The micropaleontological record of marine early Eocene oil shales from Jordan

摘要

AbstractCore OS-28 located in central Jordan offers an expanded record of calcareous nannofossils and benthic foraminifera for the early Eocene of the southern Tethys. The oil shale succession of the studied interval covers calcareous nannofossil biozones NP10, NP11, NP12 and NP13. Microfossils document the biotic response of calcareous nannofossils and benthic foraminifera to short and long term warming trends of the early Eocene following the Paleocene-Eocene Thermal Maximum (PETM). On a global scale, two early Eocene short term shifts to higher atmospheric CO2concentration are recorded by negative δ13C excursions. These are known as Eocene Thermal Maximum 2 and 3 (ETM2, ETM3). Stable isotope records (δ13Corg, δ13Ccarb, δ18Ocarb) from the study area do not show these negative excursions, which elsewhere can be correlated with the two hyperthermal events known from early Eocene successions. The absence of negative δ13C signals otherwise typical for ETM2 and ETM3 is explained by a diagenetic alteration of the isotope signal after deposition.High abundances of the nannofossil taxonSphenolithusspp. in biozone NP10 indicate less fertile conditions for this interval than for the overlying biozone NP11. Throughout biozones NP11 to NP13Coccolithus pelagicusandToweiusspp. are the dominant taxa of the assemblages, suggesting a m