O continente Antártico é considerado um ambiente pouco impactado, porém com o aumento das atividades humanas e do número de estações de pesquisa, há uma tendência de aumento dos níveis de alguns contaminantes. Neste estudo estabeleceram-se os níveis de arsênio, cádmio, chumbo, cobre, cromo, mercúrio, níquel, zinco, e a razão isotópica de nitrogênio, em sedimentos e na biota, coletados em 2003, na Baía do Almirantado, Ilha Rei George, Antártica. Os metais pesados foram quantificados por Espectrometria de Emissão Ótica com Plasma Indutivamente Acoplado (ICP-OES). Os resultados demonstraram elevadas concentrações de cobre e zinco nos sedimentos, atribuídas à composição geológica da região. Verificou-se bioacumulação de arsênio na biota da Baía do Almirantado, e bioacumulação de cádmio e zinco na biota da Enseada Martel. Somente cobre apresentou tendência de biomagnificação na teia trófica estudada. O molusco Laternula elliptica se apresentou como um bom biomonitor das concentrações de metais pesados para o ambiente Antártico. Além disso, os resultados foram úteis para o conhecimento dos níveis de metais pesados nas condições pré-acidente da Estação Antártica Comandante Ferraz (EACF), que ocorreu em 2012, e para comparação com as atuais condições, dentro dos trabalhos de monitoramento que estão sendo realizados pelo INCT-APA (Instituto Nacional de Ciência e Tecnologia Antártico de Pesquisas Ambientais). / The Antarctic continent is considered a slightly affected environment, but as the human activities and the number of research stations are increasing, there is a tendency of a higher level of some contaminants. This study established the levels of arsenic, cadmium, lead, copper, chromium, mercury, nickel, zinc, and nitrogen isotope ratios in sediments and biota collected in 2003, in Almirantado Bay, Rei George Island, Antarctica. Heavy metals were quantified by Optical Emission Spectrometry with Inductively Coupled Plasma (ICP-OES). The results showed high concentrations of copper and zinc in sediments attributed to the geological composition of the region. There was arsenic bioaccumulation in biota of Almirantado Bay, and bioaccumulation of cadmium and zinc in the biota of Martel Bay. Only copper tended to biomagnification in the trophic web studied. The clam Laternula elliptica presented itself as a good biomonitor of heavy concentrations of metals for Antarctic environment. Moreover, the results were useful for the acknowledge of the levels of heavy metals in pre-accident conditions of Comandante Ferraz Antarctic Station (EACF), which occurred in 2012, and for comparison with current conditions within the monitoring work now performed by INCT-APA (National Antartic Institute of Science and Technology Environmental Research).

Os depósitos cenozoicos da Antártica Ocidental, especialmente aqueles da transição Eoceno-Oligoceno, fornecem importantes dados geológicos sobre as mudanças climáticas ocorridas ao longo da Era Cenozoica e de seu impacto na biosfera austral. Assembleias fósseis, incluindo de foraminíferos, foram relatadas para unidades de todas as épocas cenozoicas, em afloramentos dos arquipélagos James Ross e Shetlands do Sul. Todavia, os diamictitos das Formações Hobbs Glacier (Mioceno) e Weddell Sea (Plio-Pleistoceno), que afloram nas ilhas James Ross e Seymour, ainda não haviam sido alvo de análises micropaleontólogicas visando a obtenção de microfósseis com paredes inorgânicas. Foram analisadas amostras de 12 seções estratigráficas da Ilha Seymour, incluindo estratos do topo da Formação La Meseta (Eoceno) e de diversos níveis das formações Hobbs Glacier e Weddell Sea. Pela primeira vez foram encontradas assembleias de microfósseis com paredes inorgânicas, constituídas principalmente por foraminíferos, na porção superior da Formação La Meseta e em estratos das formações Hobbs Glacier e Weddell Sea. Na Formação La Meseta foram encontrados restos autóctones ou parautóctones de foraminíferos Textularia sp., primeira ocorrência do gênero para a unidade. Na Formação Hobbs Glacier, a assembleia autóctone ou parautóctone melhor preservada é composta pelo foraminífero lagenído Oolina stellula e pelo radiolário Larcopyle polyacantha. O foraminífero rotaliído Bolivina sp. é raro e representa um resto alóctone na unidade. Para a Formação Weddell Sea, a assembleia autóctone ou parautóctone melhor preservada é constituída pelo foraminífero lagenído Favulina hexagona e pelo planctônico Globigerinita uvula, além do rotaliído Globocassidulina subglobosa e do radiolário L. polyacantha nos mesmos e em outros níveis. Nos depósitos miocênicos e plio-pleistocênicos ocorrem também foraminíferos aglutinados grandes de táxons típicos de mar profundo, cujas feições tafonômicas indicam sua reelaboração a partir de depósitos mais antigos, possivelmente do Paleoceno, tendo em vista sua associação tafonômica e estratigráfica com o foraminífero Reticulophragmium garcilassoi, um fóssil-índice dessa época. Além de R. garcilassoi, ocorrem outros táxons típicos de assembleias de mar profundo na Formação Hobbs Glacier, como Alveolophragmium orbiculatum, Ammodiscus sp. nov., Ammodiscus pennyi, Ammomarginulina cf. aubertae, Bathysiphon sp. 1, Bathysiphon sp. 2, Cyclammina placenta e Nothia robusta. Na Formação Weddell Sea, as grandes formas aglutinadas são representadas por Ammodiscus sp. nov., Bathysiphon sp. 1, Budashevaella cf. laevigata, Cyclammina cancellata, Glomospira charoides, Saccammina grzybowski, Sculptobaculites barri e Verneulinoides cf. neocomiensis. Alguns táxons da Ilha Seymour podem ser associados àqueles dos depósitos paleocênicos da Nova Zelândia e Nova Guiné, sugerindo alguma correlação cronológica. Embora o registro fossilífero das formações La Meseta, Hobbs Glacier e Weddell Sea seja rarefeito, foi possível identificar restos autóctones ou parautóctones que indicaram a composição parcial das comunidades infaunais e planctônicas que habitavam a região durante a deposição das unidades. Os poucos fósseis-índice encontrados corroboram as idades já propostas paras as formações. Para a Formação Weddell Sea, as assembleias autóctones ou parautóctones e as formas planctônicas permitiram redefinir o contexto deposicional da unidade como glacio-marino, e não plenamente glacial, como anteriormente proposto. / Western Antarctic deposits, especially those from the Eocene-Oligocene transition, provide important geological data on Cenozoic global climate changes and their impact on the southern biota. Fossil assemblages, including foraminifers, are known from geological units from all Cenozoic epochs, in outcrops of the James Ross and South Shetlands archipelagos. However, the diamictites of Hobbs Glacier (Miocene) and Weddell Sea (Plio-Pleistocene) formations, exposed in James Ross and Seymour islands, were never subjects of micropaleontologic analysis targeting inorganic-walled microfossils. Twelve stratigraphic sections on Seymour Island were analyzed, including the top of the La Meseta Formation (Eocene) and several strata of Hobbs Glacier and Weddell Sea formations. Assemblages of inorganic-walled microfossils, composed mainly of foraminifers, were found for the first time in the La Meseta Formation and in strata from the Hobbs Glacier and Weddell Sea formations. Autochthonous or parautochthonous remains of the foraminifer Textularia sp. were found in the La Meseta Formation, being the first occurrence of the genus in this unit. The best preserved autochthonous or parautochthonous assemblage from Hobbs Glacier Formation is composed of the Lagenid foraminifer Oolina stellula and radiolarian Larcopyle polyacantha. The Rotaliid foraminifer Bolivina sp. is rare and represents an allochthonous elements in this formation. In the Weddell Sea Formation, the best preserved autochthonous or parautochthonous assemblage is composed of the Lagenid foraminifer Favulina hexagona and the planktonic Globigerinita uvula, as well as the Rotaliid foraminifer Globocassidulina subglobosa and the radiolarian L. polyacantha in the same and in other strata. In these Miocene and Plio-Pleistocene deposits also occur large agglutinated foraminifers typical of the deep sea, whose taphonomic features indicate their reelaboration from older deposits, possibly from the Paleocene, given their taphonomic and stratigraphic association with the foraminifer Reticulophragmium garcilassoi, a Paleocene index-fossil. Besides R. garcilassoi, other typical deep-sea taxa occur in the Hobbs Glacier Formation, such as Alveolophragmium orbiculatum, Ammodiscus sp. nov., Ammodiscus pennyi, Ammomarginulina cf. aubertae, Bathysiphon sp. 1, Bathysiphon sp. 2, Cyclammina placenta and Nothia robusta. In the Weddell Sea Formation the agglutinated specimens are represented by Ammodiscus sp. nov., Bathysiphon sp. 1, Budashevaella cf. laevigata, Cyclammina cancellata, Glomospira charoides, Saccammina grzybowski, Sculptobaculites barri and Verneulinoides cf. neocomiensis. Some taxa from Seymour Island also occur in the Paleocene deposits of New Zealand and New Guinea, suggesting some chronological correlation. Although the fossil record of the La Meseta, Hobbs Glacier and Weddell Sea formations is sparse, it was possible to identify autochthonous or parautochthonous remains that indicate the partial composition of the infaunal communities and plankton that thrived in the area during the deposition of the units. The few index-fossils found corroborate the ages already indicated for the deposits. For the Weddell Sea Formation, the autochthonous or parautochthonous assemblages and the planktonic specimens allowed the redefinition of its depositional setting as glacial-marine, and not fully glacial, as previously proposed.

Memoria para optar al Título Profesional de Ingeniero Forestal / Durante la colonización del territorio chileno, alrededor de tres millones de hectáreas de bosque nativo norpatagónico fueron incendiadas por el hombre, para la habilitación de terrenos para la agricultura y la ganadería. Las experiencias de reforestación con especies arbóreas nativas en la zona son escasas. El objetivo de este trabajo fue evaluar el crecimiento y el daño por herbivoría durante los dos primeros años de establecida una plantación con Nothofagus antarctica y Nothofagus betuloides. El estudio se realizó en una plantación de 56 ha ubicada en el Valle California (43º44’ LS, 71º48’LO), Provincia de Palena, Chile, realizada durante el año 2010 por la Sociedad Agrícola y Forestal SNP Patagonia Sur. En el año 2011 se establecieron 10 de parcelas de 400 m2 (20 x 20 m), para monitoreo permanente. En los veranos de los años 2011 y 2012 se midió la longitud y el diámetro a la altura del cuello (DAC) de todas las plantas vivas, y se determinó además el agente de daño (liebre o ratón). El nivel de daño por herbivoría se evaluó a través de una adaptación del Browse Rating Index (BRI) que adquiere valores desde 0 a 4, según el nivel de daño visualizado, con 0 = sin daño, 1 = daño leve (<20% de la planta afectada); 2 = daño moderado (20-45%); 3 = daño grave (>45%) y 4 = muerto. La densidad de plantación inicial fue de 1.300 plantas/ha. La supervivencia al segundo año de monitoreo de N. antarctica y N. betuloides fue del 95,3% y 37,7% de las plantas, respectivamente. El incremento corriente anual (ICA) en longitud fue de 12,8 cm y 7,4 cm, para cada una de las especies, respectivamente. El ICA en DAC fue de 1,86 mm y 1,68 mm, respectivamente.

Experience of Antarctica is unique and overwhelming and the phenomenon of the landscape and knowledge of its history continues to inspire artists and writers. Since Antarctica's discovery and exploration both before and during the Heroic Age; explorers, expeditioners, artists and writers have attempted to record and visualise Antarctica. In1982 international Antarctic programmes started to assist artists to travel to Antarctica with the intention of providing perceptive interpretations no longer attached to science or exploration. This practice-led research is the first project where a jeweller has explored and interpreted a personal experience of Antarctica to produce souvenir and jewellery objects. These objects reveal new interpretations of Antarctica that engage with the viewer through the recognisable personal jewellery and souvenir object. This research has produced new contemporary souvenir and jewellery objects by interpreting both personal photographs and re-examining the historic stories, photographs and representations of Antarctica. The bibliographic investigations of historical jewellery and souvenirs provided specific examples of historical personal mementos that are now displayed in museums. This research analyses the meaning of historical examples of souvenirs and jewellery and examines the way in which photography has been manipulated and used on hard media. Through this analysis and examination of historical examples the research focuses on studio-based experimentation with enamelling and contemporary technologies to establish the links enamelling has had with micromosaics and miniature painting. This practice-led research investigates new and innovative ways to interpret these historical techniques and draw on the notion of the souvenir. Thinking through the processes used in this research and retelling the personal experience of Antarctica, contemporary technologies are used to reimagine historical examples of tourist jewellery and personal souvenirs presenting a further understanding of Antarctica's significance both culturally and environmentally. The research not only provides an addition to the diverse range of interpretations of Antarctica it also explores the area of enamelling in contemporary jewellery and object making by contributing to the current revival of the tradition both locally and internationally. This research offers new experiences and knowledge through the investigation, experimentation, manufacture and installation of enamelled objects.

Mt. Morning is a 2,732 m high, Cenozoic, alkaline eruptive centre situated in the south-west corner of McMurdo Sound in the Ross Sea, Antarctica. Mt. Morning is approximately 100 km south-west of Mt. Erebus, the world's southernmost active volcano. Several Cenozoic, alkali eruptive centres in this region make up the Erebus Volcanic Province. The region is currently undergoing continental extension. Regional-scale, north-striking faulting on the northern flank of Mt. Morning has offset vertical dykes, as young as 3.9 Ma, by up to 6 m dextrally. This is consistent with the trans-extensional regime in the region. The faults also have a dip-slip component, downthrown to the east. These faults define part of the western boundary of the West Antarctic Rift System. Mt. Morning straddles the boundary between the continental rift shoulder of the Transantarctic Mountains in Southern Victoria Land, and the perceived oceanic crust of the Ross Sea. Age determination of the youngest offset dyke constrains movement in the last 3.88 � 0.05 m.y., to an average rate of 0.0015 mm per year. Volcanism on Mt. Morning is divided into two phases. Phase I was erupted between 18.7 � 0.3 and 114 � 0.2 Ma and Phase II between 6.13 � 0.20 and 0.15 � 0.01 Ma. The two phases are separated by a 5.3 m.y. period of quiescence. The geochemistry of Phase I is mildly alkaline; it is composed of volcaniclastic deposits, dykes, sills, and volcanic plugs of nepheline-basanite, nepheline-trachyte, quartz-mugearite, quartz-trachyte, and rhyolite. Phase I rocks evolved along at least two trends: a quartz normative trend, and a nepheline normative trend. Chemical variation in Phase I can be explained in part by crystal fractionation, which has been modelled using major element multiple linear regression. Phase I quartz-mugearite can fractionate to quartz-trachyte after 44% crystallisation. Quartz-trachyte can fractionate to rhyolite after a further 6% erystallisation. The models indicate that clinopyroxene + plagioclase + opaque oxides � alkali feldspar � apatite are the dominant fractionated phases. Many of the Phase I quartz normative volcanic rocks have relatively high ⁸⁷Sr/⁸⁶Sr ratios (0.70501), suggesting that assimilation, most likely of crustal material, has modified them. Phase I nepheline-basanite can fractionate to nepheline-trachyte after 68% crystallisation. Modelling indicates clinopyroxene + nepheline + olivine + opaque oxides are the dominant fractionated phases. Phase II volcanic rocks are strongly alkaline and are mapped as flows, volcaniclastic deposits, dykes, and sills. They have been erupted mainly from parasitic scoria vents and rarely from fissure vents. Rock types include picrobasalt, basalt, basanite, tephrite, hawaiite, mugearite, phonotephrite, tephriphonolite, benmoreite, and phonolite. Chemical variations in the Phase II volcanic rocks can be explained by simple fractionation. Phase II picrobasalt can fractionate to phonotephrite after 78% crystallisation. Phonotephrite can fractionate to phonolite after at least 35% crystallisation, depending on which of several multiple linear regression models are selected. Fractionation is dominated by the removal of clinopyroxene + plagioclase + nepheline + olivine + opaque oxides � apatite � kaersutite. Volcanic rocks in the Erebus Volcanic Province are strongly alkaline on a silica versus total alkalis plot, similar to the Phase II volcanic rocks from Mt. Morning. Mildly alkaline rocks of Phase I are, to date, unique within the Erebus Volcanic Province. Bulk rock isotope ratios of ⁸⁶Sr/⁸⁷Sr (0.70307 - 0.70371 and 0.70498 - 0.70501), �⁴�Nd/�⁴⁴Nd (0.512650 - 0.512902), and �⁰⁶Pb/�⁰⁴Pb (18.593 -20.039) show that the majority of Mt. Morning volcanic rocks lie on a mixing line between HIMU (high-[mu]; enriched in �⁰⁶Pb and �⁰⁸Pb and relatively depleted in ⁸⁶Sr/⁸⁷Sr values) and DM (depleted mantle; high �⁴�Nd/�⁴⁴Nd, low ⁸⁶Sr/⁸⁷Sr, and low �⁰⁶Pb/�⁰⁴Pb). This is similar to the majority of volcanic rocks from the SW Pacific, including Antarctica and New Zealand. Mt. Morning volcanic rocks have tapped this broadly common mantle reservoir. There are variations in radiogenic isotope ratios between Mt. Morning and Mt. Erebus. There are also differences between the incompatible element ratios in volcanic rocks from Mt. Morning, Mt. Erebus, and White Island (a third eruptive centre in the Erebus Volcanic Province), suggesting heterogeneity in the mantle beneath the Erebus Volcanic Province. Significant chemical differences are also noted between ultramafic xenoliths collected from Mt. Morning and from Foster Crater only 15 km away. This suggests a deca-kilometre, possibly even kilometre-scale, heterogeneity in the mantle. Such small-scale chemical differences appear difficult to reconcile with large-scale plume hypotheses for the initiation of volcanism in the Erebus Volcanic Province. Instead, volcanism is much more likely to be related to numerous small plumes, or the preferred hypothesis, metasomatism and amagmatic rifting, followed by decompression melting of upwelling mantle and volcanism during transtensional lithospheric rifting. This latter model is supported by a lack of regional updoming expected with a plume(s), and fits models of localised extension proposed in this thesis. Calc-alkaline and alkaline igneous xenoliths, of felsic to mafic crustal material, have been collected from Mt. Morning. U-Pb geochronology (545.4 � 3.7 Ma and 518.6 � 4.4 Ma) on crustal xenoliths from Mt. Morning illustrate that the basement is Cambrian. Bulk rock chemistry of crustal xenoliths has similarities to compositions reported for Ross Orogen rocks, suggesting the Mt. Morning volcanic edifice is built on a basement that is composed of Cambrian Ross Orogen rock types. Quartz-bearing felsic granulite xenoliths with greater than 70 weight percent silica, collected from Mt. Morning, suggest that part of the basement is felsic. This is the only occurrence of felsic xenoliths reported to date east of the present day coastline of Victoria Land. Mt. Morning crops out less than 25 km from the known northern end of the Koettlitz Glacier Alkaline Province in the Transantarctic Mountains. The partially alkaline basement beneath Mt. Morning suggests the province may continue beneath part of Mt. Morning. The mantle beneath Mt. Morning can be characterised as anhydrous and otherwise largely unmetasomatised, which is atypical of xenoliths collected from the western Ross Sea. Only a handful of Mt. Morning xenoliths show petrographic evidence of metasomatism, these include modal phlogopite, apatite, Fe-Ni sulphide, and plagioclase (in pyroxenite xenoliths), suggesting metasomatising fluids occur discretely in this region. Where present, the metasomatic fluid(s) beneath Mt. Morning are enriched in Ba, LREEs, Th, U, P, Fe, Ni, S, and K, and depleted in Ti relative to the metasomatic fluid composition described at nearby Foster Crater. Oxygen fugacity (fO₂) of the Antarctic shallow mantle has been measured from xenoliths collected from Mt. Morning, where fO₂ was demonstrated to be strongly dependant upon spinel Fe�⁺ content that was measured using Mössbauer spectroscopy, and calculated from the olivine-orthopyroxene-spinel oxybarometer. fO₂ in the rifted Antarctic mantle varies between 0.1 and -1 log units relative to the fayalite-magnetite-quartz buffer and is coupled to melt depletion, with increasing degrees of melt extraction resulting in a more oxidised mantle. This range of upper mantle fO₂ is commonly observed in continental rift settings worldwide. The mantle beneath Mt. Morning is composed of, in increasing degree of fertility, dunite, harzburgite, and lherzolite. Xenoliths representing discrete samples of this mantle have mostly crystallised in the spinel stability field of the mantle at pressures of approximately 15 kb and temperatures between 950 - 970 �C. Symplectites of spinel and pyroxene have been interpreted as petrographic evidence that some of the spinel peridotite originated in the garnet stability field of the mantle. Rare plagioclase-bearing spinel lherzolite (plagioclase lherzolite) is also present in the mantle beneath Mt. Morning, which crystallised at temperatures of between 885 and 935 �C at 5 kb. The Mt. Morning peridotite xenoliths plot along the pre-defined geotherm for the Erebus Volcanic Province, strongly supporting it as the appropriate choice of geothermal gradient for south-west McMurdo Sound. Mineral and bulk rock compositions are nearly identical between the plagioclase lherzolite xenoliths and spinel lherzolite xenoliths. Mineral and bulk rock chemistry suggest it is unlikely that the plagioclase is due to metasomatism. Petrographic evidence and mass balance calculations suggest that the plagioclase lherzolite has crystallised via a sub-solidus (metamorphic) transition from spinel lherzolite upon decompression and upwelling of the mantle. The occurrence of plagioclase lherzolite beneath Mt. Morning could be explained by lithospheric scale uplift along faults that define the western margin of the West Antarctic Rift System. Plagioclase lherzolite has also been collected and described from White Island. White Island is also interpreted to straddle lithospheric scale faults. Rifting and buoyant uplift is sufficient to explain the presence of plagioclase lherzolite in the Erebus Volcanic Province. Plagioclase lherzolite has also been described from Mt Melbourne, an eruptive centre in Northern Victoria Land. Known occurrences of plagioclase lherzolite from the western shoulder of the Ross Sea now cover an area 430 km long and 80 km wide. This is one of the largest provinces of plagioclase peridotite worldwide so far reported.

Antarctica is one of the most beautiful and remote places on the planet. The moniker of being the highest, driest, coldest, iciest, windiest, most remote continent, surrounded by the stormiest ocean is well deserved, yet it also acts as quite a draw for visitors. Despite the fact that visitor numbers have been steadily rising for the past 15 years, very little is empirically known about the experience these visitors have, particularly outside of the Antarctic Peninsula region. This lack of understanding is particularly detrimental from the perspective of visitor management, as is being discovered by agencies worldwide. As such, the aim of this thesis is to report on a study of visitor experiences in the Ross Sea region of Antarctica. Visitors are defined as those who come into physical contact with the continent, and whose primary activity and purpose is simply "being there." Visitors are a wider population than just commercial tourists aboard cruise ships; visitors are not passengers on commercial overflights, the scientists or base and support staff. Experience is defined as a longitudinal period—looking at visitors well in advance of their visit, throughout their time on site, and following up back at their homes. The Ross Sea region is essentially equivalent to New Zealand's Ross Dependency, a section of the Antarctic "pie" from the South Pole to 60°S, bounded by approximately 150°E and 150°W. Using a three-phase methodology to examine the cycle of experience, the purpose of this study is to compare groups of visitors with four organisations through this cycle, and analyse for change or transition as a result of their visit. The visitors were participants, to varying degrees, in a number of data-gathering methods during the 2002–2003 or 2003–2004 seasons. Such methods included: self-administered surveys sent to the respondents' home (up to three months in advance of the trip); personal narratives and journals while on the trip (regardless of trip length; 4–28 days); in-depth interviews held in Christchurch directly before and after the trip when possible; and email surveys (two to three months following the visit). In 2003–2004, a supplemental season of data was collected that included a researcher familiarisation visit, participant observation, and informal interviews at Scott Base. These supplemental data helped shape the researcher's own thoughts and thus comments in the Discussion sections. Results indicate both similarities and differences as compared to previous research; key findings include: scenery was a strong motivator and component of image; expectations were for a safe and professional learning; mood was positive throughout all phases; visitation was both acceptable and problematic; the environment was important, even in advance of the visit; education was an essential benefit of the visit; the Ross Sea region was an impressive and awe-inspiring locale; organisational differences were apparent when discussing people and the role of transportation to the continent; historic huts were uniformly amazing sites for the feelings they instil; expectations were virtually always exceeded; awareness changed over the experience; sharing of awareness and teaching from one's learning had occurred; action may or may not have occurred on various specific issues, but the label of ambassador was respondent-perceived to be acceptable. This study concludes with a number of implications for theory, methods, and logistics, which will hopefully lead to future research that is much wider in scope (geographically), but equally inclusive in terms of methods and ability to utilize and critique theories built outside of purely tourism research.

<p>Climate and environmental change following the retreat of the last glacial ice sheet in the Antarctic Peninsula has been interpreted, employing diatom abundance, relative abundance of <i>Chaetoceros</i> resting spores and diatom assemblages as proxies. These together with sedimentological data and radiocarbon dating, suggest four major events that can be further subdivided.</p><p>Deglaciation ~13.2-11.5 kyr BP with ice shelf breakup and strong surface water stratification from melting ice. </p><p>Climate reversal ~11.5-9.0 kyr BP with turbulent water masses. </p><p>Climate optimum ~9.0-4.0 kyr BP with intrusions of northern ´warm` water masses. </p><p>Neoglacial ~4.0 kyr BP-present with extended periods of sea ice cover and increased storm frequency. </p><p>One aspect of climate change is the stability of marine based ice sheets, and the interaction with underlying sediment. A pilot study on characterizing sediment influenced by past ice streaming (Ross Sea) was performed using diatom, texture and chemical analysis. The results show that:</p><p>Diamictons are chemically and texturally well homogenized, whereas diatom assemblages suggest different degrees of stratigraphic mixing and reworking related to mode of glacial sediment transport. </p><p>Mud appears in different stratigraphic sections deposited in sub-ice shelf or ice edge environment, or through winnowing by currents. This is evident through stratigraphically-diverse diatom assemblages and texture. Most sediment characterized as mud is enriched in zinc (Zn). </p><p>Hemipelagic diatomaceous muds are enriched in barium (Ba) and the diatom assemblage is dominated by typical neritic post-glacial species.</p>

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 132-144).

The Antarctic plays an important role in the global climate system. On the one hand, the Antarctic Ice Sheet is the largest freshwater reservoir on Earth. On the other hand, a major proportion of the global bottom-water formation takes place in Antarctic shelf regions, forcing the global thermohaline circulation. The main goal of this dissertation is to provide new insights into the dynamics and stability of the EAIS during the Quaternary. Additionally, variations in the activity of bottom-water formation and their causes are investigated. The dissertation is a German contribution to the International Polar Year 2007/ 2008 and was funded by the ‘Deutsche Forschungsgesellschaft’ (DFG) within the scope of priority program 1158 ‘Antarctic research with comparative studies in Arctic ice regions’. During RV Polarstern expedition ANT-XXIII/9, glaciomarine sediments were recovered from the Prydz Bay-Kerguelen region. Prydz Bay is a key region for the study of East EAIS dynamics, as 16% of the EAIS are drained through the Lambert Glacier into the bay. Thereby, the glacier transports sediment into Prydz Bay which is then further distributed by calving icebergs or by current transport. The scientific approach of this dissertation is the reconstruction of past glaciomarine environments to infer on the response of the Lambert Glacier-Amery Ice Shelf system to climate shifts during the Quaternary. To characterize the depositional setting, sedimentological methods are used and statistical analyses are applied. Mineralogical and (bio)geochemical methods provide a means to reconstruct sediment provenances and to provide evidence on changes in the primary production in the surface water column. Age-depth models were constructed based on palaeomagnetic and palaeointensity measurements, diatom stratigraphy and radiocarbon dating. Sea-bed surface sediments in the investigation area show distinct variations in terms of their clay minerals and heavy-mineral assemblages. Considerable differences in the mineralogical composition of surface sediments are determined on the continental shelf. Clay minerals as well as heavy minerals provide useful parameters to differentiate between sediments which originated from erosion of crystalline rocks and sediments originating from Permo-Triassic deposits. Consequently, mineralogical parameters can be used to reconstruct the provenance of current-transported and ice-rafted material. The investigated sediment cores cover the time intervals of the last 1.4 Ma (continental slope) and the last 12.8 cal. ka BP (MacRobertson shelf). The sediment deposits were mainly influenced by glacial and oceanographic processes and further by biological activity (continental shelf), meltwater input and possibly gravitational transport. Sediments from the continental slope document two major deglacial events: the first deglaciation is associated with the mid-Pleistocene warming recognized around the Antarctic. In Prydz Bay, the Lambert Glacier-Amery Ice Shelf retreated far to the south and high biogenic productivity commenced or biogenic remains were better preserved due to increased sedimentation rates. Thereafter, stable glacial conditions continued until 400 - 500 ka BP. Calving of icebergs was restricted to the western part of the Lambert Glacier. The deeper bathymetry in this area allows for floating ice shelf even during times of decreased sea-level. Between 400 - 500 ka BP and the last interglacial (marine isotope stage 5) the glacier was more dynamic. During or shortly after the last interglacial the LAIS retreated again due to sea-level rise of 6 - 9 m. Both deglacial events correlate with a reduction in the thickness of ice masses in the Prince Charles Mountains. It indicates that a disintegration of the Amery Ice Shelf possibly led to increased drainage of ice masses from the Prydz Bay hinterland. A new end-member modelling algorithm was successfully applied on sediments from the MacRobertson shelf used to unmix the sand grain size fractions sorted by current activity and ice transport, respectively. Ice retreat on MacRobertson Shelf commenced 12.8 cal. ka BP and ended around 5.5 cal. ka BP. During the Holocene, strong fluctuations of the bottomwater activity were observed, probably related to variations of sea-ice formation in the Cape Darnley polynya. Increased activity of bottom-water flow was reconstructed at transitions from warm to cool conditions, whereas bottom-water activity receded during the mid- Holocene climate optimum. It can be concluded that the Lambert Glacier-Amery Ice Shelf system was relatively stable in terms of climate variations during the Quaternary. In contrast, bottom-water formation due to polynya activity was very sensitive to changes in atmospheric forcing and should gain more attention in future research. / Die Antarktis spielt im globalen Umweltsystem eine tragende Rolle. Mit ihrem mächtigen Eispanzer ist sie nicht nur der größte Süsswasserspeicher auf der Erde, in ihren Schelfregionen wird auch ein Großteil der globalen Bodenwassermassen gebildet, welche die globale thermohaline Zirkulation antreiben. Hauptziel dieser Arbeit, welche einen deutschen Beitrag zum Internationalen Polarjahr 2007/ 2008 liefert, war es, neue Erkenntnisse hinsichtlich der Stabilität des Ostantarktischen Eisschildes während des Quartärs zu liefern. Weiterhin sollten Aussagen über Variationen in der Bildung von Antarktischem Bodenwasser und deren Ursachen getroffen werden. Dazu wurde im Rahmen der ‚Polarstern‘ Expedition ANT-XXIII/9 eine Beprobung glaziomariner Sedimente zwischen Prydz Bucht und Kerguelen Plateau durchgeführt. Diese Region eignet sich zur Untersuchung der Ostantarktischen Eisdynamik besonders gut, da hier der Lambert Gletscher, etwa 16% des Ostantarktischen Eispanzers drainiert. Er transportiert dabei Sediment nach Norden, das schließlich die Prydz Bucht erreicht und durch direkten Transport über kalbende Eisberge oder durch Umlagerung und Verteilung mithilfe von Meeresströmungen weiter verfrachtet wird. Der wissenschaftliche Ansatz dieser Arbeit besteht darin, über die Verteilung dieser Sedimente in Raum und Zeit, d.h. über Variationen des glaziomarinen Paläoregimes, die Reaktion des Lambert Gletschers und des vorgelagerten Amery Schelfeises auf Klimaschwankungen während des Quartärs zu rekonstruieren. Dabei werden sowohl sedimentologische Methoden unter Einbeziehung neuer statistischer Möglichkeiten angewandt, um Sedimentationsprozesse zu charakterisieren, als auch mineralogische und (bio)geochemische Parameter verwendet, um Aussagen über die Herkunft der Sedimente und Änderungen in der Produktivität im Oberflächenwasser treffen zu können. Die Altersbestimmung der Sedimentkerne erfolgte mittels Paläomagnetik, Paläointensitäten, Biostratigraphie und Radiokarbondatierungen. Die Oberflächensedimente im Untersuchungsgebiet zeigen deutliche Unterschiede sowohl hinsichtlich ihrer Tonmineral- als auch Schwermineralzusammensetzung. Beide mineralogischen Parameter zeigen die größten Differerenzen auf dem Schelf. Dort lassen sich deutlich Sedimente der Prydz Bucht von Sedimenten des MacRobertson Shelfes differenzieren. Sie stellen daher ein gutes Hilfsmittel dar, um sowohl die Herkunft von eis- als auch strömungstransportiertem Material zu rekonstruieren. Die untersuchten Sedimentkerne decken den Zeitraum der letzten 1,4 Millionen Jahre (Kontinentalhang) bzw. der letzten 12,8 tausend kal. Jahre v. H. ab (MacRobertson Schelf). Die abgelagerten Sedimente wurden i. W. durch glaziale und ozeanographische Einflüsse geprägt, aber auch durch Bioproduktion (Schelf) bzw. durch Schmelzwassereinträge und möglicherweise gravitative Prozesse (Kontinentalhang). In den Sedimenten des Kontinentalhangs sind zwei starke Enteisungsereignisse überliefert: Das erste Ereignis steht mit dem mittelpleistozänen Klimaoptimum in Verbindung, das auch in anderen antarktischen Regionen nachgewiesen wurde. Es führte in der Prydz Bucht zu einem weitreichenden Rückzug des Lambert Gletscher-Amery Schelfeises (LAIS) und gleichzeitig zu einer hohen Primärproduktion. Danach herrschten bis etwa 400 - 500 tausend Jahre v. H. stabile glaziale Bedingungen. Kalbung von Eisbergen war wahrscheinlich auf den westlichen Teil des Lambert Gletschers begrenzt, wo eine tiefere Bathymetrie auch bei niedrigerem globalen Meeresspiegel noch Aufschwimmen des Gletschereises erlaubt. Zwischen 400 - 500 tausend Jahren v. H. und vermutlich dem letzten Interglazial wurde der Gletscher schließlich wieder dynamischer, um mit oder kurz nach dem letzten Interglazial (Meeresspiegel etwa 6 - 9 m höher) eine weitere Phase deutlichen Rückzuges zu durchlaufen. Beide Ereignisse lassen sich mit Phasen der Eisreduktion in den Prinz Charles Bergen korrelieren, d.h. der Rückzug des Lambert Gletschers hatte möglicherweise ein erhöhtes Nachfließen von Eismassen aus dem Hinterland zur Folge. An den Sedimenten des Schelfkernes wurde ein neu entwickeltes Verfahren der Endmember-Modellierung erfolgreich getestet. Der Eisrückzug auf dem MacRobertson Schelf begann etwa 12,8 tausend kal. Jahre v. H. und war gegen 5,5 tausend kal. Jahre v. H. abgeschlossen. Während des Holozäns kam es zu starken Schwankungen in der Bodenwasseraktivität, die höchst wahrscheinlich mit der Neubildungsrate von Meereis in der Kap Darnley Polynia in Zusammenhang stehen. Besonders auffallend war eine erhöhte Bodenwasseraktivität am Übergang von Warm- zu Kaltphasen bzw. ihr extremer Rückgang während des Mittel-Holozänen Klimaoptimums. Insgesamt zeigen die Ergebnisse der Arbeit, dass sich das LAIS während des Quartärs relativ stabil gegenüber Klimaveränderungen verhalten hat. Die Bodenwasserproduktion in Polynien dagegen reagierte sehr empfindlich auf relative geringe atmosphärische Veränderungen und bedarf in Zukunft verstärkter Aufmerksamkeit.

Climate and environmental change following the retreat of the last glacial ice sheet in the Antarctic Peninsula has been interpreted, employing diatom abundance, relative abundance of Chaetoceros resting spores and diatom assemblages as proxies. These together with sedimentological data and radiocarbon dating, suggest four major events that can be further subdivided. Deglaciation ~13.2-11.5 kyr BP with ice shelf breakup and strong surface water stratification from melting ice. Climate reversal ~11.5-9.0 kyr BP with turbulent water masses. Climate optimum ~9.0-4.0 kyr BP with intrusions of northern ´warm` water masses. Neoglacial ~4.0 kyr BP-present with extended periods of sea ice cover and increased storm frequency. One aspect of climate change is the stability of marine based ice sheets, and the interaction with underlying sediment. A pilot study on characterizing sediment influenced by past ice streaming (Ross Sea) was performed using diatom, texture and chemical analysis. The results show that: Diamictons are chemically and texturally well homogenized, whereas diatom assemblages suggest different degrees of stratigraphic mixing and reworking related to mode of glacial sediment transport. Mud appears in different stratigraphic sections deposited in sub-ice shelf or ice edge environment, or through winnowing by currents. This is evident through stratigraphically-diverse diatom assemblages and texture. Most sediment characterized as mud is enriched in zinc (Zn). Hemipelagic diatomaceous muds are enriched in barium (Ba) and the diatom assemblage is dominated by typical neritic post-glacial species.