structurally, this section is located in the folded-thrust zone of Zagros and geographically in the Fars zone (coastal Fars). The Gurpi Formation is extended of 229 meters in thickness, ...
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In order to biostratigraphic studies of Gurpi Formation, a section was selected in the north-east of Noorabad city in Fars. Structurally, this section is located in the folded-thrust zone of Zagros and geographically in the Fars zone (coastal Fars). The Gurpi Formation is extended of 229 meters in thickness, contains limestone, shale, marly limestone and argillaceous limestone. Its lower boundary with Sarvak Formation and its upper contact with Pabdeh Formation are discontinuous. The study conducted on foraminiferal biostratigraphy in this section led to the identification of 20 species belonging to 7 genera of planktonic foraminifera. Based on the stratigraphic distribution of the planktonic foraminifera, five biozones are determined which correspond with global biozonation. Described biozones are comprised of: 1-Globotruncanita elevata Partial range zone; 2-Globotruncana ventricosa Interval zone; 3-Radotruncana calcarata Total range zone; 4-Gansserina gansseri Interval zone; 5-Contusotruncana contusa, Contusotruncana walfischensis, Globotruncanita conica Assemblage zone. Based on these biozones, the age of Gurpi Formation is assigned to early Campanian to late Maastrichtian. The absence of the Marginotruncana and Dicarinella asymetrica in the lower part of the Gurpi Formation indicates of the Santonian-Campanian boundary and the determination of the early Early Campanian age for the base of this Formation.
Stratigraphy and Palaeontology
faeze Amiri; E Zarei
Abstract
The Gurpi formation in Bishe-deraz Section, south of Ilam, consists of 201m marl with intercalations of limy marl with two formal members of Seymareh (Lopha) and Emam-Hasan. The formation overlies the Ilam Formation and is gradationally overlain by the purple shales of the basal part of the Pabdeh Formation. ...
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The Gurpi formation in Bishe-deraz Section, south of Ilam, consists of 201m marl with intercalations of limy marl with two formal members of Seymareh (Lopha) and Emam-Hasan. The formation overlies the Ilam Formation and is gradationally overlain by the purple shales of the basal part of the Pabdeh Formation. The Gurpi Formation was divided to 9 biozone on the basis of planktonic foraminifera which almost are cosmopolitan and consist of: 1- Radotruncana calcarata Taxon-Range Zone. 2- Globotruncanita stuartiformis Partial-Range Zone. 3- Globotruncana aegyptiaca Interval Zone. 4-Gansserina gansseri Interval Zone. 5- Contusotruncana contusa Interval Zone. 6- Abathomphalus mayaroensis Interval Zone. 7- Praemurica uncinata Interval Zone. 8- Morozovella angulata Interval Zone. 9- Globanomalina pseudomenardii Interval Zone. The formation was deposited from upper Campanian through late Paleocene (Selandian-Thanetian?) according to the planktonic foraminifera recorded. A distinct hiatus was confirmed at the Cretaceous-Paleogene boundary according to microbiostratigraphic and sedimentologic studies and also field work observation.
Stratigraphy and Palaeontology
Ghamarnaz Darabi; iraj Maghfouri Moghaddam; Abbas Sadeghi; Bizhan Yusefi
Abstract
In this study, biostratigraphy and Paleobathymetry of the Gurpi Formation in section southwest of Kuhdasht were studied. The thickness of Gurpi Formation in this section is 160 meters and its main lithology includes Marl, Limy Marl, Limestone and Shale. In this section Lower boundary of Gurpi Formation ...
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In this study, biostratigraphy and Paleobathymetry of the Gurpi Formation in section southwest of Kuhdasht were studied. The thickness of Gurpi Formation in this section is 160 meters and its main lithology includes Marl, Limy Marl, Limestone and Shale. In this section Lower boundary of Gurpi Formation is transition with Ilam Formation, and its upper boundary with Amiran Formation is unconformably. Here, on the basis of foraminiferal studies,50 species belonging to 24 genera of planktic foraminifera and Benthic were identified. Based on the stratigraphic distribution of the well known foraminifers, six foraminiferal biozones were established in the Gurpi Formation including: Globotruncana ventricosa Interval Zone, Radotruncana calcarata Taxon Range Zone, Globotruncanella havanensis Partial Range Zone, Globotruncana aegyptiaca Interval Zone, Gansserina gansseri Interval Zone, Contusotruncana contusa Interval Zone.The age of Gurpi Formation in this examined is determined based on identified biozones of Middel Campanian to Late Maastrichtian. A depth of 450 - 600 m was assigned for most parts of the sediments Gurpi Formatan was assigned ccording to planktic/epibenthic ratio and Percentage Morphotype 3 and the regression equation Depth = e (3.58718 + (0.03534 × %P*))
Stratigraphy and Palaeontology
A. Mahanipour; Reza Afrooz
Abstract
In the present study, calcareous nannofossil biostratigraphy was investigated at the Paleocene ‒ middle Eocene interval at northeast Kazerun (Shahneshin anticline). A thickness of 50 m from the upper part of Gurpi ‒ lower part of Pabdeh formations is investigated and mainly consists of marly limestone, ...
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In the present study, calcareous nannofossil biostratigraphy was investigated at the Paleocene ‒ middle Eocene interval at northeast Kazerun (Shahneshin anticline). A thickness of 50 m from the upper part of Gurpi ‒ lower part of Pabdeh formations is investigated and mainly consists of marly limestone, marly shale and marl. 180 species from 31 geneus of calcareous nannofossils are identified. According to the index calcareous nannofossils and based on Agnini et al. zonation, zone CNP3 to CNP11 and zone CNE1 to CNE8 are identified at the Paleocene and Eocene interval, respectively. These biozones corresponds with zone NP3 to NP9 (in Paleocene) and NP10 to NP14 (in Eocene), based on Martini zonation. Regarding calcareous nannofossil assemblages and biozones, the Paleocene ‒ Eocene boundary is located between CNP11/NP9 and CNE1/NP10 zones, where the top of Fasciculithus richardii group is recorded. The extinction of Fasciculithus is recorded at 23 m by the last occurrence of Fasciculithus tympaniformis, which is considered as an index for early Eocene. The appearance of some species, such as Rhomboaster spp., Tribrachiatus bramlettei and assymetrical species of Discoaster araneus is recorded at the Paleocene ‒ Eocene boundary similar to other parts of the world.
E. Zarei; E. Ghasemi-Nejad; A. Dehbozorgi
Abstract
The Gurpi Formation was studied from different aspects at two sections, Farhadabad and Kavar, in southwest and southeast of Ilam where it is composed of 205 m and 158 m of grey to blue marl and shale beds and occasionally thin beds of argillaceous limestones with two formal members of Seymareh (Lopha) ...
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The Gurpi Formation was studied from different aspects at two sections, Farhadabad and Kavar, in southwest and southeast of Ilam where it is composed of 205 m and 158 m of grey to blue marl and shale beds and occasionally thin beds of argillaceous limestones with two formal members of Seymareh (Lopha) and Emam-Hassan. In order to reconstruct paleoclimate during depositional course of the formation, paleontological and palynological data (ratio of specialist to generalist foraminifera (e.s/e.g) and warm-temperate waters dinocysts and spore and pollen grains) were used statistically. The results show that the Gurpi Formation is mainly deposited in a warm-humid climate with two sharp decreases happening in temperature in early Maastrichtian and Danian.
A Mahanipour; A Najafpour; M Dastanpour
Abstract
Calcareous nannofossils have been investigated at the lower part of the Gurpi Formation at the southwest of Gurpi anticline. According to the index calcareous nannofossils CC22/UC15eTP to CC24/UC18 bio-zones have been identified and the age of Late Campanian ‒ Early Maastrichtian is considered for ...
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Calcareous nannofossils have been investigated at the lower part of the Gurpi Formation at the southwest of Gurpi anticline. According to the index calcareous nannofossils CC22/UC15eTP to CC24/UC18 bio-zones have been identified and the age of Late Campanian ‒ Early Maastrichtian is considered for the studied interval. Statistical analysis of the assemblages indicate the presence of high and low nutrient taxa. The relative abundance of oligotrophic taxa (Watznaueria barnesae, Watznaueria fossacincta, Prediscosphaera spp., Eiffellithus spp., Lithraphidites carniolensis, Staurolithites spp., Micula staurophora, Cribrosphaerella ehrenbergii) is higher than eutrophic forms (Biscutum constans, Discorhabdus ignotus, Placozygus spiralis, Reinhardtites spp., Zeugrhabdotus spp., Tranolithus orionatus), and an increasing trend in the relative abundance of oligotrophic taxa along with a decreasing trend in the relative abundance of eutrophic forms can be observed towards the upper parts of the section (Campanian-Maastrichtian boundary and Early Maastrichtian).
L Fazli
Abstract
For biostratigraphy of the Gurpi Formation, three sections of Halegan well, Kuh-e-Harm and Kuh-e- Nareh were selected and sampled in south Qir, Fars province. The formation is 152m thick in Kuh-e- Harm section, 124m in Kuh-e Nareh section and 128 m in well Halegan and is mainly containing argillaceous ...
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For biostratigraphy of the Gurpi Formation, three sections of Halegan well, Kuh-e-Harm and Kuh-e- Nareh were selected and sampled in south Qir, Fars province. The formation is 152m thick in Kuh-e- Harm section, 124m in Kuh-e Nareh section and 128 m in well Halegan and is mainly containing argillaceous limestone with interbeds of limestone. In Kuh-e-Harm section and Halegan well the Gurpi Formation unconformably overlies the Ilam formation and underlies the Pabdeh Formation. In Kuh-e- Nareh, the Gurpi Formation conformably overlies Ilam Formation and unconformably underlies the Pabdeh Formation. A total of 108 samples were collected and studied from the three sections mentioned and 25 Species of planktonic foraminifera belonging to 10 genera and 3 species of benthic foraminifera were identified.
On the basis of the planktonic foraminifera the age of the Gurpi Formation was determined as Campanian to Maastrichtian in Kuh-e- Harm and Halegan well and Santonian to Maastrichtian in Kuh-e-Nareh. A few biozones differentiated here are comparable with global biozones of Caron 1985 and Wynd 1963. Based on the distribution of planktonic foraminifera 6 biozones are identified as follow:
Globotruncanita elevate Partial Range Zone .
Globotruncana ventricosa Interval Range Zone .
Radotruncana calcarata Total Range Zone .
Globotruncanella havanensis Partial Range Zone .
Globotruncana aegyptica Interval Range Zone .
Gansserina gansseri Interval Range Zone .
In Halegan well Globotruncana falsostuarti zone instead of Globotruncanella havanensis Zone and Globotruncana aegyptiaca biozone was erected by the author. This zonation can be correlated with Globotruncanita elevate Total Range Zone and Globotruncanita stuarti- pseudotextullaria varians Assemblage Zone of Wynd, 1963.
E Zarei; E Ghasemi-Nejad
Abstract
The Gurpi Formation at Farhadabad section in west of Darehshahr, was studied in detail for environmental changes and water–level fluctuations via using organic matter contents of the rock samples. Depositional environment interpretation was done based on integration of evidences derived from ...
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The Gurpi Formation at Farhadabad section in west of Darehshahr, was studied in detail for environmental changes and water–level fluctuations via using organic matter contents of the rock samples. Depositional environment interpretation was done based on integration of evidences derived from organic geochemistry analysis (TOC, TIC and Aliphatic n-alkane (short, mid and long chain n-alkane to sum of n-alkane, TAR (terrigenous-aquatic ratio), CPI(Carbon Preference Index), ratio of C17 to C27 and Isoperinoids (pr/ph,pr+ph/nC17+nC18, pr/nC17and ph/nC18) and palynofacies data (Amorphous organic matter, marine palynomorphs and palynomaceral). Statistical studies on palynomorphs confirm the results gained from the organic geochemical analysis. High ratio of palynomaceral and high TAR and CPI and dominance of long chain n- alkane and low ratio of C17/C27 (C17 relative to C27) and high ratio of Pr/Ph (>1) indicate regression condition at the base of the Gurpi Formation, Lopha Member, top of Emam-Hassan Member and Cretaceous – Tertiary boundary. On the other hand high abundance of marine palynomorphs and transparent amorphous organic matter and unimodal n-alkane with a marked even over odd predominance (CPI <1) and TAR <1 and high C17/C27 (C17 relative to C27) and low ratio of pr/nC17<0.5 indicate transgressive condition in upper part of Globotruncanita stuartiformis biozones, black shales between Lopha and Emam- Hassan, upper part of Contusotruncana contusa biozones and at the base of purple shale of the Pabdeh Formation. Maximum flooding surface probably equates the 70 Ma MFS K175, 68 Ma MFS K180 and 58 Ma MFS Pg10 of Sharland et al., 2001 that is recorded in many parts of the Arabian Plate. The relative sea level curve resulted in form this study is well in accord with the existing eustasy curves especially for the Campanian- Maastrichtian boundary indicating effect of eustasy on relative sea- level changes during this period. Combining all these data, an open marine environment with terrestrial organic input under suboxic to anoxic conditions can be concluded for the depositional course of the Gurpi Formation.
L Bakhshandeh1; KH Khosro Tehrani; T Mohtat; S.H Vaziri; F Keshani
Abstract
The Gurpi Formation is located in the Zagros basin, SW Iran . This Formation in the Banroushan section, SW Ilam,consists of 225 m shale with interbeds of marl that has two formal Members including Seymareh (Lopha) and Emam Hassan . These Members are made up of limestone. The lower and upper boundaries ...
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The Gurpi Formation is located in the Zagros basin, SW Iran . This Formation in the Banroushan section, SW Ilam,consists of 225 m shale with interbeds of marl that has two formal Members including Seymareh (Lopha) and Emam Hassan . These Members are made up of limestone. The lower and upper boundaries of this Formation are continuos with the Ilam and Pabdeh Formations. In the present investigation, 46 planktonic species of 13 genera have been identified. The Gurpi Formation is divided into 10 biozone on the basis of planktonic foraminifera which are cosmopolitan and consist of :biozone1-Globotruncanita elevata Partial Range Zone; Biozone2- Globotruncana ventricosa Interval Zone; Biozone3- Globotruncanita calcarata Interval Zone; Biozone4- Globotruncanella havanensis Partial Range Zone; Biozone5- Globotruncana aegyptiaca Interval Zone; Biozone6- Gansserina gansseri Interval Zone; Biozone7-Contusotruncana contusa Interval Zone; Biozone8- Abathomphalus mayaroensis Interval Zone; Biozone9-Parasubbotina pseudobulloides Interval Zone; Biozone 10- Globanomalina pseudomenardii Interval Zone Based on planktonic foraminifera the Gurpi Formation in the study area was deposited during the Early Campanian to Paleocene times.
S Rahimi; A Sadeghi; M.R Partoazar
Abstract
In this research, the biostratigraphy of the Gurpi Formation in Kuh-e-Sefid section in east of Ramhormoz is studied. The thickness of the Gurpi Formation is 190.5m and consists mainly of shale, argillaceous limestone and marl. The lower boundary with the Ilam Formation is comformable with sharp lithology ...
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In this research, the biostratigraphy of the Gurpi Formation in Kuh-e-Sefid section in east of Ramhormoz is studied. The thickness of the Gurpi Formation is 190.5m and consists mainly of shale, argillaceous limestone and marl. The lower boundary with the Ilam Formation is comformable with sharp lithology and upper boundary with the Pabdeh Formation is unconformable with a gap between Late Maastrichtian and Late Paleocene. In this study, 47 species belonging to 17 genera and 8 biozones of planktonic foraminifera were recognized. The biozones consist of Dicarinella asymetrica zone, Globotruncanita elevate zone, Globotruncana ventricosa zone, Radotruncana calcarata zone, Globotruncanella havanensis zone, Globotruncana aegyptiaca zone, Gansserina gansseri zone, and Racemiguembelina fructicosa zone. The age of the Gurpi Formation based on these biozones is Late Santonian to Late Maastrichtian in this section.
N Badri; A.L Kani
Abstract
The Gurpi Formation has a wide extent in the Zagros Sedimentary Basin.It has received considerable attention due to its unique stratigraphic position, chronostratigraphic importance, and floral and faunal diversity and abundance.In order to biostratigraphically classification and correlation of theGurpi ...
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The Gurpi Formation has a wide extent in the Zagros Sedimentary Basin.It has received considerable attention due to its unique stratigraphic position, chronostratigraphic importance, and floral and faunal diversity and abundance.In order to biostratigraphically classification and correlation of theGurpi Formation in Kuh-e-Gach andKuh-e Kurdeh sections (Lar region, Fars province), this study concentrated on the calcareous nannofloral content of sediments.From the prepared 300 microscopic slides, a total of 53 species from 30 genera belonging to 15 families were determined, described and photographed. The distribution of nannofloral assemblage of the Gurpi Formation in Kuh-e Kurdeh reveals presence of CC18 to CC24 zones indicating an Early Campanian to Early Maastrichtian age, while in Kuh-e Gach CC19 to CC24 zones with an age range of Early Campanian to Early Maastrichtian are present. Occurrence of various speciesof low latitude affinities points toward such positioning of depositional basin of the Gurpi Formation.
S.A Samaie; F Malekghasemi; V Simmonds
Abstract
The area is located in 25 Km southwest of kazerun city in the Zagros folded zone. The Phosphate beds have been deposited in the core of the Sarbalesh-Baznak anticline with NW-SE trend. Stratigraphically, the Gurpi, Pabdeh, Asmari, Gachsaran, and Bakhtiyari Formations are outcropped in this area. Petrographic ...
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The area is located in 25 Km southwest of kazerun city in the Zagros folded zone. The Phosphate beds have been deposited in the core of the Sarbalesh-Baznak anticline with NW-SE trend. Stratigraphically, the Gurpi, Pabdeh, Asmari, Gachsaran, and Bakhtiyari Formations are outcropped in this area. Petrographic studies show that phosphate-bearing layers are composed of calcite, phosphate, glauconite and iron oxide with packstone to wackestone texture. Microfossil studies proved the age of Oligocene for the phosphate layers. The XRF and XRD analyses demonstrated that the phosphate-bearing mineral is fluor-apatite (Ca (PO4)3F). Sedimentary phosphate in this area was formed under the high energetic environment condition, phosphate saturated waters, and in the boundary of oxidation – reduction zone.
M. Asgharian Rostami
Abstract
In order to study the Gurpi formation for biostratigraphical purposes the 310 meters thick section was sampled at Mish-khas Sectiona, Ilam province. The sequence is mainly made up of monotonous marl, limy marl and Limestone and contains two formal members of Lopha (with brachiopod, Echinoid and Bivalve) ...
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In order to study the Gurpi formation for biostratigraphical purposes the 310 meters thick section was sampled at Mish-khas Sectiona, Ilam province. The sequence is mainly made up of monotonous marl, limy marl and Limestone and contains two formal members of Lopha (with brachiopod, Echinoid and Bivalve) and Emam-Hasan. Lower boundary Gurpi formation is contineous with Ilam Formation.At boundary both formation, Gray marl Gurpi formation located on limestone and limy marl at Ilam formation and upper boundary is continus with Pabdeh Formation. Sixty seven species belonging to 26 genera were identified and fourteen biozones were differentiated. These are: 1.Globotruncanita elevata partial range zone, 2. Globotruncana ventricosa interval zone, 3.Radotruncana calcarata total range zone, 4. Globigerinelloides subcarinatus partial range zone, 5.Globotruncana aegyptiaca partial range zone, 6. Gansserina gansseri partial range zone, 7.Contusotruncana contusa partial range zone, 8. Pseudotextularia intermedia partial range zone, 9. Racemiguembelina fructicosa partial range zone, 10.Pseudoguembelina hariaensis partial range zone, 11. Pseudoguembelina palpebra partial range zone, 12. Praemurica uncinata interval zone, 13. Morozovella angulata- Globanomalina pseudomeandri interval zone, 14. Globanomalina pseudomenardi total range zone. According to the planktonic foraminifera the formation encompases Lower Campanian to late Paleocene (Thanetian). lack of Marginotruncanid and Dicarinella asymetrica showing lower campanian for bas of section.There is distinct hiatus in Cretaceous-Paleogene boundary based on paleontology and sedimentology evidence. Analysis of Planktonic and Benthic foraminifers' assemblage at this section with Cretaceous biostratigraphical provinces is indicating a close similarity with those of Tethyan provinces.
Mohammad Parandavar; A Mahanipur; S. A Aghanabati; S. A. Hoseini
Abstract
In this study the upper part of Gurpi Formation and the lower part of Pabdeh Formation have been investigated with regard to the calcareous nannofossils. The thinkness of the studied section is about 127 meter and it consists of Marls, gray-green shales and purple shales. 50 genus and 101 species ...
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In this study the upper part of Gurpi Formation and the lower part of Pabdeh Formation have been investigated with regard to the calcareous nannofossils. The thinkness of the studied section is about 127 meter and it consists of Marls, gray-green shales and purple shales. 50 genus and 101 species of calcareous nannofossils have been recognised in the studied section. According to the index genus and species in the studied interval, calcareous nannofossil biozones CC25-CC26 have been recognized at the cretaceous sediments and NP1-NP5 and NTp1-NTp9 biozones have been determined at the Paleocene sediments that NP1-Np4 and NTp1-NTp7A biozones are reported for the first time from the upper part of Gurpi Formation at the studied section. With regard to these biozones, the age of the upper part of Gurpi Formation in the studied section is late Maastrichtian- late Danian (late early Paleocene) and the age of Pabdeh Formation is started from early late Paleocene. According to the nannofossil data, the K/Pg boundary is continuous and is located at the upper part of Gurpi Formation. The K/Pg boundary is marked by a decrease in abundance of Cretaceous species, increase in the abundance of Thoracosphaera operculata and the appearance of the new-Paleocene taxa. In the Danian sediments the Cretaceous species are present along with Paleocene species continuously and with a good preservation that can be considered as surviving species that may have passed the boundary and are present at the Danian sediments.
S. Senemari; Sh. Hasanpour
Abstract
Calcareous Nannofossils are good tool for biostratigraphy, especially in the Late Cretaceous. With respect to this and due to the lack of any precise paleontological study, the calcareous nannofossils of Ilam and Gurpi Formations were investigated in the Southwestern Sarvestan. These Formations consists ...
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Calcareous Nannofossils are good tool for biostratigraphy, especially in the Late Cretaceous. With respect to this and due to the lack of any precise paleontological study, the calcareous nannofossils of Ilam and Gurpi Formations were investigated in the Southwestern Sarvestan. These Formations consists of marl, clay limestone and shale. In this study, for the first time, 14 families, 22 genera and 39 species of nannofossils were identified. Based on the information obtained on nannofossils, the section is aged at Late Coniacian-Early Santonian to Early Maastrichtian corresponding to CC14-CC24 zones (Sissingh, 1977).
M. R. Esmaeilbeig
Abstract
The study of planktonic foraminifera of the Gurpi Formation at Kuh-e Khane Kat (east of Shiraz) led me to find standard biozones from Early Santonian to Middle Campaninan. Four biozones were determined: biozones I (Dicarinella asymetrica zone) and II (Rosita fornicata zone) belong to Early and Late Santonian. ...
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The study of planktonic foraminifera of the Gurpi Formation at Kuh-e Khane Kat (east of Shiraz) led me to find standard biozones from Early Santonian to Middle Campaninan. Four biozones were determined: biozones I (Dicarinella asymetrica zone) and II (Rosita fornicata zone) belong to Early and Late Santonian. Biozones III (Globotruncanita stuartiformis zone) and IV (Globotruncana ventricosa zone) represent the Early and Middle Campaninan. Due to a decrease in water depth in Kuh-e Khane Kat, Globotruncanita calcarata zone and other Maastrichtian plagic biozones were not recognized. In this section, Gurpi Formation is 220.5 meters thick and contains shale and argillaceous limestone. Its underlying and overlying formations are Sarvak and Tarbur.
M. Azizi; S. Senemari
Abstract
Using calcareous nannofossils is a powerful way for biozonation in sub-stage level, especially in the Late Cretaceous and Cenozoic, because they are planktonic, cosmopolitan, abundant and have very short age. Considering lack of any precise paleontological studies about the Gurpi Formation in the NW ...
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Using calcareous nannofossils is a powerful way for biozonation in sub-stage level, especially in the Late Cretaceous and Cenozoic, because they are planktonic, cosmopolitan, abundant and have very short age. Considering lack of any precise paleontological studies about the Gurpi Formation in the NW of shiraz (Bavan), nannofossils chose to investigate. This Formation consists of shale, marl and limestone. In this study, 23 genera and 46 species of nannofossils were identified. According to the identified marker species, 14 biozones were diagnosed that classified as CC14-CC26 and NP1(Base of the Pabdeh Formation). According to these biozones, it has been suggested that this section is aged of the Gurpi Formation from Early Santonian to Danian. The existence of CC26-NP1 zonal marker species of the K/T boundary has been considered which indicates continuous sedimentation from the Late Cretaceous to Early Paleocene.
M. A. Sina; A. Aghanabati; A. L. Kani; A. R. Bahadori
Abstract
Calcareous nannofossils are suitable for biostratigarphical studies since they are abundant, planktonic, rapidly evolving and largely cosmopolitan, especially in the late Cretaceous. In this regards, 131 microscopic slides from shale and marl sediments of Gurpi formation of Poldokhtar section with thickness ...
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Calcareous nannofossils are suitable for biostratigarphical studies since they are abundant, planktonic, rapidly evolving and largely cosmopolitan, especially in the late Cretaceous. In this regards, 131 microscopic slides from shale and marl sediments of Gurpi formation of Poldokhtar section with thickness of 320 meters were collected. Out of this, 22 genera and 35 species were determined and their range chart is plotted. The distribution of nannofossil species indicates that there are 9 biozones in the study Poldokhtar section that can be separated, based on first occurrence (FO) of index species. They can be placed in CC18-CC26 of Sissingh (1977) time zones. On this basis, the age of sedimentation of this formation can be suggested to be from lower Companion to late Masstrichtian. In addition, presence of index species of low latitude in Poldokhtar section of Gurpi formation shows that this sedimentary basin was located in low latitude at the time of sedimentation.
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.
saeedeh senemari; L. Fazli; M. Omrani
Abstract
Nannofossils and foraminifera planktonic have been short range stratigraphy and spread vast geographical because of that two fossils groups can be used for subdividing biostratigraphy. According to this, and due to the lack of any correlational paleontological study, the nannofossils of Gurpi Formation ...
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Nannofossils and foraminifera planktonic have been short range stratigraphy and spread vast geographical because of that two fossils groups can be used for subdividing biostratigraphy. According to this, and due to the lack of any correlational paleontological study, the nannofossils of Gurpi Formation have been investigated in north of Gachsaran. This formation has been formed of marl. As a result of this study and based on the obtained nannofossils and foraminifera planktonic, the studied section is Late Santonian to Late Maastrichtian in age, that corresponding to CC16-CC26 Zones (Sissingh, 1977) and Dicarinella asymetrica- Globotruncanita elevata Zone toAbathomphalus mayaroensis Zone (James & wind, 1985).
M. Hosseini-Barzi; M. Houshyar; H. Ghalavand
Abstract
Field study, calcimetery and petrography of thin sections from Gurpi type section and petrography of cuttings from Ziloee oil field (well No. 5 and well No. 8) represent two carbonate members and two hybrid (mostly marl and in a few samples clay marl) members in these deposits. Microfacies analysis of ...
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Field study, calcimetery and petrography of thin sections from Gurpi type section and petrography of cuttings from Ziloee oil field (well No. 5 and well No. 8) represent two carbonate members and two hybrid (mostly marl and in a few samples clay marl) members in these deposits. Microfacies analysis of the carbonate members implies 2 microfacies belong to open sea of a carbonate ramp model. Moreover, authigenic glauconite and phosphate and framboidal pyrite propose deposition of these sediments in an anoxic condition. XRD and SEM analysis of marl members provide existence of illite and chlorite as clay minerals by certain detrital source and smectite by digenetic and probability detrial source in the upper marl member and existence of quartz in lower member. Coexistence of these minerals proposes a temperate climate during deposition of the upper marl member. Semi-quantitative analysis of XRD data represents descending trend for relative amounts of illite and ascending trend for smectite during deposition of upper marl member of Gurpi Formation which implies deepening of the sedimentary basin and relative climate warming. The digenetic processes in these deep marine deposits are limited to cementation, illitization, hematization and fracturing. Moreover, studying SEM images evident autogenetic origin of smectite in two samples from upper cretaceous (under K/T boundary) which can form during fluid exchange with mafic minerals and/or detrial clay minerals such as detrial smectite, illite. The absence of digenetic smectite in two samples from Paleocene (over K/T boundary) can be related to change in basin condition in Zagros basin, this period of time. Also, studying relative abundance of K and Th in NGS logs of well number 8 in Ziloee oil field shows that clay minerals in this formation are illite and montmorillonite.
