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Geochemistry of sedimentation

Geochemistry of sedimentation in the rusalca region as an indicator of paleooceanological and geodynamic processes Astakhov, A.S., Kolesnik, A.N., Bosin, A.A., and Kolesnik, O.N. St. Petersburg, Russia May 21-23, 201 3. Part I: Materials for study. MATERIALS FOR STUDY.

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Geochemistry of sedimentation

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  1. Geochemistry of sedimentation in the rusalca region as an indicator of paleooceanological andgeodynamic processes Astakhov, A.S.,Kolesnik, A.N., Bosin, A.A., and Kolesnik, O.N. St. Petersburg, Russia May 21-23, 2013

  2. Part I: Materials for study

  3. MATERIALS FOR STUDY Location of sampling sites 1 – sites where surface (0-3 cm) layer of bottom sediments was sampled, 2009-2012; 2 – sites where surface layer of bottom sediments was sampled, 2002-2006; 3 – sites where surface layer and cores of bottom sediments were sampled, 2009; 4 – sites where surface layer and cores of bottom sediments were sampled, 2012; 5 – sites where ferromanganese nodules were sampled, 2009; 6 – site where ferromanganese nodule was sampled, 2012; 7 – site where fragment of carbonate rock was sampled, 2009; 8 – sampling sites of surface layer of bottom sediments received from other organizations; 9 – sites where surface layer of bottom sediments was sampled (according to the literature).

  4. MATERIALS FOR STUDY a b Bottom sediments: surface layer & cores c d а – surface sediments sampled in the Bering Strait by means of the OCEAN grab sampler; b, с – cores of bottom sediments (formed under reductive conditions) sampled in the shallow Chukchi Sea; d – core of bottom sediments (formed under oxidizing conditions) from the Chukchi Plateau.

  5. MATERIALS FOR STUDY “New” сores of bottom sediments a b а – HC-1 coreof bottom sediments (formed under reductive conditions) sampled in the South-Chukchi Basin (RUSALCA-2012 expedition); b – HC-3 core of bottom sediments (formed under reductive conditions) sampled in Herald Canyon (RUSALCA-2012 expedition).

  6. MATERIALS FOR STUDY Samples of the Chukchi Sea ferromanganese nodules (FMNs) а b c 1 cm 1 cm 1 cm a–c, morphotypes: a, discoid (sts. 1 and 5, the northern Herald Canyon); b, cake-shaped (st. 3, the southern Herald Canyon); c, platy (st. 4, the northeastern Chukchi Sea shelf).

  7. MATERIALS FOR STUDY Fragment of carbonate rock from the northeastern Chukchi Sea а – overview;b – cross-sectionalview b a

  8. MATERIALS FOR STUDY Our database of geological material from the Chukchi Sea n=375 Legend n>145 n=30 samples, results of studying of which are published by other researchers n=20 samples received from other organizations n=1 fragment of carbonate rock up to the year 2009 bottom sediment mini-cores (up to 60 cm) year 2009 RUSALCA project bottom sediment cores year 2012 ferromanganese nodules surface layer of bottom sediments

  9. Part II: Results. Surface layer of bottom sediments

  10. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea

  11. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea (continued)

  12. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea (continued) Our major publications on chemical composition of the surface layer of the Chukchi Sea bottom sediments 1. Astakhov, A.S., Kolesov, G.M.,Dudarev, O.V., Ivanov, M.V., Kolesnik, A.N., 2010. Noble metals in thebottom sediments of the Chukchi Sea. Geochemistry International48 (12), 1208–1219. 2. Astakhov, A.S., Wang, Rujan, Crane, K., Ivanov, M.V., Gao, Aiguo, 2013. Lithochemical classification of the depositional environments of the Arctic Ocean (Chukchi Sea) using multivariate statistical techniques. Geochemistry International 51 (4), 269–289. 3. Astakhov, A.S., Gusev, E.A., Kolesnik, A.N., Shakirov, R.B., in press. Conditions of organic matter and metal accunulation in bottom sediments of the Chukchi Sea. Russian Geology and Geophysics.

  13. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Some geochemical indicators of environmental conditions in the Chukchi Sea basin We outlined in red those geochemical indicators that will be considered below.

  14. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Mn content in the surface layer of bottom sediments from the Chukchi Sea and adjacent Arctic basin versus cold and warm currents, ice and redox conditions, geological structures

  15. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS TOC content in the surface layer of bottom sediments from the Chukchi Sea versus cold and warm currents, and some geological structures

  16. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Ca content in the surface layer of bottom sediments from the Chukchi Sea versus cold and warm currents

  17. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Sr content in the surface layer of bottom sediments from the Chukchi Sea versus cold and warm currents

  18. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS (Fe+Mn)/Ti values for the surface layer of bottom sediments from the Chukchi Sea and adjacent Arctic basin versus some geological structures

  19. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS Zn content in the surface layer of bottom sediments from the Chukchi Sea versus cold and warm currents, and geological structures

  20. RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS V content in the surface layer of bottom sediments from the Chukchi Sea versus cold and warm currents, and geological structures

  21. Part III: Results. Bottom sediment cores

  22. RESULTS. BOTTOM SEDIMENTCORES The generalized bottom topography of the pockmark field on the Chukchi Plateau (the isolines are after the GEBCO) and bottom microrelief (according to the detailed multibeam echo sounding – (Mayer, Armstrong, 2007)) The core sampling sites (red circles) in the northern part of the pockmark field: left picture – bottom relief (according to hydroacoustic survey – (Mayer, Armstrong, 2007)); right one – structure of the upper part of sedimentary cover (according to geoacoustic profiling – (Mayer, Armstrong, 2007)) More details are in the paper:Astakhov, A.S., Bosin, A.A, Kolesnik, A.N., Korshunov, D.A., Crane,K., 2010. Geological investigations in the Chukchi Sea and theadjacent areasof the Arctic Ocean during the RUSALCA-2009 expedition. Russian Journal of Pacific Geology, 4 (6), 532–537.

  23. RESULTS. BOTTOM SEDIMENT CORES Euxinic-oxic circle 1 2-3 Euxinic-oxic circle 2 3 Stratigraphy, XRF chemistry, and environmental reconstruction in cores of the Chukchi Sea borderland 3-4

  24. RESULTS. BOTTOM SEDIMENT CORES Geochemical characteristics of sediments from the column 12 with the elements of the Quaternary stratigraphy (a) and site of the core sampling on the relief map (b) with a fragment of profilograph record obtained through the pockmark crater (b, inset map) 1 - intervals of sampling for diatomic analysis (filled circles indicate that remains of redeposited diatoms were detected, unfilled ones - that these remains were not detected). 2 - intervals of sampling for spore-pollen analysis and its results: unfilled rectangles indicate that spores and pollen were found, brown and green rectangles stand for that Paleozoic and Cretaceous spore-pollen complexes were detected, respectively. 3 - sediment coloration: dark brown - brown sediments, white - gray and olive green sediments, light brown - transitional differences of sediments, interlayering of brown and gray sediments,circles - finds of Quaternary benthic foraminifera remains. 4 - lithostratigraphic horizons (after [Polyak et al., 2011]) and their age range in accordance with marine oxygen isotope stages (OIS). Color fill shows intervals of sediments accumulated under various hydrochemical conditions: pink - anoxic conditions with hydrogen sulfide contamination; purple - anoxic conditions without hydrogen sulphide contamination involving brief oxidizing periods; yellow - oxidizing conditions.

  25. RESULTS. BOTTOM SEDIMENT CORES Paleoflora remains in sediments of core 12 Core interval Age Composition

  26. RESULTS. BOTTOM SEDIMENT CORES Model of fluid dynamics and development of the pockmark crater in regressive (b) and transgressive (a, c) stages (O2 and H2S - oxidizing and hydrogen sulfide anoxic conditions in near-bottom waters) 1-3 - Cenozoic, Mesozoic and Paleozoic sediments in the sedimentary cover, respectively. 4 - fluid-permeable vertical zone at the intersection of polygonal faults. 5 - gas-hydrates. 6 - free gas beneath the gas-hydrate layer. 7 - free gas and freshened waters in the place of decomposed gas-hydrates. 8 - zone of rock decompression. 9 - upper (a) and lower (b) bounds of gas-hydrate stability zone. 10 - direction of fluid migration. 11 - crater bottom subsidence. 12 - core 12 sampling site.

  27. Part IV: Results. Ferromanganese nodules

  28. RESULTS. FERROMANGANESE NODULES Our database on the Chukchi Sea ferromanganese nodules +data obtained and published;±data obtained, but not published; –no data. Our major publications on the Chukchi Sea ferromanganese nodules 1. Kolesnik, O.N., Kolesnik, A.N., 2013. Specific chemical and mineral composition of ferromanganese nodules from the Chukchi Sea. Russian Geology and Geophysics 54 (7), 653–663. 2.Kolesnik, A.N., Kolesnik, O.N., in press. Modern geological activity and ferromanganese ore formation in the Chukchi Sea. Journal of Volcanology and Seismology.

  29. RESULTS. FERROMANGANESE NODULES Macroelements in the Chukchi Sea ferromanganese nodules Legend Fe element content, % Mn Si Al st. 1 st. 3 st. 4

  30. RESULTS. FERROMANGANESE NODULES Trace elements in the Chukchi Sea ferromanganese nodules Legend FMN, st. 1 element content, ppm FMN, st. 3 FMN, st. 4

  31. RESULTS. FERROMANGANESE NODULES Mineral composition of the Chukchi Sea ferromanganese nodules Diffraction pattern of FMN from the northern Herald Canyon (st. 1) – quartzSiO2 Legend – strengiteFePO4·2H2O – plagioclases (100-n)NaAlSi3O8 + nCaAl2Si2O8

  32. 3 1 6 2 4 5 RESULTS. FERROMANGANESE NODULES Matrixof FMNs from the Chukchi Sea (based on the results of electron microprobe analysis) Surface of FMN polished section Chemical composition of matrix element share in chemical compound area no. Legend Si Al Mn Fe Mg Manganese mineral phases are likelyamorphous (they were detectedonly by meansof electron microprobe analysis). Na K Ca Cl F P O

  33. RESULTS. FERROMANGANESE NODULES Micrograins of nonferrous, noble, and rare-earth metals in the Chukchi Sea FMNs 100 µm 100 µm Mnz – monazite (Ce, La…)PO4, Q – quartz SiO2, Zrn – zirconZrSiO4.

  34. Part V: Results. Authigenic carbonates

  35. RESULTS. AUTHIGENIC CARBONATES Our database on the Chukchi Sea authigenic carbonates ±data obtained, but not published. Our plans to publish results of studying the Chukchi Sea authigenic carbonates Materials on chemical, mineral, and isotopic (δC13, δO18) composition of the fragment of carbonate rock from the northeastern Chukchi Sea are ready to be submitted to editors of one of the Russian scientific journals (there is also an English version of this journal ).

  36. Part VI: Our interests

  37. OUR INTERESTS We are interested in: 1 – obtaining quality sections (bottom sediment cores) from the deep Chukchi Sea borderland, as well as Makarov and Canadian basins for detailed paleooceanological analysis and environmental reconstruction for the last 100 kyr; 2 – obtaining quality sections (sediment cores and monoliths from box corers and multi corers) from the Chukchi and East Siberian shelf areas characterized by high sedimentation rates for detailed environmental reconstruction over the last millenniums and centuries and forecast future changes; 3 – carrying out complex geological and geophysical investigations on the outer shelf and slope of the Chukchi basin where graben-rift system of the Chukchi Sea and Charlie Cenozoic rift basin are joined; 4– obtaining more samples of bottom sediments and authigenic minerals from tectonically active zones of the RUSALCA region (graben-rift system of the Chukchi Sea, Herald and Barrow submarine canyons, Charlie and Northwind Cenozoic rift basins) to study (based on the results of complex mineral and geochemical analyses) specific fluid dynamic processes and estimate the impact of these processes on the region environment.

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