1,272 research outputs found

    Sediment Mixing and Amorphous Weathering Products in a Glaciated Mars-Analog System

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    Modern climate models of Mars tend to predict a colder, icier early climate than previously imagined. While alteration of mafic terrain under warm, wet conditions is relatively well understood, a significant knowledge gap exists in how weathering might occur under redominantly glaciated environments on Mars. In such conditions, it is unclear whether all or any of the variety of aqueous alteration phases expressed in contemporaneous early martian surfaces could be formed, or how erosion of mafic bedrock and transport of sediment would comparatively change. Please see attachment

    Altimetry, gravimetry, GPS and viscoelastic modeling data for the joint inversion for glacial isostatic adjustment in Antarctica (ESA STSE Project REGINA)

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    The poorly known correction for the ongoing deformation of the solid Earth caused by glacial isostatic adjustment (GIA) is a major uncertainty in determining the mass balance of the Antarctic ice sheet from measurements of satellite gravimetry and to a lesser extent satellite altimetry. In the past decade, much progress has been made in consistently modeling ice sheet and solid Earth interactions; however, forward-modeling solutions of GIA in Antarctica remain uncertain due to the sparsity of constraints on the ice sheet evolution, as well as the Earth's rheological properties. An alternative approach towards estimating GIA is the joint inversion of multiple satellite data – namely, satellite gravimetry, satellite altimetry and GPS, which reflect, with different sensitivities, trends in recent glacial changes and GIA. Crucial to the success of this approach is the accuracy of the space-geodetic data sets. Here, we present reprocessed rates of surface-ice elevation change (Envisat/Ice, Cloud,and land Elevation Satellite, ICESat; 2003–2009), gravity field change (Gravity Recovery and Climate Experiment, GRACE; 2003–2009) and bedrock uplift (GPS; 1995–2013). The data analysis is complemented by the forward modeling of viscoelastic response functions to disc load forcing, allowing us to relate GIA-induced surface displacements with gravity changes for different rheological parameters of the solid Earth. The data and modeling results presented here are available in the PANGAEA database (https://doi.org/10.1594/PANGAEA.875745). The data sets are the input streams for the joint inversion estimate of present-day ice-mass change and GIA, focusing on Antarctica. However, the methods, code and data provided in this paper can be used to solve other problems, such as volume balances of the Antarctic ice sheet, or can be applied to other geographical regions in the case of the viscoelastic response functions. This paper presents the first of two contributions summarizing the work carried out within a European Space Agency funded study: Regional glacial isostatic adjustment and CryoSat elevation rate corrections in Antarctica (REGINA)

    Diversity of Tanaidacea (Crustacea: Peracarida) in the World's Oceans – How Far Have We Come?

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    Tanaidaceans are small peracarid crustaceans which occur in all marine habitats, over the full range of depths, and rarely into fresh waters. Yet they have no obligate dispersive phase in their life-cycle. Populations are thus inevitably isolated, and allopatric speciation and high regional diversity are inevitable; cosmopolitan distributions are considered to be unlikely or non-existent. Options for passive dispersion are discussed. Tanaidaceans appear to have first evolved in shallow waters, the region of greatest diversification of the Apseudomorpha and some tanaidomorph families, while in deeper waters the apseudomorphs have subsequently evolved two or three distinct phyletic lines. The Neotanaidomorpha has evolved separately and diversified globally in deep waters, and the Tanaidomorpha has undergone the greatest evolution, diversification and adaptation, to the point where some of the deep-water taxa are recolonizing shallow waters. Analysis of their geographic distribution shows some level of regional isolation, but suffers from inclusion of polyphyletic taxa and a general lack of data, particularly for deep waters. It is concluded that the diversity of the tanaidomorphs in deeper waters and in certain ocean regions remains to be discovered; that the smaller taxa are largely understudied; and that numerous cryptic species remain to be distinguished. Thus the number of species currently recognized is likely to be an order of magnitude too low, and globally the Tanaidacea potentially rival the Amphipoda and Isopoda in diversity

    Sediment Transport and Aqueous Alteration in a Mars-Analog Glacial System

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    The bulk of the Martian crust is basaltic with a wide variety of subsequently derived aqueous alteration phases. Study of analogue terrains is vital to better understand the weathering of such mafic bedrock at a range of surface temperatures. Moreover, climatic models have suggested that the early Martian climate was not warm and wet, but cold and icy, with some of the apparent fluvial and lacustrine features attributable to transient melting of ice sheets as opposed to persistent surface water. This study examines sediment samples from Collier glacial valley, Three Sisters, Oregon (OR), with the aim of better characterizing erosion, transport, and in situ aqueous alteration in a glaciated Mars-analogue terrain

    Basalt Weathering in a Cold and Icy Climate: Three Sisters, Oregon as an Analog for Early Mars

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    There is abundant evidence for liquid water on early Mars, but the debate remains whether early Mars was warm and wet or cold and icy with punctuated periods of melting. To further investigate the hypothesis of a cold and icy early Mars, we collected rocks and sediments from the Collier and Diller glacial valleys in the Three Sisters volcanic complex in Oregon. We analyzed rocks and sediments with X-ray diffraction (XRD), scanning and transmission electron microscopies with energy dispersive spectroscopy (SEM, TEM, EDS), and visible, short-wave infrared (VSWIR) and thermal-IR (TIR) spectroscopies to characterize chemical weathering and sediment transport through the valleys. Here, we focus on the composition and mineralogy of the weathering products and how they compare to those identified on the martian surface. Phyllosilicates (smectite), zeolites, and poorly crystalline phases were discovered in pro- and supra-glacial sediments, whereas Si-rich regelation films were found on hand samples and boulders in the proglacial valleys. Most phyllosilicates and zeolites are likely detrital, originating from hydrothermally altered units on North Sister. TEM-EDS analyses of the <2 um size fraction of glacial flour samples demonstrate a variety of poorly crystalline (i.e., no long-range crystallographic order) phases: iron oxides, devitrified volcanic glass, and Fe-Si-Al phases. The CheMin XRD on the Curiosity rover in Gale crater has identified significant amounts of X-ray amorphous materials in all samples measured to date. The amorphous component is likely a combination of silicates, iron oxides, and sulfates. Although we have not yet observed amorphous sulfate in the samples from Three Sisters, the variety of poorly crystalline weathering products found at this site is consistent with the variable composition of the X-ray amorphous component identified by CheMin. We suggest that these amorphous phases on Mars could have formed in a similarly cold and icy environment

    Семантические барьеры в деловой коммуникации

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    Статья из специализированного выпуска научного журнала "Культура народов Причерноморья", материалы которого объединены общей темой "Язык и Мир" и посвящены общим вопросам Языкознания и приурочены к 80-летию со дня рождения Николая Александровича Рудякова.Стаття із спеціалізованого випуску наукового журналу "Культура народов Причерноморья", матеріали якого поєднані загальною темою "Мова і Світ" і присвячені загальним питанням мовознавства і приурочені до 80-річчя з дня народження Миколи Олександровича Рудякова

    Особливості урбаністичного хронотопу в поезіях літугруповання “Бу-Ба-Бу”

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    Стаття присвячена дослідженню особливостей урбаністичного хронотопу в поезіях Ю. Андруховича, О. Ірванця, В. Неборака. Встановлено, що характерними модифікаціями урбаністичного хронотопу у творчості Ю. Андруховича є топографічний хронотоп із домінантами Львова й Станіслава та карнавалізоване Місто; у поезіях В. Неборака варіації урбаністичного хронотопу створюються за допомогою використання традиційних атрибутів міста, а також власне міських прошарків населення; урбаністичний хронотоп у поезіях О. Ірванця є найменше матеріалізованим і тяжіє до психологічно-метафізичного. Ключові слова: часопростір, хронотоп, топос, урбанізм, карнавалізація.Статья посвящена изучению особенностей урбанистического хронотопа в поэзиях Ю. Андруховича, А. Ирванца, В. Неборака. Так, в творчестве Ю. Андруховича были выявлены такие модификации урбанистического хронотопа, как топографический с доминантами Львова и Станислава и карнавальный Город; в поэзиях В. Неборака вариации урбанистического хронотопа осуществляются при помощи использования традиционных атрибутов города, а также собственно городских слоев населения; урбанистический хронотоп поэзий А. Ирванца наименее материализован и тяготеет к психологически-метафизическому. Ключевые слова: пространственно-временное единство, хронотоп, топос, урбанистичность, карнавальность.The article is dedicated to the study of the urbanism chronotope’s particularities in Yu. Andruhovicha, A. Irvanca, V. Neboraka poetry. So in Yu. Andruhovich’s work. Such modification urbanism chronotope as topographical one with the Livov and Stanislav’s dominant and the carnival one. In V. Neboraka’s variations of urbanism chronotope are realized using the traditional city attributes and town population layers as well. A. Irvanc’s poetry urbanism chronotope is less materialired and strongly attracted by psychological-metaphysical one. Keywords: space-time unity, chronotope, urbanism, carnivalization

    Ice sheet contributions to future sea-level rise from structured expert judgment

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    Despite considerable advances in process understanding, numerical modeling, and the observational record of ice sheet contributions to global mean sea-level rise (SLR) since the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change, severe limitations remain in the predictive capability of ice sheet models. As a consequence, the potential contributions of ice sheets remain the largest source of uncertainty in projecting future SLR. Here, we report the findings of a structured expert judgement study, using unique techniques for modeling correlations between inter- and intra-ice sheet processes and their tail dependences. We find that since the AR5, expert uncertainty has grown, in particular because of uncertain ice dynamic effects. For a +2 °C temperature scenario consistent with the Paris Agreement, we obtain a median estimate of a 26 cm SLR contribution by 2100, with a 95th percentile value of 81 cm. For a +5 °C temperature scenario more consistent with unchecked emissions growth, the corresponding values are 51 and 178 cm, respectively. Inclusion of thermal expansion and glacier contributions results in a global total SLR estimate that exceeds 2 m at the 95th percentile. Our findings support the use of scenarios of 21st century global total SLR exceeding 2 m for planning purposes. Beyond 2100, uncertainty and projected SLR increase rapidly. The 95th percentile ice sheet contribution by 2200, for the +5 °C scenario, is 7.5 m as a result of instabilities coming into play in both West and East Antarctica. Introducing process correlations and tail dependences increases estimates by roughly 15%.</p
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