Head of the Paleoceanographic team, Dr. Sc. Elena V. Ivanova.

The Paleoceanographic team was organized within the Laboratory of Geodynamics and Paleoceanography in 2005, after the reorganization of the Laboratory of Ore Genesis and Paleoceanography. The main research subjects of the team are the high resolution paleoceanographic reconstructions in the different areas of the World Ocean, global correlations, and teleconnections. The group headed by Dr. Sc. Elena Ivanova consists of seven persons, including Emeritus Professor Ivar Murdmaa, researches and PhD students. Current research is mainly focused on the Tropical and North Pacific, Tropical and South Atlantic, Barents and Black seas.

Recent projects

• Branch of the Earth Sciences of the Russian Academy of Sciences: Reconstruction of the critical events associated to the interaction of the global thermohaline circulation and climate during the Pleistocene based on the paleoceanographic proxies (PI - E.Ivanova, 2010-2012).
• Program N 20/21 "Basic problems in Oceanology" by Presidium of the Russian Academy of Science, subject: Reconstructions of the postglacial oceanic environments (PI: E.Ivanova and I.Murdmaa, 2010-2011).
• RFBR 10-05-91332-DFG_а: Mechanisms of the postglacial climatic variability in the Barents Sea (coordinators : E. Ivanova and M. Latif, 2010)
• RFBR 11-05-01000_a: Theoretical and empirical research of the oceanic segment of sedimentosphere (PI- I.Murdmaa, 2011-2013)
• RFBR 06-05-64803-а: Foraminiferal assemblages in postglacial sedimentary facies of the Barents Sea: environmental factors and burial conditions (PI - E.Ivanova, 2006-2008).
• RFBR 06-05-22000-CNRS_а (PICS): Impact of rapid climate changes on the hydrology and biodiversity in the Tropical Pacific (coordinators E. Ivanova and L. Vidal, 2006-2008)
• IGCP 521: Black Sea - Mediterranean Corridor during the last 30 ka: sea-level oscillations and human adaptation (coordinators V. Yanko-Hombach and P. Dolukhanov)
• a joint Russian-German Project KALMAR (Kurile-Kamchatka and Aleutean Marginal Sea-Island Arc Systems: Geodynamic and Climate Interaction in Space and Time, coordinators B.Baranov and C.Dullo).
• international project CLIMSEAS (Climate Change in Inland Seas: Phenomena, Feedback and Uncertainties, The Physical Science Basis, coordinators E. Roget and P. Zavyalov, 2011-2014).
  

Marine scientific cruises

• cruise 32 by RV Akademik Ioffe, Trans-Atlantic (Kaliningrad, Russia-Ushuaia, Argentina), October-November 2010 (head of the sedimentological team I.Murdmaa, participant E. Ivanova)
• cruise 33 by RV Akademik Ioffe, Trans-Atlantic (Ushuaia, Argentina-Schetsin, Poland), March-April 2011 (co-chief I.Murdmaa , head of the geological team E. Ivanova)
• RV Ashamba, NE Black Sea, July, 2009 and August 2010 (co-chief E.Murdmaa)
  

The most important research results obtained in 2008 - 2011

High-resolution paleoceanographic, micropaleontological, sedimentological and paleoenvironmental studies of Late Pleistocene to Holocene sediments have been carried out in the Eastern Equatorial Pacific, Barents Sea, Kara Sea, Black Sea and Arabian Sea. Major results obtained in 1995-2008 in low and high latitudes, and an extensive review of relevant international publications are summarized in the revised and extended version of the monograph "The global thermohaline circulation" by E. Ivanova (Springer, 2009, 314 p). The book describes what is known about the global thermohaline circulation and its variability through the last glacial-interglacial cycle. The topics addressed include the glacial-interglacial and millennial variability of climate and meridional overturning circulation in the North Atlantic, its impact on the postglacial environments in the Arctic Seas, relation to the monsoonal circulation in the tropical Indo-Pacific, remote correlation of paleoceanographic events, biological productivity changes in the low latitudes, global teleconnections and their possible mechanisms, including a bipolar seesaw.

Multi-proxy micropaleontological, lithological and geochemical studies have been carried out on four giant deep-sea cores from the tropical Pacific from the water depth range 600 - 1960m. According to the oxygen isotope and paleomagnetic age models developed by our French partners from CEREGE and supported by the AMS 14C dates, the cores recovered Late Quaternary sediments (within the last 270 ka), with downcore sampling in 5-cm intervals providing millennial to centennial resolution paleoreconstructions. Foraminiferal-based sea-surface temperatures are estimated by the modern analogue technique whereas biological productivity is qualitatively evaluated using indicator planktic and benthic foraminiferal species. The magnitude of glacial-interglacial paleotemperature variations reached 2-3 °C in the west and about 3-5 °C in the east of the tropical Pacific. Unlike the Western Pacific Warm Pool, enhanced productivity values in the Eastern Equatorial Pacific are associated with slowdown of the Atlantic meridional overturning during Heinrich events, thus reflecting atmospheric and oceanic teleconnections. High productivity values are typical for terminations, i.e. for the intervals of rearrangement of the global thermohaline circulation. More vigorous ventilation of the intermediate water that bathes the Cocos Ridge is deduced from the increased content of epibenthic foraminifera during the Bolling-Allerod interstadial (PI - Dr.E.Ivanova). The chemical composition and age of the volcanic ash layers has been determined from core MD05-2920 in the western tropical Pacific. The important role of settling of thick diatom mats in the deposition of laminated sapropels and in reduction of the benthic foraminiferal fauna is established from the core MD02-2508 retrieved from the continental slope of Baja California (PI - Prof. I.Murdmaa).

Postglacial paleoenvironments have been reconstructed for the SW Barents Sea based on multi-proxy time series from the AMS-14C dated core PSh 5159N/R in cooperation with Norwegian partners from the Bjerknes Centre for Climate Research, University of Bergen. Comparison of modelling results with the new paleo proxy time series has been carried out in cooperation with the reserachers from IFM-GEOMAR and IFA RAS to obtain better insights into the dynamics and mechanisms of postglacial climate changes in the Barents Sea. The Atlantic water inflow (as a signature of the Atlantic meridional overturning) in different layers of the water column, solar forcing, atmospheric forcing including the North Atlantic Oscillation (NAO) and sea-ice feedback were considered as the most plausible candidates to explain the amplitudes of paleotemperature changes and the rapid climate transitions. Paleodata and modeling results collectively point to Atlantic water inflow and hence, to the Atlantic meridional overturning circulation (AMOC) as one of the major factors of the Holocene climatic variability in the Barents Sea on millennial to decadal time scales (PI- Dr. E. Ivanova).

The study of living benthic foraminifers from the box-cores obtained in the Barents Sea ascertained that several species penetrate down to 8 - 10 cm subbottom depth searching for a favourable microhabitat. The penetration depth on the Barents Sea shelf is by 2 - 4 cm deeper than that on the continental slope, likely because of higher sedimentation rates on the shelf, as well as owing to bioturbation (PI- Dr. E. Ivanova).

Four paleoceanographic events are distinguished during the Holocene based on changes in macro- and microfossil assemblages studied from three AMS 14C dated sediment cores (Ak 521, 522, 2571) from the NE Black Sea shelf. Centennial-millennial variations in bottom-water salinity are resolved in the area. The first paleoceanographic event is associated with the pulse of Mediterranean water previously established at about 9.8-9.3 14C ka BP. The second event is represented by a replacement of a brackish benthic fauna with marine species between 8.4 and 6.9 14C ka BP, indicating a gradual increase in salinity. The third event is marked by a salinity rise to modern values by 6.5 14C ka BP following by a decrease within the interval ~6.4-5.3 14C ka BP. The fourth event is marked by a further increase in bottom-water salinity to modern values indicated by the ostracod assemblages at ~ 5.3 14C ka BP, after which only minor salinity fluctuations are observed (PI: Prof. I.Murdmaa and Dr. E. Ivanova).

Changes of paleoceanographic conditions on Shirshov Ridge, Western Bering Sea, are inferred over the last 50 kyr from high-resolution study of planktic and benthic foraminiferal assemblages and IRD from the upper part of a 18m-long piston core SO201-2-85KL (57°30.30'N, 170°24.79'E, water depth 968 m) in cooperation with German and Russian participants of the KALMAR project. The results suggest pronounced glacial-interglacial and millennial-scale variations in the surface bioproductivity, bottom-water ventilation and sea ice/iceberg rafting. The glacial interval is characterized by abundant terrigenous input, including IRD transported by the sea ice and icebergs, and by moderate biological productivity with the seasonal pulses. Factor analyses of the benthic fauna revealed a remarkable difference between glacial and interglacial assemblages. Changes in benthic assemblages suggest high bioproductivity and reduced ventilation over the interglacial. Meanwhile, the low-diversity planktic foraminiferal assemblages dominated by polar species indicate a generally cold surface-water layer over the time interval studied. The most remarkable environmental changes are shown to be associated to reorganization of the Bering Sea circulation during the glacial termination (PI - Dr. E. Ivanova).

Scientists of the Paleoceanographic team, together with the Laboratory of Seismic Stratigraphy, organized and carried out Trans-Atlantic geological-geophysical expeditions on R.V. "Akademik Sergei Vavilov" (cruise 26) and "Akademik Ioffe" (cruises 32 and 33) in 2009 - 2011. The methodology of high-resolution seismic facies study by the new seismic profiler SES-2000 deep was elaborated based on correlation of the seismic records with Quaternary sediment sections recovered by the deep-sea drilling boreholes (cruise ASV-26) and our cores (cruises AI-32, AI-33). The cores recovered contourites, turbidites, and hemipelagites from Kein, Romanche, and Vema deep-sea channels through which Antarctic bottom water penetrates into the South and Central Atlantic (AI-32), as well as from the South American continental rise (AI-33) (PI - Prof. I.O.Murdmaa).