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Stable carbon and oxygen isotopes of benthic and planktonic foraminifera as palaeoenvironmental and palaeoclimatic proxies for the Bartonian–Priabonian in northwestern Saudi Arabia

Allam Sherif, Korin Asmaa, Herlambang Adhipa, Humphrey John D., Alnajjar Mohammed I., Bahameem Ahmed A., Memesh Abdullah M., Zalmout Iyad S., Kaminski Michael A.

Geological Quarterly

2025

Vol. 69, No. 3

art., no. 26

The Eocene epoch is known for its fluctuations in climate patterns and the dominance of global greenhouse climate. The Rashrashiyah Formation represents the middle to upper Eocene (biozones E13–E14) marine deposits of claystone to limestone in Saudi Arabia and contains well- to poorly-preserved planktonic and benthic foraminifera. Four different genera were selected for isotopic analysis (Acarinina spp., Subbotina spp., Cibicidoides spp., and Uvigerina spp.). Foraminiferal calcite was used to define the depth of habitat for each genus and mode of life. Four equations were used to infer palaeotemperatures from foraminiferal calcite; three equations are applicable for estimation of sea-surface temperatures (SST) from planktonic foraminifera data, while the fourth equation is applicable estimation of bottom-water temperatures using benthic foraminifera data. The mean SST derived from Acarinina spp. is ~38°C, while the mean bottom water temperature based on Uvigerina spp. is 26°C. Palaeotemperatures derived from this study are notably higher than those reported from this area in the existing literature. This discrepancy may be due to the unique palaeoclimatic and palaeogeographic conditions prevalent in the study area. The stable isotope curve is used to infer the transition between the Bartonian and Priabonian and the general cooling trend during this period.

A systematic review of Paleogene agglutinated foraminifera with internal structures (subfamily Pavonitininae) from the Eocene of northwestern Saudi Arabia

Korin Asmaa, Allam Sherif, Prayudi Sinatrya D., Zalmout Iyad S., Memesh Abdullah, Alnajjar Mohammed I., Bahameem Ahmed A., Kaminski Michael A.

Annales Societatis Geologorum Poloniae

2025

Vol. 95, No. 2

141--152

Agglutinated foraminifera with complex internal structures represent key components of deep-marine benthic assemblages and are important tools for biostratigraphic and palaeoenvironmental reconstructions. The subfamily Pavonitininae, which includes the genera Pavonitina and Pavopsammia, previously has been documented mainly from Oligocene to Miocene successions of the central Paratethys, West Africa, and the Atlantic margins. This study reports the first stratigraphically well-constrained record of Pavonitininae from the upper Eocene (Biozone E14) Rashrashiyah Formation in the Sirhan-Turayf Basin of northwestern Saudi Arabia. The recovered assemblage includes Pavopsammia flabellum, Pavonitina styriaca, Pavonitina biarritzensis, and Pavonitina kiscelliana. The morphological characteristics of these species, preserved in marly limestones and calcareous claystones, show transitions from an initially coiled arrangement to biserial and uniserial arrangements, reflecting different evolutionary phases of the group. Their co-occurrence extends their known stratigraphic range into the Priabonian and shows that important morphological modifications emerged earlier than previously thought, providing the oldest reliably dated record of the Pavonitininae. Palaeoceanographic changes, such as carbonate compensation depth deepening and oxygen minimum zone expansion, along with the Sirhan-Turayf Basin’s palaeogeographic location along the southern Tethyan margin, probably encouraged diversification of the Pavonitininae and their dispersal towards the Paratethys and Atlantic Ocean. These findings refine the evolutionary history, palaeobiogeography, and palaeoecological significance of the Pavonitininae, and improve their application in biostratigraphic and palaeoenvironmental studies of Paleogene deep-marine deposits.

Bulbobaculites attashensis sp. nov., a new agglutinated foraminifera from the Middle Jurassic D7 Attash Member of the Dhruma Formation, Central Saudi Arabia

Jalloh Chernoh Mohamed, Hikmahtiar Syouma, Korin Asmaa, Prayudi Sinatrya D., Fheed Adam, Kaminski Michael A.

Annales Societatis Geologorum Poloniae

2024

Vol. 94, No. 4

399--408

The new species Bulbobaculites attashensis sp. nov. is described from the rhythmite limestone and marl sediments of the D7 Attash Member of the Middle Jurassic (lower Callovian) Dhruma Formation in Central Saudi Arabia. This species is characterized by its coarsely agglutinated wall, streptospiral initial coiling, and a distinct bulbous initial coil. The occurrence of this species in limestone-marl rhythmite deposits suggests its adaptation to fluctuating environmental conditions, including changes in water depth, salinity, and nutrient flux, associated with rhythmic sedimentation.