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ISSN 1028-334X, Doklady Earth Sciences, 2008, Vol. 421A, No. 6, pp. 961–964. © Pleiades Publishing, Ltd., 2008.Original Russian Text © E.L. Goldberg, M.A. Phedorin, E.P. Chebykin, O.M. Khlystov, N.A. Zhuchenko, 2008, published in Doklady Akademii Nauk, 2008, Vol. 421, No. 4,pp. 542–545.

Records of climatic changes obtained in Greenlandand Arctic ice [1–4] with year–decade resolution havealso stimulated investigations with a similar resolutionfor other climatic archives, such as sediments of lakesand bogs. Such a high resolution is needed for thedetection of abrupt climatic changes in differentregions of the planet. Sudden and short warming andcooling (Dansgaard–Oeschger, D/O) events show upmost clearly in isotope records from Greenland ice dur-ing the Last Glaciation 15–74 ka BP [1–4]. In thecourse of such events, the temperature over Greenlandsuddenly rose by 10–15

°

C in just 10–50 yr and fellnearly in a similar manner to the initial state in 400–1000 yr [1–4]. Not only did the temperature changedramatically, but humidity on the continent alsochanged synchronously, since almost all the D/O peakswere accompanied by a synchronous abrupt increase inthe atmospheric content of methane, which is generatedin the course of bog formation and expansion [3]. Sim-ilar abrupt climatic events synchronous with those inGreenland were also revealed in other regions of theNorthern Hemisphere [5].

The purpose of this work is to search for theresponse of East Siberia to fast climatic changes in theNorth Atlantic over the last 150 ka. We adduce heregeochemical evidence of episodes of abrupt climatehumidification in the Baikal drainage basin (BDB) dur-

ing the Last Glaciation, which were synchronous withthe D/O events in Greenland.

We studied sediments from Lake Baikal taken on theslope of the Akademichesky Range, which separatesthe northern and central basins of the lake. Three coreswere recovered at nearly one site

(53°33

′

04

′′

N,

107°54

′

53

′′

E). Coeval levels of the cores were identi-fied using data of high-resolution analysis of diatomassemblages and profiles of sediment humidity and bio-genic silica. A composite core from Station 2 was pre-viously examined for uranium isotopes and dated bythe

230

Th/

234

U

method [6]. In the present communica-tion, we present the data on the continuous scanningelement analysis of sediments in the composite corerecovered at the same station. The composite core is750 cm long, in which the first core spans the intervalof 0–100 ka and the second core spans the interval of80–150 ka.

The contents of elements were determined by scan-ning X-ray fluorescence analysis with synchrotron radi-ation (SRXRF) from the VEPP-3 accelerator (SR facil-ity of the Institute of Nuclear Physics, Novosibirsk) [7, 8].The vertical aperture of the SR beam and the scanningstep were 1 mm. Such laboratory conditions provided acontinuous record of concentrations of elements in thesediment core with a 1-mm spatial resolution. Therecord is represented by 7500 levels, and the averagetemporal resolution is ~20 yr. Sediment samples (slabs18–28 cm long, 1.5–2.0 cm wide, and 5–8 mm thick)were cut out from the axial part of the core. As previ-ously described in [7, 8], the SRXRF analysis was car-ried out directly on wet sediment samples wrapped witha thin envelope.

The diatom abundance, biogenic silica content, sed-iment water content, and uranium isotopes were mea-sured with a step of 1.0 cm [6]. An age model of thestudied core was obtained by its correlation with theadjacent cores [6, 9] previously dated by the

234

U/

230

Th

The Decade-Resolved Record of the Response of East Siberiato Abrupt Climatic Changes in the North Atlantic

over the Last Glacial–Interglacial Cycle

E. L. Goldberg

a, b

, M. A. Phedorin

a, c

, E. P. Chebykin

a

, O. M. Khlystov

a

, and N. A. Zhuchenko

a

Presented by Academician M.A. Grachev May 21, 2007

Received May 29, 2007

DOI:

10.1134/S1028334X08060226

a

Limnological Institute, Siberian Branch, Russian Academy of Sciences, ul. Ulan-Batorskaya 3, Irkutsk, 664033 Russia; e-mail: gold@econova.nsk.su

b

Institute of Archeology and Ethnography, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent’eva 17, Novosibirsk, 630090 Russia

c

Institute of Petroleum Geology and Geophysics, Siberian Branch, Russian Academy of Sciences,pr. akademika Koptyuga 3, Novosibirsk, 63090 Russia

GEOGRAPHY

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method. We also used the La Shamp event date (41.2 ka)based on the position of the cosmogenic

10

Be peak andthe Bölling–Alleröd (B/A) event (14.6 ka) confined tothe peak of the

St. flabelatus

diatom abundance [6].

RESULTS AND DISCUSSION

The trends of element contents show that clastoge-nic elements K, Ti, Zn, Rb, Sr, Zr, Y, Nb, Th, Cs, La,and Ce form cluster 1 with the correlation coefficientbetween records varying from 0.78 to 0.92. One canalso clearly distinguish cluster 2 with U, Br, I, Sr/Rb,Ca/K, and BiSi (biogenic silica) and cluster 3 with Mn,Fe, As, and Mo. Temporal trends of clusters 2 and 3 areantithetical relative to trends of cluster 1. A similar sit-uation was also observed for element records of Baikalsediments on the orbital scale for the last 1 Ma [7, 10].Warm (and/or humid) periods are characterized byBiSi, U, Br, I, Sr/Rb, Ca/K, and Cu/Zn peaks; coolingand glacial periods, by decrease in the content of ele-ments of this group, an abrupt increase in the content ofclastogenic elements, and a high La(Ce)/Yb(Y) ratio inthe sediment. Such behavior is related to a climaticallymodulated change of provenances, which delivered com-positionally different suspended particulates to the lake.We believe that chemically weathered particulates weredelivered to the lake from the BDB by rivers in humid andwarm periods. During cold and extremely arid periodswhen the river runoff was very weak [11], the particulateswere delivered mainly by the “glacial milk” formed due tothe physical weathering of underlying rocks.

Figure 1 demonstrates the comparison of high-reso-lution indicator records for the last 150 ka with globalclimatic records (the temperature over Greenland ver-sus the volume of global ice sheets). The stack of clas-togenic elements (K, Ti, Rb, and Nb) represents anaverage normalized depth–age profile of these elements[7, 10]. Stack minimums characterize periods ofintense fluvial inflow of particles into the lake from theBDB plain. As shown above, the minimums correspondto warm (and/or humid) periods in East Siberia [7, 10].Another independent climate indicator in the BDB isthe Sr/Rb ratio in sediments [7, 10]. Peaks of the Sr/Rbratio in sediments are confined to climate warming,humidification of the drainage basin, intense chemical

weathering of feldspars and carbonates, and probableprecipitation of authigenic phosphates [7, 10]. As isevident from Fig. 1, the axes of all indicators aredirected in such a way that their peaks point to thedirection of warming and/or moistening (the right thickline). It is clear from the figure that the BDB is verysensitive both to global warming–glaciation events onthe orbital scale and to abrupt and short-term climaticevents recorded in the North Atlantic and Greenland(D/O events). Most of these climatic events are syn-chronous within the errors of our absolute

230

Th–

234

Udepth–age scale.

It is also seen in Figs. 1a and 1d that all warmingsubstages of the marine isotope stage (MIS) in EastSiberia, which corresponded to MIS 5.1, MIS 5.3, andMIS 5.5 (Kazantsev Interglacial in Siberia), were inter-rupted by marked cooling events. None of the substages(Figs. 1a, 1d), which match precession insolation max-imums in Fig. 1c showing variation in the global icesheet volume (

δ

18

O

in benthic foraminifers), is repre-sented by a single peak in the record. Instead, they arealways represented by a doublet or triplet. Let us notethat the abrupt cooling episodes (and/or changes inaridity) observed in Siberia correlate with synchronouscooling events in Europe: the Middle Eemian cooling(~122–124 ka BP) and the Montaigu event (the Mon-taigu event in Europe and the C23 event [12, 13] ~102–104 ka BP in the Atlantic). The warm substage MIS 5.1(73.9–85.0 ka BP) also included several abrupt coolingepisodes (C events) in North Atlantic waters [12, 13].All these episodes are also clearly traced in the Baikalrecord as well (Figs. 1a, 1d).

We should emphasize the clear response of EastSiberia to D/O events (D/O 4–17), which was bestexpressed during the Karga warming episode in Siberia(the MIS 3 analog, 24–59 ka BP). Two triplet–quartetevents (D/O 6–8 and D/O 9–12) characteristic of this inter-val are clearly distinguished in records of Lake Baikal.A repeated scanning of the area (~27–52 ka BP) carriedout with the archive half portion of the core reproducedcompletely all details observed in Fig. 1d (not shown inthe present paper).

Several series of similar triplets of nearly the sameage were revealed earlier in records of C/N,

δ

13

ë

of thetotal organic carbon, and diatom abundance in sedi-

Fig. 1.

A high-resolution record of the BDB response to abrupt climatic changes in the North Atlantic and Greenland. Record res-olution ~20 yr. Legend for the upper panel: (a) stack of clastogenic concentrations of elements in sediments; (b) diatom abundancein sediments [6] on the logarithmic scale; (c) the volume of global ice sheets. Thick dotted lines denote terminations I (11.5 ka)and II (130 ka). Gray boxes designate warm periods (odd MIS). Legend for the lower panel: (d) the Sr/Rb ratio record in sedi-ments—an indicator of warm periods for the BDB [7, 10]; (e) indicator of air temperature over Greenland (

δ

18

O

of ice [1–14]) withthe D/O events indicated below. Correlative levels in Greenland and Lake Baikal are shown by thin dotted lines in the lower panel.Numbers of Greenland D/O events correlated with the Baikal events are given at the top. Correlative peaks (or their groups) areshown by long arrows at the top. Short arrows at the top denote short climatic reversal episodes in the BDB during warm substagesof MIS 5. Dotted arrows designate cooling events in Europe: the Montaigu event (~104 ka BP, MIS 5.3), the Middle Eemian event(~124 ka BP, MIS 5.5), and C21a cooling event in the Atlantic (~82–84 ka BP, MIS 5.1 [13]). Arrows in the Greenland scale (lowerpanel) denote short-term but substantial water cooling events (C events) in the North Atlantic: C21–C25 [12, 13] (C21 and C24correspond to substantial cooling events in Europe (Melisey-1 and Melisey-2), which correlate with MIS 5.2 and MIS 5.4, respec-tively. The box in (d) designates the interval scanned twice. All the records are shown on their own time scales.

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50 100 1500Age, ka

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ments of Core BDP-93 [14, 15]. The indicators sug-gested an intense removal of soil carbonates from thedrainage area and an increase in river runoff (i.e.,humidification) during the deposition of these sedimen-tary layers. The authors of [14, 15] recognized theseevents as “Kuz’min events” and correlated them withHeinrich events (H events) [4].

However, it is known that H events accompanied thecoldest episodes in the Atlantic [1–4] when an oceanicheat conveyor driven by thermohaline circulationmoved from the Northern to Southern Hemisphere [3].Such conditions could hardly facilitate the evaporationof water in the Atlantic and the transport of moisture toEast Siberia by western winds, development of vegeta-tion in the BDB, and increase in river runoff. Webelieve that abrupt climate warming and humidificationin Siberia were related to warm phases of D/O events(Figs. 1a, 1d). It is known that warm phases (periods) ofD/O events were characterized not only by short-termwarming episodes [1–5], but also by the simultaneousgeneral humidification on continents during the globalarid glacial climate. This process is recorded in the iceof Greenland and Antarctica by the synchronous posi-tions of the atmospheric methane peaks and D/Oevents, indicating a short-term expansion of bogs dur-ing these periods [3]. Under such conditions, it wouldbe reasonable to expect short periods of river runoffintensification during global arid climate of glaciation.It is worth noting that, during the longest and most sub-stantial warming episodes in Greenland (D/O 6–12),diatoms could appear in the Baikal pelagic zone anddevelop even under glacial-type conditions (Fig. 1b).Although the diatom abundance was three to fourorders of magnitude lower than present-day values(Fig. 1b), the very fact of their appearance during thelongest D/O events [7] is important. In conclusion, letus note the following point: the general increasing trendof Lake Baikal records from MIS 4 to MIS 2 (Fig. 1)suggests that the climate at the MIS 4 stage of glacia-tion in Siberia was more arid relative to the MIS 2 stage(the Sartan Glaciation in Siberia).

ACKNOWLEDGMENTSWe are grateful to K.B. Zolotarev, E.G. Miginskaya,

V.M. Tsukanov, and V.I. Kondrat’ev (researchers withthe SI Facility at the Institute of Nuclear Physics,

Novosibirsk) for their assistance in carrying out exper-iments, as well as academicians M.A. Grachev andG.N. Kulipanov for their constant support.

This work was supported by the Russian Foundationfor Basic Research (project nos. 06-05-91576-YaF and08-05-98071-Siberia) and the Presidium of the RussianAcademy of Sciences (program no. 16.8).

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