Sedimentology
Somayeh Parham; Alireza Piryaei; Mansur Ghorbani; Seyyed Reza Moosavi Harami
Abstract
Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate ...
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Late Cretaceous in Zagros encompasses regional tectonics and caused foreland basin to form in northeast of the Arabian Plate. Salt tectonics is also locally affected this area. One of the time periods that can better picture this tectono-sedimentary evolution is Maastrichtian. In order to investigate this evolution in the Maastrichtian time, a regional cross-section was made inthe Fars outcrops and wells. A sedimentological study and sequence stratigraphy have been accomplished along this transect. Maastrichtian deposits consist of the upper part of the Gurpi and the Tarbur formations in the studied transect. Based onsedimentological investigation, 14microfacies have been identified. This microfacies were deposited in 4microfacies belt including tidal flat, restricted and open lagoon, reef and open marine in a shelf carbonate platform. Based on sequence stratigraphic studies, 3 sedimentary sequences were identified in the studied interval. Correlation along the transect revealed that the Maastrichtian deposits occurred on the forebulge of Zagros foreland basin. It is also concluded that the fore-buldge shows a nearly smooth topography and thus accommodation space is homogeneous. Hence the thickness of the Maastrichtian deposits does not vary so much along this transect. Thickness anomaly in Namak-dehkuyeh occurs as a result of salt structure which decreased accommodation space.
M Khanjani; S.R Moussavi-Harami; H Rahimpour-Bonab; M.R Kamali; A Chehrazi
Abstract
The Santonian – CampanianIlam Formation is one of the major reservoirs of Bangestan Group in the Zagros petroliferous basin. In the Siri Alvand Oilfield located in the Persian Gulf this formation with a total thickness of 130 m, consists of limestone. In this study, microfacies, depositional environments, ...
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The Santonian – CampanianIlam Formation is one of the major reservoirs of Bangestan Group in the Zagros petroliferous basin. In the Siri Alvand Oilfield located in the Persian Gulf this formation with a total thickness of 130 m, consists of limestone. In this study, microfacies, depositional environments, diagenetic processes and sequence stratigraphy of the Ilam Formaton in Siri Alvand oilfield was studied. Based on thin sections studies, 8 microfacies and 4 facies associations were identified that deposited in a homoclinal carbonate ramp environment. On the basis of petrographic studies, the main diagenetic processes affected these rocks include bioturbation, cementation, dissolution, dolomitization, stylolitization, pyritization and fracturing. The most important cement types in this formation are bladed calcite, fine equant calcite, drusy mosaic calcite, coarse blocky calcite and syntaxial calcite overgrowth. Sequence stratigraphic studies led to recognition of four third order depositional sequences in the Ilam Formation that all of them terminated to the type 1 sequence boundary. Finally, facies and diagenetic processes intensity were studied in each sequence.
S.Z Pourheidar; A Mahboubi; M.H Mahmudy Gharaie; S.R Moussavi Harami
Abstract
The Mozduran Formation in west of the Kopet-Dagh basin, NE Jajarm, is mainly composed of dolostone in top and base, and mudstone to grainstone limestones in the middle parts of Cheshme-Khan section. This formation in the Qezel-Tapeh2 well is composed of alternative limestone and shale layers. Based on ...
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The Mozduran Formation in west of the Kopet-Dagh basin, NE Jajarm, is mainly composed of dolostone in top and base, and mudstone to grainstone limestones in the middle parts of Cheshme-Khan section. This formation in the Qezel-Tapeh2 well is composed of alternative limestone and shale layers. Based on the facies studies, four carbonate facies associations (open marine, barrier, lagoon and tidal flat) have been identified, including fifteen carbonate microfacies and two siliciclastic lithofacies. It is interpreted that the Mozduran Formation in this area were deposited in a homoclinal ramp of a carbonate platform. The sequence stratigraphy analysis led to distinguish five depositional sequences in the Cheshme-Khan section and four depositional sequences in the Qezel-Tapeh2 well. The lower boundary of the 1st sequence (paleosol layar in the Cheshme-Khan section) and the upper boundary of the latest sequence (continental deposits) of both sections are a "type 1" sequence boundaries, but other boundaries are interpreted to be a "type 2" sequence boundaries. The relative sea-level curve of the study area comparing to the global sea-level curve, shows a relatively correlation and some differences can probably be related to regional tectonic setting of the Kopet-Dagh basin due to subsidence along the longitudinal faults and sediment loading.
D Dehnavi; S.R Moussavi-Harami; M.H Mahmudy Gharaie; F Ghaemi; F Ghaemi
Abstract
For understanding parent rocks, tectonics setting, paleoweathering condition and classification of Binalood’s Oligocene deposits, the petrography analysis was done, on samples from Damanjan and Baghshan-Gach sections, north of Neyshabour. 14 sandstones and 6 shale samples from both sections were ...
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For understanding parent rocks, tectonics setting, paleoweathering condition and classification of Binalood’s Oligocene deposits, the petrography analysis was done, on samples from Damanjan and Baghshan-Gach sections, north of Neyshabour. 14 sandstones and 6 shale samples from both sections were analyzed for major elements. Petrographic studies and geochemical data show that these sandstones are Litharenite to lithic arkose and have been deposited in tectonics setting including active continental margin for Damanjan section and continental island arc for Baghshan-Gach section with felsic to intermediate source. Based on elemental analysis, paleoweathering condition was relatively weak at the time of deposition in both sections; however, paleoweathering was stronger in Damanjan than Baghshan –Ghch sections. Also, using petrographic and elemental data, it can be concluded that the paleoclimate was semi-humid to semi-arid at the time of deposition.
A. Karimian Torghabeh; S.R Moussavi-Harami; A. Mahboubi
Abstract
Siliciclastic succession of Pesteliegh Formation, Lower Paleocene, has an extensive exposure in the Kopet Dagh basin. Three stratigraphic sections, consist of Dareh Gaz, Shamsikhan and Karnaveh in central Kopet Dagh, were measured and studied for environmental interpretation and sequence stratigraphic ...
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Siliciclastic succession of Pesteliegh Formation, Lower Paleocene, has an extensive exposure in the Kopet Dagh basin. Three stratigraphic sections, consist of Dareh Gaz, Shamsikhan and Karnaveh in central Kopet Dagh, were measured and studied for environmental interpretation and sequence stratigraphic analysis. This study led to identification of 8 lithofacies (Gcm, Gmg, Gt, Sm, Sh, Sp, St و Fm) and 5 architectural elements ( OF, CH, SB,GB,SG). Based on this data, siliciclastic sediments of Pesteliegh Formation were deposited in both fine-grain meandering and braided river systems. Sequence stratigraphy analysis show that siliciclastic sediments of the Pesteliegh Formation deposits is composed of two depositional sequences that were effected by tectonic and base level changes during the sea level fall. Both depositional sequences consist of LE and TE phases. Paleogeographic reconsruction of the Early Paleocene time show that these deposits were formed during 4 different stages in relation to changes in accommodation space.
S. R. Moussavi-Harami; Y. Nasiri; A. Mahboubi; A. Bayetgoll
Abstract
Amiran Formation (Paleocene) in Lorestan, folded Zagros zone, contains a diverse and exceptionally well preserved ichnofauna. A quantitative study of trace fossil in the Paleocene deep-marine clastic systems, this Formation, shows that they are powerful discriminators of submarine fan and related environments. ...
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Amiran Formation (Paleocene) in Lorestan, folded Zagros zone, contains a diverse and exceptionally well preserved ichnofauna. A quantitative study of trace fossil in the Paleocene deep-marine clastic systems, this Formation, shows that they are powerful discriminators of submarine fan and related environments. The host lithologies are conglomerates, sandstones, siltstones and mudstones. These sediments are interpreted to be deposits in upper to lower-fan palaeoenvironment. Channel deposits consist of thick-bedd turbidite and interchannel deposits are interpreted to be deposited by unconfined debris flows and high concentration turbidity currents. The ichnofauna with high diversity is most frequently, and best, preserved within the Tcde interval of turbidities, which are interpreted as interchannel deposits, produced by low concentration turbidity flows. On the basis of trace fossil diversity, ichnotaxonomic composition, ethology, and morphologic complexity, trace fossils assemblage were grouped into pre-depositional or post-depositional forms. The predepositional assemblage is rich in graphoglyptids and grazing trails, and feeding structures. The ichnodiversity, ethology, and morphologic complexity of the predepositional association are indicative of the Nereites ichnofacies. The postdepositional association essentially consists of dwelling and feeding traces. The post-depositional association includes elements of the Skolithos ichnofacies. Overall characteristics of trace fossils suggest that from the proximal to the distal environment of Amiran Formation, proportions of domichnia trace-fossil assemblages decreases while agrichnia, fodinichnia and pascichnia increases.
