Biostratigraphic framework of the Judea Group of Israel (Jerusalem, Negev and Carmel areas): A calcareous nannofossil approach.

The Late Albian–Turonian Judea Group represents a significant sequence of shallow-water carbonates deposited across the Israel-Sinai sub-plate. While the biostratigraphy of the Judea Gr. has been extensively studied using ammonites, ostracods and foraminifera, calcareous nannofossil data remain sparse. This study documents the taxonomic composition and stratigraphic distribution of calcareous nannofossils in the Jerusalem and Northern Negev areas, providing a crucial comparative analysis with the high-diversity assemblages of the Carmel area.

To establish this biostratigraphic framework, 281 samples were examined from eight surface sections in the Judea Mountains and three boreholes in the Northern Negev (Kohal 1, Massada 1 and Zohar 1).

Species richness varies significantly from impoverished assemblages in the Jerusalem area (only Moza and Kefar Shaul Fms) (29–60 species) and Negev (33–39), to highly diverse complexes in the Carmel area (95–113).

In the Judea Mts, extremely rare nannofossils in the Kefira Fm. indicate the Upper Albian–Maastrichtian age, the benthic foraminifera indicate the Albian–Cenomanian age, and the presence of Hemicyclammina points to the Middle Cenomanian. In the Soreq Fm., rare nannofossils indicate the Albian–Maastrichtian age and benthic foraminifera specify the Cenomanian age. The Beit Me'ir Fm. is devoid of nannofossils, while benthic foraminifera indicate the Cenomanian age. Diverse nannofossils of the Moza Fm. indicate the Early–early Middle Cenomanian age (Zones UC1–UC2), whereas abundant benthic and scarce planktonic foraminifera point to the Cenomanian age. The Kefar Shaul Fm. is Late Cenomanian based on rich nannofossils (Subzone UC3d, undivided UC3e–Zone UC4 and Subzone UC5a). Rare planktonic foraminifera and ostracods specify the Late Albian–Cenomanian and Late Cenomanian ages, respectively. Rare nannofossils of the Bina Fm. broadly indicate the Upper Albian–Maastrichtian age, and benthic foraminifera point to the Late Cenomanian–Turonian age.

In the Northern Negev Hazera Fm., the nannofossils and ostracods identify the Hevyon Member as Early Cenomanian (Massada 1: nannofossil Zones UC1 and UC2, ostracod Zone UC-1) or Late Albian–Early Cenomanian (Zohar 1 nannofossil undivided Zones UC0–UC1 and Zone UC2; Kohal 1 nannofossil (Sub)Zones: UC0a–b, UC0c–UC1, UC2a, UC2b–c). Nannofossils from the 'En Yorqe'am Member specify the Early–Late Cenomanian age (Zone UC2, undivided Zones UC3–UC4) and the ostracods suggest the Late Cenomanian age (Zone UC-3) in the Massada 1 and Kohal 1 boreholes. The Zafit Member is Middle–Late Cenomanian in all boreholes (nannofossil undivided UC3–UC4 Zones, Subzone UC5a). The Avnon Member is Late Cenomanian (nannofossil Subzones UC5a and UC5b) in Kohal 1.

In the Carmel area, both boreholes yielded rich nannofossil assemblages supporting the Isfiye Fm. as Late Albian, and the Arqan Fm. as Late Albian–Middle Cenomanian (Zones UC0–UC3; foraminiferal zones P. appenninica, Th. globotruncanoides, Th. reicheli and R. cushmani). The Tavasim Volcanics is Late Albian (borehole CT2) or Late Albian–Lower Cenomanian (borehole CT8).

By integrating novel nannofossil data with existing macro- and microfossil zonations, this research establishes a robust framework for correlating lithologically diverse formations of the Judea Gr., filling a significant gap in the regional micropaleontological biostratigraphy.