نشریه دیرینه شناسی
سال دوم شماره 2 (پیاپی 4، پاییز و زمستان 1393)

A detailed study of the Lower Cretaceous Dasyclad algae of the Shahkuh Formation was done in the Chahpalang stratigraphic section (its name comes from the mountain in studied area). According to the study of the 101 thin sections, for the first time, we recognized 7 genus and 8 species of dasyclad algae from Shah Kuh Formation in Chah Palang section including Angioporella cf. fouryae, Griphoporella aff. cretacea, Kopetdagaria sphaerica, Montiella? elitzae, Neomeris sp., Pseudoactinoporella? iranica, Salpingoporella sp., Salpingoporella aff. Muehlbergi and Salpingoporella cf. pygmaea. Based on identified dasyclad algae, and the age of index Orbitolinid fossil that have been recognized in this formation, such as Dictyoconus pachymarginalis, Montseciella arabica, Praeorbitolina sp., Palorbirolina sp., the age of Shahkuh Formation is Barremian to Aptian.

For study of different types of stromatolites, their modes of growth and their relation to sequence stratigraphy within the Derinjal Formation, three stratigraphic sections at Dahuieh, Gatkueih and Gazueih in SE and E of Zarand (NW Kerman), were measured and sampled with thickness of 160, 140 and 130 meter, respectively. Modes of sediment accretion, trapping and binding of sedimentary grains, together with the morphology of stromatolites and microbial mats in the Late Cambrian are analyzed, in order to show the interaction between the growth patterns, morphology and facies association. Based on morphologic study and modes of growth, 4 main groups of stromatolity including stratiform stromatolite, single and lateral accretion, domed stromatolites, Columnar stromatolites and Coniform stromatolites were identified. Growth environmental analysis shows that these sediments have been deposited in tidal environment. Relation between sea level changes and stromatolite types show that stratiform stromatolite is consistent with early TST and late HST, and domed, columnar and coniform stromatolies have been observed in late TST and early HST.

Study of plant macrofossils of Jurassic sediments of Shemshak Group in Eshkevarat-e-Olia areas led to identification of two species consisting Lobifolia rotundifolia from Ferns Group (Division Pteridophyta & Filicales Order) and Ptilophyllum vasekgahense from Gymnospermae Group (Division Cycadophyta & order Bennettitales) that had been reported from Rhaetian (Late Triassic) and Dogger (Middle Jurassic) and in this investigation, they are reported from Late Liassic (Toarcian) for the first time. Also the species of Nilssonia herriesi from Cycadophyta Division and order Cycadales are reported for the first time from Alborz Structural – Facies Region. Base on stratigraphical distribution of accompanied macrofossils species such as Klukia exilis, Klukia westii, Coniopteris hymenophylloides, Todites williamsoni, Cladophlebis aktashensis, Pseudoctenis herriesi, Nilssonia macrophylla, Nilssonia tenuinervis, Ptilophyllum cutchense, Ptilophyllum sahnii, Ptilophyllum sakrigaliensis and Elitides thomasi, the age of the Shemshak Formatio in the Eshkevarat-e-Olia is assigned to be Toarcian - Bajocian (Late Liassic–Early Dogger).

Large benthic foraminifera and dasycladalean green algae are the most common and important (micro) fossils in Lower Cretaceous shallow-water sediments of the Tethyan Realm. In this paper, we introduced such taxa and their importance in age dating of Lower Cretaceous strata in the Kopet-Dagh sedimentary basin. Also, according to determinations of index taxa (fauna and flora) in this period, the biostratigraphic boundary of Late Barremian-Early Aptian can be defined in the west Kopet-Dagh sedimentary basin for the first time. In addition, according to the FO and LO of the index taxa, 5 biozones are determined in the studied section which show Late Barremian-Early Aptian age for the studied stratigraphic sections.

Biostratigraphy of Bahram Formation succession, with 359.8 meter thickness, in the Sardar section (North of Kerman, Central Iran) is done in this study. Bahram Formation is mostly composed of limestones (with a lesser amount of sandstones), and conformably overlies the top sandstone beds of the Padeha Formation. But, the upper boundary with the Hutk Formation (Late Tounaisian) is disconformable. Conodont fauna, consisting of thirty-nine species and subspecies, are indicatives of late Givetian to middle Famennian age. Biofacies analysis proves the shallow marine environments for this section similar to many other successions in the Central Iran and adjacent areas (such as Himalaya and Pamir).

Julfa Beds at Zal section, northwest Iran, with 33 meter thickness, are composed of gray, cream to red limestones, nodular in some parts with intercalations of green, gray to red shales. They are very important because they are very rich in the Late Permian brachiopod. This research, which is focused on the mentioned fauna from the Zal section, is led to identification of 38 species of 21 genera belong to orders: Athyridida, Orthotetida, Orthida, Productida, Rhynchonellida, Spiriferida and Terebratulida. Three taxon range zone, including Araxilevis intermedius Zone, Permophricodothyris ovata Zone and Transcaucasathyris araxensis Zone and one Permophricodothyris ovata - Transcaucasathyris araxensis Interval Zone are defined in this section. The mentioned biozones and their comparison with the same sequences in Iran, Transcaucasica and South China confirm the age of Wuchiapingian (Dzhulfian) for this succession.

In order to study the Stratigraphic of sedimentary deposits of the Cenomanian in Kopeh Dagh, the Taghiabad section was selected. In the eastern Kopeh Dagh, the upper part of Aitamir Formation has this time range characteristic. The upper part of this formation includes shale and glauconitic sandstones and contains variety of ammonite fauna. Ten genera and species of ammonites are found inside these sedimentary layers and are identified as Acanthoceras rhotomagense, Cunningtoniceras cunningtoni, Schloenbachia varians, Schloenbachia coupei, Hypoturrilites sp., Mantelliceras saxbii, Mantelliceras mantelli, Hyphoplites curvatus arausionensis, Placenticeras mediasiaticum and Placenticeras gaurdakense. These ammonites belong to 5 families of ammonites including Hoplitidae, Turrilitidae, Schloenbachiidae, Acanthoceratidae and Placenticeratidae. These ammonites represent the Early to Middle Cenomanian age and are of a Boreal environment.

A detailed study of the Lower Cretaceous Dasyclad algae of the Shahkuh Formation was done in the Chahpalang stratigraphic section (its name comes from the mountain in studied area). According to the study of the 101 thin sections, for the first time, we recognized 7 genus and 8 species of dasyclad algae from Shah Kuh Formation in Chah Palang section including Angioporella cf. fouryae, Griphoporella aff. cretacea, Kopetdagaria sphaerica, Montiella? elitzae, Neomeris sp., Pseudoactinoporella? iranica, Salpingoporella sp., Salpingoporella aff. Muehlbergi and Salpingoporella cf. pygmaea. Based on identified dasyclad algae, and the age of index Orbitolinid fossil that have been recognized in this formation, such as Dictyoconus pachymarginalis, Montseciella arabica, Praeorbitolina sp., Palorbirolina sp., the age of Shahkuh Formation is Barremian to Aptian.