geochemistry of sedimentation in the rusalca region as an indicator of paleooceanological and...
TRANSCRIPT
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GEOCHEMISTRY OF SEDIMENTATION GEOCHEMISTRY OF SEDIMENTATION IN THE RUSALCA REGION AS AN INDICATOR IN THE RUSALCA REGION AS AN INDICATOR
OF PALEOOCEANOLOGICAL ANDOF PALEOOCEANOLOGICAL AND GEODYNAMIC PROCESSESGEODYNAMIC PROCESSES
Astakhov, A.S.,Astakhov, A.S., Kolesnik, A.N., Bosin, A.A., and Kolesnik, O.N.Kolesnik, A.N., Bosin, A.A., and Kolesnik, O.N.
St. Petersburg, RussiaMay 21-23, 2013
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Part I:Part I:
Materials for studyMaterials for study
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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).
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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.
a b
c d
Bot
tom
sed
imen
ts:
surf
ace
laye
r &
cor
es
MATERIALS FOR STUDY
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MATERIALS FOR STUDY
“New” сores of bottom sediments
a b
а – HC-1 core of 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).
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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).
Samples of the Chukchi Sea ferromanganese nodules (FMNs)
MATERIALS FOR STUDY
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Fragment of carbonate rock from the northeastern Chukchi Sea
а – overview; b – cross-sectional view
a b
MATERIALS FOR STUDY
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surface layer of bottom sediments
n=375
ferromanganese nodules
bottom sediment
cores
bottom sediment
mini-cores (up to 60 cm)
fragment of carbonate
rock
n>145
n=30
n=20
n=1
samples, results of studying of which are published by other researchers
Our database of geological material from the Chukchi Sea
Legend
samples received from other organizations
RU
SA
LC
A p
roje
ct
up to the year 2009
year 2009
year 2012
MATERIALS FOR STUDY
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Part II:Part II:
Results. Surface layer of Results. Surface layer of bottom sedimentsbottom sediments
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RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
Characteristic Si Ti Al Fe Mn Mg Ca
Number of samples analyzed
244 195 244 223 223 237 196
Percentage of data published (in numbers)
92.2 92.3 92.2 93.3 93.3 94.9 92.3
References(see slide 12)
2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3
Characteristic K Na P Opal TOC Ba Co
Number of samples analyzed
163 123 103 174 275 196 223
Percentage of data published (in numbers)
90.8 87.8 85.4 42.5 94.5 92.3 93.3
References (see slide 12)
3 3 3 1, 2 1-3 2, 3 2, 3
Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea
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Characteristic Cr Cu Ni Pb Sr V Y
Number of samples analyzed
223 223 223 194 237 223 196
Percentage of data published (in numbers)
93.3 93.3 93.3 90.7 93.7 93.3 92.3
References(see slide 12)
2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3
Characteristic Yb Zn Zr La Mo Au Ag
Number of samples analyzed
196 223 176 237 103 21 141
Percentage of data published (in numbers)
92.3 93.3 91.5 94.9 85.4 100 74.5
References(see slide 12)
2, 3 2, 3 2, 3 2, 3 3 1 1, 3
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea (continued)
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Characteristic Pt Os Ir Ru Cd Hg
Number of samples analyzed
21 21 21 21 103 280
Percentage of data published (in numbers)
100 100 100 100 85.4 94.6
References(see below)
1 1 1 1 3 2, 3
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 the bottom sediments of the Chukchi Sea. Geochemistry International 48 (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.
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea (continued)
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Characteristic Geochemical indicators
Oxic waters Mn, Mn/Al, (Fe+Mn)/Ti,
Ca, Sr, Hg, Zn, Ni, V
Anoxic-euxinic (H2S) waters Mo/Mn, Mo, V/Mn, Ag
Primary production Opal, Br, Ba
Seasonal ice sheet Opal, Ba, Ba/Al
System of cold and warm currentsCa, TOC (total organic carbon),
Opal, Zn
Active geodynamics(cold and hydrothermal vents)
Fe, (Fe+Mn)/Ti, Hg, TOC
Some geochemical indicators of environmental conditions in the Chukchi Sea basin
We outlined in red those geochemical indicators that will be considered below.
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
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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
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
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TOC content
in the surface layer of bottom
sediments from the Chukchi Sea
versus cold and warm
currents, and some geological structures
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
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Ca content
in the surfacelayer of bottom
sediments from the Chukchi Sea
versuscold and warm
currents
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
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Sr content
in the surfacelayer of bottom sediments from the Chukchi Sea
versus cold and warm
currents
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
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(Fe+Mn)/Ti values
for the surface layer of bottom sediments from
the Chukchi Sea and adjacent Arctic basin
versus some geological
structures
RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
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RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
Zn content
in the surfacelayer of bottom sediments from the Chukchi Sea
versuscold and warm
currents, and geological
structures
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RESULTS. SURFACE LAYER OF BOTTOM SEDIMENTS
V content
in the surfacelayer of bottom sediments from the Chukchi Sea
versuscold and warm
currents, and geological
structures
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Part III:Part III:
Results. Bottom sediment coresResults. Bottom sediment cores
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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))
RESULTS. BOTTOM SEDIMENT CORES
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 the adjacent areas of the Arctic Ocean during the RUSALCA-2009 expedition. Russian Journal of Pacific Geology, 4 (6), 532–537.
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Eux
inic
-oxi
c ci
rcle
1E
uxin
ic-o
xic
circ
le 2
2-3
33-
4 Stratigraphy, XRF chemistry, and environmental reconstruction in cores
of the Chukchi Sea borderland
RESULTS. BOTTOM SEDIMENT CORES
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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.
RESULTS. BOTTOM SEDIMENT CORES
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RESULTS. BOTTOM SEDIMENT CORES
Paleoflora remains in sediments of core 12
CompositionAgeCore
interval
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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.
RESULTS. BOTTOM SEDIMENT CORES
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Part IV:Part IV:
Results. Ferromanganese nodulesResults. Ferromanganese nodules
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RESULTS. FERROMANGANESE NODULES
Characteristic St. 1 St. 3 St. 4 St. 5
Morphology,microstructure
+ + + ±
Chemical composition + + + –
Mineral composition (main minerals)
+ + + ±
Asseccory mineralization
+ + + ±
References 1, 2 1, 2 1, 2 1, 2
Our database on the Chukchi Sea ferromanganese nodules
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.
+ data obtained and published; ± data obtained, but not published; – no data.
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RESULTS. FERROMANGANESE NODULES
elem
ent c
onte
nt, %
st. 1 st. 3 st. 4
Fe
Mn
Macroelements in the Chukchi Sea ferromanganese nodules
Si
Legend
Al
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RESULTS. FERROMANGANESE NODULES
Trace elements in the Chukchi Sea ferromanganese nodules
elem
ent c
onte
nt, p
pm
Legend
FMN, st. 1
FMN, st. 3
FMN, st. 4
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RESULTS. FERROMANGANESE NODULES
– quartz SiO2
– strengite FePO4·2H2O– plagioclases (100-n)NaAlSi3O8 + nCaAl2Si2O8
Mineral compositionof the Chukchi Sea ferromanganese nodules
Legend
Diffraction pattern of FMN from the northern
Herald Canyon (st. 1)
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RESULTS. FERROMANGANESE NODULES
Matrix of FMNs from the Chukchi Sea (based on the results of electron microprobe analysis)
Chemical composition of matrix
elem
ent s
hare
in c
hem
ical
com
poun
d
Mn Fe Si Al
Na Mg
Surface of FMN polished section
K Ca
Cl F P
area no.
O
1
2
3
4 5
6
Manganese mineral phases are likely amorphous (they were detected only by means of electron microprobe analysis).
Legend
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RESULTS. FERROMANGANESE NODULES
Micrograins of nonferrous, noble, and rare-earth metals in the Chukchi Sea FMNs
Mnz – monazite (Ce, La…)PO4, Q – quartz SiO2, Zrn – zircon ZrSiO4.
100 µm 100 µm
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Part V:Part V:
Results. Authigenic carbonatesResults. Authigenic carbonates
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RESULTS. AUTHIGENIC CARBONATES
Characteristic Fragment of carbonate rock, st. 4
Morphology, microstructure ±
Chemical composition ±
Mineral composition (main minerals) ±
Asseccory mineralization ±
Isotopic composition of carbon (δC13) and oxygen (δO18)
±
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 ).
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Part VI:Part VI:
Our interestsOur interests
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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.