M Allameh; B Torabian
Abstract
Farrokhi Formation is a Cretaceous rock unit in Central Iran that lithologically contains lime, marl and marly lime accompanied by layers of fossiliferous limestones. This formation lays conformably over the Haft-Tuman Formation, while its upper boundary is disconformable with Chupanan Formation. In ...
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Farrokhi Formation is a Cretaceous rock unit in Central Iran that lithologically contains lime, marl and marly lime accompanied by layers of fossiliferous limestones. This formation lays conformably over the Haft-Tuman Formation, while its upper boundary is disconformable with Chupanan Formation. In this study, 23 rock samples from marl segment of the Farokhi Formation were prepared palynologically and their various palynological constituents were characterized and quantified by percent. Assessing the organic elements of formation demonstrated fair preservation of organic matters in marl segments and allowed determination of the sedimentation rate and oxygen content. Palynofacies investigation signifies that marl segment has been deposited in shallow to open marine environment with medium energy, and one palynofacies has been diagnosed for it. According to typical dinoflagellate cysts, a warm and rather shallow environment with medium energy and variable salinity is suggested for the period of sedimentation of the marl segment.
Sh. Nouri; E. Ghaseminejad; M. R. Majidifard
Abstract
The Sanganeh Formation is one of the Early Cretaceous rock units in the Koppeh- Dagh basin. This formation in the Dahaneh Gholaman section (in north of Bojnord city) with a thickness of 900 meters (consist of marl, shale and limestone) is laying conformably on the Sarcheshmeh Formation and covered by ...
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The Sanganeh Formation is one of the Early Cretaceous rock units in the Koppeh- Dagh basin. This formation in the Dahaneh Gholaman section (in north of Bojnord city) with a thickness of 900 meters (consist of marl, shale and limestone) is laying conformably on the Sarcheshmeh Formation and covered by Atamir Formation. In this study, biostratigraphic investigations on 50 palynological samples from the Sanganeh Formation led to recognition of 21 genera and 31 species of dinoflagellate cysts indicating an age of Late Aptian-Albian belonging to Odontochitina operculata zone. Also palynofacies studies revealed two types of palynofacies (II and IV). Palynofacies studies show dominance of palynofacies II through the stratigraphic column indicating a marginal dysoxic-anoxic basin. On the other hand, presence of palynofacies IV in some parts along the stratigraphic column reflects increase in the depth of the marine environment from time to time.
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.
M Allameh; Z Sardar
Abstract
Aitamir Formation is one of the formations in sedimentary basins of Koppeh-Dagh in the north east of Iran. This formation has been made of a sandstone part in the lower and a shale part in the upper. Both the part are Glauconitic and often seen in Olive-green color. This research is on a section of a ...
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Aitamir Formation is one of the formations in sedimentary basins of Koppeh-Dagh in the north east of Iran. This formation has been made of a sandstone part in the lower and a shale part in the upper. Both the part are Glauconitic and often seen in Olive-green color. This research is on a section of a Aitamir formation based on Palynomorphs which has been conducted on the route from Mashhad to Kalat-e-Naderi, isn the edge of Zavin village with the thickness of 506 meters and the coordinates 36°43̒45.42" north latitude, and 59°57̒5.56"east longitude. 40 samples of this section have been gathered and 120 Palynological slides have been prepared. The study of these slides has resulted in the identification of 28 genera and 47 species of Dinoflagellates. Regarding the identified Dinoflagellates, the age of Aitamir formation in the mentioned Albian-Cenomanian section was determined. The study of the factors involved in preservation of organic materials shows the low to moderate levels of oxygen conditions, with low deposition and an inner to the outer Neritic environment for an Aitamir formation in the mentioned section. Based on the studies that have been done, three Palynofacies were identified for the Aitamir formation in Zavin section.