807 research outputs found
Paleomagnetism of Quaternary sediments from Lomonosov Ridge and Yermak Plateau: implications for age models in the Arctic Ocean
No full textInclination patterns of natural remanent magnetization (NRM) in Quaternary sediment cores from the Arctic Ocean have been widely used for stratigraphic correlation and the construction of age models, however, shallow and negative NRM inclinations in sediments deposited during the Brunhes Chron in the Arctic Ocean appear to have a partly diagenetic origin. Rock magnetic and mineralogical studies demonstrate the presence of titanomagnetite and titanomaghemite. Thermal demagnetization of the NRM indicates that shallow and negative inclination components are largely “unblocked” below ?300 °C, consistent with a titanomaghemite remanence carrier. Following earlier studies on the Mendeleev–Alpha Ridge, shallow and negative NRM inclination intervals in cores from the Lomonosov Ridge and Yermak Plateau are attributed to partial self-reversed chemical remanent magnetization (CRM) carried by titanomaghemite formed during seafloor oxidation of host (detrital) titanomagnetite grains. Distortion of paleomagnetic records due to seafloor maghemitization appears to be especially important in the perennially ice covered western (Mendeleev–Alpha Ridge) and central Arctic Ocean (Lomonosov Ridge) and, to a lesser extent, near the ice edge (Yermak Plateau). On the Yermak Plateau, magnetic grain size parameters mimic the global benthic oxygen isotope record back to at least marine isotope stage 6, implying that magnetic grain size is sensitive to glacial–interglacial changes in bottom-current velocity and/or detrital provenance
A semiotic analysis of the short stories of Leonid Andreyev, 1900-1909
No full textThis thesis applies the techniques of semiotic analysis to a selection of short stories by Leonid Andreyev in an attempt to offer one answer to the problems of categorising Andreyev's unique art and placing it within a literary-evolutionary perspective. The semiotic method was chosen because of its ability both to assimilate literary texts to the supra-individual processes with which it works, and at the same time to delineate an author's particular contribution to these processes. Drawing on a range of literary theory from early Russian Formalism onwards, the study proceeds from one level to another according to a principle of "degree of abstraction", so that each level constitutes firstly an independent account of Andreyev's texts in itself, and secondly one stage in an overall analysis. The analysis at each level pinpoints, in its own terms, a series of semiotic tensions or clashes as being at the heart of Andreyev's literary system. Conflict within his stories between the principles of poetry and prose, metaphor and metonymy, 'discourse' and 'story' and between codes of allegory and codes of reference are among the major tensions highlighted. These tensions are in turn used to account for the fantastic element in Andreyev's stories (tension and ambiguity being the key features of Fantastic literature as defined by many literary theoreticians).The unique, Andreyevan version of the Fantastic is viewed as an index of Andreyev's position in literary evolution at a point of transition between an older, authoritative, transitive mode of narration and a more recent, non-authoritative mode which has come to dominate much twentieth-century literature. The final reference-point for all these tensions is demonstrated to be a shift in modern culture as a whole towards a more impersonal. Mythic thought-system, a shift at the centre of which the art of Leonid Andreyev can be convincingly placed. The material drawn upon includes, in addition to the corpus of Andreyev stories specified, a wide range of works by Andreyev's contemporaries and also the hitherto unexploited draft-manuscripts to a number of Andreyev stories held in the Hoover Institution, U.S.A.A Glossary of the most commonly used theoretical terms is provided at the end of the study
Dating late Quaternary planktonic foraminifer Neogloboquadrina pachyderma from the Arctic Ocean using amino acid racemization
No full textThe long-term rate of racemization for amino acids preserved in planktonic foraminifera was determined by using independently dated sediment cores from the Arctic Ocean. The racemization rates for aspartic acid (Asp) and glutamic acid (Glu) in the common taxon, Neogloboquadrina pachyderma, were calibrated for the last 150 ka using 14C ages and the emerging Quaternary chronostratigraphy of Arctic Ocean sediments. An analysis of errors indicates realistic age uncertainties of about ±12% for Asp and ±17% for Glu. Fifty individual tests are sufficient to analyze multiple subsamples, identify outliers, and derive robust sample mean values. The new age equation can be applied to verify and refine age models for sediment cores elsewhere in the Arctic Ocean, a critical region for understanding the dynamics of global climate change
Plio-Pleistocene sedimentary record from the Northwind Ridge: new insights into paleoclimatic evolution of the western Arctic Ocean for the last 5 Ma
No full textSediment core HLY0503-03JPC from the top of the Northwind Ridge provides the first confirmed Plio-Pleistocene record from the western Arctic Ocean, with calcareous microfossils uniquely preserved to ca. 5 Ma. Results are compared to nearby core P1-93AR-P23 from the ridge slope, which was previously used to reconstruct early Quaternary sea-ice conditions in the region (Polyak et al. in Quat Sci Rev 79:145–156, 2013), and is now re-dated to at least the late Pliocene. Ages were estimated primarily from strontium isotope stratigraphy on benthic foraminifers. Based on multiple physical, paleomagnetic, elemental geochemical, and paleobiological (foraminifers) proxies, we identify three major stratigraphic divisions (Units 1, 2a, and 2b) roughly representing upper to middle (“glacial”) Quaternary, lower Quaternary to Pliocene, and lower Pliocene to possibly upper Miocene (undated). Benthic foraminiferal assemblages were utilized to evaluate paleo-sea-ice conditions, while other proxies were used to interpret paleocirculation and sediment transport processes. Early Quaternary and older sediments indicate diminutive effect from glaciations, reduced sea-ice conditions, and a periodic strong current impact on the ridge top, possibly due to an enhanced Atlantic water flow. Ages derived from the first foraminiferal tests appearing at ca. 5 Ma likely indicate a redeposition pulse that we attribute to the onset of Pacific water throughflow via the Bering Strait. A large hiatus above this level in JPC3 spans most of the Pliocene. The Unit 2a/1 boundary, estimated to ca. 0.8 Ma, is marked by an abrupt faunal and sedimentary change, which is consistent with the major climatic shift that occurred during this time (Mid-Pleistocene Transition). Unit 1 exhibits a strong control from glacial cyclicity, with a progressive expansion of the Laurentide Ice Sheet primarily affecting the study region, and mostly perennial sea-ice conditions. Overall results suggest that the Pliocene and early Pleistocene may provide relevant paleoclimatic analogs for the rapidly changing Arctic environments of today
Study of Core 92AR-P25 from the Northwind Ridge, Central Arctic Ocean
No full textThe Arctic Ocean is presently the least understood ocean in the world. The
perennial sea ice that covers most of the Arctic has hindered exploration and
interpretation of this last remaining portion of the Earth’s surface. The geologic history of this ocean is not fully understood and needs to be studied in greater detail. The stratigraphic record in the Arctic is a topic of much debate, specifically when discussing
ages and sedimentation rates. Various ways of age dating has shed new light on ages and
sedimentation rates of the established stratigraphy. Proxies such as microfossils and isotope evidence are giving us new insights to the paleoceanography of the Arctic Ocean basin. Core 92AR-P25 from the Northwind Ridge shows correlation with the
paleomagnetic time scale and agreement with the manganese color cycles proposed by
Jakobsson et al, (2000). The correlation of the core, shows that many cores throughout
the Central Arctic Ocean can be similarly correlated, allowing us to form a
paleoceanography history of the Arctic Ocean
Quaternary foraminiferal data from western Arctic Ocean sediment cores, 2013-2016
No full textData reported for downcore distribution of foraminifers in three sediment cores distributed across the western Arctic Ocean (Northwind, Mendeleev, and Lomonosov Ridges). Data include total numbers for benthic and planktic foraminifers and identification of benthic species. The purpose of the data is to characterize stratigraphic changes in foraminiferal assemblages as proxies for sedimentary environments. This investigation provides insights into middle to late Pleistocene history of Arctic paleoceanographic and sea-ice conditions on multi-millennial time scales. Calcareous foraminiferal abundances and composition show stratigraphically consistent development, including glacial–interglacial variability and long-term evolution of foraminiferal assemblages. The long-term trend shows notably a diminishing role of phytodetritus-related species indicative of ice-margin proximity at the expense of oligotrophic species adapted to live under persistent sea ice. These changes presumably indicate an overall expansion of year-round ice cover in the Arctic during the Pleistocene. Data is reformatted from Lazar, K.M., Polyak, L., 2016. Middle to late Pleistocene benthic foraminifers in the Arctic Ocean: implications for sea-ice and circulation history. Marine Micropaleontology 126, 19-30
Quaternary foraminiferal data from western Arctic Ocean sediment cores, 2013-2016
No full textData reported for downcore distribution of foraminifers in three sediment cores distributed across the western Arctic Ocean (Northwind, Mendeleev, and Lomonosov Ridges). Data include total numbers for benthic and planktic foraminifers and identification of benthic species. The purpose of the data is to characterize stratigraphic changes in foraminiferal assemblages as proxies for sedimentary environments. This investigation provides insights into middle to late Pleistocene history of Arctic paleoceanographic and sea-ice conditions on multi-millennial time scales. Calcareous foraminiferal abundances and composition show stratigraphically consistent development, including glacial–interglacial variability and long-term evolution of foraminiferal assemblages. The long-term trend shows notably a diminishing role of phytodetritus-related species indicative of ice-margin proximity at the expense of oligotrophic species adapted to live under persistent sea ice. These changes presumably indicate an overall expansion of year-round ice cover in the Arctic during the Pleistocene. Data is reformatted from Lazar, K.M., Polyak, L., 2016. Middle to late Pleistocene benthic foraminifers in the Arctic Ocean: implications for sea-ice and circulation history. Marine Micropaleontology 126, 19-30
Correlation of sediment core characteristics from Mendeleev Ridge, Central Arctic Ocean
No full textOcean sediment cores can provide key information on timing and nature of climate events. Two ocean sediment cores from Mendeleev Ridge, Arctic Ocean, one of which has been previously studied and dated with absolute age dating techniques, are compared for various attributes, notably color, biogenic matter, bulk density, and coarse-grained content. These proxies are used to correlate the two cores and assign timing to the one for which no absolute age data exists. Timing of glacial and interglacial events and marine isotope stages (MIS) is thus assigned. Rough estimates of sedimentation rates are compared, and large differences in rates are inferred. Differences in grain size between shallow and deep cores suggests that winnowing and transport of sediment from upslope is a factor in deposition in the area
LEONID ANDREYEV’S OEUVRE THROUGH BRUSOVIAN LENS
No full textThe paper deals with V. Brusov’s reviews of the works by Leonid Andreyev in the magazine «Vesy» (The Balance). The author mentions some peculiarities of L. Andreev’s stories positively reviewed by V. Brusov, as well as his remarks concerning the writer’s experiences in drama
Reflecting on Fiction: Leonid Leonov
No full textAbstract
This chapter examines the metafictional works of Soviet author Leonid Leonov. The River Sot, Leonov's third novel, was one of the earliest Soviet works in the theme of industrialization and it was based on the author's first-hand experience of Soviet construction projects. This novel, together with Leonov's other work The Thief, provided the direction that Soviet literature should take. These novels were both influenced by the October Revolution.</jats:p
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