Several soil chronosequences were studied in southern California to determine the relative impacts of time and climatic change on soil genesis. Studying soil development in climatic regimes that vary from the moist, xeric climate of the coastal basins and Transverse Ranges to the hot, arid climate of the interior deserts of southern California provide data useful for evaluation of the impact of climatic change as well as time on pedogenesis. Seven distinctive stages of soil development are recognized in the study area. The first three occur in Holocene soils, and the last four are associated with late to mid-Pleistocene geomorphic surfaces. A distinct pattern of secondary soil mineral authigenesis is observed in increasingly older soils. The rapid formation of vermiculite and iron oxyhydroxides in xeric climates is attributed to rapid alteration of unstable Fe-bearing aluminosilicates. Continuous weathering of abundant feldspars results in a predominance of neogenetic kaolinite in mid-Pleistocene soils. Slightly acidic to mildly alkaline soil pH, rapid hydrolysis, and availablity of organic complexes result in formation of significant amounts of metastable ferrihydrite in young Holocene and late Pleistocene soils. Ferrihydrite dehydration and crystal aggregation result in hematite formation and increasingly lower Fe(,2)O(,3)o:Fe(,2)O(,3)d ratios. Arid climatic regimes are conductive to minimal chemical weathering. Clay/iron oxhydroxide regression analyses and mass balance calculations show that much of the silicate clay and secondary carbonate have been derived from external sources rather than by chemical weathering. Clay mineral authigenesis is characterized primarily by conversion of montmorillonite to palygorskite. A compartmental model developed in this study accurately predicts calcic horizon development under Holocene soil water balance characteristics. Results of model predictions indicate that the distribution of carbonate observed in latest Pleistocene soils is related to past changes in climate. In addition, mass balance calculations suggest that large decreases in chemical reaction rates in soils due to soil temperature decreases may well be offset by increases in the magnitude of weathering. However, the results of this study indicate that calcium carbonate provides the most sensitive index of past climates when compared to other indices and that temporal change in climate has significantly influenced soil development in southern California.

Orientador: Francisco Sergio Bernardes Ladeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-26T07:25:27Z (GMT). No. of bitstreams: 1 Alves_DiegoSullivandeJesus_M.pdf: 4590698 bytes, checksum: d732916e8700f1dfb1b644c57a1698cc (MD5) Previous issue date: 2014 / Resumo: A presente pesquisa tem como objetivo caracterizar os paleossolos da Formação Marília (Neocretáceo) no município de Campina Verde, região do Triângulo Mineiro, estado de Minas Gerais, e identificar as condições de formação durante a origem e desenvolvimento dos eventos pedogenéticos. A Formação Marília aflora em partes dos estados de São Paulo, Minas Gerais (região do Triângulo Mineiro), Mato Grosso do Sul e Goiás. É caracterizada por arenitos, conglomerados e argilitos/siltitos, com frequente ocorrência de calcretes e silcretes. Foi depositada sob uma associação de sistemas de leques aluviais de regimes torrenciais, fluviais e lacustres efêmeros, ou ainda, como um antigo sistema de lençóis de areia eólica. Foi realizado o reconhecimento dos paleossolos em três pontos distintos (Bastos 1, 2 e Capela), a partir das descrições macromorfológicas e análises laboratoriais (micromorfológicas, fluorescência de raios X, e difração por raios X). Conforme os resultados obtidos, dentificaram-se associações verticais entre paleossolos e depósitos sedimentares, os quais representam, respectivamente, períodos de estabilidade e instabilidade das superfícies. Em geral, ocorrem horizontes carbonáticos, comumente apresentando marcas de raízes e, pontualmente, associados à formação de calcretes e estruturas pedológicas, que evidenciam alto grau de desenvolvimento pedogenético. As estimativas de paleoprecipitação revelaram valores entre 308 mm/ano (horizonte calcretizado, Cca) e 1117 mm/ano (horizonte C/R). Constatou-se a predominância de palygorskita nos perfis de paleossolos, que é normalmente associada a ambientes secos e quentes, e especificamente no Bastos 1 (PP1), foi verificada presença de goethita, geralmente encontrada em solos altamente intemperizados, sob climas úmidos. Conclui-se que o clima semiárido prevaleceu durante a formação dos paleossolos e calcretes, com uma média de aproximadamente 530 mm anuais, marcado pela escassez, irregularidade e concentração das precipitações. O PP1 (Bastos 1) que registrou valores acima dos 1000 mm/ano sugerem condições de intenso intemperismo (CIA-K acima de 90), determinantes na remoção de bases por lixiviação, e que impediam a cimentação por carbonato de cálcio na matriz. Esses valores de paleoprecipitação não são decorrentes de fatores relativos à sazonalidade, mas estão associados a mudanças climáticas regionais, baseadas em ambientes com condições de maior umidade disponível / Abstract: This present research aims to characterize the paleosols of Marília Formation (Bauru Group) in Campina Verde, region of Triângulo Mineiro, in Minas Gerais, and identify the formation conditions during the origin and development of pedogenetic events. The Marília Formation outcrops in parts of the states of São Paulo, Minas Gerais (Triângulo Mineiro), Mato Grosso do Sul e Goiás. It¿s characterized by sandstones, conglomerates and mudstones/siltstones with frequent occurrence of calcretes and silcretes. It was deposited under an association of alluvial fans from torrential regimes, ephemeral fluvial and lacustrine systems, or even as an ancient system of aeolian sand sheet. Recognition of paleosols was carried out at three different points (Bastos 1, 2 and Capela), from macromorphological descriptions and laboratory analyzes (micromorphological, X-ray fluorescence and X-ray diffraction). Accordingly to the results, vertical associations were identified between paleosols and sedimentary deposits, which represent periods of stability and instability of surfaces, respectively. In general, carbonate horizons occurs, usually showing traces of roots and occasionally associated with formation of calcretes and pedological structures, which show a high degree of pedogenetic development. Estimates of paleoprecipitation revealed values between 308 mm/year (calcretized horizon, Cca) and 1117 mm/year (horizon C/R). It was verified a predominance of palygorskite in paleosol profiles, which is normally associated with hot and dry conditions, and, specifically in Bastos 1 (PP1), was observed the presence of goethite, usually found in highly weathered soils in humid climates. We concluded that the semi-arid climate prevailed during the formation of paleosols and calcretes, with an average of about 530 mm annual, marked by scarcity, irregularities and concentrations of precipitations. The PP1 (Bastos 1) which recorded values above 1000 mm/year suggest intense weathering conditions (CIA-K above 90) which are determinant bases removal by leaching and preventing the calcium carbonate cementation in the matrix. These paleoprecipitation values are not due to factors related to seasonality, but are associated with regional climate change based in environment with conditions of higher moisture available / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

Orientador: Francisco Sérgio Bernardes Ladeira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-20T22:32:57Z (GMT). No. of bitstreams: 1 Bueno_RobertaMarquezi_M.pdf: 8038871 bytes, checksum: d7a9deb149b8074a8cb315a27706bd4a (MD5) Previous issue date: 2012 / Resumo: O Grupo Urucuia, localizado na porção centro-norte da Bacia Sanfraciscana, abrange os estados do Piauí, Bahia, Maranhão, Goiás, Tocantins e Minas Gerais e é formado por um conjunto de arenitos continentais datados do Cretáceo Superior e depositado sobre embasamento fanerozóico e sobre os Grupos Santa Fé e Areado, ambos também pertencentes à Bacia Sanfranciscana. O Grupo Urucuia é composto pelas Formações Posse e Formação Serra das Araras. A Formação Posse é caracterizada pelo deposito de material arenoso em campos de dunas e fluvial entrelaçado, já a Formação Serra das Araras foi depositada sobre a Formação Posse sendo caracterizada por lençóis de areia e depósito de clastos. Uma vez que a área em que está o Grupo Urucuia permaneceu praticamente na mesma latitude desde a separação de Gondwana, seus registros paleoclimáticos dizem respeito a mudanças climáticas em uma mesma latitude. Os depósitos indicam uma situação desértica que vai se tornando cada vez mais úmida. As mudanças ambientais da área também ficaram registradas nos paleossolos do Grupo Urucuia. Eles foram descritos em um afloramento no estado de Goiás e dois no estado do Tocantins. Foram utilizados procedimentos de descrição macromorfológica, micromorfológica e análise de espectrometria de fluorescência de raios-X com a finalidade de se obter dados relevantes a respeito dos processos atuantes durante o período de formação dos mesmos. O primeiro paleossolo (perfil SD) foi encontrado no município de São Domingos (GO) e marca o contato entre as Formações Posse e Serra das Araras, isto é, um momento de mudança ambiental, de deposição por dunas para deposição por lençóis de areia. Ele apresenta características hidromórficas, marcas de raízes e feições micromorfológicas como pedotúbulos, cutãs e glébulas. O segundo (perfil CV) foi encontrado em um corte de estrada entre Mateiros e Ponte Alta do Tocantins e estratigraficamente está no meio da Formação Serra das Araras. Ele apresenta intercalação de horizontes silicificados com não silicificados e apresenta cutãs, pedotúbulos, glébulas e cristalárias.O terceiro perfil (ES) está localizado na cidade de Mateiros (TO), no topo da Serra do Espírito Santo, que também corresponde ao topo da Formação Serra das Araras. O mesmo está fortemente cimentado por sílica de origem pedológica uma vez que existem feições pedológicas formadas por sílica, como silãs e cristalárias. Além destas estão presentes pedotúbulos e glébulas. A silicificação pedogenética, presente em dois paleossolos descritos indica um ambiente de formação árido a semiárido. De uma forma geral, os paleossolos encontrados são, seguramente, indicadores de condições climáticas extremamente quentes e secas na área do Grupo Urucuia durante o Cretáceo Superior. Localmente são capazes de fornecer dados mais confiáveis a respeito da posição na paisagem, vegetação e movimento de água pelo perfil, evidenciado pela frequência comum de cutãs formados não só por sílica, como também argila / Abstract: The Urucuia Group is located in the north central portion of the Sanfranciscana Basin and covers the states of Piauí, Bahia, Maranhão, Goiás, Tocantins and Minas Gerais. It is formed by a set of continental sandstones that date from the Late Cretaceous and deposited on a Phanerozoic bedrock and over Santa Fe and Posse Groups, both also located on Sanfranciscana Basin. The Urucuia Group consists of Posse and Serra das Araras Formations. The Posse Formation is characterized by deposits of sandy material in dune fields and braided fluvial system. Serra das Araras Formation was deposited on Posse Formation and is characterized by sand sheets and deposit of clasts. Since the area in which the Group is Urucuia is located virtually remained at the same latitude since the breakup of Gondwana, its paleoclimate records are related to climate change at the same latitude. The deposits indicate a desert situation that becomes increasingly wet though time. Environmental changes in the area were also recorded in paleosols of Urucuia Group. They were described in an outcrop in the state of Goias and two in the state of Tocantins. There have been used procedures of macromorphological and micromorphological description and X-ray Fluorescence Spectroscopy analysis with the purpose of obtaining relevant data about acting processes during their formations. The first palaeosol (profile SD) was found in the municipality of São Domingos (GO) and marks the contact between Posse and Serra das Araras Formations. This is, a time of environmental change, from deposits of dunes to deposits by sand sheets.He presents hydromorphic characteristics, root marks and micromorphological features as pedotubes, cutans and glebules. The second one (profile CV) was found in a road cut between Mateiros and Ponte Alta do Tocantins and stratigraphically is in the middle of Serra das Araras Formation. He has silicified horizons intercalated with non-silicified horizons and has cutans, pedotubes, glebules and crystals. The third profile, (ES) is located in Mateiros (TO), at the top of Serra do Espírito Santo, which also corresponds to the top of Serra das Araras Formation. It is strongly cemented with pedological silica and as there are soil features formed by silica such as silans and crystals. There are also pedotubes and glebules. The pedogenetic silicification is present in two paleosols that were described as formed in arid to semi-arid environments. In general, the found paleosols are indicators of an extremely hot and drought weather in the Group Urucuia area during Late Cretaceous. Locally they are able to provide more reliable data about their landscape position, vegetation and water movement in the profile, as evidenced by the common frequency of cutans formed not only by silica, but as well as by clay / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia

Sections in and around Badlands National Park, Custer County, South Dakota contain a wealth of faunal and floral data within the White River Group. The Chadronian and Orellan North American Land Mammal Ages define the Eocene-Oligocene boundary here. Faunal and floral changes associated with the Chadronian-Orellan interval have long been attributed to the global Greenhouse-Icehouse climatic transition. Stable isotopes were obtained from paleosol carbonates across the Chadronian-Orellan boundary at three locations in Badlands National Park. Results show wide fluctuations of oxygen isotopes in the uppermost Chadronian and lower Orellan, while carbon isotopes remain relatively stable. The records provide an opportunity to compare the continental response to global change with a near-shore marine system response (Gulf Coastal Plain, USA); and to the world at large. Results indicate a decoupling of the terrestrial response to the Oi-1 glacial event from the marine response. Local conditions appear to play an important role in controlling the record of stable isotopes in paleosol carbonates in the region. / Geologic history of the Eocene-Oligocene -- Climate records -- Causes of climate change -- Climate change across the Eocene-Oligocene -- Current findings -- Discussion. / Department of Geology

Ancient Cataclysmic Floods were the Ice Age Floods that left erosional and depositional features and preceded the Missoula Floods (15-18,000 ka) in the Pacific Northwest of the United States (Allen et al., 2009). All previously studied ancient sites were visited (14) and new sites (11) were found; four Missoula Flood quarries were also visited; a total of 29 sites were studied in this thesis. The use of calcrete paleosols to provide relative age dates for flood deposits was analyzed in this thesis. Missoula Flood gravel pits were sampled in order to examine the degree of calcrete development in flood deposits of known ages. All of the Missoula Flood deposits tested contain Stage 1 calcrete soil development. Calcrete paleosols at sites with evidence for older floods were all analyzed. Eight sites have paleosols with Stage II development (3-12% CaCO3): Rulo Outcrop, Potholes Coulee, Leslie Road, Benge, E. Callaway Road, Collier Coulee, Palouse, and Connell. Five sites have paleosols with Stage II+ development (12-17% CaCO3): Brown Road, Leslie Road, Benge, Reese Coulee, and Connell. Fourteen sites have paleosols with Stage III development (17-35% CaCO3): The Dalles, Rulo Outcrop, Winans Road 1, Poplar Heights, Yakima Bluffs, Canal Outcrop, Othello Canal, Reese Coulee, Potholes Coulee, E. Callaway Road, Frenchmen Coulee, Macall, Ritzville, and East Connell. One site has a paleosol with Stage III+ development (35-50% CaCO3): Othello Canal. Ancient Cataclysmic flooding initiated in the Early Pleistocene, at least 1.5 Ma. Sixteen field sites show evidence for Early Pleistocene flooding, preserved in all six provinces: Othello Channels, Columbia River Gorge, Cheney-Palouse Scabland, Quincy Basin, Pasco Basin, and the Walla Walla Valley. There are 26 field sites with evidence for Middle Pleistocene flooding, present in all regions except Othello Channels. Eleven of those 26 sites also show evidence for Early Pleistocene floods. Evidence for Early and Middle Pleistocene floods is present over a wide distribution of elevations from 117 to 524 meters.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Vaalputs radioactive waste disposal facility is situated in an arid region of Bushmanland currently with evapotranspiration potential that far exceeds precipitation. Dominant soil features in Vaalputs are palimpsests of climates under which they formed. Particle sizes vary drastically between horizons which suggest different modes of sediment transport. Petrographic analyses revealed euhedral habits of primary mineral feldspar within the soils of Vaalputs. This suggests a proximal source of sediments and minimal primary mineral weathering under an arid climate where euhedral grains of feldspar are maintained. The surface horizon of the soils is covered by an equigranular coarse sand of residual aeolian origin. The transition from the surface horizon to the subsurface horizons is widely marked by a pebble sized stone-line. The pebble sized material of the stone-line suggests residual accumulation during the weathering of a previously surface exposed horizon. Since deposition of subsurface sediments (15 Ma) pedogenic alteration has been active in Vaalputs. This has resulted to a complex soil system which displays varied forms of thick dorbank horizons including massive polygonal peds and platy horizons. The polygonal peds are defined by desiccation cracks where vertical and horizontal laminations are hosted. Slaking tests as well as bulk chemistry confirmed that the laminations are composed largely of secondary calcite, however elemental mapping revealed numerous illite bands alternating with calcite layers. It is proposed that calcite layers represent solution features rather than cutanic features. Signs of hydromorphy are commonly observed within the dorbank horizons, since an arid climate currently prevails in Vaalputs such hydromorphic features may indicate formation under past climates. The occurrences of palygorskite, sepiolite and dorbank horizons in Vaalputs require high soil pH (generated by high concentrations of Na) for their formation. Vaalputs soils, however, measured circumneutral pH and relatively low Na concentrations which suggests that palygorskite, sepiolite and dorbank horizons are relic features. Salt casts of lenticular texture occur between polygonal peds of massive dorbank horizons and their enveloping vertical and horizontal laminations. Scanning Electron Microscope analyses indicate high concentrations of Mg, Al, Si and O which suggests sepiolite and palygorskite accumulation through a replacement of gypsum. Elemental maps in conjunction with x-ray tomography and bulk chemical analyses revealed that high concentrations of secondary barite occur along the contact surfaces between dorbank horizons and the laminations. The solution chemistry of all horizons show supersaturation with respect to barite suggesting that the Ba accumulation adjacent to the laminations is likely to have taken place at lower sulphate conditions than those present in the soils today. Evidence shows that Vaalputs soils have experienced at least one climate shift. The preserved soil mottles are indicative of soil environments that remain wet for an extended period. A fine textured platy dorbank horizon is an extensive feature in Vaalputs. The presence of this horizon indicates that the sediments were deposited from a low energy fluvial system. The large polygonal ped units in the lower dorbank units as well as the barite enrichments in pore spaces suggests a climate shift from wet to dry began after the sediments were deposited. / AFRIKAANSE OPSOMMING: Vaalputs radioaktiewe afval fasiliteit is geleë in 'n ariede streek van Namakwaland met evapotranspirasie potensiaal wat neerslag tans ver oorskry. Dominante grond funksies in Vaalputs sluit in 'palimpsests‘ klimaat kondisies waaronder dit gevorm het. Deeltjies groottes wissel drasties tussen horisonne wat op verskillende vorme van sediment vervoer dui. Die oppervlak in Vaalputs word gedek deur 'n gelyke korrelagtige growwe sand van residuele eoliese oorsprong. Die oorgang vanaf die oppervlak horison na die ondergrondse horisonne word algemeen gekenmerk deur 'n spoelsteen grootte kliplyn. Die spoelsteen grootte materiaal van die kliplyn dui op residuele opbou gedurende die verwering van 'n voormalige oppervlak blootgestelde horison. Sedert afsetting van die ondergrondse sedimente (15 Mj) is pedogenetiese veranderinge reeds aktief in Vaalputs. Dit het gelei tot 'n komplekse grond stelsel wat verskillende vorme van dik dorbank horisonne insluitend massiewe veelhoekige pedons en plaatagtige horisonne vertoon. Die veelhoekige pedons word gedefinieer deur uitgedroogde krake waar die vertikale en horisontale lamellering aangetref word. Ontbindingstoetse sowel as heelrots chemiese analiese bevestig dat die lamellering grootliks bestaan uit 'n sekondêre kalsiet. Elementele kartering het egter talle illiet bande afgewissel met kalsiet lae openbaar. Daar word voorgestel dat kalsiet lae verteenwoordigend van oplossingskenmerke is eerder as kuntanise kenmerke. Tekens van hidromorfie word algemeen binne die dorbank horisonne waargeneem, aangesien droë klimaat tans in Vaalputs heers kan sulke hidromorfiese kenmerke dui op die vorming onder vorige klimate. Die groot voorkomste van paligorskiet, sepioliet en dorbank horisonne in Vaalputs vereis hoë grond pH (wat gegenereer word deur hoë konsentrasies van Na) vir hul vorming. Vaalputs grond het egter relatief neutrale pH gemeet en relatief lae Na konsentrasies wat daarop dui dat paligorskiet, sepioliet en dorbank horisonne oorblyfsel kenmerke is. Sout gietforme met lentikulare texture kom voor tussen veelhoekige pedons van massieve dorbank horisonne en hul omhullende vertikale en horisontale lamellerings. SEM analiese toon hoe konsentrasies Mg, Al, Si en O aan wat opbou van sepioliet en paligorskiet deur verplasing van gips voorstel. Petrografiese analiese het euhedraal geaardheid van primere veldspaat mineraal getoon binne die grond van Vaalputs. Dit stel 'n bron van sediment voor en minimale pedogenese in dorre klimaat waar euhedraal korrels veldspate bewaar bly. Elementele kartering tesame met x-straal tomografie en heelrots chemiese analiese het getoon dat hoe konsetrasies sekondere bariet langs die kontak oppervlakke tussen dorbank horisonne en lamellerings voorkom. Die oplossingschemie van alle horisonne toon superversadiging met betrekking tot bariet wat voorstel dat die opbou van Ba langs die lamellerings waarskynlik plaasgevind het by laer sulfaat kondisies eerder as die kondisies wat heedendaags in grond voorkom. Bewyse toon dat Vaalputs grond ten minste een klimaatsverandering ondergaan het. Die gepreserveerde grond vlekke is kenmerkend aan grond omgewings wat vogtig gebly het vir 'n geruime tyd. 'n Fyn getekstuurde plaatagtige dorbank horison is 'n uitgebreide verskynsel in Vaalputs. Die teenwoordiheid van hierdie dorbank toon aan dat sedimente vanuit 'n lae energie fluviale sisteem afgeset het. Die groot veelhoekige pedon eenhede in die laer dorbank eenhede sowel as die bariet verryking in porie spasies stel voor dat 'n klimaatsverandering vanaf vogtig na droog begin het nadat die sediment afgeset het.