TITLE:
Barremian-Aptian Biostratigraphy in Yazd Block, Central Iran
AUTHORS:
Reza Hanifzadah, Koorosh Rashidi, Mahnaz Amir Shahkarami
KEYWORDS:
Lower Cretaceous, Limestone, Calcareous Algae, Orbitolinidae Family, Biostratigraphy, Shahkuh Formation, Taft Formation
JOURNAL NAME:
Open Journal of Geology,
Vol.5 No.6,
June
18,
2015
ABSTRACT: The Lower Cretaceous benthic Limestone in Yazd Block (Central Iran
zone) is known as the Taft and Shahkuh Formations. In this study, the age of
the Taft and Shahkuh Formation, is examined based on biostratigraphic and
paleontological investigations of Taft Formation in sections of Herisht (NE
Ardakan) and Abanbar (NE Ardakan) and Shahkuh Formation in Chahpalang section
(North Ardakan). According to the lithostratigraphic investigations, the taft
and Shahkuh Formation in these sections include of thin bedded to medium bedded
and massive limestone. Micropaleontology study of the Taft and Shahkuh
Formation has led to the recognition of numerous genus and species which belong
to Orbitolinidae Families such as: Dictyoconus pachymarginalis,
Montseciellaarabica, Mesorbitolina parva, Paleodictyoconus sp.,
Paleodictyoconusactinostoma, Palorbitolina sp., Palorbitolina lenticularis,
Praeorbitolinacormyi, Praeorbitolina cf. wienandsi, Praeorbitolina claveli,
Praeorbotolinasp., cf. Paleodictyoconus sp., Palorbitolina ultima. and
Calcareous Algae such as: Acroporella sp., Acroporella cf. Radoicicae,
Actinoporella sp., Arabicodiumsp., Arabicodium cf. elongates, Augioporella cf.
fouryae, Bacinellairregularis, Bueina sp., Boueina cf. hochstetteri, Boueina
minima, Bueina cf.pygmaea, Cayeuxia sp., Cayeuxia anae, Garwoodia sp.,
Garwoodia cf. maxima,Girvanella sp., Griphoporella aff. Cretacea, Halimeda sp.,
Kopedagaria sp.,Kopedagaria sphaerica, Lithocodium aggregatum, Marinella sp.,
Montiellaelitzae, Marinella lugeoni, Marinella cf. yogoslavica, Neomeris sp.,
Neomeriscf. cretacea, Neomeris cf. pfenderae, Parachaetetes asvapatii,
Permocalculussp., Permocalculus dragastani, Permocalculus minutes,
Pseudoactinoporella sp.,Pseudoactinoporella iranica, Pseudoactinoporella cf.
iranica, Pycnoporidiumlobatum, Rivularia sp., Salpingoporella sp.,
Salpingoporella cf. patruliusi,Salpingoporella cf. johnsoni, Salpingoporella
pygmaea, Salpingoporellamehlbergii, Salpingoporella aff. Turgida,
Salpingoporella cf. dinarica,Suppiluliumaella cf. praebalkanica, Udotea
flabellum. Based on the identified Microfossil, such as Orbitolinid fossil, the
age of the Taft Formation in the Kuh-e Herisht is assigned to Upper
Barremian-Middle Aptian, and in the Abanbar area is determined as Upper
Barremian-Lower Aptian, at least the age of the Shahkuh Formation in the
Chahpalang area is determined as Upper Barremian-Lower Aptian.