GEOCHEMISTRY OF SEDIMENTATION IN THE RUSALCA REGION AS AN INDICATOR OF PALEOOCEANOLOGICAL AND GEODYNAMIC PROCESSES Astakhov, A.S., Kolesnik, A.N., Bosin,

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

Part I:Part I:

Materials for studyMaterials for study

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).

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

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).

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

Fragment of carbonate rock from the northeastern Chukchi Sea

а – overview; b – cross-sectional view

a b

MATERIALS FOR STUDY

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

Part II:Part II:

Results. Surface layer of Results. Surface layer of bottom sedimentsbottom sediments

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


163 123 103 174 275 196 223


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

Characteristic Cr Cu Ni Pb Sr V Y


223 223 223 194 237 223 196


93.3 93.3 93.3 90.7 93.7 93.3 92.3


2, 3 2, 3 2, 3 2, 3 2, 3 2, 3 2, 3

Characteristic Yb Zn Zr La Mo Au Ag


196 223 176 237 103 21 141


92.3 93.3 91.5 94.9 85.4 100 74.5


2, 3 2, 3 2, 3 2, 3 3 1 1, 3


Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea (continued)

Characteristic Pt Os Ir Ru Cd Hg


21 21 21 21 103 280


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.


Our database on chemical composition of the surface layer of bottom sediments from the Chukchi Sea (continued)

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.


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


TOC content

in the surface layer of bottom

sediments from the Chukchi Sea


currents, and some geological structures


Ca content

in the surfacelayer of bottom

sediments from the Chukchi Sea

versuscold and warm

currents


Sr content

in the surfacelayer of bottom sediments from the Chukchi Sea


currents


(Fe+Mn)/Ti values

for the surface layer of bottom sediments from

the Chukchi Sea and adjacent Arctic basin

versus some geological

structures



Zn content


versuscold and warm

currents, and geological

structures


V content


versuscold and warm

currents, and geological

structures

Part III:Part III:

Results. Bottom sediment coresResults. Bottom sediment cores

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.

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


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.



Paleoflora remains in sediments of core 12

CompositionAgeCore

interval

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.


Part IV:Part IV:

Results. Ferromanganese nodulesResults. Ferromanganese nodules

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.


elem

ent c

onte

nt, %

st. 1 st. 3 st. 4

Fe

Mn

Macroelements in the Chukchi Sea ferromanganese nodules

Si

Legend

Al


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


– 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)


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


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

Part V:Part V:

Results. Authigenic carbonatesResults. Authigenic carbonates

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 ).

Part VI:Part VI:

Our interestsOur interests

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.

Documents

GEOCHEMISTRY OF SEDIMENTATION IN THE RUSALCA REGION AS AN INDICATOR OF PALEOOCEANOLOGICAL AND GEODYNAMIC PROCESSES Astakhov, A.S., Kolesnik, A.N., Bosin,