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Testing the causes of middle Miocene Neotropical provinciality in South AmericaCatena, Angeline M., Catena 31 May 2018 (has links)
No description available.
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Vegetation and climate of north anatolian and north aegean region since 7 Ma according to pollen analysis / Végétation et climat des régions nord-anatolienne et nord-égéenne depuis 7 Ma d’après l’analyse polliniqueBiltekin, Demet 21 December 2010 (has links)
Cette étude concerne un long enregistrement sédimentaire marin (Site DSDP 380 : Miocène supérieur à Présent) et des affleurements à terre de dépôts marins ou lacustres du Miocène supérieur et(ou) du Pliocène inférieur. L’objectif principal de cette recherche est de reconstruire la végétation et le climat des régions nord-anatolienne et nord-égéenne des 7 derniers Ma. Deux types de végétation y furent alternativement : les forêts de plantes thermophiles et les formations ouvertes incluant les steppes à Artemisia. A la fin du Miocène, la plupart des éléments mégathermes (tropicaux) et mégamésothermies (subtropicaux) avaient régressé en raison des détériorations climatiques. Cependant, certains d'entre eux ont survécu pendant le Pliocène supérieur, notamment ceux qui constituaient des forêts littorals marécageuses (Glyptostrobus, Engelhardia, Sapotaceae, Nyssa) ou participaient à des forêts mixtes avec des arbres décidus mésothermes. Pendant ce temps, les formations ouvertes à herbes sont devenues prédominantes dans la végétation sans que les éléments steppiques (Artemisia, Ephedra, Hippophae rhamnoides) soient très abondants. A 2,6 Ma, sous l’effet des premières glaciations arctiques, les éléments méga-mesothermes se sont très raréfiés malgré la persistance de quelques reliques (Taxodiaceae : probablement Glyptostrobus, Engelhardia, Sapotaceae, Nyssa). Simultanément, les forêts mixtes à éléments mésothermes (Quercus décidus, Betula, Alnus, Liquidambar, Fagus, Carpinus, Tilia, Acer, Ulmus, Zelkova, Carya, Pterocarya, etc) ont aussi quasiment disparu tandis que les environnements steppiques se développaient fortement. Désormais, tout au long des cycles glaciaire-interglaciaire (d’abord de 41 ka de périodicité puis de 100 ka), les steppes à Artemisia occuperont plus d’espace temporel que les phases arborées. Depuis 1,8 Ma, les environnements à herbes et les steppes à Artemisia n’ont cessé de s’étendre jusqu' à aujourd'hui. Cette expansion des steppes à Artemisia dans la région du Pont-Euxin a été observée au tout début du Pliocène mais leur premier enregistrement en Anatolie date du Miocène inférieur. Le développement de la steppe à Artemisa en Anatolie pourrait résulter du soulèvement du Plateau tibétain. Le maintien dans cette région de plantes thermophiles reliques en situation de refuges (Carpinus orientalis, Pterocarya, Liquidambar orientalis, Zelkova) peut être expliqué par l’influence grandissante de la mousson asiatique dont le renforcement aurait aussi résulté du soulèvement du Plateau tibétain. / This study concerns a long marine section (DSDP Site 380: Late Miocene to Present) and onshore exposed sections from the Late Miocene and/or Early Pliocene. The main target of this study is to reconstruct vegetation and climate in the North Anatolia and North Aegean region for the last 7 Ma. Two vegetation types were alternately dominant: thermophilous forests and open vegetations including Artemisia steppes. During the Late Miocene, most of the tropical and subtropical plants declined because of the climatic deterioration. However, some of them survived during the Late Pliocene, such as those which constituted coastal swamp forests (Glyptostrobus, Engelhardia, Sapotaceae, Nyssa) or composed deciduous mixed forests with mesothermic trees. Simultaneously, herbaceous assemblages became a prevalent vegetation component despite steppe elements (Artemisia, Ephedra, Hippophae rhamnoides) did not significantly develop. At 2.6 Ma, as a response to the onset of Arctic glaciations, subtropical elements rarefied despite some taxa persisted (Glyptostrobus, Engelhardia, Sapotaceae, Nyssa). In parallel, deciduous mixed forest assemblages composed of mesothermic trees (deciduous Quercus, Betula, Alnus, Liquidambar, Fagus, Carpinus, Tilia, Acer, Ulmus, Zelkova, Carya, Pterocarya) almost disappeared too while steppe environments strongly enlarged. Then, Artemisia steppic phases developed during longer temporal intervals than mesophilous tree phases all along the glacial-interglacial cycles (first with a period of 41 kyrs, then 100 kyrs). Since 1.8 Ma, herbaceous ecosystems including Artemisia steppes still continuously enlarged up today. Such an expansion of Artemisia steppes in the Ponto-Euxinian region was observed at the earliest Pliocene but their earliest settlement in Anatolia seems to have occurred in the Early Miocene. The development of the Artemisa steppes in Anatolia might result from the uplift of the Tibetan Plateau. Relictuous plants such as Carpinus orientalis, Pterocarya, Liquidambar orientalis, Zelkova persisted up today. This story can be explained by some influence of the Asian monsoon which reinforced as a result from the uplifted Tibetan Plateau.
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A synthesis of Antarctic Neogene radiolariansRenaudie, Johan 19 June 2014 (has links)
Der Südozean ist die Schlüsselregion zur Kenntnis der neogenen Klimaentwicklung. In diesem Zusammenhang ist die Untersuchung von planktonischen Gemeinschaften in Hinblick auf die Umweltentwicklung von großer Bedeutung. In antarktischen neogenen Sedimenten sind Radiolarien reichlich, in großer Diversität und einheitlich gut erhalten. Sie sind nicht nur perfekte Testobjekte für paläobiologischen Studien, sondern auch eine wichtige Quelle für eine verbesserte Biostratigraphie – bisher behinderte nämlich das Fehlen einer verlässlichen Geochronologie detaillierte Studien. Es wurde ein Datensatz aller Taxa von mehreren Standorten des Südozeans gesammelt: für alle der 98 Proben je ca. 7000 Radiolarien. Die Fauna enthält ca. 500 Arten (inclusive 120 neuer Taxa). Die Untersuchung der Makroevolutionsgeschichte dieser Fauna zeigt, dass eine wesentliche ökologische Umwälzung, ohne Aussterbeereignis, bezogen auf den Verlauf der Artengleichheit und den Anstieg der Gattung Antarctissa, bei ca. 8 Ma erfolgte. Dann, 3 My später, folgte ein wesentlicher Diversitätsverlust. Obwohl das ökologische Ereignis eventuell mit einer Änderung der Primärproduzenten assoziiert sein kann, ist der auslösende Faktor des Diversitätsabfalls unbekannt. Außerdem zeigt der Vergleich zwischen der Diversitätsgeschichte dieser Fauna und einer Paläodiversitätsrekonstruktion südozeanischer Faunen, beruhend auf der Neptune Datenbank, daß der generelle Verläufe mit den Probenteilungsmethodologien nachgezeichnet wird, jedoch diese Methodologien aufgrund grober Verzerrungen nicht geeignet für Detailstudien sind. Schließlich wurde eine biostratigraphische Analyse für die komplette Fauna vom Obermiozän bis Pliozän durchgeführt. Obwohl diese Analyse noch vorlaüfig ist, zeigt sich eine Angleichung des aktuellen Altersmodells um mehr als 1 My. Diese Studie zeigt auch 94 neue, sichere Ereignisse, die für die stratigraphische Einordnung der Antarktischen Sedimente genutzt werden können. / The Southern Ocean is the key to understand the Neogene climate evolution. Unfortunately the lack of a robust geochronological framework has hindered precise studies. Equally of interest is understanding how planktonic communities changed in relation with the evolution of these environments. Radiolarians are abundant in Antarctic Neogene sediments, diversified and consistently well-preserved. They should constitute not only an ideal testing ground for paleobiological studies but also a major resource for improved biostratigraphy. In this study, a quantitative, taxonomically-complete dataset have been collected in various sites of the Southern Ocean, using 98 samples and ca. 7000 specimens per sample. Ca. 500 species were uncovered in this fauna, including 120 new to science. The study of the macroevolutionary history of this fauna reveals that a significant, extinctionless ecological turnover, linked to a decrease in the evenness of the species'' abundances and the rise of genus Antarctissa to dominance, occured at ca. 8 Ma, followed 3 My later by a significant diversity loss. Although the ecological event can be tentatively associated with a regional change in the composition of primary producers, the triggering event of the diversity loss is yet to be found. The whole-fauna diversity history was compared to paleodiversity reconstructions computed using subsampling methodologies from the occurrences gathered in the Neptune database. The comparison shows that the main trends are retrieved by the subsampling procedures but also that substantial distortions make them poorly suited for detailed studies. Finally a biostratigraphical analysis was conducted on this whole-fauna dataset for the late Miocene - Pliocene sequence. Although this analysis is still very much preliminary, it shows a coherent readjustement of the current age models by more than 1 My. This study also shows that 94 events seem reliable enough to be used to correlate Southern Ocean sites together.
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Exumação tectônica e evolução associada do relevo no arco de Ponta Grossa, sul-sudeste do Brasil /Franco-Magalhães, Ana Olivia Barufi. January 2009 (has links)
Orientador: Peter Christian Hackspacher / Banca: Antonio Roberto Saad / Banca: Francisco José Fonseca Ferreira / Banca: Gilmar Vital Bueno / Banca: Sandro Guedes de Oliveira / Acomapnah 4 mapas anexos / Resumo: A evolução do Arco de Ponta Grossa relaciona-se aos diversos eventos de reativação da Plataforma Sul-americana no sudeste brasileiro a partir do Cretáceo Inferior. A análise multi-métodos dos traços de fissão em apatita e zircão no eixo central do Arco de Ponta Grossa permitiu identificar períodos de exumação nas seguintes épocas: (1) Cretáceo Inferior (idades de traços de fissão em zircão entre 138 ± 51 Ma e 107 ± 22), relacionado aos processos tectônicos, magmáticos e de exumação do evento de ruptura do Gondwana Sul-Ocidental; (2) Cretáceo Superior (idades de traços de fissão em zircão entre 90 ± 14 Ma e 69 ± 21 Ma; e idades de traços de fissão em apatitas entre 74 ± 14 Ma e 66 ± 2 Ma), relacionado ao alçamento do embasamento cristalino como resposta à uma anomalia térmica causada pela passagem da Pluma de Trindade sob o sudeste brasileiro, e conseqüente geração tectônica de relevo e erosão que forneceu sedimentos para as bacias de Santos e do Paraná; (3) Cretáceo Superior - Paleoceno Inferior, evento tectônico relacionado a um soerguimento regional que resultou no alçamento e erosão das bordas das bacias da Plataforma Sul-americana, em especial a Bacia do Paraná. Este evento também é associado ao tectonismo gerador das bacias do Rifte Continental Sudeste do Brasil, no segmento central; (4) Oligoceno-Mioceno (idades de traços de fissão em apatitas entre 26 ± 3 Ma e 14 ± 2 Ma) há o registro da mais recente reativação das zonas de falha NW, em especial a Zona de Falha de São Jerônimo-Curiúva, associada ao rearranjo do campo de tensões neste período, e conseqüente erosão das porções de rocha, que marca o início da sedimentação no segmento sul do Rifte Continental Sudeste do Brasil, composto pela Bacia de Curitiba, grábens de Guaraqueçaba, Sete Barras e Cananéia; e as formações Pariqüera- Açu e Alexandra... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The evolution of Ponta Grossa Arch is genetically related to the post-rift reactivation of the South American Platform since Early Cretaceous. Apatite and Zircon lowtemperature thermochronology analysis in Ponta Grossa Arch provided the following interpretations: (1) Zircon fission-track ages between 138 ± 51 Ma and 107 ± 22are related to the tectonic, magmatic and exhumation processes occurred during the Gondwana breakup in Early Cretaceous; (2) Zircon fission-track ages between 90 ± 14 Ma and 69 ± 21 Ma, and apatite fission-track ages between 74 ± 14 Ma and 66 ± 2 Ma are evidenced the basement uplift as a response of thermal anomaly induced by Trindade plume since this time, as also evidenced in other areas of SE-Brazil during Late Cretaceous. The resulting highlands were the main source-area for the Coniacian-Maastrichian sediments of the Santos (Santos formation) and Paraná (Bauru Group) basins; (3) Between Late Cretaceous and Early Paleocene, the tectonic processes caused uplift and erosion of the Paleozoic interior basins, specially the Paraná Basin. At this time, preexisting shear zones were reactivated, formed the Continental Rift Basins of SE Brazil and continental sediments were deposited in these basins at the northern part of the study-area during this time; (4) During Oligocene to Miocene, apatite fission-track ages between 26 ± 3 Ma and 14 ± 2 Ma indicate the youngest reactivation of the NE-SW Precambrian shear zones and consequent exhumation of high elevated area. The origin of the Continental Rift Basins of SE Brazil in the study area (Curitiba basin, Guaraqueçaba, Sete Barras and Cananéia Grabens, and Pariquera-Açu and Alexandra formations) is probably related to the movement along NWSE trending fault zones (São Jerônimo-Curiúva Fault Zone). Thermal histories evidenced local and sea base-level stability and peneplanation processes caused dissection in highelevated areas. / Doutor
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Ιζηματολογική και γεωχημική μελέτη του σχηματισμού Μετόχια / Sedimentological and geochemical analysis of Metochia formationΠυλιώτης, Ιωάννης 08 May 2012 (has links)
Στόχος της παρούσας διατριβής είναι η μελέτη των ιζηματολογικών και γεωχημικών χαρακτηριστικών του νεογενούς σχηματισμού Μετόχια στην νήσο Γαύδο με κατεύθυνση την αναζήτηση πιθανών μητρικών πετρωμάτων υδρογονανθράκων.
Στο πρώτο κεφάλαιο γίνεται βιβλιογραφική ανασκόπηση της γεωλογίας της περιοχής μελέτης καθώς και γενικότερα της λεκάνης Μεσσαρά-Γαύδου, περιγραφή της τομής δειγματοληψίας και τέλος της γεωδυναμικής και παλαιογεωγραφικής εξέλιξης της ευρύτερης περιοχής.
Στο δεύτερο κεφάλαιο καταρχήν πραγματοποιείται μια επιγραμματική αναφορά των συνθηκών που απαιτούνται για την γένεση πεδίων υδρογονανθράκων και κατόπιν δίνεται έμφαση στα χαρακτηριστικά του οργανικού υλικού που εγκλωβίζεται στα ιζήματα και στον τρόπο δημιουργίας των μητρικών πετρωμάτων.
Στο τρίτο κεφάλαιο περιγράφονται οι γεωχημικές αναλύσεις που πραγματοποιήθηκαν. Το κεφάλαιο αυτό χωρίζεται σε δυο μέρη. Στο πρώτο περιγράφεται η ανάλυση ανθρακικού ασβεστίου και τα αποτελέσματα της. Στο δεύτερο μέρος παρουσιάζονται βιβλιογραφικά δεδομένα του ολικού οργανικού άνθρακα από την περιοχής της Μεσσαρά και τα αποτελέσματα της ανάλυσης του ολικού οργανικού άνθρακα καθώς και τα χαρακτηριστικά του οργανικού υλικού που προέκυψαν από την παρούσα διατριβή.
Στο τέταρτο κεφάλαιο γίνεται μια περιγραφή των μεθόδων κοκκομετρικής ανάλυσης που χρησιμοποιήθηκαν, η σύγκριση των μεθόδων, τα αποτελέσματα και η σύγκριση των αποτελεσμάτων που προέκυψαν.
Τέλος στο πέμπτο κεφάλαιο παρουσιάζονται τα αποτελέσματα της παρούσας διατριβής. / The aim of this thesis is to study the sedimentological and geochemical characteristics of the Neogene Metochia formation on the island of Gavdos towards the exploration for potential hydrocarbon source rocks.
The first chapter is a review of the geology of the study area and generally the geology of the Messara-Gavdos basin, a description of the sampling section and the geodynamic and paleogeographic evolution of the area.
In the second chapter a brief review of the conditions required for the genesis of hydrocarbons fields is provided, and then the characteristics of the organic material trapped in sediments and how source rock being creating, is emphasised.
In the third chapter the geochemical analysis don are described. This chapter is divided into two parts. First part describes the analysis of the total calcium carbonate and the results obtained. Second part presents bibliographical data for total organic carbon from Messara area samples and the results of the total organic carbon analysis derived from this thesis, as well as the characteristics of organic material of the studied samples.
The fourth chapter describes the grain-size analysis methods used in this thesis, a comparison of these methods, the results obtained and a comparison of them.
Finally in the fifth chapter the outcomes of this thesis are presented.
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Etude de l'expression de recombinases néogéniques dans le cancer colorectal / Study the expression of neogenic recombinases in colorectal cancerArnaoty, Ahmed 12 June 2013 (has links)
Le phénomène dit de domestication moléculaire qui a été rapporté pour certains transposons à ADN a abouti à la formation de néogènes qui codent des protéines potentiellement impliquées dans la stabilité du génome de part une activité recombinase. L’objectif de ce travail est d’étudier l’expression de 23 recombinases néogéniques d’intérêt dérivées de transpsons à ADN dans une série de cancers colorectaux. Nous avons fabriqué de nouveaux anticorps performants pour l’étude en western blot et en immunofluorescence de l’expression du gène SETMAR qui code pour la protéine Metnase dans des lignées cancéreuse différentes et dans des tissus du côlon tumoraux et normaux. Nos résultats démontrent que la vaccination d’ADN avec la formulation utilisée est une méthode qui donne de meilleurs résultats que l'injection de peptide ou protéines purifiées. Nous avons observé une expression de la protéine metnase dans des lignées cancéreuses de cancer du côlon, de leucémie et de cancer du sein. Le niveau d’expression de cette protéine Metnase dans le cancer du côlon semble être associé au statut MSI ce qui suggère un rôle de cette protéine dans les mécanismes de carcinogenèse et de progression tumorale. / During a phenomena known as molecular domestication has been reported for some DNA transposons leading to the formation of Neogenes which encode proteins potentially involved in the genome stability. The objective of this work is to study the expression of 23 neogenic recombinases of interest derived from DNA transpsons in a series of frozen colorectal cancers. We have manufactured new effective antibodies for the study of the expression of SETMAR gene which encode Metnase protein in different cancer cell lines and tissues of colon tumoral and normal by the method of Western blot and immunofluorescence. Our results demonstrate that DNA vaccination with the formulation used here is a method that gives better results than the injection of peptide or purified proteins. We observed an expression of Metnase protein in cell lines of colorectal cancer, leukemia and breast cancer. The level of expression of the Metnase protein in colon cancer appears to be associated to the MSI status which suggests a role for this protein in the mechanisms of carcinogenesis and tumor progression.
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Filogenia molecular e diversificação das arraias de ferrão de água doce (Família Potamotrygonidae) na América do SulRibeiro, Daniel Toffoli 09 October 2013 (has links)
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Previous issue date: 2013-10-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The network of South American rivers network has experienced deep changes during
Late Miocene through Pleistocene, including major marine transgressions, Andean uplift
driving drainage changes, and changes in eustatic level. After a marine transgression during
Late Miocene in northwest South America, the ancestor of freshwater stingrays
(Potamotrygonidae) adapted to the freshwater environment. Since then, the group has
diversified while colonizing new drainage networks, given rise to new phenotypes and diet
preferences. There are currently 24 species described, a number that will certainly rise once
new species already known are described and new geographical regions are sampled.
In the present work, I present a phylogeny for the Potamotrygonidae family based on
molecular markers, with estimates of age and statistical tests of changes in rates of
diversification while also testing for the occurrence of hybridization among some species of
the family. The pattern of diversification in time and space was interpreted in light of major
paleogeographical events that shaped drainage networks in South America during the
Neogene,
Mitochondrial and nuclear data corroborate the hypothesis of family origin in
northwest South America around 25 Million years ago (MYA), after a major marine
transgression, in a time when the Andes was not a topographic barrier between the
Caribbean Sea and coastal regions. After those hydrographic basins were differentially
colonized, whereas lineages that given rise to the genera Heliotrygon and Plesiotrygon
possibly originated in the Pebas System, the lineage that gave rise to Potamotrygon probably
was restricted to the region that is now the upper Negro river/Orinoco/Essequibo. After the
inversion of the proto-Amazonas direction from East-West to West-East and reorganization of
drainages, the Potamotrygon stingrays colonized both West portions of the Amazon Basin,
previously occupied by Pebas megawetlands, and an Eastern portion, previously isolated by
the Purus Arch. Contrary to the more accepted hypothesis, the estimated speciation ages
suggest that this reorganization occurred around 3 MYA. Alternatively, the inversion of proto-
Amazonas may have occurred earlier but the Negro river basin was kept isolated from the Amazon Basin at least as long to prevent stingrays dispersion.
Following the reorganization of the drainages, a group of Potamotrygon named spotocellated
underwent an increase in speciation rate – a radiation – as new regions were
colonized. Upstream colonization of Crystalline Shields probably occurred in periods of higher
eustatic level at the end of Pliocene, followed by vicariance after reduction of water levels.The
Paraguai-lower Paraná basin was probably colonized at this same time, after headwater
capture between Paraguai and Amazon Basins driven by foredeep formation. During the
radiation, extensive hybridization took place among species of the spot-ocellated group. / As redes de drenagem da América do Sul passaram por profundas transformações
do Mioceno Tardio ao Pleistoceno, incluindo grandes transgressões marinhas, soerguimento
dos Andes com consequente mudança nas redes de drenagem, e oscilações no nível
eustático. Após transgressão marinha no final do Mioceno no noroeste da América do Sul, os
ancestrais das arraias da família Potamotrygonidae adaptaram-se a água doce. Desde então
o grupo vem se diversificando à medida que coloniza novas redes de drenagem, com o
surgimento de novos fenótipos e adaptações a diferentes ambientes e dieta. Dado o
conhecimento taxonômico atual, existem cerca de 24 espécies na família, número esse que
certamente será elevado à medida que novas espécies já conhecidas forem descritas, e
novas regiões geográficas forem amostradas.
Neste trabalho, apresento hipótese filogenética baseada em marcadores moleculares
para a família Potamotrygonidae, com estimativa de idade dos eventos cladogenéticos e
testes de mudança das taxas de especiação. A ocorrência de hibridação entre algumas
espécies da família também foi testada. O padrão geográfico e tempo de diversificação das
arraias da família Potamotrygonidae foram interpretados à luz dos principais eventos
paleogeográficos que influíram nas mudanças das redes de drenagem da América do Sul
durante o Neógeno, eventos esses revisados aqui.
Os dados corroboram a hipótese de origem da família no noroeste da América do
Sul há aproximadamente 25 milhões de anos atrás, após grande transgressão marinha,
época em que os Andes ainda não serviam de barreira topográfica entre o Mar do Caribe e
as regiões costeiras dessa região. A partir daí as bacias hidrográficas foram diferencialmente
colonizadas, sendo que as linhagens que deram origem aos gêneros Heliotrygon e
Plesiotrygon possivelmente se originaram no sistema Pebas, enquanto que a linhagem que
deu origem ao gênero Potamotrygon provavelmente ficou restrito à região compreendida hoje
pelo alto Rio Negro/Oricono/Essequibo. Após a inversão do sentido do proto-Amazonas de
Leste-Oeste para o sentido moderno Oeste-Leste e reorganização das bacias de drenagem
que atingiram conformação próxima a atual, as arraias do gênero Potamotrygon colonizaram
tanto a região a Oeste da Bacia Amazônica, anteriormente ocupada pelas megawetlands do Sistema Pebas, quanto a região Leste, anteriormente isolada pelo Arco do Purus.
Diferentemente da hipótese mais difundida, as idades de especiação estimadas sugerem que
essa reorganização ocorreu há aproximadamente 3 milhões de anos atrás. Alternativamente,
a inversão do proto-Amazonas pode ter ocorrido antes, mas a bacia do rio Negro teria se
mantido isolada da bacia do rio Amazonas, ao menos a ponto de evitar a dispersão das
arraias.
Seguindo essa reorganização das drenagens, um grupo do gênero Potamotrygon
denominado roseta-ocelado sofreu um aumento na taxa de especiação – radiação – à
medida que novas regiões foram colonizadas. A colonização sentido rio acima das
drenagens dos Escudos Cristalinos provavelmente ocorreu em período de águas mais altas
no final do Plioceno, com posterior vicariância devido ao rebaixamento das águas. A Bacia
do Paraguai-baixo Paraná provavelmente foi colonizada nessa mesma época, possibilitada
pela conexão entre as cabeçeiras do rio Paraguai e Bacia Amazônica, após subsidência do
tipo foredeep desencadeada por soerguimento dos Andes. Durante o processo de radiação
do grupo roseta-ocelado houve extensiva hibridação entre as espécies do grupo.
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Étude des champs de contraintes néogènes à actuels des Alpes du sud : implications sur la géodynamique alpine et l’activité sismique / Study of the stress fields neogene to present day of Southwestern Alps : implications for alpine geodynamic and seismic activityBauve, Victorien 15 November 2013 (has links)
Ce travail de thèse présente une analyse géologique combinant plusieurs méthodes : géologie structurale des bassins néogènes et plio-quaternaires, inversion comparée des couples failles/stries et mécanismes au foyer ainsi qu’une l’analyse de la répartition spatiale et temporelle de la sismicité en relation avec la pluviométrie, avec pour objectif de comprendre quelle est la signification de l’activité sismique dans un système orogénique lent en prenant pour exemple le sud des Alpes Occidentales. Les principaux résultats sont les suivants : La région soumise à un raccourcissement nord-sud révélé par l’analyse et le caractère syn-tectonique des bassins miocènes et plio-quaternaires. La déformation est principalement accommodée par des systèmes décrochants N140 dextres. Ces systèmes décrochants concentrent la déformation active le long de structures héritées. On trouve de façon synchrone de l’extension (au nord-ouest du massif du Mercantour) et de la compression (au pied de la marge Ligure) le long d’un même système décrochant N140 dextre. La transition se fait progressivement, passant d’un régime transtensif au nord (dépression de Jausiers) vers un régime transpressif au sud qui s’explique par des permutations de contraintes. Cette géodynamique alpine est temporellement et cinématiquement reliée à une rotation continue de la micro-plaque apulienne et ce depuis le Miocène, contrôlée par l’ouverture des bassins ligure puis tyrrhénien. Le moteur de la tectonique active semble donc lié à la rotation de l’Apulie elle-même contrôlée par la subduction en Méditerranée. / This thesis aims at understanding the significance of seismic activity in a slow orogenic system with the example of the South Western Alps. It presents a geological analysis combining several methods and approaches: (i) a structural analysis of Neogene basins, (ii) a comparison of fault-striae data inversions with focal mechanisms and (iii) an analysis of the spatial and temporal distribution of seismicity in relation with rainfall. The main results are as follows: - The area is subject to a prolonged and globally similar through time north-south shortening context revealed by the analysis of the Miocene and Plio- Quaternary basins. The deformation is mainly accommodated by strike-slip dextral N140 faults. These strike slip faults focus the active deformation along inherited structures. - The geodynamic history of the S Alps is correlated with that of the Mediterranean back-arc basin opening. Extension (at the N-W end of Mercantour massif) and compression (at the foot of the Ligurian margin) occur along a dextral strike-slip system N140°E that might limit the Apulian block rotation. The transition is gradual, the regime evolves from a transtensive to a transpressive regime, from north to south, explained by permutations of stress inferred from fault-strea data analysis. - In this context of slow deformation, seismicity shows an annual periodicity correlated with the frequency and amount of rainfalls. This correlation can be explained by two processes that facilitate the triggering of earthquakes.
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Neogene stratigraphy of the Fish Creek-Vallecito section, southern California : implications for early history of the northern Gulf of California and Colorado DeltaWinker, Charles David, 1952- January 1987 (has links)
The Fish Creek-Vallecito section is the most stratigraphically complete and structurally intact Neogene exposure in the Salton Trough, and thus provides a useful reference section for regional stratigraphie revision and historical interpretation of the early Gulf of California and Colorado Delta. The section comprises a marine sequence (Imperial Formation) bracketed by nonmarine units (Split Mountain and Alverson Formations below, Palm Spring Formation and Canebrake Conglomerate above). Recognition of distinct suites of locally-derived and Colorado River-derived sediment, combined with sedimentological evidence, led to revision of this sequence in terms of informal members and geneticstratigraphic units: (1) pre-rift braided-stream deposits (2) syn-rift fanglomerates and volcanics, with local pre-marine evaporites; (3) pre-deltaic marine units, deposited primarily as small fan deltas; a progradational sequence of the ancestral Colorado delta, consisting of (4) an upward-shoaling marine sequence, and (5) a nonmarine deltaplain sequence; (6) lacustrine units; and (7) locally-derived basinmargin alluvium that interfingers with (4), (5) and (6). Neogene palinspastic base maps for paleogeographic mapping were based on displacement histories for the Pacific-North American plate boundary and its constituent faults. The tectonic-sedimentary history consists of: (1) early to middle Miocene rifting that propagated southward from southern California to the Gulf mouth; (2) northward marine transgression of the rift basin, reaching southern California by the late Miocene; (3) development of the San Andreas-Gulf of California transform boundary by inboard transfer of intraplate slip; (4) earliest Pliocene initiation of the lower Colorado River and Delta by rapid epeirogenic uplift of the Bouse Embayment; and (5) late Pliocene or Pleistocene transpressive uplift in the western Salton Trough caused by outboard transfer of slip from the San Andreas fault. The stratigraphic succession in the western Salton Trough resulted largely from tectonic transport through a series of paleoenvironments anchored to the North American plate by the entry point of the Colorado River.
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La evolución espacio- temporal de la cuenca de Lorca (Murcia). Aspectos geológicos y mineralógicosGuillén Mondéjar, Francisco 06 May 1994 (has links)
El estudio tectosedimentario, mineralógico, micropaleontológico y trabajo de campo (cartografía geológica, 1:18.000 y 17 columnas estratigráficas),de la cuenca neógena de Lorca (Murcia, España), ha permitido diferenciar sus cinco unidades tectosedimentarias (UTS), divididas en 12 formaciones marinas y continentales del Burdigaliense-Plioceno. La ausencia de dos UTS en el norte de la cuenca corrobora la existencia de una falla en el centro de la cuenca que fue clave en la evolución y el depósito disimétrico. El modelo tectónico de la cuenca de Lorca correspon¬de a un modelo híbrido entre pull-apart y graben. La distribución de espacio-temporal de los minerales, la morfología, asociaciones minerales y relaciones mutuas, han permitido conocer las áreas fuentes así como los procesos de transporte en cada UTS. Se concluye afirmando que el uso conjunto el análisis tectosedimen¬tario y mineralógi¬co permite un conocimiento más completo de la evolución e historia geológica de una
cuenca sedimentaria. / The complementary use of the mineralogical and tectosedimentary analysis of the tertiary Lorca basin (Murcia, Spain) we can characterize its tectosedimentary units (TSU) and the depositional sequences, establishing a tectonic-sedimentation model for this area. The Lorca basin has been defined as a hybrid between the pull-apart and graben models, with twelve formations, grouped in five TSU dated from the Burdigalian-Pliocene. The absence of two TSU at the north of the basin supported the existence of a fracture in the middle of the basin that has conditioned their space-temporal evolution and depositional disymetry. The analysis mineralogical: space-temporal distribution, morphology, mineral associations and mutual relationships, have allowed knowing the possible source areas as well as the processes of transport in each TSU. There are clear mineralogical differences among the five TSU established, which allows to affirming that this methodology contributes to a major knowled
ge of the evolution processes of a sedimentary basin.
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