Search

Anthropogenic climate change risks significant changes in the global distribution of precipitation. Across the western United States, modelling studies show significant reductions in wetness that imply weighty societal and ecological impacts. But the validity of the model projections need to be ground-truthed. Paleo-hydroclimate data are useful reference points to assess a model’s ability to hindcast past hydroclimate. If the hindcast matches the paleodata, it brings confidence to a model’s ability to predict future hydroclimatic change. The foremost metric of hydroclimate in the geologic record is the surface area of lakes in hydrologically closed basins. In such basins, a lake’s surface area is determined by the balance between precipitation and evaporation. The lake will expand when the balance is positive, and it will contract when the balance is negative. In this dissertation, I develop a 25-9 ka record of lake fluctuation from the Mono Basin, a hydrologically closed basin in east-central California. I deduced the fluctuations using three pieces of evidence: stratigraphy; geomorphology; and geochronology. These pieces of evidence were determined from a study of the Mono Basin’s Late Pleistocene lithostratigraphic unit: the Wilson Creek Formation. There are 19 tephra intercalated in the Wilson Creek tephra. They are named by their reverse depositional order (Ash 19 is the oldest and Ash 1 is the youngest). Uncertainty on their ages cause confusion as to the paleo-hydroclimate record of the Mono Basin. The age of Ash 19, for example, is important because its deposition marks the onset of relatively high lake levels that occurred during the last glaciation. There are two principal interpretations of Ash 19’s age: 40 ka, which is based on lacustrine macrofossil 14C data; and 66 ka, which is underpinned by paleomagnetic intensity data. In chapter 2, I tested these end-member interpretations. I used the U/Th method to date carbonate deposits that underlie and cut across Ash 19. The U/Th data show that Ash 19 must have been deposited between these two dates: 66.8 ± 2.8 ka; and 65.4 ± 0.3 ka. These dates are, therefore, more consistent with the 66 ka interpretation of Ash 19’s age. Thus the onset of relatively high lake levels in the Mono Basin corresponds with the rapid drawdown of atmospheric CO2 during Marine Isotope Stage 4. The coincidence between the drop in atmospheric CO2 and lake level rise is suggestive of a causal link. In chapter 3, I determined Mono Lake's fluctuations 25-9 ka. This time encompasses three climatic intervals: the coolest time of the last glaciation, termed the Last Glacial Maximum (LGM); the period corresponding to the rapid termination of the last glaciation, termed the deglaciation; and the early Holocene, a period of inordinate warmth that immediately followed the last glaciation’s termination. In this study, I used stratigraphic and geomorphic evidence in conjunction with 14C and U/Th dates. I measured the 14C dates on bird bones and charcoal. And I measured the U/Th dates on carbonates. Together the data showed that the lake's rises and falls concurred with North Atlantic climate. Periods of aberrant warmth in the North Atlantic concurred with low stands of Mono Lake. On the other hand, extreme cooling in the North Atlantic correlated with Mono Lake high stands. The timing of these lake fluctuations also corresponds with variations in other tropical and mid-latitude hydroclimatic records. The global harmony in the hydroclimatic records suggests a unifying conductor. I hypothesize that the conductor is tropical atmospheric circulation. In chapter 4, I present evidence on the peculiar case of an extreme low stand of Mono Lake. The low stand is dubbed the “Big Low”. The principal evidence underpinning the Big Low derives from a sedimentary sequence exposed along the canyon walls of Mill Creek. The strata show that the lake fell below 1,982 m between the deposition of Ashes 5 and 4—making this low stand the lowest recognized level of Mono Lake during the Wilson Creek Formation. Observations from dispersed sequences corroborate this interpretation. And three data constrain the age of the Big Low to be between ~24.4-20.5 ka: a carbonate U/Th date on a littoral conglomerate associated with the Big Low; a carbonate U/Th date that underlies Ash 4; and a carbonate U/Th date that cuts across Ash 5. Thus the interval that the Big Low must occur within encompasses the LGM. The timing of this low stand, therefore, corresponds with summer temperature minima, suggesting that the fall was due not to an increase in evaporation but due to a decrease in precipitation. This finding is counter to conventional wisdom: that the LGM was a relatively wet interval. In addition, both the documentation of a low stand during glacial maximum conditions and the inference that precipitation must have been reduced are contrary to previous published interpretations from model and paleoclimatic data. These discrepancies raise significant questions about our understanding of the regional expression and forcing of hydroclimate across the western United States during the LGM. Because of this period’s importance to ground-truthing climatic models, additional evidence on the geographic extent of this unexpected result is essential.

Orientador: Maria José Maluf de Mesquita Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin Resumo: As metodologias de aprendizagem ativas, nas quais os estudantes protagonizam o próprio processo de construção do conhecimento, são fundamentais ao desenvolvimento intelectual autônomo. Dentre as tendências metodológicas, há a Aprendizagem Baseada em Problemas - ABP, do original Problem Based Learning - PBL, consagrada na Educação Superior pelos resultados positivos, mas pouco investigada na Educação Básico, especialmente no Brasil. A presente pesquisa procurou diagnosticar como se dá e quais são os limites e potencialidades do desenvolvimento de aulas adaptadas à metodologia da ABP, via conteúdos curriculares geocientíficos, em uma turma do nono ano do Ensino Fundamental II, de uma escola pública da cidade de Campinas, São Paulo. Investigou adaptações por meio de atividades baseadas nos princípios da ABP, em temas com enfoque na Origem e Evolução do Universo, da Terra e da Vida. Para tal, foi levantado um histórico da consolidação da metodologia, das suas características e particularidades, e elaborado um Plano de Aprendizagem. As aulas foram desenvolvidas durante quase um bimestre escolar, de acordo com um cronograma pré-estabelecido, e a experiência foi socializada na Unidade Escolar, junto a todo o corpo docente. Com base em produções, avaliações e autoavaliações dos alunos, caderno de campo, filmagem das atividades, socialização com o corpo docente e entrevista com o professor titular da disciplina de Ciências, analisou-se e discutiu-se uma dinâmica adaptada da ABP com relação a: a) infraestrutura e particularidades organizacionais da Unidade Escolar; b) habilidades relacionadas ao desenvolvimento de atividades em equipes; c) preparo e contribuições ao docente, incluindo os relatos da entrevista do professor titular, e; d) construção de conhecimentos geocientíficos com um olhar interdisciplinar. As contribuições dos docentes, durante a socialização, foram consideradas e igualmente compuseram as análises e discussões. A realização da dinâmica de ABP, dentro da realidade das escolas públicas estaduais, foi o primeiro resultado positivo da experimentação. As considerações finais apontam sinais de êxito em relação à dinâmica adaptada das variantes da ABP, além de: i) detecção de poucas deficiências na infraestrutura escolar, que não inviabilizaram a execução da dinâmica; ii) identificação de habilidades de colaboração e autonomia (pré-requisitos ao princípio das atividades em grupos) nos alunos do final do Ensino Fundamental II e, em desenvolvimento, as de administrar o tempo e de sistematização; iii) percepção, por parte dos alunos, do próprio processo de maturação intelectual, via autoavaliação; iv) reflexão da pesquisadora-professora sob o preparo das aulas e o processo de ensino-aprendizagem; v) alterações no modo da abordagem das aulas subsequentes (professor titular), porém com relatos de apreensão ao uso de algumas etapas adaptadas da ABP (docentes da Unidade Escolar), e; vi) os temas geocientíficos tenderam aos escolarizados e a construção de conhecimentos surgiu como consequência de todo o processo. Deste modo, acreditamos que investigações sobre o desenvolvimento da ABP no Ensino Básico, fornecem subsídios para motivar os docentes a novas experiências com metodologias de aprendizagem ativas Abstract: The active learning methodologies, in which the students protagonise their own knowledge construction process, are fundamental to the autonomous intellectual development. Among the methodological tendencies, there is a Problem Based Learning - PBL, established in Higher Education by your positive results, but few used in Middle School, particularly in Brazil. The present research sought to diagnose how it takes place and what the limits and potentialities of the PBL methodology, through geoscientific curricular contents, adapted to a ninth year of middle public school class of the city of Campinas in the São Paulo State in Brazil. This research investigated adaptations through activities based on the principles of PBL, in themes focusing on the Origin and Evolution of the Universe, Earth and Life. In order to do it we developed the methodology consolidation history, its characteristics and peculiarities, and a Learning Plan for the school dynamic. The classes were developed during almost a two-month period of the School calendar, according to a pre-established schedule, and the experience was socialized in the School Unit, with all school teachers. The adapted dynamics of the PBL was analyzed and discussed based on productions, evaluations and the students' self-assessments, field work notebook, filmed activities, school teacher¿s socialization sciences discipline main teacher interviews. The main topics to discuss are: a) infrastructure and organizational features of the School Unit; b) skills related to the team-based activities; c) preparation and contributions to the teacher, including reports of the teacher¿s interview, and; d) construction of geoscientific knowledge with an interdisciplinary approach. The contributions of the teachers during the socialization were considered and composed the analyzes and discussions. The first positive result of the experimentation was the PBL dynamic¿s development and conclusion, within the reality of the state's public schools in Brazil. The final considerations pointed to success signs in relation to the adapted dynamics of the PBL variants, in addition to: i) the detection of only few deficiencies in the school's infrastructure, which did not invalidate the execution of the dynamics; ii) the recognition of the student¿s collaboration and autonomy skills (prerequisites to the principle of team activities) in the students of the end of Middle School Term and, in development, the skills of managing time and thinking systematization; iii) the students¿ perception of the process of intellectual maturation, through self-assessments; iv) the researcher-teacher¿s reflections about the classes¿ preparation and teaching-learning process; v) changes in the approach of the subsequent classes (by the main sciences teacher), however with personal apprehension accounts to the use of some adapted steps of the PBL (teachers of the School Unit), and; vi) the geoscientific subjects trended to the scholar standards and the knowledge construction arose as a consequence of the whole process. Therefore, we believe that the PBL development researches in Basic Education provides subsidies to motivate teachers to new experiences inactive learning methodologies Doutorado Ensino de Ciências e Matemática Doutora em Ensino de Ciências e Matemática CAPES

As decomposers, fungi are key players in recycling plant material in global carbon cycles. We hypothesized that genomes of early diverging fungi may have inherited pectinases from an ancestral species that had been able to extract nutrients from pectin-containing land plants and their algal allies (Streptophytes). We aimed to infer, based on pectinase gene expansions and on the organismal phylogeny, the geological timing of the plant-fungus association. We analyzed 40 fungal genomes, three of which, including Gonapodya prolifera, were sequenced for this study. In the organismal phylogeny from 136 housekeeping loci, Rozella diverged first from all other fungi. Gonapodya prolifera was included among the flagellated, predominantly aquatic fungal species in Chytridiomycota. Sister to Chytridiomycota were the predominantly terrestrial fungi including zygomycota I and zygomycota II, along with the ascomycetes and basidiomycetes that comprise Dikarya. The Gonapodya genome has 27 genes representing five of the seven classes of pectin-specific enzymes known from fungi. Most of these share a common ancestry with pectinases from Dikarya. Indicating functional and sequence similarity, Gonapodya, like many Dikarya, can use pectin as a carbon source for growth in pure culture. Shared pectinases of Dikarya and Gonapodya provide evidence that even ancient aquatic fungi had adapted to extract nutrients from the plants in the green lineage. This implies that 750 million years, the estimated maximum age of origin of the pectin-containing streptophytes represents a maximum age for the divergence of Chytridiomycota from the lineage including Dikarya.

Paleomagnetic methods have been used in economic geology to date mineralization in sediment-hosted ore deposits and thereby help to develop ore deposit models and understand the geodynamic settings in which mineralization can occur. However, paleomagnetic ages are sometimes inconsistent with other geochronological techniques and with geological observations. Here we test the veracity of paleomagnetic ages for sediment-hosted ores through a study of the Irish Midlands ore field. We find that unaltered rocks distal to mineralization that are of equivalent age to the ore host sequence have comparable characteristic remanent magnetic directions to those previously derived from the ores. This indicates that remagnetization of the rocks was probably independent of the ore-forming process. Comparison with the apparent polar wander path for Europe suggests an age of ca. 310 Ma for this event, consistent with the timing of the Variscan orogeny. Fold test results support this, indicating the signal was acquired after tilting and/or folding of the host rocks. Petrology and magnetic data suggest that nanometric magnetite particles are the remanence carrier. Based on independent geochronological and geological constraints, we conclude that mineralization formed in Ireland in the early Carboniferous coincident with basin development and that paleomagnetic dates were reset during the later orogenic overprint. Caution is therefore warranted in the interpretation of paleomagnetic dates for ore systems, and geodynamic models for mineral systems based on these may be erroneous.

The aim of this study is taxonomie investigation and environmental distribution of ostracoda association from the bottom sediments of the Mediterranean (The Gulf of Antalya) and Aegean Sea (Alibey and Maden islands/Ayvalik and Kuşadasi) and identification of species surviving up to present. Twenty genera and 26 species are determined by examining the ostracoda contents of the 197 samples from the bottom sediments from 5 to 30 m depth in the Antalya Bay (Mediterranean). 24 genera and 34 species in 84 samples belonging to 4 cores around Alibey and Maden islands to the north of Ayvalik in Aegean Sea have been determined. Also, 23 genera and 29 species from the 45 samples at the depth of 8,5-22.3 m around Kuşadasi have been determined. According to carapace morphology and depth of water, shallow marine group genera are belonging to subfamilies Trachyleberidae and Hemicytheridae which have well-developed hinge, branching marginal-pore canals, clear eye-spots and more ornamentation, are relatively abundant specimens. The ostracoda association defined in this study is correlated with previous studies in Mediterranean, Aegean islands, Adriatic Sea, Algeria, Aegean and Marmara Sea of Turkey. The well-known ostracoda species such as Aurila convexa, Jugosocythereis prava, Carinocythereis antiquata, Carinocythereis carinata, Costa batei, Semicytherura inversa, Loxoconcha rhomboidea, Sahnia fasciata, Cushmanidea elongata from Atlantic and Mediterranean and Neonesidea formosa, Triebelina raripila, Cytherella (Cytherelloidea) beckmanni, Cytherelloidea sordida, Aurila arborescens, Carinocythereis rhombica, Hiltermannicythere rubra, Hiltermannicythere turbida, Cytheretta adriatica, Cytheretta judaea, Callistocythere intricatoides, Urocythereis crenulosa, Acanthocythereis hystrix, Paracytheridea depressa, Xestoleberis communis, Xestoleberis dispar and Pontocypris acuminata from in Mediterranean are wide-spread.

A set of closely related basaltic lava flows (supersite GA-X) on Floreana Island in the Galapagos Archipelago has a published record of an excursional or transitional direction (virtual geomagnetic pole located at 153.1°E, 54.2°S with α₉₅ = 5.0°) and a geomagnetic field strength (1.1 × 10²² Am²) that is only ∼14% of the strength of the modern magnetic field (7.8 × 10²² Am²). The very large age uncertainty of previous dating of a lava flow (G43) from this set, however, has prevented placing this event in the geomagnetic polarity time scale. Here we report highly reproducible and precise ⁴⁰Ar/³⁹Ar ages on the lava flow that indicate that the distinct geomagnetic excursion is 925.7 ± 4.6 ka (2σ; n = 6; mean square of weighted deviates = 1.23). This shows that this dramatic weakening of the geomagnetic field is associated with the Santa Rosa Excursion instead of the Matuyama-Brunhes polarity reversal. Our high-precision ⁴⁰Ar/³⁹Ar ages for Floreana provide evidence for the global significance of the Santa Rosa Excursion.

Agradecimentos: The work presented here was funded by Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP, Brazil under Grants [2012/07243-3, 12/15824-6 and 2014/04920-0]. VKS is thankful to DST, Gov. of India, for providing the financial support as Grants (project no. INT/ILTP/B-2.72 and project no. SR/S4/ES-339/2008). Prof. A.I. Slabunov (Petrozavodsk, Russia) is acknowledged for thoughtful discussions. We are grateful to the two reviewers (Vinod O. Samuel, and anonymous) and the editor (M. Santosh) for their insightful comments and suggestions to improve our presentation Abstract: The central Bundelkhand greenstone complex in Bundelkhand craton, northern India is one of the well exposed Archaean supracrustal amphibolite, banded iron formation (BIF) and felsic volcanic rocks (FV) and associated with grey and pink porphyritic granite, tonalite–trondhjemite–granodiorite (TTG). Here we present high precision zircon U–Pb geochronological data for the pinkish porphyritic granites and TTG. The zircons from the grey-pinkish porphyritic granite show three different concordia ages of 2531 ± 21 Ma, 2516 ± 38 Ma, and 2514 ± 13 Ma, which are interpreted as the best estimate of the magmatic crystallization age for the studied granites. We also report the concordia age of 2669 ± 7.4 Ma for a trondhjemite gneiss sample, which is so far the youngest U–Pb geochronological data for a TTG rock suite in the Bundelkhand craton. This TTG formation at 2669 Ma is also more similar to Precambrian basement TTG gneisses of the Aravalli Craton of north western India and suggests that crust formation in the Bundelkhand Craton occurred in a similar time-frame to that recorded from the Aravalli craton of the North-western India FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Fechado

Se presenta una estrategia didáctica para la enseñanza - aprendizaje del concepto de fósil, a partir de fósiles hallados en Colombia. El trabajo se desarrolló con base en el modelo de escuela activa y juegos didácticos. La propuesta fue aplicada a estudiantes de ciclo cuatro de la Institución Educativa Distrital Villamar. Abstract: This document present a teaching strategy, to learning concept fossil from fossil found in Colombia. The work was developed based on the model of active school and educational games. The proposal was applied to students of cycle four of School: Institución Educativa Distrital Villamar. Maestría

The Kermadec Arc-Havre Trough (KAHT) is widely regarded as a classical example of an intra-oceanic arc-back-arc system, where subduction-driven arc magmatism is focused at the Kermadec volcanic arc-front, and magmatism within the Havre Trough back-arc system results from decompression-related melting. In detail, however, the Havre Trough has not been well-studied, and data for very few lavas have been reported. Recent mapping undertaken in the southern Havre Trough has resulted in the discovery of several prominent submarine stratovolcanoes, Gill Seamount, Rapuhia Seamount and the related Rapuhia Ridge, Yokosuka Seamount, and Giljanes Seamount, situated in the middle of deep rifts and on elevated crustal plateaux. The origin and evolution of these stratovolcanoes is unknown. The first detailed dataset of whole rock major and trace element geochemistry, mineral chemistry, and ⁴⁰Ar/³⁹Ar isotope data, for lavas erupted from these volcanoes is presented here, and used to investigate the processes that drive volcanism in the Havre Trough back-arc. ⁴⁰Ar/³⁹Ar ages obtained from back-arc stratovolcanoes range from ca. 1167 - 953 ka for Gill Seamount, and ca. 107 - 50 ka for Rapuhia Ridge. These ages overlap with known ages for arc-front lavas, indicating that both back-arc and arc-front volcanism are coeval. These ages are all significantly younger than the inferred initation of Havre Trough rifting ca. 5 - 6 Ma. Lavas analysed from Gill Seamount and Rapuhia Ridge are basaltic to basaltic-andesitic in whole rock composition and contain a phenocryst assemblage of olivine ± orthopyroxene + clinopyroxene ± plagioclase. Lavas from Rapuhia Seamount, Yokosuka Seamount and Giljanes Seamount range from andesitic to dacitic in composition, and have a phenocryst assemblage consisting primarily of plagioclase ± clinopyroxene ± amphibole ± Fe-Ti oxides ± apatite. Variations in mineral assemblages and whole rock compositions of the lavas are consistent with crystal fractionation of thei

Liminality permeates this doctoral project's questions: how can an experience of the liminal exist as an artwork? What things and experiences can orient us towards affectivity and states of becoming? Lisa Tan relates such concerns to Clarice Lispector whose writing renders becoming(s) visible. Coupled with Maurice Blanchot and his literary discourse on dispossession and the outside (analogous to becoming), Tan's inquiry is critically engaged inside a moving image practice. A suite of videos: Sunsets, 2012; Notes From Underground 2013; and Waves 2014-15, stand as the primary output of this dissertation. Drifting between day and night, above and below ground, land and sea, they exist as movements towards the fulfillment of the promise of the liminal: transformation. In Sunsets, the sun converses with the force that is Clarice Lispector. The video documents the audio of a casual translation of an interview with Lispector from 1977. This recording forms the video's soundtrack. The visual footage is comprised of scenes that were filmed at 3 o’clock in the morning during the summer or 3 o’clock in the afternoon during the winter in Sweden. Notes from Underground connects the Stockholm metro and Susan Sontag’s sojourn in Sweden with a cavern system 5,000 miles away in New Mexico. The video suggestively links this journey to experiences of liminality, narrating varied intensities of geological time and strata of personal and cultural history. Departing from Virginia Woolf’s novel The Waves, Tan’s video Waves imagines how consciousness forms in relation to society and its technologies, but also to expressions of geological and hydrological processes. Filmed at the threshold of land and sea, a conversation forms between disparate hydro-relations, such as Woolf’s prose, Courbet’s paintings of waves, Google’s data centers cooled by the Baltic Sea, invisible jellyfish, and transoceanic cables. The dissertation includes the videos, a doctoral thesis, and an artist's book, containing: illustrated transcriptions of each video; a documented solo exhibition; texts by Mara Lee, Lauren O’Neill-Butler, Natascha Sadr Haghighian, and Lisa Tan. The artist's book both documents and reflects on the research performed and involves the voices of others, providing a critical, intersubjective understanding of liminality. List of components in the dissertation: Artworks: Sunsets (2012) HD video, sound 22 min. 45 sec. Notes From Underground (2013) HD video, sound 23 min. 45 sec. Waves (2014-15) HD video, sound 19 min 12 sec. Solo exhibition of video installations Lisa Tan: For every word has its own shadow Galleri Riis, Stockholm, Sweden January 14-February 21, 2015 Artist's book Lisa Tan: Sunsets, Notes From Underground, Waves Editor: Joshua Shaddock Publisher: Archive Books, Berlin, 2015 Doctoral Thesis Lisa Tan For every word has its own shadow: Sunsets, Notes From Underground, Waves Doctoral dissertation in Fine Arts at Valand Academy, Faculty of Fine, Applied and Performing Arts, University of Gothenburg Publisher: ArtMonitor, Gothenburg, 2015

Agradecimentos: The authors acknowledge the financial support of the Brazilian agencies FAPESP (05/60119-5, 04/05054-2; 02/03085-2; 02/07536-9), CNPq (308424/2011-5), Millenium Project (42.0222/2005-7), and INCT project (573713/2008-1). Bárbara Lima and Jeane Chaves are thanked for whole-rock Sm-Nd and Sr laboratory facilities at University of Brasilia. We also thank Ignez de Pinho Guimarães and an anonymous reviewer for their valuable comments of the manuscript Abstract: The Sergipano belt is the outcome of collision between the Pernambuco-Alagoas Domain (Massif) and the São Francisco Craton during Neoproterozoic assembly of West Gondwana. Although the understanding of the Sergipano belt evolution has improved significantly, the timing of emplacement, geochemistry and tectonic setting of granitic bodies in the belt is poorly known. We recognized two granite age groups: 630–618 Ma granites in the Canindé, Poço Redondo and Macururé domains, and 590–570 Ma granites in the Macururé metasedimentary domain. U–Pb SHRIMP zircon ages for granites of first age group indicated ages of 631 ± 4 Ma for the Sítios Novos granite, 623 ± 7 Ma for the Poço Redondo granite, 619 ± 3.3 Ma for the Lajedinho monzodiorite, and 618 ± 3 Ma for the Queimada Grande granodiorite. These granitoids are dominantly high-K calc-alkaline, magnesian, metaluminous, mafic enclave-rich (Queimada Grande and Lajedinho), or with abundant inherited zircon grains (Poço Redondo and Sitios Novos). Geochemical and isotope data allow us to propose that Sítios Novos and Poço Redondo granites are product of partial melting of Poço Redondo migmatites. Sr-Nd isotopes of the Queimada Grande granodiorite and Lajedinho monzodiorite suggest that their parental magma may have originated by mixing between a juvenile mafic source and a crustal component that could be the Poço Redondo migmatites or the Macururé metasediments. Other 630–618 Ma granites in the belt are the mafic enclave-rich Coronel João Sá granodiorite and the Camará tonalite in the Macururé sedimentary domain. These granites have similar geochemical and isotopic characteristics as the Lajedinho and Queimada Grande granitoids. We infer for the Camará tonalite and Coronel João Sá granodiorite that their parental magmas have had contributions from mafic lower crust and felsic upper crust, most probably from underthrust São Francisco Craton, or Pernambuco-Alagoas Domain. The younger 590–570 Ma granite group is confined to the Macururé metasedimentary domain. Although these granites do not show typical features of S-type granites, their U–Pb age, field relationships, geochemical and Sr-Nd data suggest that their parental magmas have originated from high degree melting of the Macururé micaschists. Field observations support a model in which the Macururé domain, limited by the Belo Monte-Jeremoabo and São Miguel do Aleixo shear zones, behaved as a ductile channel flow for magma migration and emplacement during the Neoproterozoic, very much like the channel flow model proposed for emplacement of leucogranites in the Himalayas FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado

The age of the Bridgerian/Uintan boundary has been regarded as one of the most important outstanding problems in North American Land Mammal “Age” (NALMA) biochronology. The Bridger Basin in southwestern Wyoming preserves one of the best stratigraphic records of the faunal boundary as well as the preceding Bridgerian NALMA. In this dissertation, I first developed a chronological framework for the Eocene Bridger Formation including the age of the boundary, based on a combination of magnetostratigraphy and U-Pb ID-TIMS geochronology. Within the temporal framework, I attempted at making a regional correlation of the boundary-bearing strata within the western U.S., and also assessed the body size evolution of three representative taxa from the Bridger Basin within the context of Early Eocene Climatic Optimum. Integrating radioisotopic, magnetostratigraphic and astronomical data from the early to middle Eocene, I reviewed various calibration models for the Geological Time Scale and intercalibration of 40Ar/39Ar data among laboratories and against U-Pb data, toward the community goal of achieving a high precision and well integrated Geological Time Scale. In Chapter 2, I present a magnetostratigraphy and U-Pb zircon geochronology of the Bridger Formation from the Bridger Basin in southwestern Wyoming. The ~560 meter composite section spans from the lower Bridger B to the Bridger E, including the Bridgerian/Uintan NALMA boundary in the uppermost part of the section. Analysis of samples from 90 sites indicates two paleomagnetic reversals that are correlated to an interval spanning Chrons C22n, C21r, and C21n by comparison to the Geomagnetic Polarity Time Scale (GPTS). This correlation places the Bridgerian/Uintan faunal boundary within Chron C21n, during the initial cooling phase following the peak of the Early Eocene Climatic Optimum. Based on the bio- and magnetostratigraphic correlation, I provide correlation of other Bridgerian/Uintan boundary-bearing sections to the GPTS, demonstrating that in the western North America, the Bridgerian/Uintan boundary occurs everywhere in Chron C21n. In addition, U-Pb zircon geochronological analyses were performed on three ash beds from the Bridger Formation. High-precision U-Pb dates were combined with the paleomagnetic polarity data of the same ash beds as well as the integrative chronostratigraphy of the basin to assess prior calibration models for the Eocene part of the GPTS. The data from the Bridger Formation indicate that the Option 3 age model of Westerhold et al. (2008) best reconciles the geochronological data from all of the ash beds except for one. Thus I favor this Option 3 model, which indicates the ages of 56.33 Ma and 66.08 Ma for the Paleocene-Eocene Thermal Maximum and Cretaceous/Paleogene boundary, respectively. In Chapter 3, the body size evolution of three mammalian taxa from the Bridgerian NALMA was analyzed within the context of Bergmann’s Rule, which poses a correlation between the size of endotherms and climate (latitude). The Bridgerian NALMA is from a time of global cooling following the peak of the Early Eocene Climatic Optimum, thus according to Bergmann’s Rule, the Bridgerian mammals are expected to increase in size. This hypothesis is tested among Notharctus, Hyopsodus, and Orohippus, using the size of molar dentition as a proxy for their body size. These taxa represent three different ecomorphs, and I investigated if these taxa showed a pattern of body size change consistent with the prediction made by Bergmann’s Rule, and how their ecological adaptation may have affected their response to the climate change. Prior to analyzing the body size evolution, specimens of Notharctus and Hyopsodus were identified to species based on dental characters. This practice differs from previous studies in which species identification relied on relative size of the individuals and stratigraphic levels of origin. Within the new framework of morphologically determined species identification, five species of Notharctus were recognized, among which, N. pugnax, N. robustior and N. sp. indet. exhibited statistically significant body size increase in the time span of interest. Based on morphological analyses of Hyopsodus dentition, I recognized five species. Dentition-based body size analysis showed that H. lepidus and H. despiciens exhibited a statistically significant change towards larger size within the sampled interval. When analyzed at the generic level, a statistically significant increase was observed for both Notharctus and Hyopsodus. Finally, a genus-level analysis of Orohippus showed a lack of statistically significant size increase over the study interval. Thus, among the three taxa from the Bridgerian, Bergmann’s Rule is supported by Notharctus and Hyopsodus, at least at the genus level, but not by Orohippus, although the patterns are more variable at the intraspecific level. In Chapter 4, 40Ar/39Ar dates were obtained from sanidines from the middle Eocene Henrys Fork tuff and Upper Carboniferous Fire Clay tonstein, with the goal of making highly precise measurements of these two samples, keyed to the Fish Canyon monitor standard. Analytically, both samples were well characterized, as had been shown previously. The irradiation disk was arranged such that there would have been control from the Fish Canyon surrounding each of the unknown pits. However, due to several complications in the lab during the course of the experiment, only the analyses from one run disk (Disk 677) were of the quality needed for the goals of the study. As a result, the Fish Canyon sanidine standards that were irradiated near the center of the irradiation disk had to be discarded, and thus, the neutron fluence could not be mapped out precisely across the entire disk. The 40Ar/39Ar age relative to Fish Canyon sanidines is 47.828 ± 0.205 Ma and 311.937 ± 1.282 Ma for the Henrys Fork tuff and Fire Clay tonstein, respectively (1σ, including error on the age of the monitor). Because the ages were both offset about the same amount, I explored the option of using the U-Pb ID-TIMS ages of the Henrys Fork tuff and Fire Clay tonstein to test the agreement in the chronometers. The Henrys Fork tuff was dated at 48.260 ± 0.107 Ma (1σ, including error on the age of the monitor) using the Fire Clay sanidines and assuming its age is the U-Pb zircon age. The Fire Clay tonstein was dated at 314.593 ± 0.699 Ma (1σ, including error on the age of the monitor), using the Henrys Fork sanidines and assuming its age is the U/Pb zircon age. Although the complications encountered render these data unpublishable, they show great promise as the ages of each sanidine sample, tied to the other ash using the other ash’s U-Pb age, give results that are in close agreement between the two chronometers on the same sample (e.g., 314.593 ± 0.699 Ma vs. 314.554 ± 0.020 Ma at 1σ for sanidine and zircon respectively from the Fire Clay tonstein, and 48.260 ± 0.107 Ma vs. 48.265 ± 0.008 Ma 1σ for sanidine and zircon respectively from the Henrys Fork tuff).

The dissemination of the knowledge of critical geological issues, such as past environmental and climate change and their correct placement in the geological time scale, is essential to rise the awareness of the huge potential impact of the Earth Sciences on the current and future generations. We selected two examples (the Marguareis and the Langhe and Monferrato areas) to disseminate these topics to a broad audience. Virtual tours, hosted on the PROGEO-Piemonte project website (www.progeopiemonte.it), have been developed with special care to educational purposes and made suitable for mobile devices. These allow us to overcome theoretical problems related to the complexity of geological items (spatial and evolutionary complexity, deep time dimension), with plain language explanations, detailed pictures and dynamic 3D models. The virtual visit overcomes practical difficulties, such as restricted access to high mountain or dangerous areas, and improves the access to detailed geological information at different scales, not readily available in the outcropping rocks. Dynamic or static information, stored on the website, are available on Google Earth or Google Maps in the field (mobile navigation) or at home (PC-based navigation). The virtual tours thus become an alternative to the visit on site, or a tool for deepening knowledge before or after the visit. This is especially helpful for schools, because virtual tours could be used in classroom with many different goals. The virtual tours, once accessed on-line by many visitors, will in turn push public administrators to realize geotouristic facilities on site and fund educational projects on these important issues.

O Domínio Macururé, localizado na porção norte da Faixa de Dobramentos Sergipana, é caracterizado por apresentar um grande volume de granitos (s.l.) de idade Neoproterozóica. O Maciço Glória Norte (MGN), que ocorre na porção centronorte do Domínio Macururé, representa uma das mais importantes intrusões que se colocaram após o pico de deformação e metamorfismo no orógeno (630 Ma). Nesse estudo identificou-se a presença de duas fácies petrográficas nesse maciço: quartzomonzonítica porfirítica, quartzo-monzonítica, além de diques leucocráticos. Os enclaves de diversos tipos, são uma feição recorrente em toda a extensão do maciço, assim como texturas evidenciam a existência do processo de misturas entre magmas. Os estudos microscópicos permitiram a identificação de várias texturas de instabilidade, e uma sequência de cristalização marcada pelo aumento de fluídos ao longo da evolução do magma. Os dados geoquímicos revelam uma afinidade com as rochas da série shoshonítica e seus enclaves exibem afinidade ultrapotássica com conteúdos de MgO e K2O sempre maiores que 3%. Nos diagramas ETR percebeuse um enriquecimento de ETR leves em relação aos pesados, além de fortes anomalias negativas de Ta, Nb, Ti, P, Sr e Eu, principalmente nos enclaves. As temperaturas médias calculadas pelo geotermômetro de Zr revelam que o início da cristalização no MGN se deu entre 810°C e 784°C e teve seu fim entre 730°C e 700°C. A idade obtida através do método U/Pb SHRIMP (588 + 5,2 Ma) posiciona o magmatismo que deu origem ao MGN, no Período Ediacarano, marcando a ocorrência de um magmatismo a 588 Ma, que não foi afetado por eventos tectônicos. The Domain Macururé located in the northern portion of Sergipano Fold Thrust Belt, is characterized by having a large volume of granites (s.l.) of Neoproterozoic age. The Gloria Norte Massif (GNM), which occurs in the north-central portion of the Domain Macururé, represents a major intrusion that arose after the peak of deformation and metamorphism in the orogen (+ 630 Ma). In this study we identified the presence of two petrographic facies in that massif: quartz-monzonitic porphyritic, quartz-monzonitic and leucocratic dykes. The enclaves, varied tipology, are a recurrent feature in the whole extent of the massif, as well as mixtures of texture of mixing and mingling. Microscopic studies allowed the identification of various textures of the mixing and a sequence of crystallization marked by increased fluids during the evolution of the magma. Geochemical data reveal an affinity with shoshonitic series rocks, and their enclaves exhibit ultrapotassic affinity, wich always show MgO and K2O contents greater than 3%. In the diagrams ETR perceives an enrichment of LREE relative to HREE, and strong negative anomalies of Ta, Nb, Ti, P, Sr, and Eu, mostly in enclaves. The average temperature calculated by Zr geothermometer showed that the onset of MGN crystallization occurred between 810°C and 784°C, and its end was between 730°C and 700°C. The ages obtained by U/Pb SHRIMP (588 + 5.2 Ma) positions the magmatism that gave rise to the MGN, in the Ediacaran and this age mark the occurrence of a magmatism (588 Ma), which was not significantly affected by tectonic events.

El tiempo geológico es un concepto muy complejo en lo que se refiere a la enseñanza y al aprendizaje de las Ciencias de la Tierra, y por eso la necesidad de insistir en el desarrollo de investigación que pueda facilitar su comprensión en el contexto educativo. Este trabajo ha sido realizado en el ámbito del proyecto “El tiempo geológico en contexto escolar: contribuciones de las percepciones de los alumnos para el desarrollo de una alfabetización de los ciudadanos”, de la Universidad de Aveiro (Portugal) y busca diagnosticar las percepciones que los alumnos del 7.º año de escolaridad (12-13 años de edad) tienen sobre este concepto y su papel en la comprensión de la sustentabilidad de la vida en el planeta. Han sido elaborados materiales curriculares, aplicados en clase a alumnos del 7.º y 12.º (17-18 años de edad) años de escolaridad y evaluado su impacto en el aprendizaje. Los resultados encontrados indican que los materiales curriculares producidos han contribuido para una mejor comprensión del concepto de tiempo geológico y han permitido la integración de conocimientos de distintas áreas disciplinares. Este trabajo pretende ser un contributo para mostrar de que forma el concepto de tiempo geológico puede aportar para la educación y la ciudadanía.

Microalgae have significant potential to be an important alternative energy source, but the challenges to the commercialization of bio-oil from microalgae need to be overcome for the potential to be realized. The application of stress can be used to improve bio-oil yields from algae. Nevertheless, the understanding of stress effects is fragmented due to the lack of a suitable, direct quantitative marker for stress. The lack of understanding seems to have limited the development of stress based strategies to improve bio-oil yields, and hence the commercialization of microalgae-based bio-oil. In this study, we have proposed and used the specific intracellular reactive species levels (siROS) particularly hydroxyl and superoxide radical levels, separately, as direct, quantitative, markers for stress, irrespective of the type of stress induced. Although ROS reactions are extremely rapid, the siROS level can be assumed to be at pseudo-steady state compared to the time scales of metabolism, growth and production, and hence they can be effective stress markers at particular time points. Also, the specific intracellular (si-) hydroxyl and superoxide radical levels are easy to measure through fluorimetry. Interestingly, irrespective of the conditions employed in this study, that is, nutrient excess/limitation or different light wavelengths, the cell concentrations are correlated to the siROS levels in an inverse power law fashion. The composite plots of cell concentration (y) and siROS (x) yielded the correlations of y=k1�x-0.7 and y=k2�x-0.79, for si-hydroxyl and si-superoxide radical levels, respectively. The specific intracellular (si-) neutral lipid levels, which determine the bio-oil productivity, are related in a direct power law fashion to the specific hydroxyl radical levels. The composite plot of si-neutral lipid levels (z) and si-hydroxyl radical level (x) yielded a correlation of z=k3�x0.65. More interestingly, a nutrient shift caused a significant change in the sensitivity of neutral lipid accumulation to the si-hydroxyl radical levels. � 2013 Wiley Periodicals, Inc.

M.Sc. The ca. 800 km2 Tete Complex of NW Mozambique is located at the eastern end of the 830 ±30 Ma Zambezi Belt, near the transition zone into the Neoproterozoic Mozambique Belt. The Complex is located just south of the Sanangoe Shear Zone where Mesozoic and Late Palaeozoic cover rocks obscure much of the region. Country rocks immediately in contact with the Tete Complex include amphibolitic gneiss, graphite-bearing marble, calcsilicate gneiss, muscovite and biotite schist and quartzite of the Chidue Group. The Tete Complex may have been intrusive into the Chidue Group, although there is evidence inferring tectonic emplacement. Those few contact exposures that exist are equivocal. Some of the rocks within the Tete Complex have been affected by metamorphism up to amphibolite grade, although large proportions of the rocks retain pristine magmatic mineralogy and texture. The Tete Complex contains mafic, ultramafic and anorthositic rocks, dolerite dykes and minor Fe-Ti oxide-rich rocks that occur as rubble. Pyroxenite occurs as thin (

In this shortnote, we present the results of a geochronological study of the last eruption in the volcanic region of the Garrotxa (NE Iberian Peninsula). Four 14 C analysis of organic matter contained in palaeosols located under volcanic pyroclastic fall deposits of the Croscat volcano were made. The samples gave ages between 13160 and 15710 years cal BP, and are in accord with our palynological analysis and climate reconstruction at that time. The ages that we report are the youngest obtained for volcanic activity in the Iberian Peninsula

Agradecimentos: This work is part of Alencar's PhD research and is financially supported by Brazilian foundation CNPq (grants #141705/2008-6 and #201847/2009-4). The study of projected length annealing of ion tracks was an idea from Dr PJ Iunes (in memoriam). Critical comments from an anonymous reviewer are also acknowledged Abstract: Slices of apatite (cut similar to 45 degrees apart from c-axis) were irradiated with Sm-152 ions and heated at different steps in order to investigate the thermal annealing property of tracks generated by these ions. The ions were impinged with 45 degrees and similar to 150 MeV at apatite surface. Samples were etched with diluted nitric acid. Results of annealed projected lengths are presented for isochronal 10, 100 and 1000 h thermal treatments (runs) for samples with and without pre-annealing preparation. For low annealing temperatures, a distinct behavior of these samples was observed: pre-annealed samples presented a faster annealing rate. At elevated temperatures, the behavior seems to be equal. A single activation energy model was fitted to data and the energy obtained is in agreement with literature. Finally, despite the different trend in comparison with annealing rates of confined fission tracks, extrapolation to geological timescales presents reasonable estimates, indicating small influence of surface effects and, in principle, the possibility to employ ion tracks as proxies for annealing kinetics CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Fechado

The volcanic system of La Reunion is made of the coalescent Piton des Neiges and Piton de la Fournaise edifices. Its formation, associated with the activity of a mantle plume, is characterized by phases of submarine and subaerial growth, followed by a period of destruction, as described in the classical model proposed for Hawaiian Island volcanoes. Previous studies showed that the subaerial activity of La Reunion would have started around 2.2 Ma ago. Geochemical analyses carried out on the products associated with subaerial and submarine volcanism revealed their transitional chemical nature and their peculiar homogeneous isotopic compositions (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) for a hotspot derived magmatism. In this study, we show that some unusual submarine lavas were recently identified below the basal series of Piton de la Fournaise volcano (dredged on the North-East Rift Zone of la Fournaise) and below the subaerial lavas outcropping at the base of the differentiated series of Rivière des Remparts, indicate that the evolution of La Reunion system is probably more complex than previously suggested. The question of the nature and origin of these lavas, together with their implication on the formation of La Reunion, is an issue of major interest in order to better constrain the global evolution of the volcanic system. As a consequence, new petrological, geochemical and geochronological investigations were conducted on the submarine part of La Reunion edifice. They revealed the existence of a geochemically exceptional group of lavas. Its composition is clearly different from common samples of La Reunion and presents (1) an enrichment in incompatible elements and (2) tends toward an enriched EM endmember. These chemical specificities reveal that the source of La Reunion magmatic products is (1) an heterogeneous source affected by (2) variable melting degrees. Moreover, two samples of this new group dated at 3.77 (0,08) and 3.34 (0,07) Ma extend considerably the period of activity of the island. These rocks are the oldest samples ever dated at La Reunion. The nature and stratigraphical location of subaerial and submarine samples from Piton des Neiges and Piton de la Fournaise imply a new interpretation of the global evolution of the island. Unlike previous studies, our results indicate that :(1) The differentiated subaerial lavas from Rivière des Remparts, due to their stratigraphical and geographical location underlying Piton de la Fournaise, and by analogy with the Piton des Neiges, cannot be linked to the activity of Piton de la Fournaise. (2) The isotope signature of the submarine lava group from the North-East Rift Zone of Piton de la Fournaise, reveals the heterogeneous character of the mantle source under La Reunion Island, that can be modelled as embedded eclogite in a matrix of spinel lherzolite, (3) The age of this submarine group and its location under the eastern flank of Piton de la Fournaise, imply a more complex model of evolution of La Reunion. Therefore, our geochemical and geochronological data are new arguments suggesting the existence of a third volcanic center on the island. This assumption confirms the previous petrological and geophysical evidence supporting the existence of this volcano at the East of La Reunion, commonly called Les Alizés volcano.; Le système volcanique de La Réunion est formé de la coalescence des massifs du Piton des Neiges et du Piton de la Fournaise. Son édification, liée à l’activité d’un panache mantellique, est caractérisée par une phase de croissance sous-marine, puis subaérienne, suivie d’une période de dégénérescence, comme proposé classiquement pour les volcans boucliers océaniques d’Hawaii. De précédentes études ont montré que l’activité subaérienne de La Réunion aurait débuté il y a environ 2,2 Ma. Les analyses géochimiques menées jusqu’alors sur les produits associés à cette activité volcanique (subaérienne et sous-marine) ont montré un caractère chimique transitionnel avec une composition isotopique (87Sr/86Sr, 143Nd/144Nd et 176Hf/177Hf) particulièrement homogène pour un volcanisme de point chaud. Dans cette étude, nous montrons que des laves sous-marines récemment identifiées sous la série basique du Piton de la Fournaise (au sein de la sur Rift Zone Nord-Est) ainsi que des laves subaériennes affleurant à la base de canyons incisés dans le massif (Série Différenciée de la Rivière des Remparts), présentent des caractéristiques ne s’inscrivant pas dans le modèle d’évolution proposé précédemment pour ce volcan. Se pose donc la question de la nature et de l’origine de ces laves, ainsi que de leur place et appartenance dans l’édification du système volcanique réunionnais. De nouvelles investigations pétro-géochimiques et géochronologiques ont été menées sur la partie sous-marine de l’édifice de La Réunion. Elles révèlent l’existence d’un groupe de laves exceptionnel. Leur composition se distingue clairement de celle des échantillons communément analysés à La Réunion et montre (1) un enrichissement en éléments incompatibles couplé isotopiquement à (2) un rapprochement vers un pôle mantellique enrichi de type EM. Ces particularités géochimiques démontrent que le panache mantellique possède (1) une source hétérogène affectée par (2) des taux de fusion variables. De plus, deux échantillons de ce nouveau groupe datés à 3,77 (0,08) et à 3,34 (0,07) Ma étendent considérablement la période d’activité connue de l’édifice. Ces âges remarquables font de ces laves les plus anciennes jamais datées à La Réunion. La nature géochimique ainsi que la position stratigraphique des laves de cette étude (échantillons subaériens et sous-marins des massifs du Piton des Neiges et du Piton de la Fournaise) impliquent une réinterprétation du schéma d’évolution global de l’île. Contrairement aux études précédentes, nos résultats sur ces laves montrent que : (1) Les laves différenciées de la Rivière des Remparts, qui sont des laves subaériennes, de part leur position stratigraphique et géographique sous-jacente au Piton de la Fournaise et par analogie avec le Piton des Neiges, ne peuvent être reliées à l’activité de la Fournaise, (2) Le signal isotopique du groupe de laves sous-marines de la Rift Zone Nord-Est de la Fournaise, révèlent l’hétérogénéité de la source du panache mantellique sous La Réunion, source que nous identifions comme des enclaves d’éclogite contenues dans une lherzolite à spinelle, (3) L’âge plus ancien de ces laves sous-marines et leur localisation sous le flanc Est de la Fournaise remet en questions le schéma jusqu’alors admis pour l’édification de l’île de La Réunion reposant sur la construction du Piton des Neiges puis celle, adjacente, du Piton de la Fournaise. En conséquence, nos données géochimiques et géochronologiques sont de nouveaux arguments en faveur de l’élaboration d’un modèle d’évolution plus complexe, suggérant l’existence d’un troisième massif volcanique. Il est en accord avec les précédents travaux de pétrologie et de géophysique suggérant l’existence d’un troisième édifice à l’Est de La Réunion, communément appelé le Volcan des Alizés.

1 CD-ROM : il., mapas, Desde 1.932 se está discutiendo acerca de la estratigrafía y la composición de los depósitos y rocas que constituyen la Formación Popayán, surgiendo varias propuestas estratigráficas que se han venido actualizando de acuerdo a la evolución de los conceptos que, con el transcurrir del tiempo, ha tenido la vulcanología. A partir de la caracterización de los depósitos de la Formación Popayán se plantea que está constituida primordialmente por depósitos de flujos de ignimbritas y por espesos depósitos de flujos de ceniza y bloques de hasta 200 m de espesor que rellenaron un paleorelieve, construido sobre rocas del Paleozoico al Paleoceno, conformando la Meseta de Popayán. Se propone que la sección estratigráfica tipo de la Formación Popayán sea la levantada en la quebrada Sombrerillo, localizada al norte de la Meseta de Popayán en el Municipio de Morales, de muy fácil acceso, y donde está perfectamente representada ésta formación. Las columnas estratigráficas levantadas en la Chorrera del Club Campestre del municipio de Popayán y en la quebrada La Chorrera- río Hondo, al sur de la meseta, en el municipio de El Tambo, se consideran secciones estratigráficas de referencia. En la sección estratigráfica de la quebrada Sombrerillo se observa la base de la Formación Popayán conformada por depósitos de flujos de ignimbritas con un espesor máximo observado de 100 m; estas ignimbritas están suprayacidas por una serie de depósitos de flujos piroclásticos y depósitos vulcano sedimentarios, con un espesor máximo observado de 100 m, sobre los que se desarrolló un paleosuelo de color rojo que se propone constituye el techo de la Formación de Popayán. Los análisis geoquímicos ubican las ignimbritas de la Formación Popayán en las series magmáticas calcoalcalinas, siendo su composición riolítica alta en potasio. Estas características las comparten con las ignimbritas de la Formación Guacacallo ubicadas en el valle geográfico del río Magdalena en el departamento del Huila; las dos formaciones tienen, igualmente, características cartográficas, geomorfológicas y estratigráficas comparables y esto permite su correlación. De acuerdo con los estudios petrográficos realizados, los depósitos de flujos de ceniza y bloques estratigráficamente localizados hacia el techo de las ignimbritas son de composición andesitica. Los volúmenes estimados para las ignimbritas de las formaciones de Popayán y Guacacallo son de aproximadamente 250 Km3, sin considerar los volúmenes de las cenizas acompañantes o co-ignimbritícas, cuyos cálculos pueden ser iguales a los de las ignimbritas propiamente dichas. Estos volúmenes son indicadores de la gran significancia que tiene el vulcanismo riolítico en el segmento volcánico central de la Cordillera Central de Colombia. Así mismo, su volumen y el alto contenido en potasio permite suponer que la génesis de los magmas que generaron los mantos ignimbríticos de las Formaciones de Popayán y Guacacallo está relacionada con la corteza continental. Las ignimbritas denominadas en este trabajo de Pisojé Alto, ubicadas en el piedemonte occidental de la Cordillera Central y que bordean la Meseta de Popayán, de acuerdo con su información geoquímica, son de composición traquiandesitíca-andesitica, altas en potasio y hacen parte de las series calcoalcalinas. Estas ignimbritas, de composición andesitica, no son correlacionables con las de la Formación Popayán y se propone que hacen parte de la Formación Coconuco. De acuerdo a las dataciones de las ignimbritas del suroccidente de Colombia existentes en la literatura, y a las dataciones de 40Ar/Ar39 realizadas en esta investigación, consideradas referentes estratigráficos debido al alto contenido de argón atmosférico, el vulcanismo riolítico alto en potasio, del suroccidente de Colombia, se extiende desde hace 7.1±0.3 M.a hasta 2.1±0.4 M.a y sobre él se está construyendo el vulcanismo reciente., From 1932 there has been discussion of the stratigraphy and composition of deposits and rocks that constitute the formation of Popayán; a number of proposals have emerged in accord with the progressive evolution of concepts in the field of volcanology. The formation of Popayán was constituted of ignimbrites flows, ash deposits and 200 m blocks which filled a paleorelief, constructed between the Paleozoíco and the Paleocene, forming the plateau of Popayán. It is proposed that the typical stratigraphic formation of Popayán is the one which was shaped in the Sombrerillo Creek, located north of the plateau of Popayán in the municipality of Morales, easy access, where this formation is very well represented. The stratigraphic column erected on the Chorrera stream at the Country Club located in the municipality of Popayán and the one on the Hondo River, to the South of the plateau, in the municipality of El Tambo, are considered stratigraphic sections of reference. In the stratigraphic section of the Sombrerillo Gorge, composed of ignimbrites deposits with an observed maximum thickness of 100 m, the base of the Popayán formation can be observer. These ignimbrites are superimposed by a number of pyroclastic deposits and volcanic sediment, with a maximum observed thickness of 100 m, upon which was developed a regional red paleosuelo extension proposed as the roof of the formation of Popayán. Geochemical analyses locate the ignimbrites of the Popayán formation in magmatic calco-alkaline series, with riolitic composition high in potassium. These characteristics are share with the Guacacallo ignimbrites located in the geographic Valley of the Magdalena River in the Department of Huila; these two formations also have comparable cartographic, geomorphologic and stratigraphic features that allow their correlation. According to petrography studies, deposits of ash flow and block stratigraphic located towards the ceiling of the ignimbrites are of andesitic composition. Estimated ignimbrites volumes for the Popayán and Guacacallo formations are approximately 250 Km3, without considering the accompanying ash or co-ignimbrites, which may be calculated as equal to the actual ignimbrites volume. These volumes indicate the significance of riolitic volcanism in the central volcanic segment of the Central Cordillera of Colombia. The total volume and high potassium content allow it to be assumed that the genesis of the magmas that generated the formations of Popayán and Guacacallo ignimbrites mantel is related to the continental crust. The ignimbrites denominated in this work Upper Pisojé, located on the western foothills of the Cordillera Central and bordering the plateau of Popayán, according to their geochemical information are of traquiandesitic-andesitic composition, high in potassium and are part of the calco-alkaline series. These ignimbrites are not correlated with the Popayán formation and it is proposed that they belong to the Coconuco formation. High in potassium, southern Colombian West riolitic volcanism extends from 7. 1± 0. 3 up to 2 M.a. ±0. 4 M.a upon which recent volcanism is being built., 1. Introducción -- 1.1 Objetivos -- 1.2 Localización -- 1.3 Metodología -- 1.4 Alcances y limitaciones -- 2. Estudios Anteriores -- 2.1 Introducción -- 2.2 Ignimbritas -- 2.3 Ignimbritas y estructuras caldéricas en los Andes -- 2.4 Ignimbritas de Colombia -- 2.5 Edad del vulcanismo ignimbrítico en Colombia -- 2.6 Modelos Vulcano-tectónicos propuestos para el emplazamiento de grandes volúmenes de ignimbritas -- 7 Características de la Subducción, composición y aspectos estructurales de la corteza continental en Colombia -- 2.8 Aspectos estructurales relacionados con el vulcanismo de los Andes en general y en Colombia en particular -- 2.9 Unidades litológicas de la zona de estudio -- 2.9.1 Rocas del Complejo Arquía (Pz?ecm) -- 2.9.2 Rocas basálticas, ultrabásicas y los sedimentos asociados de edad mesozoíca -- 2.9.3 Rocas del Grupo del Cauca (Pgech, Pgog, Pgof, Ngme) -- 2.9.4 Intrusivos del Neógeno (Ngi) -- 2.9.5 Formaciones volcano sedimentarias de Neógeno -- 2.9.6 Depósitos de flujos de escombros volcánicos -- 2.9.7 Depósitos aluviales y depósitos de vertiente (Qalca, Qal, Qt, Qv) -- 3. Resultados -- 3.1 Geomorfología -- 3.1.1 Unidad de montañas con laderas largas y rectas (MIlr) -- 3.1.2 Unidad de colinas aisladas (Ca) -- 3.1.3 Unidad de cañones y valles (Crca, Crpa, Ceb, Crpipe; Vrpt, Vrca, Vrh, Vrpa) -- 3.1.4 Unidad bloque de Piendamó (Bpi) -- 3.1.5 Unidad de escarpes (Ess, Esn, EsfPo, Esfpi) -- 3.1.6 Unidad de Colinas de Cimas Redondeadas (Ccr) -- 3.1.7 Unidad de superficies onduladas con control estructural (Soce) -- 3.1.8 Unidad del abanico de escombros volcánicos del río Piendamó (Api) -- 3.1.9 Unidad de colinas de cima plana (Ccp) -- 3.1.10 Unidad de ápices de abanicos sucesivos (Aas) -- 3.1.11 Unidad del abanico de escombros volcánicos de los ríos Blanco y Cofre (Abcof) -- 3.1.12 Unidad del abanico de escombros volcánicos del río Cajibío (Acaj) -- 3.1.13 Unidad del abanico de escombros volcánicos de Calibío (Acab) -- 3.1.14 Unidad del abanico de escombros volcánicos de San Isidro (Asi) -- 3.1.15 Unidad del cono aluvial del río Cauca (Carc) -- 3.1.16 Unidad de llanuras de inundación y terrazas aluviales (LLita) -- 3.2 Caracterización de las secuencias de ignimbritas de la Formación Popayán -- 3.2.1 Geología -- 3.2.2 Estratigrafía de las secuencias ignimbríticas de la Formación Popayán -- 3.2.3 Caracterización petrográfica de las secuencias de ignimbritas -- 3.2.4 Caracterización geoquímica de las ignimbritas -- 3.2.5 Cronología -- 3.2.6 Correlación estratigráfica de las ignimbritas de la Formación Popayán -- 4. Análisis y discusión de los resultados -- 5. Conclusiones -- 6. Recomendaciones -- 7. Referencias -- Lista de Figuras – Lista de tablas – Lista de anexos

M.Sc. The configuration of the supercontinent Rodinia, at the end of the Mesoproterozoic to the beginning of the Neoproterozoic (1100-750 Ma), and its subsequent break up into cratonic fragments that would later result in the formation of Gondwana (Early Palaeozoic), is still not completely understood. This is largely due to ambiguity surrounding relationships between cratons, craton evolution and timing of significant tectonic or sedimentary events. Particular to this study is the evolution and palaeogeographic history of the Kalahari Craton and a comprehensive provenance analysis of Neoproterozoic to early Palaeozoic clastic sedimentary rocks from the Kango Inlier (Saldania Belt, South Africa). This includes the Cango Caves and Kansa Groups as well as the Schoemanspoort and the adjacent Peninsula Formation (Table Mountain Group, Cape Supergroup). A well established lithostratigraphy, in addition to recent establishment of age constraints by UPb zircon dating and microfossil evidence, allowed for strategic sampling with the objective of gaining insight to the crustal evolution of SW Gondwana. In this study, a progression from immature, moderately altered rocks in the Cango Caves Group (Upper Neoproterozoic) to mature, strongly altered rocks in the Lower Palaeozoic Kansa Group and overlying formations is observed. Thus, rapid sedimentation of the former is anticipated, while the subsequent formations developed at a passive/rifted margin culminating in the laterally extensive deposition of the Peninsula Formation. Ongoing extensional movement is evident due to chronologically deeper-water facies and the progressive influence of a less fractionated component in the Cango Caves Group, particularly in the Huis Rivier Formation. The association of these rocks with an active margin is not certain since index trace element concentrations are too high for typical arc terranes. Thus, the mixing of a younger (570-600 Ma) magmatic source (close to an active margin) with mafic and felsic rocks of the older Mesoproterozoic Natal- Namaqua Mobile Belt (NMB) is the most likely possibility. A maximum, pre-Cape Granite age of 571 Ma can be assigned to the Huis Rivier Formation (Cango Caves Group) by detrital zircon dating, and thus correlation with the Malmesbury Group can be made. Ediacaran age zircons might be related to the active continental margin (Trans Antarctic Orogen) surrounding southern Gondwana, but this is still hypothetical. The post-Cape Granite Kansa Group and overlying Schoemanspoort Formation were most likely deposited as basin infill subsequent to folding and transtensional tectonics affecting the underlying Cango Caves Group. The Kansa Group may be comparable with the Klipheuwel Formation (southwest South Africa) in terms of its stratigraphic position beneath the Table Mountain Group. Deposition of the Table Mountain Group is much younger than previously believed in light of Ordovician zircon ages (471, 485, 499 Ma) obtained from the underlying Kansa Group. However, the provenance of these thus far unheard of ages for magmatic events in South Africa is a matter of contention. The proximal Ordovician Ross-Delamerian Orogenic event in Antarctica is the most likely source. Peninsula Formation deposition represents a cover sequence i.e. the culmination of small isolated basins (e.g. the Kansa Group and lower Table Mountain Group) into a larger, laterally extensive basin where reworking played a dominant role. This basin is likely to be a rift-related. However, it is not clear which crustal entity rifted away from vi South Africa and if, during the Ordovician an, active continental margin further to the south - bridging the South American Famatina Orogen with the Ross-Delamerian arc in Antarctica - existed. The Natal-Namaqua Mobile Belt appears to be the predominant source throughout the succession as indicated by Nd-isotope data and zircon populations. This implies that simple crustal recycling of Natal-Namaqua basement (or rocks with similar Nd-isotope characteristics) led to the genesis of the magmatic material younger than 1 Ga, observed in this study.

M.Sc. Please refer to full text to view abstract

M.Sc. The Limpopo Complex (LC) of southern Africa is one of the best-studied Precambrian granulite facies terrains in the world, yet workers still disagree on fundamental aspects of the geological evolution of this complexly deformed high-grade terrain. Most workers agree that the two marginal zones were exhumed in the late-Archaean, but disagree on the timing of major tectono-metamorphic events that affected the Central Zone (CZ) of Limpopo Belt, and the mechanism/s of its formation. There are currently two main schools of thought: The first school regards the LC as a late-Archaean orogenic zone that resulted from a north-south collision of the Zimbabwe and Kaapvaal cratons. Granitic plutons throughout the entire LC are considered to be accurate time-markers for this orogeny. The second school suggests that the CZ evolved as a result of a major Paleoproterozoic tectono-metamorphic event based mainly on the interpretation of metamorphic mineral ages. The present study focuses on two aims, namely (i) to provide a synthesis of published data as a basis to understand the ongoing age controversy concerning the evolution of the CZ, and (ii) to show that specific fold types in the CZ can be related to either the late-Archaean or the Paleoproterozoic event. New age, structural, metamorphic, and petrographic data are presented to show that (i) major sheath folds reflect the peak tectono-metamorphic event that affected the CZ in the late-Archaean, while (ii) major cross folds developed as a result of a transpressive event in the Paleoproterozoic. The age of formation of the Avoca sheath fold located about 40 km west of Alldays is accurately constrained by the age of emplacement of different structural varieties of precursors to the Singelele Gneiss: penetratively deformed syn- to late-tectonic Singelele gneisses with a zircon SHRIMP age of 2651 ± 8 Ma, date the time of formation of the sheath fold that is characterized by a single population of linear elements that define the central fold axis. The Avoca sheath fold documents top-to-the-NNE movement of material during the exhumation of the high-grade CZ rocks. Weakly foliated late-tectonic L-tectonites with a zircon SHRIMP age of 2626.8 ± 5.4 Ma, outcrop near the centre of the sheath fold, and provide a minimum age for the shear deformation event. An almost undeformed (post-tectonic) variety of the Singelele Gneiss was emplaced after the shear event. A detailed metamorphic study of metapelitic gneisses from the large Baklykraal cross fold, located about 20 km east of the Avoca sheath fold, documents a single decompression-cooling (DC) P-T path for the evolution of this structure. Three studied metapelitic samples characterized by a single generation of garnet provide a Pb-Pb age of 2023 ± 11 Ma, that accurately constrain the time of formation of this major fold to the Paleoproterozoic. A metapelitic sample characterized by two generations of garnet provide a slightly older Pb-Pb age of 2173 ± 79 Ma, that is interpreted to also reflect the late-Archaean event. The Baklykraal cross fold is characterized by two populations of linear elements: the one population defines the shallow N-S oriented fold axes, while the second population is associated with top-to-the-NNE movement of material during exhumation, resulting in folds with a nappe-like geometry. A DC P-T path for the Campbell cross fold (Van Kal, 2004) located just west of Musina, suggests that cross folds developed under significantly lower P-T conditions than is the case with sheath folds, providing an explanation for the lack of significant anatexis associated with the Paleoproterozoic event. The late-Archaean orogeny in contrast, was accompanied by widespread anatexis during a major magmatic event that is characterized by an abnormal high radiogenic signature. This study, for the first time, provides evidence that link specific fold types, and thus deformational events, to different tectono-metamorphic events. The main conclusion is that the CZ was exhumed as the result of two distinct orogenies, one in the late-Archaean, and the other in the Paleoproterozoic.

M.Sc. Please refer to full text to view abstract

This study attempts to discern if geologic time is a threshold concept for student understanding of evolutionary theory. A threshold concept enables the learner to unpack other concepts because of its importance in thought construction. In this study three teachers and ten sections of biology were investigated from the same high school. Each teacher used the same activities, in the same sequence, and with identical evaluation methods. Students in the treatment group covered a unit on geologic time prior to completing course work on evolutionary theory. Student misconceptions in both control and treatment groups were assessed using a composite concept inventory administered post and prior to the study. Statistical analysis conducted revealed no statistical evidence to support the contention that the treatment method was more effective than traditional methods of teaching evolution. It was found that students agreed significantly more with evolution post study in both treatment and control groups.

Orientador: Yara Kulaif Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias Resumo: O trabalho relata um estudo de caso envolvendo uma abordagem interdisciplinar de temas geocientíficos em uma disciplina regular de História do III Ciclo - 5º nível do ensino fundamental de uma escola pública. Nele, o professor, atuando também como pesquisador, procurou observar e interpretar, por meio de transcrições de aulas-debates, textos e desenhos produzidos pelos alunos, a construção do conceito de tempo ¿ um conceito-chave e extremamente importante na aproximação entre a disciplina de História e a Geologia. Sendo assim, para este estudo, utilizou-se uma unidade programática daquele nível de ensino, aquela voltada para o conceito de tempo, de modo a enfocar tanto a sua dimensão social e humana, normalmente adotada nesta disciplina, quanto a sua dimensão no tempo geológico. No trabalho com o tempo geológico, a observação e o estudo do entorno da escola, mais especificamente, a Serra dos Cocais (Valinhos, SP, Brasil) foram fundamentais. Duas questões principais nortearam esta pesquisa: Como utilizar a especificidade de paisagens do entorno da escola para a construção de um conceito de tempo estendido até sua dimensão geológica? E, que possibilidades pedagógicas envolvem a abordagem de conceitos típicos das Ciências da Terra para o professor de História do ensino fundamental? Em meio à pesquisa destas possibilidades, optamos por privilegiar a ênfase na elaboração conceitual dos alunos, por meio da mediação do professor/pesquisador no desenvolvimento das atividades, bem como, por evidenciar o relevante papel do entorno, ou seja, do ambiente local, no processo do conhecimento cognitivo das crianças. Assim, entende-se que, ao integrar o conhecimento geológico no estudo da História, propicia-se a compreensão de que o tempo das culturas humanas está contido num tempo ambiental muito mais amplo que não pode ser ignorado pelas ciências sociais Abstract: The work reveals a case study involving an interdisciplinary teaching approach for treating geosciences¿ subjects in a discipline of History of the 'III Ciclo¿ ¿ 5th level of the fundamental education of a public school. In that, the teacher, also acting as researcher, observes and interprets, by means of transcriptions of class-debates, texts and drawings produced by the students, the construction of the concept of time ¿ an extremely important and a key-concept for the confluence of the discipline of History and Geology. For this study, a programmatic unit of that teaching level was used, the one that treats the concept of time, in a way to focus on both its social and human dimension, usually adopted in this discipline, and its dimension in the geologic time. In the work with the geologic time, the observation and study of the surrounding environment of the school, more specifically, the 'Serra dos Cocais¿ (Valinhos, SP, Brazil) were fundamental. Two main questions guided this research: How to use the surrounding landscape of the school in the construction of an extended concept of time covering up to its geological dimension? And, what pedagogic possibilities do involve the typical concepts of the Earth Sciences for teaching History? In searching for these possibilities we opted for privileging the students¿ conceptual elaboration, through the teacher¿s/researcher¿s mediation in the development of the activities, as well as, emphasizing the fundamental role of the surrounding area, that is to say, of the local environment, in the process of the children¿s cognitive knowledge. Thus, integrating the geological knowledge in the History subject provides a better understanding that the time of the human cultures is contained in a much broader natural time that cannot be ignored by the social sciences Mestrado Mestre em Ensino e História de Ciências da Terra

Historical ecologists have demonstrated legacy effects in apparently wild landscapes in Europe, North America, Mesoamerica, Amazonia, Africa and Oceania. People live and farm in archaeological sites today in many parts of the world, but nobody has looked for the legacies of past human occupations in the most dynamic areas in these sites: homegardens. Here we show that the useful flora of modern homegardens is partially a legacy of pre-Columbian occupations in Central Amazonia: the more complex the archaeological context, the more variable the floristic composition of useful native plants in homegardens cultivated there today. Species diversity was 10% higher in homegardens situated in multi-occupational archaeological contexts compared with homegardens situated in single-occupational ones. Species heterogeneity (β-diversity) among archaeological contexts was similar for the whole set of species, but markedly different when only native Amazonian species were included, suggesting the influence of pre-conquest indigenous occupations on current homegarden species composition. Our findings show that the legacy of pre-Columbian occupations is visible in the most dynamic of all agroecosystems, adding another dimension to the human footprint in the Amazonian landscape. © 2015 Lins et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

The second chapter handles the measurement. These are often collected with a Laser Ablation Inductively Coupled Mass Spectrometer (LA-ICP-MS) and the first problem we encountered was the calibration of this instrument. It is used to measure trace elements with an incredibly high spatial resolution. Of course, it has also some major disadvantages. One of these is that the laser, which is used to ablate the solid substrate, has a variable intensity. In addition several other internal instrumental parameters seem to vary over time in an unpredictable manner. Therefore, people use internal standards for more than twenty years. Such internal standards are elements whose concentration does not vary over the sample. Consequently,all variation detected in these internal standards must be due to artificial variation in the instrument. Because the drift of the instrument is reflected in the measurementofthe internal standard, all other concentrationscan be calibratedaccordingto this internal standard. This simple idea seems to work quite well. Unfortunately, the calibration algorithm does not take into account measurement noise in the signal of the internal standards. This is exactly the improvement that we made: imagine two internal standards, each consisting of the same drift pattern, and disturbed by a different noise pattern. A better approximation of the true drift pattern can be reached by the arithmetic mean of both internal standards.Hereinthe drift remains and the noise cancels out. This idea is further refined, so that the uncertainty on the internal standards can be taken into account as well, and an a priori and an a posteriori verification of the model used is given. Further, the myth of mass dependent internal standards is ruled out and finally a real world example is processed. An additional important property of the proposed calibration is that an internal quality check is performed, which warns the investigator if some artefacts or problems occurred during the measurement. The remaining part of this work is devoted to the reconstruction of time series. One of the major problems with data-processing of proxy records (e.g. stable isotope ratios of oxygen or carbon, or trace elements in shells, sponges, corals, sediment cores, etc ) is the dating of individual observations. All these proxy records are measured as function of a distance, while generally the time series are desired. Due to variations and differences in accretion rate, each record has its unique distance series, which cannot be compared with other records or models. Therefore, distance series are transformed into time series. However, this is only possible if additional information about the accretion rate is available. Unfortunately, this is mostly not the case and thus additional assumptions are necessary. Such assumption can be made about the signal and formally written down in the signal model. In addition,the concept of a time base distortion is introduced.As will be shown,this enables us to estimate variations in accretion rate. For this, we started from a previously estimated time base (if this is unknown, we initialize the time base assuming a constant accretion rate). Next, we allow this base to be distorted due to nonlinear accretion rates or hiatuses and we will show how such a distortion can be estimated. In the third chapter, we have illustrated how the time series can be reconstructed, assuming a periodic proxy-record. Therefore, the concept of time base distortions is introduced. First, we propose a model for variations in accretion rate. Next, we illustrate how this accretion rate can be identified and estimated in the Fourier spectrum of the proxy. This approach is compared with the widely used anchor point method in two manners: the assumptions made are compared and next the sensitivity of both methods w.r.t. stochastic noise is illustrated on a simulation. Three case studies are incorporated to validate the method and to illustrate its usef

A new, astronomically calibrated time scale is presented for the Mediterranean Pliocene based on the correlation of sedimentary cycles to astronomical curves which describe the quasi-periodic variations in the Earth's orbit during the last 5.5 Ma. These sedimentary cycles are found in a continuous deep-sea marl sequence emerged above present sea-level due to tectonic uplift. For this sequence, an integrated high-resolution magnetostratigraphy, (planktonic foraminiferal) biostratigraphy and lithostratigraphy is established which underlies the new time scale. This time scale differs substantially from more conventional time scales which rely entirely on K/Ar radiometric dating