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1.
A. V. Lozhkin P. M. Anderson N. A. Goryachev P. S. Minyuk A. Yu. Pakhomov T. B. Solomatkina M. V. Cherepanova 《Doklady Earth Sciences》2010,430(2):198-200
Investigation of Pernatoe Lake sediments in the south of Paramushir Island has enabled us to obtain the first continuous pollen
record of climate and vegetation changes in the north of the Kurile archipelago during the Holocene. Series of radiocarbon
datings of between 10 000 ± 40 and 2180 ± 40 years ago are evidence that the beginning of sediments accumulation, found after
borehole development, is related to the Early Holocene. Diatom analysis has shown several stages in the lake development:
raised bog on the border of the Pleistocene and Holocene, lagoon formation resulting from the sea level rise over 9–6 ky,
and freshwater lake formation 6 ky and up to the present. Climate warming during the period attributed to the boreal and Atlantic
periods of the Holocene is reflected by the dominance of Pinus pumila and Alnus serrulata assemblages in vegetation cover. Wide dune fields were formed in the Sea of Okhotsk and the Pacific shores of Paramushir
Island 5–4 ky. Strengthening of atmogenic processes is related to cooling of the climate and drying of some areas of the underwater
slope. 相似文献
2.
A. V. Lozhkin P. M. Anderson T. V. Matrosova P. S. Minyuk J. Brigham-Grette M. Melles 《Russian Journal of Pacific Geology》2007,1(6):550-555
The comprehensive study of the upper 1283 cm of sediment from Lake El’gygytgyn, which formed nearly 4 Ma ago following a meteorite impact in northern Chukotka, yielded the first continuous record of the extreme changes in the Beringian climate and vegetation from the middle Middle Pleistocene to recent time (equivalent of marine isotope stages of 1–7 and the upper part of isotope stage 8). During this period, the climate was warmer than at present between 8600 and 10 7000 14C years and during the Late Pleistocene (isotope substage 5e, 116–128 ka ago). In 2003, the German-Russian-USA expedition continued studying sediments of Lake El’gygytgyn to obtain new evidence of the change in the vegetation cover in the Middle Pleistocene and the first information on the Middle Pleistocene interglacial (isotope stage 9; 297–347 ka ago). Pollen spectra characterizing the Middle Pleistocene interglacial are similar to spectra of the early stage of the Early Pleistocene interglacial and the climatic optimum in the Pleistocene to Holocene transitional period. The climatic history of Lake El’gygytgyn is basic for stratigraphic interpretations and correlations in the eastern sector of the Arctic. These data also expand our understanding of climatic changes that are studied within the framework of the “Pole-Equator-Pole Paleoclimate,” “Past Global Changes,” and other international projects. 相似文献
3.
Major and trace element distribution in the bottom sediments from Hole 13 drilled in Lake Grand, Magadan district, was studied using the method of principal components. It was established that geochemical characteristics are correlated with environmental changes. The sediments of cold MIS2 and MIS4 are characterized by the enriched TiO2, MgO, Al2O3, Fe2O3, and Cr and low Na2O, K2O contents, which is related to the grain-size composition of sediments. Sediments of warm stages show an opposite tendency. High concentration peaks of iron, phosphorus, and manganese correspond to the accumulation levels of vivianite and ferromanganese rocks. Silica is represented by biogenic and abiogenic varieties. Maximum SiO2 contents were found in the Late Holocene sediments and mark the high biological productivity of the basin. Revealed variations of some elements are correlated with the Heinrich events. 相似文献
4.
Early-Middle Pleistocene deposits have been studied in Central and Northern Yakutia, the Magadan region, and Chukotka. The Brunhes-Matuyama boundary occurs in the Ozheleznenye Galechniki (=Ferruginated pebblestones) beds of Central Yakutia that belong to the Talagay horizon of the Early-Middle Pleistocene. These layers include classic Aldan mammal fauna. In Eastern Yakutia sediments of Early-Middle Pleistocene belong to the Akan horizon, and the Early Pleistocene sediments are from the Chukochya horizon. These sediments which belong to the Olyor Formation and its age-equivalents yielded numerous mammal remains, termed the Olyor faunal complex. The Brunhes-Matuyama boundary is located in Akan horizon. In the upper reaches of the Kolyma River, the Brunhes-Matuyama boundary occurs in sediments of the Middle Pleistocene Belichan horizon. The boundary of the Brunhes-Matuyama is characteristic within the Elhkakvun and Enmakay formations of Chukotka. In Kamchatka, the boundary of Matuyama and Brunhes is evident in volcanic sequences. In the eastern part of the peninsula, this boundary is located in the Tumrok or Iult volcanic complex and in Central Kamchatka in the Kreruk volcanic complex. 相似文献
5.
A. V. Lozhkin P. M. Anderson T. V. Matrosova P. S. Minyuk 《Journal of Paleolimnology》2007,37(1):135-153
Three types of pollen assemblages (shrub-dominated, mixed herb- and shrub-dominated, and herb-dominated) characterize the
~ 300,000 year palynological record from El’gygytgyn Lake. Despite major changes in global climatic forcings, all pollen spectra,
with a few isolated exceptions, have strong to possible analogs in the modern plant communities of Northeast Siberia and Alaska.
Paleoclimatic reconstructions based on squared chord-distance analog analyses indicate two periods (~8600–10,700 14C year B.P. and OIS 5e) when summers were perhaps ~2 to 4°C warmer than modern. January temperatures were also warmer than
present, and both July and January were wetter than today. Palynological data remain inconclusive as to the establishment
of forests near El’gygytgyn Lake at these times. The wettest Julys occurred during OIS 5 d. July temperatures were near modern,
and Januarys were colder and drier than now. January temperatures, even into the Middle Pleistocene, generally show little
variability, suggesting that the suppression of arboreal taxa during glaciations was likely caused by cool summers with low
effective moisture and not by frigid winters. Because age schemes that correlate magnetic susceptibility to variations in
summer insolation or ∂18O have cool plant taxa persisting in warm times (and vice versa), we propose an alternative age model based on the palynological
data.
Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .
This is the first in a series of eleven papers published in this special issue dedicated to initial studies of El’gygytgyn Crater Lake and
its catchment in NE Russia. Julie Brigham-Grette, Martin Melles, Pavel Minyuk were guest editors of this special issue. 相似文献
6.
This paper presents data on the inorganic geochemical characteristics of the sediments from Hole LZ1024 (Lake El’gygytgyn,
Chukotka, 67°30′ N 172°08′ E). It is demonstrated how these data are associated with climatic variations during isotope stages
1–9. The sediments of the warm stages are characterized by elevated contents of SiO2, CaO, Na2O, K2O, and Sr and low concentrations of TiO2, Al2O3, MgO, and Fe2O3. It has been established that the geochemical parameters correlate with global climatic variations. 相似文献
7.
8.
P. S. Minyuk T. V. Subbotnikova A. A. Plyashkevich 《Izvestiya Physics of the Solid Earth》2011,47(9):762-774
Magnetic susceptibility (MS) of natural specimens of hematite and goethite is studied under continuous heating with various
additives: with carbon (sugar), nitrogen (carbamide), and elemental sulfur. It is found that heating of hematite with carbon
above 450°C results in the formation of single-domain magnetite, while the magnetic susceptibility rises by a factor of 165.
The increase in magnetic susceptibility on heating of hematite with nitrogen above 540°C reflects the generation of a single-domain
maghemite with the Curie point of about 650°C, which is stable to heating. After the first heating, the magnetic susceptibility
increases by 415 times. The subsequent cycle of thermal treatment results in the transition of maghemite to hematite, a decrease
of MS, and an increase of coercivity. Heating with sulfur produces a stable single-domain magnetite at a temperature above
the Curie point, which is manifested in the cooling curves. Here, the MS increases by a factor of 400. The heating curves
for goethite exhibit a sharp drop in susceptibility to a temperature of 350–360°C, which reflects the transition of hematite
to goethite. Heating of hematite with carbon produces stable maghemite at above 530°C, and with sulphur and nitrogen, it produces
magnetite. When heated with pyrite, hematite reduces to magnetite under the action of sulfur released from pyrite. 相似文献
9.
P. S. Minyuk T. V. Subbotnikova P. M. Anderson A. V. Lozhkin 《Izvestiya Physics of the Solid Earth》2013,49(1):120-129
Lake Pernatoe is located on Paramushir Island, Kuril Arc, in the area of sand dunes. The 7-m-thick sediments of this lake pertain to the Holocene and contain palustrine, marine, and lacustrine facies. The rock magnetic properties of the sediments are analyzed for tracking the changes in sedimentation conditions. Marine facies are noted with low content of magnetic minerals; their magnetization is dominated by the paramagnetic component; pseudo-single-domain particles of magnetic material and iron sulfides (pyrite) are present. Pyrite frequently occurs in diatoms in the form of chains, spherules, and crystals. The lacustrine facies show high values of the magnetic parameters; they contain multidomain particles, mostly titanomagnetite and magnetite. Sands and sandy silts have the maximum values of magnetic parameters and reflect the stages of aeolian activity, corresponding to climatic cooling and marine regressions. On the basis of magnetic properties, four stages of active aeolian sedimentation are identified in the Holocene. 相似文献
10.
Julie Brigham-Grette Martin Melles Pavel Minyuk Scientific Party 《Journal of Paleolimnology》2007,37(1):1-16
Sediment piston cores from Lake El’gygytgyn (67°N, 172°E), a 3.6 million year old meteorite impact crater in northeastern
Siberia, have been analyzed to extract a multi-proxy millennial-scale climate record extending to nearly 250 ka, with distinct
fluctuations in sedimentological, physical, biochemical, and paleoecological parameters. Five major themes emerge from this
research. First the pilot cores and seismic data show that El’gygytygn Crater Lake contains what is expected to be the longest,
most continuous terrestrial record of past climate change in the entire Arctic back to the time of impact. Second, processes
operating in the El’gygytygn basin lead to changes in the limnogeology and the biogeochemistry that reflect robust changes
in the regional climate and paleoecology over a large part of the western Arctic. Third, the magnetic susceptibility and other
proxies record numerous rapid change events. The recovered lake sediment contains both the best-resolved record of the last
interglacial and the longest terrestrial record of millennial scale climate change in the Arctic, yielding a high fidelity
multi-proxy record extending nearly 150,000 years beyond what has been obtained from the Greenland Ice Sheet. Fourth, the
potential for evaluating teleconnections under different mean climate states is high. Despite the heterogeneous nature of
recent Arctic climate change, millennial scale climate events in the North Atlantic/Greenland region are recorded in the most
distal regions of the Arctic under variable boundary conditions. Finally, deep drilling of the complete depositional record
in Lake El’gygytgyn will offer new insights and, perhaps, surprises into the late Cenozoic evolution of Arctic climate.
This is the first in a series of eleven papers published in
this special issue dedicated to initial studies of El'gygytgyn
Crater Lake and its catchment in NE Russia. Julie Brigham-Grette, Martin Melles, Pavel Minyuk were guest
editors of this special issue. 相似文献