Charwell Basin is a 6 km-wide structural depression situated at the boundary between the axial ranges and faulted and folded Marlborough Fault Zone of north-eastern South Island, New Zealand. The basin contains the piedmont reach of the Charwell River, and a series of late Quaternary loess-mantled alluvial terraces and terrace remnants that have been uplifted and translocated from their sediment source due to strike-slip motion along the Hope Fault which bounds the basin to its immediate north. The aim of this study was to provide an interdisciplinary, integrated and holistic analysis of late Quaternary landscape evolution and environmental change in Charwell Basin using terrain analysis, loess stratigraphy, soil chemistry and paleoecological data. The study contributes new understanding of New Zealand landscape and ecosystem responses to regional and global climatic change extending to Marine Isotope Stage (MIS) 6, and shows that climatically-forced shifts in biogeomorphic processes play a significant role in lowland landscape evolution. Morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time, with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo-concave land elements. Paleotopographic analysis of a &gt150 ka terrace mantled by up to three loess sheets revealed multiple episodes of alluvial aggradation and degradation and, subsequent to river abandonment, gully incision prior to and coeval with loess accumulation. Spatial heterogeneity in loess sheet preservation showed a complex history of loess accumulation and erosion. A critical profile curvature range of -0.005 to -0.014 (d2z/dx2, m-1) for loess erosion derived from a model parameterised in different ways successfully predicted loess occurrence on adjacent slope elements, but incorrectly predicted loess occurrence on an older terrace remnant from which all loess has been eroded. Future analyses incorporating planform curvature, regolith erosivity and other landform parameters may improve identification of thresholds controlling loess occurrence in Charwell Basin and in other South Island landscapes. A loess chronostratigraphic framework was developed for, and pedogenic phases identified in, the three loess sheets mantling the &gt150 ka terrace. Except for one age, infrared-stimulated luminescence dates from both an upbuilding interfluve loess exposure and colluvial gully infill underestimated loess age with respect to the widespread Kawakawa/Oruanui Tephra (KOT; 27,097 ± 957 cal. yr BP), highlighting the need for improvements in the methodology. Onset of loess sheet 1 accumulation started at ca. 50 ka, with a break at ca. 27 ka corresponding to the extended Last Glacial Maximum (eLGM) interstadial identified elsewhere in New Zealand. Loess accumulation through MIS 3 indicates a regional loess flux, and that glaciation was not a necessary condition for loess generation in South Island. Loess accumulation and local alluvial aggradation are decoupled: the youngest aggradation event only covers ~12 kyr of the period of loess sheet 1 accumulation. Older local aggradation episodes could not be the source because their associated terraces are mantled by loess sheet 1. In the absence of numerical ages, the timing of L2 and L3 accumulation is inferred on the basis of an offshore clastic sediment record. The upbuilding phase of loess sheet 2 occurred in late MIS 5a/MIS 4, and loess sheet 3 accumulated in two phases in MIS 5b and late MIS 6. Biogenic silica data were used to reconstruct broad shifts in vegetation and changes in gully soil saturation status. During interglacial/interstadial periods (MIS 1, early MIS 3, MIS 5) Nothofagus¬-dominated forest covered the area in association with Microlaena spp grasses. Lowering of treeline altitude during glacial/stadial periods (MIS 2, MIS 3, MIS 5b, late MIS 6) led to reduction in forest cover and a mosaic of shrubs and Chionochloa spp, Festuca spp and Poa spp tussock grasses. Comparison of interfluve and gully records showed spatial heterogeneity in vegetation cover possibly related to environmental gradients of exposure or soil moisture. A post-KOT peak in gully tree phytoliths corresponds to the eLGM interstadial, and a shift to grass-dominated vegetation occurred during the LGM sensu stricto. Diatoms indicated the site became considerably wetter from ca. 36 ka, with peak wetness at ca. 30, 25 and 21 ka, possibly due to reduced evapotranspiration and/or increased precipitation from a combination of strengthened westerly winds and increased cloudiness, or strengthened southerly flow and increased precipitation. Human influence after ca. 750 yr BP led to re-establishment of grassland in the area, which deposited phytoliths mixed to 30 cm depth in the soil. A coupled gully colluvial infilling/vegetation record showed that sediment flux during the late Pleistocene was ~0.0019 m3 m-1 yr-1 under a shrubland/grassland mosaic, and Holocene sediment flux was ~0.0034 m3 m-1 yr-1 under forest. This increase of 60% through the last glacial-interglacial transition resulted from increased bioturbation and down-slope soil transport via root growth and treethrow, which formed a biomantle as evidenced by slope redistribution of the KOT. These results contrast with sediment transport rates and processes hypothesised to occur contemporaneously in adjacent mountain catchments. This suggests that intraregional biogeomorphic processes can differ significantly depending on topography and geological substrate, with different landscapes responding in unique ways to the same climate shifts. Analysis of Quaternary terrestrial landscape evolution in non-glaciated mountainous and lowland areas must therefore consider spatial and temporal heterogeneity in sediment fluxes and underlying transport processes.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 245-266.

Made available in DSpace on 2014-06-11T19:27:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-02-04Bitstream added on 2014-06-13T18:56:34Z : No. of bitstreams: 1 arruda_em_me_rcla.pdf: 5956567 bytes, checksum: ed468990b15b939b7622d4e881ceacd3 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O trabalho aqui apresentado se insere no contexto do projeto temático História da Exumação da Plataforma Sul-americana, o exemplo da região Sudeste brasileira: termocronologia por traços de fissão e sistemáticas Ar/Ar e Sm/Nd, e tem como coordenador geral, o Prof. Dr. Peter Christian Hackspacher do Departamento de Petrologia e Metalogenia do IGCE/UNESP-Rio Claro, sendo financiado pela FAPESP (Processo n.º 00/03960-5). Esta pesquisa teve como objetivo analisar os eventos deposicionais, esculturadores do relevo, na bacia do Ribeirão Entupido, Serra da Mantiqueira, Estado de São Paulo, a partir do estudo morfoestratigráfico dos depósitos recentes da área. As feições deposicionais registradas em campo foram analisadas visando à definição de áreas tipo para coleta de amostras. Análises de datação foram realizadas com o material amostrado. As relações de conectividade entre as unidades deposicionais foram testadas a partir dos resultados de análises sedimentológicas e granulométricas. As análises foram enriquecidas pela datação absoluta do material sedimentar por LOE (Luminescência Opticamente Estimulada) do quartzo e do feldspato. O cruzamento de dados relativos às diversas técnicas aplicadas forneceu subsídios para a compreensão dos mecanismos que comandam a morfogênese na bacia em foco ao longo do último milhão de anos. / The research presented here inserts in the context of the thematic project History of the Exhumation of the South American Platform in the southeastern Brazil: Thernochronology by Fission Track Analysis and Ar/Ar and Sr/Nd systematics, and it has as general co-ordinating Prof. Dc. Peter Christian Hackspcher from IGCE/Unesp - Rio Claro, at the Department of Petrology and Metallogy, being financed for FAPESP (Process nº 00/03960-5). This research had as objective to analyze the depositionals events, sculpture of the relief, at the River Entupido's basin, Mantiqueira's Sierra, State of São Paulo, from the morphostratigraphic study of the recent deposits of the area. The main found and registered in field had been analyzed aiming at to the definition of areas type for collection of samples. Analyses of dating were realized through the showed sample. The relations of connection among the main units had been tested from the results of sendimentological and granulometrics analyses. The analyses had been enriched by the absolute dating of the sedimentary material by OSL (Optically Stimulated Luminescence) of the quartz and the feldspar. The data were compared many ways of techniques and gave us subsidies to insight of the mechanisms that commands morphogenesy in the basin analyzed the last million of years.

Resumo: O trabalho aqui apresentado se insere no contexto do projeto temático "História da Exumação da Plataforma Sul-americana, o exemplo da região Sudeste brasileira: termocronologia por traços de fissão e sistemáticas Ar/Ar e Sm/Nd", e tem como coordenador geral, o Prof. Dr. Peter Christian Hackspacher do Departamento de Petrologia e Metalogenia do IGCE/UNESP-Rio Claro, sendo financiado pela FAPESP (Processo n.º 00/03960-5). Esta pesquisa teve como objetivo analisar os eventos deposicionais, esculturadores do relevo, na bacia do Ribeirão Entupido, Serra da Mantiqueira, Estado de São Paulo, a partir do estudo morfoestratigráfico dos depósitos recentes da área. As feições deposicionais registradas em campo foram analisadas visando à definição de áreas tipo para coleta de amostras. Análises de datação foram realizadas com o material amostrado. As relações de conectividade entre as unidades deposicionais foram testadas a partir dos resultados de análises sedimentológicas e granulométricas. As análises foram enriquecidas pela datação absoluta do material sedimentar por LOE (Luminescência Opticamente Estimulada) do quartzo e do feldspato. O cruzamento de dados relativos às diversas técnicas aplicadas forneceu subsídios para a compreensão dos mecanismos que comandam a morfogênese na bacia em foco ao longo do último milhão de anos. / Abstract: The research presented here inserts in the context of the thematic project "History of the Exhumation of the South American Platform in the southeastern Brazil: Thernochronology by Fission Track Analysis and Ar/Ar and Sr/Nd systematics", and it has as general co-ordinating Prof. Dc. Peter Christian Hackspcher from IGCE/Unesp - Rio Claro, at the Department of Petrology and Metallogy, being financed for FAPESP (Process nº 00/03960-5). This research had as objective to analyze the depositionals events, sculpture of the relief, at the River Entupido's basin, Mantiqueira's Sierra, State of São Paulo, from the morphostratigraphic study of the recent deposits of the area. The main found and registered in field had been analyzed aiming at to the definition of areas type for collection of samples. Analyses of dating were realized through the showed sample. The relations of connection among the main units had been tested from the results of sendimentological and granulometrics analyses. The analyses had been enriched by the absolute dating of the sedimentary material by OSL (Optically Stimulated Luminescence) of the quartz and the feldspar. The data were compared many ways of techniques and gave us subsidies to insight of the mechanisms that commands morphogenesy in the basin analyzed the last million of years. / Orientador: Iandara Alves Mendes / Coorientador: Antônio Carlos de Barros Corrêa / Banca: Peter Christian Hackspacher / Banca: Cenira Maria Lupinacci da Cunha / Mestre

Idades por luminescência opticamente estimulada foram obtidas nos depósitos eólicos do litoral leste maranhense. As datações permitiram reconhecer ao menos quatro gerações de dunas eólicas, incluindo a atual. As duas gerações mais antigas (G1/G0: idades LOE de 258,9±24,6 a 88,0±8,6 ka A.P.) não são distinguíveis por critérios de campo, somente por dados geocronológicos. A geração eólica 2 corresponde a feições eólicas estabilizadas pela vegetação que ocorrem a até 135 km da linha de costa atual. As idades LOE-SAR de estabilização obtidas para essas feições eólicas compreendem um intervalo estreito de tempo (19 a 14 ka A.P.) no Pleistoceno superior. Essa fase estabilização do sistema eólico é correlacionada com o evento climático HS-1. Durante esse período no leste maranhense, sob maior influência da Zona de Convergência Intertropical pelo seu deslocamento para sul, ocorreu diminuição da intensidade dos ventos alísios e aumento da precipitação. Essas variações climáticas diminuíram a capacidade de transporte eólico e levou o sistema à estabilização. A análise de proveniência sedimentar com base em minerais pesado identificou como principal fonte sedimentar do litoral leste maranhense a plataforma continental localizada a leste da foz do rio Parnaíba, alimentada via deriva litorânea longitudinal para oeste. O rio Parnaíba aparentemente tem contribuição minoritária como fonte sedimentar, tanto para o sistema atual como para as gerações eólicas pretéritas. A dinâmica sedimentar do sistema eólico atual, evidenciada por minerais pesados, granulometria e parâmetros morfoplanimétricos, aponta para intenso retrabalhamento por rios que o limitam parcialmente ao interior e por drenagens intermitentes, de caráter entrelaçado, que o atravessam. O estudo do método de datação LOE e as características LOE dos sedimentos de diferentes localidades do Brasil permitiu identificar a boa aplicabilidade do método vista a alta sensibilidade LOE do quartzo e bom desempenho nos testes aplicados. A sensibilidade LOE do quartzo foi identificada como a principal característica determinante da qualidade da datação LOE. A proposição da razão de sensibilidade Quartzo-\"Al IND.2\'\'O IND.3\':C (\'delta\'\'POTs\' Q) permitiu tanto a padronização do cálculo da sensibilidade LOE como a comparação de medidas interlaboratoriais. A observação de grandes variações nos valores de sensibilidade LOE de quartzo para sedimentos de diferentes localidades são resultado tanto das rochas fonte como dos ciclos de sedimentação e retrabalhamento. A identificação de diferentes proveniências sedimentares com base no uso da sensibilidade LOE foi aplicada, com sucesso, na análise de variações climáticas baseada em mudanças de proveniência sedimentar na Ilha Comprida -SP. / Optically stimulated luminescence (OSL) ages were obtained in eolian deposits from the east coast of Maranhão, Brazil. OSL dating allowed the identification of at least four generations of eolian dunes, including the active dunefields. The two oldest generations (G1/G0: OSL ages 258.9±24.6 to 88.0±8.6 ky B.P.) are not distinguishable by field criteria, only geochronological data. Generation 2 corresponds to eolian features stabilized by vegetation that occurs up to 135 km from the current coast line. OSL-SAR ages of stabilization of these features are between 19 and 14 ky B.P., a narrow time interval during Pleistocene. This event is related to the climatic event HS-1. During this period the intensity of trade winds decreased and precipitation increased in the area due to a greater influence of the Intertropical Covergence Zone, which was shifting south. These climatic variations reduced the capacity of eolian transportation and the led system to to stabilization. Provenance analyzes by heavy minerals identified the continental shelf located east of the Parnaiba river mouth as sedimentary source for the east coast of Maranhão, which is fed by longitudinal litoral drift to west. Parnaiba river apparently has a minor contribution as sedimentary source for recent and past eolian generations. Sedimentary dynamic of the recent eolian system, as indicated by heavy minerals analyzes, grain size analyzes and morphoplanimetric parameters, is characterized by strong reworking by rivers, braided intermittent drainages, that cross the dunefield. All analyzed Brazilian sediments presented relatively high OSL sensitivity and good behavior regarding their luminescence characteristics relevant for radiation dose estimation. The OSL sensitivity of quartz was identified as the main characteristic interfering the OSL dating quality. We propose to standardize the definition of quartz OSL sensitivity using the Quartz-to-\'Al IND.2\'\'O IND.3\':C sensitivity ratio (\'delta\'\'POT.s\'Q). The standardization is a prerequisite to compare data obtained under different measurement conditions and to investigate and develop geological applications of quartz OSL sensitivity. We observed that the major factor controlling the OSL sensitivity is the sedimentary history of the sediment. Longer sedimentary transport provided by huge drainage systems and long-distance littoral drift increases the OSL sensitivity. The use of OSL sensitivity as provenance proxy was successfully applied at Ilha Comprida-SP to analyze climate variations.

Submarine canyons are major geomorphic features, transporting large quantities of sediments from land to the deep sea. These sediments contain nutrients, enabling life in the deep sea and potentially forming hydrocarbon reservoirs. The transport of sediments towards the deep sea is also important as it links into fundamental concepts of the Earth’s system, such as the global carbon cycle and land surface denudation. Concepts based on the assumption of direct transport of sediments from land to the deep sea. However, how this transport occurs, on what timescales, and if there is potential storage of sediments along the way, is actually poorly known. The current theory is that gravity flow events, such as turbidity events, are the main mechanism behind canyon formation and maintenance. Luminescence dating, an absolute dating method, has been used in an earlier study to look at sediment transport via turbidity currents down the Monterey Canyon, off the coast of California, USA (Stevens et al., 2014). An active upper canyon was found at 1093 metres depth, with frequent events. At 3555 and 3612 metres depth the turbidity events dated were older and indications of major reworking of sediments were found. To pinpoint this change in environments, the present study used luminescence dating in order to get an age estimate of sediments at 2920 meter depth, creating a sequence of ages in the canyon. These cores have captured sediments that have been transported via sand waves, not turbidites. Sand waves are related to the frequent passing of turbidity events, but exact understanding of the mechanisms at hand is poorly understood. Single grain analysis on quartz is used to obtain the individual properties and ages of grains. This gives representative canyon entry ages of the sediments in addition to intrinsic grain properties. The data shows a skewed distribution of grain ages with a narrow, dominant peak between 180 and 240 years within a single core, indicating frequent flushing events and minor reworking of sediments. This is a similar pattern to the core at 1093 meter depth, albeit with increased age, suggesting temporary storage of sediment to at least a depth of 2920 metres. It is proposed that there is a gradual increase in ages down canyon towards 2900 meters depth with a more abrupt transition in environments with increased storage of sediments between 2900 and 3500 meter depth. Sand waves, and the exact relation to turbidites, remain a poorly understood transport mechanisms, but are potentially capable to transport vast amounts of sediments towards the deep sea. / Marina raviner transporterar stora mängder sand från land till havets botten. Men hur sker detta? I nuläget förklaras sandtransport med gravitationsflöde, att gravitationen drar ner sandkornen mot bottnen. Men sker detta vid ett enda stort skede eller i små gradvisa steg? Och kan det vara så att sand, på sin väg till botten, lagras i ravinerna? Det är dessa frågor som jag försöker att kasta ljus på i och med detta projekt.Målet var att komplettera vår kunskap om hur sand förflyttar sig från land till havsbotten genom att studera ifall det har skett en gradvis eller en abrupt transport av sand i ravinen Monterey Canyon vid Kaliforniens kust. Detta har jag gjort genom att datera åldern av sand vid ett djup av 2 920 meter, som i det här fallet deponerats av sandvågor, och sedan jämfört denna ålder med åldrarna på sanden från ett mindre (1 100 m) och större (3 500 m och djupare) djup, vilka analyserades i en tidigare studie (Stevens et al., 2014). Transportmekanism i den studien skiljer sig med min då det rör sig om gravitationsflöden.Med endast några få sandkorn av annan ålder så var den dominerande åldern på kornen i mitt prov mellan 180 till 240 år gamla. Provet vid 1 100 m djup visade sig också ha en liten spridning av ålder vilket tyder på att det skett återkommande utspolning av gammal sand som istället ersatts av ny. Man kan se att det ändå sker en tillfällig lagring av sediment mellan det minsta, studerade djupet och det nyligen tagna provet på 2 900 m, då en svag ökning i ålder kan mätas. Åldern på sandkornen i proven som kom från ett större djup var istället mycket spridd och generellt mycket högre än de från mindre djup. Att det finns en mix av ålder vid ett och samma djup tyder på att sanden vid återkommande tillfällen omfördelats i ravinen.Denna studie antyder att ravinen i fråga är aktiv upp till ett djup av minst 2 920 meter, med bara en svag stegring i ålder med ökande djup. Mellan 2 920 och 3 500 meter ändras miljön vilket gör att sprid-ningen av ålder ökar. Därutöver var det nya provet taget från en plats med ett annorlunda transport-mekanism, sandvågor istället för gravitationsflöde. Sandvågor, och dess relation till gravitationsflöden, är fortsättningsvis en dåligt förstådd transportmekanism som potentiellt är kapabel till att flytta stora mängder sediment till havets botten.

<p>Еолски седименти представљају идеалан материјал за примену методе луминесцентног датирања. Један од главних разлога је њихов минеролошки састав који углавном чине кварц и фелдспат. Ови минерали поседују читав низ луминесцентних карактеристика који их чине погодним за луминесцентно датирање а поред тога, могуће је релативно једноставно извршити њихову екстракцију и сепарацију од других неминералних састојака. У случају лесних платоа (еолски транспортованих седимената), може се претпоставити да су индивидуална минерална зрна била потпуно изложена сунчевој светлости и да су у довољној мери ресетована пре депозиције. Истраживана секција Велики сурдук на Тителском лесном платоу, изабрана је за датирање, на основу своје моћности, високе стопе седиментације и комплетности које овај локалитет чине најдетаљнијим палеоклиматским архивом последња два глацијално- интерглацијална циклуса у овом делу Европе.<br />Употребом класичног SAR протокола за датирање утврђено је да кварцна зрна са<br />Тителског лесног платоа представљају прецизне дозиметре до ~120 Gy, после чега долази до очигледног засићења сигнала. Највиша утврђена доза фелдспата измерена модификованим SAR пост-IRIR^200,290 протоколом је била 854,0&plusmn;24 Gy. Пост-IRIR^200,290 протокол није утврдио сатурацију код минералних зрна фелдспата, што је умногомо подигло поуздану старосну границу за датирање на секцији Велики сурдук, а највероватније и на осталим лесним профилима у Србији. Примена различитих протокола и мерења аплицираних на различите групе минерала и њихове фракције дају овим истраживањима далекосежан методолошки значај. На овај начин је доказано да у поменутом временском опсегу OSL датирање грубог кварца даје поуздане старосне процене до 35,8&plusmn;3,7 ka док су зрна фелдспата датирана до чак 237,7&plusmn;12,8 ka. Кварц има апсолутно највећу подударност са очекиваним геолошким временом до MIS 2 за разлику од фелдспата који показује бoљу подударност са претпостављеном геолошком хронологијом до MIS 7.</p> / <p>Eolski sedimenti predstavljaju idealan materijal za primenu metode luminescentnog datiranja. Jedan od glavnih razloga je njihov minerološki sastav koji uglavnom čine kvarc i feldspat. Ovi minerali poseduju čitav niz luminescentnih karakteristika koji ih čine pogodnim za luminescentno datiranje a pored toga, moguće je relativno jednostavno izvršiti njihovu ekstrakciju i separaciju od drugih nemineralnih sastojaka. U slučaju lesnih platoa (eolski transportovanih sedimenata), može se pretpostaviti da su individualna mineralna zrna bila potpuno izložena sunčevoj svetlosti i da su u dovoljnoj meri resetovana pre depozicije. Istraživana sekcija Veliki surduk na Titelskom lesnom platou, izabrana je za datiranje, na osnovu svoje moćnosti, visoke stope sedimentacije i kompletnosti koje ovaj lokalitet čine najdetaljnijim paleoklimatskim arhivom poslednja dva glacijalno- interglacijalna ciklusa u ovom delu Evrope.<br />Upotrebom klasičnog SAR protokola za datiranje utvrđeno je da kvarcna zrna sa<br />Titelskog lesnog platoa predstavljaju precizne dozimetre do ~120 Gy, posle čega dolazi do očiglednog zasićenja signala. Najviša utvrđena doza feldspata izmerena modifikovanim SAR post-IRIR^200,290 protokolom je bila 854,0&plusmn;24 Gy. Post-IRIR^200,290 protokol nije utvrdio saturaciju kod mineralnih zrna feldspata, što je umnogomo podiglo pouzdanu starosnu granicu za datiranje na sekciji Veliki surduk, a najverovatnije i na ostalim lesnim profilima u Srbiji. Primena različitih protokola i merenja apliciranih na različite grupe minerala i njihove frakcije daju ovim istraživanjima dalekosežan metodološki značaj. Na ovaj način je dokazano da u pomenutom vremenskom opsegu OSL datiranje grubog kvarca daje pouzdane starosne procene do 35,8&plusmn;3,7 ka dok su zrna feldspata datirana do čak 237,7&plusmn;12,8 ka. Kvarc ima apsolutno najveću podudarnost sa očekivanim geološkim vremenom do MIS 2 za razliku od feldspata koji pokazuje bolju podudarnost sa pretpostavljenom geološkom hronologijom do MIS 7.</p> / <p>Aeolian sediments represent an ideal material for the application of the luminescence dating method. One of the main reasons is their mineralogical composition which consists mainly of quartz and feldspars. These minerals possess a whole range of luminescence characteristics that make them suitable for luminescence dating, and in&nbsp;&nbsp; addition, it is relatively easy to extract and separate them from other non-mineral ingredients. In the case of loess plateaus (eolically transported sediments), it can be assumed that individual mineral grains were completely exposed to sunlight and were sufficiently bleached before deposition. The investigated section Veliki surduk on the Titel loess plateau was chosen for dating, based on its thicknes, the high rate of sedimentation and completeness which makes this site one of the most detailed paleoclimatic archives of the last two glacial and interglacial cycles in this part of Europe.<br />Using the classic SAR protocol for dating, it has been found that the quartz grains from the Titel loess plateau are precise dosimeters up to ~120 Gy, followed by an apparent saturation of the signal. The highest established dose of feldspars measured by the modified SAR postIRIR^200,290 protocol was 854.0&plusmn;24 Gy. The post-IRIR^200,290 protocol did not determine the saturation of feldspar minerals, which has largely raised the age limit for luminescence dating at the Veliki surduk section, and most probably, also on other loess profiles in Serbia. The application of various protocols and measurements applied to different groups of minerals and their fractions give these research a far-reaching methodological significance. In this way, it has been proven that in the mentioned time range, OSL dating of coarse grain quartz yields reliable age estimates up to 35.8&plusmn;3.7 k while the feldspar grains are dated to as high as 237.7&plusmn;12.8 ka. Quartz has the highest match with the expected geological age to MIS 2 as opposed to feldspar, which shows better correspondance with the assumed geological chronology to MIS 7.</p>

Notre travail s'inscrit dans une dynamique de documentation de l'ouest du continent africain où les recherches en Préhistoire sont encore peu développées en comparaison du reste du continent. Nous avons cherché à établir un cadre chrono-culturel des gisements préhistoriques de la vallée de la Falémé, localisée à l'extrême Est du Sénégal, en y appliquant la méthode de datation par OSL. 86 échantillons ont ainsi été prélevés et datés, sur une vingtaine de sites répartis le long de la vallée. Grâce à des enregistrements sédimentaires relativement continus, nous avons documenté la chronologie des différents techno-complexes lithiques en présence. Des industries acheuléennes ont été datées d'au moins 90 ka, celles du Middle Stone Age notamment caractérisées par des industries à pièces bifaciales, se situent au MIS3. Quant aux industries caractéristiques du Late Stone Age (microlithiques et microlithiques géométriques), elles prennent place entre 15 et 10 ka avant le présent. La nécessité de documenter la chronologie des cultures préhistoriques nous a également poussé à réaliser des développements méthodologiques. Pour caractériser la micro-dosimétrie de nos échantillons, nous avons utilisé plusieurs techniques telles que l'imagerie (autoradiographe ᵦ) et la simulation numérique (DosiVox-2D). Ces travaux ont entre autres montré que les modèles communément employés ont tendance à biaiser le débit de dose et par conséquent les âges. À l'issue de notre travail, la vallée de la Falémé se présente donc comme une nouvelle séquence de référence pour la Préhistoire ouest africaine, aux côtés des travaux réalisés sur le complexe d'Ounjougou au Mali. / Our work is part of a West African Prehistory documentation dynamic. Compared to other regions of this continent, research in this area is still scarce. Our aim was to establish a chrono-cultural framework of the Falémé Valley archaeological sites located in Eastern Senegal by applying the OSL dating method. For this purpose, 86 samples were taken and dated from around 20 sitesthroughout the valley. Thanks to relatively continuous sedimentary records, a chronology of different lithic techno-complexes has been established. Acheulean industries date back to at least 90 ka while the bifacial-shaped pieces that typically characterize the Middle Stone Age can be dated to MIS3. Meanwhile, Late Stone Age industries (microlithic and geometric microlithic) are dated circa 15 to 10 ka. The need to document the chronology of prehistoric cultures has led us to carry out some methodological developments. To properly assess the micro-dosimetry of our samples, we used several techniques suh as an imaging system (ᵦ autoradiography) and a numerical simulation (DosiVox-2D). These methodological developments have inter alia shown that classical models tend to bias the dose rate and thus the dates. On the basis of our work, the Falémé Valley is therefore presented as the new sequence of reference for West African Prehistory,alongside the work that has been done in the Ounjougou complex in Mali.

This thesis is a study of the morphology and sediment transport dynamics of mountain streams in southeast Australia. Mountain streams represent important geomorphological and ecological systems in Australia which have hitherto been poorly studied. The variability of mountain stream reach morphology was investigated at the regional scale using topographical surveys and sediment sampling techniques. Study sites were stratified by slope and local lithology. Eight channel-morphologies including Bedrock, Cascade, Step-pool, Planebed, Pool-Riffle, Cascade-pool, Riffle-step and Infilled, were identified using an objective statistical approach. Overall, channel types were found to correspond to existing reach-scale mountain stream templates. Five morphologies were associated with a specific lithology type which controlled the size and shape of grains supplied to the channels. Differences in coarse sediment transport processes between morphologies were investigated using stream monitoring techniques and Optically Stimulated Luminescence (OSL) dating. Monitoring results from a 3 year period indicated that channel beds are resistant to entrainment with shear stress thresholds for bedload transport ranging between 64 to 74 N/m2. Transport of reach median grain sizes requires floods that exceed bankfull discharge. Existing competence equations were found to over-predict the hydraulic driving force and consequently, a modified entrainment model was used to account for the regional channel characteristics. OSL dating was investigated as a tool to provide data on long-term sediment transport processes. Minimum age model results from the OSL dates show overall agreement with a selected entrainment model, and indicate differences in sediment transport dynamics between some reach morphology types. A regime model was used to quantify the physical domains of different channel morphologies. Limitations of the model were overcome by modifying the sediment supply surrogate to better reflect the dominant transported bedload size. Morphology types were delineated according to different sediment transport capacity-sediment supply domains. The distribution of channel morphology types within a series of catchments in southeast Australia was modelled within a GIS platform using the diagnostics of reach morphology derived from this study. The model provides a conceptual framework to evaluate the potential link between channel form, potential habitat diversity and aquatic biodiversity within the channel network in mountain streams.

Charwell Basin is a 6 km-wide structural depression situated at the boundary between the axial ranges and faulted and folded Marlborough Fault Zone of north-eastern South Island, New Zealand. The basin contains the piedmont reach of the Charwell River, and a series of late Quaternary loess-mantled alluvial terraces and terrace remnants that have been uplifted and translocated from their sediment source due to strike-slip motion along the Hope Fault which bounds the basin to its immediate north. The aim of this study was to provide an interdisciplinary, integrated and holistic analysis of late Quaternary landscape evolution and environmental change in Charwell Basin using terrain analysis, loess stratigraphy, soil chemistry and paleoecological data. The study contributes new understanding of New Zealand landscape and ecosystem responses to regional and global climatic change extending to Marine Isotope Stage (MIS) 6, and shows that climatically-forced shifts in biogeomorphic processes play a significant role in lowland landscape evolution. Morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time, with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo-concave land elements. Paleotopographic analysis of a >150 ka terrace mantled by up to three loess sheets revealed multiple episodes of alluvial aggradation and degradation and, subsequent to river abandonment, gully incision prior to and coeval with loess accumulation. Spatial heterogeneity in loess sheet preservation showed a complex history of loess accumulation and erosion. A critical profile curvature range of -0.005 to -0.014 (d²z/dx², m⁻¹) for loess erosion derived from a model parameterised in different ways successfully predicted loess occurrence on adjacent slope elements, but incorrectly predicted loess occurrence on an older terrace remnant from which all loess has been eroded. Future analyses incorporating planform curvature, regolith erosivity and other landform parameters may improve identification of thresholds controlling loess occurrence in Charwell Basin and in other South Island landscapes. A loess chronostratigraphic framework was developed for, and pedogenic phases identified in, the three loess sheets mantling the >150 ka terrace. Except for one age, infrared-stimulated luminescence dates from both an upbuilding interfluve loess exposure and colluvial gully infill underestimated loess age with respect to the widespread Kawakawa/Oruanui Tephra (KOT; 27,097 ± 957 cal. yr BP), highlighting the need for improvements in the methodology. Onset of loess sheet 1 accumulation started at ca. 50 ka, with a break at ca. 27 ka corresponding to the extended Last Glacial Maximum (eLGM) interstadial identified elsewhere in New Zealand. Loess accumulation through MIS 3 indicates a regional loess flux, and that glaciation was not a necessary condition for loess generation in South Island. Loess accumulation and local alluvial aggradation are decoupled: the youngest aggradation event only covers ~12 kyr of the period of loess sheet 1 accumulation. Older local aggradation episodes could not be the source because their associated terraces are mantled by loess sheet 1. In the absence of numerical ages, the timing of L2 and L3 accumulation is inferred on the basis of an offshore clastic sediment record. The upbuilding phase of loess sheet 2 occurred in late MIS 5a/MIS 4, and loess sheet 3 accumulated in two phases in MIS 5b and late MIS 6. Biogenic silica data were used to reconstruct broad shifts in vegetation and changes in gully soil saturation status. During interglacial/interstadial periods (MIS 1, early MIS 3, MIS 5) Nothofagus-dominated forest covered the area in association with Microlaena spp grasses. Lowering of treeline altitude during glacial/stadial periods (MIS 2, MIS 3, MIS 5b, late MIS 6) led to reduction in forest cover and a mosaic of shrubs and Chionochloa spp, Festuca spp and Poa spp tussock grasses. Comparison of interfluve and gully records showed spatial heterogeneity in vegetation cover possibly related to environmental gradients of exposure or soil moisture. A post-KOT peak in gully tree phytoliths corresponds to the eLGM interstadial, and a shift to grass-dominated vegetation occurred during the LGM sensu stricto. Diatoms indicated the site became considerably wetter from ca. 36 ka, with peak wetness at ca. 30, 25 and 21 ka, possibly due to reduced evapotranspiration and/or increased precipitation from a combination of strengthened westerly winds and increased cloudiness, or strengthened southerly flow and increased precipitation. Human influence after ca. 750 yr BP led to re-establishment of grassland in the area, which deposited phytoliths mixed to 30 cm depth in the soil. A coupled gully colluvial infilling/vegetation record showed that sediment flux during the late Pleistocene was ~0.0019 m³ m⁻¹ yr⁻¹ under a shrubland/grassland mosaic, and Holocene sediment flux was ~0.0034 m³ m⁻¹ yr⁻¹ under forest. This increase of 60% through the last glacial-interglacial transition resulted from increased bioturbation and down-slope soil transport via root growth and treethrow, which formed a biomantle as evidenced by slope redistribution of the KOT. These results contrast with sediment transport rates and processes hypothesised to occur contemporaneously in adjacent mountain catchments. This suggests that intraregional biogeomorphic processes can differ significantly depending on topography and geological substrate, with different landscapes responding in unique ways to the same climate shifts. Analysis of Quaternary terrestrial landscape evolution in non-glaciated mountainous and lowland areas must therefore consider spatial and temporal heterogeneity in sediment fluxes and underlying transport processes.