In this study, the Delichai Formation in the Reyabad stratigraphic section located northeast of Shahroud was selected to investigation of the Jurassic deposits of the Alborz sedimentary basin. Dalichai Formation in this section with 165 meter thickness, mainly consists of limestone with interbedded shale. Nannofossil studies led to identification of 32 species belong to 19 genera of calcareous nannofossils. Index nannofossil species indicate the NJ11 to lower boundary of NJ15b biozones of Bown et al’s (1988) biozonation. The first occurrence of Pseudoconus enigma indicates an upper Bajocene age for the lower and beginning of the formation. While the last occurrence of Lotharingius crucicentralis indicates an upper Oxfordian age for the upper layers of the formation. The first occurrence of Ansulasphaera helvetica, Stephanolithion bigotii bigotii, Stephanolithion bigotii maximum, and the last occurrence of Stephanolithion bigotii maximum and Pseudoconus enigma are among other recorded occurrences in the Delichai Formation in the Reyabad section. In general index calcareous nannofossils point to upper Bajocian - upper Oxfordian for Dalichai formation in the Reyabad section.
Notghi Moghaddam, M. and Senemari, S. (2026). Biostratigraphy of the Dalichai Formation based on calcareous nannofossils in Reyabad section (northeast Shahroud). New Findings in
Applied Geology, 20(39), -. doi: 10.22084/nfag.2026.30636.1662
MLA
Notghi Moghaddam, M. , and Senemari, S. . "Biostratigraphy of the Dalichai Formation based on calcareous nannofossils in Reyabad section (northeast Shahroud)", New Findings in
Applied Geology, 20, 39, 2026, -. doi: 10.22084/nfag.2026.30636.1662
HARVARD
Notghi Moghaddam, M., Senemari, S. (2026). 'Biostratigraphy of the Dalichai Formation based on calcareous nannofossils in Reyabad section (northeast Shahroud)', New Findings in
Applied Geology, 20(39), pp. -. doi: 10.22084/nfag.2026.30636.1662
CHICAGO
M. Notghi Moghaddam and S. Senemari, "Biostratigraphy of the Dalichai Formation based on calcareous nannofossils in Reyabad section (northeast Shahroud)," New Findings in
Applied Geology, 20 39 (2026): -, doi: 10.22084/nfag.2026.30636.1662
VANCOUVER
Notghi Moghaddam, M., Senemari, S. Biostratigraphy of the Dalichai Formation based on calcareous nannofossils in Reyabad section (northeast Shahroud). New Findings in
Applied Geology, 2026; 20(39): -. doi: 10.22084/nfag.2026.30636.1662
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