Wrangel Island State Reserve, 686870 Ushakovskoye, Magadan Region, Russia
Kh. A. ARSLANOV, T. V. TERTYCHNAYA and S. B. CHERNOV
Geographical Research Institute, St. Petersburg State University, Sredniy Prospect 41, 199004 St. Petersburg, Russia
Abstract. Radiocarbon dating results of mammoth tusks, teeth and bones collected on Wrangel Island between 1989 and 1991 reveal a unique mammoth refugium during the Holocene. We used an improved chemical procedure to obtain and purify collagen from bone. Benzene synthesized from the samples was measured using a liquid scintillation counter. The validity of our data has been confirmed by the results of our measurements on two international control sample series (IAEA and TIRI) and by parallel measurements of Wrangel Island mammoth remains at other laboratories.
The last refugia of the mammoth were thought to be the Siberian Arctic and the Arctic islands, including Gydan and Taimyr Peninsulas and the Severnaya Zemlya Archipelago. The youngest 14C date our laboratory obtained for the Yuribei mammoth (Gydan peninsula, Siberia) was 10,000 ± 70 BP, based on stomach contents (plant debris). Similar results were later obtained by L. Sulerzhytsky (Geological Institute of the Russian Academy of Sciences, Moscow) for tusk and tooth remains of mammoths of the Taimyr Peninsula, Siberia (Lavrov and Sulerzhytsky 1992). 14C data thus indicated that mammoths became extinct, even in the refugia of the continental Siberian Arctic, ca. 9.7-10 ka ago. However, in 1990, our first five dates for mammoth remains from Wrangel Island were all of Holocene age, ranging from 7390-4740 BP (Vartanyan et al. 1992). This surprisingly young estimate prompted us to continue investigations at that location.
The Quaternary sediments of Wrangel Island are not very thick; they are primarily aleurite, sand, shingle and peat of Late Pleistocene and Holocene age. The coastal-marine sediments (in the Akademia Tundra) and the alluvium of the high terraces of large rivers, as well as the spare, heavily ice-bearing sand-shingle terraces of the lower hilly terrain, all seem to be of Pleistocene age. Numerous solifluction and other slope sediments of the mountainous part of the island, river-valley alluvium (floodplain and the first terraces of large rivers), and peat and lacustrine thermokarst sediments are widespread on the plains and intermontane depressions, and are of Holocene age.
Bone-rich horizons such as the "Edoma" strata in Siberia have not been found on Wrangel Island. All the bone specimens were collected from riverbed and slope sediments. Only well-preserved tusks (except for one split tusk), teeth and bones were collected. We selected teeth for dating from the collection of S. Vartanyan, made in 1991, which was previously studied by V. E. Garutt of the Zoological Institute of Russian Academy of Sciences.
We obtained carbon from the purified collagen by means of pyrolysis, then lithium carbide according to the reaction 2C + 2Li − Li2C2. Benzene synthesis was carried out using a high-efficiency vanadium-alumina-silica catalyst (V2O5 · Al2O3 · SiO2) that enabled us to produce benzene with up to 96% yield. Sample activity was measured with a coincidence scintillation counter using quartz spherical vials (8.46 ml capacity); background and modern standard count rates were 1.9 cpm and 56.8 cpm, respectively. Our techniques for pretreatment and measurement are described in detail elsewhere (Arslanov, Tertychnaya and Chernov 1993).
|Material and location||Lab no.||14C age
|Fragment of mammoth skin, Khatanga River, Taimyr Peninsula||LU-1057||>= 53,170|
|Plant debris from mammoth stomach, Yuribei River, Gydan Peninsula||LU-1153||10,000 ± 70|
|Mammoth tusk, Nizhnaya Taimyra River||GIN-1823||9670 ± 60|
|Mammoth tooth, Nizhnaya Taimyra River||GIN-1495||9860 ± 50|
|Mammoth tusk, October Revolution Island, Severnaya Zemlya Archipelago||LU-610||11,500 ± 60|
|Lab no.||Material, provenience||14C age
|Tusks and Bone|
|LU-2741||Tusk (8 cm diameter (d)) from the bed of the lower Neozhydannaya River||3730 ± 40||2192-2038|
|LU-2756||Tusk (11 cm d) from the bed of the lower Mamontovaya River||4400 ± 40||3082-2924|
|LU-2768||Tusk (9 cm d) from the bed of Tumanny Creek||4410 ± 50||3090-2924|
|LU-2556||Tibia bone (0.1-0.2 m) from the floodplain of the upper Lemmingovaya River||4740 ± 40||3626-3382|
|LU-2740||Tusk (6 cm d) from the bed of the lower Tundrovaya River||4900 ± 40||3706-3646|
|LU-2745||Tusk (9.5 cm d) from the bed of the lower Goosinaya River||5200 ± 30||4036-3972|
|LU-2744||Tusk from the bed of the middle Goosinaya River||5250 ± 40||4216-3990|
|LU-2742||Tusk from the bed of the lower Goosinaya River||5310 ± 90||4232-4000|
|LU-2535||Tusk from left bank of the Red Flag River valley, 2 km upstream from the mouth of the Otrozhnaya River||5480 ± 50||4440-4252|
|LU-2558||Tusk from diluvium-solifluction sediments on the western slope of Mount Kit, left side of Neizvestnaya River valley||6610 ± 50||5567-5450|
|LU-2736||Tusk from creekbed on the left side of the upper Neizvestnaya River valley||6760 ± 50||5666-5585|
|LU-2746||Tusk (7 cm d) from the bed of the lower Tundrovaya River||7040 ± 60||5954-5816|
|LU-2559||Tusk from the bed of middle Vetvisty Creek||7360 ± 50||6214-6062|
|LU-2444||Tusk from the right side of Red Flag River valley, area of the mouth of the Otrozhnaya River||7390 ± 30||6216-6176|
|LU-2798||Last upper molar from the bed of the lower Mamontovaya River (N-MAM-6)||4010 ± 50||2574-2464|
|LU-2808||Tooth fragment from the bed of the lower Mamontovaya River (N-MAM-2)||4040 ± 30||2582-2492|
|LU-2794||Last lower molar from the bed of the lower Mamontovaya River (N-MAM-5)||5110 ± 40||3966-3812|
|LU-2799||Last lower molar from the bed of the lower Goosinaya River (N-GUS-9)||6260 ± 50||5262-5088|
|LU-2810||Tooth fragment from the bed of the lower Goosinaya River (N-GUS-9)||6890 ± 50||5766-5672|
|LU-2809||Last lower molar from the bed of the upper Tundrovaya River||7250 ± 60||6158-5988|
|LU-2823||Last lower molar from the bed of the lower Goosinaya River (N-GUS-8)||12,010 ± 110||12,200-11,925|
|LU-2792||Last lower molar from the bed of the middle Red Flag River||12,980 ± 80||13,580-13,325|
|LU-2807||Last lower molar found on a beach, 1 km from the mouth of the Neizvestnaya River||20,000 ± 110||--|
Geomorphological reconstruction indicates that Wrangel Island formed a part of Beringia (an area that included Chukotka, Alaska, and the huge expanse of the surrounding shelf) during the Late Pleistocene, when the global sea level was ca. 100 m below the present level. At the end of the Pleistocene or beginning of the Holocene, Wrangel Island separated from the continent (Hopkins 1975), becoming a refugium for the mammoth population. Our data show that this population survived as long as 6000 yr after all mammoths on the continent were extinct. Morphological studies of mammoth teeth demonstrate that a previously unknown dwarf species of mammoth evolved on Wrangel Island (Vartanyan et al. 1993).
Three Wrangel Island mammoth teeth were found to be of Late Pleistocene age, with one sample (LU-2807) (Table 2) deriving from the period of the Late Glacial maximum (~20,000 BP). We obtained similar dates for a mammoth tusk collected on Severnaya Zemlya Archipelago (19,270 ± 130 BP) (Makeev, Arslanov and Garutt 1979), and for a front leg-bone found at the mouth of the Lena River, on the Bykovsky Peninsula (21,630 ± 240 BP, LU-1328, Tomirdiaro et al. 1984). All of these data support the thesis that during the last glacial maximum, conditions in the East-Siberian Arctic and on the northern islands were adequate for habitation by mammoths.
|TIRI code||Material||St. Petersburg measurements||TIRI mean values|
|A||Grain||117.02 ± 0.57%||116.12%|
|B||Wood||4580 ± 40 BP||4486 BP|
|C||Cellulose||129.27 ± 0.58%||129.81%|
|D||Peat||3730 ± 40 BP||3799 BP|
|E||Humic acid||10,980 ± 70 BP||11,066 BP|
|F||Iceland double spar||>= 50,000 BP||>= 46,076 BP|
|G||Wood||>= 51,560 BP||>= 42,962 BP|
|H||Peat||11,130 ± 40 BP||11,115 ± 116 BP|
|I||Travertine||11,170 ± 80 BP||11,034 ± 127 BP|
|J||Wood||1590 ± 40 BP||1593 ± 50 BP|
|K||Carbonate||18,400 ± 140 BP||18,166 ± 238 BP|
|L||Whalebone||12,580 ± 60 BP||12,605 ± 127 BP|
Later, 2 teeth and 1 tusk from Wrangel Island were dated at The University of Arizona Radiocarbon Laboratory (AA) (Long, Sher and Vartanyan 1994) and by L. Sulerzhitsky in the laboratory of the Geological Institute of the Russian Academy of Sciences (GIN). The data shown in Table 4 are in excellent agreement and, along with data from the Third International Radiocarbon Intercomparison (TIRI), these measurements confirm the reliability of our dates.
|Sample||Age and sample number|
|GUS-9, tooth||6260 ± 50, LU-2799||6360 ± 60, AA-11529|
|PIK-1, tooth||7250 ± 60, LU-2809||7295 ± 95, AA-11530|
|20-M, tusk||6760 ± 50, LU-2736||6750 ± 30, GIN-6990|
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