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ESTRUTURA E DISTRIBUIÇÃO ESPACIAL DAS FLORESTAS RIPÁRIAS DO RIO PITANGUI, PARANÁ, BRASILNogueira, Melissa Koch Fernandes de Souza 13 September 2018 (has links)
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Previous issue date: 2018-09-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O rio Pitangui, de curso antecedente, é afluente da margem direita do rio Tibagi e
percorre três municípios (Castro, Carambeí e Ponta Grossa) da região centro-leste do
estado do Paraná. Embora todo o seu curso esteja submetido ao mesmo tipo
climático, Cfb de Köeppen, e mesma unidade fitogeográfica, Floresta Ombrófila Mista,
a diferença altitudinal e distintas litotipias representadas pelo degrau topográfico da
Escarpa Devoniana, e a consequente separação entre os Planaltos Paranaenses,
determinam diferenças geo-morfo-hidro-pedológicas marcantes. Foram selecionadas
dez estações amostrais ao longo do rio nos dois planaltos, e para cada estação foram:
a) alocadas nove parcelas de 5 x 10 m dispostas em três linhas paralelas à margem
do rio, onde foram mensurados e identificados todos os indivíduos com DAP ≥ 5 cm;
b) foram instalados e mensurados três poços hídricos (1,20 cm x 5,0 cm) e c)
realizadas análises químicas e físicas dos solos. Foi observado que a variação do
nível do lençol freático e a composição dos solos são os principais fatores
determinantes das variações florísticas e estruturais identificadas ao longo do curso
do rio. No Primeiro Planalto Paranaense (PPP), o Ambiente Ripário 1, caracteriza-se
por relevo plano sujeito a inundações permanentes ou periódicas, com vegetação
hidrófila a higrófila sobre solos hidromórficos a semi-hidromórficos. As espécies mais
importantes foram Sebastiania commersoniana, Erythrina crista-galli, Symplocos
uniflora e Sebastiania brasiliensis. Ainda no PPP, o Ambiente Ripário 2, constitui área
ecotonal com a Represa de Alagados, trata-se de um ambiente mais alçado, com
vertente moderada pouco sujeito a inundações, com vegetação mesófila sobre solos
não-hidromórficos, cuja espécie mais importante foi Nectandra grandiflora. No
Segundo Planalto Paranaense (SPP), o Ambiente Ripário 3, representado por relevo
plano a suave ondulado, com vegetação mesófila que se desenvolve sobre solos
preferencialmente não-hidromórficos. As espécies mais importantes foram Nectandra
grandiflora e Eugenia uniflora. Em todos os ambientes os solos são sempre ácidos,
com elevado conteúdo de carbono total nas camadas superficiais e percolação de
fósforo nas estações amostrais próximas a cultivos agrícolas. A distribuição dos
grupos funcionais de espécies mesófilas, higrófilas e hidrófilas se revelou bom
indicador da variação do nível freático. Na escala de paisagem percebe-se que os
fenômenos multiescalares seguem subordinados, ou seja, a modelagem do substrato
geológico determina a flutuação do freático e a formação e distribuição de solos, e
esse por sua vez, determina a cobertura vegetal. Estudos integrados desse porte
fornecem subsídios seguros para programas de restauração florestal em ambientes
ripários. / Pitangui is an antecedent river, a major right tributary of the Tibagi River, which crosses
three municipalities along the East-Central region of the State of Paraná. Although
being subjected to the same climate, Cfb of Köeppen, and same phytogeographic unit,
temperate forest, its altitudinal differences and distinct litotipies represented by the
Devonian Escarpment topographic slope, and the consequent separation between the
Paraná plateaus, determine remarkable geo-pedo-hydromorphological differences. It
was observed that the groundwater level variation and the soil composition are the
main drivers of floristic and structural variations among these riverine forests. On the
First Plateau (PPP), the Riparian Environment #1 is characterized by relief plan subject
to permanent or periodic flooding with hydrophylous or hygrophilous vegetation over
hydromorphic or semi-hydromorphic soils. The main species are Sebastiania
commersoniana, Erythrina crista-galli, Symplocos uniflora, and Sebastiania
brasiliensis. Yet in PPP, Riparian Enviroment #2 is an ecotonal area within Alagados
Reservoir. This is a more elevated one, subject to few floodings, with mesophylous
vegetation on no-hydromorphic soils, which main specie is Nectandra grandiflora. On
the Second Plateau (SPP), Riparian Environment #3 is characterized by relief plan to
slighltly undulating with mesophylous vegetation on soils preferably non-hydromorphic.
The main species are Nectandra grandiflora and Eugenia uniflora. In all environments
soils are ever acid with high contents of total carbon in the surface layers, as well
percolation of phosphorus next to agricultural crops areas. The functional groups
distribution among mesophilous, higrophilous, and hidrophilous species were good
indicators of the ground water level flutuation. On a landscape scale, multiescalar
phenomena are subordinated, as geological modeling determine ground water levels
as well soils orign and distribution. These one drives the vegetation settlement.
Integrated studies like this provide insurance subsidies for forest restoration programs
in riparian environments
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Évolution spatio-temporelle du couplage entre système fluviatile et rifting : étude du rift de Corinthe (Grèce) / Spatio-temporal evolution of the coupling between fluvial system and rifting : study of the Corinth rift (Greece)Hemelsdaël, Romain 06 October 2016 (has links)
Le comportement des rivières au cours du rifting joue un rôle important dans la sédimentation syn-rift et la distribution de la subsidence. Pendant la croissance des failles normales, les rivières répondent aux mouvements verticaux. En réponse au soulèvement tectonique, les rivières peuvent être déviées vers les zones en subsidence ou inversées. Les rivières peuvent aussi inciser les zones en soulèvement. L'évolution à long terme des rivières et leurs enregistrements stratigraphiques restent mal documentés pendant les processus de croissance et de migration des failles normales. Cette thèse analyse les interactions entre les rivières antécédentes et la croissance des réseaux de failles normales. Les implications en termes de distribution des faciès syn-rift sont étudiées à l'échelle du bassin et des blocs de failles. Les dépôts fluviatiles et deltaïques sont préservés dans plusieurs blocs de failles normales soulevés le long de la marge sud du rift de Corinthe (Grèce). Les logs sédimentaires et la cartographie des faciès syn-rift permettent le découpage lithostratigraphique de la zone d'étude. La série syn-rift est principalement conglomératique et difficile à dater. La magnétostratigraphie et quelques marqueurs biostratigraphiques sont utilisés pour dater et corréler les dépôts entre les différents blocs de faille. L'analyse des isotopes cosmogéniques 26Al et 10Be dans les dépôts a permis la détermination d'âge d'enfouissement. L'ensemble des âges obtenus par ces différentes méthodes permet de proposer un modèle de corrélation et de reconstruire l'évolution du rift précoce entre 3,6 et 1,8 Ma environ. (1) Le système fluviatile étudié évolue à travers plusieurs blocs de failles actives. (2) Le système de drainage antécédent hérité de la chaîne hellénique est caractérisé par un flux sédimentaire important depuis le début du rifting. (3) Le système fluviatile (au moins 30 km de long) remplit le paléorelief et le flux sédimentaire dépasse largement l'accommodation créée par les failles. L'enfouissement des failles par le système fluviatile limite la création de topographie et le développement d'un réseau de drainage conséquent. (4) L'axe fluviatile antécédent reste constant et contrôle la distribution des faciès. (5) Les changements de faciès et les architectures alluviales sont observés à l'échelle du bassin et ne sont pas directement contrôlés par les variations d'accommodation dans les blocs de failles. (6) Les zones d'accommodation maximale sont ici disposées parallèlement à l'axe fluviatile antécédent. La persistance des rivières et le flux sédimentaire pendant plusieurs centaines de milliers d'années ont permis la localisation de la déformation, induisant une rétroaction positive sur la croissance des failles. Le système distributaire se termine à l'est où des deltas progradent en milieu lacustre peu profond. Les systèmes de dépôts fluviatiles, deltaïques et turbiditiques actifs à l'initiation du rift de Corinthe enregistrent l'approfondissement diachrone du bassin. Le comportement des rivières antécédentes est aussi étudié à l'échelle d'une zone de relais entre deux failles bordières actuellement actives. Pendant le Pléistocène moyen et supérieur, la zone de relais a capturé la rivière antécédente de Krathis qui a construit une succession de deltas. La connexion entre les deux failles majeures est marquée par (1) des failles obliques dites "de transfert", (2) plusieurs familles de terrasses marines enregistrant le soulèvement diachrone de la rampe de relais, et (3) la migration progressive de l'accommodation vers le bassin. Cette étude permet pour la première fois de reconstruire les processus de connexion de failles sur une période 0,5 Ma. La rivière Krathis persiste au cours du développement de la zone de relais et met en évidence, une fois de plus, l'importance des rivières antécédentes dans la localisation des dépocentres majeurs dans les rifts / Rivers behaviour during early rifting can significantly impact on syn-rift sedimentation and the distribution of subsidence. During normal fault growth, existing rivers can be diverted toward subsiding zones. They can respond to footwall uplift either by reversing their flow or by incising into uplifting zones. Long-lived river systems and their stratigraphic record in rifts are poorly documented, not only during early fault propagation and linkage processes but also during successive migrating phases of fault activity. We investigate the interactions of major antecedent rivers with a growing normal fault system and the implications for facies distributions, both on a basin scale and at the scale of individual normal fault blocks. Along the southern margin of the western Corinth rift (Greece), the Plio-Pleistocene fluvial and deltaic successions are investigated. Syn-rift deposits are preserved in a series of uplifted normal fault blocks (10–20 km long, 3–7 km wide). Detailed sedimentary logging and high resolution mapping of the syn-rift deposits document variations of alluvial architecture across the basin and enable to define lithostratigraphic units. Magnetostratigraphy and rare biostratigraphic data are used to date and correlate the alluvial succession between fault blocks. Burial ages were tentatively determined using cosmogenic isotopes 10Be and 26Al produced in situ in quartz grains. Based on the correlation model, we reconstruct the evolution of the early western Corinth rift between about 3.6 and 1.8 Ma. (1) The transverse and antecedent Kalavryta river system flowed and deposited across a series of active normal fault blocks. (2) This river system was inherited from the Hellenide mountain belt and supplied high volumes of coarse sediments from the onset of extension. (3) As depocentres enlarged through time, the fluvial deposits progressively filled palaeorelief. A continuous braided plain developed above active buried faults and no significant consequent drainage system developed between the narrow fault blocks. (4) The main fluvial axis of the antecedent drainage persists through time and controlled facies distribution. (5) The length scale of facies transitions is greater than, and therefore not related to fault spacing. Here, along-strike subsidence variations in individual fault blocks represent a secondary contributor to the alluvial architecture. (6) The zones of maximum subsidence on individual faults are aligned across strike, parallel to the persistent fluvial axis. This implies that long-term sediment supply and loading influenced normal fault growth. Sediment supply largely outpaced local hangingwall subsidence and overfilled the early rift basin. The river system terminated eastward where small deltas are built into a shallow lake that occupied the central Corinth rift. During this time, another river system built fan deltas along the southern margin, recording diachronous deepening of the basin. The behaviour of antecedent rivers is also studied at the scale of a relay zone, that developed later in the rift history between two growing fault segments. During the Middle to Late Pleistocene, the relay zone captured the antecedent Krathis River, which deposited prograding Gilbert-type deltas. Transfer faults record progressive linkage and basinward migration of accommodation along the ramp axis, while marine terraces record diachronous uplift in their footwalls. Although early linkage occurred, the main normal faults continued to propagate until final connexion. For the first time a reconstruction of the linkage phase is presented over a period of ca. 0.5 Myr. Throughout this linkage history, the Krathis River continued to flow across the relay zone. Again, this emphasizes the role of antecedent rivers in supplying sediments and controlling the location of the major depocentres along the rift margins
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