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Diagenesis of middle Ordovician rocks from the Lake Simcoe area, south-central OntarioMancini, Laura January 2011 (has links)
Middle Ordovician carbonates in the Lake Simcoe area, south-central Ontario were examined to determine if: (1) The δ18O values of early-stage calcite cement in hardgrounds are useful proxies for Ordovician seawater δ18O values; (2) a regional hydrothermal event affected middle Ordovician strata in the Lake Simcoe area. Whole rock samples of middle Ordovician hardgrounds and immediately overlying limestones containing early calcite cement have δ13C values ranging from -1.7 to +2.9‰ (PDB) and δ18O values ranging from -6.9 to -2.9‰ (PDB). Hardground δ18O values and the similarity of the isotopic composition between the hardgrounds and overlying limestones are consistent with diagenetic alteration during shallow burial, which indicates the hardgrounds are not useful proxies. Late-stage calcite cements have δ13C values from -8.4 to +2.9‰ (PDB) and δ18O values from -11.4 to -6.0‰ (PDB). Late-stage microcrystalline dolomites have δ13C values from -3.9 to +0.4‰ and δ18O values from -10.7 to -7.6‰. Late-stage saddle dolomites have δ13C values from -1.7 to 1.9‰ and δ18O values from -13.8 to -8.5‰. The late-stage carbonate δ18O values are more negative than the early-stage carbonate δ18O values and are interpreted to reflect progressively deeper burial diagenesis.
Four types of fluid inclusions were identified in late-stage calcite, saddle dolomite, barite, and quartz. Type 1 inclusions are aqueous liquid-rich with very consistent low to very low vapour-liquid ratios and are of primary, secondary pseudosecondary and indeterminate origins. Type 2 inclusions are aqueous liquid-only and are of primary and secondary origins. Type 3 inclusions are oil-bearing, liquid-rich with low to medium vapor-liquid ratios and are of secondary origin. Type 4 inclusions are vapour-only and are of indeterminate origin. The type 4 inclusions analyzed did not yield any microthermometric data suggesting they are empty cavities that have lost all their fluid.
Fluid inclusions of primary, secondary and pseudosecondary origins in calcite, dolomite and quartz have overlapping homogenization temperatures ranging from 43 to 188°C. Fluid inclusions of indeterminate origin in calcite and barite have homogenization temperatures from 80 to greater than 200°C. Petrographic and microthermometric evidence indicates that fluid inclusion homogenization temperatures greater than 150°C most likely are caused by stretching or leaking; therefore, are discounted. Fluid inclusion types 1 and 2 represent two fluid inclusion assemblages (FIA) based on final ice melting temperatures. The high salinity (10 to 30 wt%CaCl2) inclusions in FIA 1 are of primary, secondary, pseudosecondary and indeterminate origin in calcite, dolomite, barite and quartz. Fluid inclusions in FIA 1 are interpreted as reflecting saline basin brines from which the host minerals precipitated during burial diagenesis. The low salinity (0 to 2.7 wt%CaCl2) inclusions in FIA 2 are of secondary and indeterminate origin in calcite. Fluid inclusions in FIA 2 may reflect a meteoric origin such as in a vadose or phreatic environment based on inclusions containing different phases and variable vapor-liquid ratios. Alternatively the low salinity inclusions may reflect alteration from an influx of meteoric fluids that migrated through basement faults and fractures during periods of uplift and erosion.
Early and late-stage carbonates from this study precipitated from 18O-depleted pore fluids and/or at progressively higher temperatures accompanying deeper burial. The FIA 1 homogenization temperatures support burial diagenesis at 66 to 80°C if it is assumed the rocks were buried 2 km, the surface temperature was 20°C and the geothermal gradient was between 23 to 30°C/km.
An alternative interpretation is mineral precipitation during a regional hydrothermal event. Burial diagenesis does not explain the fluid inclusion homogenization temperatures of 90°C and greater unless geothermal gradients are higher than 35°C/km or burial depth is increased to 3 km or more. However, thermal maturity of organic matter in the Michigan Basin suggests Ordovician strata were never buried more than 2 km. Four models for regional hydrothermal fluid migration are: (1) gravity-driven flow; (2) ‘squeegee-type’ fluid flow; (3) convection cell fluid flow; and (4) structurally-controlled fluid flow. The gravity-driven model relies on continental heat flow and an influx of meteoric water from basin catchment areas. For the ‘squeegee, convection cell and structurally controlled models, hot fluids could have entered the region from several conduits concurrently during episodic reactivation of basement faults and fracture systems in response to intracratonic stresses created by the continuous interaction of tectonic plates. Determining which of the models best explains regional hydrothermal fluid flow in the Michigan Basin is difficult for several reasons; (1) surface temperatures and maximum burial temperatures at the time of mineral precipitation in the Michigan Basin during the Ordovician are unknown; (2) the timing of mineral precipitation in relation to tectonic pulses is undetermined; (3) there is as yet no known deep-seated heat sources in the Michigan Basin for convection to occur; and (4) it is unknown whether advection is a major process in the Michigan Basin. A collaborative multi-disciplinary research project covering geology, geophysics and hydrogeology would provide much more integrated data than is currently available from stable isotopes, fluid inclusions and organic matter.
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Diagenesis of middle Ordovician rocks from the Lake Simcoe area, south-central OntarioMancini, Laura January 2011 (has links)
Middle Ordovician carbonates in the Lake Simcoe area, south-central Ontario were examined to determine if: (1) The δ18O values of early-stage calcite cement in hardgrounds are useful proxies for Ordovician seawater δ18O values; (2) a regional hydrothermal event affected middle Ordovician strata in the Lake Simcoe area. Whole rock samples of middle Ordovician hardgrounds and immediately overlying limestones containing early calcite cement have δ13C values ranging from -1.7 to +2.9‰ (PDB) and δ18O values ranging from -6.9 to -2.9‰ (PDB). Hardground δ18O values and the similarity of the isotopic composition between the hardgrounds and overlying limestones are consistent with diagenetic alteration during shallow burial, which indicates the hardgrounds are not useful proxies. Late-stage calcite cements have δ13C values from -8.4 to +2.9‰ (PDB) and δ18O values from -11.4 to -6.0‰ (PDB). Late-stage microcrystalline dolomites have δ13C values from -3.9 to +0.4‰ and δ18O values from -10.7 to -7.6‰. Late-stage saddle dolomites have δ13C values from -1.7 to 1.9‰ and δ18O values from -13.8 to -8.5‰. The late-stage carbonate δ18O values are more negative than the early-stage carbonate δ18O values and are interpreted to reflect progressively deeper burial diagenesis.
Four types of fluid inclusions were identified in late-stage calcite, saddle dolomite, barite, and quartz. Type 1 inclusions are aqueous liquid-rich with very consistent low to very low vapour-liquid ratios and are of primary, secondary pseudosecondary and indeterminate origins. Type 2 inclusions are aqueous liquid-only and are of primary and secondary origins. Type 3 inclusions are oil-bearing, liquid-rich with low to medium vapor-liquid ratios and are of secondary origin. Type 4 inclusions are vapour-only and are of indeterminate origin. The type 4 inclusions analyzed did not yield any microthermometric data suggesting they are empty cavities that have lost all their fluid.
Fluid inclusions of primary, secondary and pseudosecondary origins in calcite, dolomite and quartz have overlapping homogenization temperatures ranging from 43 to 188°C. Fluid inclusions of indeterminate origin in calcite and barite have homogenization temperatures from 80 to greater than 200°C. Petrographic and microthermometric evidence indicates that fluid inclusion homogenization temperatures greater than 150°C most likely are caused by stretching or leaking; therefore, are discounted. Fluid inclusion types 1 and 2 represent two fluid inclusion assemblages (FIA) based on final ice melting temperatures. The high salinity (10 to 30 wt%CaCl2) inclusions in FIA 1 are of primary, secondary, pseudosecondary and indeterminate origin in calcite, dolomite, barite and quartz. Fluid inclusions in FIA 1 are interpreted as reflecting saline basin brines from which the host minerals precipitated during burial diagenesis. The low salinity (0 to 2.7 wt%CaCl2) inclusions in FIA 2 are of secondary and indeterminate origin in calcite. Fluid inclusions in FIA 2 may reflect a meteoric origin such as in a vadose or phreatic environment based on inclusions containing different phases and variable vapor-liquid ratios. Alternatively the low salinity inclusions may reflect alteration from an influx of meteoric fluids that migrated through basement faults and fractures during periods of uplift and erosion.
Early and late-stage carbonates from this study precipitated from 18O-depleted pore fluids and/or at progressively higher temperatures accompanying deeper burial. The FIA 1 homogenization temperatures support burial diagenesis at 66 to 80°C if it is assumed the rocks were buried 2 km, the surface temperature was 20°C and the geothermal gradient was between 23 to 30°C/km.
An alternative interpretation is mineral precipitation during a regional hydrothermal event. Burial diagenesis does not explain the fluid inclusion homogenization temperatures of 90°C and greater unless geothermal gradients are higher than 35°C/km or burial depth is increased to 3 km or more. However, thermal maturity of organic matter in the Michigan Basin suggests Ordovician strata were never buried more than 2 km. Four models for regional hydrothermal fluid migration are: (1) gravity-driven flow; (2) ‘squeegee-type’ fluid flow; (3) convection cell fluid flow; and (4) structurally-controlled fluid flow. The gravity-driven model relies on continental heat flow and an influx of meteoric water from basin catchment areas. For the ‘squeegee, convection cell and structurally controlled models, hot fluids could have entered the region from several conduits concurrently during episodic reactivation of basement faults and fracture systems in response to intracratonic stresses created by the continuous interaction of tectonic plates. Determining which of the models best explains regional hydrothermal fluid flow in the Michigan Basin is difficult for several reasons; (1) surface temperatures and maximum burial temperatures at the time of mineral precipitation in the Michigan Basin during the Ordovician are unknown; (2) the timing of mineral precipitation in relation to tectonic pulses is undetermined; (3) there is as yet no known deep-seated heat sources in the Michigan Basin for convection to occur; and (4) it is unknown whether advection is a major process in the Michigan Basin. A collaborative multi-disciplinary research project covering geology, geophysics and hydrogeology would provide much more integrated data than is currently available from stable isotopes, fluid inclusions and organic matter.
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A Chronological Estimation of the Ceremonial Center of Campanayuq Rumi, Ayacucho / Una aproximación cronológica del centro ceremonial de Campanayuq Rumi, AyacuchoMatsumoto, Yuichi, Cavero, Yuri 10 April 2018 (has links)
The main objective of this paper is to construct a site chronology of the Campanayuq Rumi site which is a large ceremonial center of the Formative Period located in the Peruvian south-central highlands. For this purpose, 12 radiocarbon dates obtained from our excavations will be considered in combination with the data of both architectural and ceramic sequences of the site. Through the comprehensive interpretation of these data, we will present a new site chronology of the Campanayuq Rumi site. / El objetivo principal de este artículo es la construcción de la cronología del sitio arqueológico de Campanayuq Rumi, un gran centro ceremonial del Periodo Formativo ubicado en la sierra centro-sur del Perú. Para ello se tomó como base 12 fechados radiocarbónicos obtenidos de las excavaciones de los autores en combinación con los datos de las secuencias arquitectónica y cerámica. Mediante una interpretación integral, se pretende presentar una nueva cronología para este complejo.
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Cronología y conexiones: evidencias precerámicas de AsanaAldenderfer, Mark 10 April 2018 (has links)
Chronology and Connections: Preceramic Evidences at Asana SiteWith its long and continuous history of occupation, the site of Asana has a unique body of information to offer for the study of the Archaic Period in the south-central Andes. In this paper, I explore two important themes: the chronological sequence of occupation at the site with specific regard to the ways in which phases are defined, and the evidence from the site that describes the connections Asana had throughout its occupation with other regions of the Andean world. In the latter I examine in detail projectile point style and the sources of obsidian and other lithic materials found at the site. There is strong evidence for connections to the central Andes, the Colca valley, and the northern Chilean valleys. / Con su larga y continua historia de ocupación, el sitio de Asana tiene un único conjunto de información que ofrecer para el estudio del Periodo Arcaico en los Andes surcentrales. En este artículo, exploraremos dos temas importantes: la secuencia cronológica de la ocupación en el sitio con énfasis en los modos en que se definen las fases y la evidencia que describe las conexiones que Asana tuvo a través de sus ocupaciones con otras regiones del mundo andino. Por último se examinan en detalle los estilos de puntas de proyectil y las fuentes de obsidiana, así como otros materiales líticos encontrados en el sitio. Hay una fuerte evidencia para conexiones con los Andes Centrales, el valle del Colca y los valles del norte chileno.
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Kilómetro 4 y la ocupación del Periodo Arcaico en el área de Ilo, al sur del PerúWise, Karen 10 April 2018 (has links)
Kilometer 4 and the Archaic Period Occupation of the Ilo Area of Southern PerúMore than a decade of research on a series of Archaic Period (roughly 10,000-3000 BP) sites in the Ilo area of southern Peru have yielded enough data on this previously unknown area to outline the long term patterns of development of the Preceramic cultures of this section of the south-central Andean coast. Research at several sites, most notably the Kilometer 4 site, provides evidence of a long and intensive occupation of the region characterized by increasing sedentism and increasingly intensive maritime subsistence through time. During the Early Archaic and Middle Archaic periods, coastal settlements were small, seasonally occupied sites characterized by a mixed subsistence base. By the Late Archaic period, settlement size increased, architecture became more substantial and segregation of different areas within the site increased as the exploitation of coastal resources increased. Archaic period mortuary patterns in the region are clearly associated with those of coastal northern Chile, and preliminary data indicate that Chinchorro mortuary practices prevailed during the Middle Archaic period while Quiani style patterns emerged during the Late Archaic period. / Más de una década de investigaciones en una serie de sitios del Periodo Arcaico (entre 10.000 y 3000 a.p.) en el area de Ilo, al sur del Perú, han proveído datos significativos para esta área antes desconocida a fin de delinear los patrones a largo plazo del desarrollo de las culturas precerámicas de esta sección de la costa de los Andes centro-sur. Los estudios realizados en varios sitios, principalmente en Kilómetro 4, han producido evidencias de una larga e intensiva ocupación en la región, caracterizada por un incremento del sedentarismo y de la subsistencia marítima a través del tiempo. Durante los periodos Arcaico Temprano y Arcaico Medio, los asentamientos de la costa fueron sitios pequeños, ocupados estacionalmente y se caracterizaban por una base de subsistencia mixta. Hacia el Periodo Arcaico Tardío se incrementó el tamaño de los asentamientos y la segregación de diferentes áreas dentro de los mismos; la arquitectura comenzó a ser más sustancial y se intensificó la explotación de los recursos costeros. Los patrones funerarios en la región están claramente asociados con los de la costa norte de Chile, y los datos preliminares indican que las prácticas funerarias Chinchorro prevalecieron durante el Periodo Arcaico Medio, mientras que los patrones estilísticos Quiani emergieron durante el Periodo Arcaico Tardío.
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Morro 1-5 (Arica). Momias y sociedades complejas del Arcaico de los Andes CentralesGuillén, Sonia E. 10 April 2018 (has links)
Morro 1-5 (Arica). Mummies and Complex Societies in South Central AndesThe comparative study of a series of 17 mummies from the Morro 1-5 site in Arica, Chile, is used to discuss the adaptation of the Chinchorro culture of the Archaic period in the South Central Andes. Issues related to the origin and distribution of cultural traits such as artificial mummification and its tipology of forms, as well as biological aspects such as craniometric and epigenetic traits, are íntegrated in the presentation of one of the oldest, most efficient and complex adaptations to the fragile environment of the desertic coast of the South Central Andes. / A partir del estudio comparativo de una serie de 17 momias del sitio Morro 1-5 de Arica, Chile, se discute la adaptación de la cultura Chinchorro del Periodo Arcaico en los Andes Sur Centrales. Aspectos referentes al origen y la distribución de rasgos culturales como el uso de la momificación artificial y su tipología de formas, y biológicos como rasgos epigenéticos y craniométricos, se integran a la presentación de uno de los procesos más antiguos, eficientes y complejos en uno de los ambientes más frágiles del desierto costeño de los Andes Sur Centrales.
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Ambaricho and Shonkolla. From Local Independent Church to the Evangelical Mainstream in Ethiopia. The Origins of the Mekane Yesus Church in Kambata Hadiya.Grenstedt, Staffan January 2000 (has links)
<p>This thesis is a contribution to the scholarly debate on how African Independent Churches (AICs) relate to outside partners. It is a case study from the perspective of the periphery of Ethiopia, which explains the origins of the Mekane Yesus Church in Kambata Hadiya</p><p>The diachronic structure of the study with a focus from 1944 to 1975 highlights how a group of Christians reacted to cultural pressure and formed a local independent church, the Kambata Evangelical Church 2 (KEC-2). The KEC-2 established relations with external partners, like a neighbouring mainstream conference of churches, a neighbouring mainstream church, an international organisation, and a mainstream overseas church and its mission. These relations influenced the KEC-2 to develop into a synod of the Ethiopian Evangelical Church Mekane Yesus (EECMY). The diachronic approach is augmented by synchronic structural analyses, illustrating how aspects in the independent KEC-2, like polity, worship, doctrine and ethos were changing.</p><p>The study contends that "Ethiopian Evangelical Solidarity" was a crucial factor in the development of the independent KEC-2 into a synod of the EECMY. As this factor helped the Ethiopians to transcend barriers of ethnicity, social status and denominationalism, it is not unreasonable to assume that the study has relevance for a wider African context.</p><p>This thesis builds on material taken mainly from unpublished printed sources in various languages from archives in Ethiopia, Finland, Sweden, Switzerland and the USA. These are supplemented by interviews made by the author.</p>
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The Political Economy of Environmental Justice: A Comparative Study of New Delhi and Los AngelesAsokan, Ratik 01 January 2015 (has links)
Though mainstream environmentalism, both in the U.S. and India, was initially rooted in social justice, it has, over time, moved away from this focus. The Environmental Justice Movement consequently arose to reunite social and environmental activism. In this thesis, I trace the historical relationship between the mainstream environmentalism, the Environmental Justice Movement, and marginalized communities. After providing this general overview, I examine two case studies – in Los Angeles and New Delhi respectively – where marginalized communities have been involved in Environmental Justice activities. My analysis reveals that marginalized communities often act in an ‘environmentalist’ or ‘environmentally friendly’ manner, without defining their actions as such. That is, their socio-political activism often is or becomes environmental because of the contexts it operates within.
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Ambaricho and Shonkolla. From Local Independent Church to the Evangelical Mainstream in Ethiopia. The Origins of the Mekane Yesus Church in Kambata Hadiya.Grenstedt, Staffan January 2000 (has links)
This thesis is a contribution to the scholarly debate on how African Independent Churches (AICs) relate to outside partners. It is a case study from the perspective of the periphery of Ethiopia, which explains the origins of the Mekane Yesus Church in Kambata Hadiya The diachronic structure of the study with a focus from 1944 to 1975 highlights how a group of Christians reacted to cultural pressure and formed a local independent church, the Kambata Evangelical Church 2 (KEC-2). The KEC-2 established relations with external partners, like a neighbouring mainstream conference of churches, a neighbouring mainstream church, an international organisation, and a mainstream overseas church and its mission. These relations influenced the KEC-2 to develop into a synod of the Ethiopian Evangelical Church Mekane Yesus (EECMY). The diachronic approach is augmented by synchronic structural analyses, illustrating how aspects in the independent KEC-2, like polity, worship, doctrine and ethos were changing. The study contends that "Ethiopian Evangelical Solidarity" was a crucial factor in the development of the independent KEC-2 into a synod of the EECMY. As this factor helped the Ethiopians to transcend barriers of ethnicity, social status and denominationalism, it is not unreasonable to assume that the study has relevance for a wider African context. This thesis builds on material taken mainly from unpublished printed sources in various languages from archives in Ethiopia, Finland, Sweden, Switzerland and the USA. These are supplemented by interviews made by the author.
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Vers une redéfinition de la nature américaine : trois études de cas dans la région de Los Angeles / Towards a Redefinition of Nature in the United States : three Case Studies in the Los Angeles AreaSchmutz, Hélène 08 November 2013 (has links)
Les historiens de l’environnement s’attachent à déchiffrer les modes de relation entre l’homme et la nature aux Etats-Unis. La manière dont elle est définie conditionne les politiques environnementales, et donc contribue à la transformation matérielle du continent. Cinq traditions de la pensée environnementale américaine sont décrites : la nature comme ressource transformée par le travail ; le préservationnisme ; le conservationnisme ; l’écologie ; et la justice environnementale. Ces idées perdurent au XXIème siècle dans les discours construits au sujet de la nature : elles se juxtaposent ou se confrontent. L’objectif de ce travail est de savoir si elles se transforment, en évoluant vers une définition de la relation homme/nature comme hybride socionaturel. À cette fin, trois cas sont étudiés, tous situés dans la région de Los Angeles au début des années 2000. Le premier concerne le ranch Tejon, dont l’accord passé en 2008 entre associations de protection de la nature et propriétaires pose la question du sens donné à une préservation qui veut prendre en compte les aspects à la fois écologiques, mythiques et économiques de ce territoire, vestige du passé de l’Ouest. Le second se rapporte à la décision prise en 2007 par la ville de Los Angeles de revitaliser son fleuve et fournit un exemple de l’élargissement de la définition de la nature : celle-ci peut être urbaine. Enfin, troisième cas, la justice environnementale appliquée à la ferme communautaire de South Central Los Angeles, entretenue de 1994 à 2006, est signe de la transition de la pensée de la nature américaine d’un objet délimité dans l’espace vers une problématique mondiale. / Environmental historians have worked at redefining the modes of relationship between man and nature in the United States. The way this relation is defined conditions environmental politics, and therefore contributes to the material transformation of the continent. Five major trends of thought about nature are described: nature as a resource transformed by work ; preservationism ; conservationism ; ecology ; and environmental justice. Those ideas endure to this very day in the discourses constructed about nature: they either juxtapose or confront each other. The goal of this thesis is to understand whether they undergo a transformation, evolving towards a definition of the man/nature relationship as a socionatural hybrid. To this end, three cases are examined here, all of which are connected with the Los Angeles area in the early 2000s. The first concerns Tejon Ranch and the agreement passed in 2008 about Tejon Ranch between environmental associations and the owners : it poses the question of the meaning given to a preservation that would incorporate ecological, mythical and economic aspects of that territory, a remain of the Western past. The second deals with the decision that was made in 2007 by the City of Los Angeles to revitalize its river and offers a good example of the broadening of the definition of nature: it can also be urban. The ecological and cultural preoccupations about the river complicate the conservation problematic in Southern California. Finally, South Central Farm’s environmental justice case (1994-2006) is the sign of a transition in American environmental ideas from a clearly spatially limited object to a world issue.
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