Quantitative analysis of calcareous nannofossil assemblages across the Campanian/Maastrichtian boundary interval at Kladorub (NW Bulgaria): preliminary results

An investigation of the variations in calcareous nannofossil abundances across the Campanian/Maastrichtian boundary interval at Kladorub (NW Bulgaria) has been carried out. The section has an established detailed biostratigraphic framework, based on calcareous nannofossils, and also contains the Campanian–Maastrichtian Boundary Event. The analysis shows that the nannofloras are dominated by Prediscosphaera cretacea, followed by Watznaueria barnesiae, Micula staurophora, Arkhangelskiella spp. and Cribrosphaerella ehrenbergii.

Palynological and calcareous nannofossil investigation of the Gosau Group deposits from three boreholes in the Vienna Basin, Austria

Palynological and calcareous nannofossil investigations on samples from the basal part of the Gosau Group succession in three boreholes (Glinzendorf T1, Gänserndorf T3 and Markgraf Neusiedl T1) in the Vienna Basin provide calibrated age assessment of late Coniacian to early Campanian age for this thick non-marine to marginal-marine siliciclastic interval.

Impact of the Middle Eocene Climatic Optimum (MECO) on Foraminiferal and Calcareous Nannofossil Assemblages in the Neo-Tethyan Baskil Section (Eastern Turkey): Paleoenvironmental and Paleoclimatic Reconstructions

The Middle Eocene Climatic Optimum (MECO; ~40 Ma), which interrupted for ~500–600 kyr the long-term cooling trend culminating at the Eocene/Oligocene boundary, still requires a comprehensive understanding of the biotic resilience. Here we present a high-resolution integrated foraminiferal and calcareous nannofossil study across the MECO from the expanded and continuous Tethyan Baskil section (eastern Turkey) that offers a complete magneto-biostratigraphic and geochemical framework. The five MECO phases identified reveal a transition from oligotrophic (pre-MECO) to eu-mesotrophic conditions, possibly related to accelerated hydrological cycle, during the initial MECO and MECO δ13C negative excursion phases. The MECO WARMING PEAK phase, marking the highest carbonate dissolution interval, records the most striking biotic changes, such as peak in warm and eutrophic nannofossils, virtual disappearance of the oligotrophic planktic foraminiferal large Acarinina and Morozovelloides, and peak in eutrophic deep dwellers Subbotina. Benthic foraminifera suggest in this phase an improvement in the quality of organic matter to the seafloor. The post-MECO phase shows only a partial recovery of the pre-event conditions. Large Acarinina and Morozovelloides did not recover their abundance, possibly due to cooler conditions in this phase. Our reconstruction reveals how paleoenvironment and marine biota from the studied Neo-Tethyan setting reacted to the MECO perturbations.

Calcareous Nannofossil Biostratigraphy and Ostracoda Paleoecology of Hartha Formation from Balad (1) well, Central Iraq

Seventeen samples of Hartha Formation in Balad (1) well, central Iraq, are studied on the basis of stratigraphic ranges of the recorded calcareous nannofossils for twenty species belonging to twelve genera. The studied section reveals three biozones arranged from oldest to youngest as follows; (1) Calculites ovalis Interval Biozone (CC19), (2) Ceratolithoides aculeus Interval Biozone (CC20), (3) Quadrum sissinghii Interval Biozone (CC21). These Biozones are correlated with other calcareous nannofossils biozones from both local and regional sections, leading to conclude the age of the Middle Campanian. Rerecorded eighteen ostracode species that belong to eleven genera are identified, all of which were previously recorded from Iraq and adjacent regions. The occurrence of these species leads to conclude a continental shelf environment, while they are typical of inner shelf-outer shelf depth.

Early to middle Eocene calcareous nannofossils of the SW Pacific: Paleobiogeography and paleoclimate

<p>Earth’s climate underwent a long-term warming trend from the late Paleocene to early Eocene (~58–51 Ma), with global temperature reaching a sustained maximum during the Early Eocene Climatic Optimum (EECO; 53–50 Ma). Geochemical proxies indicate tropical or warm subtropical sea-surface temperature (SST) conditions in middle and high latitudes in the early Eocene, implying a very low latitudinal temperature gradient. This study investigates whether calcareous nannofossil assemblages in the southwest (SW) Pacific provide evidence of these conditions at middle latitudes in the early to middle Eocene, particularly during the EECO. Specifically, this study documents the biogeographic changes of warm- and cold-water nannofossil species along a paleolatitudinal transect through the EECO to track changes in water masses/ocean circulation at that time. Early to middle Eocene calcareous nannofossil assemblages were examined from four sites along a latitudinal transect in the SW Pacific, extending from Lord Howe Rise in the north to Campbell Plateau in the south and spanning a paleolatitude of ~46–54°S. All of the sections studied in this project span nannofossil zones NP10–16 (Martini, 1971). The data indicate up to three regional unconformities through the sections: at mid-Waipara, Deep Sea Drilling Project (DSDP) Site 207 and 277, part or all of Zone NP10 (lower Waipawan) is missing; at Sites 207 and 277 a possible hiatus occurs within NP12 (upper Waipawan–lower Mangaorapan); and at all sites part or all of Zone NP15 (lower Bortonian) is missing. Results of this study indicate that nannofossil assemblages in the SW Pacific are more similar to floras at temperate to polar sites rather than those at tropical/subtropical sites. However, variations in the relative abundance of key species in the SW Pacific are broadly consistent with the trends seen in the geochemical proxy records: an increase in warm-water taxa coincided with the EECO, corroborating geochemical evidence for a temperature maximum in the SW Pacific during this interval. The increase in the abundance and diversity of warm-water taxa and decrease in the abundance of cool-water taxa through the EECO supports previous suggestions that a warm-water mass (northward of the proto-Tasman Front) extended to ~55°S paleolatitude during this interval in response to enhanced poleward heat transport and intensification of the proto-East Australian Current. At the southernmost site, DSDP Site 277, a relatively short-lived influx of warm-water taxa at ~51 Ma suggests that warm waters expanded south at this time. However, greater diversity and abundance of warm-water taxa throughout the EECO at DSDP Site 207, suggests that the proto-East Australian Current exerted greater influence at this latitude for a longer duration than at Site 277. An increase in the abundance of cool-water taxa and decrease in diversity and abundance of warm-water taxa at all sites is recorded following the termination of the EECO. This corresponds with the contraction of the proto-Tasman Front due to weakened proto-East Australian Current flow and associated amplification of the proto-Ross Gyre. Previous estimates of SSTs from geochemical proxies in the SW Pacific during the EECO indicate that there was virtually no latitudinal temperature gradient and temperatures were tropical to subtropical (>20°C). However, nannofossil data from this study indicate warm temperate conditions (~15–20°C) during the EECO, suggesting that a reduced latitudinal gradient was maintained through this interval, which is in agreement with climate models.</p>

Early to middle Eocene calcareous nannofossils of the SW Pacific: Paleobiogeography and paleoclimate

<p>Earth’s climate underwent a long-term warming trend from the late Paleocene to early Eocene (~58–51 Ma), with global temperature reaching a sustained maximum during the Early Eocene Climatic Optimum (EECO; 53–50 Ma). Geochemical proxies indicate tropical or warm subtropical sea-surface temperature (SST) conditions in middle and high latitudes in the early Eocene, implying a very low latitudinal temperature gradient. This study investigates whether calcareous nannofossil assemblages in the southwest (SW) Pacific provide evidence of these conditions at middle latitudes in the early to middle Eocene, particularly during the EECO. Specifically, this study documents the biogeographic changes of warm- and cold-water nannofossil species along a paleolatitudinal transect through the EECO to track changes in water masses/ocean circulation at that time. Early to middle Eocene calcareous nannofossil assemblages were examined from four sites along a latitudinal transect in the SW Pacific, extending from Lord Howe Rise in the north to Campbell Plateau in the south and spanning a paleolatitude of ~46–54°S. All of the sections studied in this project span nannofossil zones NP10–16 (Martini, 1971). The data indicate up to three regional unconformities through the sections: at mid-Waipara, Deep Sea Drilling Project (DSDP) Site 207 and 277, part or all of Zone NP10 (lower Waipawan) is missing; at Sites 207 and 277 a possible hiatus occurs within NP12 (upper Waipawan–lower Mangaorapan); and at all sites part or all of Zone NP15 (lower Bortonian) is missing. Results of this study indicate that nannofossil assemblages in the SW Pacific are more similar to floras at temperate to polar sites rather than those at tropical/subtropical sites. However, variations in the relative abundance of key species in the SW Pacific are broadly consistent with the trends seen in the geochemical proxy records: an increase in warm-water taxa coincided with the EECO, corroborating geochemical evidence for a temperature maximum in the SW Pacific during this interval. The increase in the abundance and diversity of warm-water taxa and decrease in the abundance of cool-water taxa through the EECO supports previous suggestions that a warm-water mass (northward of the proto-Tasman Front) extended to ~55°S paleolatitude during this interval in response to enhanced poleward heat transport and intensification of the proto-East Australian Current. At the southernmost site, DSDP Site 277, a relatively short-lived influx of warm-water taxa at ~51 Ma suggests that warm waters expanded south at this time. However, greater diversity and abundance of warm-water taxa throughout the EECO at DSDP Site 207, suggests that the proto-East Australian Current exerted greater influence at this latitude for a longer duration than at Site 277. An increase in the abundance of cool-water taxa and decrease in diversity and abundance of warm-water taxa at all sites is recorded following the termination of the EECO. This corresponds with the contraction of the proto-Tasman Front due to weakened proto-East Australian Current flow and associated amplification of the proto-Ross Gyre. Previous estimates of SSTs from geochemical proxies in the SW Pacific during the EECO indicate that there was virtually no latitudinal temperature gradient and temperatures were tropical to subtropical (>20°C). However, nannofossil data from this study indicate warm temperate conditions (~15–20°C) during the EECO, suggesting that a reduced latitudinal gradient was maintained through this interval, which is in agreement with climate models.</p>

Age constraints for the Trachilos footprints from Crete

We present an updated time frame for the 30 m thick late Miocene sedimentary Trachilos section from the island of Crete that contains the potentially oldest hominin footprints. The section is characterized by normal magnetic polarity. New and published foraminifera biostratigraphy results suggest an age of the section within the Mediterranean biozone MMi13d, younger than ~ 6.4 Ma. Calcareous nannoplankton data from sediments exposed near Trachilos and belonging to the same sub-basin indicate deposition during calcareous nannofossil biozone CN9bB, between 6.023 and 6.727 Ma. By integrating the magneto- and biostratigraphic data we correlate the Trachilos section with normal polarity Chron C3An.1n, between 6.272 and 6.023 Ma. Using cyclostratigraphic data based on magnetic susceptibility, we constrain the Trachilos footprints age at ~ 6.05 Ma, roughly 0.35 Ma older than previously thought. Some uncertainty remains related to an inaccessible interval of ~ 8 m section and the possibility that the normal polarity might represent the slightly older Chron C3An.2n. Sediment accumulation rate and biostratigraphic arguments, however, stand against these points and favor a deposition during Chron C3An.1n.