Loess from west Greenland was studied to evaluate Holocene paleoclimate in the Arctic region. Deposits of loess are formed over long time scales through deposition of fine aeolian sediment and they exist in several places in the world. The main aeolian dust source in the study area is glaciofluvial material derived from the Greenland Ice Sheet (GrIS). Studying and understanding paleoclimate can help to make better predictions about the future in this sensitive region. Apart from sea level rise, melting of the GrIS also leads to an increase of aeolian dust as it gets released from the ice, which influences atmospheric and metrological phenomenon as well as the ice sheet’s albedo. This creates negative feedback mechanisms through increasing melting rates of glaciers and warming of the Arctic. Loess samples from two sites in the Kangerlussuaq area were analyzed and the mineral composition was measured with X-Ray Florescence Spectroscopy (XRF). With the measured mineral content, weathering indices were calculated to identify rates of weathering during the Holocene. Increased weathering intensities indicate warmer and more humid climate. The deposits in Greenland are relatively thin. Radiocarbon dating of the sediment suggests that the oldest parts of the profiles are about 4000 cal. yr B.P. (calibrated years before present). Arctic loess has not been studied very extensively. Weathering indices and ratios developed for classical loess, that had not been tested on Arctic loess, was used. The results were plotted by depth and age to visually identify changes over time. By considering the geology, climate and local conditions of the study area, some weathering indices seemed to be suitable, generating matching trends between the two sites. Compared with results from previous studies, the results also seemed credible. / Löss från västra Grönland studerades för att utvärdera holocent paleoklimat i Arktis. Lössjordar bildas över långa tidsskalor genom avsättning av fint vindburet sediment och de finns på flera platser i världen. Den huvudsakliga källan till det vindburna sedimentet i studieområdet är glaciofluvialt material härstammande från Grönlandsisen (GrIS). Att studera och förstå paleoklimat kan underlätta skapandet av bättre prognoser om framtiden i denna känsliga region. Bortsett från höjning av de globala havsnivåerna leder smältningen av GrIS också till en ökning av vindburet sediment då det frigörs från isen, vilket påverkar atmosfäriska och metrologiska fenomen samt isens albedo. Detta skapar negativa återkopplingsmekanismer genom ökande smälthastighet av glaciärer och uppvärmning av Arktis. Lössprover från två ställen i Kangerlussuaq-området analyserades och mineralsammansättningen mättes med röntgenstrålningsspektroskopi (XRF). Med det uppmätta mineralinnehållet beräknades vittringssindex för att identifiera vittringshastigheter under Holocen. Ökad vittringsintesitet indikerar varmare och fuktigare klimat. Avlagringarna på Grönland är relativt tunna. Kol-14-datering av sedimentet antyder att de äldsta delarna är cirka 4000 cal. yr B.P. (kalibrerade år före nutid). Arktisk löss är relativt ostuderad. Vittringsindex som har utvecklats för klassisk löss i tempererade regioner, och tidigare inte testats på arktisk löss, användes. Resultaten ritades i grafer efter djup och ålder för att visuellt identifiera förändringar över tid. Genom att ta hänsyn till geologin, klimatet och lokala förhållanden i studieområdet, verkade några av vittringsindexen ge trovärdiga resultat då matchande trender mellan bägge profiler kunde utläsas. I jämförelse med resultat från tidigare studier verkade resultaten också trovärdiga.

The purpose of this research was to investigate the physical weathering of rock along the Victoria Land Coast, Antarctica. It was designed to contribute to the Latitudinal Gradient Project, a joint initiative between the New Zealand, Italian and United States Antarctic Programmes. The Latitudinal Gradient Project aims to improve our understanding of the ecosystems of the Dry Valleys and ice-free areas of the Ross Sea Region and, by using latitude as a proxy measure, identify how they might be affected by future climate change. The approach taken for this research was to use information on rock (from one rock group) temperature and moisture conditions gathered from three field locations to inform laboratory simulations. The laboratory simulations would then be used to investigate the weathering of small rock blocks and aggregates. Two temperature cycles approximating those experienced during summer and spring/autumn were identified and simulations undertaken in a specially adapted freezer. Three levels of moisture were applied: no moisture, half saturation and full saturation. Results of the laboratory simulations indicated that although rocks responded in different ways to different processes, granular disintegration took place even in the absence of additional moisture and did not require crossings of the 0 OC isotherm, nor were high levels of moisture required for across zero temperature cycling to produce weathering effects. A model that related weathering to latitude was developed and changes in climate explored. It was found that the weathering effect of summer and spring/autumn cycles was different and depended on rock characteristics rather than latitude. Increasing the ratio of summer to spring/autumn temperature cycles by 10% indicated that weathering could decrease or remain the same depending on the particular rock. Changes in temperature were found to be more important than changes in moisture. A weathering index that related local climate and rock properties to weathering was also developed and this highlighted the difficulties of using laboratory results to predict field rates of weathering. There were some surprising results from the field, including the presence of much more moisture on the surface of the rock, primarily from blowing snow, than had been predicted for this dry environment. This occurred even in the presence of negative rock surface temperatures. In addition, winter rock surface temperatures can fluctuate up to 25 OC, getting as warm as -10 OC. Macro-climate and changes in air temperature in response to foehn and katabatic winds were the drivers for these fluctuations.

O saprolito é um corpo geológico constituído pela mistura de minerais primários e secundários resultantes do intemperismo físico e químico, o qual mantém vestígios da estrutura original da rocha. Difere do solo pela evidente filiação litogenética e insignificante atividade biológica. Apesar das definições, no entanto, o limite e a distinção entre solo e saprolito nem sempre são claros, devido a continuidade entre estes corpos em termos de processos hidrológicos e geoquímicos, bem como de suas composições físicas e mineralógicas, o que gera grande confusão nas descrições morfológicas e na organização de informações. Devido ao caráter multidisciplinar das ciências envolvidas no estudo do saprolito e a dedicação parcial de todas elas, há uma grande carência de padronização de termos e procedimentos para sua caracterização e análise. O objetivo geral desta tese é a caracterização de saprolitos desenvolvidos a partir de variadas litologias, no intuito da elaboração de procedimentos para a descrição, classificação e análise de saprolitos. Especificamente objetivou-se avaliar detalhadamente os padrões de alteração física, mineralógica e geoquímica em materiais, influenciados por atributos litológicos relativos a composição mineralo-química e estrutural do material parental. Para tanto foram descritos e amostrados 15 perfis de alteração; compostos por solo, saprolito e rocha, derivados de rochas sedimentares e metamórficas na região Sudeste do Brasil, nos estados de São Paulo e Minas Gerais. As descrições demonstraram que os corpos saprolíticos avaliados podem ser agrupados em quatro tipos morfológicos principais, sendo propostas as seguintes categorias estruturais: contínua, fraturada, fragmentada e terrosa. Dentre todos saprolitos avaliados, aqueles derivados de rochas metamórficas apresentaram maior complexidade morfológica. Deste modo, 9 perfis filiados a xistos e gnaisses foram submetidos a análises físicas, geoquímicas e mineralógicas para avaliação dos processos de alteração e desenvolvimento de sistema de classificação. A composição mineralógica de solos e saprolitos se mostrou semelhante, entretanto, ocorreram dissimilaridades geoquímicas entre estes corpos. Atributos físicos como densidade e porosidade total não demonstraram diferenças significativas entre solo e saprolito, entretanto, ao se considerar isoladamente amostras de saprolito, houve correlação positiva entre a perda de massa e a porosidade total, tornando este último atributo útil `a proposta de classificação de saprolitos. / The saprolite is a geological body constituted by the mixture of primary and secondary minerals resulting of physical and chemical weathering, which retains traces of the original rock structure. It differs from the soil by the evident litogenetic affiliation and insignificant biological activity. Although the definitions, however, the limit and the distinction between soil and saprolite are not always clear, because the continuity between these bodies in terms of hydrological and geochemical processes, as well as their physical and mineralogical compositions, which creates great confusion in morphological descriptions and information network. Due to the multidisciplinary nature of the sciences involved and the partial dedication of all of them in the saprolite investigations, there is a great lack of standardization of terms and procedures for characterization and analysis. The overall objective of this thesis is the characterization of saprolite developed from various lithologies in order to draw up procedures for the description, classification and saprolite analysis. Specifically aimed to evaluate in detail the patterns of physical, mineralogical and geochemical changes in some materials influenced by lithological attributes how the mineralogical and chemical composition, as well as the structure of parental material. For this were described and sampled 15 weathering profiles, composed of soil, saprolite and rock derived from sedimentary and metamorphic rocks in southeastern Brazil, in the states of São Paulo and Minas Gerais. The descriptions shown that saprolite evaluated can be grouped into four main morphological types, proposed the following structural categories: continuous, fractured, fragmented and earthy. Among all evaluated saprolite, those derived from metamorphic rocks showed higher morphological complexity. Thus, 9 affiliated profiles schists and gneisses to have been subjected to physical, geochemical and mineralogical analyzes to evaluate the change processes and to developing the classification system of saprolites. The mineralogical composition of soils and saprolite was similar, however, there were dissimilarities regard geochemical attributes between this bodies. Physical properties such as density and porosity showed no significant differences between soil and saprolite, however, when considered in isolation saprolite samples, there was a positive correlation between weight loss and total porosity, making this last attribute able to integrate the proposed saprolite classification.

O saprolito é um corpo geológico constituído pela mistura de minerais primários e secundários resultantes do intemperismo físico e químico, o qual mantém vestígios da estrutura original da rocha. Difere do solo pela evidente filiação litogenética e insignificante atividade biológica. Apesar das definições, no entanto, o limite e a distinção entre solo e saprolito nem sempre são claros, devido a continuidade entre estes corpos em termos de processos hidrológicos e geoquímicos, bem como de suas composições físicas e mineralógicas, o que gera grande confusão nas descrições morfológicas e na organização de informações. Devido ao caráter multidisciplinar das ciências envolvidas no estudo do saprolito e a dedicação parcial de todas elas, há uma grande carência de padronização de termos e procedimentos para sua caracterização e análise. O objetivo geral desta tese é a caracterização de saprolitos desenvolvidos a partir de variadas litologias, no intuito da elaboração de procedimentos para a descrição, classificação e análise de saprolitos. Especificamente objetivou-se avaliar detalhadamente os padrões de alteração física, mineralógica e geoquímica em materiais, influenciados por atributos litológicos relativos a composição mineralo-química e estrutural do material parental. Para tanto foram descritos e amostrados 15 perfis de alteração; compostos por solo, saprolito e rocha, derivados de rochas sedimentares e metamórficas na região Sudeste do Brasil, nos estados de São Paulo e Minas Gerais. As descrições demonstraram que os corpos saprolíticos avaliados podem ser agrupados em quatro tipos morfológicos principais, sendo propostas as seguintes categorias estruturais: contínua, fraturada, fragmentada e terrosa. Dentre todos saprolitos avaliados, aqueles derivados de rochas metamórficas apresentaram maior complexidade morfológica. Deste modo, 9 perfis filiados a xistos e gnaisses foram submetidos a análises físicas, geoquímicas e mineralógicas para avaliação dos processos de alteração e desenvolvimento de sistema de classificação. A composição mineralógica de solos e saprolitos se mostrou semelhante, entretanto, ocorreram dissimilaridades geoquímicas entre estes corpos. Atributos físicos como densidade e porosidade total não demonstraram diferenças significativas entre solo e saprolito, entretanto, ao se considerar isoladamente amostras de saprolito, houve correlação positiva entre a perda de massa e a porosidade total, tornando este último atributo útil `a proposta de classificação de saprolitos. / The saprolite is a geological body constituted by the mixture of primary and secondary minerals resulting of physical and chemical weathering, which retains traces of the original rock structure. It differs from the soil by the evident litogenetic affiliation and insignificant biological activity. Although the definitions, however, the limit and the distinction between soil and saprolite are not always clear, because the continuity between these bodies in terms of hydrological and geochemical processes, as well as their physical and mineralogical compositions, which creates great confusion in morphological descriptions and information network. Due to the multidisciplinary nature of the sciences involved and the partial dedication of all of them in the saprolite investigations, there is a great lack of standardization of terms and procedures for characterization and analysis. The overall objective of this thesis is the characterization of saprolite developed from various lithologies in order to draw up procedures for the description, classification and saprolite analysis. Specifically aimed to evaluate in detail the patterns of physical, mineralogical and geochemical changes in some materials influenced by lithological attributes how the mineralogical and chemical composition, as well as the structure of parental material. For this were described and sampled 15 weathering profiles, composed of soil, saprolite and rock derived from sedimentary and metamorphic rocks in southeastern Brazil, in the states of São Paulo and Minas Gerais. The descriptions shown that saprolite evaluated can be grouped into four main morphological types, proposed the following structural categories: continuous, fractured, fragmented and earthy. Among all evaluated saprolite, those derived from metamorphic rocks showed higher morphological complexity. Thus, 9 affiliated profiles schists and gneisses to have been subjected to physical, geochemical and mineralogical analyzes to evaluate the change processes and to developing the classification system of saprolites. The mineralogical composition of soils and saprolite was similar, however, there were dissimilarities regard geochemical attributes between this bodies. Physical properties such as density and porosity showed no significant differences between soil and saprolite, however, when considered in isolation saprolite samples, there was a positive correlation between weight loss and total porosity, making this last attribute able to integrate the proposed saprolite classification.

The purpose of this research was to investigate the physical weathering of rock along the Victoria Land Coast, Antarctica. It was designed to contribute to the Latitudinal Gradient Project, a joint initiative between the New Zealand, Italian and United States Antarctic Programmes. The Latitudinal Gradient Project aims to improve our understanding of the ecosystems of the Dry Valleys and ice-free areas of the Ross Sea Region and, by using latitude as a proxy measure, identify how they might be affected by future climate change. The approach taken for this research was to use information on rock (from one rock group) temperature and moisture conditions gathered from three field locations to inform laboratory simulations. The laboratory simulations would then be used to investigate the weathering of small rock blocks and aggregates. Two temperature cycles approximating those experienced during summer and spring/autumn were identified and simulations undertaken in a specially adapted freezer. Three levels of moisture were applied: no moisture, half saturation and full saturation. Results of the laboratory simulations indicated that although rocks responded in different ways to different processes, granular disintegration took place even in the absence of additional moisture and did not require crossings of the 0 OC isotherm, nor were high levels of moisture required for across zero temperature cycling to produce weathering effects. A model that related weathering to latitude was developed and changes in climate explored. It was found that the weathering effect of summer and spring/autumn cycles was different and depended on rock characteristics rather than latitude. Increasing the ratio of summer to spring/autumn temperature cycles by 10% indicated that weathering could decrease or remain the same depending on the particular rock. Changes in temperature were found to be more important than changes in moisture. A weathering index that related local climate and rock properties to weathering was also developed and this highlighted the difficulties of using laboratory results to predict field rates of weathering. There were some surprising results from the field, including the presence of much more moisture on the surface of the rock, primarily from blowing snow, than had been predicted for this dry environment. This occurred even in the presence of negative rock surface temperatures. In addition, winter rock surface temperatures can fluctuate up to 25 OC, getting as warm as -10 OC. Macro-climate and changes in air temperature in response to foehn and katabatic winds were the drivers for these fluctuations.

Huge changes in climate occurred at the end of the last Quaternary glaciation. The end of this glaciation corresponds with the end of Pleistocene with its repeated glacial cycles and the start of the current geological epoch, the Holocene interglacial. The climate at this time was characterized by increasing temperatures and an increase in rainfall. This project focuses on understanding and examining these changes in climate using loess deposits from south-western England. Loess is an aeolian sediment and covers around 10 % of the Earth’s land surface and these deposits are excellent archives of past climate. Investigating loess can give understanding of past regional and local wind circulation patterns, atmospheric dustiness as well as weathering conditions. Studying paleoclimate is important since studying and understanding trends in past climate can increase our understanding of how the climate will change in the future. This study examined loess from two sites in south-western England, Porth Cressa and Lowland Point. These are relatively thin deposits; Lowland Point has a thickness of 180 cm and Porth Cressa has a thickness of 97 cm. England lacks the thick loess deposits that can be found in other parts of the world and thus the study of English loess has mostly been neglected. These deposits thus could contain unutilized information about paleoclimate. The elemental composition of the samples was examined using X-Ray Fluorescence (XRF). With the measured elemental composition, it’s possible to use weathering indices to see trends in postdepositional weathering. Low weathering intensities indicate a colder and drier climate, while higher weathering intensities indicate a warmer and more humid climate. The results from the weathering indices were plotted against depth at the two sites to identify changes in weathering and hence climate over time. Compared with the results from previous studies the results from some weathering indices seemed credible. Previous studies have indicated that the Chemical Proxy of Alteration (CPA) is the most appropriate weathering index for loess and the results from this study supports that theory. The results from the CPA show a trend with decreasing weathering intensities followed by a trend with increasing weathering intensities This implies that there was a period with decreasing temperatures/humidity followed by a period with increasing temperature humidity sometime at the end of the last glaciation. The geochemical data also showed support for a previous archaeological theory that there has been human reworking in the upper horizons at Lowland Point. / Slutet av den sista kvartära glaciationen var en tid med stora klimatförändringar. Denna tid sammanfaller med slutet av Pleistocene och dess glaciära cyklar samt starten på den nuvarande geologiska epoken, Holocen. Klimatet vid den här tiden karaktäriserades av ökande temperaturer och ökande nederbörd. Det här projektet fokuserar på att granska och förstå dessa klimatförändringar med hjälp av lössjordar från sydvästra England. Löss bildas av vindburet sediment och täcker ungefär 10 % av jordens landyta, dessa avlagringar är utmärkta arkiv för historiskt klimat. Att undersöka lössjordar kan ge information om historiska regionala och lokala vindcirkulations-mönster, vittringsförhållanden samt mängden damm i atmosfären. Att undersöka paleoklimat är viktigt då förståelse för trender i tidigare klimat kan ge oss förståelse för hur klimatet kommer förändras i framtiden. Den här studien undersökte löss från två platser i sydvästra England, Lowland Point och Porth Cressa. Dessa avlagringar är relativt tunna; Lowland Point har en tjocklek på 180 cm och Porth Cressa har en tjocklek på 97 cm. England har inte de tjocka lössavlagringarna som går att hitta i andra delar av världen och därför har lite forskning utförts på brittiskt löss. Dessa avlagringar kan alltså innehålla oanvänd information om paleoklimat. Provernas grundämnessammansättning undersöktes med X-Ray Fluorescence (XRF). Med den uppmäta grundämnessammansättningen är det möjligt att använda vittringsindex för att se trender i vittring efter deposition. En låg vittringsintensitet indikerar ett kallare och torrare klimat medan en högre vittringsintensitet indikerar ett varmare och fuktigare klimat. Resultaten plottades mot djup för att visuellt identifiera förändringar i klimatet över tid. Vid jämförelse med tidigare studier verkade resultaten från vittringsindexen trovärdiga. Tidigare studier har föreslagit att CPA (Chemical Proxy of Alteration) är det mest lämpliga vittringsindexet för lössjordar och resultaten från denna studie stödjer den teorin. Resultaten från CPA visade på en trend med minskade vittringsintensitet följt av en trend med ökande vittrings intensitet. Detta antyder att det var en period med minskande temperatur/fuktighet följt av en period med ökande temperatur/fuktighet runt slutet av den senaste istiden. De geokemiska resultaten stödde också den tidigare arkeologiska teorin att mänsklig aktivitet har påverkat de övre horisonterna vid Lowland Point.