Taphonomic phenomenon of ancient hair from Glacial Beringia: perspectives for palaeoecological reconstructions          下载免费PDF全文

Irina V. Kirillova  Johannes van der Plicht  Stanislav V. Gubin  Oksana G. Zanina  Olga F. Chernova  Elena G. Lapteva  Svetlana S. Trofimova  Eugeny V. Zinovyev  Anton A. Zharov  Elena O. Fadeeva  Thijs Van Kolfschoten  Fedor K. Shidlovskiy  Alexey A. Kotov 《Boreas: An International Journal of Quaternary Research》2016,45(3):455-469

An accumulation of mammoth hair, discovered in the Bol'shaya Chukochya River valley (northeast Yakutia, Russia), was found to contain remains of terrestrial and aquatic organisms, including plants, insects, crustaceans, birds and mammals. Radiocarbon dating indicated that this post‐mortem taphocoenosis represented multiple time periods. The mammoth hair was dated to older than 45 ka BP, the plants were dated to 12 750±50 a BP (which corresponds to a shift in the environmental conditions and landscapes during the formation of thermokarst in northeastern Russia) and the bird feathers were dated to 4115±40 a BP. A scenario of the formation of this fossil assemblage is proposed, covering the MIS 3‐1 time range. The hair also yielded various Arctic branchiopod crustaceans, which inhabit shallow temporary water bodies and therefore are important for reconstruction of palaeoenvironments. The cladoceran subgenus Daphnia (Ctenodaphnia), currently absent from the Asian part of Beringia, is reported from this region for the first time. The study demonstrates that the discovered permafrost‐preserved hair is a unique repository of Ice Age organisms.  相似文献   

Sedimentation of harmful dust by means of ultrasonic waves and additional disperse phase     

Sergey Titov  Maria Stepkina  Alexandra Antonnikova  Natalya Korovina  Boris Vorozhtsov  Eugeny Muravlev  Olga Kudryashova 《Arabian Journal of Geosciences》2015,8(12):11321-11328

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Deep sea circulation of particulate organic carbon in the Japan Sea     

Shigeyoshi Otosaka  Takayuki Tanaka  Orihiko Togawa  Hikaru Amano  Eugeny V. Karasev  Masayuki Minakawa  Shinichiro Noriki 《Journal of Oceanography》2008,64(6):911-923

Seasonal and spatial variations of particulate organic carbon (POC) flux were observed with sediment traps at three sites in the Japan Sea (western and eastern Japan Basin and Yamato Basin). In order to investigate the transport processes of POC, radiocarbon (¹⁴C) measurements were also carried out. Annual mean POC flux at 1 km depth was 30.7 mg m⁻²day⁻¹ in the western Japan Basin, 12.0 mg m⁻²day⁻¹ in the eastern Japan Basin and 23.8 mg m⁻²day⁻¹ in the Yamato Basin. At all stations, notably higher POC flux was observed in spring (March–May), indicating biological production and rapid sinking of POC in this season. Sinking POC in the high flux season showed modern Δ¹⁴C values (>0‰) and aged POC (Δ¹⁴C < −40‰) was observed in winter (December–January). The Δ¹⁴C values in sinking POC were negatively correlated with aluminum concentration, indicating that Δ¹⁴C is strongly related to the lateral supply of lithogenic materials. The Δ¹⁴C values also showed correlations with excess manganese (Mn_xs) concentrations in sinking particles. The Δ¹⁴C-Mn_xs relationship suggested that (1) the majority of the aged POC was advected by bottom currents and incorporated into sinking particles, and (2) some of the aged POC might be supplied from the sea surface at the trap site as part of terrestrial POC. From the difference in the Δ¹⁴C-Mn_xs relationships between the Japan Basin and the Yamato Basin, we consider that basin-scale transport processes of POC occur in the Japan Sea.  相似文献   

Midges of the genus Pseudodiamesa Goetghebuer (Diptera, Chironomidae): current knowledge and palaeoecological perspective     

Boris P. Ilyashuk  Elena A. Ilyashuk  Eugeny A. Makarchenko  Oliver Heiri 《Journal of Paleolimnology》2010,44(2):667-676

Larvae of the genus Pseudodiamesa Goetghebuer, which includes 12 described valid species and is divided by Makarchenko and Makarchenko (1999) into two species groups, Pseudodiamesa branickii group and Pseudodiamesa nivosa group, are widespread in lakes and running waters of cold, high-latitude and high-altitude areas of the Northern Hemisphere. Larval remains of the genus are often found in subfossil assemblages from these cold regions, but intra-genus morphotypes usually are not distinguished by palaeoecologists. Current knowledge of the ecology of the species indicates that the Pseudodiamesa nivosa group is more cold-adapted than the Pseudodiamesa branickii group and, therefore, these two intra-genus morphotypes cannot be amalgamated into a larger taxonomic unit without losing substantial information. Here we present the morphological characters of head capsules of Pseudodiamesa larvae attributed to the different species-group morphotypes, which are clearly visible in subfossil specimens. The information summarized in this paper will help provide more reliable chironomid-based palaeoclimatic inferences from lake sediment records covering colder phases through the late Quaternary in the Northern Hemisphere.  相似文献