Eocene to Oligocene nannofossils stratigraphy and environmental conditions in Izeh Province, Zagros Basin, East Tethys  

作　　者：Saeedeh Senemari Farah Jalili 

机构地区：[1]Department of Mining,Faculty of Engineering,Imam Khomeini International University,Qazvin,Iran [2]Department of Geology,Faculty of Science,University of Birjand,Birjand,Iran.

出　　处：《Journal of Palaeogeography》2021年第2期209-221,共13页古地理学报（英文版）

基　　金：supported by Grant 751541 of the Imam Khomeini International University。

摘　　要：Data obtained from the calcareous nannofossils, distributed in the upper part of the Pabdeh Formation(Priabonian–Rupelian) and the lower part of the Asmari Formation(Chattian) in the Bid-Zard section, were used to investigate the Eocene to Oligocene palaeoenvironmental conditions in the southwest of Izeh, southwestern Iran(eastern Tethys). The upper part of the Pabdeh Formation was composed of shale, thin-bedded pelagic limestone and dolostone, which is disconformably overlain by the Asmari Formation. For the first time, 29 species of calcareous nannofossils belonging to 13 genera were identified in the studied section. The calcareous nannofossils in the upper part of the Pabdeh Formation indicate the Isthmolithus recurvus Zone/Sphenolithus pseudoradians Zone(combined zone), Ericsonia subdisticha Zone, Helicosphaera reticulata Zone and Sphenolithus praedistentus Zone,from the Priabonian to the Rupelian. The Sphenolithus ciperoensis Zone of the Chattian was identified in the lower part of the Asmari Formation. Calcareous nannofossil stratigraphy across the upper Eocene–Oligocene interval also reveals a disconformity at the Rupelian/Chattian transition due to a bio-event. Shallowing of the basin and environmental changes in this part of the Tethyan domain could have led to the lithostratigraphic and biostratigraphic changes. In fact, during the late Eocene to late Oligocene, marine phytoplankton was sensitive to climate changes such as decreasing temperature, as well as possibly to a nutrient increase and changes in basin depth.

关 键 词：BIOSTRATIGRAPHY Calcareous nannofossils Ecological indicators Tethys domain ZAGROS PALEOGENE 

分 类 号：Q911.2[天文地球—古生物学与地层学]