AMS 14C dating of the marine Holocene key section in Peter the Great Gulf, Sea of Japan

AMS 14C dating of the marine Holocene key section in Peter the Great Gulf, Sea of Japan

Nuclear Instruments and Methods in Physics Research B 223–224 (2004) 451–454 www.elsevier.com/locate/nimb AMS 14 C dating of the marine Holocene ke...

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Nuclear Instruments and Methods in Physics Research B 223–224 (2004) 451–454 www.elsevier.com/locate/nimb

AMS

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C dating of the marine Holocene key section in Peter the Great Gulf, Sea of Japan

Y.V. Kuzmin

a,*

, L.K. Levchuk b, G.S. Burr c, A.J.T. Jull

c

a b

Pacific Institute of Geography, Far Eastern Branch of the Russian Academy of Sciences, Radio St. 7, Vladivostok 690041, Russia Institute of Oil and Gas Geology, Siberian Branch of the Russian Academy of Sciences, Koptyug Ave. 3, Novosibirsk 630090, Russia c NSF-Arizona AMS Facility, Department of Physics, University of Arizona, Tucson, AZ 85721-0081, USA

Abstract A sediment core recovered from the vicinity of Vladivostok on Peter the Great Gulf (northwestern Sea of Japan coast), represents one of the most complete records of pollen, diatom and microfauna of the Holocene marine shallowwater sediments of this region. Until recently, there were no 14 C-dates on this core. Three bulk foraminifera samples were AMS 14 C-dated, and reservoir-corrected using R value as 370 yr. This allows us to pinpoint the most important Holocene climatic and oceanographic events in this part of the Sea of Japan, such as warm Tsushima current invasions. Ó 2004 Elsevier B.V. All rights reserved. PACS: 91.50 Keywords: AMS

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C dating; Foraminifera; Holocene; Paleoceanography; Peter the Great Gulf; Northwestern Pacific

1. Introduction Studies of the Holocene bottom deposits in Peter the Great Gulf (the northwestern Sea of Japan) started in the 1960s. As a result, a large amount of paleogeographical information for the Upper Pleistocene and Holocene was obtained from shelf cores [1], but radiometric control was insufficient. Peter the Great Gulf is a part of the Northwestern Pacific, located on the boundary between the subtropical and temperate water masses. Subtropical water mass originates from *

Corresponding author. Tel.: +7-4232-320-664; fax: +74232-312-159. E-mail address: [email protected] (Y.V. Kuzmin).

Tsushima current, one of the branches of warm Kuroshio current [2]. It has summer temperature 15–20 °C and salinity 33.5–34.0&; and winter temperature and salinity are 9–12 °C and 34.2– 34.5&, respectively. Another water mass in the northwestern Sea of Japan shelf originates in the Amur River mouth as the cold Shrenk current [2]; it has summer temperature 10–18 °C and salinity 26.0–33.5&; and winter temperature and salinity are 0.2–0.4 °C and 34.0&, respectively. Sea current fluctuations in the Holocene strongly affected local climate [3,4]. The age determination of main marine Holocene stratigraphic sub-divisions is an important task for the paleoenvironmental reconstructions in our studied area. However, few samples survived

0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.04.085

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after study of the cores drilled in the early 1970s was completed. With the help of AMS technique, we were able to measure the 14 C age of foraminifera stored in paleontological collections, to confirm or reject the sub-division of the key core 2 in the Peter the Great Gulf. The aim of this short report is to evaluate the previous paleoenvironmental reconstructions, mainly in terms of the 14 C age determination of major Holocene events, and to estimate general sedimentation rate throughout the Holocene in this area under consideration, which were not done before.

2. Material and methods Sediment core 2 in the vicinity of Vladivostok City (43° 110 N; 131° 520 E, water depth of 18 m; total length of 22 m) in Primorye (Maritime) Province of Russia, contains the most complete records of marine Holocene pollen, diatom and microfauna in the northwestern Sea of Japan area [5,6]. The total thickness of Holocene marine sediments, according to previous studies [6], is about 24 m. Three bulk foraminifera samples (about 2000 individual shells in each sample) were obtained for AMS 14 C dating from collection of Prof. T.S. Troitskaya. Foraminifera shells were converted to CO2 gas by hydrolysis of calcium carbonate with phosphoric acid, without cleaning of shells before hydrolysis. After completing of this step, about 0.1 mg of carbon was obtained for each sample. The d13 C values of the CO2 gas were measured on Fisons Optima mass spectrometer at the NSF-Arizona AMS Facility. The CO2 gas was converted to graphite by reduction with Zn, using Fe powder as a catalyst, according to routine procedure. The graphite produced was pressed into a target holder, which fits the carrousel of the AMS ion source. The NSF-Arizona AMS machine is 3MV NEC Pelletron, in operation since early 2000.

3. Results and discussion The following conventional 14 C dates according to [7] were obtained: (1) 1470 ± 100 yr BP

(AA-36614); depth 20.2 m; (2) 3765 ± 70 yr BP (AA-36615), depth 23.7 m; and (3) 8530 ± 160 yr BP (AA-36617), depth 31.7 m. 14 C reservoir correction age for the area was estimated to be 370 ± 26 yr [8]. The corrected 14 C values should correspond to the ‘‘terrestrial’’ ages of 1100, 3400 and 8160 yr BP, respectively. These 14 C values correspond to calibrated ages of 1050, 3660 and 9150 cal yr BP, respectively (using CALIB 4.3 software). The late Boreal period in core 2 is dated to 8200 yr BP. The estimated age of the Atlantic period, following the Boreal one, is 8000–5000 BP. The mid-Subboreal period is dated to 3400 yr BP, and the mid-Subatlantic period to 1100 yr BP (Fig. 1). Marine sedimentation started in the shallow part of Peter the Great Gulf (depth of 30 m) since the early Boreal period, 9000 yr BP, with a rate of 3.8 mm/yr during 9000–8000 yr BP. In the foraminifera assemblage, Ammonia neobeccarii neobeccarii, Cribroelphidium asterineus, C. goesi, Eggerella advena and Buliminella elegantissima dominate, and this reflects an environment of continuous marine transgression, with water depth close to modern one [5]. Diatom assemblage composition shows the beginning of marine environment [6]. Pollen data indicate that the vegetation of the surrounding shore was represented by birch-oak and oak forests, with admixture of broadleaved taxa such as elm (Ulmus) and nut-tree (Juglans) [6] (Fig. 1). All these data allow us to suggest that in the Boreal period climate was warmer than the present. Constant marine sedimentation continued after 8000 BP, with an average rate of 1.5 mm/yr since 8000 BP. Throughout the last 2000 yr, rate increased up to 3.5 mm/yr. In the foraminifera assemblage of the Atlantic period (8000–5000 BP), several species typical for subtropical water masses appeared for the first time: Dentalina ittai, Tappanella nipponica, Globulotuba entosoleniformis, Lagena mollis, L. gracilis, L. gracillima, L. semilineata, L. meridionalis, L. striata and Bulimina gibba [5]. The diatom assemblage shows the increase of salinity and water temperature [6]. Pollen data allow reconstructing the vegetation of rich broadleaved forests with oak, elm, nut-tree as dominant taxa, and with several thermophilous

Y.V. Kuzmin et al. / Nucl. Instr. and Meth. in Phys. Res. B 223–224 (2004) 451–454

Fig. 1. Composition of selected pollen taxa in core 2 (after [6], with additions) and

elements such as ash (Fraxinus) and hornbeam (Carpinus) [6]. Thus, during the Atlantic period environmental conditions in Peter the Great Gulf were the most warmest and humid throughout the Holocene. A branch of the warm Tsushima current affected the northwestern Sea of Japan coast, increasing water temperature and salinity. Several thermophilous mollusc species, such as Meretrix lusoria, Anadara subcrenata and A. inaequivalvis, with a northern habitat boundary today 500 km south of Vladivostok, penetrated to Peter the Great Gulf from the southern part of the Sea of Japan [9,10]. In the Subboreal period (4500–3000 BP), subtropical representatives disappeared from the foraminiferal assemblage [5]. In the diatom complex, amount of marine species decreased [6]. Oakbirch forests represented the vegetation of this time. These data show that during the Subboreal gradual cooling occurred. In the early Subatlantic period (2500–1100 BP), a significant cooling is recorded in the foraminiferal assemblage confirmed by the presence of subarctic species Globigerina pachyderma. In the late Subatlantic period, about 1100 BP, subtropical foraminifera species

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C ages of the foraminifera assemblages.

appeared again; oak forests represented vegetation of surrounding land with admixture of birch, and with some thermophilous taxa such as Juglans and Carpinus [6] (Fig. 1). The climate became warmer again; a new invasion of the Tsushima current branch is inferred. The intensity of the Tsushima current was less than during the Atlantic time (8000–5000 BP).

4. Conclusion Newly obtained 14 C data generally confirm the sub-division of the marine Holocene of southern Primorye, made on the basis of foraminifera, diatom and pollen data [6]. Southern Primorye throughout most of the Holocene was under influence of cold current from the northern part of the Sea of Japan. Two major invasions of the warm Tsushima current from south were detected and 14 C-dated, to 8000–5000 BP and 1100 BP. Warm current strongly affected local marine and terrestrial ecosystems; vegetation was represented by broadleaved forests with admixture of thermophilous species.

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Acknowledgements We are grateful to Prof. T.S. Troitskaya (Novosibirsk) for the possibility to use her foraminiferas’ collection (for sampling). This work was supported partly by the grant from US NSF (EAR01-154881). We are grateful to two anonymous reviewers for their comments. References [1] A.M. Korotky, L.P. Karaulova, T.S. Troitskaya, Chetvertichnye Otlozheniya Primorya (Quaternary Deposits of Primorye), Nauka, Novosibirsk, 1980. [2] G.I. Yurasov, V.G. Yarichin, Techeniya Yaponskogo Morya (The Currents of Japan Sea), Far Eastern

[3] [4] [5]

[6] [7] [8] [9]

[10]

Branch of the Russian Academy of Sciences, Vladivostok, 1991. K. Taira, K.A. Lutaenko, Rep. Taisetsuzan Inst. Sci. 28 (1993) 65. I. Koizumi, Diatom Res. 4 (1989) 55. T.S. Troitskaya, in: O.A. Betekhtina, I.T. Zhuravleva (Eds.), Sreda i Zhizn v Geologicheskom Proshlom (Environment and Life in the Geological Past), Nauka, Novosibirsk, 1974, p. 30. T.S. Troitskaya, L.P. Karaulova, E.I. Tsarko, Bull. Komissii Izucheniyu Chetvertich. Perioda 48 (1978) 66. M. Stuiver, H. Polach, Radiocarbon 19 (3) (1977) 355. Y.V. Kuzmin, G.S. Burr, A.J.T. Jull, Radiocarbon 43 (2A) (2001) 477. A.J.T. Jull, Y.V. Kuzmin, K.A. Lutaenko, L.A. Orlova, A.N. Popov, V.A. Rakov, L.D. Sulerzhitsky, Dokl. Biol. Sci. 339 (1994) 620. G.A. Jones, Y.V. Kuzmin, V.A. Rakov, Radiocarbon 38 (1) (1996) 58.