People

Research Interests:

Current Research
Past climate changes, paleoceanography and biomineralization.

My general research interests cover a broad spectrum of the Earth Sciences with particular emphasis on past climate changes, paleoceanography and biomineralization.
Developing a proxy for reconstructing past ocean seasonality using foraminiferal geochemistry. The amplitude of seasonal and inter-annual changes in seawater temperature and salinity is one of the major characteristics of the coupled ocean-climate system. Reconstructing these crucial oceanographic parameters is of high priority but remains mostly unachieved.
My colleagues and I study the natural variability in geochemical signals of modern and fossil planktonic foraminiferal populations using various microanalytical techniques such as secondary ion mass spectrometry (SIMS) and laser ablation mass spectrometry. We aim to accurately quantify the biological component within Mg/Ca variability using top quality sediment trap samples (fossil population) with bi-weekly resolution and also core-top samples (modern population) collected directly below the sediment trap.
Paleoceanography of the Tropical Pacific its relationship with ENSO system. In the modern climate system, the El Niño Southern Oscillation (ENSO) is the second largest source of climate variability after the solar cycle. Its 2-7 year oscillations from positive (El Niño) to negative (La Niña) phases leads to a large redistribution of heat and moisture fluxes across the planet resulting in severe social and economic impacts. Understanding its response to increased concentrations of greenhouse gases is crucial for predicting future climate and its social and economic impacts. Effective modelling or testing of predictions in this area using current global circulation climate models is hampered by the absence of a long time observational record from the Tropical Pacific. My colleagues and I investigate the link between Tropical Pacific paleoceanography and past climate changes during the last 25kyr. We use the geochemistry of planktonic foraminifera to reconstruct the mean state of the Tropical Pacific (the long term average distribution of oceanographic and atmosphere parameters across the Equatorial Pacific) and ENSO variability. Results of this work provide a unique insight into the evolution of the ENSO system during the last 25 kyr and its significant influence on global climate changes.

Selected publications:

Langer, Gerald and Sadekov, Aleksey and Thoms, Silke and Mewes, Antje and Nehrke, Gernot and Greaves, Mervyn and Misra, Sambuddha and Bijma, Jelle and Elderfield, Henry (2015) Li partitioning in the benthic foraminifera Amphistegina lessonii. Geochemistry, Geophysics, Geosystems. n/a-n/a. ISSN 15252027 DOI 10.1002/2015GC006134

Sadekov, Aleksey Yu. and Bush, Flora and Kerr, Joanna and Ganeshram, Raja and Elderfield, Henry (2014) Mg/Ca composition of benthic foraminifera Miliolacea as a new tool of paleoceanography. Paleoceanography, 29 (10). 2014PA002654. ISSN 1944-9186 DOI 10.1002/2014PA002654

Gabitov, Rinat I. and Rollion-Bard, Claire and Tripati, Aradhna and Sadekov, Aleksey (2014) In situ study of boron partitioning between calcite and fluid at different crystal growth rates. Geochimica Et Cosmochimica Acta, 137. pp. 81-92. ISSN 0016-7037 DOI 10.1016/j.gca.2014.04.014

Gabitov, R. I. and Sadekov, A. and Leinweber, A. (2014) Crystal growth rate effect on Mg/Ca and Sr/Ca partitioning between calcite and fluid : An in situ approach. Chemical Geology, 367. pp. 70-82. ISSN 0009-2541 DOI 10.1016/j.chemgeo.2013.12.019

Branson, Oscar and Redfern, Simon A. T. and Tyliszczak, Tolek and Sadekov, Aleksey and Langer, Gerald and Kimoto, Katsunori and Elderfield, Henry (2013) The coordination of Mg in foraminiferal calcite. Earth and Planetary Science Letters, 383. pp. 134-141. ISSN 0012-821X DOI 10.1016/j.epsl.2013.09.037

Sadekov, Aleksey and Ganeshram, Raja and Pichevin, Laetitia and Berdin, Rose and McClymont, Erin and Elderfield, Henry and Tudhope, Alexander W. (2013) Palaeoclimate reconstructions reveal a strong link between El Nino-Southern Oscillation and Tropical Pacific mean state. Nature Communications, 4 (2692). ISSN 2041-1723 DOI 10.1038/ncomms3692

Hathorne, Ed C. and Gagnon, Alex and Felis, Thomas and Adkins, Jess and Asami, Ryuji and Boer, Wim and Caillon, Nicolas and Case, David and Cobb, Kim M. and Douville, Eric and deMenocal, Peter and Eisenhauer, Anton and Garbe-Schönberg, Dieter and Geibert, Walter and Goldstein, Steven and Hughen, Konrad and Inoue, Mayuri and Kawahata, Hodaka and Kölling, Martin and Cornec, Florence L. and Linsley, Braddock K. and McGregor, Helen V. and Montagna, Paolo and Nurhati, Intan S. and Quinn, Terrence M. and Raddatz, Jacek and Rebaubier, Hélène and Robinson, Laura and Sadekov, Aleksey and Sherrell, Rob and Sinclair, Dan and Tudhope, Alexander W. and Wei, Gangjian and Wong, Henri and Wu, Henry C. and You, Chen-Feng (2013) Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements. Geochemistry Geophysics Geosystems, 14 (9). pp. 3730-3750. ISSN ESSN: 1525-2027 DOI 10.1002/ggge.20230

Gabitov, Rinat I. and Watson, E. Bruce and Sadekov, Aleksey (2012) Oxygen isotope fractionation between calcite and fluid as a function of growth rate and temperature: An in situ study. Chemical Geology, 306–30. pp. 92-102. ISSN 0009-2541 DOI 10.1016/j.chemgeo.2012.02.021

Russon, T. and Elliot, M. and Sadekov, A. and Cabioch, G. and Corrge, T. and De Deckker, P. (2011) The mid-Pleistocene transition in the subtropical southwest Pacific. Paleoceanography, 26 (1). p. 1211. DOI 10.1029/2010PA002019

Russon, T. and Elliot, M. and Sadekov, A. and Cabioch, G. and Corrge, T. and De Deckker, P. (2010) Inter-hemispheric asymmetry in the early Pleistocene Pacific warm pool. Geophysical Research Letters, 37 (11). p. 11601. DOI 10.1029/2010GL043191

Sadekov, A. Y. and Eggins, S.M. and Klinkhammer, G.P. and Rosenthal, Y. (2010) Effects of seafloor and laboratory dissolution on the Mg/Ca composition of Globigerinoides sacculifer and Orbulina universa tests – A laser ablation ICPMS microanalysis perspective. Earth and Planetary Science Letters, 292 (3-4). pp. 312-324. ISSN 0012-821X DOI 10.1016/j.epsl.2010.01.039

Sadekov, A. and Eggins, S.M. and De Deckker, P. and Ninnemann, U. and Kuhnt, W. and Bassinot, F. (2009) Surface and subsurface seawater temperature reconstruction using Mg/Ca microanalysis of planktonic foraminifera Globigerinoides ruber, Globigerinoides sacculifer, and Pulleniatina obliquiloculata. Paleoceanography, 24 (3). PA3201. DOI 10.1029/2008PA001664

Pena, L.D. and Cacho, I. and Calvo, E. and Pelejero, C. and Eggins, S. and Sadekov, A. (2008) Characterization of contaminant phases in foraminifera carbonates by electron microprobe mapping. Geochemistry Geophysics Geosystems, 9 (7). DOI 10.1029/2008GC002018

Sadekov, A. and Eggins, S.M. and De Deckker, P. and Kroon, D. (2008) Uncertainties in seawater thermometry deriving from intratest and intertest Mg/Ca variability in Globigerinoides ruber. Paleoceanography, 23 (1). p. 1215. DOI 10.1029/2007PA001452

Kopaevich, L.F. and Beniamovski, V.N. and Sadekov, A.Yu. (2007) Middle Coniacian-Santonian foraminiferal bioevents around the Mangyshlak Peninsula and Russian Platform. Cretaceous Research, 28 (1). pp. 108-118. DOI 10.1016/j.cretres.2006.05.018

Sadekov, A.Yu. and Eggins, S.M. and De Deckker, P. (2005) Characterization of Mg/Ca distributions in planktonic foraminifera species by electron microprobe mapping. Geochemistry Geophysics Geosystems, 6 (12). ISSN 1525-2027 DOI 10.1029/2005GC000973

Sadekov, A.Yu. and Alekseev, A.S. and Martinez-Ruis, F. and Ivanov, M.K. and Comas, M. (2005) A sapropelic interlayer in quaternary sediments of the western Balearic Basin (Mediterranean Sea) and depositional environments inferred from planktonic foraminifera. Stratigraphy and Geological Correlation, 13 (2). pp. 212-220.

Eggins, S.M. and Sadekov, A. and De Deckker, P. (2004) Modulation and daily banding of Mg/Ca in Orbulina universa tests by symbiont photosynthesis and respiration: A complication for seawater thermometry? Earth and Planetary Science Letters, 225 (3-4). pp. 411-419. ISSN 0012-821X DOI 10.1016/j.epsl.2004.06.019

Ovsyannikov, D.O. and Sadekov, A.Yu. and Kozlova, E.V. (2003) Rock fragments from mud volcanic deposits of the Gulf of Cadiz: An insight into the Eocene-Pliocene sedimentary succession of the basin. Marine Geology, 195 (1-4). pp. 211-221. DOI 10.1016/S0025-3227(02)00689-8

Ovsiannikov, D. O. and Sadekov, A. and Kozlova, E. (2002) Particularities of lithological composition of big clasts from the Yuma mud volcano (Gulf of Cadiz). Vestnik Moskovskogo Universiteta, Geologia, 26. pp. 25-32. ISSN PRINT: 0145-8752