Search Results (3)

This study will review previously published Proto-Athabaskan (P-A) linguistic reconstructions related to weapons and ceramics technologies present on both sides of the Bering Strait. Na-Dene (N-D) is a large family of indigenous languages of North America, consisting mostly of the Athabaskan languages of the western interior, plus the Eyak and Tlingit languages of the southern Alaska coast. Athabaskan-Eyak (A-E) constitutes a distinct branch of Na-Dene. Dene-Yeniseian (D-Y) is a proposed transpacific family comprised of Na-Dene in addition to the Yeniseian languages of Siberia. Reconstructions pertaining to several specific technologies will be discussed in relation to likely cognates within broader A-E, N-D and D-Y historical contexts. Although D-Y is sometimes assumed to have originated near the conclusion of the Pleistocene Epoch (prior to ~11,500 years BP), this study will refocus fundamental questions on the current Holocene Epoch (after ~11,500 BP), and particularly the Late Holocene (after ~3000 BP). Full article

Inter-annual and seasonal variations of energy, vapor water, and carbon fluxes and associated climate variables in a middle taiga pine (Pinus sylvestris) forest on sandy soils and in a northern taiga larch (Larix gmelinii) forest on permafrost in central Siberia were studied from eddy covariance measurements acquired during the growing seasons of 1998–2000 and 2004–2008, respectively. Both the pure Scots pine of 215-year-old and pure Gmelin larch of 105-year-old forests naturally regenerated after forest fires, differed by their tree stand characteristics, and grew in extremely contrasting environments with distinctive climatic and soil conditions. Net radiation was greater in the pine forest due to higher values in the summer months and a longer growing season. Sensible heat flux was the larger term in the radiation balance in both forests. The Bowen ratio stayed between 1 and 2 during the growing season and was as high as 8–10 in dry spring in both forests. In the dry summers, latent heat explained 70%–80% of the daily net ecosystem CO₂ exchange (NEE) variation in both forests. The average NEE was significantly smaller in the larch ecosystem at −4 µmol m⁻²s⁻¹ compared to −7 µmol m⁻²s⁻¹ in the pine forest. NEP for the growing season was 83 in the larch forest on continuous permafrost and 228 g C m⁻² in the pine forest on warm sandy soils. Water use efficiency was 5.8 mg CO₂ g⁻¹H₂O in the larch forest and 11 mg CO₂ g⁻¹H₂O in the pine forest and appeared to be consistent with that in boreal forests. As a result of the forest structure change from Gmelin larch to Scots pine due to the permafrost retreat in a warming climate, the boreal forest C-sink may be expected to increase. Thus, potential feedback to the climate system in these “hot spots” of forest-forming replacement species may promote C-uptake from the atmosphere. However, as many studies suggest, in the pace of transition from permafrost to non-permafrost, C-sink would turn into C-source in hot spots of permafrost retreat. Full article

The Central Asian Orogenic Belt (CAOB) records multiple Phanerozoic tectonic events involving consolidation of disparate terranes and cratonic blocks and subsequent reactivation of Eurasia’s continental interior. The final amalgamation of the CAOB terrane collage involved diachronous closure of the Permian-Triassic Solonker suture in northernmost China and the Jurassic Mongol-Okhotsk suture in northeast Mongolia and eastern Siberia. The distribution, style, and kinematics of deformation associated with these two terminal collision events is poorly documented in southern Mongolia and northernmost China because these regions were later tectonically overprinted by widespread Cretaceous basin and range-style crustal extension and Miocene-recent sinistral transpressional mountain building. These younger events structurally compartmentalized the crust into uplifted crystalline basement blocks and intermontane basins. Consequently, widespread Cretaceous and Late Cenozoic clastic sedimentary deposits overlie older Permian-Jurassic sedimentary rocks in most basinal areas and obscure the deformation record associated with Permian-Triassic Solonker and Jurassic Mongol-Okhotsk collisional suturing. In this report, satellite image mapping of basinal compartments that expose folded Permian-Jurassic sedimentary successions that are unconformably overlapped by Cretaceous-Quaternary clastic sediments is presented for remote and poorly studied regions of southern Mongolia and two areas of the Beishan. The largest folds are tens of kilometers in strike length, east-west trending, and reveal north-south Late Jurassic shortening (present coordinates). Late Jurassic fold vergence is dominantly northerly in the southern Gobi Altai within a regional-scale fold-and-thrust belt. Local refolding of older Permian north-south trending folds is also evident in some areas. The folds identified and mapped in this study provide new evidence for the regional distribution and kinematics of Jurassic and Permian-Triassic contractional tectonism in the southern Mongolia-northern China borderland region. The newly mapped folds are also important potential targets for hydrocarbon exploration and vertebrate paleontological discoveries. Full article