Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-10Bitstream added on 2014-06-13T19:33:31Z : No. of bitstreams: 1 tinos_tm_me_rcla.pdf: 5695071 bytes, checksum: 73966c119954aa9e5c17bad30f038d2d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O mapeamento geológico-geotécnico é um instrumento fundamental para o planejamento e gestão do meio físico, fornecendo as informações essenciais para a tomada de decisão. Este trabalho teve como objetivo a elaboração de um mapa geológico-geotécnico das principais áreas urbanas e de expansão do município de Poços de Caldas - MG. A metodologia empregada focou a análise integrada dos elementos do meio físico a partir do uso de fotografias aéreas e trabalhos de campo, para a compartimentação fisiográfica de unidades do terreno. A etapa seguinte foi a caracterização geotécnica de cada unidade e uma avaliação de adequabilidade quanto ao uso urbano. Como produtos finais são apresentados um mapa geológico-geotécnico da área, um perfil de cada unidade, além de suas principais características e processos geológicos ocorrentes. Tais elementos são instrumentos essenciais para o planejamento urbano e territorial do município / The geological-geotechnical mapping is a fundamental tool for planning and managing the physical environ, providing essential information for decision making. This study aimed to development a geological-geotechnical map of Poços de Caldas major urban areas and expansion. The methodology focused on the integrative analysis of the physical environ and the use of air photographs to section the area by physiographical features. The next step was the geotechnical characterization of each unit and an assessment of their capabilities and limitations as to urban use. As a final products are presented a geological-geotechnical map of the area, a profile of each unit, besides its main characteristics and geological processes occurring. These elements are essential tools for urban and territory planning of the municipality

Made available in DSpace on 2014-06-11T19:32:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-30Bitstream added on 2014-06-13T19:42:48Z : No. of bitstreams: 1 gomes_ar_dr_rcla.pdf: 3426893 bytes, checksum: 9fdd90dbe50b0c722b6ab95832537e05 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Com a expansão das atividades de petróleo e gás, o transporte destes produtos precisa ser monitorado para permitir o abastecimento e preservar as paisagens sobre as quais o transporte é realizado e uma das formas mais recomendadas para o Brasil é através de dutos, devido à distância entre a produção e os centros de consumo. Para esta pesquisa foi selecionado um trecho na faixa de dutos Rio de Janeiro – Belo Horizonte para avaliar as potencialidades de dados Fine QuadPol do RADARSAT-2 no mapeamento do uso e cobertura da terra sobre diferentes condições geomorfológicas. A partir das matrizes de coerência e covariância dos dados Fine QuadPol foram realizadas análises da decomposição de alvos (Cloude-Pottier e Freeman-Durden) e classificadores de Wishart derivados destas decomposições. Para os dados em amplitude, foi utilizado o classificador MaxVer-ICM. Para todos os resultados também foi analisado o efeito da aplicação do filtro polarimétrico de Lee com janelas 5x5 e 7x7 pixels. Foram estabelecidas 11 classes de uso e cobertura da terra (nível 2) e realizada uma análise exploratória baseada nos dados em sigma zero e parâmetros resultantes das decomposições de Cloude-Pottier e Freeman-Durden (anisotropia, entropia, ângulo alfa, contribuições dos espalhamentos superficial, double-bounce e volumétrico). Como a separação das classes não foi possível para o nível 2, optou-se por manter o nível 1 onde são mapeadas somente as classes de cobertura da terra. Com base nos resultados alcançados pelos classificadores, pode-se dizer que o MaxVer-ICM apresentou o maior índice de concordância kappa (38%) enquanto o classificador de Cloude-Pottier teve o pior desempenho (19%). Os classificadores de Wishart obtiveram kappa de 27% para a Wishart derivada de Cloude-Pottier e 25% para... / Due to the expansion of the activities of oil and gas, the transportation of these products must be monitored to allow the supplies and preserve the landscapes on which transport is carried out and one of the most recommended forms of transport to Brazil is through pipelines due to distance of the consumers centers. For this research was selected a stretch in the Rio de Janeiro - Belo Horizonte pipelines to evaluate the potential of QuadPol Fine RADARSAT-2 data for mapping land use and land cover on different geomorphological conditions. From the covariance and coherence matrices of Fine QuadPol data was performed target decomposition (Cloude-Pottier and Freeman- Durden) and Wishart classifiers derived from these decompositions. For amplitude data, MaxVer-ICM was used as classifier. For all results was also analyzed the effect of applying Lee polarimetric filter with windows of 5x5 and 7x7 pixels. It was established 11 land use and land cover classes (level 2) and performed an exploratory analysis based on data from sigma nought and parameters resulting from the decomposition of Cloude and Pottier-Freeman-Durden (anisotropy, entropy, alpha angle, contributions from surface, double-bounce and volume scattering ). As the separation of classes was not possible to level 2, we chose to keep a level where they are mapped only the classes of land cover. Based on the results achieved by the classifiers, we can say that the ICMMaxVer had the highest rate of agreement kappa (38%) while the classifier Cloude- Pottier had the worst performance (19%). Wishart classifiers obtained kappa of 27% for the Wishart from Cloude-Pottier and 25% for the Wishart from Freeman-Durden. Based on the classifiers from the target decomposition and different parameters have presented results more visually... (Complete abstract click electronic access below)

O mapeamento geológico dos depósitos siliciclásticos aflorantes nas bacias marginais do nordeste brasileiro tem gerado um alto volume de designações estratigráficas ainda abertas às discussões. No intuito de subsidiar a resolução deste problema cartográfico foi escolhida a parte emersa da Bacia Paraíba, mais especificamente as sub-bacias Alhandra e Mirirí. Para isto foi realizada a caracterização mineralógica e petrográfica dos arenitos cenozóicos da Bacia Paraíba, com vistas a identificação de critérios discriminadores entre os diversos depósitos siliciclásticos aflorantes. Derivado deste processo é acrescentado o reconhecimento das áreas fontes desses arenitos e suas implicações na evolução do Cenozóico da Bacia Paraíba. Análises laboratoriais incluíram análises granulométricas, de minerais pesados e morfológica de grãos em 134 amostras de superfície e subsuperfície. Foram estudadas também 5 seções delgadas para testar a petrografia sedimentar como ferramenta no auxílio do mapeamento geológico. A identificação dos minerais pesados transparentes foi feita através microscópio petrográfico, com quantificação dos principais minerais transparentes (100 grãos/lâmina), além de várias contagens independentes (100 grãos/lâmina) das relações transparentes/opacos, do par rutilo/zircão e sobre as formas e grau de arredondamento de zircão e turmalina. Em superfície foram mapeadas como unidades siliciclásticas de base para topo a Formação Barreiras (Mioceno), Depósitos Pós-Barreiras I (Neopleistoceno) e Depósitos Pós-Barreiras II (Holoceno). Em subsuperfície, o furo estudado atravessa toda seção cenozóica e mesozóica, inclusive as unidades basais da bacia, as formações Beberibe e Itamaracá. A mineralogia acessória é dominada por minerais opacos com porcentagens superiores a 60% em todas as unidades. Em toda sucessão cenozóica, as assembléias de minerais transparentes são muito homogêneas e apresentam como minerais principais zircão, turmalina, cianita e rutilo e, subordinadamente, estaurolita, andaluzita, topázio e anfibólios cálcicos. Ocorrem como traços sillimanita, epidoto, monazita e granada. Em subsuperfície, no entanto, na unidade basal é reportada a existência de granada como mineral principal. A análise de formas de zircão e turmalina permitiu diferenciar, tanto em superfície como em subsuperfície, os depósitos estudados. Em termos gerais, existe um maior grau de arredondamento das formas de zircão e turmalina na direção do topo das unidades. Os dados de petrografia, ainda que poucos, apontam diferenças texturais, composicionais e inclusive diagenéticas entre os arenitos aflorantes na bacia. Esta ferramenta mostrou-se promissora para a caracterização das unidades da bacia. A mineralogia acessória em superfície não permite diferenciar as unidades aflorantes, mas, em subsuperfície, mostra que a Formação Beberibe tem uma assinatura de granada que a caracteriza muito bem e permite concluir, de maneira categórica, que esta unidade não aflora na área estudada. Os resultados do estudo de formas em zircão e principalmente em turmalina permitem diferenciar as unidades aflorantes pelo grau de arredondamento dos grãos, o que evidencia uma reciclagem sedimentar inclusive das unidades cretáceas. Este dado é reproduzível em subsuperfície, onde as categorias euédricas concentram-se nas unidades basais. Assim, considera-se que as principais fontes para os depósitos cenozóicos são resultantes do retrabalhamento de unidades sedimentares preexistentes, e subordinadamente, de fontes primárias relacionadas às rochas metamórficas da Zona Transversal da Província Borborema. / The geologic mapping of siliciclastic deposits which outcrop in the marginals basins of Brazilian northeast have generated a high volume of stratigraphic designations that are opened to actual discussions. In order to solve this cartographic problem, the emerging part of the Paraiba basin was chosen, specifically the sub-basins of Alhandra and Mirirí. For this reason were realized the mineralogic and petrographic characterizations of the Cenozoic sands and sandstones of the Paraiba Basin, with the purpose of identifying the discriminating criteria between the diverse siliciclastic deposits. Additionally were realized the recognition of the sandstones´ source areas and its implications in the evolution of the Paraíba Basin in the Cenozoic times. The laboratory analysis included heavy minerals, granulometric, morphology from grains in 134 surface and subsurface samples. Five thin sections were studied to testify the sedimentary petrography as a tool for geological mapping. The identify of heavy minerals was done under petrographic microscope for species descriptions, with counting of 100 grains per slide. Several independent counts (100 grains/slide) of the ratio transparent/opaque, the rutile/zircon index and shape and grain roundness of the zircon and tourmaline were also done. On the geological mapping, the siliciclastic units were considered, from the base to the top, Barreiras Formation (Miocene), deposits Post-Barreiras I (Neopleistocene) and deposits Post-Barreiras II (Holocene). On subsurface, the drill hole studied crosses through the whole Cenozoic and Mesozoic stratigraphy of the basin, including the basal units (Beberibe and Itamaracá formations). The accessory mineralogy is dominated by opaque heavy minerals with higher percentages than 60% in all units. In the whole Cenozoic succession, the assembly of transparent heavy minerals is very homogeneous and is essentially composed by zircon, tourmaline, kyanite and rutile, containing also staurolite, andalusite, topaz and calcic amphibole subordinately. Sillimanite, epidote, monazite and garnet occur as a trace minerals. Otherwise, on subsurface, garnet is reported as a principal mineral in the basal unit. The analysis of zircon and tourmalines shapes allowed to distinguish all the studied deposits. In general, the grade of roundness in grains of zircon and tourmaline increases to the top of succession. The petrografic data showed textural, compositional and diagenetic differences between the cropping out sands - sandstones of the basin. This tool seemed to be a promising to characterize the stratigraphic units of Paraíba Basin. The accessory mineralogy permitted to distinguish the Beberibe Formation, which is well characterized by the presence of garnet. On the other hand, the absence of garnet in the described sandstones let to conclude the Beberibe Formation not exposed in the mapped area. The data from shape studies in grains of zircon and tourmaline allowed to differentiate the cropping out units by the roundness grade, evidencing a sedimentary recycling, including the Cretaceous units. This data is reproducible on subsurface samples where the euedrical categories are concentrated on the basal units. At last, the main sources of the Cenozoic deposits are considered to be reworked preexistence sedimentary units, and subordinately, the primary sources comprise the metamorphic rocks from Transversal Zone of Borborema Province.

Orientador: José Eduardo Zaine / Banca: Cenira Maria Lupinacci da Cunha / Banca: Frederico Garcia Sobreira / Resumo: O mapeamento geológico-geotécnico é um instrumento fundamental para o planejamento e gestão do meio físico, fornecendo as informações essenciais para a tomada de decisão. Este trabalho teve como objetivo a elaboração de um mapa geológico-geotécnico das principais áreas urbanas e de expansão do município de Poços de Caldas - MG. A metodologia empregada focou a análise integrada dos elementos do meio físico a partir do uso de fotografias aéreas e trabalhos de campo, para a compartimentação fisiográfica de unidades do terreno. A etapa seguinte foi a caracterização geotécnica de cada unidade e uma avaliação de adequabilidade quanto ao uso urbano. Como produtos finais são apresentados um mapa geológico-geotécnico da área, um perfil de cada unidade, além de suas principais características e processos geológicos ocorrentes. Tais elementos são instrumentos essenciais para o planejamento urbano e territorial do município / Abstract: The geological-geotechnical mapping is a fundamental tool for planning and managing the physical environ, providing essential information for decision making. This study aimed to development a geological-geotechnical map of Poços de Caldas major urban areas and expansion. The methodology focused on the integrative analysis of the physical environ and the use of air photographs to section the area by physiographical features. The next step was the geotechnical characterization of each unit and an assessment of their capabilities and limitations as to urban use. As a final products are presented a geological-geotechnical map of the area, a profile of each unit, besides its main characteristics and geological processes occurring. These elements are essential tools for urban and territory planning of the municipality / Mestre

Acompanha 2 mapas anexos / Orientador: José Eduardo Zaine / Banca: Odaléia Telles Marcondes Machado de Queiroz / Banca: George Luvizotto / Resumo: Esta dissertação objetivou principalmente a elaboração de um mapa de unidades geoambientais, ou seja, um produto cartográfico onde os elementos do meio físico são estudados a partir da análise integrada para a determinação de potencialidades e limitações dos terrenos. O mapeamento geoambiental aliado à cartografia geotécnica fornece informações fundamentais sobre o meio físico, o que é essencial para subsidiar instrumentos de gestão pública, na definição do uso adequado de áreas naturais, como os pontos turísticos. A área estudada compreende uma porção de 220 km² da Bacia Hidrográfica do Rio Camanducaia, no município de Amparo, que foi escolhido pela sua condição de Estância Hidromineral localizada em área serrana e com isso abrigar áreas de intensa atividade turística. A partir da interpretação de fotografias aéreas e compartimentação fisiográfica foram delimitadas zonas geoambientais, balizadas pelos estudos regionais de geomorfologia e geologia. Com a elaboração de mapas preliminares (Declividades, Hipsométrico e Modelo de elevação de terreno) foi possível compreender as variações altimétricas, além da morfologia do relevo. O produto final, o Mapa de Unidades Geoambientais, apresenta a área dividida em sete unidades: 1) planícies aluviais, 2) rampas colúvio-eluviais, 3) migmatitos em relevo de morrotes e morros, 4) gnaisses e migmatitos em relevo de morros, 5) gnaisses e migmatitos em topos de morros, 6) quartzitos em relevo montanhoso e 7) depósito de tálus e colúvio em sopé de montanha. Todas as unidades foram caracterizadas detalhadamente e descritas suas limitações e potencialidades à ocupação urbana e desenvolvimento do turismo no município / Abstract: The main objective of this study was to generate a map of geo-environmental units, ie, a cartographic product in which the elements of the physical environment are studied based on integrated analysis to determine capabilities and limitations of the land. Geoenvironmental mapping combined with geotechnical cartography provides key information on the physical environment, which is essential to support public management tools in defining the appropriate use of natural areas such as tourist places. The study area covers a portion of 220 km ² of Camanducaia River Basin in Amparo, São Paulo State, which was chosen for its condition hydromineral spa located in mountainous area and thereby comprise areas of intense tourist activity. From the interpretation of aerial photographs and compartmentalization of physiographic zones were delimited geoenvironmental, buoyed by regional studies of geomorphology and geology. On the development of preliminary maps (slope, hypsometric and elevation terrain model) it was possible to understand the altimetric variations, and the morphology of the relief. As result, it was obtained an Unit Geoenvironmental Map, that presents the area divided into seven units: 1) floodplains, 2) eluvial-colluvial slopes, 3) migmatites in relief and hillock hills, 4) gneisses and migmatites in relief of hills, 5) gneisses and migmatites on the tops of hills, 6) in quartzite mountainous and 7) deposit of talus and colluvium at the base of the mountain. All units were characterized in detail and its limitations and potential urban to settlement was described / Mestre

Este trabalho discute os resultados de pesquisa direcionada à elaboração de mapa geotécnico do perímetro urbano e de sua área de expansão no município de Jaú (SP). O método de mapeamento aplicado baseia-se na utilização de geofatores para a classificação das áreas quanto ao grau de restrição à ocupação urbana, conforme proposto originalmente por Matula (1976). Os mapas produzidos foram classificados em 1ª, 2ª, 3ª e 4ª ordens conforme sugerido por Mathewson & Font (1974). Em todo o trabalho fez-se uso de sistema de informações geográficas - SIG como ferramenta básica para o armazenamento e análise dos dados de interesse, e a produção dos mapas. A pesquisa insere-se no aprimoramento das técnicas e métodos para fornecer os subsídios do meio físico para os instrumentos de planejamento urbano e municipal, e em particular, os planos diretores. Os estudos foram desenvolvidos na escala principal de trabalho de 1:10.000. / The paper discusses the results of a research focusing on the elaboration of engineering geological map comprising the urban perimeter and its expansion area in the Jaú city, located at São Paulo state, Brazil. The mapping method is based on the utilization of the geofactors to classify the restriction degree for urban occupation, such as originally proposed by Matula (1976). The produced maps had been classified in the 1st, 2nd, 3rd and 4th orders suggested by Mathewson & Font (1974). Geographic information system GIS was employed to store to analyze the concerned data and to produce the maps in all the stages of the work. The research aims to improve the techniques and the methods to supply inputs related to physical environment to the urban and municipal planning instruments detaching the managing plans. The studies are being carried out at the main scale of 1:10.000.

Este trabalho apresenta um método de mapeamento geológico-geotécnico baseado no método da Escola de Engenharia de São Carlos/USP, porém modificado para incorporação dos aspectos considerados positivos do método utilizado pelo Instituto de Pesquisas Tecnológicas do Estado de São Paulo e do detalhamento progressivo, utilizado pela UNESP-Rio Claro. O método proposto é adequado para trabalhos de diagnóstico das características geológico-geotécnicas de interesse para o gerenciamento do uso do solo, principalmente para o planejamento municipal e elaboração de planos diretores. O método foi aplicado ao município de Analândia - SP e permitiu a proposição de diretrizes para o gerenciamento do uso do solo no município como um todo, que foi mapeado na escala 1:50.000, e na área de expansão urbana, mapeada na escala 1:10.000, por ter sido identificada como a região do município onde os processos geológicos, notadamente erosão acelerada, apresentam maior tendência de crescimento. / This essay presents an engineering geological mapping method based on the method used by the Escola de Engenharia de São Carlos (EESC) of the São Paulo University (USP), which also incorporates the positive aspects of two other methods currently used in São Paulo state: the one used by Instituto de Pesquisas Tecnológicas (IPT) and the so called progressive detailing method, used by the UNESP-Rio Claro. This method aims at composing a diagnosis of the geological and geotechnical aspects of the natural environment and providing the information on it in a way that planners find of value for planning land use in urban and rural areas. It has been used in the municipality of Analândia-SP and it allowed the formulation of the directions for land use in the whole municipality, which has been mapped in a regional scale (1:50.000), and in the urban area, which has been mapped in a more detailed scale (1:10.000), once it has been identified as the area where geological processes, remarkably soil erosion, have increased most in recent years.

M.Sc. (Geography) / Landsat TM and SPOTMSS data were analysed and classified using two different procedures and the resulting maps were evaluated with respect to land use in the Sandton urban-rural fringe. The Landsat TM data consisted of 6 spectral bands (0,45-0,52, 0,52-0,60, 0,63-0,69, 0,760,90, 1,55-1,75, 2,08-2,35 IJm). The SPOT MSS data (one image taken in summer and one in winter) consisted of 3 spectral bands (0,50-0,59, 0,61-0,68, 0,79-0,89 IJm). The data from the two systems were stretched statistically so that all bands showed similar spread on both sides of the median. A ground truth map was obtained from the Sandton Town Council against which the final land use maps derived from Landsat and SPOT were compared for accuracy. The satellite data were analysed in two steps to compile the land use maps: The first step was a cluster analysis based on ISODATA of Ball and Hall (Ball, m..al, 1965). The result were 3 maps with 34, 30 and 35 spectral classes for Landsat TM and the SPOT seasonal images. The next step was a combination of cluster analysis and nearest-neighbour analysis. Examples of the land uses required for the final maps were chosen and for each a histogram of spectral classes was compiled. A nearest-neighbour analysis was done to determine how many pixels of the same class lie next to each other. All the pixels in the spectrally classified image were viewed in conjunction with the surrounding pixels; a histogram and nearest-neighbour analysis was done for each. The results were then compared to that of the land use examples and each pixel was allocated to the land use class which it most resembled. The evaluation involved a computerised comparison of the land use maps with the ground truth map obtained from the Sandton Town Council. The final results were three different land use maps, each created with one image (Landsat TM, SPOTsummer, or winter images). The land use classes identified on each map were: agricultural holdings; high density residential areas; low density residential areas; townhouses (only from the SPOTimages); a combination of commercial and industrial areas; parks; unused land; recreational areas. Comparative use of the two satellite based data acquisition systems leads the author to conclude that: Landsat TM was best for mapping agricultural holdings and high density residential areas; the SPOT summer image was best for mapping townhouses, parks, unused land and recreational areas, the SPOT winter image was best for mapping low density residential areas and commercial/industrial areas. Both systems may be regarded as data sources for urban research, for the mapping of land use in urban-rural fringes. The result of this study is the provision of an easily updated land use map of the Sandton urban-rural fringe to aid effective planning and control where future development will take place.

In tropical areas, the high rainfall induces severe-and pervasive weathering, producing a thick soil cover. The lithologies underneath may b~ recognised using geochemical mapping, which is based on certain elements that have the ability to differentiate between various lithologic units. Elements that are independent of the weathering process are normally selected for this purpose. The chemistry of mobility of base metals is an important factor to take into account when evaluating the mobility and distribution of these elements in a soil profile. Factors such as pH, Eh, organic material, clay minerals, Fe and Mn oxides are normally key aspects to be considered. When iron-rich rocks undergo deep weathering, lateritic profiles are developed. These are widespread in a belt bordering the equatorial zone, including the Brazilian shield, West and East Africa, parts of India and Northern Australia. In these profiles, the high rainfall promotes intense leaching of the different horizons. Where the pre-existing profiles are mostly preserved, the base metals are distributed throughout the profile: in the upper ferruginous horizon, goethite and hematite can adsorb large amounts of Mo, resulting in large dispersion halo. Other base metals such as Cu and Zn are less resistant in these freely-drained profiles and, therefore, they may be partly leached from the profile. In the lower horizons, Cu, ,zn, Ni and Co are retained, hosted in kaolinite and smectite, and thus, a high geochemical contrast will be identified in this horizon at the expense of a decline in the size of the dispersion haloes. The pre-existing profiles can be truncated, with a thin stone line developing at the contact between the lateritic profile and the recent soil. The conditions in these environments favour the retention of most of the pathfinder and target elements in all soil horizons, with the B horizon showing the highest contrast. If the primary rock is rich in AI, a bauxitic profile will be developed. The world distribution of bauxites closely resembles that of laterites. The behaviour of Co and Ni is very similar to that of iron during the bauxitization. Furthermore, the factors that induce residual enrichment of Al with removal of Fe in the soil profile will cause significant depletion of Co and Ni in these profiles. These metals are then concentrated at the base of the profile because of precipitation from downward percolating solutions. Many karst bauxite deposits in Southern Europe are enriched with Ni and Co in the basal horizon. Such horizon is mined as nickel ore in the bauxites of the Lokris region in Greece. Copper and molybdenum are strongly enriched.in bauxitic profiles. Concentration ratios are 8 and 3.2 for Cu and Mo respectively. Molybdenum is closely related to goethite and hematite, and therefore, the high concentration of Mo in a bauxitic profile will be consistent with the horizon where iron is concentrated. Copper concentrates at the base of the iron rich-horizon but also appears enriched in the saprolite together with Co. When sulphide bodies occur, in this environment, deep and penetrative weathering has resulted in considerable near-surface mobilization of iron and silica. The supergene alteration commonly obscures the identity of the primary sulphides at the surface. In this case, geochemical assessment of the resulting gossan has proved to be crucial in mineral exploration. A search in the secondary mineral assemblage, volatile and precious metals may lead to the information on the composition of the primary sulphide assemblage. The conclusion that will be reached is that if the geochemical properties (mobility, affinities with Fe or Mn oxides and/or clay minerals) of each of the base metals are understood, an appropriate sampling (optimum size-depth combination) will then be done. In such cases, a subdued, weak, but significant, geochemical response will be identified in the surface horizon.

In the Paleoproterozoic Trans-Hudson Orogen, a well exposed section of mid-crust on Hall Peninsula, southeastern Baffin Island, offers an opportunity to improve our understanding of mid-crustal tectonothermal processes in hot, collisional orogens. Additionally, more robust age constraints on the tectonic history of Hall Peninsula are important for plate tectonic reconstructions of the North Atlantic region. Recent mapping shows that the section comprises Archean crystalline basement overlain by Paleoproterozoic supracrustal rocks, which host felsic plutons on the western peninsula. There is a westward increase in peak metamorphic grade, from amphibolite- to granulite-facies, and three regional deformation events are recognized (D1, 2, 3). Equilibrium phase diagram modeling constrained by garnet compositions in pelite indicates peak conditions of ~720–740°C on the eastern peninsula and ~850°C further west, with pressures of ~6.25–7.35 kbar. Modeling and petrographical evidence suggest subsequent cooling, decompression, growth of retrograde biotite and, on the eastern peninsula, retrograde muscovite. In situ U-Pb monazite dating (~450 analyses) and U-Pb zircon depth profiling (~90 analyses) resolve the timing of regional metamorphism and crustal shortening between ca. 1860–1820 Ma, coincident with the accretion of crustal blocks and arc terranes during the amalgamation of the orogenic upper (Churchill) plate. Regionally-occurring ca. 1800–1750 Ma monazite domains and zircon rims are interpreted to result from fluid-assisted dissolution-reprecipitation. They likely record the terminal collision with the lower-plate Superior craton and post-orogenic thermal activity, possibly related to the emplacement of pegmatitic syenogranite dykes. The new data strengthen formerly tentative correlations with southern Baffin Island, West Greenland and northern Labrador. 40Ar/39Ar thermochronology on muscovite, biotite and phlogopite suggests that Hall Peninsula underwent slow cooling at rates of ~1–2.5ºC/Myr after peak metamorphism, remaining hotter than ~400°C until ca. 1670–1660 Ma. Analogous thermochronological ages from elsewhere in the Trans-Hudson Orogen imply orogen-wide slow cooling. Despite significant crustal thickening and elevated paleotemperatures, the Hall Peninsula crustal section does not record evidence of orogenic collapse, implying that it may not be a hallmark of all hot, thickened orogens.