The largest wildfire ever observed in Greenland raged through its tundra during august 2017, and it is unknown if there have been similar wildfires in the area before satellite monitoring began in 1999. Arctic wildfires affect permafrost degradation, carbon storage of soils and the surface albedo of the Greenland Ice sheet – despite this, local fires have previously been ignored by researchers. Here, aeolian dust deposits are independently dated by radiocarbon and luminescence techniques and paleoenvironmental proxies and macrocharcoal contents reflecting local fires are analyzed. The dating results indicate that the onset of aeolian deposition coincides with the deglaciation of the area, suggesting that paleoenvironmental proxy records from aeolian dust deposits may extend the entire ice-free period of the area until approximately 8 ka BP. Luminescence signals are generally partially bleached, resulting in age over-estimation of several samples. This effect is quantified using the pIRIR/IR ratio and different integration limit intervals. No evidence for previous wildfires were found during the charcoal analysis, suggesting that the area around the assessed profile has never been burnt since its deglaciation. These first results show promise for the method, and in order to expand this to a regional estimate of the wildfire activity through the Holocene, analysis of more material is needed.

This thesis presents stratigraphic, sedimentological and geochronological results from valley fill and glacial moraines of the Hope-Waiau Valleys in North Canterbury, New Zealand. The findings demonstrate that a substantial portion of the modern valley fill comprises in-situ sedimentary sequences that were deposited during the penultimate glaciation (OIS 6), the last interglacial (OIS 5) and during the mid-late last glacial cycle (OIS 3/2). The sediments survived at low elevations in the valley floor despite overriding by later glacial advances. Sedimentologically, the fill indicates deposition in an ice marginal zone and consists of paraglacial/distal-proglacial aggradation gravels and ice-proximal/marginal-subglacial sediments. Deposition during glacial advance phases was characterized by the sedimentation of outwash gravels and small push moraines while glacial retreat phases are dominated by glaciolacustrine deposits which are frequently interbedded with debris flow diamictons. The overall depositional arrangement indicates that glacial retreat from the lower valley portion occurred via large scale ice stagnation. Results from infra-red stimulated luminescence (IRSL) dating gives evidence for five large aggradation and degradation phases in the Hope-Waiau Valleys over the last 200 ka. Combined with surface exposure dating (SED) of moraines the geochronological results indicate that glacial advances during OIS 6 were substantially larger in both ice extent and ice volume than during OIS 4-2. The last glacial maximum (LGM) ice advance occurred prior to 20.5 ka and glacial retreat from extended ice positions began by ~18 ka BP. A late glacial re-advance (Lewis Pass advance) occurred at ~13 ka BP and is probably associated with a regional cooling event correlated to the Antarctic Cold Reversal (ACR). The findings from the Hope-Waiau Valleys were integrated into a model for glaciations in the Southern Alps which uses data from a snow mass balance model to analyse the sensitivity of glacial accumulation to temperature forcing. Model results indicate that in the central hyperhumid sector of the Southern Alps ice would expand rapidly with minor cooling (2-4℃) suggesting that full glaciation could be generated with little thermal forcing. Some Quaternary glacial advances in the Southern Alps may have been triggered by regional climate phenomena (e.g. changes in ENSO mode) rather than requiring a thermal trigger from the Northern Hemisphere.

Outcrops of late Quaternary deposits along the north–east coast of Mallorca were examined, and a high resolution chronological framework established using optically stimulated luminescence of quartz and feldspar grains. Coastal sections at Es Barrancar and Cala Mata record a complex succession of alluvial fan deposition with a minor aeolian component, mainly deposited during the last two glacial cycles. For the last ~200ka different orbital configurations appear to have produced a series of subtly different climatic scenarios that resulted in great variations in the regional availability of moisture. In turn, each of these climatic scenarios set in motion a distinct set of sedimentary processes, which imprinted themselves upon the character of fluvial system response recorded in the alluvial archives on Mallorca. Within the resulting complex of sediments were units of fluvially reworked aeolianite which, although truncated in places, were traceable laterally along wide sections of the sea front outcrops of both fan systems. These archives yielded 47 new OSL and pIRIR290 ages which suggest a number of previously unrecognised periods of enhanced fluvial activity. Luminescence ages identify significant ephemeral fluvial activity taking place during MIS 6, MIS 5 sub-stages d/c, b/a, and across the MIS 5/4 boundary. Another major phase of reworking corresponds with the middle part of MIS 3, and continued sporadically into the Last Glacial Maximum. These fluvial reworking events have been interpreted as having taken place during cold arid climatic intervals, when vegetation was at a minimum, precipitation was low and displayed a much higher degree of seasonality, enhancing the effects of runoff.

Recent work suggests an emerging new paradigm for the Scandinavian ice sheet (SIS); one of a dynamically fluctuating ice sheet. This doctoral research project explicitly examines the history and dynamics of the SIS at four sites within Sweden and Norway, and provides results covering different time periods of glacial history. Two relatively new dating techniques are used to constrain the ice sheet history: the optically stimulated luminescence (OSL) dating technique and the terrestrial cosmogenic nuclide (TCN) exposure dating technique. OSL dating of interstadial sediments in central Sweden and central Norway indicate ice-free conditions during times when it was previously inferred the sites were occupied by the SIS. Specifically, the SIS was absent or restricted to the mountains for at least part of Marine Isotope Stage 3 around 52 to 36 kyr ago. Inland portions of Norway were ice-free during part of the Last Glacial Maximum around 25 to 20 kyr ago. Consistent TCN exposure ages of boulders from the Vimmerby moraine in southern Sweden, and their compatibility with previous estimates for the timing of deglaciation based on radiocarbon dating and varve chronology, indicate that the southern margin of the SIS was at the Vimmerby moraine ~14 kyr ago. In central Sweden, consistent TCN ages for boulders on the summit of Mt. Åreskutan and for the earlier deglaciated highest elevation moraine related to the SIS in Sweden agree with previous estimates for the timing of deglaciation around 10 ka ago. These results indicate rapid decay of the SIS during deglaciation. Unusually old radiocarbon ages of tree remains previously studied from Mt. Åreskutan are rejected on the basis of incompatibility with consistent TCN ages for deglaciation, and incompatibility with established paleoecological and paleoglaciological reconstructions. Altogether this research conducted in different areas, covering different time periods, and using comparative geochronological methods demonstrates that the SIS was highly dynamic and sensitive to environmental change. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.

This thesis presents stratigraphic, sedimentological and geochronological results from valley fill and glacial moraines of the Hope-Waiau Valleys in North Canterbury, New Zealand. The findings demonstrate that a substantial portion of the modern valley fill comprises in-situ sedimentary sequences that were deposited during the penultimate glaciation (OIS 6), the last interglacial (OIS 5) and during the mid-late last glacial cycle (OIS 3/2). The sediments survived at low elevations in the valley floor despite overriding by later glacial advances. Sedimentologically, the fill indicates deposition in an ice marginal zone and consists of paraglacial/distal-proglacial aggradation gravels and ice-proximal/marginal-subglacial sediments. Deposition during glacial advance phases was characterized by the sedimentation of outwash gravels and small push moraines while glacial retreat phases are dominated by glaciolacustrine deposits which are frequently interbedded with debris flow diamictons. The overall depositional arrangement indicates that glacial retreat from the lower valley portion occurred via large scale ice stagnation. Results from infra-red stimulated luminescence (IRSL) dating gives evidence for five large aggradation and degradation phases in the Hope-Waiau Valleys over the last 200 ka. Combined with surface exposure dating (SED) of moraines the geochronological results indicate that glacial advances during OIS 6 were substantially larger in both ice extent and ice volume than during OIS 4-2. The last glacial maximum (LGM) ice advance occurred prior to 20.5 ka and glacial retreat from extended ice positions began by ~18 ka BP. A late glacial re-advance (Lewis Pass advance) occurred at ~13 ka BP and is probably associated with a regional cooling event correlated to the Antarctic Cold Reversal (ACR). The findings from the Hope-Waiau Valleys were integrated into a model for glaciations in the Southern Alps which uses data from a snow mass balance model to analyse the sensitivity of glacial accumulation to temperature forcing. Model results indicate that in the central hyperhumid sector of the Southern Alps ice would expand rapidly with minor cooling (2-4℃) suggesting that full glaciation could be generated with little thermal forcing. Some Quaternary glacial advances in the Southern Alps may have been triggered by regional climate phenomena (e.g. changes in ENSO mode) rather than requiring a thermal trigger from the Northern Hemisphere.

High resolution dating of loess on the Chinese Loess Plateau (CLP) using Optically Stimulated Luminescence (OSL) has increased the understanding of past monsoon climate but also raised questions regarding dust mass accumulation rate (MAR), the presence of disturbances or gaps in the sediment record, a possible teleconnection between North Atlantic and East Asian monsoon climate, and whether these events are due to climate variability, local settings, or age model uncertainties. This study undertakes a detailed (<20cm sampling resolution) -OSL investigation of the Lingtai section to create an independent age model using linear regression, to reconstruct monsoon climate changes using magnetic susceptibility(MS) and grain size (GS) proxies, as well as to calculate MAR for the site. The data shows that between 44-15 ka climate changes from a period of strong summer monsoon to a strong winter monsoon. GS data show variable trends attributed to changes in dust storm activity and local environmental conditions. MAR data does not correlate with grain size and is different from other loess records on the CLP. Such differences are either due to local variations or age model uncertainties. No clear correlation with Heinrich events or teleconnection with North Atlantic climate is visible in the records over the Last Glacial period, and hiatuses or gaps are not obviously present at this site. It is suggested that using linear regression for continuous age model construction from the luminescence ages comes with uncertainties due to subjective bias when fitting the lines and determining shifts in the data, especially during MAR calculations. Further studies are needed to ascertain optimal methods for creating age models, and to constrain the reasons behind the variability between different sites and loess records on the CLP. / Högupplöst OSL-datering av loessjordar från CLP har ökat förståelsen av dåtida monsunklimat, men har även lyft frågan gällande MAR, närvaron av avbrott eller småskaliga event i jordsektionerna, möjligheten av en relation mellan de Nordatlantiska och Ostasiatiska monsunklimaten, och om dessa förändringar sker till följd av faktisk klimatvariation, lokala förutsättningar, eller osäkerheter i åldersmodellen. Studien genomförde en detaljerad (<20cm) OSL-undersökning av Lingtai-sektionen för att skapa en oberoende åldersmodell, återge monsunklimatförändringarna genom tillämpning av MS och GS proxies, samt beräkna MAR från platsen. Resultaten påvisar att mellan 44-15 ka förändrades klimatet från en period av stark sommar- till en stark vinter-monsun. Kornstorleks-resultaten påvisar stora variationer vilka kan kopplas till en förändring i sandstormsaktivitet samt de lokala förutsättningarna för deposition av sediment. MAR-resultaten överensstämmer inte med kornstorleksdatan och skiljer sig från den övriga empirin, detta kan bero på lokala variationer i regionen eller osäkerheter i åldermodellen. Det finns ingen klar korrelation mellan "Heinrich events" eller en "teleconnection" i sektionen, och avbrott samt störningar i sektionen är inte förekommande. Avsaknaden av korrelation antyder att användningen av regressionslinjer för att skapa kontinuerliga åldermodeller kommer innebära fortsatta osäkerheter i empirin, speciellt gällande beräking av MAR. Ytterligare studier krävs för att bestämma optimala metoder för att framställa åldersmodeller, samt att utröna orsaken till skillnaden mellan resultat från olika platser på plat

Accurate estimation of environmental dose rate is essential for high-resolution trapped-charge dating. Beta and gamma emissions from simulated sediments containing radioactive uranium, thorium and potassium are modelled in contexts that are spatially heterogeneous. Dose rate was modelled using Monte Carlo radiation transport codes MCNP and PENELOPE. A number of key issues that affect dose rate evaluation are examined and updated corrections are calculated. Granular structures used for geometrical input into the models were simulated using randomly packed ellipsoids. The pair correlation function and chord length distributions were derived. The effects of water content on dose rate were modelled and compared with cavity theory. Apart from activity dilution, the variation of grain size or water content was shown to be significant for gamma radiations due to the transition from charged particle equilibrium. The standard correction for beta dose rate due to grain size was found to be satisfactory although sensitivity to grain shape and material should be taken into account. Dose rate modeling was applied to three dating studies of early human fossils: Skhul V, Israel skull; Hofmeyr, South Africa skull and the Forbes’ Quarry, Gibraltar skull. The spatial modelling was implemented using computerised tomographic (CT) images and dose rate found to be modified significantly by the presence of the skull in the sediment. Time evolution of the dose rate was examined for the latter two skulls and dates of 36±3ka (Hofmeyr) and 55-95ka (Forbes’ Quarry) were calculated.

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.

This thesis takes a multidisciplinary approach to the study of ancient Egyptian ceramics by applying scientific dating techniques alongside more traditional methods. It is the first study to apply OSL dating to an Egyptian ceramic assemblage, and it has done so by developing the minimum extraction technique (MET), which has made it possible to use OSL to sample, and thus analyse, ceramics housed in museums. The MET is at present essential to the success of OSL dating of Egyptian ceramics, as the exportation ban on antiquities has prevented OSL analysis of field material. For this thesis, using this new sampling technique, OSL has been applied to several assemblages from the Predynastic to the Early Dynastic period. Ceramics from [ADD IN REVIEW ] have been examined, with three phases being established: late Naqada III, First Intermediate Period, and the mediaeval Islamic period. Absolute dates have been determined for each phase and, where comparison is possible, have been found in good agreement with the historical chronology. A set of vessels from Naqada, Ballas, and the Tomb of Djer at Abydos have been examined using OSL in conjunction with radiocarbon dating. Again, three phases of activity were discerned: late Naqada II, early Naqada III, and the first scientifically determined dates for a burning event in the Tomb of Djer (the New Kingdom). The thesis also demonstrates how OSL can be used as a relative dating technique by analysing a collection of Wavy-Handled ceramics and wine jars from Turah, finding that the OSL results agree well with the established relative chronology. Finally, this thesis has also examined the applicability of cladistic analysis to the study of Egyptian ceramics. Cladistics is a technique borrowed from the biological sciences which offers a complimentary way to examine the evolution of ceramic types and forms, in particular the development of beer and wine jars.

The optically stimulated luminescence (OSL) characteristics of a suite of quartz and feldspar samples from a range of modern glaciofluvial sediments have been explored to determine the use of OSL as a depositional pathway tracer. Paraglacial and subglacial source material and various glaciofluvial deposits have been analysed from the glacial catchments of Bergsetbreen, Fåbergstølsbreen, and Nigardsbreen as well as the Fåbergstølsgrandane sandur, Jostedalen, Norway. The OSL distribution signatures have been characterised through exploration of sample skewness, kurtosis and overdispersion, and dose distributions of the different depositional settings and source materials are distinct for both quartz and feldspar. Residual ages are greatest for feldspar, indicating significant potential age overestimation where feldspar is used to date glaciofluvial deposits. Sample dose distributions and overdispersion characteristics are driven by source sediment properties, whereas residual ages are controlled by transport and depositional processes. Those transport and depositional processes which result in significant light exposure, also influence dose distributions, and processes that sort sediments least effectively have the highest residual doses. Sample OSL characteristics, transport distance and grain size distributions have been investigated using factor analysis, as a means of predicting sediment source, facies, depositional process and deposit type. Although the depositional processes of the quartz samples can be clearly differentiated based upon OSL characteristics, factor analyses of feldspar and grain size characteristics are inconclusive. The application of quartz OSL to the Norwegian samples was limited by its very poor luminescence sensitivity. Quartz is the preferred mineral for OSL, however, despite the plethora of successful quartz OSL applications, the precise origin of the UV/blue luminescence emission, measured during OSL, remains unclear. The origins of this emission and controls on its intensity were explored using a variety of spectroscopic techniques including photoluminescence, cathodoluminescence, radioluminescence (RL), ionoluminescence (IL) and x-ray excited optical luminescence (XEOL). Exciting sample luminescence at a range of energies enables exploration of the different donor centres responsible for the luminescence emission. Cathodoluminescence and RL emission spectra are similar, comprising broad emissions at 1.5, 2.0 and 2.7 eV (detection in the UV part of the spectrum was not possible for these experiments). Ionoluminescence emission spectra were dominated by the ~ 3.3 eV emission, which is a component of the signal conventionally monitored during OSL. This emission depleted as a function of dose, to the benefit of the red emission (1.8-2.0 eV) for all samples throughout IL, and similar observations were made for the 3.4 eV emission observed from the XEOL emission spectra. The XEOL spectra are dominated by an emission at ~ 3.8 eV, not widely reported for quartz, which has tentatively been attributed to peroxy linkages. Differences between the IL and XEOL emission spectra are interpreted as evidence for the presence of multiple excited states.