La variabilité de l’intensité du flux d’eaux atlantiques et de la nature des masses d’eau de surface le long des marges occidentales de la Norvège, de la mer de Barents et du Svalbard a été reconstituée sur la base des assemblages de coccolithes et dinokystes présents dans cinq carottes sédimentaires marines représentatives de l’Holocène terminal. Les résultats sont présentés sous la forme de reconstructions qualitatives et quantitatives (fonctions de transfert MAT) à haute résolution temporelle (échelle décennale à sub-séculaire). Un travail visantà valider les traceurs micropaléontologiques utilisés a été réalisé en parallèle à l’objectif principal, et s’est en particulier nourri de la collecte et de l’examen de populations vivantes distribuées le long de plusieurs transectszonaux en mer de Norvège, mer d’Islande et à travers le détroit de Fram.Nos résultats indiquent que la partie orientale des mers Nordiques (66 à 77°N) a été sujette à une tendance globale à l’augmentation du flux d’eaux atlantiques (AW) au cours des derniers 3000 ans. La dynamique récente de ce flux méridien est supposée répondre à la modulation long-terme de la force et de la localisation de la ceinture des vents d’ouest qui est essentiellement pilotée par l’Oscillation Nord Atlantique. Ce même mécanisme atmosphérique réconcilie le déplacement zonal et contradictoire du front arctique entre le domaine ouest-norvégien, et les façades occidentales de la mer de Barents et du détroit de Fram. La variabilité rapide du flux d’AW reproduit la succession des phases climatiques historiques classiques chaudes (Période Chaude Romaine, Période Chaude Médiévale, Période Moderne : flux accentué d’AW) et froides (Période Sombre, Petit Age Glaciaire : flux réduit d’AW) des derniers 2500 ans. Un événènement rapide de renforcement du flux d’AW en mers Nordiques a été identifié pendant le Petit Age Glaciaire entre 330 et 410 ans BP (cal.). Nos résultats indiquent que les variations d’intensité du flux d’AW vers l’Océan Arctique ont eu un impact majeur sur la distribution de la glace de mer arctique au cours du dernier millier d’années, les variations reconstruites de l’extension du couvert de glace à l’echelle de l’océan arctique étant parfaitement corrélées (échelle subséculaire) avec nos reconstructions qualitatives de la dynamique de l’AW au large du Svalbard et de la mer de Barents. La diminution importante de l’extension de la banquise durant le 20ème siècle est synchrone d’un flux record d’AW à travers le détroit de Fram, flux qui, d’après nos données, est sans précédent pour les derniers 3000 ans. / Five marine sediment cores distributed along the Norwegian, western Barents Sea, and Svalbard continental margins have been investigated in order to reconstruct late Holocene changes in the poleward flow of the Norwegian Atlantic Current (NwAC) and West Spitsbergen Current (WSC) and the nature of the upper surface water masses within the eastern Nordic Seas. This research project is based on the use of dinocyst and coccolith assemblages for qualitative and quantitative reconstructions of surface water conditions from high resolution sediment cores, and involve upstream investigations on proxy reliabilities. The investigated area (66 to 77°N) was affected by an overall increase in the strength of the AW flow from 3000 cal. yrs BP to the Present. The long-term modulation of westerlies strength and location which are essentially driven by the dominant mode of the North Atlantic Oscillation (NAO), is thought to explain the observed dynamics of the AW flow. The same mechanism also reconciles the recorded opposite zonal shifts in the location of the Arctic Front between the area off western Norway and the western Barents Sea-eastern Fram Strait region. Submillenial changes in AW flow are organised according to known pre-Anthropocene warm (RWP, MCA and the Modern period: strong poleward flow) and cold (LIA, DA: weak poleward flow) climatic spells. A sudden short pulse of resumed high WSC flow interrupted the LIA in the eastern Nordic Seas from 330 to 410 cal. yrs BP. Our results are indicative of a major impact of AW flow dynamics on the Arctic sea ice distribution during the last millenium, when changes in reconstructed sea-ice extent are negatively correlated with the strength of the WSC flow off western Barents Sea and western Svalbard. The extensive decrease in sea ice extent during the last century is synchronous with an exceptional increase in AW flow. The previously reconstructed high amplitude warming of surface waters in eastern Fram Strait at the turn of the 19th century was therefore primarily induced by an excess flow of AW which stands as unprecedented over the last 3000 years.

A região de Diamantina, em Minas Gerais, guarda um amplo acervo de grafismos rupestres e ricos conjuntos artefatuais e estruturas atribuíveis aos últimos 1.500 anos de ocupação humana. Esta pesquisa investiga os dois conjuntos de registros arqueológicos: o horizonte recente e as pinturas rupestres. Numa análise que procura congregar estudos intra e intersítios, os dois conjuntos são explorados, em busca de identificar sistemas de ocupação e construção da paisagem. Nas ocupações recentes, vêem-se coleções líticas bastante variadas, em sítios de atributos diferentes, que se pretende conectar por meio do emprego das noções de organização tecnológica e cadeia operatória. No que tange aos grafismos rupestres, esta pesquisa investe na identificação de estilos e no reconhecimento das relações cronológicas entre esses. São analisadas também as formas de interação diacrônica entre figuras e as formas de sua composição gráfica. / The region of Diamantina, in Minas Gerais, has a large rock paintings assemblage and rich artefactual assemblages, and structures from the last 1.500 years of human occupation. This research explores the both archaeological features: the occupations of the later pre-colonial period and the rock art. Trying to put together intra and inter-site studies, we intent to identify systems of landscape building. In the later human occupation, there are many lithic artifacts, in different kinds of sites, that are studied here with the use of two basic concepts: technological organization and chaine operatoir. The rock art is explored through stylistic and chronological approaches. We also explore the ways of diachronical interactions and graphic construction among the paintings.

Mid- and Late Holocene paleoceanographic changes over the S/SE Brazilian continental shelf have been accessed through a multi-proxy approach. Sedimetological, geochemical and microfaunal proxies were investigated in three high resolution marine sedimentary cores collected along the S/SE Brazilian shelf and discussed under a regional and global oceanographic and climatic perspective. The depositional processes of the S/SE Brazilian margin were submitted to two different hydrodynamic controls during Mid- and Late Holocene: (i) the northward penetration of the La Plata River Plume, bringing La Plata River derived sediments, and (ii) the high energetic Brazil Current onshore/offshore movements transporting SE Brazilian derived sediments for the northernmost part of the Santos Basin (25°S) during the Mid-Holocene. In the Late Holocene, especially after 3000 yr cal. BP, La Plata River derived sediments reached up to 25°S, highlighting a stronger influence of the La Plata River over the S/SE Brazilian shelf as a result of increase in precipitation over the La Plata River drainage basin. As the La Plata River colder and less saline waters influence over the S/SE Brazilian shelf increased, the oligotrophic waters of the shelf were fertilized, promoting enhancement of surface waters primary productivity and seafloor exportation. In the vicinity of 25°S, surface waters primary productivity was also enhanced by increase in colder and less saline South Atlantic Central Waters (SACW) shelf penetration. An overall a background trend of lower water temperature and salinities corroborates to a stronger influence of the La Plata River Plume waters during the Late Holocene as a result of higher precipitation over SE South America. This trend followed the summer insolation at 30°S, in accordance to other proxy records and numerical models. In the northernmost part of study area, superimposed to the general background trend, two major temperature and salinity negative incursions with abrupt contacts centered at 5500 yr cal. BP and after 2800 yr cal. BP highlight multi-centennial scale changes, possibly related to SACW shelf penetrations due to persistent NE winds. These changes occurred simultaneously to rapid climatic events at regional and global spatial scale. AMOC slowdown events, mediated by amplifying mechanisms, are the proposed triggering mechanism for the changes observed in the SE Brazilian shelf records. The amplifying mechanisms may have changed throughout time and as atmospheric teleconnections are not yet fully understood we hypothesize that different modes of climatic variability, such as ENSO and the South Atlantic dipole, may have acted as mediators during Mid- and Late Holocene. / Neste estudo uma visão multi-proxy foi aplicada na compreensão das mudanças nas condições oceanográficas em que a plataforma continental S/SE Brasileira foi submetida ao longo do Holoceno Médio e Tardio. Para isso proxies sedimentológicos, geoquímicos e microfaunísticos foram estudados em três testemunhos marinhos de alta resolução coletados ao longo da plataforma S/SE do Brasil e discutidos sob uma perspectiva oceanográfica e climática regional e global. No Holoceno Médio e Tardio, os processos deposicionais da plataforma S/SE Brasileira foram influenciados por dois processos hidrodinâmicos distintos: (i) a presença da Pluma do Rio La Plata, trazendo sedimentos oriundos da Bacia de drenagem do Rio La Plata, e (ii) os movimentos onshore/offshore da Corrente do Brasil, no Holoceno Médio, trazendo sedimentos oriundos da margem SE Brasileira para porção norte da Bacia de Santos (25°S). A zona de influência do Rio La Plata estendeu-se a latitudes mais ao norte atingindo 25°S, no Holoceno Tardio, especialmente nos últimos 3000 anos, como resultado do aumento nos regimes de precipitação sobre a Bacia de drenagem desse rio. As águas superficiais da plataforma S/SE Brasileira foram fertilizadas pelas águas mais frias e menos salinas da Pluma do Rio La Plata, disponibilizando mais matéria orgânica para o sistema bentônico. Nas proximidades de 25°S, a penetração na plataforma da Água Central do Atlântico Sul (ACAS) também promoveu aumento na produtividade primária das águas superficiais. Ao longo do Holoceno Médio e Tardio, uma tendência geral de diminuição da temperatura e salinidade das águas superficiais corrobora com uma maior influência da Pluma do Rio La Plata sobre a plataforma S/SE Brasileira como consequência de um aumento na precipitação no SE da América do Sul. Essa tendência segue a tendência da insolação de verão em 30°S, e concorda com outros registros proxy e modelos numéricos. Na porção norte da área de estudo, sobreposta à tendência geral, duas grandes incursões negativas temperatura e salinidade, com contatos abruptos, centradas em 5500 anos cal. BP e depois de 2800 anos cal. BP sugerem a ocorrência de mudanças de escala multi-centenárias, possivelmente relacionadas a penetração da ACAS na plataforma em decorrência de ventos de NE persistentes. Estas mudanças ocorreram simultaneamente a eventos rápidos climáticos em escala regional e global. Eventos de desaceleração da AMOC, mediada por mecanismos de amplificação, são propostos como o mecanismo responsável por desencadear estas mudanças (triggering mechanism). Os mecanismos amplificadores podem ter mudado ao longo do tempo e dado o não total entendimento das teleconexões atmosféricas do sistema climático, colocamos como hipótese que, no Holoceno Médio e Tardio, diferentes modos de variabilidade climática tais como, ENSO e dipolo do Atlântico Sul, podem ter atuado.

Mid- and Late Holocene paleoceanographic changes over the S/SE Brazilian continental shelf have been accessed through a multi-proxy approach. Sedimetological, geochemical and microfaunal proxies were investigated in three high resolution marine sedimentary cores collected along the S/SE Brazilian shelf and discussed under a regional and global oceanographic and climatic perspective. The depositional processes of the S/SE Brazilian margin were submitted to two different hydrodynamic controls during Mid- and Late Holocene: (i) the northward penetration of the La Plata River Plume, bringing La Plata River derived sediments, and (ii) the high energetic Brazil Current onshore/offshore movements transporting SE Brazilian derived sediments for the northernmost part of the Santos Basin (25°S) during the Mid-Holocene. In the Late Holocene, especially after 3000 yr cal. BP, La Plata River derived sediments reached up to 25°S, highlighting a stronger influence of the La Plata River over the S/SE Brazilian shelf as a result of increase in precipitation over the La Plata River drainage basin. As the La Plata River colder and less saline waters influence over the S/SE Brazilian shelf increased, the oligotrophic waters of the shelf were fertilized, promoting enhancement of surface waters primary productivity and seafloor exportation. In the vicinity of 25°S, surface waters primary productivity was also enhanced by increase in colder and less saline South Atlantic Central Waters (SACW) shelf penetration. An overall a background trend of lower water temperature and salinities corroborates to a stronger influence of the La Plata River Plume waters during the Late Holocene as a result of higher precipitation over SE South America. This trend followed the summer insolation at 30°S, in accordance to other proxy records and numerical models. In the northernmost part of study area, superimposed to the general background trend, two major temperature and salinity negative incursions with abrupt contacts centered at 5500 yr cal. BP and after 2800 yr cal. BP highlight multi-centennial scale changes, possibly related to SACW shelf penetrations due to persistent NE winds. These changes occurred simultaneously to rapid climatic events at regional and global spatial scale. AMOC slowdown events, mediated by amplifying mechanisms, are the proposed triggering mechanism for the changes observed in the SE Brazilian shelf records. The amplifying mechanisms may have changed throughout time and as atmospheric teleconnections are not yet fully understood we hypothesize that different modes of climatic variability, such as ENSO and the South Atlantic dipole, may have acted as mediators during Mid- and Late Holocene. / Neste estudo uma visão multi-proxy foi aplicada na compreensão das mudanças nas condições oceanográficas em que a plataforma continental S/SE Brasileira foi submetida ao longo do Holoceno Médio e Tardio. Para isso proxies sedimentológicos, geoquímicos e microfaunísticos foram estudados em três testemunhos marinhos de alta resolução coletados ao longo da plataforma S/SE do Brasil e discutidos sob uma perspectiva oceanográfica e climática regional e global. No Holoceno Médio e Tardio, os processos deposicionais da plataforma S/SE Brasileira foram influenciados por dois processos hidrodinâmicos distintos: (i) a presença da Pluma do Rio La Plata, trazendo sedimentos oriundos da Bacia de drenagem do Rio La Plata, e (ii) os movimentos onshore/offshore da Corrente do Brasil, no Holoceno Médio, trazendo sedimentos oriundos da margem SE Brasileira para porção norte da Bacia de Santos (25°S). A zona de influência do Rio La Plata estendeu-se a latitudes mais ao norte atingindo 25°S, no Holoceno Tardio, especialmente nos últimos 3000 anos, como resultado do aumento nos regimes de precipitação sobre a Bacia de drenagem desse rio. As águas superficiais da plataforma S/SE Brasileira foram fertilizadas pelas águas mais frias e menos salinas da Pluma do Rio La Plata, disponibilizando mais matéria orgânica para o sistema bentônico. Nas proximidades de 25°S, a penetração na plataforma da Água Central do Atlântico Sul (ACAS) também promoveu aumento na produtividade primária das águas superficiais. Ao longo do Holoceno Médio e Tardio, uma tendência geral de diminuição da temperatura e salinidade das águas superficiais corrobora com uma maior influência da Pluma do Rio La Plata sobre a plataforma S/SE Brasileira como consequência de um aumento na precipitação no SE da América do Sul. Essa tendência segue a tendência da insolação de verão em 30°S, e concorda com outros registros proxy e modelos numéricos. Na porção norte da área de estudo, sobreposta à tendência geral, duas grandes incursões negativas temperatura e salinidade, com contatos abruptos, centradas em 5500 anos cal. BP e depois de 2800 anos cal. BP sugerem a ocorrência de mudanças de escala multi-centenárias, possivelmente relacionadas a penetração da ACAS na plataforma em decorrência de ventos de NE persistentes. Estas mudanças ocorreram simultaneamente a eventos rápidos climáticos em escala regional e global. Eventos de desaceleração da AMOC, mediada por mecanismos de amplificação, são propostos como o mecanismo responsável por desencadear estas mudanças (triggering mechanism). Os mecanismos amplificadores podem ter mudado ao longo do tempo e dado o não total entendimento das teleconexões atmosféricas do sistema climático, colocamos como hipótese que, no Holoceno Médio e Tardio, diferentes modos de variabilidade climática tais como, ENSO e dipolo do Atlântico Sul, podem ter atuado.

The intracontinental endorheic Aral Sea, remote from oceanic influences, represents an excellent sedimentary archive in Central Asia that can be used for high-resolution palaeoclimate studies. We performed palynological, microfacies and geochemical analyses on sediment cores retrieved from Chernyshov Bay, in the NW part of the modern Large Aral Sea. The most complete sedimentary sequence, whose total length is 11 m, covers approximately the past 2000 years of the late Holocene. High-resolution palynological analyses, conducted on both dinoflagellate cysts assemblages and pollen grains, evidenced prominent environmental change in the Aral Sea and in the catchment area. The diversity and the distribution of dinoflagellate cysts within the assemblages characterized the sequence of salinity and lake-level changes during the past 2000 years. Due to the strong dependence of the Aral Sea hydrology to inputs from its tributaries, the lake levels are ultimately linked to fluctuations in meltwater discharges during spring. As the amplitude of glacial meltwater inputs is largely controlled by temperature variations in the Tien Shan and Pamir Mountains during the melting season, salinity and lake-level changes of the Aral Sea reflect temperature fluctuations in the high catchment area during the past 2000 years. Dinoflagellate cyst assemblages document lake lowstands and hypersaline conditions during ca. 0–425 AD, 920–1230 AD, 1500 AD, 1600–1650 AD, 1800 AD and since the 1960s, whereas oligosaline conditions and higher lake levels prevailed during the intervening periods. Besides, reworked dinoflagellate cysts from Palaeogene and Neogene deposits happened to be a valuable proxy for extreme sheet-wash events, when precipitation is enhanced over the Aral Sea Basin as during 1230–1450 AD. We propose that the recorded environmental changes are related primarily to climate, but may have been possibly amplified during extreme conditions by human-controlled irrigation activities or military conflicts. Additionally, salinity levels and variations in solar activity show striking similarities over the past millennium, as during 1000–1300 AD, 1450–1550 and 1600–1700 AD when low lake levels match well with an increase in solar activity thus suggesting that an increase in the net radiative forcing reinforced past Aral Sea’s regressions. On the other hand, we used pollen analyses to quantify changes in moisture conditions in the Aral Sea Basin. High-resolution reconstruction of precipitation (mean annual) and temperature (mean annual, coldest versus warmest month) parameters are performed using the “probability mutual climatic spheres” method, providing the sequence of climate change for the past 2000 years in western Central Asia. Cold and arid conditions prevailed during ca. 0–400 AD, 900–1150 AD and 1500–1650 AD with the extension of xeric vegetation dominated by steppe elements. Conversely, warmer and less arid conditions occurred during ca. 400–900 AD and 1150–1450 AD, where steppe vegetation was enriched in plants requiring moister conditions. Change in the precipitation pattern over the Aral Sea Basin is shown to be predominantly controlled by the Eastern Mediterranean (EM) cyclonic system, which provides humidity to the Middle East and western Central Asia during winter and early spring. As the EM is significantly regulated by pressure modulations of the North Atlantic Oscillation (NAO) when the system is in a negative phase, a relationship between humidity over western Central Asia and the NAO is proposed. Besides, laminated sediments record shifts in sedimentary processes during the late Holocene that reflect pronounced changes in taphonomic dynamics. In Central Asia, the frequency of dust storms occurring during spring when the continent is heating up is mostly controlled by the intensity and the position of the Siberian High (SH) Pressure System. Using titanium (Ti) content in laminated sediments as a proxy for aeolian detrital inputs, changes in wind dynamics over Central Asia is documented for the past 1500 years, offering the longest reconstruction of SH variability to date. Based on high Ti content, stronger wind dynamics are reported from 450–700 AD, 1210–1265 AD, 1350–1750 AD and 1800–1975 AD, reporting a stronger SH during spring. In contrast, lower Ti content from 1750–1800 AD and 1980–1985 AD reflect a diminished influence of the SH and a reduced atmospheric circulation. During 1180–1210 AD and 1265–1310 AD, considerably weakened atmospheric circulation is evidenced. As a whole, though climate dynamics controlled environmental changes and ultimately modulated changes in the western Central Asia’s climate system, it is likely that changes in solar activity also had an impact by influencing to some extent the Aral Sea’s hydrology balance and also regional temperature patterns in the past. <hr> The appendix of the thesis is provided via the HTML document as ZIP download. / Der Aralsee ist ein intrakontinental gelegenes endorheisches Gewässer fernab von ozeanischen Einflüssen, welches ein exzellentes sedimentäres Archiv für hochauflösende Paläoklimastudien in Zentralasien darstellt. In der vorliegenden Studie wurden umfangreiche palynologische, mikrofazielle und geochemische Analysen anhand von mehreren Bohrkernen aus der Chernyshov-Bucht im NW des heutigen Großen Aralsees durchgeführt. Die vollständigste der erbohrten Sequenzen weist dabei eine Länge von 11 m auf und beinhaltet näherungsweise die letzten 2000 Jahre des Holozän. Die hochauflösenden palynologischen Analysen der Studie, welche sowohl die Untersuchung von Dinoflagellatenzysten als auch Pollen beinhaltet, zeugen von einschneidenden Umweltveränderungen im Aralsee und seinem Einzugsgebiet. Die Untersuchung von Diversität und räumlicher Verbreitung der fossilen Dinoflagellatenzysten vermittelt dabei ein genaues Bild von den Salinitäts- und Seespiegeländerungen der letzten 2000 Jahre. Aufgrund der weitgehenden Abhängigkeit der hydrologischen Verhältnisse des Aralsees von der Wasserführung seinen tributären Flüsse, hängt sein Seespiegel unmittelbar von den Schmelzwasserzuflüssen im Frühjahr ab. Da der Schmelzwasserzufluss seinerseits mit den Temperaturveränderungen im Tien Shan und Pamir während der Schneeschmelze in Verbindung steht, spiegeln die Paläo-Salinität und der Paläo-Seespiegel des Aralsees folglich die Temperaturveränderungen im hochgelegenen Einzugsgebiet des Aralsees wider. Die Untersuchung der fossilen Dinoflagellatenzysten belegt besonders niedrige Seestände und hypersaline Bedingungen während der Perioden 0–425 AD, 920–1230 AD, 1500 AD, 1600 AD, 1800 AD und seit 1960, wohingegen oligohaline Bedingungen und höhere Seestände zwischen diesen Phasen dokumentiert sind. Ferner stellen umgelagerte Dinoflagellatenzysten aus Paläogenen und Neogenen Ablagerungen wertvolle Proxies für den Beleg von extremen Flächenspülereignissen dar, wie sie beispielsweise 1230–1450 AD aufgetreten und durch sehr hohe Niederschläge dokumentiert sind. Anhand der in der Studie erarbeiteten Daten ist davon auszugehen, dass die am Aralsee nachgewiesenen Umweltveränderungen im Wesentlichen von klimatischen Änderungen induziert wurden, durch historischen Bewässerungsfeldbau oder militärischen Konflikten jedoch noch verstärkt werden konnten. Darüber hinaus zeigen die Seestandsveränderungen eine sehr hohe Korrelation mit der Sonnenaktivität im letzten Jahrtausend, wie etwa während den Perioden 1000–1300 AD, 1450–1550 und 1600–1700 AD. Komplementär zu der Untersuchung von Dinoflagellatenzysten liefert die Pollenanalyse wertvolle Klimadaten für das Becken des Aralsees. Verschiedene Temperatur- (Jahresmittel, kältester gegen wärmster Monat) und Niederschlagsparameter wurden mit Hilfe der Methode der „probability mutual climatic spheres“ quantitative ausgewertet, womit die Klimaentwicklung im westlichen Zentralasien der letzten 2000 Jahre nachvollzogen werden konnte. Kalte und aride Bedingungen wiesen demnach die durch trockenangepasste Vegetation und Steppenelementen geprägten Perioden 0–400 AD, 900–1150 AD und 1500–1650 AD auf. Andererseits traten warme und weniger aride Klimabedingungen in den durch niederschlagsbedürftigere Pflanzen gekennzeichneten Zeiträumen 400–900 AD and 1150–1450 AD in den Vordergrund. Die Studie zeigt für das Becken des Aralsees, dass die Veränderungen im Niederschlagsmuster hauptsächlich vom zyklonalen System des östlichen Mittelmeergebietes (EM) gesteuert werden, welches den nahen Osten und das westliche Zentralasien mit Feuchtigkeit im Winter und Frühjahr versorgt. Da seinerseits das EM maßgeblich von Luftdruckänderungen der Nordatlantischen Oszillation (NAO) während seiner negativen Phase reguliert wird, ist ein Zusammenhang zwischen der Feuchtigkeit im westlichen Zentralasien und dem NAO anzunehmen. Außerdem belegen die laminierten Sedimente Veränderungen in den Sedimentationsprozessen während des späten Holozän, sowie ausgeprägte Änderungen im taphonomischen Verhalten. In Zentralasien hängt die Häufigkeit der im Frühjahr auftretenden Staubstürme hauptsächlich von der Intensität und der Position des Sibirienhochs (SH) ab. Der Gehalt an Titanium (Ti) als Proxy für äolischen Eintrag in den laminierten Sedimenten erlaubt die Rekonstruktion von winddynamischen Veränderungen in Zentralasien in den letzten 1500 Jahren. Die Studie beinhaltet daher die bislang längste Analyse der Variabilität des SH. Hohe Titaniumwerte sprechen für eine stärkere Winddynamik während den Perioden 450–700 AD, 1210–1265 AD, 1350–1750 AD und 1800–1975 AD, und dokumentieren demzufolge eine stärker ausgeprägtes SH während des Frühjahrs. Umgekehrt belegen geringe Titaniumwerte für die Zeit von 1180–1210 AD, 1265–1310 AD, 1750–1800 AD und 1980–1985 AD einen reduzierten Einfluss des SH.

A região de Diamantina, em Minas Gerais, guarda um amplo acervo de grafismos rupestres e ricos conjuntos artefatuais e estruturas atribuíveis aos últimos 1.500 anos de ocupação humana. Esta pesquisa investiga os dois conjuntos de registros arqueológicos: o horizonte recente e as pinturas rupestres. Numa análise que procura congregar estudos intra e intersítios, os dois conjuntos são explorados, em busca de identificar sistemas de ocupação e construção da paisagem. Nas ocupações recentes, vêem-se coleções líticas bastante variadas, em sítios de atributos diferentes, que se pretende conectar por meio do emprego das noções de organização tecnológica e cadeia operatória. No que tange aos grafismos rupestres, esta pesquisa investe na identificação de estilos e no reconhecimento das relações cronológicas entre esses. São analisadas também as formas de interação diacrônica entre figuras e as formas de sua composição gráfica. / The region of Diamantina, in Minas Gerais, has a large rock paintings assemblage and rich artefactual assemblages, and structures from the last 1.500 years of human occupation. This research explores the both archaeological features: the occupations of the later pre-colonial period and the rock art. Trying to put together intra and inter-site studies, we intent to identify systems of landscape building. In the later human occupation, there are many lithic artifacts, in different kinds of sites, that are studied here with the use of two basic concepts: technological organization and chaine operatoir. The rock art is explored through stylistic and chronological approaches. We also explore the ways of diachronical interactions and graphic construction among the paintings.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2016-08-01T16:21:23Z No. of bitstreams: 1 Briceño-Zuluaga 2016 Tese.pdf: 9025569 bytes, checksum: 00c4eb9cee0d346d7a8681fdbb975f49 (MD5) / Made available in DSpace on 2016-08-01T16:21:23Z (GMT). No. of bitstreams: 1 Briceño-Zuluaga 2016 Tese.pdf: 9025569 bytes, checksum: 00c4eb9cee0d346d7a8681fdbb975f49 (MD5) / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geociências - Geoquímica. Niterói, RJ / Este trabalho apresenta o registro da distribuição granulométrica de sedimentos laminados recuperados na plataforma continental de Pisco (Peru), que é caracterizada pelos aportes fluviais regionais (relacionado com aumento das precipitações) e pelo aporte eólico local (relacionado com a intensidade do vento local). Esse registro vai desde a Anomalia Climática Medieval (ACM) até o Período de Aquecimento Moderno (PAM) passando pela Pequena Idade do Gelo (PIG) numa escala secular até subdecadal. As simulações da distribuição e trajetórias atmosféricas do material eólico durante eventos registrados de erosão por tempestades de areia na região realizadas em Hysplit4 são apresentadas. Os resultados dessas simulações suportam o fato de que a origem eólica das partículas grosseiras ocorre no sedimento marinho. Os componentes granulométricos identificados são discutidos a partir do modelo matemático de fraccionamento de GOMES et al., (1990). Este modelo assume que a composição mineral dos sedimentos está composta por uma assembléia de diferentes populações de partículas minerais com distribuições granulométricas logarítmicas normais. Foi utilizada uma rotina interativa de mínimos quadrados para ajustar a distribuição granulométrica em uma expressão matemática que permite quantificar e identificar os diferentes componentes litológicos para depois inferir os mecanismos de transporte envolvidos e a variação espacial e temporal. O objetivo deste estudo foi separar os padrões de sedimentação do material terrígeno (eólico e fluvial) assim como os processos mais importantes que controlam à entrada deste material para entender como esses processos refletem a variabilidade climática e atmosférica durante o ultimo milênio. Nossos resultados mostram um ativo transporte de partículas eólicas durante a segunda metade da ACM com uma rápida diminuição da ACM para a PIG. Durante a PIG a erosão eólica exibe uma diminuição na sua atividade e assim, um enfraquecimento na intensidade do vento, ao mesmo tempo um incremento na descarga fluvial é apresentada e, isto se relaciona com um incremento na precipitação continental. Durante o PAM o transporte eólico apresenta um rápido e progressivo incremento em relação com o ACM e a PIG, enquanto que a aporte fluvial apresenta uma diminuição. Neste trabalho as simulações da distribuição e trajetórias do material eólico durante os eventos de erosão é apresentado. Comparações com outros registros paleoambientais indicam que essas mudanças estão vinculadas à mudanças no deslocamento meridional da Zona de Convergência Intertropical (ZCIT) e Alta Subtropical do Pacífico Sul (ASPS) assim como a atividade da circulação da célula de Walker em escala de tempo secular. Finalmente a deposição eólica e em consequência a intensidade do vento e sua variabilidade dos últimos 100 anos é muito mais forte que durante a ACM sob condições similares na posição do sistema ZCIT-ASPS. Esta tendência sugere uma forçante adicional na intensificação da circulação atmosférica, consistente com o atual padrão da Oscilação multidecadal do Atlantico e a tendência de aquecimento climático. / In this work are present record of laminated sediments cores retrieved in the continental shelf of Pisco (Peru) that characterize fluvial regional discharge and the wind local aeolian transport (related with the wind intensity) from Medieval Climate Anomaly (MCA) to Little Ice Age (LIA) and the current warm period (CWP) at centennial to sub-decadal resolution. The particle grain size components are discussed using a mathematical model of fractionation. This model assumes that lithological composition of the sediment is an assembled of several log-normally distributed particle population. In this way, an interactive least square fitting routine is used to fit the particle grain size collected with the mathematical expression. This allows inferring the spatial and temporal variation of particles populations and thus transport mechanisms involved. The aim of the study is unmixing and reconstructs the patters of terrigenous (aeolian and fluvial) sedimentation as well as the most important processes that control the input of this material to understand how these components reflect atmospheric climate variability during the last millennium. Our results presented in this work showed active aeolian erosion during the second half of the MCA and rapid decrease from the MCA to the LIA. During the LIA the aeolian erosion exhibit a decreased activity and them a weak in the atmospheric circulation on the same time an increase of fluvial discharge is showed this is relate with an increase of continental precipitation. During the CWP the aeolian erosion transport, display a rapid and progressive increase in relation to MCA and LIA, whereas the fluvial discharge exhibited a decrease. In this work simulation of the aeolian distribution and their trajectories during erosion events are also presented. Comparison with others records indicate that those changes are linked to change in the meridional position of the Intertropical convergence zone (ITCZ) and South Pacific Subtropical High (SPSH) at the centennial time resolution. Finally the CWP show increase in the aeolian deposition and thus in the wind intensity over the past two centuries likely represents the result of the modern position of the ITCZ–SPSH system and the associated intensification of the local and regional winds. Nevertheless, the aeolian deposition and in consequence the wind intensity and variability of the last 100 yr are stronger than the second sequence of the MCA under similar position of the ITZC-SPSH system. This trend suggests an additional forcing in the intensification of the atmospheric circulation, consistent with the current pattern of climate change.

xxi, 541 p. : ill. (some col.), maps. A print copy of this title is available through the UO Libraries under the call number: KNIGHT E78.O6 O37 2006 / Many archaeological researchers that have conducted investigations in the Harney Valley of southeastern Oregon use the ethnographic description of the seasonal round of the Harney Valley Paiute reported by Beatrice Blyth Whiting in her 1950 work Paiute Sorcery as a framework for discussions of prehistoric human use of the area. Archaeological investigations of seven sites, situated in areas identified as having been utilized by the Harvey Valley Paiutes, were conducted to test the relationship between Whiting's ethnographic account and the archaeological record. Data recovery excavations occurred at the Hoyt (35HA2422), Morgan (35HA2423) and Hines (35HA2692) sites near Burns, and test excavations occurred at the Knoll (35HA2530) site in the Silvies Valley, the RJ site (35HA3013) in the Stinkingwater Mountains, and the Broken Arrow (35HA2735) and Laurie's (35HA2734) sites near Malheur Lake. Studies of the cultural materials recovered during the excavations were undertaken to evaluate the content and complexity of each site. Analyses included typological considerations of the chipped stone tools, ground stone, bone tools, and shell, bone, and stone beads. Radiocarbon dating, obsidian sourcing and hydration, and zooarchaeological and paleobotanical analyses were also conducted when possible. Based on the results of the analyses, the seven sites reported herein were primarily used during the past 2000 years, with periods of less intensive use extending beyond 4000 BP. The results of the archaeological investigations indicate that there is a strong correlation between the late Holocene prehistoric record and Whiting's ethnographic description. However, the relationship between human use of the centrally-located lakes and wetlands and the neighboring uplands is clearly more complex than the ethnographic record suggests. Patterns of settlement and mobility revealed through the archaeological record indicate that central places, located closer to wetlands and lacustrine settings but within relatively easy reach of the uplands, may have figured more prominently in the behavior of prehistoric populations than the seasonal round as described by Whiting. Future research will benefit from explorations of central place foraging, emphasizing the role of behavioral ecology in the placement of sites and patterns of site use within the Harney Valley and the northern Great Basin at large. / Committee in Charge: Dr. C. Melvin Aikens, Chair; Dr. Dennis L. Jenkins; Dr. Douglas J. Kennett; Dr. Esther Jacobson-Tepfer

July temperature (TJUL) and total annual precipitation (ANNP) are reconstructed to better understand the spatial and temporal patterns of change in North America over the last 2,000 years using pollen databases. Using a customized application in R, the reconstructions use a composite averaging of multiple site reconstructions that show a distinct warmer Medieval Warm Period (MWP) compared to the colder Little Ice Age (LIA). Results show that, both multi-centennial scale periods are re- constructed as cooler than the last 50 years. Regional time series from several forested ecoregions show positive anomalies up to 0.6ºC during the MWP and anomalies up to -0.3ºC during the LIA. In order to test whether the TJUL reconstructions are biased to the modern calibration climate data, we show a distinct difference between the reconstructions when using station versus reanalysis-based modern TJUL fields. Reconstructions using station-based modern calibration data sets better reflect the centennial to multi-centennial scale climate variability as compared to the reanalysis-based modern calibration data sets that reveal a warm-bias. We justify the choice of the Whitmore et al. (2005) modern data set for large-scale pollen-based paleoclimate reconstructions. Finally we use Local Indicators of Spatial Association (LISA) to spatially filter the ANNP reconstructions in order to distinguish regional hydroclimate patterns from local site-specific conditions. Results show that a La Nina, positive North Atlantic Oscillation (+NAO) and positive Atlantic Multidecadal Oscillation (+AMO) state-like dominated both the MWP and Roman Warm Period (RWP), although the MWP was generally drier. In contrast, the Dark Ages Cold (DAC) period was likely dominated by El Nino, negative NAO and negative AMO state-like circulation. Minimum solar and high volcanic activity is likely to have contributed to more complex hydroclimate regional patterns during the LIA. The results presented in this dissertation can be used as benchmark data sets for future climate data-model comparisons in order to improve our understanding of natural climate variability during the past 2,000 years in the context of modern human-induced climate change.

Dans le désert Libyque (Égypte), l'un des plus arides du monde, l'action du vent trouvant peu de limites, l'ablation et le transport éoliens sont des éléments prégnants de la morphogenèse. Au cœur de ce désert, les oasis de la dépression de Kharga, nées de l'artésianisme et des activités humaines, constituent au contraire, par la profusion de l'eau et de la végétation, des secteurs où les processus de dépôt sont renforcés. L'imbrication entre une région désertique (zone-source de sédiments) et des sites oasiens (zones de dépôt), où s'appliquent des processus opposés, maximise les dynamiques éoliennes et leur impact morphogénétique. Il en découle la formation des paysages du vent, que cette thèse vise à décrire, comprendre et expliquer. Mobilisant des méthodes de géomorphologie, de géoarchéologie, de géohistoire et de sédimentologie, ce travail rend compte de l'impact paysager des interactions entre activités humaines et dynamiques éoliennes depuis la création des oasis il y a 2 500 ans. Il présente un bilan des processus naturels et anthropiques, et aborde la question des conditions de vie des oasiens depuis l'Antiquité.Trois apports principaux résultent de cette recherche :- une typologie des formations constitutives des paysages du vent- une modélisation descriptive du système à leur origine, reposant sur des cycles asynchrones de colonisation et de déprises- un bilan des grandes tendances de l'évolution environnementale et morphogénétique sur le temps long, depuis l'implantation des oasis : les paysages du vent sont nés de la distorsion entre la dégradation environnementale régionale et l'amélioration locale et temporaire des conditions édaphiques résultant des activités humaines. / The limiting features of the wind dynamics are scarce in the Western desert of Egypt, one of the most arid areas in the world: eolian ablation and transport are the prevailing factors of the morphogenesis. Born from artesian waters and human activities, the oases of Kharga basin form an area where the deposition processes are stronger thanks to the large amount of water and vegetation. Eolian dynamics, and their morphogenetic impacts, are strengthened by the nesting of oasis sites (deposition areas) in a desert region (sediment source-zone). The landscapes of the wind are thus formed by the juxtaposition of these areas where opposed processes occur. This thesis aims to describe, understand and explain their development.This work based on geomorphology, geoarchaeology, « géohistoire » and sedimentology gives an account on the impacts on the landscapes of the interactions between eolian dynamics and human activities since the creation of the oases 2 500 years ago. It consists in an overview of the natural and anthropogenic processes and an assessment of the living conditions in the oasis since the Antiquity.The three main results of this research are:- a typology of the elements forming the landscapes of the wind;- a descriptive modelisation of the system at stake in their formations, which is based on an asynchronous cycle of colonisation and abandonment of the sites;- an overview of the main patterns of the long-term environmental and morphogenetic evolution since the creation of the oases.This triple contribution shows that the landscapes of the wind are born from the distortion between the regional environmental trend towards degraded conditions and the local and temporary improvements of the edaphic conditions due to human activities.