- Email: [email protected]
Micropaleontological assessment of sediments from Buor-Khaya Bay (Laptev Sea)
Accepted Manuscript Micropaleontological assessment of sediments from Buor-Khaya Bay (Laptev Sea) M.S. Obrezkova, I.B. Tsoy, I.P. Semiletov, N.K. Vagina, V.N. Karnaukh, O.V. Dudarev PII:
S1040-6182(18)30126-5
DOI:
https://doi.org/10.1016/j.quaint.2018.10.033
Reference:
JQI 7609
To appear in:
Quaternary International
Received Date: 2 March 2018 Revised Date:
6 July 2018
Accepted Date: 23 October 2018
Please cite this article as: Obrezkova, M.S., Tsoy, I.B., Semiletov, I.P., Vagina, N.K., Karnaukh, V.N., Dudarev, O.V., Micropaleontological assessment of sediments from Buor-Khaya Bay (Laptev Sea), Quaternary International (2018), doi: https://doi.org/10.1016/j.quaint.2018.10.033. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Micropaleontological assessment of sediments from Buor-Khaya Bay (Laptev Sea) Obrezkova M.S.1*, Tsoy I.B.1, Semiletov I.P.1,2 , Vagina N.K.1, Karnaukh V.N.1, Dudarev O.V.1,2 1
V.I. Ilyichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Science (POI FEB RAS), Vladivostok, 690041 Russia Tomsk National Research Polytechnic University, Tomsk, 634050 Russia *e-mail: [email protected]
Abstract
RI PT
2
The paper presents the first set of micropaleontological data from the Buor-Khaya Bay
SC
sediments in the southeastern part of the Laptev Sea, obtained from the bottom sediments through permafrost drilling. The study of diatoms and spore-pollen assemblages in Hole 1D-11 and Hole 4D-12, high-resolution seismic profiling, and lithological composition of the sediments have
M AN U
facilitated the identification of two different age strata formed under different conditions and dating to the Late Pleistocene and Holocene. The Pleistocene strata were composed of assorted sands with inclusions of dense dehydrated silt formed under continental conditions. The Holocene strata were composed mostly of clayey silt that had formed under transgressive conditions and significant influence of the Lena River runoff and Arctic tundra vegetation on the coast.
1. Introduction
TE D
Key words: Laptev Sea; sediments; permafrost drilling; diatoms; spores; Pleistocene-Holocene
EP
The study of the vast shallow shelf of the Laptev and other East-Arctic Seas of Russia has increased recently due their tremendous hydrocarbon potential and associated economic value, greenhouse gas emission and global warming, Northern Sea Route, and coastal erosion among
AC C
others (Grigoryev et al., 2006; Shakhova et al., 2010; Charkin et al., 2011; Vinogradov et al., 2013; Semiletov et al., 2013; Shakhova et al., 2015). In addition, this region is well suited for the detailed study of paleoclimatic changes and paleogeographical reconstruction due to the optimum preservation of organic remains in the permafrost and alternation of subaqueous and subaerial conditions caused by glacio-eustatic sea-level variations (Romanovskii et al., 2005). The latter are considered responsible for the origin of the rock ice complex and underlying sandy deposits (Bolshiyanov et al., 2007, 2008). The subsea permafrost, widespread in the near-shore shelf zone of the Laptev Sea and other Arctic seas is now under study (Grigoryev and Razumov, 2005; Grigoryev, 2008; Shakhova et al., 2017). The researchers of the Department of Geocryology of the Lomonosov Moscow State University (Romanovskiy and Tumskoy, 2011) indicated the possible
ACCEPTED MANUSCRIPT
existence of a 600–900 m thick permafrost with a complicated multilayer structure. The subsea permafrost of the eastern part of the Russian arctic shelf has been poorly studied due to technical difficulties and risks. The drilling of sea ice in the Sannikov and Dmitriy Laptev Straits allowed geologists of the “Sevmorgeo” and ”VNIIOkeangeologia“ to obtain the information on the shelf’s cryolite zone. Investigations showed that both permafrost and salinised frozen sediments existed in the shelf near-shore zone, though the bottom of the permafrost and cryolite zone have not been
RI PT
stripped as a whole. The most important data on the formation of the sands and ice complex have been obtained from drilling holes on the Laptev Sea shelf in the area of Mamontov Klyk Cape to the west of the Lena River delta (Fig. 1). The marine deposits at a depth of 58 m in Hole C-2 were characterised by diatom marine assemblage, remains of marine mollusk shells and contained marine
SC
pore water with salinities reaching 30 ‰. Evidence of sea deposits such as crushed bivalves, shell
detritus, and barrows were found near Hole C-1 bottom drilled on the shore, highlighting the basin
M AN U
conditions at the time of sedimentation (Bolshiyanov et al., 2007; Rachold et al., 2007; Winterfeld et al., 2011).
In 2011, the first Russian-American expedition conducted scientific drilling of the bottom sediments and permafrost in the near-shore zone in the south-eastern part of Laptev Sea (western part of the Buor-Khaya Bay to the east of Lena River delta). Drilling was conducted from the sea ice under the guidance of I. Semiletov (POI FEB RAS). The main task of the expedition was to drill
TE D
deep holes (up to 100 m) on the shelf to determine the methane potential, that is, the methane amount that may enter the atmosphere from the bottom deposits in the event of further warming and ice destruction in the Arctic. Simultaneously, the composition and structure of the deposits were studied (Sergienko et al., 2012). Subsequently the drilling program was prolonged, investigation
EP
was mostly directed to understand the thermal regime of sea water and subsea permafrost in the East Siberian Arctic Shelf coastal area, a simulation of the warming effect of sea water on subsea
AC C
permafrost integrity, origin of methane and current rates and mechanisms of subsea permafrost degradation of the area (Shakhova et al., 2013; Sapart et al., 2017; Shakhova et al., 2017). Our work aims to acquire new data on the micropaleontological composition of Laptev Sea shelf sediments obtained on these expeditions, to assess their age, genesis, and conditions of sedimentation.
2. Geological characteristics of the study area The Laptev Sea is a shallow epicontinental sea bordered by the Taymyr Peninsula to the west and New Siberian Islands to the east. The sedimentary cover is formed by the Cretaceous-Cenozoic complex underlain by the folded Late Kimmerian (Pre-Aptian) basement (Piskarev et al., 2003; Andieva, 2008; Malyshev et al., 2010). This complex is subdivided into four strata. The Upper Cretaceous stratum (400–3500 m thick) is composed exceptionally of continental coal-bearing
ACCEPTED MANUSCRIPT
molasse. The Paleogene - Lower Miocene stratum (600–5500 m thick) is formed by the alternation of sandstones, siltstones, mudstones, and rarely with interbeds of limestone and diatomites. It is terrigenous, with the development marine facies in the central part of the basin. The MiddleMiocene Pliocene (200–1300 m thick) and Quaternary (175–500 m thick) strata, separated by stratigraphic unconformity, are analogous to the Paleogene - Lower Miocene stratum in the
estimated at 8 to 12 km (Malyshev et al., 2010).
RI PT
lithological composition. The total thickness of the sedimentary cover of the Laptev Sea is
Permafrost with thickness between 400–600 m is widespread on the adjacent land (Derevyagin et al., 2013). The visible thickness of the Late Pleistocene sediments, composed predominantly of ice complex rocks, reaches 40 m (Kaplina, 2009). The ice complex overlaps the complicated relief
SC
and existed before its accumulation; this is evidenced by the same age of the ice complex strata, established by radiocarbon dating of different hypsometric levels of the ice complex. Its uppermost
M AN U
layers were accumulated under conditions of distinctly continental arid climate with tundra-steppe vegetation and very cold winters. The thickness of the Holocene deposits, dominated by sandy loams with lenses and interbeds of peat, usually does not exceed 4–5 m. 3. Material and methods
Holes 1D-11 and 4D-12 were drilled in the western part of the Buor-Khaya Bay (Fig. 1; Table
AC C
EP
TE D
1) to the east of the Lena River delta in the Laptev Sea in 2011 and 2012, respectively.
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 1. Location of the studied Holes (empty circles) and the Holes from Bolshiyanov et al.,
AC C
2007; Rachold et al., 2007; Winterfeld et al., 2011 (red circles). The red line denotes the location of high-resolution seismo-acoustic profile (illustrated in Fig. 2).
Table 1. Information on Holes examined in this study Hole
Longitude E
Latitude N
1D-11 4D-12
130°22,02' 129°52,524'
71°41,58' 71°37,758'
Water depth, m 11 10
Core length, m 52.3 55.8
Year of drilling 2011 2012
High-resolution seismo-acoustic investigations were conducted using a towed high-frequency “GeoPulse Subbottom Profiler” profilograph produced by GeoAcoustics Company. The
ACCEPTED MANUSCRIPT
investigations were conducted in 2008 on board the hydrographic ship “Yakov Smirnitskiy” as a part of “The International Siberian Shelf Study 2008 (ISSS-08)” Project and on the 57th voyage of the RV “Academic M.A. Lavrentyev” in 2011. Signals with 3.5 kHz frequency were used and data were registered in the 3 to 5 kHz frequency interval. The ship’s speed was 5–6 knots. The interval between emissions was 50 mc, which corresponded to a pitch of 13–15 cm. For micropaleontological analysis, 45 samples from Hole 1D-11 and 74 samples from Hole 4D-
RI PT
12 were acquired from all lithological types of sediments. width cm. For spore-pollen analysis 30 g samples were prepared using standard methods (Rudaya, 2010) including boiling samples in 10% KOH solution followed by washing with distilled water. Pollen and spore enrichment was performed using potassium-cadmium (KJ + CdJ2) heavy liquid with a density of 2.3 g/cm3. Diatom
SC
analysis included several steps. To determine diatom content per 1 g of air-dried sediment, 5 g samples were boiled, the sediment was diluted to 100 ml and mixed thoroughly; 0.2 ml of the
M AN U
suspension was used to prepare the slides for counting. To determine the qualitative composition of diatoms, the remainder of the sediment was again boiled with the addition of sodium tripolyphosphate and then washed. Due to the low diatom content all samples were treated with potassium-cadmium (KJ + CdJ2) heavy liquid with a density of 2.6 g/cm3 (Jousé et al., 1974). The slides were prepared using NORLAND synthetic resin with a refractive index of 1.56. The microfossils were studied and photographed using Mikmed-6 and IMAGER.Al light microscopes.
TE D
Spore-pollen nomenclature bases on Pokrovskaya (1966), diatom nomenclature revision follows AlgaeBase (Guiry M., Guiry G., 2018). 4. Results 4.1 Hole 1D-11
EP
High-resolution seismic profiles highlight that the sedimentary cover had a two-layer structure (Fig. 2). The upper layer was formed by acoustically transparent layers that were 2–6 m thick, and
AC C
contained rare, disordered, and short reflections about 10 m long. Generally, the thickness of the upper layer increased north eastwards to the deepest part of the sea. The top of the lower layer was represented by numerous highly intensive reflections, which were 10–150 m in length, and subparallel to the sea bottom. The depth of these reflections was not constant and varied from 2 to 6 m, which resulted in a peculiar saw-like profile of this layer’s upper part. Generally, the acoustic appearance of the lower layer was constant and characterised by the availability of chaotic reflections of different intensities, wherein stratification was absent.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 2. Fragment of the high-resolution seismo-acoustic profile illustrating structure of the upper part of the sediments in the area of Hole 1D-11, Buor-Khaya Bay, Laptev Sea.
A correlation of the seismoacoustic profile with the geological section of Hole 1D-11 (Fig. 3)
TE D
showed that the upper acoustically transparent layer corresponded to the Holocene clayey silt. At the drilling point, the thickness of the clayey silt was 5.5 m, which approximately coincided with our estimation of the thickness of the upper transparent layer (6 m). The lower stratum,
EP
characterised by chaotic reflections, corresponded to the sand layer of the Pleistocene age, containing dense dehydrated silt (DDS) that were about 1.5 m thick. At the point of drilling, the first layer of DDS occurred at a depth of 5.7 m, i.e. in the uppermost part of the sandy formation.
AC C
Thus, the highly intensive reflections, marking the position of the lower layer top, could have been formed at the boundary between the clayey silt of the upper layer and sand of the lower layer or due to the availability of DDS in the sand layer. Thus, the boundary between these layers on the seismoacoustic profile can have a complicated nature. However, based on the complicated saw-like picture of the lower layer top, it may be suggested that this feature is, most likely, a result of migration of the cryogene formations. Therefore, on the seismoacoustic profile, the boundary between the strata most likely corresponds to the top relief of DDS in the Holocene - Pleistocene sediments.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 3. Lithology of Hole 1D-11. 1 - fine sand – coarse sand, 2 - fine sand, 3 - silty sand, 4 – clayey sand, 5 - sandy silt, 6 – dense dehydrated silt (DDS), 7 - clayey silt, 8 – clay, 9 – silty clay; Inclusions: 10 - gravel and pebble, 11 - plant detritus (fragments); Texture: 12 - layered, 13 lenticular; Other symbols:14 - lost horizon of the core, 15 - position of acoustic boundaries on the high resolution seismo-section, 16 - samples taken for micropaleontological analysis, 17 – subsea permafrost. 4.1.1 Diatom analysis Diatoms were predominantly found in the upper part of the core in the 75–77 cm, 250-252 cm, 330-332 cm, and 415-417 cm intervals composed of clayey silt. Diatom concentration varies from 1700 to 14730 valves per gram of air-dried sediment, while in surface sediments of this region
ACCEPTED MANUSCRIPT
diatoms were relatively abundant (250-800 thousand valves/g) (Obrezkova et al., 2014; Tsoy and Obrezkova, 2017). Diatoms are represented by 73 species and intraspecific taxa belonging to 35 genera (Table 2; Plates 1-3). The genera richest in species and intraspecific taxa are Pinnularia (6 taxa), Gomphonema (6), Navicula (5), Cymbella (5), Aulacoseira (5), Thalassiosira (3), Stauroneis (3), Placoneis (3), Eunotia (3), Tabellaria (2), Epithemia (2), Encyonema (2), Diploneis (2), Diatoma (2), Amphora (2), and Alveolophora (2). Other genera are represented by single species.
RI PT
Most species are freshwater (60 taxa), 12 species are marine and brackish water, and 1 species is
AC C
EP
TE D
M AN U
SC
known from both fresh and marine waters.
Plate 1. Freshwater (1-10, 12, 13) and marine diatoms recovered from Hole 1D-11, BuorKhaya Bay, Laptev Sea. 1 – Cymbella cymbiformis C. Agardh; 2 – Cymbella cymbiformis var. nonpunctata Fontel; 3 – Amphora ovalis (Kützing) Kützing; 4 – Epithemia adnata (Kützing) Brebisson; 5 – Epithemia sorex Kützing; 6 – Eunotia bidens Ehrenberg; 7 – Eunotia praerupta Ehrenberg; 8 – Eunotia siberica Cleve; 9 – Cymbopleura inaequalis (Ehrenberg) Krammer; 10 –
ACCEPTED MANUSCRIPT
Placoneis amphibola (Cleve) E.J.Cox; 11 – Navicula valida Cleve & Grunow; 12 – Diploneis ovalis (Hilse) Cleve; 13 – Cocconeis placentula var. lineata (Ehrenberg) Van Heurck.
AC C
EP
TE D
M AN U
SC
RI PT
1, 2, 4-7, 9-13 (330-332 cm); 3 (250-252 cm); 8 – (75-77 cm). Scale bar 10 µ
Plate 2. Freshwater diatoms recovered from Hole 1D-11, Buor-Khaya Bay, Laptev Sea. 1,2 – Pinnularia viridis (Nitzsch) Ehrenberg; 3 – Pinnularia crucifera Cleve-Euler; 4 – Hantzschia amphioxys (Ehrenberg) Grunow; 5 – Craticula cuspidata (Kutzing) D.G.Mann; 6 – Stauroneis phoenicenteron (Nitzsch) Ehrenberg; 7, 8 – Caloneis silicula (Ehrenberg) Cleve; 9, 10 – Gomphonema olivaceum (Hornemann) Brébisson; 10 – Gomphonema brebissonii Kützing; 11 – Gomphonema truncatum Ehrenberg. 2, 8, 9 (250-252 cm); 1, 3-7, 11, 12 (330-332 cm); 10 (415-417 cm). Scale bar 10 µ Diatom assemblages from the 75–77 cm, 250-252 cm, 330-332 cm, and 415-417 cm intervals are dominated by fresh-water species Aulacosei ra subarctica (Müller) Harworth (14-39% of total
ACCEPTED MANUSCRIPT
number) and marine brackishwater species Thalassiosira baltica (Grunow) Ostenfeld (11-33%) (Plate 1). Other species are mostly represented by single occurrences or are extremely rare (Table 2). In some intervals freshwater species Alveolophora jouseana (Moiseeva) Moiseeva and A.
EP
TE D
M AN U
SC
RI PT
robusta (Khursevich) Usoltseva & Khursevich, which became extinct in the Miocene, were found.
Plate 3. Diatoms recovered from Hole 1D-11, Buor-Khaya Bay, Laptev Sea. 1-3 – Aulacoseira subarctica (Müller) Harworth; 4, 5 – Thalassiosira baltica (Grunow) Ostenfeld; 6 – Rhizosolenia
AC C
hebetata Bailey; 7, 8 – Thalassiosira hyperborea (Grunow) Hasle; 9 – Didymosphenia geminata (Lyngbye) Schmidt; 10 – Lindavia costata (L.P. Loginova, E.G. Lupikina & G.K. Khursevich) T. Nakov et al.; 11 – Aulacoseira praegranulata (Jousé) Simonsen; 12, 13 – Alveolophora jouseana (Moiseeva) Moiseeva; 14-17 – Alveolophora robusta (Khursevich) Usoltseva & Khursevich; 18, 19 – Paralia crenulata (Grunow) Gleser; 20 – Paralia grunowii Gleser. 1-10 – recent. 11-20 – extinct species. 1-3, 9-17 – freshwater, 4-8, 18-20 – marine diatoms. 1, 2, 5, 6, 8, 14-17 (330-332 cm); 3, 10 (75-77 cm); 4, 7, 9, 11 (250-252 cm interval); 12, 13 (415-417 cm); 18-20 (4130-4132 cm. Scale bar 10 µ
ACCEPTED MANUSCRIPT ecology
Table 2. List of diatom taxa and their number in samples of the core of Hole 1D-11. Taxa
Interval, cm 7577
250252
Alveolophora jouseana (Moiseeva) Moiseeva in Moiseeva & Nevretdinova A. robusta (Khursevich) Usoltseva & Khursevich
fw,ex
Amphora libyca Ehrenberg
m
A. ovalis (Kützing) Kützing Aulacoseira ambigua (Grunow) Simonsen
fw fw
2
A. granulata (Ehrenberg) Simonsen
fw
3
A. islandica (Müller) Simonsen
fw
2
A. praegranulata (Jousé) Simonsen
fw,ex
2
3
A. subarctica (Müller) Harworth
fw
18
14
Caloneis silicula (Ehrenberg) Cleve
fw
Cocconeis placentula var. lineata (Ehrenberg) Van Heurck
fw
Coscinodiscus oculus iridis Ehrenberg
m
C. sibiricus Strelnikova? Craticula cuspidata (Kutzing) D.G.Mann
m, ex
Cymbella cf. arctica (Lagerstedt) Schmidt C. cistula (Ehrenberg) O.Kirchner C. cymbiformis C.Agardh C. cymbiformis var. nonpunctata Fontel Cymbella sp.
3
2
27702772
35303532
41304132
1
1 2
2
1
fw fw
1
2
2
15
SC
1
1
1 1 1
fw
1
Diatoma mesodon (Ehrenberg) Kűtzing Diatoma vulgaris Bory
Didymosphenia geminata (Lyngbye) Schmidt
fw
Diploneis ovalis (Hilse) Cleve
fw
1
fw
1
fw
1
TE D
2
1
fw
EP
*
1
fw
1
1 1
1
1 2
1
Encyonema elginense (Krammer) Mann E. silesiacum (Bleish) D. Mann.
fw
2
Epithemia adnata (Kützing) Brebisson
fw
4
E. sorex Kützing
fw
1
1
Eunotia bidens Ehrenberg
fw
1
1
E. praerupta Ehrenberg
fw
4
E. siberica Cleve
fw
1
Fragilaria capucina Desmazières
m/fw
Gladiopsis speciosus (Schulz) Gersonde et Harwood
m, ex
Gomphonema affine Kützing
fw
G. brebissonii Kützing
fw
2
G. olivaceum (Hornemann) Brébisson Gomphonema spp.
fw
1
fw
4
G. truncatum Ehrenberg
fw
1
G. ventricosum W.Gregory
fw
1
AC C
*
2
fw fw
40
1
fw
bw
2
RI PT
2
1 1
fw
1 1
Cymbopleura inaequalis (Ehrenberg) Krammer
Diploneis sp.
415417 1
fw,ex
M AN U
Cyclotella striata (Kützing) Grunow)
330332
1
1
1
1
4
4
1
1
5
5
3
1 *
1
1
2 1 2
ACCEPTED MANUSCRIPT
Hannaea arcus (Ehrenberg) R.M.Patrick Hantzschia amphioxys (Ehrenberg) Grunow
fw
Melosira arctica (Ehrenberg) Dickie Meridion circulare (Greville) Agardh
m m
Navicula digitoradiata (Gregory) Ralfs
m
N. impexa Hustedt
fw
N. radiosa Kützing
fw
Navicula sp.
fw
N. valida Cleve & Grunow
m
Nitzschia sigma (Kützing) W.Smith
bw
Odontidium hyemale (Roth) Kützing
fw
Paralia crenulata (Grunow) Gleser
7577
330332
P. sulcata (Ehrenberg) Cleve Pinnularia crucifera Cleve-Euler
1
fw
P. major (Kützing) Rabenhorst P. stomatophora Grunow P. streptoraphe Cleve
2
1
1
1
1
1
1
1
1
1
2
P. gastrum (Ehrenberg) Mereschkowsky
fw
P. placentula (Ehrenberg) Heinzerling
fw
1
Rhizosolenia hebetata Bailey
m
1
1
1
1
1
1
3
1 1 1
fw
1
3
fw
S. laevissima (Kützing) D.G.Mann
fw
1
Stauroneis anceps Ehrenberg
fw
1
S. phoenicenteron (Nitzsch) Ehrenberg
fw
2
2
Stauroneis siberica (Grunow) Lange-Bertalot & Krammer Tabellaria fenestrata (Lyngbye) Kützing
fw 3
2
Tabellaria flocculosa (Roth) Kűtzing Thalassiosira baltica (Grunow) Ostenfeld
fw m, bw m
AC C
Sellaphora bacillum (Ehrenberg) D.G.Mann
Thalassiosira constricta Gaarder Thalassiosira hyperborea (Grunow) Hasle Ulnaria ulna (Nitzsch) P.Compère
*
1
1
2
*
*
1
fw
EP
1
1
Placoneis amphibola (Cleve) E.J.Cox
Rhopalodia gibba (Ehrenberg) O. Müller
41304132
1
fw
fw
35303532
1
fw
TE D
P. viridis (Nitzsch) Ehrenberg
27702772
4
fw
P. episcopalis Cleve
415417
1
fw
m, ex m, ex m, bw fw
250252
M AN U
P. grunowii Gleser
Interval, cm
SC
Taxa
RI PT
ecology
Table 2. Continued.
1
1 fw
m, bw fw
2
3
1 8
26
23
16
1 4
2
3
1
1
1
1
4
Total number in a slide
25
38
56
36
Number of taxa recognized
30
25
53
30
1
1
Notes: Acronyms for ecological characteristics of diatoms: fw – freshwater, bw – brackishwater, m – marine, ex – extinct diatoms; * - sporadically occurred diatoms.
4
ACCEPTED MANUSCRIPT
The latter species has been recently identified in the Middle-Late Miocene lake deposits of the Vitim Highland (Usoltseva and Khursevich, 2013) surrounded by the Vitim River, the right tributary of the Lena River. Due to the abrasion of the Miocene lake sediments, this species arrived with the tributary waters of the Lena River into the sediments of the Buor-Khaya Bay. Marine brackish-water species Thalassiosira hyperborea (Grunow) Hasle, T. constricta Gaarder, Cyclotella striata (Kützing) Grunow, and Melosira arctica (Ehrenberg) Dickie occurred with a single
RI PT
specimen. The latter is a typical arctic species that vegetates in sea ice. The oceanic cold-water species Rhizosolenia hebetata Bailey was also found in 75-77 and 330-332 intervals.
Diatoms were not found in the 560–3532 cm interval, except in the 2770–2772 cm interval, where the tychopelagic species Paralia sulcata (Ehrenberg) Cleve that is characteristic of low
Coscinodiscus oculus iridis Ehrenberg was found.
SC
salinity sea waters was noted; and the 3530–3532 cm interval, where the planktonic oceanic species
M AN U
In the 4130–4132 cm interval, half-dissolved indefinable valves of diatoms as well as isolated diatoms represented by marine extinct species Paralia grunowii Gleser and P. crenulata (Grunow) Gleser (Plate 3), fragments of species that look like Gladiopsis speciosus (Schulz) Gersonde & Harwood, and Coscinodiscus sibiricus Strelnikova were found. The Paralia grunowii Gleser has been known from the Cretaceous, P. crenulata (Grunow) Gleser species is typical of the Late Cretaceous-Paleogene deposits, and Gladiopsis speciosus (Schulz) Gersonde & Harwood and
TE D
Coscinodiscus sibiricus Strelnikova species are restricted to the Late Cretaceous. These species are common in the Cretaceous deposits of the East Urals (Strelnikova, 1974), the Paleogene of the West Siberia, and Lomonosov Ridge of the Central Arctic (Kim and Glezer, 2007), Campanian deposits of the Upper Cretaceous of the Arctic Archipelago, and the Horton River section of the
EP
northwestern coast of Canada (Tapia and Harwood, 2002). It is suggested that the species found in the 4130–4132 cm interval were redeposited. In the study area of Laptev Sea, Cretaceous deposits
AC C
are essentially continental, implying that the sources of the extinct marine species of diatoms are probably Cretaceous and Paleogene marine deposits widespread in the Arctic region. Below, in the 4220–5232cm interval, diatoms were not found; only isolated spicules of sponges were noted in the 4320–4330 cm interval.
Thus, the diatoms found in the clayey silt of the upper part (interval 0–417 cm) of Hole 1D-11, are common in the modern and Holocene sediments at the mouth of the Lena River in Laptev Sea (Polyakova, 1997; Cremer, 1999; Bauch and Polyakova, 2000; Tsoy, 2001; Matul et al., 2007; Obrezkova and Tsoy, 2008; Obrezkova et al., 2014). They are characterised by the predominance of fresh-water diatoms, supplied by the Lena River run-off, and insignificant amount of marine brackish-water species, as well as the presence of redeposited fresh-water species that became extinct in the Miocene. Below, in the 560–5232 cm interval, diatoms were practically inexistent
ACCEPTED MANUSCRIPT
with the exception of 2770–2772 cm and 3530–3532 cm intervals where isolated marine species have been noted. The fossilised marine species of diatoms, found in the 4130–4132 cm interval, are typical of Cretaceous-Paleogene deposits of the Arctic region and are, most likely, redeposited. Vegetal detritus and coaly particles were found in all the examined samples and are typical of Laptev Sea sediments (Holmes and Creager, 1974). 4.1.2 Spore-pollen analysis
RI PT
In the upper part of the sedimentary cover (interval 0–417 cm, clayey silt) a group of wood species comprising 48–70 % was identified. They were characterised by the predominance of Pinus pollen (chiefly Pinus pumila - 32-51 %; Pinus silvestris - 8-22 %), followed by pollen of the Betulaceae family (22-44 %), which were essentially of the shrubs Betula and Alnaster.
SC
Concentration of pollen of dark conifers species varies from 3–15 % (Table 3, Fig. 4).
Table 3. Percentage of the pollen and spores in Hole 1D-11 Pollen of
wood
grasses and
species
shrubs
0–417
48–70
2-15
24-56
670–772
50-56
11-17
32-33
880–882
70
10
20
2240–2242
72
4
23
cm
Spores
Pollen of dark
Pollen
Pollen Pinus
Pollen of
conifers
Pinus
silvestris
Betulaceae
species
pumila
3-15
32-51
8-22
22-44
3-4
20-22
6-7
68-69
10
37
13
40
49
24
21
4
M AN U
Pollen of
TE D
Intervals,
family
Grasses and shrubs constituted 2-15 %; pollen grains of Ericales, Asteraceae, Caryophyllaceae, and others were present. Cryptogamic plants (24-56 %) were mostly represented by the spores of
EP
the Polypodiaceae, Sphagnum family; spores of Bryales, Lycopodium were found in lesser amount. The spore-pollen spectrum reflects the composition of the current flora found in north of East
AC C
Siberia. Naidina (2009) and Savelyeva et al. (2011) noted the understated representation of cryptogamic plants, which are common in the tundra zone and often dominate the plant cover. It is suggested that sediments containing the above spore-pollen complex, were formed in the Holocene. Redeposited pollen grain samples of Lycopodium, Ophyoglossaceae, Osmunda, Schizeaceae?, Podocarpus?, Tsuga, Picea, Abies, Pinus, Juglans, Pterocarya, Ulmus, Syringa?, and Tilia were also found.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 4. Spore-pollen diagram of Hole 1D-11 upper part, Buor-Khaya Bay, Laptev Sea. AP -
TE D
pollen of trees; NAP - pollen of shrubs and grasses; SP - spores.
In the 670–780 cm interval (670–672 cm - silt, 770–772 cm - fine sand), a group of wood
EP
species pollen (50–56 %) including the Betulaceae family (68-69 %) bush birches, and alders (Duschekia fruticosa Alnaster) were dominant. Among the Pinus pollen, P. pumila constituted 2022 % and P. silvestris constituted 6-7 %. Dark conifers pollen accounted for 3-4 %. In the group of
AC C
grasses and shrubs, pollen grains of Ericales, Asteraceae, Umbelliferae, Campanulaceae, and others were found. The spectrum composition was similar to the palinospectra characteristic of Early Holocene of the Arctic eastern sector, reflecting the vegetation of the Arctic tundra (Naidina, 2011). The increased content of the Betula pollen in the spectrum may indicate relatively warm climatic conditions (Naidina, 2009). Most part of the Arctic shelf shows depths of less than 100 m and has formed over the past last 11.7 thousand years (Naidina, 2011). Possible presence of the Lena River delta located somewhat to the north during the Pre-Holocene era, can explain the low or nonexistent quantities of pollen at below 770–772 cm level as conditions favouring its accumulation were poor. In the 880–882 cm interval (silt), microfossils in the spectrum were few in number, but the pollen of wood species dominated (70 %), represented chiefly by Pinus (Pinus pumila - 37 %;
ACCEPTED MANUSCRIPT
Pinus silvestris - 13 %); pollen of small-leaf species of the Betulaceae family was lower (40 %). The pollen of dark-needle conifers constituted 10 %, mainly comprising of Picea and more rarely Abies pollen. The pollen of grasses and shrubs was little, amounting to 10 % (including Asteraceae, Cyperaceae, Onagraceae, Ericales, and others). Cryptogamic plants (20 %) were mainly represented by Polypodiaceae, Sphagnum, and to a lesser extent by Lycopodium and Bryales. Redeposited pollen grains of Picea, Pinus, Juglans, and Quercus were also found.
RI PT
In the 2240–2242 cm interval (silty sand), the pollen level was very little and amounted to around 111 pollen grains per specimen. However, a conventional spore-pollen spectrum was distinguished, which was dominated by the pollen of trees (72 %) (Table 2, Fig. 4). Dark-needle species, particularly Picea, accounting for 49 %, were predominant. Pinus pollen amounted to 32 %
SC
of the Pinus sect. Cembrae pollen (including P. sibirica and P. Pumila) constituted 24 %, and the Pinus sect. Eupitys (Pinus silvestris) pollen accounted for nearly 21 %. Pollen of small-leaved
M AN U
species of the Betulaceae family and grasses were isolated. Cryptogamic plants (23 %) were represented by Osmunda, Lycopodium, Sphagnum, Polypodiaceae, and others. Isolated redeposited spores of Lygodium? and isolated pollen grains of Abies were noted.
The depleted palinospectrum established for this interval was dominated by the pollen of darkneedle species and is typical of Pleistocene deposits. The presence of redeposited spores and pollen of the Tertiary age is common in the Quaternary sediments (Derevyanko and Gusev, 2011) and
TE D
testifies to the erosion and degradation of the Paleogene and Neogene strata widespread on the Arctic shelf of Russia and adjacent land.
In the sediments of the lower part of Hole 1D-11 (interval 2770–5100 cm), represented mainly by silty sand, pollen and spores were absent or in insignificant quantities. The microfossils were
EP
strongly mineralised, but their composition (Pinus, Picea, and Betulaceae family) conditionally allows us to suggest Pleistocene age of the sediments.
AC C
The micropaleontological study of the sediments of the eastern part of the Lena River delta, stripped by Hole 1D-11, suggests that the sediments in the upper 772 cm were probably formed in the Holocene under transgressive conditions with significant influence of the Lena River flow and Arctic tundra vegetation on the shore; those in the lower 772–5230 cm were formed in the Pleistocene, predominantly under continental conditions.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
TE D
Plate 4. Spores and pollen from core of Hole 1D-11, Buor-Khaya Bay, Laptev Sea. Spores: 1 – Polypodiaceae; 2, 3 – Lycopodium sp.; 4 – Bryales; 5-6 – Sphagnum sp. Pollen: 7 – Picea sect. Eupicea; 8 – Picea sect. Omorica; 9-11 – Pinus silvestris L.; 12, 13 – Pinus sect. Cembrae; 14, 15 – Betula sect. Albae; 16 – B. exilis Sukacz.; 17, 18 – B. middendorffii Trautv. et Mey; 19-22 – Alnus
EP
sp.; 23-26 – Alnaster (Dushekia) sp.; 27, 28 – Salix sp.; 29 – Compositae; 30 – Artemisia sp.; 31 –
AC C
Ericales; 32 – Cariophyllaceae. 1-32 (75-77 cm interval). Scale bar 20 µ
4.2 Hole 4D-12
Hole 4D-12 was drilled to the northwest of Muostakh Island to a depth of about 10 m and 55.8 m thick sediments were collected. They were mostly composed of the clayey silt of different densities and sand (Fig. 5). Diatoms were not found over the entire column length, redeposited pollen and spores occurred sporadically. Redepositions were found at 115–117 cm level and included Lycopodium, Picea sp., Pinus sect., Cembrae, Pinus sect. Eupitys, and Ericales, which were not likely to be older than the Pleistocene. Isolated pollen grains of Podocarpus, Dacridium, and Tsuga and ancient spores belonging to the Schizaceae Family, supposedly of the Paleogene age, were found down the column. Due to very low content to total absence of microfossils in the Hole
ACCEPTED MANUSCRIPT
4D-12, the column can be rather conditionally divided into two intervals: Holocene from 0–120 cm
AC C
EP
TE D
M AN U
SC
RI PT
and Pleistocene from 120–4420 cm. Further identification of detailed subdivisions was not possible.
Fig. 5. Lithology of Hole 4D-13. Lithologic and other symbols are explained on Figure 3.
5. Discussion
ACCEPTED MANUSCRIPT
We observed that microfossils were rare in the in the lower part (560–5232 cm interval) of the shelf zone sediments of the Buor-Khaya Bay (Laptev Sea) represented mostly by silty sand, stripped by Hole 1D-11 (in 2011). Diatoms were practically not found, with the exception of 2770– 2772 cm and 3530–3532 cm intervals where isolated marine species have been noted. The fossilised marine species of the diatoms, found in the 4130–4132 cm interval, are typical to the CretaceousPaleogene deposits of the Arctic region and are, most likely, transported and redeposited from there.
RI PT
Spores and pollen in this part of the Hole were isolated or absent, with the exception of 880– 882 cm and 2240–2242 cm intervals where the depleted palinospectra were dominated by the pollen of wood species such as dark-needle conifers and birch, and isolated redeposited spores and pollen were observed. The composition (Pinus, Picea, fam. Betulaceae) suggests somewhat conditionally
SC
Pleistocene age of the sediments.
The sediments of the upper part (0–417 cm) of the Hole contained diatoms that are common in
M AN U
the modern sediments of the Lena River delta of the Laptev Sea; they were probably formed under close conditions. They were characterised by the predominance of fresh-water diatoms supplied by the Lena River run-off, an insignificant amount of coastal-marine species, and the presence of the redeposited fresh-water species that became extinct in the Miocene.
The spore-pollen spectrum from the sediments of this interval reflects the composition of vegetation that can be currently found in the north of East Siberia and is typical to Holocene
TE D
sediments of this region (Rudenko et al., 2014). The formation of marine spore-pollen spectra is simultaneously influenced by several factors such as wind scattering, river flows, and abrasion of banks (Naidina, 2009). The Lena River run-off played an important role by transporting significant amount of sediments into the sea in the form of very fine particles (including plant pollen), which
EP
accumulated on the shelf. The modern flora of the Laptev Sea coast is characterised by forest-free landscapes. The pollen of trees, shrubs, and grasses is abundant in the marine deposits of the upper
AC C
part of Hole 1D-11 and appear to reflect the vegetation of nearby shores as well as the regional vegetation of Yakutia (Naidina, 2011). Big rivers can supply pollen and spores to distances up to 4000 km (Sladkov, 1967). The detection of palinospectra of the pollen of Picea, Abies, and Pinus silvestris, whose area is far to the south, may be explained by cyclones and winds blowing predominantly from southwest to northeast (Naidina et al., 2000; Naidina, 2009). However, it is possible that the initial stage of the Holocene began earlier, in the 770–772 cm interval, as the spore-pollen spectrum characterizes the beginning of the Holocene of the Arctic eastern sector, reflecting the vegetation of the Arctic tundra. However, the low content of diatoms, spores, and pollen in the Holocene-Pleistocene sediments of the eastern part of the Lena River delta, stripped by the Holes, rendered it impossible to distinguish detailed subdivisions.
ACCEPTED MANUSCRIPT
6. Conclusions
The micropaleontological (diatoms, palinoflora) study of the deposits, stripped by Holes 1D-11 and 4D-12, has established that the sedimentary section is subdivided into two different-age strata Late Pleistocene and Holocene that were formed under different conditions. The Pleistocene stratum, composed of different-grain sands containing cryogene inclusions about 1.5 m thick, was formed under continental conditions. The Holocene stratum, composed predominantly of clayey
RI PT
silt, was developed under transgressive conditions with significant influence of the Lena River runoff with vegetation of the Arctic tundra on the coast.
Acknowledgments
SC
The authors thank L.V. Osipova for the chemical-technical treatment of the samples for the micropaleontological analysis, I.V. Chervinskaya and N.S. Lee for the graphic works. We are
helped improve the manuscript. Funding:
This
research
was
M AN U
grateful to Dr. U.P. Vasilenko and one anonymous reviewer for their constructive comments that
supported
by
the
Russian
Government
(no.
14.Z50.31.0012/03.19.2014) and Russian Science Foundation (no. 16-17-10109).
TE D
References
Andieva, T.A., 2008. Tectonic position and major structures of the Laptev Sea / Petroleum Geology - Theoretical and Applied Studies. 3(1): 1-27. www.ngtp.ru. Bauch, H.A., Polyakova, Y.I., 2000. Late Holocene variations in Arctic shelf hydrology and sea-ice
569-577.
EP
regime: evidence from north of the Lena Delta. International Journal of Earth Sciences. 89:
AC C
Bolshiyanov, D.Y., Grigoryev, M.N., Shnaider, V., Rakhold, F., Overduin, P., Hubberten, H., Makarov, A.S., Gusev, E.A. 2007. Fluctuations of the sea level and formation of the rock ice complex on the coast of the Laptev Sea in the Late Neo-Pleistocene. Materials of the V AllRussia Meeting on the study of the Quaternary period. Moscow. GEOS: 45-49. Bolshiyanov, D.Y., Makarov, A.S., Gusev, E.A., Shanider, V. 2008. Problems of Ice Complex origination and former «Sannikovs Lands» existence in the Laptev Sea. Problems of the Arctic and Antarctic continents. 1(78): 151-160. Charkin, A. N., Dudarev, O. V., Semiletov, I. P., Kruhmalev, A. V., Vonk, J. E., Sánchez-García, L., Karlsson, E., Gustafsson, Ö. 2011. Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor-Khaya Gulf: the primary recipient of input from Lena
ACCEPTED MANUSCRIPT
River and coastal erosion in the southeast Laptev Sea, Biogeosciences, 8, 2581–2594, doi:10.5194/bg-8-2581-2011. Cremer, H. 1999. Distribution patterns of diatom surface sediment assemblages in the Laptev Sea (Arctic Ocean). Marine Micropaleontology. 38: 39-67. Derevyagin, A.Y., Chizhov, A.V., Maier, X., Opel, T., Schirrmeister, L., Wetterich, S. 2013. Isotopic composition of texture ices, Laptev sea coast. Earth`s Cryosphere. 17(3): 27-34.
RI PT
Derevyanko, L.G., Gusev, E.A. 2011. Redeposited spores and pollen in the Holocene sediments of the outer part of the Arctic shelf of Russia // Problems of the modern palinology: Materials of the XIII Russian Palinological Conference with the international participation (Syktyvkar, Komi Republic, September 5-8, 2011). Syktyvkar: IG of the Komi Scientific Center of the
SC
Urals Branch of RAS. II: 74-77.
Grigoryev, M.N. 2008. Cryomorphogenesis and lithodynamics of the coastal-shelf zone of the seas
M AN U
of the Eastern Siberia. Thesis of the Doctor of geographical sci. Yakutsk. pp.291. Grigoryev, M.N., Razumov, S.O. 2005. Distribution and evolution of the subaqual frozen ground in the coastal-shelf zone of the Laptev and East-Siberian Seas as a result of the many-year transformation of the coastal zone. Present geodynamics and dangerous natural processes in Central Asia. Irkutsk: Publishing House of the Institute of the Earth’s Crust, the Siberian Branch of RAS. 2: 136-155.
TE D
Grigoryev, M.N., Razumov, S.O., Kunitskiy, V.V., Spektor, V.B. 2006. Dynamics of the Russian East Arctic Sea coast: major factors, regularities and tendencies. Earth`s Cryosphere. X(4):7494. http://www.izdatgeo.ru.
Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National
EP
University of Ireland, Galway. http://www.algaebase.org. Holmes, M.L., Creager, Y.S. 1974. Holocene history of the Laptev Sea Continental Shelf. Marine
AC C
Geology and Oceanography of the Arctic Seas. 211-229. DOI 10.1007/978-3-642-87411-6_9. Jousé A.P., Proschkina-Lavrenko A.I., Ssheshukova-Poretskaya V.S. 1974. Method of research. In: Diatoms of the USSR Fossil and Recent. Vol. I, pp. 50–79. Nauka, Leningrad. Kaplina, T.N. 2009. Alas complex of north Yakutia. Earth`s Cryosphere. XIII(4): 3-17. Kim, B.I., Glezer, Z.I. 2007. Sedimentary cover of the Lomonosov Ridge: Stratigraphy, structure, deposition history, and ages of seismic facies units. Stratigraphy and Geological correlation. 15(4): 401-420. Malyshev, N.A., Obmetko, V.V., Borodulin, A.A. 2010. Evaluation of the oil-gas content of sedimentary basins of the East Arctic. Scientific-technical Bulletin of the OAO NK “Rosnefte”. 1:20-28.
ACCEPTED MANUSCRIPT
Matul, A.G., Khusid, T.A., Mukhina, V.V., Chekhovskaya, M.P., Safarova, S.A. 2007. Recent and Late Holocene environments on the southeastern shelf of the Laptev Sea as inferred from microfossil data. Oceanology. 47(1): 80-90. Naidina, O.D. 2009. Environmental changes in the eastern shelf of the Laptev Sea in the late-glacial time. Stratigraphy and Geological correlation. 17(5): 95-108. Naidina, O.D. 2011. Pollen “tells” … about the climate of the past. Science in Russia. 3: 54-60.
RI PT
Naidina, O.D., Baukh, H.A., Kassence, H. 2000. First data on the distribution of pollen and spores in the surface sediments of the Laptev Sea and their importance for the paleoclimatic reconstructions of the Holocene of the Arctic Siberia. Bulletin of Moscow Society of Naturalists. Geological Branch. 75(1): 67-72.
SC
Obrezkova, M.S., Kolesnik, A.N., Semiletov, I.P. 2014. The diatom distribution in the surface sediments of the Eastern Arctic Seas of Russia. Russian Journal of Marine Biology. 40(6): 465-
M AN U
472. DOI: 10.1134/S1063074014060170
Obrezkova, M.S., Tsoy, I.B. 2008. Diatom flora of the Holocene sediments of the Russian EastArctic seas. Bulletin of FEB RAS. 1:136-143.
Pokrovskaya, I.M. 1966 (Ed.). Paleopalynology, Nedra, Leningrad. Vol. 3. 368 pp. (in Russian). Piskarev, A.L., Soroka, I.V, Chernyshev, M.Y. 2003. Structure of the earth crust and tectogenesis in the Laptev Sea. Geotectonics. 3:57-72. (In Russian)
pp. 146.
TE D
Polyakova, E.I. 1997. Arctic seas of Eurasia in the Late Cenozoic time. Moscow: Scientific World.
Rachold, V., Bolshiyanov, D.Y., Grigoriev, M.N., Hubberten, H.W., Junker, R., Kunitsky, V.V., Merker, F., Overduin, P.P., Schneider, W. 2007. Near-shore Arctic subsea permafrost in
EP
transition. EOS: Transactions of the American Geophysical Union. 88(13): 149-156. Romanovskii, N., Hubberten, H., Gavrilov, A., Eliseeva, A., Tipenko, G. 2005. Offshore permafrost
AC C
and gas hydrate stability zone on the shelf of East Siberian Seas. Geo-Mar. Lett. 25: 167-182. doi:10.1007/s00367-004-0198-6 Romanovskiy, N.N., Tumskoy, V.E. 2011. Retrospective approach to the estimation of the contemporary extension and structure of the shelf cryolithozone in East Arctic. Earth`s Cryosphere. XV(1): 3-14. http://www.izdatgeo.ru. Rudaya, N.A. 2010. Palinological analysis: teaching-methodical manual. Novosibirsk State University, Institute of Archaeology and Ethnography, Siberian Branch of RAS. 48 p. Rudenko O., Tarasov P.E., Bauch H.A., Taldenkova E. 2014. Quaternary International 348; 82-92. http://dx.doi.org/10.1016/j.quaint.2014.04.032 Sapart C.J., Shakhova N., Semiletov I., Jansen J., Szidat S., Kosmach D., Dudarev O., van der Veen C., Egger M., Sergienko V., Salyuk A., Tumskoy V., Tison J.L., Rockmann T. 2017. The origin
ACCEPTED MANUSCRIPT
of methane in the East Siberian Arctic Shelf unravelled with triple isotope analysis. Biogeosciences. 14(9):2283-2292. doi: 10.5194/bg-14-2283-2017 Savelyeva, L.A., Morozova, E.A., Titova, D.V. 2011. Subfossil spore-pollen spectra and modern vegetation of the Lena River delta. Problems of the modern palinology: Materials of the XIII Russian Palinological Conference with the international participation (Syktyvkar, Komi Republic, September 5-8, 2011). Syktyvkar: IG of the Komi Scientific Center, Urals Branch of
RI PT
RAS. 1: 102-103.
Semiletov, I.P., Shakhova, N.E., Pipko, I.I., Pugach, S.P., Charkin, A.N., Dudarev, O.V., Kosmach, D.A., Nishino, S. 2013. Space-time dynamics of carbon and environmental parameters related to carbon dioxide emissions in the Buor-Khaya Bay of the Laptev Sea. Biogeosciences. 10:
SC
5977-5996, www.biogeosciences.net/10/5997/2013/doi:10.5194/bg-10-105977-2013.
Sergienko, V. I., Lobkovskii, L. I., Semiletov, I. P., Dudarev, O. V., Dmitrievskii, N. N., Shakhova,
M AN U
N. E., Romanovskii, N. N., Kosmach, D. A., Nikol’skii, D. N., Nikiforov, S. L., Salomatin, A. S., Anan’ev, R. A., Roslyakov, A. G., Salyuk, A. N., Karnaukh, V.V., Chernykh, D. B., Tumskoi, V. E., Yusupov, V. I., Kurilenko, A. V., Chuvilin, E. M., and Bukhanov, B. A. 2012. The Degradation of Submarine permafrost and the destruction of hydrates on the shelf of East Arctic Seas as a potential cause of the “Methane Catastrophe”: some results of integrated studies in 2011. Dokl. Earth Sci. 446: 1132–1137.
TE D
Shakhova N., Semiletov I., Gustafsson O., Sergienko V., Lobkovsky L., Dudarev O., Tumskoy T., Grigoriev M., Mazurov A., Salyuk A., Ananiev R., Koshurnikov A., Kosmach D., Charkin A., Dmitrevsky N., Karnaukh V., Gunar A., Meluzov A., Chernykh D. 2017. Current rates and mechanisms of subsea permafrost degradation in the East Siberian Arctic Shelf. Nature
EP
communications. doi: 10.1038/ncomms15872
Shakhova, N., Semiletov I., Leifer I., Sergienko V., Salyuk A., Kosmach D., Chernykh D., Stubbs
AC C
C., Nicolsky D., Tumskoy V., Gustafsson Ö. 2013. Ebullition and storm induced methane release from the East Siberian Arctic Shelf. Nature Geoscience, 7, doi: 0.1038/ NGEO2007 Shakhova, N., Semiletov, I., Salyuk, A., Yusupov, V., Kosmach, D., Gustafsson, O. 2010. Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf. Science. 327:1246-1250. doi:10.1126/science.1182221 Shakhova, N., Semiletov, I., Sergienko, V., Lobkovsky, L., Yusupov, V., Salyuk, A., Salomatin, A., Chernykh, D., Kosmach, D., Panteleev, G., Nicolsky, D., Samarkin, V., Joye, S., Charkin, A., Dudarev, O., Meluzov, A., Gustafsson, O. 2015. The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice. Philosophical. Transactions of the Royal Society. 373: 20140451. http://dx.doi.org/10.1098/rsta.2014.0451 Sladkov, A.N. 1967. Introduction to the spore-pollen analysis. Moscow: Nauka. pp 270.
ACCEPTED MANUSCRIPT
Strelnikova, N.I. 1974. Diatoms of the Late Cretaceous (West Siberia). Moscow: Nauka. pp 204. Tapia, P.M., Harwood, D.M. 2002. Upper Cretaceous diatom biostratigraphy of the Arctic archipelago and northern continental margin, Canada. Micropaleontology. 48(4): 303-342. Tsoy I.B., Obrezkova M.S. 2017. Atlas of diatom algae and silicoflagellates from Holocene sediments of the Russian East Arctic seas. Vladivostok: POI FEB RAS. 146 p. Tsoy, I.B. 2001. Diatoms in surface sediments of the Siberian Arctic shelf (Laptev and East-
Vladivostok: Dalnauka. pp. 245-249.
RI PT
Siberian seas). Changes in the Atmosphere-land-sea system in the Amerasian Arctic.
Usoltseva, M., Khursevich, G. 2013. Alveolophora robusta comb. nov. from Miocene deposits of the
Vitim
Plateau,
Russia.
Diatom
28(1):
109-114.
DOI:
SC
10.1080/0269249X.2012.738251
Research.
Vinogradov, V., Goryachev, Y., Suprunenko, O. 2013. Laptev Sea as a possible base of effective
M AN U
development of oil and gas resources of Russian Arctic shelf. Drilling and Oil. 2. http://burneft.ru/archive/issues/2013-02/3
Winterfeld, M., Schirrmeister, L., Grigoriev, M. N., Kunitsky, V. V., Andreev, A., Murray, A., Overduin, P. P. 2011, Coastal permafrost landscape development since the Late Pleistocene in
AC C
EP
TE D
the western Laptev Sea, Siberia. Boreas, 10.1111/j.1502-3885.2011.00203.x. ISSN 0300-9483.
S1040-6182(18)30126-5
DOI:
https://doi.org/10.1016/j.quaint.2018.10.033
Reference:
JQI 7609
To appear in:
Quaternary International
Received Date: 2 March 2018 Revised Date:
6 July 2018
Accepted Date: 23 October 2018
Please cite this article as: Obrezkova, M.S., Tsoy, I.B., Semiletov, I.P., Vagina, N.K., Karnaukh, V.N., Dudarev, O.V., Micropaleontological assessment of sediments from Buor-Khaya Bay (Laptev Sea), Quaternary International (2018), doi: https://doi.org/10.1016/j.quaint.2018.10.033. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Micropaleontological assessment of sediments from Buor-Khaya Bay (Laptev Sea) Obrezkova M.S.1*, Tsoy I.B.1, Semiletov I.P.1,2 , Vagina N.K.1, Karnaukh V.N.1, Dudarev O.V.1,2 1
V.I. Ilyichev Pacific Oceanological Institute Far Eastern Branch Russian Academy of Science (POI FEB RAS), Vladivostok, 690041 Russia Tomsk National Research Polytechnic University, Tomsk, 634050 Russia *e-mail: [email protected]
Abstract
RI PT
2
The paper presents the first set of micropaleontological data from the Buor-Khaya Bay
SC
sediments in the southeastern part of the Laptev Sea, obtained from the bottom sediments through permafrost drilling. The study of diatoms and spore-pollen assemblages in Hole 1D-11 and Hole 4D-12, high-resolution seismic profiling, and lithological composition of the sediments have
M AN U
facilitated the identification of two different age strata formed under different conditions and dating to the Late Pleistocene and Holocene. The Pleistocene strata were composed of assorted sands with inclusions of dense dehydrated silt formed under continental conditions. The Holocene strata were composed mostly of clayey silt that had formed under transgressive conditions and significant influence of the Lena River runoff and Arctic tundra vegetation on the coast.
1. Introduction
TE D
Key words: Laptev Sea; sediments; permafrost drilling; diatoms; spores; Pleistocene-Holocene
EP
The study of the vast shallow shelf of the Laptev and other East-Arctic Seas of Russia has increased recently due their tremendous hydrocarbon potential and associated economic value, greenhouse gas emission and global warming, Northern Sea Route, and coastal erosion among
AC C
others (Grigoryev et al., 2006; Shakhova et al., 2010; Charkin et al., 2011; Vinogradov et al., 2013; Semiletov et al., 2013; Shakhova et al., 2015). In addition, this region is well suited for the detailed study of paleoclimatic changes and paleogeographical reconstruction due to the optimum preservation of organic remains in the permafrost and alternation of subaqueous and subaerial conditions caused by glacio-eustatic sea-level variations (Romanovskii et al., 2005). The latter are considered responsible for the origin of the rock ice complex and underlying sandy deposits (Bolshiyanov et al., 2007, 2008). The subsea permafrost, widespread in the near-shore shelf zone of the Laptev Sea and other Arctic seas is now under study (Grigoryev and Razumov, 2005; Grigoryev, 2008; Shakhova et al., 2017). The researchers of the Department of Geocryology of the Lomonosov Moscow State University (Romanovskiy and Tumskoy, 2011) indicated the possible
ACCEPTED MANUSCRIPT
existence of a 600–900 m thick permafrost with a complicated multilayer structure. The subsea permafrost of the eastern part of the Russian arctic shelf has been poorly studied due to technical difficulties and risks. The drilling of sea ice in the Sannikov and Dmitriy Laptev Straits allowed geologists of the “Sevmorgeo” and ”VNIIOkeangeologia“ to obtain the information on the shelf’s cryolite zone. Investigations showed that both permafrost and salinised frozen sediments existed in the shelf near-shore zone, though the bottom of the permafrost and cryolite zone have not been
RI PT
stripped as a whole. The most important data on the formation of the sands and ice complex have been obtained from drilling holes on the Laptev Sea shelf in the area of Mamontov Klyk Cape to the west of the Lena River delta (Fig. 1). The marine deposits at a depth of 58 m in Hole C-2 were characterised by diatom marine assemblage, remains of marine mollusk shells and contained marine
SC
pore water with salinities reaching 30 ‰. Evidence of sea deposits such as crushed bivalves, shell
detritus, and barrows were found near Hole C-1 bottom drilled on the shore, highlighting the basin
M AN U
conditions at the time of sedimentation (Bolshiyanov et al., 2007; Rachold et al., 2007; Winterfeld et al., 2011).
In 2011, the first Russian-American expedition conducted scientific drilling of the bottom sediments and permafrost in the near-shore zone in the south-eastern part of Laptev Sea (western part of the Buor-Khaya Bay to the east of Lena River delta). Drilling was conducted from the sea ice under the guidance of I. Semiletov (POI FEB RAS). The main task of the expedition was to drill
TE D
deep holes (up to 100 m) on the shelf to determine the methane potential, that is, the methane amount that may enter the atmosphere from the bottom deposits in the event of further warming and ice destruction in the Arctic. Simultaneously, the composition and structure of the deposits were studied (Sergienko et al., 2012). Subsequently the drilling program was prolonged, investigation
EP
was mostly directed to understand the thermal regime of sea water and subsea permafrost in the East Siberian Arctic Shelf coastal area, a simulation of the warming effect of sea water on subsea
AC C
permafrost integrity, origin of methane and current rates and mechanisms of subsea permafrost degradation of the area (Shakhova et al., 2013; Sapart et al., 2017; Shakhova et al., 2017). Our work aims to acquire new data on the micropaleontological composition of Laptev Sea shelf sediments obtained on these expeditions, to assess their age, genesis, and conditions of sedimentation.
2. Geological characteristics of the study area The Laptev Sea is a shallow epicontinental sea bordered by the Taymyr Peninsula to the west and New Siberian Islands to the east. The sedimentary cover is formed by the Cretaceous-Cenozoic complex underlain by the folded Late Kimmerian (Pre-Aptian) basement (Piskarev et al., 2003; Andieva, 2008; Malyshev et al., 2010). This complex is subdivided into four strata. The Upper Cretaceous stratum (400–3500 m thick) is composed exceptionally of continental coal-bearing
ACCEPTED MANUSCRIPT
molasse. The Paleogene - Lower Miocene stratum (600–5500 m thick) is formed by the alternation of sandstones, siltstones, mudstones, and rarely with interbeds of limestone and diatomites. It is terrigenous, with the development marine facies in the central part of the basin. The MiddleMiocene Pliocene (200–1300 m thick) and Quaternary (175–500 m thick) strata, separated by stratigraphic unconformity, are analogous to the Paleogene - Lower Miocene stratum in the
estimated at 8 to 12 km (Malyshev et al., 2010).
RI PT
lithological composition. The total thickness of the sedimentary cover of the Laptev Sea is
Permafrost with thickness between 400–600 m is widespread on the adjacent land (Derevyagin et al., 2013). The visible thickness of the Late Pleistocene sediments, composed predominantly of ice complex rocks, reaches 40 m (Kaplina, 2009). The ice complex overlaps the complicated relief
SC
and existed before its accumulation; this is evidenced by the same age of the ice complex strata, established by radiocarbon dating of different hypsometric levels of the ice complex. Its uppermost
M AN U
layers were accumulated under conditions of distinctly continental arid climate with tundra-steppe vegetation and very cold winters. The thickness of the Holocene deposits, dominated by sandy loams with lenses and interbeds of peat, usually does not exceed 4–5 m. 3. Material and methods
Holes 1D-11 and 4D-12 were drilled in the western part of the Buor-Khaya Bay (Fig. 1; Table
AC C
EP
TE D
1) to the east of the Lena River delta in the Laptev Sea in 2011 and 2012, respectively.
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 1. Location of the studied Holes (empty circles) and the Holes from Bolshiyanov et al.,
AC C
2007; Rachold et al., 2007; Winterfeld et al., 2011 (red circles). The red line denotes the location of high-resolution seismo-acoustic profile (illustrated in Fig. 2).
Table 1. Information on Holes examined in this study Hole
Longitude E
Latitude N
1D-11 4D-12
130°22,02' 129°52,524'
71°41,58' 71°37,758'
Water depth, m 11 10
Core length, m 52.3 55.8
Year of drilling 2011 2012
High-resolution seismo-acoustic investigations were conducted using a towed high-frequency “GeoPulse Subbottom Profiler” profilograph produced by GeoAcoustics Company. The
ACCEPTED MANUSCRIPT
investigations were conducted in 2008 on board the hydrographic ship “Yakov Smirnitskiy” as a part of “The International Siberian Shelf Study 2008 (ISSS-08)” Project and on the 57th voyage of the RV “Academic M.A. Lavrentyev” in 2011. Signals with 3.5 kHz frequency were used and data were registered in the 3 to 5 kHz frequency interval. The ship’s speed was 5–6 knots. The interval between emissions was 50 mc, which corresponded to a pitch of 13–15 cm. For micropaleontological analysis, 45 samples from Hole 1D-11 and 74 samples from Hole 4D-
RI PT
12 were acquired from all lithological types of sediments. width cm. For spore-pollen analysis 30 g samples were prepared using standard methods (Rudaya, 2010) including boiling samples in 10% KOH solution followed by washing with distilled water. Pollen and spore enrichment was performed using potassium-cadmium (KJ + CdJ2) heavy liquid with a density of 2.3 g/cm3. Diatom
SC
analysis included several steps. To determine diatom content per 1 g of air-dried sediment, 5 g samples were boiled, the sediment was diluted to 100 ml and mixed thoroughly; 0.2 ml of the
M AN U
suspension was used to prepare the slides for counting. To determine the qualitative composition of diatoms, the remainder of the sediment was again boiled with the addition of sodium tripolyphosphate and then washed. Due to the low diatom content all samples were treated with potassium-cadmium (KJ + CdJ2) heavy liquid with a density of 2.6 g/cm3 (Jousé et al., 1974). The slides were prepared using NORLAND synthetic resin with a refractive index of 1.56. The microfossils were studied and photographed using Mikmed-6 and IMAGER.Al light microscopes.
TE D
Spore-pollen nomenclature bases on Pokrovskaya (1966), diatom nomenclature revision follows AlgaeBase (Guiry M., Guiry G., 2018). 4. Results 4.1 Hole 1D-11
EP
High-resolution seismic profiles highlight that the sedimentary cover had a two-layer structure (Fig. 2). The upper layer was formed by acoustically transparent layers that were 2–6 m thick, and
AC C
contained rare, disordered, and short reflections about 10 m long. Generally, the thickness of the upper layer increased north eastwards to the deepest part of the sea. The top of the lower layer was represented by numerous highly intensive reflections, which were 10–150 m in length, and subparallel to the sea bottom. The depth of these reflections was not constant and varied from 2 to 6 m, which resulted in a peculiar saw-like profile of this layer’s upper part. Generally, the acoustic appearance of the lower layer was constant and characterised by the availability of chaotic reflections of different intensities, wherein stratification was absent.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 2. Fragment of the high-resolution seismo-acoustic profile illustrating structure of the upper part of the sediments in the area of Hole 1D-11, Buor-Khaya Bay, Laptev Sea.
A correlation of the seismoacoustic profile with the geological section of Hole 1D-11 (Fig. 3)
TE D
showed that the upper acoustically transparent layer corresponded to the Holocene clayey silt. At the drilling point, the thickness of the clayey silt was 5.5 m, which approximately coincided with our estimation of the thickness of the upper transparent layer (6 m). The lower stratum,
EP
characterised by chaotic reflections, corresponded to the sand layer of the Pleistocene age, containing dense dehydrated silt (DDS) that were about 1.5 m thick. At the point of drilling, the first layer of DDS occurred at a depth of 5.7 m, i.e. in the uppermost part of the sandy formation.
AC C
Thus, the highly intensive reflections, marking the position of the lower layer top, could have been formed at the boundary between the clayey silt of the upper layer and sand of the lower layer or due to the availability of DDS in the sand layer. Thus, the boundary between these layers on the seismoacoustic profile can have a complicated nature. However, based on the complicated saw-like picture of the lower layer top, it may be suggested that this feature is, most likely, a result of migration of the cryogene formations. Therefore, on the seismoacoustic profile, the boundary between the strata most likely corresponds to the top relief of DDS in the Holocene - Pleistocene sediments.
AC C
EP
TE D
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 3. Lithology of Hole 1D-11. 1 - fine sand – coarse sand, 2 - fine sand, 3 - silty sand, 4 – clayey sand, 5 - sandy silt, 6 – dense dehydrated silt (DDS), 7 - clayey silt, 8 – clay, 9 – silty clay; Inclusions: 10 - gravel and pebble, 11 - plant detritus (fragments); Texture: 12 - layered, 13 lenticular; Other symbols:14 - lost horizon of the core, 15 - position of acoustic boundaries on the high resolution seismo-section, 16 - samples taken for micropaleontological analysis, 17 – subsea permafrost. 4.1.1 Diatom analysis Diatoms were predominantly found in the upper part of the core in the 75–77 cm, 250-252 cm, 330-332 cm, and 415-417 cm intervals composed of clayey silt. Diatom concentration varies from 1700 to 14730 valves per gram of air-dried sediment, while in surface sediments of this region
ACCEPTED MANUSCRIPT
diatoms were relatively abundant (250-800 thousand valves/g) (Obrezkova et al., 2014; Tsoy and Obrezkova, 2017). Diatoms are represented by 73 species and intraspecific taxa belonging to 35 genera (Table 2; Plates 1-3). The genera richest in species and intraspecific taxa are Pinnularia (6 taxa), Gomphonema (6), Navicula (5), Cymbella (5), Aulacoseira (5), Thalassiosira (3), Stauroneis (3), Placoneis (3), Eunotia (3), Tabellaria (2), Epithemia (2), Encyonema (2), Diploneis (2), Diatoma (2), Amphora (2), and Alveolophora (2). Other genera are represented by single species.
RI PT
Most species are freshwater (60 taxa), 12 species are marine and brackish water, and 1 species is
AC C
EP
TE D
M AN U
SC
known from both fresh and marine waters.
Plate 1. Freshwater (1-10, 12, 13) and marine diatoms recovered from Hole 1D-11, BuorKhaya Bay, Laptev Sea. 1 – Cymbella cymbiformis C. Agardh; 2 – Cymbella cymbiformis var. nonpunctata Fontel; 3 – Amphora ovalis (Kützing) Kützing; 4 – Epithemia adnata (Kützing) Brebisson; 5 – Epithemia sorex Kützing; 6 – Eunotia bidens Ehrenberg; 7 – Eunotia praerupta Ehrenberg; 8 – Eunotia siberica Cleve; 9 – Cymbopleura inaequalis (Ehrenberg) Krammer; 10 –
ACCEPTED MANUSCRIPT
Placoneis amphibola (Cleve) E.J.Cox; 11 – Navicula valida Cleve & Grunow; 12 – Diploneis ovalis (Hilse) Cleve; 13 – Cocconeis placentula var. lineata (Ehrenberg) Van Heurck.
AC C
EP
TE D
M AN U
SC
RI PT
1, 2, 4-7, 9-13 (330-332 cm); 3 (250-252 cm); 8 – (75-77 cm). Scale bar 10 µ
Plate 2. Freshwater diatoms recovered from Hole 1D-11, Buor-Khaya Bay, Laptev Sea. 1,2 – Pinnularia viridis (Nitzsch) Ehrenberg; 3 – Pinnularia crucifera Cleve-Euler; 4 – Hantzschia amphioxys (Ehrenberg) Grunow; 5 – Craticula cuspidata (Kutzing) D.G.Mann; 6 – Stauroneis phoenicenteron (Nitzsch) Ehrenberg; 7, 8 – Caloneis silicula (Ehrenberg) Cleve; 9, 10 – Gomphonema olivaceum (Hornemann) Brébisson; 10 – Gomphonema brebissonii Kützing; 11 – Gomphonema truncatum Ehrenberg. 2, 8, 9 (250-252 cm); 1, 3-7, 11, 12 (330-332 cm); 10 (415-417 cm). Scale bar 10 µ Diatom assemblages from the 75–77 cm, 250-252 cm, 330-332 cm, and 415-417 cm intervals are dominated by fresh-water species Aulacosei ra subarctica (Müller) Harworth (14-39% of total
ACCEPTED MANUSCRIPT
number) and marine brackishwater species Thalassiosira baltica (Grunow) Ostenfeld (11-33%) (Plate 1). Other species are mostly represented by single occurrences or are extremely rare (Table 2). In some intervals freshwater species Alveolophora jouseana (Moiseeva) Moiseeva and A.
EP
TE D
M AN U
SC
RI PT
robusta (Khursevich) Usoltseva & Khursevich, which became extinct in the Miocene, were found.
Plate 3. Diatoms recovered from Hole 1D-11, Buor-Khaya Bay, Laptev Sea. 1-3 – Aulacoseira subarctica (Müller) Harworth; 4, 5 – Thalassiosira baltica (Grunow) Ostenfeld; 6 – Rhizosolenia
AC C
hebetata Bailey; 7, 8 – Thalassiosira hyperborea (Grunow) Hasle; 9 – Didymosphenia geminata (Lyngbye) Schmidt; 10 – Lindavia costata (L.P. Loginova, E.G. Lupikina & G.K. Khursevich) T. Nakov et al.; 11 – Aulacoseira praegranulata (Jousé) Simonsen; 12, 13 – Alveolophora jouseana (Moiseeva) Moiseeva; 14-17 – Alveolophora robusta (Khursevich) Usoltseva & Khursevich; 18, 19 – Paralia crenulata (Grunow) Gleser; 20 – Paralia grunowii Gleser. 1-10 – recent. 11-20 – extinct species. 1-3, 9-17 – freshwater, 4-8, 18-20 – marine diatoms. 1, 2, 5, 6, 8, 14-17 (330-332 cm); 3, 10 (75-77 cm); 4, 7, 9, 11 (250-252 cm interval); 12, 13 (415-417 cm); 18-20 (4130-4132 cm. Scale bar 10 µ
ACCEPTED MANUSCRIPT ecology
Table 2. List of diatom taxa and their number in samples of the core of Hole 1D-11. Taxa
Interval, cm 7577
250252
Alveolophora jouseana (Moiseeva) Moiseeva in Moiseeva & Nevretdinova A. robusta (Khursevich) Usoltseva & Khursevich
fw,ex
Amphora libyca Ehrenberg
m
A. ovalis (Kützing) Kützing Aulacoseira ambigua (Grunow) Simonsen
fw fw
2
A. granulata (Ehrenberg) Simonsen
fw
3
A. islandica (Müller) Simonsen
fw
2
A. praegranulata (Jousé) Simonsen
fw,ex
2
3
A. subarctica (Müller) Harworth
fw
18
14
Caloneis silicula (Ehrenberg) Cleve
fw
Cocconeis placentula var. lineata (Ehrenberg) Van Heurck
fw
Coscinodiscus oculus iridis Ehrenberg
m
C. sibiricus Strelnikova? Craticula cuspidata (Kutzing) D.G.Mann
m, ex
Cymbella cf. arctica (Lagerstedt) Schmidt C. cistula (Ehrenberg) O.Kirchner C. cymbiformis C.Agardh C. cymbiformis var. nonpunctata Fontel Cymbella sp.
3
2
27702772
35303532
41304132
1
1 2
2
1
fw fw
1
2
2
15
SC
1
1
1 1 1
fw
1
Diatoma mesodon (Ehrenberg) Kűtzing Diatoma vulgaris Bory
Didymosphenia geminata (Lyngbye) Schmidt
fw
Diploneis ovalis (Hilse) Cleve
fw
1
fw
1
fw
1
TE D
2
1
fw
EP
*
1
fw
1
1 1
1
1 2
1
Encyonema elginense (Krammer) Mann E. silesiacum (Bleish) D. Mann.
fw
2
Epithemia adnata (Kützing) Brebisson
fw
4
E. sorex Kützing
fw
1
1
Eunotia bidens Ehrenberg
fw
1
1
E. praerupta Ehrenberg
fw
4
E. siberica Cleve
fw
1
Fragilaria capucina Desmazières
m/fw
Gladiopsis speciosus (Schulz) Gersonde et Harwood
m, ex
Gomphonema affine Kützing
fw
G. brebissonii Kützing
fw
2
G. olivaceum (Hornemann) Brébisson Gomphonema spp.
fw
1
fw
4
G. truncatum Ehrenberg
fw
1
G. ventricosum W.Gregory
fw
1
AC C
*
2
fw fw
40
1
fw
bw
2
RI PT
2
1 1
fw
1 1
Cymbopleura inaequalis (Ehrenberg) Krammer
Diploneis sp.
415417 1
fw,ex
M AN U
Cyclotella striata (Kützing) Grunow)
330332
1
1
1
1
4
4
1
1
5
5
3
1 *
1
1
2 1 2
ACCEPTED MANUSCRIPT
Hannaea arcus (Ehrenberg) R.M.Patrick Hantzschia amphioxys (Ehrenberg) Grunow
fw
Melosira arctica (Ehrenberg) Dickie Meridion circulare (Greville) Agardh
m m
Navicula digitoradiata (Gregory) Ralfs
m
N. impexa Hustedt
fw
N. radiosa Kützing
fw
Navicula sp.
fw
N. valida Cleve & Grunow
m
Nitzschia sigma (Kützing) W.Smith
bw
Odontidium hyemale (Roth) Kützing
fw
Paralia crenulata (Grunow) Gleser
7577
330332
P. sulcata (Ehrenberg) Cleve Pinnularia crucifera Cleve-Euler
1
fw
P. major (Kützing) Rabenhorst P. stomatophora Grunow P. streptoraphe Cleve
2
1
1
1
1
1
1
1
1
1
2
P. gastrum (Ehrenberg) Mereschkowsky
fw
P. placentula (Ehrenberg) Heinzerling
fw
1
Rhizosolenia hebetata Bailey
m
1
1
1
1
1
1
3
1 1 1
fw
1
3
fw
S. laevissima (Kützing) D.G.Mann
fw
1
Stauroneis anceps Ehrenberg
fw
1
S. phoenicenteron (Nitzsch) Ehrenberg
fw
2
2
Stauroneis siberica (Grunow) Lange-Bertalot & Krammer Tabellaria fenestrata (Lyngbye) Kützing
fw 3
2
Tabellaria flocculosa (Roth) Kűtzing Thalassiosira baltica (Grunow) Ostenfeld
fw m, bw m
AC C
Sellaphora bacillum (Ehrenberg) D.G.Mann
Thalassiosira constricta Gaarder Thalassiosira hyperborea (Grunow) Hasle Ulnaria ulna (Nitzsch) P.Compère
*
1
1
2
*
*
1
fw
EP
1
1
Placoneis amphibola (Cleve) E.J.Cox
Rhopalodia gibba (Ehrenberg) O. Müller
41304132
1
fw
fw
35303532
1
fw
TE D
P. viridis (Nitzsch) Ehrenberg
27702772
4
fw
P. episcopalis Cleve
415417
1
fw
m, ex m, ex m, bw fw
250252
M AN U
P. grunowii Gleser
Interval, cm
SC
Taxa
RI PT
ecology
Table 2. Continued.
1
1 fw
m, bw fw
2
3
1 8
26
23
16
1 4
2
3
1
1
1
1
4
Total number in a slide
25
38
56
36
Number of taxa recognized
30
25
53
30
1
1
Notes: Acronyms for ecological characteristics of diatoms: fw – freshwater, bw – brackishwater, m – marine, ex – extinct diatoms; * - sporadically occurred diatoms.
4
ACCEPTED MANUSCRIPT
The latter species has been recently identified in the Middle-Late Miocene lake deposits of the Vitim Highland (Usoltseva and Khursevich, 2013) surrounded by the Vitim River, the right tributary of the Lena River. Due to the abrasion of the Miocene lake sediments, this species arrived with the tributary waters of the Lena River into the sediments of the Buor-Khaya Bay. Marine brackish-water species Thalassiosira hyperborea (Grunow) Hasle, T. constricta Gaarder, Cyclotella striata (Kützing) Grunow, and Melosira arctica (Ehrenberg) Dickie occurred with a single
RI PT
specimen. The latter is a typical arctic species that vegetates in sea ice. The oceanic cold-water species Rhizosolenia hebetata Bailey was also found in 75-77 and 330-332 intervals.
Diatoms were not found in the 560–3532 cm interval, except in the 2770–2772 cm interval, where the tychopelagic species Paralia sulcata (Ehrenberg) Cleve that is characteristic of low
Coscinodiscus oculus iridis Ehrenberg was found.
SC
salinity sea waters was noted; and the 3530–3532 cm interval, where the planktonic oceanic species
M AN U
In the 4130–4132 cm interval, half-dissolved indefinable valves of diatoms as well as isolated diatoms represented by marine extinct species Paralia grunowii Gleser and P. crenulata (Grunow) Gleser (Plate 3), fragments of species that look like Gladiopsis speciosus (Schulz) Gersonde & Harwood, and Coscinodiscus sibiricus Strelnikova were found. The Paralia grunowii Gleser has been known from the Cretaceous, P. crenulata (Grunow) Gleser species is typical of the Late Cretaceous-Paleogene deposits, and Gladiopsis speciosus (Schulz) Gersonde & Harwood and
TE D
Coscinodiscus sibiricus Strelnikova species are restricted to the Late Cretaceous. These species are common in the Cretaceous deposits of the East Urals (Strelnikova, 1974), the Paleogene of the West Siberia, and Lomonosov Ridge of the Central Arctic (Kim and Glezer, 2007), Campanian deposits of the Upper Cretaceous of the Arctic Archipelago, and the Horton River section of the
EP
northwestern coast of Canada (Tapia and Harwood, 2002). It is suggested that the species found in the 4130–4132 cm interval were redeposited. In the study area of Laptev Sea, Cretaceous deposits
AC C
are essentially continental, implying that the sources of the extinct marine species of diatoms are probably Cretaceous and Paleogene marine deposits widespread in the Arctic region. Below, in the 4220–5232cm interval, diatoms were not found; only isolated spicules of sponges were noted in the 4320–4330 cm interval.
Thus, the diatoms found in the clayey silt of the upper part (interval 0–417 cm) of Hole 1D-11, are common in the modern and Holocene sediments at the mouth of the Lena River in Laptev Sea (Polyakova, 1997; Cremer, 1999; Bauch and Polyakova, 2000; Tsoy, 2001; Matul et al., 2007; Obrezkova and Tsoy, 2008; Obrezkova et al., 2014). They are characterised by the predominance of fresh-water diatoms, supplied by the Lena River run-off, and insignificant amount of marine brackish-water species, as well as the presence of redeposited fresh-water species that became extinct in the Miocene. Below, in the 560–5232 cm interval, diatoms were practically inexistent
ACCEPTED MANUSCRIPT
with the exception of 2770–2772 cm and 3530–3532 cm intervals where isolated marine species have been noted. The fossilised marine species of diatoms, found in the 4130–4132 cm interval, are typical of Cretaceous-Paleogene deposits of the Arctic region and are, most likely, redeposited. Vegetal detritus and coaly particles were found in all the examined samples and are typical of Laptev Sea sediments (Holmes and Creager, 1974). 4.1.2 Spore-pollen analysis
RI PT
In the upper part of the sedimentary cover (interval 0–417 cm, clayey silt) a group of wood species comprising 48–70 % was identified. They were characterised by the predominance of Pinus pollen (chiefly Pinus pumila - 32-51 %; Pinus silvestris - 8-22 %), followed by pollen of the Betulaceae family (22-44 %), which were essentially of the shrubs Betula and Alnaster.
SC
Concentration of pollen of dark conifers species varies from 3–15 % (Table 3, Fig. 4).
Table 3. Percentage of the pollen and spores in Hole 1D-11 Pollen of
wood
grasses and
species
shrubs
0–417
48–70
2-15
24-56
670–772
50-56
11-17
32-33
880–882
70
10
20
2240–2242
72
4
23
cm
Spores
Pollen of dark
Pollen
Pollen Pinus
Pollen of
conifers
Pinus
silvestris
Betulaceae
species
pumila
3-15
32-51
8-22
22-44
3-4
20-22
6-7
68-69
10
37
13
40
49
24
21
4
M AN U
Pollen of
TE D
Intervals,
family
Grasses and shrubs constituted 2-15 %; pollen grains of Ericales, Asteraceae, Caryophyllaceae, and others were present. Cryptogamic plants (24-56 %) were mostly represented by the spores of
EP
the Polypodiaceae, Sphagnum family; spores of Bryales, Lycopodium were found in lesser amount. The spore-pollen spectrum reflects the composition of the current flora found in north of East
AC C
Siberia. Naidina (2009) and Savelyeva et al. (2011) noted the understated representation of cryptogamic plants, which are common in the tundra zone and often dominate the plant cover. It is suggested that sediments containing the above spore-pollen complex, were formed in the Holocene. Redeposited pollen grain samples of Lycopodium, Ophyoglossaceae, Osmunda, Schizeaceae?, Podocarpus?, Tsuga, Picea, Abies, Pinus, Juglans, Pterocarya, Ulmus, Syringa?, and Tilia were also found.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
Fig. 4. Spore-pollen diagram of Hole 1D-11 upper part, Buor-Khaya Bay, Laptev Sea. AP -
TE D
pollen of trees; NAP - pollen of shrubs and grasses; SP - spores.
In the 670–780 cm interval (670–672 cm - silt, 770–772 cm - fine sand), a group of wood
EP
species pollen (50–56 %) including the Betulaceae family (68-69 %) bush birches, and alders (Duschekia fruticosa Alnaster) were dominant. Among the Pinus pollen, P. pumila constituted 2022 % and P. silvestris constituted 6-7 %. Dark conifers pollen accounted for 3-4 %. In the group of
AC C
grasses and shrubs, pollen grains of Ericales, Asteraceae, Umbelliferae, Campanulaceae, and others were found. The spectrum composition was similar to the palinospectra characteristic of Early Holocene of the Arctic eastern sector, reflecting the vegetation of the Arctic tundra (Naidina, 2011). The increased content of the Betula pollen in the spectrum may indicate relatively warm climatic conditions (Naidina, 2009). Most part of the Arctic shelf shows depths of less than 100 m and has formed over the past last 11.7 thousand years (Naidina, 2011). Possible presence of the Lena River delta located somewhat to the north during the Pre-Holocene era, can explain the low or nonexistent quantities of pollen at below 770–772 cm level as conditions favouring its accumulation were poor. In the 880–882 cm interval (silt), microfossils in the spectrum were few in number, but the pollen of wood species dominated (70 %), represented chiefly by Pinus (Pinus pumila - 37 %;
ACCEPTED MANUSCRIPT
Pinus silvestris - 13 %); pollen of small-leaf species of the Betulaceae family was lower (40 %). The pollen of dark-needle conifers constituted 10 %, mainly comprising of Picea and more rarely Abies pollen. The pollen of grasses and shrubs was little, amounting to 10 % (including Asteraceae, Cyperaceae, Onagraceae, Ericales, and others). Cryptogamic plants (20 %) were mainly represented by Polypodiaceae, Sphagnum, and to a lesser extent by Lycopodium and Bryales. Redeposited pollen grains of Picea, Pinus, Juglans, and Quercus were also found.
RI PT
In the 2240–2242 cm interval (silty sand), the pollen level was very little and amounted to around 111 pollen grains per specimen. However, a conventional spore-pollen spectrum was distinguished, which was dominated by the pollen of trees (72 %) (Table 2, Fig. 4). Dark-needle species, particularly Picea, accounting for 49 %, were predominant. Pinus pollen amounted to 32 %
SC
of the Pinus sect. Cembrae pollen (including P. sibirica and P. Pumila) constituted 24 %, and the Pinus sect. Eupitys (Pinus silvestris) pollen accounted for nearly 21 %. Pollen of small-leaved
M AN U
species of the Betulaceae family and grasses were isolated. Cryptogamic plants (23 %) were represented by Osmunda, Lycopodium, Sphagnum, Polypodiaceae, and others. Isolated redeposited spores of Lygodium? and isolated pollen grains of Abies were noted.
The depleted palinospectrum established for this interval was dominated by the pollen of darkneedle species and is typical of Pleistocene deposits. The presence of redeposited spores and pollen of the Tertiary age is common in the Quaternary sediments (Derevyanko and Gusev, 2011) and
TE D
testifies to the erosion and degradation of the Paleogene and Neogene strata widespread on the Arctic shelf of Russia and adjacent land.
In the sediments of the lower part of Hole 1D-11 (interval 2770–5100 cm), represented mainly by silty sand, pollen and spores were absent or in insignificant quantities. The microfossils were
EP
strongly mineralised, but their composition (Pinus, Picea, and Betulaceae family) conditionally allows us to suggest Pleistocene age of the sediments.
AC C
The micropaleontological study of the sediments of the eastern part of the Lena River delta, stripped by Hole 1D-11, suggests that the sediments in the upper 772 cm were probably formed in the Holocene under transgressive conditions with significant influence of the Lena River flow and Arctic tundra vegetation on the shore; those in the lower 772–5230 cm were formed in the Pleistocene, predominantly under continental conditions.
M AN U
SC
RI PT
ACCEPTED MANUSCRIPT
TE D
Plate 4. Spores and pollen from core of Hole 1D-11, Buor-Khaya Bay, Laptev Sea. Spores: 1 – Polypodiaceae; 2, 3 – Lycopodium sp.; 4 – Bryales; 5-6 – Sphagnum sp. Pollen: 7 – Picea sect. Eupicea; 8 – Picea sect. Omorica; 9-11 – Pinus silvestris L.; 12, 13 – Pinus sect. Cembrae; 14, 15 – Betula sect. Albae; 16 – B. exilis Sukacz.; 17, 18 – B. middendorffii Trautv. et Mey; 19-22 – Alnus
EP
sp.; 23-26 – Alnaster (Dushekia) sp.; 27, 28 – Salix sp.; 29 – Compositae; 30 – Artemisia sp.; 31 –
AC C
Ericales; 32 – Cariophyllaceae. 1-32 (75-77 cm interval). Scale bar 20 µ
4.2 Hole 4D-12
Hole 4D-12 was drilled to the northwest of Muostakh Island to a depth of about 10 m and 55.8 m thick sediments were collected. They were mostly composed of the clayey silt of different densities and sand (Fig. 5). Diatoms were not found over the entire column length, redeposited pollen and spores occurred sporadically. Redepositions were found at 115–117 cm level and included Lycopodium, Picea sp., Pinus sect., Cembrae, Pinus sect. Eupitys, and Ericales, which were not likely to be older than the Pleistocene. Isolated pollen grains of Podocarpus, Dacridium, and Tsuga and ancient spores belonging to the Schizaceae Family, supposedly of the Paleogene age, were found down the column. Due to very low content to total absence of microfossils in the Hole
ACCEPTED MANUSCRIPT
4D-12, the column can be rather conditionally divided into two intervals: Holocene from 0–120 cm
AC C
EP
TE D
M AN U
SC
RI PT
and Pleistocene from 120–4420 cm. Further identification of detailed subdivisions was not possible.
Fig. 5. Lithology of Hole 4D-13. Lithologic and other symbols are explained on Figure 3.
5. Discussion
ACCEPTED MANUSCRIPT
We observed that microfossils were rare in the in the lower part (560–5232 cm interval) of the shelf zone sediments of the Buor-Khaya Bay (Laptev Sea) represented mostly by silty sand, stripped by Hole 1D-11 (in 2011). Diatoms were practically not found, with the exception of 2770– 2772 cm and 3530–3532 cm intervals where isolated marine species have been noted. The fossilised marine species of the diatoms, found in the 4130–4132 cm interval, are typical to the CretaceousPaleogene deposits of the Arctic region and are, most likely, transported and redeposited from there.
RI PT
Spores and pollen in this part of the Hole were isolated or absent, with the exception of 880– 882 cm and 2240–2242 cm intervals where the depleted palinospectra were dominated by the pollen of wood species such as dark-needle conifers and birch, and isolated redeposited spores and pollen were observed. The composition (Pinus, Picea, fam. Betulaceae) suggests somewhat conditionally
SC
Pleistocene age of the sediments.
The sediments of the upper part (0–417 cm) of the Hole contained diatoms that are common in
M AN U
the modern sediments of the Lena River delta of the Laptev Sea; they were probably formed under close conditions. They were characterised by the predominance of fresh-water diatoms supplied by the Lena River run-off, an insignificant amount of coastal-marine species, and the presence of the redeposited fresh-water species that became extinct in the Miocene.
The spore-pollen spectrum from the sediments of this interval reflects the composition of vegetation that can be currently found in the north of East Siberia and is typical to Holocene
TE D
sediments of this region (Rudenko et al., 2014). The formation of marine spore-pollen spectra is simultaneously influenced by several factors such as wind scattering, river flows, and abrasion of banks (Naidina, 2009). The Lena River run-off played an important role by transporting significant amount of sediments into the sea in the form of very fine particles (including plant pollen), which
EP
accumulated on the shelf. The modern flora of the Laptev Sea coast is characterised by forest-free landscapes. The pollen of trees, shrubs, and grasses is abundant in the marine deposits of the upper
AC C
part of Hole 1D-11 and appear to reflect the vegetation of nearby shores as well as the regional vegetation of Yakutia (Naidina, 2011). Big rivers can supply pollen and spores to distances up to 4000 km (Sladkov, 1967). The detection of palinospectra of the pollen of Picea, Abies, and Pinus silvestris, whose area is far to the south, may be explained by cyclones and winds blowing predominantly from southwest to northeast (Naidina et al., 2000; Naidina, 2009). However, it is possible that the initial stage of the Holocene began earlier, in the 770–772 cm interval, as the spore-pollen spectrum characterizes the beginning of the Holocene of the Arctic eastern sector, reflecting the vegetation of the Arctic tundra. However, the low content of diatoms, spores, and pollen in the Holocene-Pleistocene sediments of the eastern part of the Lena River delta, stripped by the Holes, rendered it impossible to distinguish detailed subdivisions.
ACCEPTED MANUSCRIPT
6. Conclusions
The micropaleontological (diatoms, palinoflora) study of the deposits, stripped by Holes 1D-11 and 4D-12, has established that the sedimentary section is subdivided into two different-age strata Late Pleistocene and Holocene that were formed under different conditions. The Pleistocene stratum, composed of different-grain sands containing cryogene inclusions about 1.5 m thick, was formed under continental conditions. The Holocene stratum, composed predominantly of clayey
RI PT
silt, was developed under transgressive conditions with significant influence of the Lena River runoff with vegetation of the Arctic tundra on the coast.
Acknowledgments
SC
The authors thank L.V. Osipova for the chemical-technical treatment of the samples for the micropaleontological analysis, I.V. Chervinskaya and N.S. Lee for the graphic works. We are
helped improve the manuscript. Funding:
This
research
was
M AN U
grateful to Dr. U.P. Vasilenko and one anonymous reviewer for their constructive comments that
supported
by
the
Russian
Government
(no.
14.Z50.31.0012/03.19.2014) and Russian Science Foundation (no. 16-17-10109).
TE D
References
Andieva, T.A., 2008. Tectonic position and major structures of the Laptev Sea / Petroleum Geology - Theoretical and Applied Studies. 3(1): 1-27. www.ngtp.ru. Bauch, H.A., Polyakova, Y.I., 2000. Late Holocene variations in Arctic shelf hydrology and sea-ice
569-577.
EP
regime: evidence from north of the Lena Delta. International Journal of Earth Sciences. 89:
AC C
Bolshiyanov, D.Y., Grigoryev, M.N., Shnaider, V., Rakhold, F., Overduin, P., Hubberten, H., Makarov, A.S., Gusev, E.A. 2007. Fluctuations of the sea level and formation of the rock ice complex on the coast of the Laptev Sea in the Late Neo-Pleistocene. Materials of the V AllRussia Meeting on the study of the Quaternary period. Moscow. GEOS: 45-49. Bolshiyanov, D.Y., Makarov, A.S., Gusev, E.A., Shanider, V. 2008. Problems of Ice Complex origination and former «Sannikovs Lands» existence in the Laptev Sea. Problems of the Arctic and Antarctic continents. 1(78): 151-160. Charkin, A. N., Dudarev, O. V., Semiletov, I. P., Kruhmalev, A. V., Vonk, J. E., Sánchez-García, L., Karlsson, E., Gustafsson, Ö. 2011. Seasonal and interannual variability of sedimentation and organic matter distribution in the Buor-Khaya Gulf: the primary recipient of input from Lena
ACCEPTED MANUSCRIPT
River and coastal erosion in the southeast Laptev Sea, Biogeosciences, 8, 2581–2594, doi:10.5194/bg-8-2581-2011. Cremer, H. 1999. Distribution patterns of diatom surface sediment assemblages in the Laptev Sea (Arctic Ocean). Marine Micropaleontology. 38: 39-67. Derevyagin, A.Y., Chizhov, A.V., Maier, X., Opel, T., Schirrmeister, L., Wetterich, S. 2013. Isotopic composition of texture ices, Laptev sea coast. Earth`s Cryosphere. 17(3): 27-34.
RI PT
Derevyanko, L.G., Gusev, E.A. 2011. Redeposited spores and pollen in the Holocene sediments of the outer part of the Arctic shelf of Russia // Problems of the modern palinology: Materials of the XIII Russian Palinological Conference with the international participation (Syktyvkar, Komi Republic, September 5-8, 2011). Syktyvkar: IG of the Komi Scientific Center of the
SC
Urals Branch of RAS. II: 74-77.
Grigoryev, M.N. 2008. Cryomorphogenesis and lithodynamics of the coastal-shelf zone of the seas
M AN U
of the Eastern Siberia. Thesis of the Doctor of geographical sci. Yakutsk. pp.291. Grigoryev, M.N., Razumov, S.O. 2005. Distribution and evolution of the subaqual frozen ground in the coastal-shelf zone of the Laptev and East-Siberian Seas as a result of the many-year transformation of the coastal zone. Present geodynamics and dangerous natural processes in Central Asia. Irkutsk: Publishing House of the Institute of the Earth’s Crust, the Siberian Branch of RAS. 2: 136-155.
TE D
Grigoryev, M.N., Razumov, S.O., Kunitskiy, V.V., Spektor, V.B. 2006. Dynamics of the Russian East Arctic Sea coast: major factors, regularities and tendencies. Earth`s Cryosphere. X(4):7494. http://www.izdatgeo.ru.
Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National
EP
University of Ireland, Galway. http://www.algaebase.org. Holmes, M.L., Creager, Y.S. 1974. Holocene history of the Laptev Sea Continental Shelf. Marine
AC C
Geology and Oceanography of the Arctic Seas. 211-229. DOI 10.1007/978-3-642-87411-6_9. Jousé A.P., Proschkina-Lavrenko A.I., Ssheshukova-Poretskaya V.S. 1974. Method of research. In: Diatoms of the USSR Fossil and Recent. Vol. I, pp. 50–79. Nauka, Leningrad. Kaplina, T.N. 2009. Alas complex of north Yakutia. Earth`s Cryosphere. XIII(4): 3-17. Kim, B.I., Glezer, Z.I. 2007. Sedimentary cover of the Lomonosov Ridge: Stratigraphy, structure, deposition history, and ages of seismic facies units. Stratigraphy and Geological correlation. 15(4): 401-420. Malyshev, N.A., Obmetko, V.V., Borodulin, A.A. 2010. Evaluation of the oil-gas content of sedimentary basins of the East Arctic. Scientific-technical Bulletin of the OAO NK “Rosnefte”. 1:20-28.
ACCEPTED MANUSCRIPT
Matul, A.G., Khusid, T.A., Mukhina, V.V., Chekhovskaya, M.P., Safarova, S.A. 2007. Recent and Late Holocene environments on the southeastern shelf of the Laptev Sea as inferred from microfossil data. Oceanology. 47(1): 80-90. Naidina, O.D. 2009. Environmental changes in the eastern shelf of the Laptev Sea in the late-glacial time. Stratigraphy and Geological correlation. 17(5): 95-108. Naidina, O.D. 2011. Pollen “tells” … about the climate of the past. Science in Russia. 3: 54-60.
RI PT
Naidina, O.D., Baukh, H.A., Kassence, H. 2000. First data on the distribution of pollen and spores in the surface sediments of the Laptev Sea and their importance for the paleoclimatic reconstructions of the Holocene of the Arctic Siberia. Bulletin of Moscow Society of Naturalists. Geological Branch. 75(1): 67-72.
SC
Obrezkova, M.S., Kolesnik, A.N., Semiletov, I.P. 2014. The diatom distribution in the surface sediments of the Eastern Arctic Seas of Russia. Russian Journal of Marine Biology. 40(6): 465-
M AN U
472. DOI: 10.1134/S1063074014060170
Obrezkova, M.S., Tsoy, I.B. 2008. Diatom flora of the Holocene sediments of the Russian EastArctic seas. Bulletin of FEB RAS. 1:136-143.
Pokrovskaya, I.M. 1966 (Ed.). Paleopalynology, Nedra, Leningrad. Vol. 3. 368 pp. (in Russian). Piskarev, A.L., Soroka, I.V, Chernyshev, M.Y. 2003. Structure of the earth crust and tectogenesis in the Laptev Sea. Geotectonics. 3:57-72. (In Russian)
pp. 146.
TE D
Polyakova, E.I. 1997. Arctic seas of Eurasia in the Late Cenozoic time. Moscow: Scientific World.
Rachold, V., Bolshiyanov, D.Y., Grigoriev, M.N., Hubberten, H.W., Junker, R., Kunitsky, V.V., Merker, F., Overduin, P.P., Schneider, W. 2007. Near-shore Arctic subsea permafrost in
EP
transition. EOS: Transactions of the American Geophysical Union. 88(13): 149-156. Romanovskii, N., Hubberten, H., Gavrilov, A., Eliseeva, A., Tipenko, G. 2005. Offshore permafrost
AC C
and gas hydrate stability zone on the shelf of East Siberian Seas. Geo-Mar. Lett. 25: 167-182. doi:10.1007/s00367-004-0198-6 Romanovskiy, N.N., Tumskoy, V.E. 2011. Retrospective approach to the estimation of the contemporary extension and structure of the shelf cryolithozone in East Arctic. Earth`s Cryosphere. XV(1): 3-14. http://www.izdatgeo.ru. Rudaya, N.A. 2010. Palinological analysis: teaching-methodical manual. Novosibirsk State University, Institute of Archaeology and Ethnography, Siberian Branch of RAS. 48 p. Rudenko O., Tarasov P.E., Bauch H.A., Taldenkova E. 2014. Quaternary International 348; 82-92. http://dx.doi.org/10.1016/j.quaint.2014.04.032 Sapart C.J., Shakhova N., Semiletov I., Jansen J., Szidat S., Kosmach D., Dudarev O., van der Veen C., Egger M., Sergienko V., Salyuk A., Tumskoy V., Tison J.L., Rockmann T. 2017. The origin
ACCEPTED MANUSCRIPT
of methane in the East Siberian Arctic Shelf unravelled with triple isotope analysis. Biogeosciences. 14(9):2283-2292. doi: 10.5194/bg-14-2283-2017 Savelyeva, L.A., Morozova, E.A., Titova, D.V. 2011. Subfossil spore-pollen spectra and modern vegetation of the Lena River delta. Problems of the modern palinology: Materials of the XIII Russian Palinological Conference with the international participation (Syktyvkar, Komi Republic, September 5-8, 2011). Syktyvkar: IG of the Komi Scientific Center, Urals Branch of
RI PT
RAS. 1: 102-103.
Semiletov, I.P., Shakhova, N.E., Pipko, I.I., Pugach, S.P., Charkin, A.N., Dudarev, O.V., Kosmach, D.A., Nishino, S. 2013. Space-time dynamics of carbon and environmental parameters related to carbon dioxide emissions in the Buor-Khaya Bay of the Laptev Sea. Biogeosciences. 10:
SC
5977-5996, www.biogeosciences.net/10/5997/2013/doi:10.5194/bg-10-105977-2013.
Sergienko, V. I., Lobkovskii, L. I., Semiletov, I. P., Dudarev, O. V., Dmitrievskii, N. N., Shakhova,
M AN U
N. E., Romanovskii, N. N., Kosmach, D. A., Nikol’skii, D. N., Nikiforov, S. L., Salomatin, A. S., Anan’ev, R. A., Roslyakov, A. G., Salyuk, A. N., Karnaukh, V.V., Chernykh, D. B., Tumskoi, V. E., Yusupov, V. I., Kurilenko, A. V., Chuvilin, E. M., and Bukhanov, B. A. 2012. The Degradation of Submarine permafrost and the destruction of hydrates on the shelf of East Arctic Seas as a potential cause of the “Methane Catastrophe”: some results of integrated studies in 2011. Dokl. Earth Sci. 446: 1132–1137.
TE D
Shakhova N., Semiletov I., Gustafsson O., Sergienko V., Lobkovsky L., Dudarev O., Tumskoy T., Grigoriev M., Mazurov A., Salyuk A., Ananiev R., Koshurnikov A., Kosmach D., Charkin A., Dmitrevsky N., Karnaukh V., Gunar A., Meluzov A., Chernykh D. 2017. Current rates and mechanisms of subsea permafrost degradation in the East Siberian Arctic Shelf. Nature
EP
communications. doi: 10.1038/ncomms15872
Shakhova, N., Semiletov I., Leifer I., Sergienko V., Salyuk A., Kosmach D., Chernykh D., Stubbs
AC C
C., Nicolsky D., Tumskoy V., Gustafsson Ö. 2013. Ebullition and storm induced methane release from the East Siberian Arctic Shelf. Nature Geoscience, 7, doi: 0.1038/ NGEO2007 Shakhova, N., Semiletov, I., Salyuk, A., Yusupov, V., Kosmach, D., Gustafsson, O. 2010. Extensive methane venting to the atmosphere from sediments of the East Siberian Arctic Shelf. Science. 327:1246-1250. doi:10.1126/science.1182221 Shakhova, N., Semiletov, I., Sergienko, V., Lobkovsky, L., Yusupov, V., Salyuk, A., Salomatin, A., Chernykh, D., Kosmach, D., Panteleev, G., Nicolsky, D., Samarkin, V., Joye, S., Charkin, A., Dudarev, O., Meluzov, A., Gustafsson, O. 2015. The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice. Philosophical. Transactions of the Royal Society. 373: 20140451. http://dx.doi.org/10.1098/rsta.2014.0451 Sladkov, A.N. 1967. Introduction to the spore-pollen analysis. Moscow: Nauka. pp 270.
ACCEPTED MANUSCRIPT
Strelnikova, N.I. 1974. Diatoms of the Late Cretaceous (West Siberia). Moscow: Nauka. pp 204. Tapia, P.M., Harwood, D.M. 2002. Upper Cretaceous diatom biostratigraphy of the Arctic archipelago and northern continental margin, Canada. Micropaleontology. 48(4): 303-342. Tsoy I.B., Obrezkova M.S. 2017. Atlas of diatom algae and silicoflagellates from Holocene sediments of the Russian East Arctic seas. Vladivostok: POI FEB RAS. 146 p. Tsoy, I.B. 2001. Diatoms in surface sediments of the Siberian Arctic shelf (Laptev and East-
Vladivostok: Dalnauka. pp. 245-249.
RI PT
Siberian seas). Changes in the Atmosphere-land-sea system in the Amerasian Arctic.
Usoltseva, M., Khursevich, G. 2013. Alveolophora robusta comb. nov. from Miocene deposits of the
Vitim
Plateau,
Russia.
Diatom
28(1):
109-114.
DOI:
SC
10.1080/0269249X.2012.738251
Research.
Vinogradov, V., Goryachev, Y., Suprunenko, O. 2013. Laptev Sea as a possible base of effective
M AN U
development of oil and gas resources of Russian Arctic shelf. Drilling and Oil. 2. http://burneft.ru/archive/issues/2013-02/3
Winterfeld, M., Schirrmeister, L., Grigoriev, M. N., Kunitsky, V. V., Andreev, A., Murray, A., Overduin, P. P. 2011, Coastal permafrost landscape development since the Late Pleistocene in
AC C
EP
TE D
the western Laptev Sea, Siberia. Boreas, 10.1111/j.1502-3885.2011.00203.x. ISSN 0300-9483.