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) ...
Read More
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.
M. Asgharian Rostami; E. Ghasemi-Nejad; M. Shafiee Ardestani
Abstract
At this research are studied late cretaceous sediments at Ziarat-kola section, Central Alborz, in order to Palaeobathymetry and sea level change. These sediments are with about 200m thickness consist of monotonous Marl and limy marl. Based on Planktonic foraminifera gain Upper Maastrichtian stage (Abathomphalus ...
Read More
At this research are studied late cretaceous sediments at Ziarat-kola section, Central Alborz, in order to Palaeobathymetry and sea level change. These sediments are with about 200m thickness consist of monotonous Marl and limy marl. Based on Planktonic foraminifera gain Upper Maastrichtian stage (Abathomphalus mayaroensis zone). In order toPalaeobathymetry and sea level change used to three methods common consisting of morphotype Planktonic foraminifera, ratio Planktonic foraminifera to benthic foraminifera and assigning genus and benthic foraminifera species. With morphotype analysis was indicated that third morphotype which are more deep index increase at the initial part and first morphotype that are shallow index increasing at middle section. In this manner, depth change was examinated to use two genus, Globotruncana (deep dweller) and Pseudoguembelina (Mixed layer dweller). In orther to assign paleodepth at this area used to Planktonic foraminifera to total foraminifera minus infaunal Benthic foraminifera and the regression equation [Depth = e (3. 58718 + (0. 03534 × %*p)].examination genus and Benthic foraminifera species depth index and such results gain at above method were indicating that this sediments in upper bathyal and middle bathyal. Thus, results indicate that beginning and end of are deeper from middle section.
M. Asgharian rostami; E. Ghasemi-Nejad; M. Shafiee ardestani; B. Balmaki
Abstract
In order to studying salinity and biostratigraphy in Central Alborz basin, two sections Jorband and Ziarat-kola are sampled and studied Planktonic foraminifera and Echinoids fossil. Studying of foraminifera In Ziarat-Kola section determining three biozone by planktonic foraminifera. 1: Racemiguembelina ...
Read More
In order to studying salinity and biostratigraphy in Central Alborz basin, two sections Jorband and Ziarat-kola are sampled and studied Planktonic foraminifera and Echinoids fossil. Studying of foraminifera In Ziarat-Kola section determining three biozone by planktonic foraminifera. 1: Racemiguembelina fructicosa Interval zone 2:Pseudoguembelina hariaensis Interval zone 3: Pseudoguembelina palpebra Interval zone.that showing late maastrichtian. As well, at Jorband section assigning three biozone by Planktonic foraminifera 1: Contusotruncana contusa Interval zone, 2: Planoglobulina brazoensis Partial range zone, 3- Racemiguembelina fructicosa Interval zone. That showing maastrichtian. Likewise, in order to determining Paleosalinity select two sections at Jorband and Ziarat-Kola. Main object assigning Paleosalinity confirm sensitive Rugoglobigerina to changes of salinity. At former section used from excessive changes of Echinocorys and in later one used from ratio of kinds Foraminifera tests (Porcelaneous, Agglutinate and Hyaline). In middle parts of Ziarat-Kola section, percentage of porcelaneous tests was more than basal and upper ones. In middle parts of Jorband section salinity was less than basal and upper ones that examined by abundancy of the genus of Echinocorys. Physiological changes of body in this echinoderm also justify salinity changes throughout Jorband section. According to Whitenella is ancestor of Rugoglobigerina and also sensitive to salinity, it is possible that Rugoglobigerina show characteristic of its ancestor that justify by studying of salinity changes in two section of Central Alborz.
