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Sample records for craton sao francisco

  1. Petrological and Sr-Nd evidence bearing on Early Proterozoic magmatic events of the subcontinental mantle: Sao Francisco craton (Uaua, NE-Brazil)

    NASA Astrophysics Data System (ADS)

    Bellieni, G.; Piccirillo, E. M.; Petrini, R.; Girardi, V. A. V.; Leal, A. B. Menezes; Teixeira, W.; Leal, L. R. Bastos; Min, A. De; Chiaramonti, P. Comin; de Oliveira, M. A. F. Tanner

    1995-12-01

    : Early Proterozoic (2.0 2.4 Ga), unmetamorphosed mafic dykes intrude Archean (3.1 2.7 Ga) terrains of the northern Sao Francisco craton (Uaua, NE-Brazil). The dykes are composed of evolved [atomic Mg/(Mg+Fe2)<0.6] two-pyroxene quartz tholeiites, the compositional variations of which are compatible with gabbro fractionation from different parental melts. The incompatible trace-element patterns indicate that the parental melts derived from partial melting of chemically heterogeneous garnet peridotite sources. Geochemistry and Sr-Nd isotopes imply some contamination of the Uaua dyke magma by continental crustal components during emplacement. Sr-isotopes suggest that the “uncontaminated” dykes may be related to time-integrated depleted mantle materials, while Nd-isotopes suggest mantle sources similar to the bulk Earth composition. The “uncontaminated” dykes have a positive Nb-anomaly and incompatible element contents which do not support appreciable enrichment of large ion lithophile and light rare earth elements in the source(s) throughmantle metasomatism and/or crustal components related to dehydration of a subducting slab, and an anorogenic ensialic emplacement is inferred. The Uaua dykes are chemically and isotopically distinct from the Early Middle Proterozoic (1.9 1.7 Ga) unmetamorphosed dykes from W-Uruguay (Rio de La Plata craton) which are believed to have originated from different garnet peridotite sources. This suggests that Uaua Uruguay compositional differences may reflect different Archean mantle differentiation and evolution of the cratonization processes. If this possibility proves to be correct, then magma genesis from various South American cratons would be by independent cratonic processes and their imprints on the subcratonic mantle.

  2. Agriculture, Rio Sao Francisco, Brazil, South America

    NASA Image and Video Library

    1988-10-03

    The large field patterns in this view of the Rio Sao Francisco basin, Brazil, South America, (11.5S, 43.5W) indicate a commercial agriculture venture; family subsistence farms are much smaller and laid out in different patterns. Land clearing in Brazil has increased at an alarming rate in recent years and preliminary estimates suggest a 25 to 30% increase in deforestation since 1984. The long term impact on the ecological processes are still unknown.

  3. Agriculture, Rio Sao Francisco, Brazil, South America

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The large field patterns in this view of the Rio Sao Francisco basin, Brazil, South America, (11.5S, 43.5W) indicate a commercial agriculture venture; family subsistence farms are much smaller and laid out in different patterns. Land clearing in Brazil has increased at an alarming rate in recent years and preliminary estimates suggest a 25 to 30% increase in deforestation since 1984. The long term impact on the ecological processes are still unknown.

  4. Radar image of Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This radar image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The area is predominantly scrub forest. Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. Image brightness differences in this image are caused by differences in vegetation type and density. Tributaries of the Sao Francisco are visible in the upper right. The Sao Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

    This radar image was obtained by the Shuttle Radar Topography Mission as part of its mission to map the Earth's topography. The image was acquired by just one of SRTM's two antennas, and consequently does not show topographic data but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover, and urbanization.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

  5. Radar image of Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This radar image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The area is predominantly scrub forest. Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. Image brightness differences in this image are caused by differences in vegetation type and density. Tributaries of the Sao Francisco are visible in the upper right. The Sao Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

    This radar image was obtained by the Shuttle Radar Topography Mission as part of its mission to map the Earth's topography. The image was acquired by just one of SRTM's two antennas, and consequently does not show topographic data but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover, and urbanization.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

  6. Shaded Relief of Rio Sao Francisco, Brazil

    NASA Image and Video Library

    2000-02-14

    This topographic image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The scrub forest terrain shows relief of about 400 meters (1300 feet). Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. This region has little topographic relief, but even subtle changes in topography have far-reaching effects on regional ecosystems. The image covers an area of 57 km x 79 km and represents one quarter of the 225 km SRTM swath. Colors range from dark blue at water level to white and brown at hill tops. The terrain features that are clearly visible in this image include tributaries of the Sao Francisco, the dark-blue branch-like features visible from top right to bottom left, and on the left edge of the image, and hills rising up from the valley floor. The San Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems. This shaded relief image was generated using topographic data from the Shuttle Radar Topography Mission. A computer-generated artificial light source illuminates the elevation data to produce a pattern of light and shadows. Slopes facing the light appear bright, while those facing away are shaded. On flatter surfaces, the pattern of light and shadows can reveal subtle features in the terrain. Shaded relief maps are commonly used in applications such as geologic mapping and land use planning. http://photojournal.jpl.nasa.gov/catalog/PIA02700

  7. Shaded Relief of Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This topographic image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The scrub forest terrain shows relief of about 400 meters (1300 feet). Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. This region has little topographic relief, but even subtle changes in topography have far-reaching effects on regional ecosystems. The image covers an area of 57 km x 79 km and represents one quarter of the 225 km SRTM swath. Colors range from dark blue at water level to white and brown at hill tops. The terrain features that are clearly visible in this image include tributaries of the Sao Francisco, the dark-blue branch-like features visible from top right to bottom left, and on the left edge of the image, and hills rising up from the valley floor. The San Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

    This shaded relief image was generated using topographic data from the Shuttle Radar Topography Mission. A computer-generated artificial light source illuminates the elevation data to produce a pattern of light and shadows. Slopes facing the light appear bright, while those facing away are shaded. On flatter surfaces, the pattern of light and shadows can reveal subtle features in the terrain. Shaded relief maps are commonly used in applications such as geologic mapping and land use planning.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter

  8. Shaded Relief of Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This topographic image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The scrub forest terrain shows relief of about 400 meters (1300 feet). Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. This region has little topographic relief, but even subtle changes in topography have far-reaching effects on regional ecosystems. The image covers an area of 57 km x 79 km and represents one quarter of the 225 km SRTM swath. Colors range from dark blue at water level to white and brown at hill tops. The terrain features that are clearly visible in this image include tributaries of the Sao Francisco, the dark-blue branch-like features visible from top right to bottom left, and on the left edge of the image, and hills rising up from the valley floor. The San Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

    This shaded relief image was generated using topographic data from the Shuttle Radar Topography Mission. A computer-generated artificial light source illuminates the elevation data to produce a pattern of light and shadows. Slopes facing the light appear bright, while those facing away are shaded. On flatter surfaces, the pattern of light and shadows can reveal subtle features in the terrain. Shaded relief maps are commonly used in applications such as geologic mapping and land use planning.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter

  9. Agricultural and Ranching area, Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This agricultural and Ranching area, Rio Sao Francisco, Brazil (13.0S, 43.5W) has been under study for several years. See scene STS-31-92-045 for comparison. This area has many small single family subsistence farms, large square and rectangular commercial farms and pastures for livestock grazing. Over the several years of observation, the number and size of farms has increased and center-pivot, swing-arm irrigation systems have been installed.

  10. Agricultural and Ranching area, Rio Sao Francisco, Brazil

    NASA Image and Video Library

    1990-12-10

    STS035-73-082 (2-10 Dec 1990) --- This agricultural and ranching area, Rio Sao Francisco, Brazil (13.0S, 43.5W) has been under study for several years. See scene STS-31-92-045 for comparison. This area has many small single family subsistence farms, large square and rectangular commercial farms and pastures for livestock grazing. Over the several years of observation, the number and size of farms has increased and center-pivot, swing-arm irrigation systems have been installed.

  11. Geotectonic setting and metallogeny of the northern São Francisco craton, Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    Teixeira, João Batista Guimarães; da Silva, Maria da Glória; Misi, Aroldo; Cruz, Simone Cerqueira Pereira; da Silva Sá, José Haroldo

    2010-11-01

    This paper aims at establishing a tectonic and temporal framework to characterize the metallogenic processes that contributed to the origin of the mineral provinces in the northern São Francisco Craton. Many Archean mineralizations (eg. massive sulfide zinc, lead, zinc and copper, besides magnesite-talc, iron-titanium-vanadium, iron, chromite and manganese) were generated before the assembly of the Craton. Deposits of chromite, nickel, gold and emerald were produced during the Paleoproterozoic orogenic cycle, when the Craton was amalgamated into the Atlantica paleocontinent. An extension event is recorded in the Neoproterozoic, during the breakup of Rodinia, associated with deposits of phosphorite and uranium. Kimberlite diamond and gold mineralization were generated during the Brasiliano orogenic cycle, coeval with the amalgamation of West Gondwana. A long-lasting and rather uniform crustal stress is recorded in the area during the Cambrian period. Resetting of the isotopic and magnetic systems that affected the Neoproterozoic sediments of the Irecê Basin at about 520 Ma was attributed to the regional-scale fluid migration and mineralization in the aftermath of the Brasiliano orogenic cycle.

  12. Petrology of Teofilândia granitoids: An example of 2.1 Ga crustal accretion in the São Francisco Craton (Bahia, Brazil)

    NASA Astrophysics Data System (ADS)

    Nascimento, H. S.; Nédélec, Anne; Bouchez, Jean-Luc

    2017-07-01

    Teofilândia granitoids are representative of the Paleoproterozoic plutonic rocks, which intruded the Serrinha block, an Archean crustal fragment of the Sao Francisco Craton (Bahia, Brazil). Three plutons were emplaced, the Teofilândia granodiorite, the Barrocas trondhjemite and the Santa Rosa granite, respectively dated at 2130, 2127 and 2073 Ma. The two first plutons are calc-alkaline rocks following a trondhjemitic trend. They resemble Archean TTGs (tonalites-trondhjemites-granodiorites) by their major and trace element compositions and especially by their fractionated REE patterns, with very low HREE contents. These juvenile magmas resulted from partial melting of a young mafic protolith, likely represented by the nearby Rio Itapicuru greenstone belt. Barrocas trondhjemite and Teofilândia granodiorite derive from similar sources, possibly at different depths and with a different degree of melting. The rocks were deformed at high temperature during the Trans-Amazonian collision and are therefore pre-collisional and ascribed to a subduction stage. The younger Santa Rosa pluton is a small, syn-to post-collisional granite that derived from anatexis of the Archean crust. It is representative of a second, volumetrically minor, plutonic episode of potassic, shoshonitic or alkaline affinities. The large amount of 2.1 Ga granitoids emplaced in Brazil as well as in the West African craton, suggests that, at that time, a global event of possible mantle origin was responsible for the intense magmatic activity that involved both crustal accretion and crustal reworking in many places of the world.

  13. Genesis and geodynamic significance of Mesoproterozoic and Early Cretaceous tholeiitic dyke swarms from the São Francisco craton (Brazil)

    NASA Astrophysics Data System (ADS)

    Rosset, A.; De Min, A.; Marques, L. S.; Macambira, M. J. B.; Ernesto, M.; Renne, P. R.; Piccirillo, E. M.

    2007-06-01

    The eastern border of the São Francisco craton is characterized by widespread Mesoproterozoic (˜1.0 Ga) tholeiitic dykes and minor analogues of Early Cretaceous age (˜130 Ma). The Mesoproterozoic dykes (Salvador, Olivença, Espinhaço, Diamantina) show large elemental and Sr-Nd isotopic variations that suggest different parental melts related to a small-scale heterogeneous mantle of depleted residua and enriched components (Statistical Upper Mantle Assemblage, SUMA), responsible for plume- and crust-type signatures. The Mesoproterozoic intrusions, compatible with early stages of Rodinia breakup, may represent the initial breakup of the São Francisco-Congo junction. Early Cretaceous dykes (Espinhaço) reveal normal and reversed polarities, indicating two distinct intrusive periods. These intrusions have elemental and Sr-Nd isotopic compositions similar to those of the coeval (˜132 Ma) high-TiO 2 tholeiites from southern Paraná Basin (Urubicí-type, Brazil) and northern Etendeka (Khumib-type, Namibia). The genesis of these tholeiites requires lithospheric mantle components, as represented by K-alkaline (and carbonatitic) rocks from the Asuncion-Sapucai graben (Paraguay), that highlight the intriguing Pb-isotope relationships involving the Urubicí-Khumib tholeiites. The essential role of the Tristan plume is difficult to determine. The spatial distribution of such uncommon high-TiO 2 tholeiites reveals that similar lithospheric components may exist in different cratonic blocks and associated mobile belts.

  14. Lutzomyia longipalpis s.l. in Brazil and the impact of the Sao Francisco River in the speciation of this sand fly vector

    PubMed Central

    2008-01-01

    In our recently published article "Lutzomyia longipalpis s.l. in Brazil and the impact of the Sao Francisco River in the speciation of this sand fly vector" by Iliano V. Coutinho-Abreu et al. a sentence located in paragraph 8 in the Discussion section had its meaning altered due to the improper insertion of three words. PMID:18834535

  15. Lutzomyia longipalpis s.l. in Brazil and the impact of the Sao Francisco River in the speciation of this sand fly vector.

    PubMed

    Coutinho-Abreu, Iliano V; Sonoda, Ivan V; Fonseca, Jose A; Melo, Marcia A; Balbino, Valdir Q; Ramalho-Ortigão, Marcelo

    2008-10-03

    In our recently published article "Lutzomyia longipalpis s.l. in Brazil and the impact of the Sao Francisco River in the speciation of this sand fly vector" by Iliano V. Coutinho-Abreu et al. a sentence located in paragraph 8 in the Discussion section had its meaning altered due to the improper insertion of three words.

  16. Dynamic study of the upper Sao Francisco River and the Tres Marias reservoir using MSS/LANDSAT images. [Brazil

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Sausen, T. M.

    1981-01-01

    The use of LANDSAT multispectral ban scanner imagery to verify the relationship between the behavior of the Tres Marias reservoir and the dynamics of the Sao Francisco River supply basin is described. The dispersion of suspended sediments and their concentration in the surface layers of the water are considered. A five year survey of the region during both dry and rainy seasons was performed. The drainage network was analyzed based on the patterns of dessication, water rises and soil use in the supply basin. Surface layers of the reservoir were tabulated as a function of the levels of gray in the imagery. In situ observations of water depth and reflectance were performed. Ground truth and LANDSAT data were correlated to determine the factors affecting the dynamics of the supply basin.

  17. Superposed folding and associated fracturing influence hypogene karst development in Neoproterozoic carbonates, São Francisco Craton, Brazil

    NASA Astrophysics Data System (ADS)

    Ennes-Silva, Renata A.; Bezerra, Francisco H. R.; Nogueira, Francisco C. C.; Balsamo, Fabrizio; Klimchouk, Alexander; Cazarin, Caroline L.; Auler, Augusto S.

    2016-01-01

    Porosity and permeability along fractured zones in carbonates could be significantly enhanced by ascending fluid flow, resulting in hypogene karst development. This work presents a detailed structural analysis of the longest cave system in South America to investigate the relationship between patterns of karst conduits and regional deformation. Our study area encompasses the Toca da Boa Vista (TBV) and Toca da Barriguda (TBR) caves, which are ca. 107 km and 34 km long, respectively. This cave system occurs in Neoproterozoic carbonates of the Salitre Formation in the northern part of the São Francisco Craton, Brazil. The fold belts that are around and at the craton edges were deformed in a compressive setting during the Brasiliano orogeny between 750 and 540 Ma. Based on the integrated analysis of the folds and brittle deformation in the caves and in outcrops of the surrounding region, we show the following: (1) The caves occur in a tectonic transpressive corridor along a regional thrust belt; (2) major cave passages, at the middle storey of the system, considering both length and frequency, developed laterally along mainly (a) NE-SW to E-W and (b) N to S oriented anticline hinges; (3) conduits were formed by dissolutional enlargement of subvertical joints, which present a high concentration along anticline hinges due to folding of competent grainstone layers; (4) the first folding event F1 was previously documented in the region and corresponds with NW-SE- to N-S-trending compression, whereas the second event F2, documented for the first time in the present study, is related to E-W compression; and (5) both folding events occurred during the Brasiliano orogeny. We conclude that fluid flow and related dissolution pathways have a close relationship with regional deformation events, thus enhancing our ability to predict karst patterns in layered carbonates.

  18. The Carrancas Formation, Bambuí Group: A record of pre-Marinoan sedimentation on the southern São Francisco craton, Brazil

    NASA Astrophysics Data System (ADS)

    Uhlein, Gabriel J.; Uhlein, Alexandre; Halverson, Galen P.; Stevenson, Ross; Caxito, Fabrício A.; Cox, Grant M.; Carvalho, Jorge F. M. G.

    2016-11-01

    The Carrancas Formation outcrops in east-central Brazil on the southern margin of the São Francisco craton where it comprises the base of the late Neoproterozoic Bambuí Group. It is overlain by the basal Ediacaran cap carbonate Sete Lagoas Formation and was for a long time considered to be glacially influenced and correlative with the glaciogenic Jequitaí Formation. New stratigraphic, isotopic and geochronologic data imply that the Carrancas Formation was instead formed by the shedding of debris from basement highs uplifted during an episode of minor continental rifting. Reddish dolostones in the upper Carrancas Formation have δ13C values ranging from +7.1 to +9.6‰, which is a unique C isotopic composition for the lowermost Bambuí Group but similar to values found in the Tijucuçu sequence, a pre-glacial unit in the Araçuaí fold belt on the eastern margin of the São Francisco craton. The stratigraphic position below basal Ediacaran cap carbonates and the highly positive δ13C values together indicate a Cryogenian interglacial age for the Carrancas Formation, with the high δ13C values representing the so-called Keele peak, which precedes the pre-Marinoan Trezona negative δ13C excursion in other well characterized Cryogenian sequences. Hence, The Carrancas Formation pre-dates de Marinoan Jequitaí Formation and represents an interval of Cryogenian stratigraphy not previously known to occur on the southern margin of São Francicso craton. Documentation of Cryogenian interglacial strata on the São Francisco craton reinforces recent revisions to the age of Bambuí Group strata and has implications for the development of the Bambuí basin.

  19. Lutzomyia longipalpis s.l. in Brazil and the impact of the Sao Francisco River in the speciation of this sand fly vector.

    PubMed

    Coutinho-Abreu, Iliano V; Sonoda, Ivan V; Fonseca, Jose A; Melo, Marcia A; Balbino, Valdir Q; Ramalho-Ortigão, Marcelo

    2008-06-12

    Lutzomyia longipalpis s.l. (Diptera: Psychodidae) is the principal vector of Leishmania infantum chagasi in the Americas, and constitutes a complex of species. Various studies have suggested an incipient speciation process based on behavioral isolation driven by the chemotype of male sexual pheromones. It is well known that natural barriers, such as mountains and rivers can directly influence population divergence in several organisms, including insects. In this work we investigated the potential role played by the Sao Francisco River in eastern Brazil in defining the current distribution of Lu. longipalpis s.l. Our studies were based on analyses of polymorphisms of the cytochrome b gene (cyt b) sequences from Lu. longipalpis s.l. available in public databases, and from additional field-caught individuals. Altogether, 9 distinct populations and 89 haplotypes were represented in the analyses. Lu. longipalpis s.l. populations were grouped according to their distribution in regards to the 10 degrees S parallel: north of 10 degrees S (<10 degrees S); and south of 10 degrees S (>10 degrees S). Our results suggest that although no polymorphisms were fixed, moderate genetic divergences were observed between the groups analyzed (i.e., FST = 0.184; and Nm = 2.22), and were mostly driven by genetic drift. The population divergence time estimated between the sand fly groups was about 0.45 million years (MY), coinciding with the time of the change in the course of the Sao Francisco River, during the Mindel glaciation. Overall, the polymorphisms on the cyt b haplotypes and the current speciation process detected in Lu. longipalpis s.l. with regards to the distribution of male sexual pheromones suggest a role of the Sao Francisco River as a significant geographical barrier in this process.

  20. Lutzomyia longipalpis s.l. in Brazil and the impact of the Sao Francisco River in the speciation of this sand fly vector

    PubMed Central

    Coutinho-Abreu, Iliano V; Sonoda, Ivan V; Fonseca, Jose A; Melo, Marcia A; Balbino, Valdir Q; Ramalho-Ortigão, Marcelo

    2008-01-01

    Lutzomyia longipalpis s.l. (Diptera: Psychodidae) is the principal vector of Leishmania infantum chagasi in the Americas, and constitutes a complex of species. Various studies have suggested an incipient speciation process based on behavioral isolation driven by the chemotype of male sexual pheromones. It is well known that natural barriers, such as mountains and rivers can directly influence population divergence in several organisms, including insects. In this work we investigated the potential role played by the Sao Francisco River in eastern Brazil in defining the current distribution of Lu. longipalpis s.l. Our studies were based on analyses of polymorphisms of the cytochrome b gene (cyt b) sequences from Lu. longipalpis s.l. available in public databases, and from additional field-caught individuals. Altogether, 9 distinct populations and 89 haplotypes were represented in the analyses. Lu. longipalpis s.l. populations were grouped according to their distribution in regards to the 10°S parallel: north of 10°S (<10°S); and south of 10°S (>10°S). Our results suggest that although no polymorphisms were fixed, moderate genetic divergences were observed between the groups analyzed (i.e., FST = 0.184; and Nm = 2.22), and were mostly driven by genetic drift. The population divergence time estimated between the sand fly groups was about 0.45 million years (MY), coinciding with the time of the change in the course of the Sao Francisco River, during the Mindel glaciation. Overall, the polymorphisms on the cyt b haplotypes and the current speciation process detected in Lu. longipalpis s.l. with regards to the distribution of male sexual pheromones suggest a role of the Sao Francisco River as a significant geographical barrier in this process. PMID:18549496

  1. Archean crustal evolution in the Southern São Francisco craton, Brazil: Constraints from U-Pb, Lu-Hf and O isotope analyses

    NASA Astrophysics Data System (ADS)

    Albert, Capucine; Farina, Federico; Lana, Cristiano; Stevens, Gary; Storey, Craig; Gerdes, Axel; Dopico, Carmen Martínez

    2016-12-01

    In this study we present U-Pb and Hf isotope data combined with O isotopes in zircon from Neoarchean granitoids and gneisses of the southern São Francisco craton in Brazil. The basement rocks record three distinct magmatic events: Rio das Velhas I (2920-2850 Ma), Rio das Velhas II (2800-2760 Ma) and Mamona (2750-2680 Ma). The three sampled metamorphic complexes (Bação, Bonfim and Belo Horizonte) have distinct εHf vs. time arrays, indicating that they grew as separate terranes. Paleoarchean crust is identified as a source which has been incorporated into younger magmatic rocks via melting and mixing with younger juvenile material, assimilation and/or source contamination processes. The continental crust in the southern São Francisco craton underwent a change in magmatic composition from medium- to high-K granitoids in the latest stages, indicating a progressive HFSE enrichment of the sources that underwent anatexis in the different stages and possibly shallowing of the melting depth. Oxygen isotope data shows a secular trend towards high δ18O (up to 7.79‰) indicating the involvement of metasediments in the petrogenesis of the high potassium granitoids during the Mamona event. In addition, low δ18O values (down to 2.50‰) throughout the Meso- and Neoarchean emphasize the importance of meteoritic fluids in intra-crustal magmatism. We used hafnium isotope modelling from a compilation of detrital zircon compositions to constrain crustal growth rates and geodynamics from 3.50 to 2.65 Ga. The modelling points to a change in geodynamic process in the southern São Francisco craton at 2.9 Ga, from a regime dominated by net crustal growth in the Paleoarchean to a Neoarchean regime marked by crustal reworking. The reworking processes account for the wide variety of granitoid magmatism and are attributed to the onset of continental collision.

  2. Provenance of zircon xenocrysts in the Neoproterozoic Brauna Kimberlite Field, São Francisco Craton, Brazil: Evidence for a thick Palaeoproterozoic lithosphere beneath the Serrinha block

    NASA Astrophysics Data System (ADS)

    Donatti-Filho, José Paulo; Oliveira, Elson P.; McNaughton, Neal J.

    2013-08-01

    The 642 Ma-old Brauna Kimberlite Field is located on the northeastern sector of the São Francisco Craton (Serrinha block) and is one of the rare Neoproterozoic kimberlitic events in South America. Zircon xenocrysts from the volumetric most important kimberlite pipes Brauna 03, Brauna 07 and Brauna 04 were used as a tool to identify different components of the lithosphere beneath the northeast region of the São Francisco craton. A composite kimberlite sample of eight representative and different drill holes and three samples of the host rocks (Nordestina granodiorite) were sampled for SHRIMP geochronology. The results were compared with precise U-Pb age data for the regional rocks, i.e. the Archaean basement and the Palaeoproterozoic Rio Itapicuru greenstone belt. Samples from the Nordestina granodiorite gave three different ages: 2155 Ma in the western part of the batholith, 2139 Ma in its central part, and 2132 Ma in its eastern part. Zircon 207Pb/206Pb ages of the Brauna kimberlite zircon grains spread over the timespan 2107-2223 Ma and indicate four age groups at 2105 ± 3 Ma, 2138 ± 7 Ma, 2166 ± 5 Ma, and 2198 ± 4 Ma. Source rocks for the three former age groups can be found in the Rio Itapicuru greenstone belt, including zircon xenocrysts from the Nordestina granodiorite, whereas the latter age group has not yet been reported in the Serrinha block. The new zircon ages show that only rocks of the Palaeoproterozoic Rio Itapicuru greenstone belt and of a hidden 2.17-2.20 Ga crust were sampled by the kimberlite magma during its ascent through the lithosphere. It is proposed that there is none or a few Archaean crust beneath the kimberlite emplacement area, hence implying a thick Palaeoproterozoic lithosphere for this portion of the São Francisco craton.

  3. Neoarchean and Paleoproterozoic granitoids marginal to the Jeceaba-Bom Sucesso lineament (SE border of the southern São Francisco craton): Genesis and tectonic evolution

    NASA Astrophysics Data System (ADS)

    Campos, José Carlos Sales; Carneiro, Maurício Antônio

    2008-12-01

    The sialic crust of the southern São Francisco craton along the Jeceaba-Bom Sucesso lineament, central-southern part of Minas Gerais (Brazil), encompasses, among other rock types, Neoarchean and Paleoproterozoic granitoids. These granitoids, according to their petrographic, lithogeochemical and geochronologic characteristics, were grouped into two Neoarchean suites (Samambaia-Bom Sucesso and Salto Paraopeba-Babilônia) and three Paleoproterozoic suites (Cassiterita-Tabuões, Ritápolis and São Tiago). Varied processes and tectonic environments were involved in the genesis of these suites. In particular, the lithogeochemistry of the (Archean and Paleoproterozoic) TTG-type granitoids indicates an origin by partial melting of hydrated basaltic crust in a subduction environment. In the Neoarchean, between 2780 and 2703 Ma, a dominant TTG granitoid genesis related to an active continental margin was followed by another granite genesis related to crustal anatexis processes at 2612-2550 Ma. In the Paleoproterozoic, the generation of TTG and granites s.s. occurred at three distinct times: 2162, 2127 and 1887 Ma. This fact, plus the rock-type diversity produced by this granite genesis, indicates that the continental margin of the southern portion of the São Francisco craton was affected by more than one consumption episode of oceanic crust, involving different island arc segments, and the late Neoarchean consolidate continent. A Paleoproterozoic tectonic evolution in three stages is proposed in this work.

  4. Disclosing the Paleoarchean to Ediacaran history of the São Francisco craton basement: The Porteirinha domain (northern Araçuaí orogen, Brazil)

    NASA Astrophysics Data System (ADS)

    Silva, Luiz Carlos da; Pedrosa-Soares, Antonio Carlos; Armstrong, Richard; Pinto, Claiton Piva; Magalhães, Joana Tiago Reis; Pinheiro, Marco Aurélio Piacentini; Santos, Gabriella Galliac

    2016-07-01

    This geochronological and isotopic study focuses on one of the Archean-Paleoproterozoic basement domains of the São Francisco craton reworked in the Araçuaí orogen, the Porteirinha domain, Brazil. It also includes a thorough compilation of the U-Pb geochronological data related to the adjacent Archean and Rhyacian terranes from the São Francisco craton and Araçuaí orogen. The main target of this study is the TTG gneisses of the Porteirinha complex (Sample 1). The gneiss dated at 3371 ± 6 Ma unraveled a polycyclic evolution characterized by two metamorphic overprinting episodes, dated at 3146 ± 24 Ma (M1) and ca. 600 Ma (M2). The former (M1) is so far the most reliable evidence of the oldest metamorphic episode ever dated in Brazil. The latter (M2), in turn, is endemic in most of the exposed eastern cratonic margin within the Araçuaí orogen. Whole-rock Sm-Nd analysis from the gneiss provided a slightly negative εNd(t3370) = - 0.78 value, and a depleted mantle model (TDM) age of 3.5 Ga, indicating derivation mainly from the melting of a ca. 3.5 Ga tholeiitic source. Sample 2, a K-rich leuco-orthogneiss from the Rio Itacambiriçu Complex, was dated at 2657 ± 25 Ma and also presents a ca. 600 Ma M2 overprinting M2 age. The other two analyses were obtained from Rhyacian granitoids. Sample 3 is syn-collisional, peraluminous leucogranite from the Tingui granitic complex, showing a crystallization age of 2140 ± 14 Ma and strong post-crystallization Pb*-loss, also ascribed to the Ediacaran overprinting. Accordingly, it is interpreted as a correlative of the late Rhyacian (ca. 2150-2050 Ma) collisional stage of the Mantiqueira orogenic system/belt (ca. 2220-2000 Ma), overprinted by the Ediacaran collage. Sample 4 is a Rhyacian post-orogenic (post-collisional), mixed-source, peralkaline, A1-type suite, with a crystallization age of 2050 ± 10 Ma, presenting an important post-crystallization Pb*-loss related to Ediacaran collision. The focused region records some

  5. The Tectonic interaction between the Paramirim aulacogen and the Araçuaí belt, São Francisco craton region, Eastern Brazil.

    PubMed

    Cruz, Simone C P; Alkmim, Fernando F

    2006-03-01

    The Paramirim aulacogen, hosted in the northern part of the São Francisco craton, corresponds to two superimposed and partially inverted rifts of Paleo and Neoproterozoic ages. The Rio Pardo salient of the Araçuaí belt defines the local limit of the craton and interferes with the aulacogen structures. In order to understand the mechanism and timing of the tectonic interaction between these tectonic features during the inversion processes, a structural analysis was undertaken in the southern Paramirim aulacogen and along the Rio Pardo salient. The results obtained indicate that the Rio Pardo salient formed during an early stage of closure of the Neoproterozoic Macaúbas rift system and consequent initiation of the Araçuaí orogen. The orogenic front propagated further northwards into the craton, causing a first stage of inversion in the southern terminus of the aulacogen trough. Subsequently, the Paramirim aulacogen experienced the main stage of inversion, which led to the development of a NNW-oriented basement involved fold-thrust system. These fabric elements overprint the Rio Pardo salient, and the structures of both the first and second stages of inversion affect the Salitre Formation, the youngestNeoproterozoic unit of the area, clearly indicating a Late Neoproterozoic maximum age for all the inversion stages of the Paramirim aulacogen.

  6. Fission track analysis of apatites from São Francisco craton and Mesozoic alcaline-carbonatite complexes from central and southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Amaral, G.; Born, H.; Hadler, J. C. N.; Iunes, P. J.; Kawashita, K.; Machado, D. L.; Oliveira, E. P.; Paulo, S. R.; Tello, C. A. S.

    1997-07-01

    Thermal histories on seven Brazilian apatites were obtained by fission track analysis using Monte Carlo simulations. The apatites were collected from two distinct geotectonic provinces. One group, originated from São Francisco craton, represents a typical cratonic domain with Proterozoic and Eopaleozoic rocks and yielded Permo-Triassic ages (counted since the instant when temperature was low enough so that the damage produced by fission tracks in apatite started to be preserved). The common thermal history accepted by all samples of this group is a linear cooling from ~90 to ~25 °C for the last 240 Ma, in agreement with present day thermal gradient and denudation rates. The other group, from Mesozoic alkaline-carbonatite complexes, in central and southeastern Brazil, yielded Cretaceous ages, close to those of the intrusions. For the samples of central Brazil, fission track analysis suggests a slow cooling from ~95 ° to ~85 °C between 90 and 60 Ma ago, followed by a faster cooling from ~85 ° to ~27 °C for the last 60 Ma. Otherwise, two trends exist for the samples of southeastern Brazil. The primary one is an increase in temperature from ~75 ° to ~95 °C, which occurred between 140 and 60 Ma ago. In this period, there is also another trend: a cooling from ~100 ° to ~80 °C. However, both trends are followed by a common thermal history during the last 60 Ma: a cooling from approximately ~80 ° to ~25 °C.

  7. Asymmetry of Non-Volcanic Passive Margins Induced by the Proximity of a Craton

    NASA Astrophysics Data System (ADS)

    Andres-Martinez, M.; Perez-Gussinye, M.; Morgan, J. P.; Araujo, M. N.

    2015-12-01

    Symmetry of conjugated rifted margins is controlled by the rheology of the crust and the mantle, extension velocities and heterogeneities in the lithosphere. However, there is a lack of knowledge on how the feedbacks between these initial conditions influence the final architecture of passive margins and the polarity of the asymmetry. Here we focus on cratons as stiff heterogeneities which potentially induce asymmetry. For simplicity, we choose to address only non-volcanic rifted margins developed next to cratons, such as the Brazil-Congo and Australia-Antarctica margin pairs. In the South Atlantic case, where cratons are closer to the margins (north of Sao Francisco craton and north and south of Congo craton) the margins are narrow, while wide margins develop far away from cratons. Extreme asymmetry occurs where rifting takes place close to a craton in one margin (narrow) and a fold belt in the conjugate (wide). The same is observed for the Australia-Antarctic pair in the sector of Recherche basin, where the Australian margin is narrow next to the Yilgarn craton and widens towards the east as it lays further from the craton. We use numerical models in order to study how cratons induce asymmetry of conjugated rifted margins and affect the polarity of the asymmetry. We ran experiments with different lower crustal rheologies for a fold belt lithosphere in order to understand which rheologies 'naturally' result in asymmetric margins. We also ran experiments where a cratonic lithosphere is placed next to a fold belt lithosphere, and where rifting is initiated by a weak seed in the fold belt at different distances from the craton. We found that where some fold belt experiments result in symmetric margins, their equivalent experiments with craton result in asymmetric margins. Furthermore, strong- and intermediate-rheology experiments with cratons showcase narrow margins in the craton side and wide margins on the fold belt side. We also observe that the distance from the

  8. Studies of the Hydrological Cycle for the Sao Francisco Basin using a combination of modeling and satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Rebello, V.; Martins, T.; Rotunno Filho, O. C.; Araujo, A. A.; Lakshmi, V.

    2015-12-01

    The EPHSTC land surface hydrological model is used here in a case study for the São Francisco River Basin (area 630.000 km²) located in Northeast Brazil. The model solves the surface fluxes using ISBA prognostic equations and a gravitational drainage, a vertical diffusion process. A mechanism for subgrid-scale surface runoff generation was added. Another feature implemented in this model is the lateral redistribution of the soil water. This work will be a first attempt of evaluating EPHSTC results in a Brazil catchment for a long time period - 2001 to 2014. The GLDAS model input surface parameters would be used. Validation will be performed by the model values of soil moisture with corresponding GDLAS soil moisture (0-10,10-40,40-60 cm) and latent and heat fluxes. The two time series will be compared by calculation of the coefficient of determination and root mean square error.

  9. 3-D inversion of complex magnetotelluric data from an Archean-Proterozoic terrain in northeastern São Francisco Craton, Brazil

    NASA Astrophysics Data System (ADS)

    Bologna, Mauricio S.; Egbert, Gary D.; Padilha, Antonio L.; Pádua, Marcelo B.; Vitorello, Ícaro

    2017-09-01

    We present a magnetotelluric (MT) study in the northeastern part of the São Francisco Craton that encompasses an Archean-Proterozoic terrain, the Serrinha Block, breached by a rift basin developed mostly in Early Cretaceous times during the opening of the South Atlantic Ocean. Even though the MT sites are regularly spaced, the profiles have different orientations from one another, making the data distribution over the area highly uneven and therefore non-ideal for 3-D modeling. However, the data set is very complex, with dimensionality analysis indicating prevalence of 3-D geoelectric structure. Results from 3-D inversion are evaluated for robustness and potentiality for yielding tectonic information. At upper crustal depths, the resulting 3-D model is coherent with surface geology, whereas at mid and lower crustal depths more cryptic structures are revealed, likely of Palaeoproterozoic age. The most striking features in the model are several strong (∼1 Ωṡm) crustal conductors beneath the central part of the Serrinha Block, which we attribute to a Palaeoproterozoic oceanic plate subduction and arc-continent collision event involving the Rio Itapicuru Greenstone Belt and the basement of the Serrinha Block. The west-dipping geometry of these conductors provides a constraint on subduction polarity and gives support to tectonic evolutionary models proposing that the Rio Itapicuru Belt was formed in an island arc environment.

  10. Evolution of the Paleoproterozoic crust in the southern portion of the San Francisco Craton - Cinturão Mineiro- Brazil

    NASA Astrophysics Data System (ADS)

    Barbosa, N. S.; Teixeira, W.; Avila, C.

    2013-12-01

    The Mineiro belt was formed by continuous amalgamation of magmatic arcs, largely juvenile whereas crustal contamination is also present. Its evolution lasted about 450 Ma, from the Siderian to the Orosirian period (2450-2000 Ma), as part of the Minas accretionary orogeny that evolved along an Archean/Early Proterozoic foreland. Paleoproterozoic granitic bodies outcrops throughout the Mineiro belt and are related to the tectonic evolution of the Minas accretionary orogen, which was interpreted as an accretion of Resende Costa (2.33 Ga), Serrinha (2.22 Ga), Ritápolis (2.15 Ga) and Alto do Maranhão (2.10 Ga) magmatic arcs, where the vast difference in ages points to a Paleoproterozoic polycyclic evolution for this sector of the craton. The metagranitoids are heterogeneous, have variable sizes, and some of them may reach batholitic proportions, as it is the case of the pluton Ritápolis. Spatially, these granitoids are limited to the north by units represented by Archean gneissic migmatitic complex, by the Rio das Velhas Supergroup (3.2-2.7 Ga) and by the Paleoproterozoic Minas Supergroup (2.6-2.4 Ga). Southward it is limited by the Meso-Neoproterozoic metasedimentary sequences whose minimum ages of deposition correspond, respectively, to 1.53 Ga, 1.38 Ga and between 1.14 Ga and 950 Ma (Ribeiro et al., 2013; Bethlehem et al., 2012). Geochronological studies recently developed in this portion of the Paleoproterozoic Craton show that its evolution begins in the Siderian and extends until the Riacian (Ávila et al., 2010; Seixas et al., 2012), where small crustal fragments correspond to remnants of the first arcs generated in the Siderian Mineiro belt (e.g.: Cassiterita orthogneiss). The rocks representative of these arcs consists mainly of orthogneisses with tonalitic to granitic compositions. The Cassiterita tonalitic orthogneiss outcrops north of the Lenheiro shear zone. The rocks of this body are slighty foliated; this foliation is characterized by the preferred

  11. Tectonic fabric revealed by AARM of the proterozoic mafic dike swarm in the Salvador city (Bahia State): São Francisco Craton, NE Brazil

    NASA Astrophysics Data System (ADS)

    Raposo, M. Irene B.; Berquó, Thelma S.

    2008-04-01

    Magnetic fabric and rock magnetism studies were performed on 25 unmetamorphosed mafic dikes of the Meso-Late Proterozoic (˜1.02 Ga) dike swarm from Salvador (Bahia State, NE Brazil). This area lies in the north-eastern part of the São Francisco Craton, which was dominantly formed/reworked during the Transamazonian orogeny (2.14-1.94 Ga). The dikes crop out along the beaches and in quarries around Salvador city, and cut across both amphibolite dikes and granulites. Their widths range from a few centimeters up to 30 m with an average of ˜4 m, and show two main trends N140-190 and N100-120 with vertical dips. Magnetic fabrics were determined using both anisotropy of low-field magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM). The magnetic mineralogy was investigated by many experiments including remanent magnetization measurements at variable low temperatures (10-300 K), Mössbauer spectroscopy, high temperature magnetization curves (25-700 °C) and scanning electron microscopy (SEM). The rock magnetism study suggests pseudo-single-domain magnetite grains carrying the bulk magnetic susceptibility and AARM fabrics. The magnetite grains found in these dikes are large and we discard the presence of single-domain grains. Its composition is close to stoichiometric with low Ti substitution, and its Verwey transition occurs around 120 K. The main AMS fabric recognized in the swarm is so-called normal, in which the Kmax- Kint plane is parallel to the dike plane and the magnetic foliation pole ( Kmin) is perpendicular to it. This fabric is interpreted as due to magma flow, and analysis of the Kmax inclination permitted to infer that approximately 80% of the dikes were fed by horizontal or sub-horizontal flows ( Kmax < 30°). This interpretation is supported by structural field evidence found in five dikes. In addition, based on the plunge of Kmax, two mantle sources could be inferred; one of them which fed about 80% of the swarm

  12. Geochemistry of komatiites and basalts from the Rio das Velhas and Pitangui greenstone belts, São Francisco Craton, Brazil: Implications for the origin, evolution, and tectonic setting

    NASA Astrophysics Data System (ADS)

    Verma, Sanjeet K.; Oliveira, Elson P.; Silva, Paola M.; Moreno, Juan A.; Amaral, Wagner S.

    2017-07-01

    The Neoarchean Rio das Velhas and Pitangui greenstone belts are situated in the southern São Francisco Craton, Minas Gerais, Brazil. These greenstone belts were formed between ca. 2.79-2.73 Ga, and consist mostly of mafic to ultramafic volcanics and clastic sediments, with minor chemical sediments and felsic volcanics that were metamorphosed under greenschist facies. Komatiites are found only in the Rio das Velhas greenstone belt, which is composed of high-MgO volcanic rocks that have been identified as komatiites and high-Mg basalts, based on their distinctive geochemical characteristics. The Rio das Velhas komatiites are composed of tremolite + actinolite + serpentine + albite with a relict spinifex-texture. The Rio das Velhas komatiites have a high magnesium content ((MgO)adj ≥ 28 wt.%), an Al-undepleted Munro-type [(Al2O3/TiO2)adj and (CaO/Al2O3)adj] ratio ranging from 27 to 47 and 0.48 to 0.89, relatively low abundances of incompatible elements, a depletion of light rare earth elements (LREE), a pattern of non-fractionated heavy rare- earth elements (HREE), and a low (Gd/Yb)PM ratio (≤ 1.0). Negative Ce anomalies suggest that alteration occurred during greenschist facies metamorphism for the komatiites and high-Mg basalts. The low [(Gd/Yb)PM < 1.0] and [(CaO/Al2O3)adj < 0.9)], high [(Al2O3/TiO2)adj > 18] and high HREE, Y, and Zr content suggest that the Rio das Velhas komatiites were derived from the shallow upper mantle without garnet involvement in the residue. The chemical compositions [(Al2O3/TiO2)adj, (FeO)adj, (MgO)adj, (CaO/Al2O3)adj, Na, Th, Ta, Ni, Cr, Zr, Y, Hf, and REE] indicate that the formation of the komatiites, high-Mg basalts and basalts occurred at different depths and temperatures in a heterogeneous mantle. The komatiites and high-Mg basalts melted at liquidus temperatures of 1450-1550 °C. The Pitangui basalts are enriched in the highly incompatible LILE (large-ion lithophile elements) relative to the moderately incompatible HFS (high

  13. The 2012-2013 Montes Claros earthquake series in the São Francisco Craton, Brazil: new evidence for non-uniform intraplate stresses in mid-plate South America

    NASA Astrophysics Data System (ADS)

    Agurto-Detzel, Hans; Assumpção, Marcelo; Ciardelli, Caio; Albuquerque, Diogo Farrapo; Barros, Lucas V.; França, George S. L.

    2015-01-01

    On 2012 May 19, an mb = 4 earthquake shook the town of Montes Claros, Brazil in the middle of the São Francisco Craton. Because of the scarce seismicity in the area, an event like this could provide valuable information to characterize the governing seismotectonics and stress field for the region. Here, we present the results of more than 1 yr of local seismic monitoring after the main shock. We found that the seismicity originated at approximately 1-km depth in an NNW-oriented blind reverse fault, dipping to the E. The magnitude of the main shock was 4mb, with aftershocks reaching up to 3.6mb. Focal mechanisms from first motion polarities and waveform moment tensor inversions indicate a reverse faulting in agreement with the orientation of the aftershock locations. In addition, we derived a new 1-D local velocity model using a simultaneous inversion of hypocentres and velocity layers. The results indicate P-wave velocities of 4.5 km s-1 for the upper layer of carbonate rocks and 5.23 and 5.69 km s-1 for the lower fractured and compact crystalline basement layers, respectively. Higher Vp/Vs ratios were obtained for the upper two layers compared to the lowermost layer, possibly indicating presence of rock fracturing and percolated water. The calculated stress drop for the main event is 0.33 MPa, which is a relatively low value for an intraplate earthquake but still within the observed range. The inversion of the main shock focal mechanism and previously published focal mechanisms suggests a compressional stress regime in the central part of the São Francisco Craton, which is different from the strike-slip regime in the southern part, although both have an EW-oriented σ1. On the other hand, focal mechanisms of events located to the west of the craton indicate an NW-SE oriented σ1 for central Brazil. This variability highlights the importance of local sources of stresses (e.g. flexural stresses) in mid-plate South America, unlike other mid-plate areas of the world

  14. The Intracratonic Caraibas-Itacarambi Earthquake of December 9, 2007 (4.9 mb), Minas Gerais, Brazil: predominance of compressional stresses in the middle of the San Francisco craton.

    NASA Astrophysics Data System (ADS)

    Chimpliganond, C. N.; Franca, G. S.; Barros, L. V.; Assumpcao, M.; Carvalho, J.

    2008-05-01

    An earthquake with magnitude 4.9 mb, in the central part of the San Francisco craton, shook the village of Caraibas, Minas Gerais state, on December 9, 2007 at 00:03 (local time). The epicentral area is near the city of Itacarambi. This event was the first to cause a fatal victim in Brazil (a little girl 6 years old). The maximum intensity reached VII Modified Mercalli and the isoseismal of VI MM intensity comprise an area of about 100 square kilometers. Since May 25, 2007, when a 3.5 mb magnitude event was widely felt by the population, this region has been shaken by small earthquakes. A field campaign was taken during October 23-28 to implement a local seismographic network composed by 6 tri-axial broadband stations that is operating until now. A seismic gap was observed some days before the main shock of December 9. Two imminent foreshocks preceded the main shock by some minutes, and 162 aftershocks followed the main event during the first day. The earthquakes with clear onset times for P and S waves were located with Hypo71 using a local velocity model with a Vp/Vs ratio of 1.72, obtained with a composite Wadati diagram. The events show a trend in the NE-SW direction, with very shallow depths, less than about 2 kilometers. The aftershocks were distributed over an area about 3 kilometers long in the NE-SW direction. A composite focal mechanism, determined using P-wave polarities with the clearest waveforms at local stations, shows a reverse faulting mechanism. This solution, consistent with P-wave polarity data for the main shock recorded at regional and teleseismic stations, shows a near horizontal P-axis trending E- W, similar to an earthquake swarm occurred 50 km to the north in 1990. Stress inversion using five different focal mechanisms in this part of the San Francisco craton indicates compressional stresses with EW maximum compression (S1) and a NS intermediate compression (S2).

  15. New insight on the paleoproterozoic evolution of the São Francisco Craton: Reinterpretation of the geology, the suture zones and the thicknesses of the crustal blocks using geophysical and geological data

    NASA Astrophysics Data System (ADS)

    Sampaio, Edson E. S.; Barbosa, Johildo S. F.; Correa-Gomes, Luiz C.

    2017-07-01

    The Archean-Paleoproterozoic Jequié (JB) and Itabuna-Salvador-Curaçá (ISCB) blocks and their tectonic transition zone in the Valença region, Bahia, Brazil are potentially important for ore deposits, but the geological knowledge of the area is still meager. The paucity of geological information restricts the knowledge of the position and of the field characteristics of the tectonic suture zone between these two crustal segments JB and ISCB. Therefore, interpretation of geophysical data is necessary to supplement the regional structural and petrological knowledge of the area as well as to assist mining exploration programs. The analysis of the airborne radiometric and magnetic data of the region has established, respectively, five radiometric domains and five magnetic zones. Modeling of a gravity profile has defined the major density contrasts of the deep structures. The integrated interpretation of the geophysical data fitted to the known geological information substantially improved the suture zone (lower plate JB versus upper plate ISCB) delimitation, the geological map of the area and allowed to estimate the thicknesses of these two blocks, and raised key questions about the São Francisco Craton tectonic evolution.

  16. [Evaluation of a program for the control of schistosomiasis in municipalities located on the basin of the Sao Francisco River, Minas Gerais, Brazil].

    PubMed

    Lima e Costa, M F; Guerra, H L; Pimenta, F G; Firmo, J O; Uchoa, E

    1996-01-01

    An evaluation of the control program on schistosomiasis (PCE/PCDEN) was performed in the region of São Francisco river in MInas Gerais. The study area comprises six municipalities, with 130,000 inhabitants and 916 localities situated in an area with 10,722 km2. The activities initiated in 1983-85 in four municipalities and in 1987 in the other two. The main measures of control were repeated treatment with oxamniquine and use of niclosamide. The prevalence of infection by Schistosoma mansoni in the first four municipalities, that was initially around 18 and 32%, dropped abruptly after the first intervention (1983/85) and remained in levels below the initial ones until the last assessment (1990-94); similar trends were observed for the proportion of infected snails. In these municipalities, the proportion of localities without infection or with prevalence below 5% increased in relation to those with higher prevalence. In the other two municipalities, with initial prevalence below 5%, there were no substantial changes in S. mansoni prevalence or proportion of infected snails; the cost benefit of the program in these municipalities need to be assessed and the priorities redirected to eradicate focal areas and prevent spread to non infected localities. The authors call attention to the difficulties in the long term of a control program based on repeated treatments. Information on factors associated with S. mansoni infection in each locality, or in groups of similar localities, would allow to develop additional measures to treatment that could last longer and be less dependent on the continuous use of chemotherapy.

  17. The Caraguataí syenitic suite, a ca. 2.7 Ga-old alkaline magmatism (petrology, geochemistry and U-Pb zircon ages). Southern Gavião block (São Francisco Craton), Brazil

    NASA Astrophysics Data System (ADS)

    Cruz, Simone Cerqueira Pereira; Peucat, Jean-Jacques; Teixeira, Leo; Carneiro, Maurício Antônio; Marques Martins, Adriano Alberto; Santana, Jocilene dos Santos; de Souza, Jailma Santos; Barbosa, Johildo Salomão Figueiredo; Leal, Ângela Beatriz Menezes; Dantas, Elton; Pimentel, Marcio

    2012-08-01

    corresponding negative ɛ(t) values (-4 to -6), suggest that the alkaline magmas are mainly derived from partial melting of Paleoarchean gneisses in an intraplate setting similar to those from the surrounding Aracatu region. The isotopic data obtained in this work together with published data suggest that in the southern sector of the Gavião Block an important event of crustal recycling occurred ca. 2.7 Ga ago. Similar ages have been found in other parts of the São Francisco Craton.

  18. Sao Paulo Map Collections.

    ERIC Educational Resources Information Center

    McLean, G. Robert

    1985-01-01

    Describes geographical, subject, and chronological aspects of 25 cartographic collections housed in university, public, special, state, and semi-state libraries in Sao Paulo, Brazil. Three size categories of map holdings (more than 10,000, 1,000-10,000, less than 1,000) are distinguished. A list of 27 Sao Paulo institutions housing map collections…

  19. Sao Paulo Map Collections.

    ERIC Educational Resources Information Center

    McLean, G. Robert

    1985-01-01

    Describes geographical, subject, and chronological aspects of 25 cartographic collections housed in university, public, special, state, and semi-state libraries in Sao Paulo, Brazil. Three size categories of map holdings (more than 10,000, 1,000-10,000, less than 1,000) are distinguished. A list of 27 Sao Paulo institutions housing map collections…

  20. The Namuskluft and Dreigratberg sections in southern Namibia (Kalahari Craton, Gariep Belt): a geological history of Neoproterozoic rifting and recycling of cratonic crust during the dispersal of Rodinia until the amalgamation of Gondwana

    NASA Astrophysics Data System (ADS)

    Hofmann, Mandy; Linnemann, Ulf; Hoffmann, Karl-Heinz; Gerdes, Axel; Eckelmann, Katja; Gärtner, Andreas

    2014-07-01

    This paper presents combined U/Pb, Th/U and Hf isotope analyses on detrital and magmatic zircon grains together with whole-rock geochemical analyses of two basement and eight sedimentary rock samples from the Namuskluft and the Dreigratberg in southern Namibia (Gariep Belt). The sedimentary sections evolved during the Cryogenian on the SW part of the Kalahari Craton and where therefore deposited in an active rift setting during the break-up of Rodinia. Due to insufficient palaeomagnetic data, the position of the Kalahari Craton within Rodinia is still under discussion. There are possibilities to locate Kalahari along the western side of Australia/Mawsonland (Pisarevski et al. in Proterozoic East Gondwana: supercontinent assembly and break-up, Geological Society, London, 2003; Evans in Ancient Orogens and modern analogues. Geological Society, London, 2009; and others) or together with the Congo-Sao Francisco and Rio de la Plata Cratons (Li et al. in Prec Res 45: 203-2014, 2008; Frimmel et al. in Int J Earth Sci (Geol Rundsch) 100: 323-354, 2011; and others). It is sill unclear which craton rifted away from the Kalahari Craton during the Cryogenian. Although Middle to Upper Cryogenian magmatic activity is known for the SE Kalahari Craton (our working area) (Richtersveld Suite, Rosh Pinah Fm), all the presented samples show no U/Pb zircon ages younger than ca. 1.0 Ga and non-older than 2.06 Ga. The obtained U/Pb ages fit very well to the exposed basement of the Kalahari Craton (1.0-1.4 Ga Namaqua Province, 1.7-2.0 Ga Vioolsdrif Granite Suite and Orange River Group) and allow no correlation with a foreign craton such as the Rio de la Plata or Australia/Mawsonland. Lu-Hf isotopic signatures of detrital zircon point to the recycling of mainly Palaeoproterozoic and to a smaller amount of Archean crust in the source areas. ɛHf( t) signatures range between -24 and +14.8, which relate to TDM model ages between 1.05 and 3.1 Ga. Only few detrital zircon grains derived from

  1. Precambrian Cratons and Fold-Belts in Brazil: Overview

    NASA Astrophysics Data System (ADS)

    Fuck, R.

    2008-05-01

    The main Precambrian terrains recognized in Brazil comprise the Amazonian, São Francisco and Rio de la Plata cratons, surrounded by Neoproterozoic Brasiliano fold belts, making up the Borborema, Mantiqueira and Tocantins provinces. The Amazonian craton comprises an Archean core, surrounded by Paleoproterozoic terrains (Maroni-Itacaiunas, Ventuari-Tapajós, Rio Negro-Juruena), which southwestwards give way to the Mesoproterozoic Rondoniano-San Ignacio and Sunsas belts, the latter thought to be related to the Grenville belt of North America. The São Francisco craton comprises several Archean blocks (Gavião, Serrinha, Jequié) amalgamated by the Paleoproterozoic high-grade Itabuna-Salvador-Curaçá orogen. The Rio de la Plata craton, largely covered by Phanerozoic strata, is made of Paleoproterozoic basement gneiss and several Paleoproterozoic greenstone belts. Other cratonic blocks are hidden below large Phanerozoic basins, like the Paranapanema and Parnaíba blocks below the Paraná and Parnaíba basins, respectively. Several smaller Archean/Paleoproterozoic blocks appear within the Brasiliano provinces: some were strongly reworked during the Neoproterozoic orogenic events (São José do Campestre, Pernambuco-Alagoas, Goiás, Guanhães, Juiz de Fora, Curitiba), others were only marginally affected (São Luiz, Rio Apa, Luís Alves). The Brasiliano provinces are the result of Neoproterozoic to early Paleozoic orogenic events within the framework of West Gondwana amalgamation. The Mantiqueira Province extends from eastern Brazil to southern Uruguay and includes the Araçuaí, Ribeira and Dom Feliciano fold belts, bordering the São Francisco, Paranapanema and Rio de la Plata cratons and surrounding the Luís Alves craton. The Tocantins province in central Brazil includes the Araguaia, Paraguay and Brasília fold belts, the former bordering the Amazonian craton, the second bordering both the southern Amazonian craton and the Rio Apa block, and the last established on

  2. University of Sao Paulo

    SciTech Connect

    Acquadro, J.C.; Added, N.; Ferraretto, M.

    1995-08-01

    Argonne has agreed to assist the University of Sao Paulo (USP) in the construction of a small superconducting heavy-ion linac to serve as an energy booster for projectiles from their 8-MV tandem. This booster will be similar in many respects to the ANL booster linac built in the late 1970s. The ANL contribution to this project will be (1) to build (at USP expense) 14 split-ring niobium resonators and some of the associated rf electronics, (2) to provide technical information, and (3) to train USP staff members in several phases of superconducting-linac technology. Two Brazilian engineers worked at Argonne for one year, gaining experience in cryogenics and in superconducting-resonator technology. Another engineer worked on the new control system at ATLAS for two years, the first year supported by Sao Paulo and the second with direct ANL support. Sao Paulo personnel returned to ANL in 1993 for assembly and testing of the first batch of completed resonators. The fabrication of the resonators will be completed by early 1995 when the Sao Paulo personnel will come back for final assembly and testing. Fabrication of electronics modules at ANL is still in progress.

  3. Origin of cratonic basins

    NASA Astrophysics Data System (ADS)

    Dev. Klein, George; Hsui, Albert T.

    1987-12-01

    Tectonic subsidence curves show that the Illinois, Michigan, and Williston basins formed by initial fault-controlled mechanical subsidence during rifting and by subsequent thermal subsidence. Thermal subsidence began around 525 Ma in the Illinois Basin, 520 460 Ma in the Michigan Basin, and 530 500 Ma in the Williston Basin. In the Illinois Basin, a second subsidence episode (middle Mississippian through Early Permian) was caused by flexural foreland subsidence in response to the Alleghanian-Hercynian orogeny. Resurgent Permian rifting in the Illinois Basin is inferred because of intrusion of well-dated Permian alnoites; such intrusive rocks are normally associated with rifting processes. The process of formation of these cratonic basins remains controversial. Past workers have suggested mantle phase changes at the base of the crust, mechanical subsidence in response to isostatically uncompensated excess mass following igneous intrusions, intrusion of mantle plumes into the crust, or regional thermal metamorphic events as causes of basin initiation. Cratonic basins of North America, Europe, Africa, and South America share common ages of formation (around 550 to 500 Ma), histories of sediment accumulation, temporal volume changes of sediment fills, and common dates of interregional unconformities. Their common date of formation suggests initiation of cratonic basins in response to breakup of a late Precambrian super-continent. This supercontinent acted as a heat lens that caused partial melting of the lower crust and upper mantle followed by emplacement of anorogenic granites during extensional tectonics in response to supercontinent breakup. Intrusion of anorogenic granites and other partially melted intrusive rocks weakened continental lithosphere, thus providing a zone of localized regional stretching and permitting formation of cratonic basins almost simultaneously over sites of intrusion of these anorogenic granites and other partially melted intrusive rocks.

  4. Xingo: Capturing the potential of the Sao Francisco River

    SciTech Connect

    Oliveira, E.F. de Jr.; Vasconcelos, A.A. de; Mariz, L.A.

    1997-03-01

    Design and construction of a 3000 MW hydroelectric project in Brazil is outlined. Construction of the Xingo plant began in 1987; the final unit of the first phase is scheduled to enter service in the third quarter of 1997. Problems encountered during construction included financing and high flood flows; the steps taken to overcome these problems are described. Technical details of the plant are also summarized in the article.

  5. Understanding cratonic flood basalts

    NASA Astrophysics Data System (ADS)

    Silver, Paul G.; Behn, Mark D.; Kelley, Katherine; Schmitz, Mark; Savage, Brian

    2006-05-01

    The origin of continental flood basalts has been debated for decades. These eruptions often produce millions of cubic kilometers of basalt on timescales of only a million years. Although flood basalts are found in a variety of settings, no locale is more puzzling than cratonic areas such as southern Africa or the Siberian craton, where strong, thick lithosphere is breached by these large basaltic outpourings. Conventionally, flood basalts have been interpreted as melting events produced by one of two processes: 1) elevated temperatures associated with mantle plumes and/or 2) adiabatic-decompression melting associated with lithospheric thinning. In southern Africa, however, there are severe problems with both of these mechanisms. First, the rifting circumstances of several well-known basaltic outpourings clearly reflect lithospheric control rather than the influence of a deep-seated plume. Specifically, rift timing and magmatism are correlated with stress perturbations to the lithosphere associated with the formation of collisional rifts. Second, the substantial lithospheric thinning required for adiabatic decompression melting is inconsistent with xenolith evidence for the continued survival of thick lithosphere beneath flood basalt domains. As an alternative to these models, we propose a new two-stage model that interprets cratonic flood basalts not as melting events, but as short-duration drainage events that tap previously created sublithospheric reservoirs of molten basalt formed over a longer time scale. Reservoir creation/existence (Stage I) requires long-term (e.g. ≫ 1 Ma) supersolidus conditions in the sublithospheric mantle that could be maintained by an elevated equilibrium geotherm (appropriate for the Archean), a slow thermal perturbation (e.g. thermal blanketing or large-scale mantle upwelling), or a subduction-related increase in volatile content. The drainage event (Stage II) occurs in response to an abrupt stress change in the lithosphere, which

  6. Craton destruction and related resources

    NASA Astrophysics Data System (ADS)

    Zhu, Rixiang; Zhang, Hongfu; Zhu, Guang; Meng, Qingren; Fan, Hongrui; Yang, Jinhui; Wu, Fuyuan; Zhang, Zhiyong; Zheng, Tianyu

    2017-02-01

    Craton destruction is a dynamic event that plays an important role in Earth's evolution. Based on comprehensive observations of many studies on the North China Craton (NCC) and correlations with the evolution histories of other cratons around the world, craton destruction has be defined as a geological process that results in the total loss of craton stability due to changes in the physical and chemical properties of the involved craton. The mechanisms responsible for craton destruction would be as the follows: (1) oceanic plate subduction; (2) rollback and retreat of a subducting oceanic plate; (3) stagnation and dehydration of a subducting plate in the mantle transition zone; (4) melting of the mantle above the mantle transition zone caused by dehydration of a stagnant slab; (5) non-steady flow in the upper mantle induced by melting, and/or (6) changes in the nature of the lithospheric mantle and consequent craton destruction caused by non-steady flow. Oceanic plate subduction itself does not result in craton destruction. For the NCC, it is documented that westward subduction of the paleo-Pacific plate should have initiated at the transition from the Middle-to-Late Jurassic, and resulted in the change of tectonic regime of eastern China. We propose that subduction, rollback and retreat of oceanic plates and dehydration of stagnant slabs are the main dynamic factors responsible for both craton destruction and concentration of mineral deposits, such as gold, in the overriding continental plate. Based on global distribution of gold deposits, we suggest that convergent plate margins are the most important setting for large gold concentrations. Therefore, decratonic gold deposits appear to occur preferentially in regions with oceanic subduction and overlying continental lithospheric destruction/modification/growth.

  7. California: San Francisco Bay

    Atmospheric Science Data Center

    2014-05-15

    article title:  Northern California and San Francisco Bay     ... 17, 2000 (MISR) and August 25, 1997 (AirMISR) - Northern California and the San Francisco Bay. project:  MISR ... date:  Aug 17, 2000 Images:  California San Francisco Bay location:  United States ...

  8. Widespread refertilization of cratonic and circum-cratonic lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Tang, Yan-Jie; Zhang, Hong-Fu; Ying, Ji-Feng; Su, Ben-Xun

    2013-03-01

    Studies of mantle xenoliths have confirmed that Archean subcontinental lithospheric mantle (SCLM) is highly depleted in basaltic components (such as Al, Ca and Na) due to high-degree extraction of mafic and ultramafic melts and thus is refractory and buoyant, which made it chronically stable as tectonically independent units. However, increasing studies show that ancient SCLM can be refertilized by episodic rejuvenation events like infiltration of upwelling fertile material. The North China Craton is one of the most typical cases for relatively complete destruction of its Archean keel since the eruption of Paleozoic kimberlites, as is evidenced by a dramatic change in the compositions of mantle xenoliths sampled by Paleozoic to Cenozoic magmas, reflecting significant lithospheric thinning and the change in the character of the SCLM. The compositional change has been interpreted as the result of refertilization of Archean SCLM via multiple-stage peridotite-melt reactions, suggested by linear correlations between MgO and indices of fertility, covariations of Al2O3 with CaO, La/Yb, 87Sr/86Sr, 143Nd/144Nd, 187Os/188Os and Re-depletion ages (TRD), high Re abundances, scatter in Re-Os isotopic plot, variable in situ TRD ages of sulfides, and correlation between TRD ages and olivine Fo of peridotite xenoliths in Paleozoic kimberlites and Cenozoic basalts on the craton. By integrating major and trace element, Sr, Nd and Os isotopic compositions of peridotite xenoliths and orogenic massif peridotites from the continents of Europe, Asia, America, Africa and Australia, together with previous studies of petrology and geochemistry of global peridotites, we suggest that (1) refertilization of cratonic and circum-cratonic lithospheric mantle is widespread; (2) Archean SCLM worldwide has experienced a multi-stage history of melt depletion and refertilization since segregation from the convecting mantle; (3) cratonic SCLM may be more susceptible to compositional change caused by

  9. Application of multi-dimensional discrimination diagrams and probability calculations to Paleoproterozoic acid rocks from Brazilian cratons and provinces to infer tectonic settings

    NASA Astrophysics Data System (ADS)

    Verma, Sanjeet K.; Oliveira, Elson P.

    2013-08-01

    In present work, we applied two sets of new multi-dimensional geochemical diagrams (Verma et al., 2013) obtained from linear discriminant analysis (LDA) of natural logarithm-transformed ratios of major elements and immobile major and trace elements in acid magmas to decipher plate tectonic settings and corresponding probability estimates for Paleoproterozoic rocks from Amazonian craton, São Francisco craton, São Luís craton, and Borborema province of Brazil. The robustness of LDA minimizes the effects of petrogenetic processes and maximizes the separation among the different tectonic groups. The probability based boundaries further provide a better objective statistical method in comparison to the commonly used subjective method of determining the boundaries by eye judgment. The use of readjusted major element data to 100% on an anhydrous basis from SINCLAS computer program, also helps to minimize the effects of post-emplacement compositional changes and analytical errors on these tectonic discrimination diagrams. Fifteen case studies of acid suites highlighted the application of these diagrams and probability calculations. The first case study on Jamon and Musa granites, Carajás area (Central Amazonian Province, Amazonian craton) shows a collision setting (previously thought anorogenic). A collision setting was clearly inferred for Bom Jardim granite, Xingú area (Central Amazonian Province, Amazonian craton) The third case study on Older São Jorge, Younger São Jorge and Maloquinha granites Tapajós area (Ventuari-Tapajós Province, Amazonian craton) indicated a within-plate setting (previously transitional between volcanic arc and within-plate). We also recognized a within-plate setting for the next three case studies on Aripuanã and Teles Pires granites (SW Amazonian craton), and Pitinga area granites (Mapuera Suite, NW Amazonian craton), which were all previously suggested to have been emplaced in post-collision to within-plate settings. The seventh case

  10. Metasomatism and the Weakening of Cratons: A Mechanism to Rift Cratons

    NASA Astrophysics Data System (ADS)

    Wenker, Stefanie; Beaumont, Christopher

    2016-04-01

    The preservation of cratons is a demonstration of their strength and resistance to deformation. However, several cratons are rifting now (e.g. Tanzania and North China Craton) or have rifted in the past (e.g. North Atlantic Craton). To explain this paradox, we suggest that widespread metasomatism of the originally cold depleted dehydrated craton mantle lithosphere root can act as a potential weakening mechanism. This process, particularly melt metasomatism, increases root density through a melt-peridotite reaction, and reduces root viscosity by increasing the temperature and rehydrating the cratonic mantle lithosphere. Using 2D numerical models, we model silicate-melt metasomatism and rehydration of cold cratonic mantle lithosphere that is positioned beside standard Phanerozoic lithosphere. The models are designed to investigate when a craton is sufficiently weakened to undergo rifting and is no longer protected by the initially weaker adjacent standard Phanerozoic lithosphere. Melt is added to specified layers in the cratonic mantle lithosphere at a uniform volumetric rate determined by the duration of metasomatism (3 Myr, 10 Myr or 30 Myr), until a total of ~30% by volume of melt has been added. During melt addition heat and mass are properly conserved and the density and volume increase by the respective amounts required by the reaction with the peridotite. No extensional boundary conditions are applied to the models during the metasomatism process. As expected, significant refertilization leads to removal and thinning of progressively more gravitationally unstable cratonic mantle lithosphere. We show that the duration of metasomatism dictates the final temperature in the cratonic upper mantle lithosphere. Consequently, when extensional boundary conditions are applied in our rifting tests in most cases the Phanerozoic lithosphere rifts. The craton rifts only in the models with the hottest cratonic upper mantle lithosphere. Our results indicate rifting of cratons

  11. The metropolitan area of Sao Paulo, Brazil.

    PubMed

    Hakkert, R; Gondo, C T

    1984-08-01

    This discussion of the metropolitan area of Sao Paulo, Brazil focuses on: administrative divisions; diversity and population growth; households, fertility, and mortality; migration; ethnicity, race, and religion; housing; transport; labor and income; and consumption. Currently, the metropolitan area of Sao Paulo, or Greater Sao Paula, is considered the 2nd largest urban agglomeration in Latin America after Mexico City. An estimated 9.5 million people live within the 583 square mile area of the central city. Another 5 million people live in 1 of the 36 other municipalities included in the metropolitan area which includes all 37 municipalities. Central city refers to the municipalities of Sao Paulo and Osasco. The city of Sao Paulo refers only to the municipality of Sao Paulo. The metropolitan area contains 3110 square miles in total and is still the smallest of the 11 administrative regions that comprise the State of Sao Paulo. The population, urban infrastructure, and economic activities are unevenly spread among the 37 municipalities. Greater Sao Paulo's population grew an average of 4.5 year during the 1970, down slightly from a peak of 5.9 year in the 1950s. The central city has a current growth rate of 3.7, a year, with the increase concentrated mainly in the southern and eastern districts that are removed from the city center and where land prices are still relatively low. Mortality plays a minor role in the population trends of Sao Paulo. Fertility is now slowly becoming the dominant factors in its natural increase. The average number of children a woman will bear is 3.3 in the metropolitan area and 3 in the city, low compared with the Brazilian national average of 4.2 children. According to a 1978 survey, 60% of the women use some form of birth control. The most common methods are oral contraceptives 27%, and sterilization, 15%. Despite declining fertility, the birthrate of the metropolitan area increased from 26 in 1970 to 30 in 1980 because of the changes

  12. Plume-induced cratonization in Archean Earth

    NASA Astrophysics Data System (ADS)

    Gerya, T.; Sizova, E.; Bogdanova, S. V.; Tackley, P.

    2016-12-01

    Cratons are the oldest stabilized parts of Earth's continents that have multi-stage history and are characterized by thick heterogeneous (on the scale of tens to hundreds km) mantle roots with variable degree of depletion and metasomatic reworking. Several distinct proto-cratonic units of hundreds km size differing in crustal and mantle structure could be often found within large cratons. Geodynamic mechanisms of cratons formation remain debatable and combine both plate-tectonics-related and plume-related processes. Based on recent numerical experiments, we propose a new concept of Archean cratonization intrinsically related to the operation of plume-lid tectonics by which proto-continental and proto-oceanic lithospheric domains spontaneously formed before the onset of global plate tectonics. In contrast to present day, hot felsic proto-continental domains had thinner, more deformable and less depleted mantle lithosphere compared to their cold mafic proto-oceanic counterparts formed by ultraslow spreading atop hot mantle upwellings. Numerical models show feasibility of short-lived deep subduction of the depleted proto-oceanic lithosphere to core-mantle boundary driven by eclogitization of the thick mafic crust. Subsequent heating and buoyancy-driven separation of the eclogite and harzburgite triggered formation of strongly depleted harzburgite plumes. Rising and accretion of these chemically buoyant refractory plumes to the bottom of proto-continental domains created relatively small (hundreds km) proto-cratons. After onset of global plate tectonics, assembling of smaller proto-cratonic terrains formed actual large cratons.

  13. Origin and evolution of the Amazonian craton

    NASA Technical Reports Server (NTRS)

    Gibbs, A. K.; Wirth, K. R.

    1986-01-01

    The Amazonian craton appears to be formed and modifed by processes much like those of the better-known Precambrian cratons, but the major events did not always follow conventional sequences nor did they occur synchronously with those of other cratons. Much of the craton's Archean style continental crust formation, recorded in granite-greenstone and high-grade terranes, occurred in the Early Proterozoic: a period of relative quiescence in many other Precambrian regions. The common Archean to Proterozoic transition in geological style did not occur here, but an analogous change from abundant marine volcanism to dominantly continental sedimentary and eruptive styles occurred later. Amazonian geology is summarized, explaining the evolution of the craton.

  14. Speculations on the formation of cratons and cratonic basins

    NASA Astrophysics Data System (ADS)

    McKenzie, Dan; Priestley, Keith

    2016-02-01

    Surface wave tomography using Rayleigh waves has shown that Tibet and the surrounding mountain ranges that are now being shortened are underlain by thick lithosphere, of similar thickness to that beneath cratons. Both their elevation and lithospheric thickness can result from pure shear shortening of normal thickness continental lithosphere by about a factor of two. The resulting thermal evolution of the crust and lithosphere is dominated by radioactive decay in the crust. It raises the temperature of the lower part of the crust and of the upper part of the lithosphere to above their solidus temperatures, generating granites and small volumes of mafic alkaline rocks from beneath the Moho, as well as generating high temperature metamorphic assemblages in the crust. Thermal models of this process show that it can match the P, T estimates determined from metamorphic xenoliths from Tibet and the Pamirs, and can also match the compositions of the alkaline rocks. The seismological properties of the upper part of the lithosphere beneath northern Tibet suggest that it has already been heated by the blanketing effect and radioactivity of the thick crust on top. If the crustal thickness is reduced by erosion alone to its normal value at low elevations, without any tectonic extension, over a time scale that is short compared to the thermal time constant of thick lithosphere, of ∼250 Ma, thermal subsidence will produce a basin underlain by thick lithosphere. Though this simple model accounts for the relevant observations, there is not yet sufficient information available to be able to model in detail the resulting thermal evolution of the sediments deposited in such cratonic basins.

  15. The SAO {AXAF} Simulation System

    NASA Astrophysics Data System (ADS)

    Jerius, D.; Freeman, M.; Gaetz, T.; Hughes, J. P.; Podgorski, W.

    As part of our efforts to support the AXAF program, the SAO AXAF Mission Support Team has developed a software suite to simulate the AXAF telescope. The software traces the fate of photons through the telescope, from the X-ray source through apertures, baffles, the telescope optics, and finally to the photons' ultimate interactions with the focal plane detectors. We model relevant physical processes, including geometrical reflection, scattering due to surface microroughness, distortions of the optics due to the mirror mounts, attenuation through baffles, etc. The software is composed of programs and scripts, each specialized to a given task, which communicate through UNIX pipes. Software tasks are centered about functional components of the telescope (e.g., apertures, mirrors, detectors) and provide a comfortable and flexible paradigm for performing simulations. The use of separate programs and the UNIX pipe facility allows great flexibility in building different configurations of the telescope and distilling diagnostics from the photon stream through the telescope. We are able to transparently use symmetric multi-processing (e.g., SPARCStation 10s and SGI Challenges) and can easily use sequential multi-processing (via workstation clusters). Some of the tasks are amenable to parallel processing and have been implemented using the MPI standard.

  16. Craton destruction by subduction, collision or plume impingement? Comparisons of some representative cratons in the world

    NASA Astrophysics Data System (ADS)

    Wang, Zhensheng; Kusky, Timothy; Li, Xiaoyong; Wang, Xu; Fu, Jianmin; Yuan, Yuefeng; Zhu, Peimin

    2015-04-01

    The fact that cratonic lithosphere can be destructed has been demonstrated by numerous studies. However, the driving force of craton destruction and its mechanism are still unclear1,2. Subduction, collision and mantle plumes, the most important driving forces for most geological events, may also be responsible for craton destruction. However, their relationship in the destruction process including which of them is the major driving force and how they interact with each other is not understood sufficiently1,2. In this article, the North China Craton, North Atlantic Craton, Tanzania Craton, Wyoming Craton, Kaapvaal Craton, Yangtze Craton, Yilgarn Craton and Superior Craton are used as examples to study their difference and similarities during subduction, collision, or mantle plume impingement. The work is mainly based on comparison of their tectonic history, geophysical data, as well as xenolith chronology. It is suggested that large-scale craton destruction can be influenced by the interaction of subduction, collision and mantle plumes, acting to different degrees in different examples. Mantle plume related thermal action enhances the chemical stratification or layering of subcontinental lithospheric mantle (SCLM), which can form a weak-coupling mid lithosphere discontinuity (MLD) 3,4,5 and a lower denser SCLM below the MLD. Convergence (subduction and collision), especially when associated with slab rollback 6, leads to the regional thinning of the cratonic margin, which is subsequently linked by extension (mantle plume or slab rollback) related discontinuities. Continuous extension-related discontinuities extend upward to the MLD depth and cut off the shearing resistance from adjacent blocks. Next, the lower part of the chemically stratified SCLM in the cratonic interior is decoupled along the weakly coupled MLD and founders into the deep asthenosphere 7. Then the destruction of the rest of the lithosphere can be affected by upwelling related decompression melting

  17. LibKiSAO: a Java library for Querying KiSAO.

    PubMed

    Zhukova, Anna; Adams, Richard; Laibe, Camille; Le Novère, Nicolas

    2012-09-24

    The Kinetic Simulation Algorithm Ontology (KiSAO) supplies information about existing algorithms available for the simulation of Systems Biology models, their characteristics, parameters and inter-relationships. KiSAO enables the unambiguous identification of algorithms from simulation descriptions. Information about analogous methods having similar characteristics and about algorithm parameters incorporated into KiSAO is desirable for simulation tools. To retrieve this information programmatically an application programming interface (API) for KiSAO is needed. We developed libKiSAO, a Java library to enable querying of the KiSA Ontology. It implements methods to retrieve information about simulation algorithms stored in KiSAO, their characteristics and parameters, and methods to query the algorithm hierarchy and search for similar algorithms providing comparable results for the same simulation set-up. Using libKiSAO, simulation tools can make logical inferences based on this knowledge and choose the most appropriate algorithm to perform a simulation. LibKiSAO also enables simulation tools to handle a wider range of simulation descriptions by determining which of the available methods are similar and can be used instead of the one indicated in the simulation description if that one is not implemented. LibKiSAO enables Java applications to easily access information about simulation algorithms, their characteristics and parameters stored in the OWL-encoded Kinetic Simulation Algorithm Ontology. LibKiSAO can be used by simulation description editors and simulation tools to improve reproducibility of computational simulation tasks and facilitate model re-use.

  18. Ambient Noise Imaging of Craton Modification: Examples from the Kaapvaal craton

    NASA Astrophysics Data System (ADS)

    Porter, R. C.; Shirey, S. B.; Fouch, M. J.; James, D. E.

    2013-12-01

    Mapping of crustal and upper-mantle seismic velocities can give important insight into the geologic evolution of cratonic regions. In order to better understand the formation and evolution of the Kaapvaal craton and surrounding regions, we use ambient noise tomography to produce a new crustal and upper-mantle 3D shear-velocity model for southeastern Africa using data collected during the (1995-1999) Kaapvaal Seismic Experiment. Ambient noise tomography enables imaging of shear-velocity variations at smaller scales (10s of km) and shallower depths (< 10 km) than previously determined using natural-source body- and surface-wave techniques within the region. The goal of this work is to image geological features of the Kaapvaal-Zimbabwe craton such as kimberlite pipe density, flood basalt feeder dike systems, granite-greenstone belts, layered mafic intrusions and craton assembly/collision patterns at mid- lower crustal levels where information is typically lacking. Our results provide important constraints on the evolution of the Kaapvaal craton, including the collision with the Zimbabwe craton and the formation of the Bushveld Complex and Witwatersrand basin, and the impact of these events on lithospheric structure. Preliminary images exhibit key first-order features of the craton. At depth ranges of 4-12 km, reduced shear velocities correlate with the Bushveld-Malopo Farms complexes. At a depth interval of 10-18 km, lower velocities are associated with the Witwatersrand sedimentary basin, and higher velocities may be attributed to unroofed mid-crustal rocks of high metamorphic grade formed during the Kaapvaal-Zimbabwe craton collision. At depths of 36-46 km, velocity patterns reflect Moho topography, with thinner crust associated with the undisturbed regions of the Kaapvaal and Zimbabwe cratons and thicker crust associated with the Limpopo Belt and Namaqua-Natal Mobile Belt. At greater depths, higher upper-mantle velocities are observed in the southern Kaapvaal

  19. Destroying a Craton by Plate Subduction, Small-scale Convection, and Mantle Plume: Comparison of the Wyoming Craton and the North China Craton

    NASA Astrophysics Data System (ADS)

    Li, A.; Dave, R.

    2016-12-01

    A typical craton has a thick, strong, and neutrally buoyant lithosphere that protects it from being destructed by mantle convection. The Wyoming craton and the North China craton are two rare representatives, where the thick Archean lithosphere has been significantly thinned and partially removed as revealed in seismic tomography models. The Wyoming craton in the west-central US experienced pervasive deformation 80-55 Ma during the Laramide orogeny. It has been subsequently encroached upon by the Yellowstone hotspot since 2.0 Ma. Recent seismic models agree that the northern cratonic root in eastern Montana has been broadly removed while the thick root is still present in Wyoming. Our radial anisotropy model images a VSV>VSH anomaly associated with the deep fast anomaly in central Wyoming, indicating mantle downwelling. Continuous low velocities are observed beneath the Yellowstone hotspot and the Cheyenne belt at the craton's southern margin, suggesting mantle upwelling in the sub-lithosphere mantle. These observations evidence for small-scale mantle convection beneath the south-central Wyoming craton, which probably has been actively eroding the cratonic lithosphere. The small-scale mantle convection is probably also responsible for the observed, localized lithosphere delamination beneath the eastern North China craton. In addition, a plume-like, low-velocity feature is imaged beneath the central block of the North China craton and is suggested as the driving force for destructing the cratonic root. Like the Wyoming craton that was subducted by the Farallon plate during the Laramide orogeny, the North China craton was underlined by the ancient Pacific plate before the root destruction in Late Jurassic. In both cases, the subducted slab helped to hydrate and weaken the cratonic lithosphere above it, initiate local metasomatism and partial melting, and promote small-scale convection. The craton's interaction with a mantle plume could further strengthen the small

  20. Cratonic lithosphere: an electrifying view (Invited)

    NASA Astrophysics Data System (ADS)

    Jones, A. G.

    2013-12-01

    Deep-probing electromagnetic studies reveal the vertical and lateral electrical conductivity structure of cratonic lithosphere. At lithospheric temperatures and for silicate mantle minerals, semi-conduction is from small polaron hopping and, in the presence of water, proton conduction, both of which is thermally-driven and can be described by an Arrhenius equation. There is little compositional sensitivity, save for the far higher water contents prevalent in pyroxenes (typically 200-400 wt ppm) compared to olivine (typically 10-100 wt ppm), with the latter exhibiting a depth dependence and the former none. Seismological methods are sensitive to temperature and composition, and virtually insensitive to low amounts of water. Taken together, the two are highly complementary. Seismological and magnetotelluric studies across Southern Africa can be employed together to constraint temperature and water content, where there is a significant difference at 100 km depth between the Kaapvaal Craton compared to the Angola (Congo) Craton compared to the Zimbabwe Craton. The Congo Craton is driest but hottest, the Kaapvaal Craton exhibits laterally-varying water content and is coldest, and the Zimbabwe Craton is the wettest and intermediate in temperature. Such thermal and water content variation results in lateral rheological variation, with the wettest and warmest being more deformable. For the Canadian Shield, there is again significant lateral variation at 100 km, with the Superior Province being mostly dry, and the Slave Craton and Rae/Hearne Provinces being far wetter. By 200 km however, all of the Canadian Shield is dry, consistent with the xenolith-based observations from the Kaapvaal Craton of far higher water contents in olivine at 100 km (50-100 wt ppm) decreasing with depth to around 10 wt ppm at 200 km. The lithosphere beneath the Kimberley area of the Kaapvaal Craton has been forward modeled in a manner that is self-consistent not only with the seismological and

  1. Network and Data Bank at SAO

    NASA Astrophysics Data System (ADS)

    Vitkovskij, V.

    1997-03-01

    This paper gives an outline of the main principles and architecture for networking, telecommunication and data access at the Special Astrophysical Observatory (SAO). Its second goal is to give a view of the state and trends of computing, networking and data archiving. A combined satellite/microwave/fiberoptic link is the basis of the network. The microwave and fiberoptic (in future) links are used for the SAO local loops (three LANs). The satellite link (64 K) connects the SAOnet with Internet via DESY (Germany) and MSU (Russia). The basic TCP/IP services, consisting of file transfer (FTP), e-mail and terminal access (including TELNET and X-Windows) are available everywhere on the network. Telecommunication services enable SAO scientists and their partners to exchange data rapidly and to pursue successfully collaborative projects.

  2. HD-SAO-DM cross index

    NASA Technical Reports Server (NTRS)

    Nagy, T. A.; Mead, J.

    1978-01-01

    A table of correspondence SAO-HD-DM-GC was prepared by Morin (1973). The machine-readable version of this cross identification was obtained from the Centre de Donnees Stellaires (Strasbourg, France). The table was sorted at the Goddard Space Flight Center by HD number and all blank HD number records were removed to produce the HD-SAO-DM table presented. There were 258997 entries in the original table; there are 180411 entries after removing the blank HD records. The Boss General Catalogue (GC) numbers were retained on the machine-readable version after the sort.

  3. Water in the Cratonic Mantle Lithosphere

    NASA Technical Reports Server (NTRS)

    Peslier, A. H.

    2016-01-01

    The fact that Archean and Proterozoic cratons are underlain by the thickest (>200 km) lithosphere on Earth has always puzzled scientists because the dynamic convection of the surrounding asthenosphere would be expected to delaminate and erode these mantle lithospheric "keels" over time. Although density and temperature of the cratonic lithosphere certainly play a role in its strength and longevity, the role of water has only been recently addressed with data on actual mantle samples. Water in mantle lithologies (primarily peridotites and pyroxenites) is mainly stored in nominally anhydrous minerals (olivine, pyroxene, garnet) where it is incorporated as hydrogen bonded to structural oxygen in lattice defects. The property of hydrolytic weakening of olivine [4] has generated the hypothesis that olivine, the main mineral of the upper mantle, may be dehydrated in cratonic mantle lithospheres, contributing to its strength. This presentation will review the distribution of water concentrations in four cratonic lithospheres. The distribution of water contents in olivine from peridotite xenoliths found in kimberlites is different in each craton (Figure 1). The range of water contents of olivine, pyroxene and garnet at each xenolith location appears linked to local metasomatic events, some of which occurred later then the Archean and Proterozoic when these peridotites initially formed via melting. Although the low olivine water contents (<10 ppm wt H2O) at > 6 GPa at the base of the Kaapvaal cratonic lithosphere may contribute to its strength, and prevent its delamination, the wide range of those from Siberian xenoliths is not compatible with providing a high enough viscosity contrast with the asthenophere. The water content in olivine inclusions from Siberian diamonds, on the other hand, have systematically low water contents (<20 ppm wt H2O). The xenoliths may represent a biased sample of the cratonic lithosphere with an over-­abundance of metasomatized peridotites with

  4. Greater Sao Paulo Newer Library Automation.

    ERIC Educational Resources Information Center

    McLean, Dulce Didio

    1991-01-01

    This followup to a 1981 study presents descriptions of automated projects or activities in academic, public, and special libraries or information centers in the Greater Sao Paulo region that developed from 1981 through 1987. It is noted that an overall increase in the level of automation since 1981 has been observed. (four references) (Author/MAB)

  5. Greater Sao Paulo Newer Library Automation.

    ERIC Educational Resources Information Center

    McLean, Dulce Didio

    1991-01-01

    This followup to a 1981 study presents descriptions of automated projects or activities in academic, public, and special libraries or information centers in the Greater Sao Paulo region that developed from 1981 through 1987. It is noted that an overall increase in the level of automation since 1981 has been observed. (four references) (Author/MAB)

  6. Kimberlites of the Man craton, West Africa

    NASA Astrophysics Data System (ADS)

    Skinner, E. M. W.; Apter, D. B.; Morelli, C.; Smithson, N. K.

    2004-09-01

    The Man craton in West Africa is an Archaean craton formerly joined to the Guyana craton (South America) that was rifted apart in the Mesozoic. Kimberlites of the Man craton include three Jurassic-aged clusters in Guinea, two Jurassic-aged clusters in Sierra Leone, and in Liberia two clusters of unknown age and one Neoproterozoic cluster recently dated at ˜800 Ma. All of the kimberlites irrespective of age occur as small pipes and prolific dykes. Some of the Banankoro cluster pipes in Guinea, the Koidu pipes in Sierra Leone and small pipes in the Weasua cluster in Liberia contain hypabyssal-facies kimberlite and remnants of the so-called transitional-facies and diatreme-facies kimberlite. Most of the Man craton kimberlites are mineralogically classified as phlogopite kimberlites, although potassium contents are relatively low. They are chemically similar to mica-poor Group 1A Southern African examples. The Jurassic kimberlites are considered to represent one province of kimberlites that track from older bodies in Guinea (Droujba 153 Ma) to progressively younger kimberlites in Sierra Leone (Koidu, 146 Ma and Tongo, 140 Ma). The scarcity of diatreme-facies kimberlites relative to hypabyssal-facies kimberlites and the presence of the so-called transitional-facies indicate that the pipes have been eroded down to the interface between the root and diatreme zones. From this observation, it is concluded that extensive erosion (1-2 km) has occurred since the Jurassic. In addition to erosion, the presence of abundant early crystallizing phlogopite is considered to have had an effect on the relatively small sizes of the Man craton kimberlites.

  7. Manuel francisco allende

    PubMed

    Thivolet

    2000-06-01

    It was on the occasion of my first visit to San Francisco that I got to know Manuel Frank Allende. He was born in Uruguay in 1918 but spent time in Paris where he worked as a hospital registrar shortly before the war. In 1940, he saw the occupation of France by the Germans. He passed over the Spanish border, was briefly interned and then set off back to the United States. He had a brief "stay" at Ellis Island opposite Manhattan, before obtaining a resident's permit enabling him to continue his speciality, dermatology. He then left for California, his wife, Katharine's home state. Manuel Frank was very open-minded, benefiting from the Spanish, French and American cultures, a "man of the world" before the term had been invented. We soon got on well, he liked skiing, which he had practised in Alpe d'Huez before the war. I visited him in San Francisco where he lived in a house dominating the Bay near the Golden Gate. He drew and painted the wonderful view he had from his windows. He died suddenly on the slopes in the Rocky Mountains. Katharine still lives in San Francisco where she has long been a member of the governing body of the French hospital. Manuel Frank left a marvellous collection of drawings which illustrate well the kind of man he was.

  8. Cyclic Cratonic Carbonates and Phanerozoic Calcite Seas.

    ERIC Educational Resources Information Center

    Wilkinson, Bruce H.

    1982-01-01

    Discusses causes of cyclicity in cratonic carbonate sequences and evidence for and potential significance of postulated primary calcite sediment components in past Paleozoic seas, outlining problems, focusing on models explaining existing data, and identifying background. Future sedimentary geologists will need to address these and related areas…

  9. Cyclic Cratonic Carbonates and Phanerozoic Calcite Seas.

    ERIC Educational Resources Information Center

    Wilkinson, Bruce H.

    1982-01-01

    Discusses causes of cyclicity in cratonic carbonate sequences and evidence for and potential significance of postulated primary calcite sediment components in past Paleozoic seas, outlining problems, focusing on models explaining existing data, and identifying background. Future sedimentary geologists will need to address these and related areas…

  10. Lithospheric growth at margins of cratons

    NASA Astrophysics Data System (ADS)

    Snyder, D. B.

    2002-09-01

    Deep seismic reflection profiles collected across Proterozoic-Archean margins are now sufficiently numerous to formulate a consistent hypothesis of how continental nuclei grow laterally to form cratonic shields. This picture is made possible both because the length of these regional profiles spans all the tectonic elements of an orogen on a particular cratonic margin and because of their great depth range. Key transects studied include the LITHOPROBE SNORCLE 1 transect and the BABEL survey, crossing the Slave and Baltic craton margins, respectively. In most cases, the older (Archean) block appears to form a wedge of uppermost mantle rock embedded into the more juvenile (Proterozoic) block by as much as 100-200 km at uppermost mantle depths and Archean lithosphere is therefore more laterally extensive at depth than at the surface. Particularly bright reflections along the Moho are cited as evidence of shear strain within a weak, low-viscosity lower crustal channel that lies along the irregular top of the indenting wedge. The bottom of the wedge is an underthrust/subduction zone, and associated late reversal in subduction polarity beneath the craton margin emerges as a common characteristic of these margins although related arc magmatism may be minor.

  11. Phanerozoic surface history of the Slave craton

    NASA Astrophysics Data System (ADS)

    Ault, Alexis K.; Flowers, Rebecca M.; Bowring, Samuel A.

    2013-09-01

    apatite (U-Th)/He (AHe) thermochronometry data and key geologic constraints from Slave craton kimberlites are used to develop a model for the Phanerozoic burial, unroofing, and hypsometric history of the northwestern Canadian shield. AHe dates range from 210 ± 13 to 382 ± 79 Ma, are older in the eastern Slave craton and decrease westward, and resolve the spatial extent, thickness, and history of now-denuded sedimentary units. Results indicate Paleozoic heating to temperatures ≥85-90°C, suggesting regional burial beneath ≥2.8 km of strata while the region was at sea level, followed by the westward migration of unroofing across the craton. This Paleozoic-Mesozoic history does not correlate with sea level change, instead requiring Paleozoic subsidence of the craton followed by surface uplift. The AHe data restrict Cretaceous burial to ≤1.6 km, followed by unroofing, Eocene terrestrial sediment deposition, and removal of Phanerozoic sedimentary cover across the region by present day. The craton underwent ≥300 m of post-100 Ma elevation gain, based on ~100 Ma marine sedimentary xenoliths entrained in ~75-45 Ma kimberlites at modern elevations of 550-600 m. The transition from Paleozoic-Mesozoic subsidence to surface uplift may signal a change from predominantly northern (Franklinian-Innuitian) to western (Canadian Cordillera) plate boundary controls on continental interior processes, with the latter driving the east-to-west wave of unroofing. Canadian Cordillera evolution also affected the Cretaceous-early Tertiary history. Dynamic topography due to changing mantle flow regimes and proximity to sediment sources influenced the Phanerozoic surface evolution of the northwestern Canadian shield.

  12. The electrical structure of the Slave craton

    NASA Astrophysics Data System (ADS)

    Jones, Alan G.; Lezaeta, Pamela; Ferguson, Ian J.; Chave, Alan D.; Evans, Rob L.; Garcia, Xavier; Spratt, Jessica

    2003-12-01

    The Slave craton in northwestern Canada, a relatively small Archean craton (600×400 km), is ideal as a natural laboratory for investigating the formation and evolution of Mesoarchean and Neoarchean sub-continental lithospheric mantle (SCLM). Excellent outcrop and the discovery of economic diamondiferous kimberlite pipes in the centre of the craton during the early 1990s have led to an unparalleled amount of geoscientific information becoming available. Over the last 5 years deep-probing electromagnetic surveys were conducted on the Slave, using the natural-source magnetotelluric (MT) technique, as part of a variety of programs to study the craton and determine its regional-scale electrical structure. Two of the four types of surveys involved novel MT data acquisition; one through frozen lakes along ice roads during winter, and the second using ocean-bottom MT instrumentation deployed from float planes. The primary initial objective of the MT surveys was to determine the geometry of the topography of the lithosphere-asthenosphere boundary (LAB) across the Slave craton. However, the MT responses revealed, completely serendipitously, a remarkable anomaly in electrical conductivity in the SCLM of the central Slave craton. This Central Slave Mantle Conductor (CSMC) anomaly is modelled as a localized region of low resistivity (10-15 Ω m) beginning at depths of ˜80-120 km and striking NE-SW. Where precisely located, it is spatially coincident with the Eocene-aged kimberlite field in the central part of the craton (the so-called "Corridor of Hope"), and also with a geochemically defined ultra-depleted harzburgitic layer interpreted as oceanic or arc-related lithosphere emplaced during early tectonism. The CSMC lies wholly within the NE-SW striking central zone defined by Grütter et al. [Grütter, H.S., Apter, D.B., Kong, J., 1999. Crust-mantle coupling; evidence from mantle-derived xenocrystic garnets. Contributed paper at: The 7th International Kimberlite Conference

  13. Lithospheric layering in the North American craton.

    PubMed

    Yuan, Huaiyu; Romanowicz, Barbara

    2010-08-26

    How cratons-extremely stable continental areas of the Earth's crust-formed and remained largely unchanged for more than 2,500 million years is much debated. Recent studies of seismic-wave receiver function data have detected a structural boundary under continental cratons at depths too shallow to be consistent with the lithosphere-asthenosphere boundary, as inferred from seismic tomography and other geophysical studies. Here we show that changes in the direction of azimuthal anisotropy with depth reveal the presence of two distinct lithospheric layers throughout the stable part of the North American continent. The top layer is thick ( approximately 150 km) under the Archaean core and tapers out on the surrounding Palaeozoic borders. Its thickness variations follow those of a highly depleted layer inferred from thermo-barometric analysis of xenoliths. The lithosphere-asthenosphere boundary is relatively flat (ranging from 180 to 240 km in depth), in agreement with the presence of a thermal conductive root that subsequently formed around the depleted chemical layer. Our findings tie together seismological, geochemical and geodynamical studies of the cratonic lithosphere in North America. They also suggest that the horizon detected in receiver function studies probably corresponds to the sharp mid-lithospheric boundary rather than to the more gradual lithosphere-asthenosphere boundary.

  14. Cratonization: a thermal and petrological perspective

    SciTech Connect

    Pollack, H.N.

    1985-01-01

    The long term thermal and tectonic history of the continental lithosphere derives from the processes that lead to crationization. Cratons are characterized by mechanical stability, buoyancy and freeboard, a paucity of magmatism, and deep roots. The process is not slow and gradual, extending over aeons, but rather is relatively rapid, being accomplished in a period on the order of 300-500 Ma; cratonic nuclei existed by the end of the Archean. The essential process is devolatilization of the upper mantle, in associations with major orogenic events, to a depth of about 300 km. Devolatilization has the following effects: 1) it elevates the solidus of the affected lithosphere, making it less vulnerable to subsequent melting, 2) it augments the mechanical strength and stiffness of the region by increasing the activation energy, thereby 3) enhancing the structural stability of the lithosphere, thickening it, and extending to greater depths the region in which conduction is the principal mode of heat transfer, thereby 4) maintaining freeboard by the thermal expansion of the extended lithosphere because of the higher temperatures of the conductive thermal regime, and 5) enhancement of buoyancy by thermal expansion and petrological differentiation. The process of cratonization can be reversed by reintroduction of volatiles for the deeper mantle, or by raising the temperature sufficiently to reach the volatile-free refractory solidus. Mantle metasomatic processes probably promote destabilization by recharging the thick need lithosphere with both volatiles and heat producing isotopes.

  15. Tracing origins of cratonic eclogites by magnesium isotopes

    NASA Astrophysics Data System (ADS)

    Wang, S.; Teng, F. Z.; Rudnick, R. L.; Li, S. G.

    2014-12-01

    Cratonic eclogites are samples of lithospheric mantle preserved beneath ancient continental cratons. Hence, the origin of cratonic eclogites is closely related to the formation and evolution of cratonic mantle. Here we report Mg isotopic compositions for 27 cratonic eclogites and 52 garnet and clinopyroxene mineral separates from Koidu, Bellsbank and Kaalvallei kimberlite pipes in South and West Africa. Whole-rock Mg isotopic compositions vary widely, with δ26Mg ranging from -1.60 to +0.17, significantly different from the value (δ26Mg = -0.25 ± 0.07) of peridotite xenoliths. Garnet and clinopyroxene in these cratonic eclogites record equilibrium inter-mineral Mg isotope partitioning at mantle temperatures, with Δ26MgCpx-Grt (= δ26MgCpx - δ26MgGrt) in the range of 0.43 - 0.85 ‰. The constructed bulk δ26Mg values based on mineral compositions are identical to the measured whole-rock values, indicating limited influence of kimberlite infiltration on Mg isotopic compositions of cratonic eclogites. As significant Mg isotope fractionation can only occur during low-temperature surface processes, the large Mg isotopic variations of cratonic eclogites suggest the incorporation of subducted materials in their protoliths. Therefore, our Mg isotopic data suggest the cratonic eclogites are the remnants of subducted oceanic crust within the lithospheric mantle. Collectively, Mg isotopes are potentially excellent tracers of the formation and evolution of sub-continental lithospheric mantle.

  16. Shear wave velocity and radial anisotropy beneath the Wyoming craton: craton destruction and lithospheric layering

    NASA Astrophysics Data System (ADS)

    Dave, R.; Li, A.

    2016-12-01

    The Wyoming craton has evolved under an intriguing geological history with suture zones, accreted margins, flat-slab subduction, orogeny and an encroaching hotspot. Whether and how the cratonic root has been widely destroyed by the series of tectonic events remain controversial. Aiming to address these questions using a craton-wide model, we have analyzed Rayleigh and Love wave data from 75 earthquakes recorded by 103 USArray TA stations in the Wyoming craton. 2-D phase velocity maps are constructed for 18 periods from 20 s to 166 s using the two-plane-wave tomography. The Yellowstone hotspot and the Cheyenne belt are characterized by low velocity anomalies at all periods in both Rayleigh and Love wave models. The northern craton in Montana is broadly fast at periods < 70 s and is relatively slow at longer periods, suggesting a shallower lithosphere. The fast anomaly in Wyoming has a NE-SW trend and extends to more than 200 km in the VSV model. However, such a fast anomaly is largely absent in the Love wave images at long periods. The association of VSV>VSH with this deep fast anomaly indicates mantle downwelling beneath south-central Wyoming. Mantle upwelling likely happens in slow regions at the hotspot, the Cheyenne belt, and the northeastern craton. The overall pattern of velocity anomaly and radial anisotropy suggests that small-scale mantle convection is vigorously acting beneath the Wyoming craton and continuously destructing the cratonic lithosphere. In addition, the average VSV and VSH models show a strong positive radial anisotropy of 5% (VSH>VSV) above 100 km and a weak negative anisotropy (VSV>VSH) below 120 km. Such a significant change in radial anisotropy could contribute to the observed mid-lithosphere discontinuity (MLD) from receiver functions. Both VSV and VSH reveal a fast lid above 100 km and a large velocity reduction at the depths of 115-190 km, corresponding with a lithosphere-asthenosphere boundary (LAB) at 150 km. These observations

  17. Jean Parker School, San Francisco.

    ERIC Educational Resources Information Center

    Larson, Soren

    1999-01-01

    Describes the post-earthquake renovation of a San Francisco urban elementary school that preserved its historical detail within a modern replacement. Design features are detailed; photos and a floorplan are included. (GR)

  18. Petrogenesis of Early Cretaceous basaltic lavas from the North China Craton: Implications for cratonic destruction

    NASA Astrophysics Data System (ADS)

    Qian, Sheng-Ping; Ren, Zhong-Yuan; Richard, Wysoczanski; Zhang, Le; Zhang, Yin-Hui; Hong, Lu-Bing; Ding, Xiang-Li; Wu, Ya-Dong

    2017-03-01

    The North China Craton (NCC) is believed to be the best example of cratonic destruction. However, the processes leading to cratonic destruction remain unclear, largely due to a lack of knowledge of the nature of the Mesozoic NCC lithospheric mantle. Here we report new petrological and geochemical data for Early Cretaceous NCC basalts, which provide insights into the nature of the underlying lithospheric mantle. The Early Cretaceous basalts (all tholeiites) show a limited variation in geochemical composition. In contrast, olivine-hosted melt inclusions from these basalts display a wide range in compositional variation and include both alkalic and tholeiitic basaltic compositions. This result provides the direct evidence of the contribution of silica-undersaturated alkali basaltic melts in the petrogenesis of the Early Cretaceous NCC basalts. In addition, the compositions of olivine phenocrysts and reconstructed primary melts indicate that the Early Cretaceous basalts are derived from a mixed peridotite and refertilized peridotite source. The Pb isotopic compositions of melt inclusions in high fugacity of oxygen (fo) olivines combined with trace element characteristics of these basalts reveal that heterogeneous lithospheric mantle sources for Early Cretaceous basalts were metasomatized by carbonate-bearing eclogite-derived melts. The Pb isotopic variations of the melt inclusions and clinopyroxene and plagioclase phenocrysts demonstrate that the mantle-derived magmas were variably contaminated by lower continental crust. We propose that multiple subduction events during the Phanerozoic, combined with mantle-plume activity, likely play a vital role in the generation of the Early Cretaceous voluminous magmatism and cratonic destruction.

  19. Crustal composition of the Western Australian craton and implications for craton formation tectonics

    NASA Astrophysics Data System (ADS)

    Yuan, H.

    2014-12-01

    The Western Australian craton is composed of two Archean blocks, the early-to-mid Archean Pilbara craton and the late Archean Yilgarn craton, and surrounding Proterozoic orogens. Early seismic studies found that these Archean blocks are characterized as a signature type of simple crust and sharp crust-mantle transition, while the orogenic terranes have rather complex crustal structure and much diffused Moho, posing a question whether a possible change in the crustal forming processes occurred between Archean and Proterozoic. Applying receiver functions to available seismic stations, we estimate the bulk crustal thickness and Vp/Vs ratio across the Western Australian craton. The use of the 3D AuSREM velocity models greatly improves the robustness in the bulk crustal property estimates, especially the Vp/Vs ratio that is essential in deriving the crustal composition as well as inferring the tectonic history of individual tectonic units. Our crustal thickness estimates agree well with early studies. The Pilbara crust is uniformly thin (30 km) with a sharp Moho (20% receiver function relative amplitude), and is inferred as extremely felsic in crustal composition (Vp/Vs ratio 1.70, among the lowest in the craton crust globally). The Yilgarn crust is relatively thick (>35km), and is more toward intermediate (Vp/Vs ratio > 1.73). Lateral variations of the Vp/Vs ratios in Yilgarn correlate well with the sub-terranes, reinforcing the early proposal that individual sub-units had gained their unique seismic originality BEFORE the craton amalgamation. Differences between the Pilbara and Yilgarn crust suggest that the vertical and accretional tectonics may have played different roles in forming the cratons. Along the Proterozoic orogens, thicker crust and weaker and possibly dipping Moho interfaces are observed, agreeing with that the regions have been repeatedly reworked. A 20-km thick lower crustal layer with >1.86 Vp/Vs ratio is observed in the Musgrave orogen, reflecting a

  20. Geology of interior cratonic sag basins

    SciTech Connect

    Leighton, M.W.; Eidel, J.J.; Kolata, D.R.; Oltz, D.F. )

    1990-05-01

    Interior cratonic sag basins are thick accumulations of sediment, generally more or less oval in shape, located entirely in the interiors of continental masses. Some are single-cycle basins and others are characterized by repeated sag cycles or are complex polyhistory basins. Many appear to have developed over ancient rift systems. Interior cratonic sag basins are typified by a dominance of flexural over fault-controlled subsidence, and a low ratio of sediment volume to surface area of the basin. The Baltic, Carpentaria, Illinois, Michigan, Parana, Paris, and Williston basins are examples of interior cratonic sag basins. Tectonics played a dominant role in controlling the shapes and the geometries of the juxtaposed packets of sedimentary sequences. While the mechanics of tectonic control are not clear, evidence suggests that the movements are apparently related to convergence of lithospheric plates and collision and breakup of continents. Whatever the cause, tectonic movements controlled the freeboard of continents, altering base level and initiating new tectono-sedimentologic regimes. Sag basins situated in low latitudes during their development commonly were sites of thick carbonates (e.g., Illinois, Michigan, Williston, and Paris basins). In contrast, siliciclastic sedimentation characterized basins that formed in higher latitudes (e.g., Parana and Carpentaria basins). Highly productive sag basins are characterized by widespread, mature, organic-rich source rocks, large structures, and good seals. Nonproductive basins have one or more of the following characteristics: immature source rocks, leaky plumbing, freshwater flushing, and/or complex geology due to numerous intrusions that inhibit mapping of plays.

  1. Host-parasite relationships of monogeneans in gills of Astyanax altiparanae and Rhamdia quelen of the São Francisco Verdadeiro River, Brazil.

    PubMed

    Ferrari-Hoeinghaus, A P; Takemoto, R M; Oliveira, L C; Makrakis, M C; Baumgartner, G

    2006-12-01

    This study investigates the ecology of monogenean gill parasites of Aslyanax altiparanae Garutti & Britski, 2000 and Rhamdia quelen (Quoy & Gaimard, 1824) in a stretch of the Sao Francisco Verdadeiro River, Parana, Brazil. Statistical and ecological indices were used to examine observed levels of parasitism in relation to host and environmental characteristics. A. altiparance and R. quelen had infestation intensities of 2.8 and 23.1 parasites per fish, respectively. The only significant environmental influence was observed at the upstream station for R. quelen. For both host species, parasitized and non-parasitized individuals presented similar weight-ength relationships. Parasitized individuals had dispersed K,, values indicating abnormal conditions. The low levels of parasitism observed in this study suggest that the environment is relatively undisturbed. Additional studies should compare these two species and their respective parasites following completion of the hydroelectric headquarters planned for construction in this stretch of the Sao Francisco Verdoadeiro River.

  2. Mesoproterozoic rapakivi granites of the Rondonia Tin Province, southwestern border of the Amazonian craton, Brazil-I. Reconnaissance U-Pb geochronology and regional implications

    USGS Publications Warehouse

    Bettencourt, Jorge S.; Tosdal, R.M.; Leite, W.B.; Payolla, B.L.

    1999-01-01

    Rapakivi granites and associated mafic and ultramafic rocks in the Rondonia Tin Province, southwestern Amazonian craton, Brazil were emplaced during six discrete episodes of magmatism between ca 1600 and 970 Ma. The seven rapakivi granite suites emplaced at this time were the Serra da Providencia Intrusive Suite (U-Pb ages between 1606 and 1532 Ma); Santo Antonio Intrusive Suite (U-Pb age 1406 Ma); Teotonio Intrusive Suite (U-Pb age 1387 Ma); Alto Candeias Intrusive Suite (U-Pb ages between 1346 and 1338 Ma); Sao Lourenco-Caripunas Intrusive Suite (U-Pb ages between 1314 and 1309 Ma); Santa Clara Intrusive Suite (U-Pb ages between 1082 and 1074 Ma); and Younger Granites of Rondonia (U-Pb ages between 998 and 974 Ma). The Serra da Providencia Intrusive Suite intruded the Paleoproterozoic (1.80 to 1.70 Ga) Rio Negro-Juruena crust whereas the other suites were emplaced into the 1.50 to 1.30 Ga Rondonia-San Ignacio crust. Their intrusion was contemporaneous with orogenic activity in other parts of the southwestern Amazonian craton, except for the oldest, Serra da Providencia Intrusive Suite. Orogenic events coeval with emplacement of the Serra da Providencia Intrusive Suite are not clearly recognized in the region. The Santo Antonio, Teotonio, Alto Candeias and Sao Lourenco-Caripunas Intrusive Suites are interpreted to represent extensional anorogenic magmatism associated with the terminal stages of the Rondonian-San Ignacio orogeny. At least the Sao Lourenco-Caripunas rapakivi granites and coeval intra-continental rift sedimentary rocks may, in contrast, represent the products of extensional tectonics and rifting preceding the Sunsas/Aguapei orogeny (1.25 to 1.0 Ga). The two youngest rapakivi suites, the Santa Clara Intrusive Suite and Younger Granites of Rondonia, seemingly represent inboard magmatism in the Rondonian-San Ignacio Province during a younger episode of reworking in the Rio Negro-Juruena Province during the waning stages of the collisional 1.1 to 1.0 Ga

  3. Overview of buildings with San Francisco skyline in background, looking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Overview of buildings with San Francisco skyline in background, looking 84 degrees east - Presidio of San Francisco, Enlisted Men's Barracks Type, West end of Crissy Field, between Pearce & Maudlin Streets, San Francisco, San Francisco County, CA

  4. 408. Delineator Unknown September 19, 1933 SAN FRANCISCO OAKLAND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    408. Delineator Unknown September 19, 1933 SAN FRANCISCO - OAKLAND BAY BRIDGE; STUDY FOR SAN FRANCISCO ANCHORAGE; TIMOTHY L. PFLUEGER, ARTHUR BROWN JR., JOHN J. DONOVAN; BOARD OF CONSULTING ARCHITECTS; SHEET NO. 26 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  5. 75 FR 39166 - Safety Zone; San Francisco Giants Baseball Game Promotion, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ... Promotion, San Francisco, CA AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast... Bay off San Francisco, CA in support of the San Francisco Giants Baseball Game Promotion. This safety... Giants will sponsor the San Francisco Giants Baseball Game Promotion on July 16, 2010, on the...

  6. 78 FR 18238 - Safety Zone; SFPD Training Safety Zone; San Francisco Bay, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-26

    ... Hunters Point in San Francisco, CA in support of the San Francisco Police Department's maritime... of Homeland Security FR Federal Register SFPD San Francisco Police Department NPRM Notice of Proposed....C sections 1221 et seq.). San Francisco Police Department will host the SFPD Training Safety Zone...

  7. 78 FR 20792 - Safety Zone; San Francisco Giants Fireworks Display, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    ... SECURITY Coast Guard 33 CFR Part 165 Safety Zone; San Francisco Giants Fireworks Display, San Francisco, CA... enforce the safety zone for the San Francisco Giants Fireworks Display in the Captain of the Port, San... (NAD83) for the San Francisco Giants Fireworks Display in 33 CFR 165.1191, Table 1, Item number 1. Under...

  8. 77 FR 28771 - Safety Zone; San Francisco Giants Fireworks Display, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-16

    ... SECURITY Coast Guard 33 CFR Part 165 Safety Zone; San Francisco Giants Fireworks Display, San Francisco, CA... enforce the safety zone for the San Francisco Giants Fireworks Display in the Captain of the Port, San... 46'39.9'' N, 122 23'06.78'' W (NAD83) for the San Francisco Giants Fireworks Display in 33 CFR 165...

  9. Chinatown Chinese: The San Francisco Dialect.

    ERIC Educational Resources Information Center

    Dong, Lorraine; Hom, Marlon K.

    1980-01-01

    Discusses factors that make the language spoken in San Francisco's Chinatown so dynamic and, at times, inconsistent. Provides a glossary that includes transliterated and partially transliterated terms, translated terms, new terms, and special San Francisco terms. (Author/GC)

  10. San Francisco Bay Water Quality Improvement Fund

    EPA Pesticide Factsheets

    EPAs grant program to protect and restore San Francisco Bay. The San Francisco Bay Water Quality Improvement Fund (SFBWQIF) has invested in 58 projects along with 70 partners contributing to restore wetlands, water quality, and reduce polluted runoff.,

  11. The Building of the Archean Superior Craton: Thermal Perspective

    NASA Astrophysics Data System (ADS)

    Jaupart, C. P.; Mareschal, J. C.

    2014-12-01

    The building of a craton involves the extraction of continental crust from the Earth's mantle and the lateral accretion of juvenile volcanic terranes. Ascertaining which conditions allow a newborn continental assemblage to survive requires information on its mechanical strength, which depends on the amount and vertical distribution of radioactive elements in the crust. There is thus a connection between crust formation mechanisms and a successful amalgamation process. To address outstanding questions concerning Archean cratons, the Superior province in Canada is the perfect region because it contains a well preserved geological record of accretion that provides compelling evidence for plate tectonic processes at 2.7 Ga. At almost the same time, the rate of continental growth decreased significantly, which may result from either slower crust formation or enhanced destruction through erosion and subduction. These issues are linked to the strength of the newborn continent. The extensive heat flow data set now available in the Superior Province reveals a clear demarcation between a chemically depleted and differentiated craton core and weakly differentiated enriched juvenile accreted terranes. The Superior craton was thus made of a strong core surrounded by weak terranes. This dichotomy implies that the accretion process could not involve complex imbrication of the accreted belts into the craton core. Subsequently, the craton may have been protected from convective disruption or delamination by its weak margins. Differences between the craton core and accreted terranes may be due to different crustal extraction processes, such as melting in a mantle plume or magmatism in a subduction zone. If subduction started at about 3 Ga, as advocated by several authors, the assembly and survival of large cratons may well be a consequence of this key shift in mantle activity. Alternatively, the chemical depletion of the craton core may be due to a prolonged history of internal

  12. Cratons: Why Are The Little Ones So Tough?

    NASA Astrophysics Data System (ADS)

    Keller, G. R.

    2013-12-01

    Cratons are ancient (>1 Ga) survivors of multiple tectonic events and diverse tectonic regimes. The question that arises is why are they so tough? If one looks around the world at relatively small cratons, the answer at least partly lies in their crustal structure. This is not to say that their lithospheric mantle is not also part of the answer, but mapping the LAB is still a challenge. Some examples of relatively small cratons in North America that are relatively well studied are the Wyoming and SASK cratons. A good example in Africa is the Tanzanian craton, and a good example in China is the North China craton. The Wyoming craton initially formed at ~2.5 Ga and formed has very thick (~50 km) crust that includes a high velocity layer (Vp ~7.5 km/s) at its base. Recent xenolith studies indicate that at least some of this high velocity layer was underplated at ~1.8 Ga. The recently discovered Sask craton in Canada was caught up in the Trans-Hudson orogen and is completely covered by younger rocks. It also has a thick crust. The Tanzanian craton has been strong enough to cause the East African rift system to split into two arms that wrap around it. It has relatively thick crust (and lithospheric keel?). The Colorado plateau in the western U. S. and the Ordos block in north China are very similar in many respects and have resisted deformation in the their interiors while they are bounded on three sides by rifts. A common theme among these examples is relatively thick crust, and in most cases, a unusually fast lower crust.

  13. Redox preconditioning deep cratonic lithosphere for kimberlite genesis - evidence from the central Slave Craton.

    PubMed

    Yaxley, G M; Berry, A J; Rosenthal, A; Woodland, A B; Paterson, D

    2017-12-01

    We present the first oxygen fugacity (fO2) profile through the cratonic lithospheric mantle under the Panda kimberlite (Ekati Diamond Mine) in the Lac de Gras kimberlite field, central Slave Craton, northern Canada. Combining this data with new and existing data from garnet peridotite xenoliths from an almost coeval kimberlite (A154-N) at the nearby Diavik Diamond Mine demonstrates that the oxygen fugacity of the Slave cratonic mantle varies by several orders of magnitude as a function of depth and over short lateral distances. The lower part of the diamond-bearing Slave lithosphere (>120-130 km deep) has been oxidized by up to 4 log units in fO2, and this is clearly linked to metasomatic enrichment. Such coupled enrichment and oxidation was likely caused by infiltrating carbonate-bearing, hydrous, silicate melts in the presence of diamond, a process proposed to be critical for "pre-conditioning" deep lithospheric mantle and rendering it suitable for later generation of kimberlites and other SiO2-undersaturated magmas.

  14. Limiting depth of magnetization in cratonic lithosphere

    NASA Technical Reports Server (NTRS)

    Toft, Paul B.; Haggerty, Stephen E.

    1988-01-01

    Values of magnetic susceptibility and natural remanent magnetization (NRM) of clino-pyroxene-garnet-plagioclase granulite facies lower crustal xenoliths from a kimberlite in west Africa are correlated to bulk geochemistry and specific gravity. Thermomagnetic and alternating-field demagnetization analyses identify magnetite (Mt) and native iron as the dominant magnetic phases (totaling not more than 0.1 vol pct of the rocks) along with subsidiary sulfides. Oxidation states of the granulites are not greater than MW, observed Mt occurs as rims on coarse (about 1 micron) Fe particles, and inferred single domain-pseudosingle domain Mt may be a result of oxidation of fine-grained Fe. The deepest limit of lithospheric ferromagnetism is 95 km, but a limit of 70 km is most reasonable for the West African Craton and for modeling Magsat anomalies over exposed Precambrian shields.

  15. Proterozoic granitoids of the Amazonian craton

    NASA Astrophysics Data System (ADS)

    dalĺAgnol, R.; Costi, H. T.; Lamarão, C. N.; Teixeira, N. P.; Bettencourt, J. S.; Fraga, L. M.

    2003-04-01

    Proterozoic granitoids are widespread in all provinces of the Amazonian craton. In the Maroni-Itacaiunas Province, granitoids associated with the Trans-Amazonian event include: subduction related, 2.16 to 2.14 Ga, calc-alkaline tonalites and trondhjemites; 2.10 to 2.08 Ga, syncolisional potassic granites; 2.05 Ga, charnockites. In the Tapajós Province, ˜2.01 Ga, tonalites are followed by ˜2.0 Ga volcanic sequences and ˜1.98 to 1.96 Ga calc-alkaline granitoids. A reappraisal of magmatic activity occurred at ˜1.88 Ga when calc-alkaline granitoids, as well as subalkaline, A-type granites, associated with felsic volcanic sequences were formed. A similar picture is observed in the northern Roraima region, where post-collisional 2.0 to 1.96 Ga calc-alkaline granitoids and associated volcanic sequences are followed by 1.92 Ga A-type granites. The remarkable 1.88 Ga magmatic event has a continental scale and is related to an extensional tectonism. It affected also the Archean Carajás Province, where, at this time, within-plate, shallow-level, A-type granites were emplaced. Coeval intermediate to felsic volcanic sequences are widespread in the Central Amazonian Province. In the Pitinga region, these sequences are intruded by ˜1.82 Ga, tin-mineralized granites. In the Central Guiana Belt and in the northwestern domains of the Guiana shield ˜1.55 Ga rapakivi complexes, locally with associated anorthosites and mangerites, are common. In the Rio Negro Province, 1.8 to 1.60 calc-alkaline (?) granitoids and gneisses are dominant. They are followed by 1.55 to 1.52 Ga, oxidized, titanite-bearing A-type granites and S-type, two-mica granites. The evolution of the southwestern part of the Amazonian craton is characterized by the occurrence of successive tectonic events extending from ˜1.75 Ga to ˜1.0 Ga. The oldest granitoids are dominantly calc-alkaline tonalites, trondhjemites and granodiorites. However, the Rondonia region is marked by the occurrence of 1.6 to 1.0 Ga old

  16. Seeking Justice in San Francisco

    ERIC Educational Resources Information Center

    Pascopella, Angela

    2010-01-01

    This article discusses the life of Carlos A. Garcia, superintendent at the San Francisco Unified School District. Garcia was born in Chicago, but his parents shortly thereafter moved back to their homeland of Mexico for a few years. When Garcia was almost 5, his family moved to Los Angeles, where his parents worked in factories and Garcia was…

  17. California, San Francisco Bay area

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The San Francisco Bay area (37.5N, 122.0W) of California from the Santa Cruz in the south to Point Reyes in the north with the rich agriculture region of the central San Joaquin Valley in the foreground.

  18. California, San Francisco Bay area

    NASA Image and Video Library

    1981-04-14

    STS001-12-305 (12-14 April 1981) --- California, San Francisco Bay photographed by a crew member on the space shuttle Columbia (STS-1). The coast is seen from near Santa Cruz northward to Point Reyes. The great valley is in the foreground. Photo credit: NASA

  19. Seeking Justice in San Francisco

    ERIC Educational Resources Information Center

    Pascopella, Angela

    2010-01-01

    This article discusses the life of Carlos A. Garcia, superintendent at the San Francisco Unified School District. Garcia was born in Chicago, but his parents shortly thereafter moved back to their homeland of Mexico for a few years. When Garcia was almost 5, his family moved to Los Angeles, where his parents worked in factories and Garcia was…

  20. Origin of cratonic lithospheric mantle roots: A geochemical study of peridotites from the North Atlantic Craton, West Greenland

    NASA Astrophysics Data System (ADS)

    Wittig, N.; Pearson, D. G.; Webb, M.; Ottley, C. J.; Irvine, G. J.; Kopylova, M.; Jensen, S. M.; Nowell, G. M.

    2008-09-01

    A critical examination of the extent to which geodynamic information on the initial mantle depletion and accretion event(s) is preserved in kimberlite-borne cratonic SCLM peridotite xenoliths is attempted by using new major and trace element data of whole-rock peridotites ( n = 55) sampled across the North Atlantic Craton (NAC; West Greenland). We also present additional whole-rock trace element data of mantle xenoliths from Somerset Island, the Slave and Kaapvaal cratons for comparison. Peridotites comprising the West Greenland SCLM are distinctly more olivine-rich and orthopyroxene-poor than most other cratonic peridotites, in particular those from the Kaapvaal craton. The West Greenland peridotites have higher Mg/Si but lower Al/Si, Al 2O 3 and CaO than cratonic mantle from the Kaapvaal Craton. We suggest that the more orthopyroxene depleted, harzburgite to dunite character of the NAC peridotites reflects more of the original melting history than peridotites from other cratons and in that sense may be more typical of cratonic lithosphere compositions prior to extensive modification. Despite this, some modal and cryptic metasomatism has clearly taken place in the West Greenland lithosphere. The insensitivity of major elements to pressure of melting at high degrees of melt extraction combined with the ease with which these elements may be changed by modal metasomatism mean that we cannot confidently constrain the depth of melting of peridotites using this approach. Mildly incompatible trace elements offer much more promise in terms of providing geodynamic information about the original Archean melting regime. The very low, systematically varying heavy REE abundances in NAC whole-rock peridotites and in peridotites from all other cratons where high-quality data are available provide ubiquitous evidence for a shallow melting regime in the absence of, or to the exhaustion of garnet. This finding explicitly excludes large extents of deep (iso- and polybaric) melting

  1. Late Precambrian aulacogens of the North China craton

    NASA Technical Reports Server (NTRS)

    Qian, X.

    1985-01-01

    According to tectonic styles, the Precambrian evolution history of the North China craton may be subdivided into four stages: (1) Archean consolidation in 3.5 to 2.5 Ga, (2) Early Proterozoic rifting in 2.5 to 1.8 Ga, (3) Late Precambrian aulacogen in 1.8 to 0.8 Ga and (4) Platform regime after 0.8 Ga. In the Late Precambrian aulacogen stage of the North China craton there were two main aulacogens, Yanliao and Zhongtiao (Y and Z), developed in Middle Proterozoic time with an age 1.8 to 1.0 Ga. Their NE trend caused them to meet together in the central part of the craton and build up one great Y-Z aulacogen throughout the craton.

  2. Geological evolution of the Antongil Craton, NE Madagascar

    USGS Publications Warehouse

    Schofield, D.I.; Thomas, Ronald J.; Goodenough, K.M.; De Waele, B.; Pitfield, P.E.J.; Key, R.M.; Bauer, W.; Walsh, G.J.; Lidke, D.J.; Ralison, A.V.; Rabarimanana, M.; Rafahatelo, J.-M.; Randriamananjara, T.

    2010-01-01

    The Antongil Craton, along with the Masora and Antananarivo cratons, make up the fundamental Archaean building blocks of the island of Madagascar. They were juxtaposed during the late-Neoproterozoic to early Palaeozoic assembly of Gondwana. In this paper we give a synthesis of the geology of the Antongil Craton and present previously published and new geochemical and U-Pb zircon analyses to provide an event history for its evolution.The oldest rocks in the Antongil Craton form a nucleus of tonalitic gneiss, characteristic of Palaeo-Mesoarchaean cratons globally, including phases dated between 3320 ?? 14. Ma to 3231 ?? 6. Ma and 3187 ?? 2. Ma to 3154 ?? 5. Ma. A series of mafic dykes was intruded into the Mesoarchaean tonalites and a sedimentary succession was deposited on the craton prior to pervasive deformation and migmatisation of the region. The age of deposition of the metasediments has been constrained from a volcanic horizon to around 3178 ?? 2. Ma and subject to migmatisation at around 2597 ?? 49. Ma. A subsequent magmatic episode generated voluminous, weakly foliated granitic rocks, that also included additions from both reworked older crustal material and younger source components. An earlier granodiorite-dominated assemblage, dated between 2570 ?? 18. Ma and 2542 ?? 5. Ma, is largely exposed in xenoliths and more continuously in the northern part of the craton, while a later monzogranite-dominated phase, dated between 2531 ?? 13. Ma and 2513 ?? 0.4. Ma is more widely developed. Together these record the stabilisation of the craton, attested to by the intrusion of a younger dyke swarm, the age of which is constrained by a sample of metagabbro dated at 2147 ?? 6. Ma, providing the first evidence for Palaeoproterozoic rocks from the Antongil Craton.The youngest events recorded in the isotopic record of the Antongil Craton are reflected in metamorphism, neocrystallisation and Pb-loss at 792 ?? 130. Ma to 763 ?? 13. Ma and 553 ?? 68. Ma. These events are

  3. The Thermal Structure and Strength of Cratons and their Margins

    NASA Astrophysics Data System (ADS)

    Jaupart, C. P.; Mareschal, J. C.

    2015-12-01

    The large cratons of today are made of younger terranes that wrap around older cores. Deformation due to accretion did not proceed in homogeneous fashion and was concentrated in the younger belts. This is illustrated clearly in the Archean Superior Province, Canada. In this area, one observes little imbrication of accreted crust and craton core, in contrast to the laterally extensive thrusting that has affected the younger terranes to the South. The boundary between the craton core and accreted belts is a nearly vertical interface delineated by steeply dipping electrical and seismic anomalies extending to the base of the lithosphere. These steeply dipping structures have been interpreted as relicts of the subduction that drove accretion. By contrast, the sub-crustal subduction remnant that is imaged beneath younger terranes to the south shows up as a moderately dipping (≈30°) structure. These observations suggest a stiff craton surrounded by weaker belts. This strength contrast may have affected later events, such as the Keweenawan rifing, which propagated northward through the accreted terranes but stopped short of impinging the craton core. In the Superior Province, crustal heat production is much higher in the accreted terranes than in the craton core, implying higher temperatures and lower mechanical strength. Such a remarkable dichotomy also exists in South Africa, where the Limpopo and Namaqua belts are characterized by higher heat flux and crustal heat production than the adjacent Archean Kaapvaal and Zimbabwe cratons. The generality of this cannot be assessed on the basis of heat flow and heat production data which are scarce in most other cratons. These cratons, however, are characterized by post-orogenic high temperature metamorphism which is best explained by high crustal heat production. This is true, for example, for the Jimperding metamorphic belt at the edge of the Yilgarn craton, Western Australia. Thus, cratons appear to be surrounded, and

  4. Construction and destruction of some North American cratons

    NASA Astrophysics Data System (ADS)

    Snyder, D. B.; Humphreys, G.

    2015-12-01

    Construction histories of Archean cratons remain poorly understood; their destruction is even less clear because of, by definition, its rarity. By assembling geophysical and geochemical data in 3-D lithosphere models, a clearer understanding of the geometry of major structures within the Rae, Slave and Wyoming cratons of central North America is now possible. Little evidence exists of subducted slabs similar to modern oceanic lithosphere in these construction histories whereas underthrusting and wedging of proto-continental lithosphere is inferred from multiple dipping discontinuities. Archean continental building blocks may resemble the modern lithosphere of Ontong-Java-Hikurangi oceanic plateau. Radiometric dating of xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences. These ages can be correlated to surface rocks. The 3.6-2.6 Ga Rae, Slave and Wyoming cratons comprise smaller continental terranes that 'cratonized' during a granitic bloom at 2.61-2.55 ga. Cratonization probably represents the final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho atop depleted lithospheric mantle. Peak thermo-tectonic events at 1.86-1.7 Ga broadly metasomatized, mineralized and recrystallized mantle and lower crustal rocks, apparently making mantle peridotite more 'fertile' and conductive by introducing or concentrating sulfides or graphite throughout the lithosphere at 80-120 km depths. This metasomatism may have also weakened the lithosphere or made it more susceptible to tectonic or chemical erosion. The arrival of the subducted Shatsky Rise conjugate at the Wyoming craton at 65-75 Ma appears to have eroded and displaced the thus weakened base of the craton below 140-160 km. This replaced old refertilized continental mantle with new depleted oceanic mantle. Is this the same craton?

  5. Lateral heterogeneity and vertical stratification of cratonic lithospheric mantle

    NASA Astrophysics Data System (ADS)

    Artemieva, Irina; Cherepanova, Yulia; Lundvig, Kasper; Thybo, Hans; Vinnik, Lev; Xia, Bing

    2017-04-01

    We compare geophysical models for different cratons, with focus on structure and thermo-compositional heterogeneity of the lithospheric mantle. They include regional models of lithosphere density heterogeneity as constrained by free-board and satellite gravity data, thermal structure of the lithosphere based on surface heat flow data and supported by regional xenolith P-T arrays, and the non-thermal part of upper mantle seismic velocity heterogeneity based on joint analysis of thermal and seismic tomography data. Density structure of the cratonic lithosphere constrained independently by free-board and satellite gravity shows significant lateral variations, that are well correlated with crustal structure, surface tectonics, and regional xenolith data. In all cratons for which we have data the Archean - early Proterozoic cratonic nuclei has lower density than Proterozoic sutures and intracratonic basins. However, xenoliths never sample most depleted lithospheric mantle of the Archean nuclei. We analyze correlations between mantle density, lithosphere tectono-thermal age and the emplacement age of kimberlites. We also present correlations between the crustal structure and the density structure of the lithospheric mantle. Since the depth distribution of density anomalies cannot be constrained, we complement the analysis by seismic data. An analysis of temperature-corrected seismic velocity structure indicates strong vertical and lateral heterogeneity of the cratonic lithospheric mantle, with a pronounced stratification in many Precambrian terranes. We argue that a significant part of lateral and vertical heterogeneity of the cratonic lithosphere mantle can be explained by melt-metasomatism.

  6. Water in the Cratonic Mantle: Insights from FTIR Data on Lac De Gras Xenoliths (Slave Craton, Canada)

    NASA Technical Reports Server (NTRS)

    Peslier, Anne H.; Brandon, Alan D.; Schaffer, Lillian Aurora; O'Reilly, Suzanne Yvette; Griffin, William L.; Morris, Richard V.; Graff, Trevor G.; Agresti, David G.

    2014-01-01

    The mantle lithosphere beneath the cratonic part of continents is the deepest (> 200 km) and oldest (>2-3 Ga) on Earth, remaining a conundrum as to how these cratonic roots could have resisted delamination by asthenospheric convection over time. Water, or trace H incorporated in mineral defects, could be a key player in the evolution of continental lithosphere because it influences melting and rheology of the mantle. Mantle xenoliths from the Lac de Gras kimberlite in the Slave craton were analyzed by FTIR. The cratonic mantle beneath Lac de Gras is stratified with shallow (<145 km) oxidized ultradepleted peridotites and pyroxenites with evidence for carbonatitic metasomatism, underlain by reduced and less depleted peridotites metasomatized by kimberlite melts. Peridotites analyzed so far have H O contents in ppm weight of 7-100 in their olivines, 58 to 255 in their orthopyroxenes (opx), 11 to 84 in their garnet, and 139 in one clinopyroxene. A pyroxenite contains 58 ppm H2O in opx and 5 ppm H2O in its olivine and garnet. Olivine and garnet from the deep peridotites have a range of water contents extending to higher values than those from the shallow ones. The FTIR spectra of olivines from the shallow samples have more prominent Group II OH bands compared to the olivines from the deep samples, consistent with a more oxidized mantle environment. The range of olivine water content is similar to that observed in Kaapvaal craton peridotites at the same depths (129-184 km) but does not extend to as high values as those from Udachnaya (Siberian craton). The Slave, Kaapvaal and Siberian cratons will be compared in terms of water content distribution, controls and role in cratonic root longevity.

  7. Majorite Garnet and Lithosphere Evolution: Kaapvaal Craton

    NASA Astrophysics Data System (ADS)

    Griffin, W. L.; Tessalina, S.; O'Reilly, S. Y.

    2013-12-01

    The uppermost 50-70 km of the subcontinental lithospheric mantle (SCLM) beneath the Kaapvaal Craton (S. Africa) consists largely of highly-depleted chromite harzburgites. These rocks are understudied, mainly because of their uniformity and their lack of indicator minerals such as garnet and clinopyroxene (cpx). Kimberlite-borne xenoliths of these rocks contain rare volumes of cpx-spinel (modal 76/24) symplectite, with smooth grain boundaries; many studies have suggested that these might represent low-pressure breakdown products of garnet (majorite + olivine → cpx + spinel). Our reconstruction of a suite of these grains, using element mapping and EMP analysis of constituent minerals, gives a majoritic garnet with mean composition 21.8% CaO, 15.8% Cr2O3, 9.22% Al2O3, Si=3.118, mg#=0.93. The majorite contents suggest formation at depths of 250-280 km. Ni contents imply temperatures ≥1500 °C, but have large uncertainties related to the subtraction of olivine (ca 20%) during the reconstruction calculation. LAM-ICPMS analyses show strongly sinuous REE patterns with CN Dy/Lu <0.1 and Ce/Dy >100. Most analyses have negative Eu anomalies, consistent with chromite compositions that indicate strongly reducing conditions (ΔfO2(FMQ) = -4 to -5). Melt modeling suggests that the harzburgites are products of 30-40% melting of asthenospheric mantle at 250 km depth, leaving residues of ol+opx+chromite. The presence of the majorites and their overall LREE enrichment are ascribed to the introduction of carbonatitic metasomatic fluids, similar to those recorded by diamond-inclusions (subcalcic garnets), shortly after the depletion. We suggest that the melting, the metasomatism and the ultimate breakdown of the majorite track a process of mantle upwelling, with melt-extraction at depth providing the buoyancy that allowed the residual harzburgites to rise to shallow levels and stabilize the SCLM. Os-isotope analyses of sulfides associated with the majorites give TRD = 2.5-3.4 Ga

  8. SAO HMC photodetector/event timer engineering model test report

    SciTech Connect

    1994-10-05

    The test unit is a custom photodetector/event timer, PET, built for the Smithsonian Astrophysical Observatory, SAO, by Los Alamos which records elapsed time in 10 ps steps. The 1 Kg, 12 cm diameter PET unit uses 10 watts of electrical power and was tested to SAO`s specified flight conditions. The event timer has two inputs -- a reference clock oscillator input and a stop signal. Like a stop watch with split timing capability, the event timer records the instant a stop signal arrives. At that sample instant, the number of elapsed clock cycles are stored and the sample instant position between two reference clock edges is interpolated and stored. Then that stored data can be shifted serially to an external computer. The photodetector part of the PET responds to an optical input and provides the electrical output signal to the event timer specifying the sample instant. This test report discusses the event timer test results. Test equipment is shown for most of the operational tests. The relay rack contains test pursers and clocks. The environmental chamber controls temperature. The computer reads and records the serial data from the PET. Reported testing topics include: Pulse shapes to be used as test inputs, test results obtained using the electrical source`s input, optical test results which are the best simulation of specified operational conditions, heat sink operation in vacuum. Vibration tests performed to SAO`s specification.

  9. 112. Dennis Hill, Photographer January 1998 VIEW OF SAN FRANCISCO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    112. Dennis Hill, Photographer January 1998 VIEW OF SAN FRANCISCO VIADUCT (RIGHT), UPPER DECK OFF-RAMP (LEFT), AND LOWER DECK ON-RAMP FROM TRANSBAY TERMINAL BUS LOOP, FACING NORTHEAST. - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

  10. 10. Office of the Post Engineer, Presidio of San Francisco. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Office of the Post Engineer, Presidio of San Francisco. Location of Water Lines, Presidio of San Francisco. Sheet 30. November 1943. SHOWING EASTERN PORTION OF CRISSY FIELD AND AREA A. - Presidio of San Francisco, Storehouse & Administration, Crissy Field North cantonment, Allen Street, San Francisco, San Francisco County, CA

  11. 9. Office of the Post Engineer, Presidio of San Francisco. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Office of the Post Engineer, Presidio of San Francisco. Location of Water Lines, Presidio of San Francisco. Sheet 29. June 1944. SHOWING EASTERN PORTION OF CRISSY FIELD. - Presidio of San Francisco, Storehouse & Administration, Crissy Field North cantonment, Allen Street, San Francisco, San Francisco County, CA

  12. 36. Post Engineer Office, Presidio of San Francisco. Plot Plan, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. Post Engineer Office, Presidio of San Francisco. Plot Plan, Letterman Army Hospital, San Francisco, Calif. 1958. SHOWING LOCATION OF BUILDINGS 1006 AND 1049 IN LETTERMAN HOSPITAL COMPLEX IN 1958. - Presidio of San Francisco, Letterman General Hospital, Building No. 27, Letterman Hospital Complex, Edie Road, San Francisco, San Francisco County, CA

  13. ASTER Flyby of San Francisco

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Advanced Spaceborne Thermal Emission and Reflection radiometer, ASTER, is an international project: the instrument was supplied by Japan's Ministry of International Trade and Industry. A joint US/Japan science team developed algorithms for science data products, and is validating instrument performance. With its 14 spectral bands, extremely high spatial resolution, and 15 meter along-track stereo capability, ASTER is the zoom lens of the Terra satellite. The primary mission goals are to characterize the Earth's surface; and to monitor dynamic events and processes that influence habitability at human scales. ASTER's monitoring and mapping capabilities are illustrated by this series of images of the San Francisco area. The visible and near infrared image reveals suspended sediment in the bays, vegetation health, and details of the urban environment. Flying over San Francisco (3.2MB) (high-res (18.3MB)), we see the downtown, and shadows of the large buildings. Past the Golden Gate Bridge and Alcatraz Island, we cross San Pablo Bay and enter Suisun Bay. Turning south, we fly over the Berkeley and Oakland Hills. Large salt evaporation ponds come into view at the south end of San Francisco Bay. We turn northward, and approach San Francisco Airport. Rather than landing and ending our flight, we see this is as only the beginning of a 6 year mission to better understand the habitability of the world on which we live. For more information: ASTER images through Visible Earth ASTER Web Site Image courtesy of MITI, ERSDAC, JAROS, and the U.S./Japan ASTER Science Team

  14. Northern California near San Francisco

    NASA Image and Video Library

    1974-01-01

    SL4-138-3843 (1 Jan. 1974) --- A part of northern California centered near San Francisco Bay photographed at 3 p.m. Jan. 2, 1974, from the Skylab space station in Earth orbit. This near vertical view encompasses the coastline from Monterey Bay (right) to about 50 miles north of Point Reyes (left) and includes, from bottom to top, San Francisco Bay (center), Sacramento Valley (left center), San Joaquin Valley (right center), and the snow-covered Sierra Nevada. Afternoon shadows sharply delineate a valley which parallels San Francisco Bay, crosses Point Reyes, and lies between the Bay and the Pacific coastline. This valley marks the location of the San Andreas Fault, a major break in the Earth's crust. Forces acting on the crust are causing the land west (bottom) of the fault line to move north relative to land on the east side. The Skylab 4 astronauts photographed major fault zones in South America, New Zealand, Japan and Africa for use in the study of worldwide tectonic system. Agricultural areas in the Sacramento and San Joaquin Valleys are indicated by the tan areas which are easily discerned in contrast to the green-gray background. Photo credit: NASA

  15. Pampia: A large cratonic block missing in the Rodinia supercontinent

    NASA Astrophysics Data System (ADS)

    Ramos, Victor A.; Vujovich, Graciela; Martino, Roberto; Otamendi, Juan

    2010-09-01

    The large cratonic block of Pampia, at present in southern South America, is commonly missing in recent comprehensive reconstructions of Rodinia. This block was the conjugate margin of the Amazonia craton that corresponds to the W-NW-trending segment of the Sunsás orogen. This segment developed between Sucre in Bolivia and Corumbá in Brazil as a result of a Mesoproterozoic collision. The western margin of Pampia partially coincides with the southern part of the Arequipa-Antofalla terrane that was also amalgamated during the Mesoproterozoic. The Cuyania terrane, a Laurentian rifted continental block, was accreted to the southern sector of this margin of Pampia in middle Ordovician times. The northern sector of the eastern margin of Pampia is the lower plate of the Brasiliano belt developed along the Paranapanema craton during the early Cambrian collision associated with the closure of the Clymene Ocean. The southern sector of the eastern margin partially coincides with the southern extension of the Transbrasiliano lineament, which juxtaposed the Rio de La Plata Craton with the Pampia cratonic block. Along this eastern margin the Pampean-Paraguay orogen was formed during the late Brasiliano cycle in latest Proterozoic-Early Cambrian time. The southern margin was generated by the collision of Patagonia during late Paleozoic times. This cratonic block of Pampia, so defined, has western and northern sectors formed by Mesoproterozoic orogens, while the eastern sector is partially formed by juvenile Neoproterozoic crust, although older rocks cannot be ruled out. The Pampia cratonic block was the locus of several magmatic belts associated with important metamorphism during the Paleozoic and preserved in the central part at lower crustal levels.

  16. A Precambrian cratonic block in the west-central Chihuahua - The Sierra del Nido cratonic block

    SciTech Connect

    Goodell, P.C. . Dept. of Geological)

    1993-02-01

    Precambrian rocks in west-central Chihuahua have been recognized by Denison (1969) and Mauger et al. (1983), on the basis of radiometric dating. The rocks are rhyolite clasts, and an allucthonous block, respectively, however their source direction and vergence can be measured. They point back to and are on the edge of a large, uniform, negative Bouguer gravity anomaly, having values greater than 200 milligals. The isotopic geochemical character of several Tertiary felsic fields within this anomalous are has been determined, and initial strontium isotopic ratios are all greater than 0.7055. Outside the anomalous area these ratios are lower, and Basin and Range extension tectonism is more evident. It is proposed that a Precambrian cratonic block, the Sierra del Nido, is present in the crust in west-central Chihuahua. It is reasonable to propose that it was decreted from North America during a Precambrian extensional (1.1. By ) event, from somewhere along the Arizona Transition Zone-Texas Linament region. The Sierra del Nido Block is separated form the ATZ-TL by a region of disrupted craton and extended crust, the Basin and Range Province. Implications of the pressure of the Sierra del Nido Block on other regional tectonic events will be discussed.

  17. 77 FR 15260 - Safety Zone; San Francisco Fireworks Display, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-15

    ... safety zone for the San Francisco Giants Fireworks Display in the Captain of the Port, San Francisco area... position 37 46'39.9'' N, 122 23'06.78'' W (NAD83) for the San Francisco Giants Fireworks Display in 33 CFR...

  18. 76 FR 14051 - Notice of Inventory Completion: San Francisco State University, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-15

    ... inventory of human remains in the control of San Francisco State University, San Francisco, CA. The human... American human remains. The National Park Service is not responsible for the determinations in this notice. A detailed assessment of the human remains was made by San Francisco State University...

  19. Platinum-group element (PGE) geochemistry of Deccan orangeites, Bastar craton, central India: Implication for a non-terrestrial origin for iridium enrichment at the K-Pg boundary

    NASA Astrophysics Data System (ADS)

    Chalapathi Rao, N. V.; Lehmann, B.; Balaram, V.

    2014-04-01

    We report platinum group element (PGE) concentrations of twelve bulk-rock samples from the Behradih and Kodomali orangeite intrusions in the Mainpur field, Bastar craton, central India, which are emplaced synchronously with the Deccan flood basalts. Their palladium-group PGE (PPGE) (1.8-5.2 ppb Pt, 1.2-6.4 ppb Pd) contents are distinctly higher compared to their iridium-group PGE (IPGE) concentrations (0.8-2 ppb Os, 0.8-1.2 ppb Ir, 3.2-4.2 ppb Ru, and 0.2-0.8 ppb Rh). Their PGE contents as well as Pd/Ir ratios are either similar or even lower than those from the Mesoproterozoic and Cretaceous kimberlites and orangeites from the Kaapvaal craton (southern Africa), Cretaceous kimberlites from the Sao Fransisco craton (Brazil), Ordovician kimberlites from the North China craton and the Mesoproterozoic southern Indian kimberlites from the Eastern Dharwar craton. Anomalously elevated iridium (and other PGE) contents in sediments at the Cretaceous-Paleogene (K-Pg) boundary are commonly attributed either to a large bolide impact triggering the K-Pg mass extinction or to terrestrial causes such as volcanic eruptions (Deccan flood basalts) or even to mantle-plume derived lithospheric gaseous explosions (Verneshots). Lack of unusually high abundances of PGE in the Mainpur orangeties as well as in the co-eval Deccan flood basalts and associated alkaline rocks implies that the anomalous iridium enrichment reported at the K-Pg boundary sections was not sourced from the mantle and likely originated from an extraterrestrial source.

  20. 28. Photocopy of photograph (from San Francisco Chronicle Library, San ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. Photocopy of photograph (from San Francisco Chronicle Library, San Francisco, California, c. 1930 (?) EXTERIOR, DETAIL OF MISSION BELL IN FRONT OF CONVENTO, C. 1930 (?) - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  1. The Acasta Gneiss - a Hadean cratonic nucleus

    NASA Astrophysics Data System (ADS)

    Sprung, P.; Scherer, E. E.; Maltese, A.; Bast, R.; Bleeker, W.; Mezger, K.

    2016-12-01

    The known terrestrial rock record lacks undisputed, chemically intact Hadean crust. Direct evidence from this eon has been restricted to zircon grains within younger rocks [1]. The Acasta Gneiss Complex (AGC; NT, CA) has yielded zircon with Hadean domains [e.g., 2,3], but the time at which AGC rocks became closed chemical systems is unclear [4,5]. Determining this `time of last disturbance' (tld) would provide a minimum protolith age, and is crucial for using radiogenic isotope compositions of bulk rocks to trace crust-mantle evolution. Recent studies mostly focused on the `low-strain' eastern AGC [e.g., 6, 7], which records an evolving, early-mid Archean cratonic nucleus [7]. We also studied the `high-strain' banded gneiss in the western AGC, which hosts >4 Ga zircon domains [2,3], too. Our focusing lay on adjoining, lithologically distinct bands [8] of two distinct chemical groups: A) Mafic, chondrite-normalized LaN/YbN ≦20, slightly HFSE- depleted, and B) TTG-like, LaN/YbN up to 145, markedly HFSE-depleted. Six adjacent bands yield a well-defined 4 Ga Sm-Nd isochron with a ɛNd4Ga of +2 and ɛHf4Ga values from +1 to +6. Within-band Sm-Nd and Lu-Hf systematics imply younger mineral re-equilibration [9]. We interpret the 4 Ga Sm-Nd isochron to date the physical juxtaposition of bands in the gneiss unit and to define tld among bands for elements less mobile and diffusive than Sm and Nd. Contrasting Sm-Nd results from the same unit [10] likely are due to sampling at too fine a scale. Digestion of metamict pre-tld zircon likely caused the scatter in Lu-Hf. Both decay systems hint at the existence of a possibly local, strongly depleted Hadean mantle domain. The TTG-like bands are 0.4 Gyr older than similar rocks in the `low-strain' eastern AGC [7]. The AGC was thus an evolved cratonic nucleus already at 4 Ga, possibly with a depleted lithospheric keel. [1] Cavosie et al. (2004) Prec. Res. 135, 251-279 [2] Bowring & Williams (1999) CMP 134, 3-16 [3] Iizuka et al

  2. Smithsonian Astrophysical Observatory (SAO) star catalog (Sao staff 1966, edition ADC 1989): Documentation for the machine-readable version

    NASA Technical Reports Server (NTRS)

    Roman, Nancy G.; Warren, Wayne H., Jr.

    1989-01-01

    An updated, corrected, and extended machine readable version of the catalog is described. Published and unpublished errors discovered in the previous version were corrected, and multiple star and supplemental BD identifications were added to stars where more than one SAO entry has the same Durchmusterung number. Henry Draper Extension (HDE) numbers were added for stars found in both volumes of the extension. Data for duplicate SAO entries (those referring to the same star) were flagged. J2000 positions in usual units and in radians were added.

  3. Promoting the Earth Charter in Sao Paulo's Municipal Education System

    ERIC Educational Resources Information Center

    Inojosa, Rose Marie

    2010-01-01

    This article presents the process of widespread teacher training based on the Earth Charter in the municipal area of Sao Paulo, Brazil, South America. This effort diffused knowledge of the Earth Charter through 800 educators and by means of them, to one million children. This process was developed by the team from UMAPAZ--Open University of the…

  4. Constructing a Public Popular Education in Sao Paulo, Brazil.

    ERIC Educational Resources Information Center

    Wong, Pia Lindquist

    1995-01-01

    Examines school reform implemented by Paulo Freire and the Workers' Party in Sao Paulo during 1989-92. Focuses on various institutional mechanisms created to support teachers' efforts to learn the skills necessary for realization of reform objectives. Appendices list reform objectives and outline phases and activities in a teacher-directed…

  5. Automation in the Libraries of the City of Sao Paulo.

    ERIC Educational Resources Information Center

    McLean, D. D.

    1983-01-01

    Twenty selected Sao Paulo, Brazil, librarians who were interviewed indicated that, in their opinion, the development of library automation in this city is hampered by poor resources and cooperation, lack of professional and technical automation expertise, communication, and other psychological, organizational, and human related factors.…

  6. SAO During the Whipple Years: The Origins of Project Celescope

    NASA Astrophysics Data System (ADS)

    Devorkin, David

    2005-01-01

    In 1955, the moribund Astrophysical Observatory of the Smithsonian Institution closed its doors on the south lawn of the Smithsonian Castle. Vestiges of its 60-year old legacy of monitoring solar radiation were transferred to Cambridge under a new name, the Smithsonian Astrophysical Observatory, and became housed within the Harvard College Observatory complex under the direction of Fred Whipple. Whipple, restarting the SAO almost from scratch, worked within the Smithsonian's ancient tradition of maintaining a world-wide network of solar observation stations by morphing it into a similar network of satellite tracking facilities for the IGY, quickly and quietly phasing out the solar work. Under the SAO name, however, Whipple did much more, vastly expanding his interests in meteor research and hyperballistic studies, deftly orchestrated to parallel his tracking facility empire which in time included aeroballistic studies, atomic time standards, and other associated technological and scientific campaigns. He also made sure SAO played a prominent role in NASA's emerging `observatory class' series of scientific satellites and used it to create a theoretical astrophysics unit. It is this last activity that we will introduce here, showing how Project Celescope fitted into Whipple's plan for SAO, and how it contributed to make the combined Harvard-Smithsonian Center for Astrophysics the largest astronomical organization on the planet by the 1970s.

  7. Promoting the Earth Charter in Sao Paulo's Municipal Education System

    ERIC Educational Resources Information Center

    Inojosa, Rose Marie

    2010-01-01

    This article presents the process of widespread teacher training based on the Earth Charter in the municipal area of Sao Paulo, Brazil, South America. This effort diffused knowledge of the Earth Charter through 800 educators and by means of them, to one million children. This process was developed by the team from UMAPAZ--Open University of the…

  8. Prelimary Photoelectric Light Curve for DHK29=SAO 70629

    NASA Astrophysics Data System (ADS)

    Kaiser, Daniel H.; Gunn, Jerry B.; Lamb, Charles F.; Sullivan, Philip

    The newly discovered eclipsing binary star DHK 29 = SAO 70629 has been observed photoelectrically from October 1992 to October 1993. With the light curve coverage 75% complete, it is apparent that the initial 1.9-day period reported in IB VS 3815 is the half-period. Three times of primary minima have been determined. New light elements are given.

  9. Biological effects of air pollution in Sao Paulo and Cubatao

    SciTech Connect

    Boehm, G.M.S.; Saldiva, P.H.; Pasqualucci, C.A.; Massad, E.; Martins M de, E.; Zin, W.A.; Cardoso, W.V.; Criado, P.M.; Komatsuzaki, M.; Sakae, R.S. )

    1989-08-01

    Rats were used as biological indicators of air quality in two heavily polluted Brazilian towns: Sao Paulo and Cubatao. They were exposed for 6 months to ambient air in areas where the pollution was known to be severe. The following parameters were studied and compared to those of control animals: respiratory mechanics, mucociliary transport, morphometry of respiratory epithelium and distal air spaces, and general morphological alterations. The results showed lesions of the distal and upper airways in rats exposed in Cubatao, whereas the animals from Sao Paulo showed only alterations of the upper airways but of greater intensity than those observed in the Cubatao group. There are both qualitative and quantitative differences in the pollutants of these places: in Sao Paulo automobile exhaust gases dominate and in Cubatao the pollution is due mainly to particulates of industrial sources. The correlation of the pathological findings with the pollutants is discussed and it is concluded that biological indicators are useful to monitor air pollutions which reached dangerous levels in Sao Paulo and Cubatao.

  10. Constructing a Public Popular Education in Sao Paulo, Brazil.

    ERIC Educational Resources Information Center

    Wong, Pia Lindquist

    1995-01-01

    Examines school reform implemented by Paulo Freire and the Workers' Party in Sao Paulo during 1989-92. Focuses on various institutional mechanisms created to support teachers' efforts to learn the skills necessary for realization of reform objectives. Appendices list reform objectives and outline phases and activities in a teacher-directed…

  11. Automation in the Libraries of the City of Sao Paulo.

    ERIC Educational Resources Information Center

    McLean, D. D.

    1983-01-01

    Twenty selected Sao Paulo, Brazil, librarians who were interviewed indicated that, in their opinion, the development of library automation in this city is hampered by poor resources and cooperation, lack of professional and technical automation expertise, communication, and other psychological, organizational, and human related factors.…

  12. [Statistical considerations of isolated maxillofacial fractures in Sao Paulo].

    PubMed

    Crivello, O; Luz, J G; Lemos, J B; Rezende, J R

    1989-01-01

    Statistical analysis of 550 isolated maxillo-facial fractures is presented. Data obtained illustrated the important number of maxillo-facial fractures in Sao Paulo, the automobilistics accidents were responsible for most maxillo-facial trauma, the jaw and the malar were more predominant than the others structures and the conservative treatment was the most used one.

  13. The 3-dimensional construction of the Rae craton, central Canada

    NASA Astrophysics Data System (ADS)

    Snyder, David B.; Craven, James A.; Pilkington, Mark; Hillier, Michael J.

    2015-10-01

    Reconstruction of the 3-dimensional tectonic assembly of early continents, first as Archean cratons and then Proterozoic shields, remains poorly understood. In this paper, all readily available geophysical and geochemical data are assembled in a 3-D model with the most accurate bedrock geology in order to understand better the geometry of major structures within the Rae craton of central Canada. Analysis of geophysical observations of gravity and seismic wave speed variations revealed several lithospheric-scale discontinuities in physical properties. Where these discontinuities project upward to correlate with mapped upper crustal geological structures, the discontinuities can be interpreted as shear zones. Radiometric dating of xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences. These ages can also be correlated to surface rocks. The 3.6-2.6 Ga Rae craton comprises at least three smaller continental terranes, which "cratonized" during a granitic bloom. Cratonization probably represents final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho. The peak thermotectonic event at 1.86-1.7 Ga was associated with the Hudsonian orogeny that assembled several cratons and lesser continental blocks into the Canadian Shield using a number of southeast-dipping megathrusts. This orogeny metasomatized, mineralized, and recrystallized mantle and lower crustal rocks, apparently making them more conductive by introducing or concentrating sulfides or graphite. Little evidence exists of thin slabs similar to modern oceanic lithosphere in this Precambrian construction history whereas underthrusting and wedging of continental lithosphere is inferred from multiple dipping discontinuities.

  14. San Francisco floating STOLport study

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The operational, economic, environmental, social and engineering feasibility of utilizing deactivated maritime vessels as a waterfront quiet short takeoff and landing facility to be located near the central business district of San Francisco was investigated. Criteria were developed to evaluate each site, and minimum standards were established for each criterion. Predicted conditions at the two sites were compared to the requirements for each of the 11 criteria as a means of evaluating site performance. Criteria include land use, community structure, economic impact, access, visual character, noise, air pollution, natural environment, weather, air traffic, and terminal design.

  15. South San Francisco Bay, California

    USGS Publications Warehouse

    Dartnell, Peter; Gibbons, Helen

    2007-01-01

    View eastward. Elevations in mapped area color coded: purple (approx 15 m below sea level) to red-orange (approx 90 m above sea level). South San Francisco Bay is very shallow, with a mean water depth of 2.7 m (8.9 ft). Trapezoidal depression near San Mateo Bridge is where sediment has been extracted for use in cement production and as bay fill. Land from USGS digital orthophotographs (DOQs) overlaid on USGS digital elevation models (DEMs). Distance across bottom of image approx 11 km (7 mi); vertical exaggeration 1.5X.

  16. Archean crustal evolution of the northern North China Craton

    NASA Technical Reports Server (NTRS)

    Qian, Xianglin; Chen, Yaping; Liu, Jinzhong

    1988-01-01

    The Archean granultie facies rocks of the North China (Sino-Korean) Craton mostly occur inside the northern boundary forming a unique and spectacular granulite belt trending roughly E-W from eastern Hebei, North China in the east to Mt. Daqinchan, western Inner Mongolia in the west, ranging about 1,000 km long. Over the years in the middle portion of this Archean high-grade metamorphic belt a stratigraphic unconformity between the khondalite rock assemblage and the medium in composition granulite assemblage in Datong-Xinghe area is determined. The geological structural properties of the North China Craton are discussed.

  17. The Role of Water in the Stability of Cratonic Keels

    NASA Technical Reports Server (NTRS)

    Peslier, Anne H.; Woodland, Alan B.; Bell, David R.; Lazarov, Marina

    2011-01-01

    Cratons are typically underlain by large, deep, and old lithospheric keels (to greater than 200 km depth, greater than 2.5 Ga old) projecting into the asthenosphere (e.g., Jordan, 1978; Richardson et al., 1984). This has mystified Earth scientists as the dynamic and relatively hot asthenosphere should have eroded away these keels over time (e.g., Sleep, 2003; O'Neill et al., 2008; Karato, 2010). Three key factors have been invoked to explain cratonic root survival: 1) Low density makes the cratonic mantle buoyant (e.g., Poudjom Djomani et al., 2001). 2) Low temperatures (e.g., Pollack, 1986; Boyd, 1987), and 3) low water contents (e.g., Pollack, 1986), would make cratonic roots mechanically strong. Here we address the mechanism of the longevity of continental mantle lithosphere by focusing on the water parameter. Although nominally anhydrous , olivine, pyroxene and garnet can accommodate trace amounts of water in the form of H bonded to structural O in mineral defects (e.g., Bell and Rossman, 1992). Olivine softens by orders of magnitude if water (1-1000 ppm H2O) is added to its structure (e.g., Mackwell et al., 1985). Our recent work has placed constraints on the distribution of water measured in peridotite minerals in the cratonic root beneath the Kaapvaal in southern Africa (Peslier et al., 2010). At P greater than 5 GPa, the water contents of pyroxene remain relatively constant while those of olivine systematically decrease from 50 to less than 10 ppm H2O at 6.4 GPa. We hypothesized that at P greater than 6.4 GPa, i.e. at the bottom of the cratonic lithosphere, olivines are essentially dry (greater than 10 ppm H2O). As olivine likely controls the rheology of the mantle, we calculated that the dry olivines could be responsible for a contrast in viscosity between cratonic lithosphere and surrounding asthenosphere large enough to explain the resistance of cratonic root to asthenospheric delamination.

  18. Formation of cratonic lithosphere: An integrated thermal and petrological model

    NASA Astrophysics Data System (ADS)

    Herzberg, Claude; Rudnick, Roberta

    2012-09-01

    The formation of cratonic mantle peridotite of Archean age is examined within the time frame of Earth's thermal history, and how it was expressed by temporal variations in magma and residue petrology. Peridotite residues that occupy the lithospheric mantle are rare owing to the effects of melt-rock reaction, metasomatism, and refertilization. Where they are identified, they are very similar to the predicted harzburgite residues of primary magmas of the dominant basalts in greenstone belts, which formed in a non-arc setting (referred to here as "non-arc basalts"). The compositions of these basalts indicate high temperatures of formation that are well-described by the thermal history model of Korenaga. In this model, peridotite residues of extensive ambient mantle melting had the highest Mg-numbers, lowest FeO contents, and lowest densities at ~ 2.5-3.5 Ga. These results are in good agreement with Re-Os ages of kimberlite-hosted cratonic mantle xenoliths and enclosed sulfides, and provide support for the hypothesis of Jordan that low densities of cratonic mantle are a measure of their high preservation potential. Cratonization of the Earth reached its zenith at ~ 2.5-3.5 Ga when ambient mantle was hot and extensive melting produced oceanic crust 30-45 km thick. However, there is a mass imbalance exhibited by the craton-wide distribution of harzburgite residues and the paucity of their complementary magmas that had compositions like the non-arc basalts. We suggest that the problem of the missing basaltic oceanic crust can be resolved by its hydration, cooling and partial transformation to eclogite, which caused foundering of the entire lithosphere. Some of the oceanic crust partially melted during foundering to produce continental crust composed of tonalite-trondhjemite-granodiorite (TTG). The remaining lithosphere gravitationally separated into 1) residual eclogite that continued its descent, and 2) buoyant harzburgite diapirs that rose to underplate cratonic nuclei

  19. Archean crustal evolution of the northern North China Craton

    NASA Technical Reports Server (NTRS)

    Qian, Xianglin; Chen, Yaping; Liu, Jinzhong

    1988-01-01

    The Archean granultie facies rocks of the North China (Sino-Korean) Craton mostly occur inside the northern boundary forming a unique and spectacular granulite belt trending roughly E-W from eastern Hebei, North China in the east to Mt. Daqinchan, western Inner Mongolia in the west, ranging about 1,000 km long. Over the years in the middle portion of this Archean high-grade metamorphic belt a stratigraphic unconformity between the khondalite rock assemblage and the medium in composition granulite assemblage in Datong-Xinghe area is determined. The geological structural properties of the North China Craton are discussed.

  20. Jack London and the San Francisco earthquake

    USGS Publications Warehouse

    Sachs, J.S.

    1982-01-01

    After it was over, it seemed to many, and especially to eyewitnesses like Jack London, that the earthquake and fire had devastated San Francisco. However people were confident that, like the phoeniz, San Francisco would rise from the ashes and regain her palce as the "Imperial City of the West." 

  1. Trouble Brewing in San Francisco. Policy Brief

    ERIC Educational Resources Information Center

    Buck, Stuart

    2010-01-01

    The city of San Francisco will face enormous budgetary pressures from the growing deficits in public pensions, both at a state and local level. In this policy brief, the author estimates that San Francisco faces an aggregate $22.4 billion liability for pensions and retiree health benefits that are underfunded--including $14.1 billion for the city…

  2. The story of a craton from heart to margins: illuminating cratonic lithosphere with Rayleigh wave phase velocities in Eastern Canada

    NASA Astrophysics Data System (ADS)

    Petrescu, L.; Darbyshire, F. A.; Gilligan, A.; Bastow, I. D.; Totten, E. J.

    2015-12-01

    Cratons are Precambrian continental nuclei that are geologically distinct from modern continental regions and are typically underlain by seismically fast lithospheric roots (keels) to at least 200 km depth. Both plate and non-plate tectonic origin theories such as stacking of subducted slabs or multiple mantle plume underplating have been proposed to explain keel growth.Eastern Canada is an ideal continental region to investigate cratonization processes and the onset of plate tectonics. It comprises part of the largest Archean craton in the world, the Superior Province, flanked by a ~1.1 Ga Himalayan-scale orogenic belt, the Grenville Province, and the 500-300 Ma old Appalachian orogenic province, following the same general SW-NE axial trend. The region is also cross-cut by the Great Meteor Hotspot track, providing an excellent opportunity to study the interaction of hotspot tectonism with progressively younger lithospheric domains.We investigate the lithospheric structure of Precambrian Eastern Canada using teleseismic earthquake data recorded at permanent and temporary networks. We measure interstation dispersion curves of Rayleigh wave phase velocities between ~15 and 220 s, and compare the results to standard continental and cratonic reference models. We combine the dispersion curves via a tomographic inversion which solves for isotropic phase velocity heterogeneity and azimuthal anisotropy across the region at a range of periods. The phase velocity maps indicate variations in lithospheric properties from the heart of the Superior craton to the SE Canadian coast.The new regional-scale models will help to understand the processes that generated, stabilized and reworked the cratonic roots through their billion-year tectonic history. We investigate how surface tectonic boundaries relate to deeper lithospheric structural changes, and consider the effects of the multiple Wilson cycles that affected Laurentia.

  3. Physico-chemical constraints on cratonic lithosphere discontinuities

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Rondenay, Stéphane; Huismans, Ritske

    2014-05-01

    The origins of the mid-lithospheric discontinuity (MLD) and lithosphere-asthenosphere boundary (LAB) have received much attention over the recent years. Peculiarities of cratonic lithosphere construction - compositional and rheological stratification due to thickening in collisional settings or by plume subcretion, multiple metasomatic overprints due to longevity - offer a variety of possibilities for the generation of discontinuities. Interconnected small degrees of conductive partial melt (carbonate-rich melts, such as carbonatites and kimberlites, or highly alkaline melts) at the cratonic LAB, which produce seismic discontinuities, may be generated in the presence of volatiles. These depress the peridotite solidus sufficiently to intersect the mantle adiabat at depths near the cratonic LAB at ~160-220 km, i.e. above the depth of metal saturation where carbonatite becomes unstable. The absence of agreement between the different seismic and magnetotelluric estimates for the depth of the LAB beneath Kaapvaal may be due to impingement of a plume, leading to a pervasively, but heterogeneously metasomatised ('asthenospherised') hot and deep root. Such a root and hot sublithosphere may yield conflicting seismic-thermal-geochemical depths for the LAB. The question arises whether the chemical boundary layer should be defined as above or below the asthenospherised part of the SCLM, which has preserved isotopic, compositional (non-primitive olivine forsterite content) and physical evidence (e.g. from teleseismic tomography and receiver functions) for a cratonic heritage and which therefore is still distinguishable from the asthenospheric mantle. If cratonic lithosphere overlies anomalously hot mantle for extended periods of time, the LAB may be significantly thinned, aided by penetration of relatively high-degree Fe-rich partial melts, as has occurred beneath the Tanzanian craton. Xenoliths from the deep Slave craton show little evidence for 'asthenospherisation'. Its root

  4. Water in the Cratonic Mantle: Insights from FTIR Data on Lac de Gras Xenoliths (Slave Craton, Canada)

    NASA Astrophysics Data System (ADS)

    Peslier, A. H.; Brandon, A. D.; Schaffer, L. A.; O'Reilly, S. Y.; Griffin, W. L.; Morris, R. V.; Graff, T. G.; Agresti, D. G.

    2014-12-01

    The mantle lithosphere beneath the cratonic part of continents is the deepest (> 200 km) and oldest (>2-3 Ga) on Earth, remaining a conundrum as to how these cratonic roots could have resisted delamination by asthenospheric convection over time. Water, or trace H incorporated in mineral defects, could be a key player in the evolution of continental lithosphere because it influences melting and rheology of the mantle [e.g., 1]. Mantle xenoliths from the Lac de Gras kimberlite in the Slave craton [2] were analyzed by FTIR. The cratonic mantle beneath Lac de Gras is stratified with shallow (<145 km) oxidized ultradepleted peridotites and pyroxenites with evidence for carbonatitic metasomatism, underlain by reduced and less depleted peridotites metasomatized by kimberlite melts [3,4]. Peridotites analyzed so far have H2O contents in ppm weight of 7-100 in their olivines, 58 to 255 in their orthopyroxenes (opx), 11 to 84 in their garnet, and 139 in one clinopyroxene. A pyroxenite contains 58 ppm H2O in opx and 5 ppm H2O in its olivine and garnet. Olivine and garnet from the deep peridotites have a range of water contents extending to higher values than those from the shallow ones. The FTIR spectra of olivines from the shallow samples have more prominent Group II OH bands compared to the olivines from the deep samples, consistent with a more oxidized mantle environment [5]. The range of olivine water content is similar to that observed in Kaapvaal craton peridotites at the same depths (129-184 km [1]) but does not extend to as high values as those from Udachnaya (Siberian craton [6]). The Slave, Kaapvaal and Siberian cratons will be compared in terms of water content distribution, controls and role in cratonic root longevity. [1] Peslier et al. 2010 Nature 467, 78-81. [2] Aulbach et al. 2007 CMP 154, 409-427. [3] Creighton et al. 2009 CMP 157, 491-504. [4] Aulbach et al. 2013 CG 352, 153-169. [5] Bai & Kohlstedt 1993 PCM 19, 460-471. [6] Doucet et al. 2014 GCA 137, 159-187.

  5. Establishment and characterization of a new highly metastatic human osteosarcoma cell line derived from Saos2

    PubMed Central

    Du, Lin; Fan, Qiming; Tu, Bing; Yan, Wei; Tang, Tingting

    2014-01-01

    Osteosarcoma is the most common primary malignancy of bone in adolescents and young adults. There is a shortage of tumorigenic and highly metastatic human osteosarcoma cell lines that can be used for metastasis study. Here we establish and characterize a highly metastatic human osteosarcoma cell line that is derived from Saos2 cell line based on bioluminescence. The occasional pulmonary metastatic cells developed from Saos2 were isolated, harvested, characterized and named Saos2-l. The parental Saos2 and Saos2-l cells were further characterized both in vitro and in vivo. Results showed that Saos2-l cells demonstrated increased cell adhesion, migration and invasion compared to the parental Saos2 cells. Conversely, Saos2-l cells grew at a slightly slower rate than that of the parental cells. When injected into nude mice, Saos2-l cells had a greater increase in developing pulmonary metastases compared to the parental Saos2 cells. Further transcriptional profiling analysis revealed that some gene expression were up-regulated or down-regulated in the highly metastatic Saos2-l cells, indicating possible influencing factors of metastasis. Thus, we have established and characterized a highly metastatic human osteosarcoma cell line that should serve as a valuable tool for future investigations on the pathogenesis, metastasis and potential treatments of human osteosarcoma. PMID:25031706

  6. Recycling lower continental crust in the North China craton.

    PubMed

    Gao, Shan; Rudnick, Roberta L; Yuan, Hong-Ling; Liu, Xiao-Ming; Liu, Yong-Sheng; Xu, Wen-Liang; Ling, Wen-Li; Ayers, John; Wang, Xuan-Che; Wang, Qing-Hai

    2004-12-16

    Foundering of mafic lower continental crust into underlying convecting mantle has been proposed as one means to explain the unusually evolved chemical composition of Earth's continental crust, yet direct evidence of this process has been scarce. Here we report that Late Jurassic high-magnesium andesites, dacites and adakites (siliceous lavas with high strontium and low heavy-rare-earth element and yttrium contents) from the North China craton have chemical and petrographic features consistent with their origin as partial melts of eclogite that subsequently interacted with mantle peridotite. Similar features observed in adakites and some Archaean sodium-rich granitoids of the tonalite-trondhjemite-granodiorite series have been interpreted to result from interaction of slab melts with the mantle wedge. Unlike their arc-related counterparts, however, the Chinese magmas carry inherited Archaean zircons and have neodymium and strontium isotopic compositions overlapping those of eclogite xenoliths derived from the lower crust of the North China craton. Such features cannot be produced by crustal assimilation of slab melts, given the high Mg#, nickel and chromium contents of the lavas. We infer that the Chinese lavas derive from ancient mafic lower crust that foundered into the convecting mantle and subsequently melted and interacted with peridotite. We suggest that lower crustal foundering occurred within the North China craton during the Late Jurassic, and thus provides constraints on the timing of lithosphere removal beneath the North China craton.

  7. 42. Post Engineer Office, Presidio of San Francisco, Letterman Army ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. Post Engineer Office, Presidio of San Francisco, Letterman Army Hospital, X-Ray Department and Second Floor Plan, X-Ray Department Plan, Building 1006. no date. BUILDING 1006. - Presidio of San Francisco, Letterman General Hospital, Building No. 27, Letterman Hospital Complex, Edie Road, San Francisco, San Francisco County, CA

  8. 21. Post Engineer Office, Presidio of San Francisco, Letterman Army ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Post Engineer Office, Presidio of San Francisco, Letterman Army Hospital. EKG Cardiology Clinic, Building 1049. December 1955. BUILDING 1049. - Presidio of San Francisco, Letterman General Hospital, Building No. 12, Letterman Hospital Complex, Edie Road, San Francisco, San Francisco County, CA

  9. 22. Post Engineer Office, Presidio of San Francisco, Building # ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Post Engineer Office, Presidio of San Francisco, Building # 1049 Letterman General Hospital. Alterations to EKG Cardiology Clinic. November 1963. BUILDING 1049. - Presidio of San Francisco, Letterman General Hospital, Building No. 12, Letterman Hospital Complex, Edie Road, San Francisco, San Francisco County, CA

  10. Presidio of San Francisco. Sheet 27. June 1945. SHOWING EASTERN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Presidio of San Francisco. Sheet 27. June 1945. SHOWING EASTERN PORTION OF AREA B, BUILDINGS 901-919 AND WESTERN PORTION OF CRISSY FIELD - Presidio of San Francisco, Enlisted Men's Barracks Type, West end of Crissy Field, between Pearce & Maudlin Streets, San Francisco, San Francisco County, CA

  11. Presidio of San Francisco. Sheet 26. March 1943. SHOWING AREA ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Presidio of San Francisco. Sheet 26. March 1943. SHOWING AREA B, BUILDINGS 901-919; PART OF BUILDINGS 949 AND 950 ARE SHOWN IN UPPER LIFT CORNER OF DRAWING - Presidio of San Francisco, Enlisted Men's Barracks Type, West end of Crissy Field, between Pearce & Maudlin Streets, San Francisco, San Francisco County, CA

  12. 41. Post Engineer Office, Presidio of San Francisco, Letterman Army ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Post Engineer Office, Presidio of San Francisco, Letterman Army Hospital, First Floor Plan, Main Laboratory Section and Plan, Building 1006. no date BUILDING 1006. - Presidio of San Francisco, Letterman General Hospital, Building No. 27, Letterman Hospital Complex, Edie Road, San Francisco, San Francisco County, CA

  13. 34. Fort Winfield Scott and Presidio of San Francisco. August ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. Fort Winfield Scott and Presidio of San Francisco. August 1918. SHOWING THE LETTERMAN HOSPITAL COMPLEX, FOLLOWING CONSTRUCTION OF BUILDING 1006 AND 1049, IN CONTEXT WITH ENTIRE PRESIDIO IN 1918. - Presidio of San Francisco, Letterman General Hospital, Building No. 27, Letterman Hospital Complex, Edie Road, San Francisco, San Francisco County, CA

  14. Temperature-dependent transient creep and dynamics of cratonic lithosphere

    NASA Astrophysics Data System (ADS)

    Birger, Boris I.

    2013-11-01

    Large-scale mantle convection forms the upper boundary layer (lithosphere) where the vertical temperature drop is about 1300 K. Theoretical rheology and laboratory experiments with rock samples show that transient creep occurs while creep strains are sufficiently small. The transient creep is described by the temperature-dependent Andrade rheological model. Since plate tectonics allows only small deformations in lithospheric plates, creep of the lithosphere plates is transient whereas steady-state creep, described by non-Newtonian power-law rheological model, takes place in the underlying mantle. The solution of stability problem shows that the lithosphere is stable but small-scale convective oscillations are attenuated very weakly in regions of thickened lithosphere beneath continental cratons (subcratonic roots) where the thickness of the lithosphere is about 200 km. These oscillations create small-scale convective cells (the horizontal dimensions of the cells are of the order of the subcratonic lithosphere thickness). Direction of motion within the cells periodically changes (the period of convective oscillations is of the order of 3 × 108 yr). In this study, the oscillations of cratonic lithosphere caused by initial relief perturbation are considered. This relief perturbation is assumed to be created by overthrusting in orogenic belts surrounding cratons. The perturbation of the Earth's surface relief leads to a fast isothermal process of isostatic recovery. In the presence of vertical temperature gradient, vertical displacements, associated with the recovery process in the lithosphere interior, instantly produce the initial temperature perturbations exciting thermoconvective oscillations in the cratonic lithosphere. These small-amplitude convective oscillations cause oscillatory crustal movements which form sedimentary basins on cratons.

  15. Space Radar Image of San Francisco, California

    NASA Image and Video Library

    1999-04-15

    This image of San Francisco, California shows how the radar distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. Downtown San Francisco is at the center and the city of Oakland is at the right across the San Francisco Bay. Some city areas, such as the South of Market, called the SOMA district in San Francisco, appear bright red due to the alignment of streets and buildings to the incoming radar beam. Various bridges in the area are also visible including the Golden Gate Bridge (left center) at the opening of San Francisco Bay, the Bay Bridge (right center) connecting San Francisco and Oakland, and the San Mateo Bridge (bottom center). All the dark areas on the image are relatively smooth water: the Pacific Ocean to the left, San Francisco Bay in the center, and various reservoirs. Two major faults bounding the San Francisco-Oakland urban areas are visible on this image. The San Andreas fault, on the San Francisco peninsula, is seen in the lower left of the image. The fault trace is the straight feature filled with linear reservoirs which appear dark. The Hayward fault is the straight feature on the right side of the image between the urban areas and the hillier terrain to the east. The image is about 42 kilometers by 58 kilometers (26 miles by 36 miles) with north toward the upper right. This area is centered at 37.83 degrees north latitude, 122.38 degrees east longitude. http://photojournal.jpl.nasa.gov/catalog/PIA01791

  16. Space Radar Image of San Francisco, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This image of San Francisco, California shows how the radar distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. Downtown San Francisco is at the center and the city of Oakland is at the right across the San Francisco Bay. Some city areas, such as the South of Market, called the SOMA district in San Francisco, appear bright red due to the alignment of streets and buildings to the incoming radar beam. Various bridges in the area are also visible including the Golden Gate Bridge (left center) at the opening of San Francisco Bay, the Bay Bridge (right center) connecting San Francisco and Oakland, and the San Mateo Bridge (bottom center). All the dark areas on the image are relatively smooth water: the Pacific Ocean to the left, San Francisco Bay in the center, and various reservoirs. Two major faults bounding the San Francisco-Oakland urban areas are visible on this image. The San Andreas fault, on the San Francisco peninsula, is seen in the lower left of the image. The fault trace is the straight feature filled with linear reservoirs which appear dark. The Hayward fault is the straight feature on the right side of the image between the urban areas and the hillier terrain to the east. The image is about 42 kilometers by 58 kilometers (26 miles by 36 miles) with north toward the upper right. This area is centered at 37.83 degrees north latitude, 122.38 degrees east longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on October 3, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth.

  17. Lithospheric thinning in the Eastern Indian Craton: Evidence for lithospheric delamination below the Archean Singhbhum Craton?

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik

    2017-02-01

    We herein present shear velocity structure extending down to 300 km depth below the Archean Singhbhum-Odisha Craton (SOC) and Proterozoic Chotanagpur granitic-gneissic terrain (CGGT), which has been obtained through the inversion modeling of P-receiver functions. We use three-component broadband recordings of 200 teleseismic earthquakes (30° ≤ ∆ ≤ 90°) from a 15 station seismic network that has been operational in the Eastern Indian shield since February 2013. We obtain the thinnest crust of 35 km overlying a thin lithosphere of 78 km, below the region near south Singhbhum shear zone, which could be attributed to the 1.6 Ga plume activity associated with Dalma volcanic. However, the thickest crust of 47 km overlying a thin lithosphere of 81 km is noticed below the region near the Singhbhum granite of 3.6 Ga. This thinning of lithosphere could be attributed to the delamination of lithospheric root due to the Himalayan orogeny with a shortening rate of 2 cm/year. This delamination model in SOC gets further support from the densification of the lower crust, which could result from repeated episodes of basaltic underplating associated with episodes related to Dalma ( 1.6 Ga) and Rajmahal ( 117 Ma) volcanisms. This led to relatively more mafic, heterogeneous and deformed crustal structure in SOC as well as EGMB (with an average crustal Vs of 4.0 km/s) in comparison to that in CGGT (with an average crustal Vs of 3.9 km/s), as seen through our modeling results. The thickest lithosphere of 100 km is observed in the southwestern SOC as well as northeastern CGGT. We also notice that a sharp and flat Moho in CGGT, which could be attributed to thermal reactivation and large volume melting of the mafic cratonic crust during the late Archean subduction process and associated volcanism episodes. This model gets further support from the estimated 169 km thick lower Vs zone in the upper mantle below CGGT. Our modeling results also support a northward subduction of Archean

  18. Flat Slab Subduction, Trench Suction, and Craton Destruction: Comparison of the North China, Wyoming, and Brazilian Cratons

    NASA Astrophysics Data System (ADS)

    Kusky, Timothy; Windley, Brian; Wang, Lu; Wang, Zhensheng; Li, Xiaoyong; Zhu, Peimin

    2015-04-01

    We define and test a unifying plate tectonic driving mechanism that explains the characteristics of the destruction of cratonic lithospheric roots. We document and model the relationships between flat slab subduction, trench suction, and craton destruction, using examples from the North China and Wyoming cratons, each of which locally lost approximately 100 km of their lithospheric roots in the Cretaceous and which show spatio-temporal relationships with episodes of flat slab subduction in the mantle transition zone associated with deep mantle hydration, coupled with slab rollback and concomitant influx of fertile mantle material to accommodate the space created by slab rollback. A similar process has more recently operated along the western side of the Brazilian craton where it is thrust beneath the thickened crust of the Andes in an area of trench rollback. The importance of the mutual interaction between these processes for destruction of cratonic roots may be greater than currently perceived. Together with the other processes of subduction erosion and arc subduction, larger amounts of continental lithosphere may have been subducted or otherwise returned to the sub-lithospheric mantle than previously appreciated. When oceanic lithosphere subducts, it hydrates the upper mantle beneath an arc from well-known dehydration reactions. However, some hydrous phases (e.g., Phase A, Phase E, and -γt and β-phase olivine) are stable to much greater depths and dehydrate even when a slab is in the mantle transition zone. It is estimated that 40% of the water subducted in hydrated oceanic crust, mantle, sediments, and subducted continental material reaches the mantle transition zone between 410 and 660 km. For instance lawsonite may contain up to 11% water, and is stable up to 11 GPa or about 300 km and serpentinites can contain up to 13% water and are stable up to 7 GPa, and after conversion to denser hydrous phases such as β-phase olivine they can be stable up to 50 GPa

  19. 2. SAN FRANCISCO STREET PROFILES: Photocopy of engraving, c. 1880, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SAN FRANCISCO STREET PROFILES: Photocopy of engraving, c. 1880, showing street profiles of two San Francisco cable railroads. Figure 10 illustrates the mainline of the Sutter Street Railroad on Sutter Street, while Figure 11 shows the route of the Presidio & Ferries Railroad along Union Street. Note the lack of significant grades along the Sutter Street route. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

  20. 1. SAN FRANCISCO STREET PROFILES: Photocopy of engraving, c. 1880, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SAN FRANCISCO STREET PROFILES: Photocopy of engraving, c. 1880, showing street profiles of three San Francisco cable lines. Figure 7, at bottom of engraving, is the profile of Hallidie's Clay Street Hill Railroad. Figures 8 and 9 show the grades for the California Street Cable Railroad and the Geary Street Park & Ocean Railroad respectively. Note the lack of significant grades along Geary Street. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

  1. On the Origin of Cratonic Sag Basins: Did They Sag?

    NASA Astrophysics Data System (ADS)

    Morgan, Jason P.

    2015-04-01

    Cratonic sag basins are regions of long-lived, extremely slow (~20-30 m/Myr) shallow water and terrestrial sediment accumulation that have no striking signs of tectonic activity (cf. Allen and Armitage, 2012). In their evolution, hundreds of Myr-long periods of slow sediment accumulation are separated by unconformities. The mechanisms for their formation resist geodynamic characterization by other common hypotheses for basin subsidence because of their extremely slow subsidence and lack of evident tectonic activity. I propose their dynamics are better understood within the geodynamic context of continental cratons that ride over a ~250km-deep sub-asthenospheric mantle with lateral temperature variations between a few wide and persistent 1000s-km broad ~1400C 'superplume' upwelling mantle structures (e.g. currently beneath S. African Atlantic and French Polynesia) and prevalent surrounding ~1150C average temperature sub-asthenospheric mantle. When continents pass over typical mantle plumes, buoyant plume material tends to drain beneath the continent along junctions between cratons where the lithosphere is relatively thin, keeping the lithosphere over regions where plume material drains hotter than the average temperature of ~250km-deep mantle. (e.g., the Cameroon Line.) Regions where melting of plume material occurs during decompression associated with either plume ascent or lateral drainage beneath continents are associated with the addition of a buoyant rind of more depleted mantle to the continent. In addition, regions where plume material can pond in a relatively thin sub-lithospheric 'anti-basin' beneath a continent, or that stay stationary for long times over super plumes will heat to a lithospheric basal temperature of ~1400C instead of ~1150C, with ~700m of associated uplift. (e.g., Southern Africa). In this scenario (cf. Yamamoto, Morgan, and Morgan in "Plumes, Plates, and Paradigms"), it is the relative plume-passage-induced uplift of arches between

  2. Suicide Among Chinese in San Francisco

    ERIC Educational Resources Information Center

    Bourne, Peter G.

    1973-01-01

    Reports on a study which investigated suicide among Chinese in San Francisco, its relationship to age and sex distribution, place of birth, marital status, occupation, and methods and causes of suicide. (SF)

  3. Secrets Shared: A Conversation with Francisco Jimemez.

    ERIC Educational Resources Information Center

    Barrera, Rosalinda B.

    2003-01-01

    Presents an interview with Francisco Jimenez. Notes that he recently received the Tomas Rivera Mexican American Book Award for his authorship of "Breaking Through." Discusses his works and new ideas for future writing. (SG)

  4. A Community Stormwater Investigation, San Francisco, CA

    NASA Astrophysics Data System (ADS)

    Chio, J.; Garcia, E.; Hernandez, M.; Devine, M.; Isip, N.; Jiang, J.; Li, A.; Li, D.; Lopez, J.; Mark, J.; McGuire, S.; Navarro, K.; Negrete, R.; Orellana, S.; Yun, C.; Bissell, M.; Neiss, J.

    2008-12-01

    The San Francisco Bay watershed covers 40% of the State of California. Nonpoint source pollutants from cars, lawns, houses, parks and people residing within the watershed contribute contamination into San Francisco Bay. To measure the contribution from our neighborhoods we collected runoff from storm-drains at 10 different sites around San Francisco and tested them for heavy metals, Total Organic Carbons (TOC), and Methylene Blue Active Substances (MBAS) during a six-month period. Each sample site location is situated within one block of each participant's home. The goal of this study was to determine the contaminants contributed as nonpoint source pollution into San Francisco Bay. Our results show that a variety of contaminants are entering the Bay's ecosystem via sources in our residential settings. While this contribution may be thought of as unsubstantial, our results show that our neighborhoods are significant sources of watershed pollution.

  5. San Francisco and Bay Area, CA, USA

    NASA Image and Video Library

    1991-05-06

    STS039-89-053 (28 April-6 May 1991) --- A 70mm, infrared frame of the city of San Francisco, taken on a clear day. The gray areas represent urban regions, and the red areas are vegetated. Within the city of San Francisco, parks like Golden Gate park and the Presidio at the base of the Golden Gate Bridge easily stand out from the well-developed parts of the city. Major thoroughfares and bridges (Golden Gate and Bay Bridges) are seen as are other landmarks such as Candlestick Park and Alcatraz. The trace of the San Andreas faults show as a straight valley running northerly along the San Francisco peninsula. Good detail is visible in the turbid waters of San Francisco Bay.

  6. Secrets Shared: A Conversation with Francisco Jimemez.

    ERIC Educational Resources Information Center

    Barrera, Rosalinda B.

    2003-01-01

    Presents an interview with Francisco Jimenez. Notes that he recently received the Tomas Rivera Mexican American Book Award for his authorship of "Breaking Through." Discusses his works and new ideas for future writing. (SG)

  7. Paleomagnetism of the Wyoming Craton: A Pre-Laurentian Puzzle

    NASA Astrophysics Data System (ADS)

    Kilian, T.; Chamberlain, K.; Mitchell, R. N.; Evans, D. A.; Bleeker, W.; Lecheminant, A. N.

    2010-12-01

    The Archean Wyoming craton is mostly buried beneath Phanerozoic sediments in the Rocky Mountains of the west central United States. Exposures of the craton are entirely in thrust-bounded Laramide uplifts and contain numerous swarms of Neoarchean-Proterozoic mafic dikes. U-Pb ages from these dikes include ~2685 Ma from a dike in the Owl Creek Mountains (Frost et al., 2006) as well as another in the Bald Mountain region of the Bighorn Mountains (this study), ~2170 Ma from the Wind River Mountain quartz diorite (Harlan et al., 2003), ~2110 Ma from a dike in the Granite Mountains (Bowers and Chamberlain, 2006), ~2010 Ma from a Kennedy dike in the Laramie Range (Cox et al., 2000), and ~780 Ma for dikes in the Beartooth and Teton Mountains (Harlan et al., 1997). These possible age ranges of magmatic events will allow a detailed comparison with other cratons, especially Superior and Slave. Prior to the assembly of Laurentia, Wyoming may have been connected with Slave in supercraton Sclavia (Bleeker, 2003; Frost et al., 2007), or alternatively, Wyoming may have been attached to the present southern margin of Superior in the supercraton Superia, as judged by similarities of the thrice-glaciated Huronian and Snowy Pass sedimentary successions (Roscoe and Card, 1993). Paleomagnetic results will be presented from over 150 dikes in the Wyoming craton. All dikes were from the basement uplifts of the Beartooth Mountains, Bighorn Mountains, Owl Creek Mountains, Granite Mountains, Ferris Mountains and Laramie Range. Dikes range in widths from 1 to >100 meters, and trends vary across all orientations. Stable remanence is observed in majority of sites with at least 8 different directions from the various uplifts. Structural corrections are applied when necessary to restore shallowly dipping Cambrian strata to horizontal. The paleomagnetic study is being integrated with precise U-Pb geochronology of dikes that bear stable remanence directions. Results will eventually allow a

  8. Gila San Francisco Decision Support Tool - 2010

    SciTech Connect

    Sun, Amy Cha-Tien; Tidwell, Vincent C.; Klisa, Geoff; Poplionski, Will

    2014-12-01

    The Gila-San Francisco Decision Support Tool analyzes the water demand and supply for the Gila San Francisco region spanning four counties in southwestern New Mexico (Catron, Hidalgo, Luna and Grant). Catalyzed by the 2004 Arizona Water Settlement Act and prompted by a keen awareness for the unique ecology in the region, the model was developed by Sandia with a collaborative modeling team from federal, state, local, and public stakeholders

  9. The Fazenda Largo off-craton kimberlites of Piauí State, Brazil

    NASA Astrophysics Data System (ADS)

    Kaminsky, Felix V.; Sablukov, Sergei M.; Sablukova, Ludmila I.; Zakharchenko, Olga D.

    2009-10-01

    In the late 1990s, the Fazenda Largo kimberlite cluster was discovered in the Piauí State of Brazil. As with earlier known kimberlites in this area - Redondão, Santa Filomena-Bom Jesus (Gilbues) and Picos - this cluster is located within the Palaeozoic Parnaiba Sedimentary Basin that separates the São Francisco and the Amazonian Precambrian cratons. Locations of kimberlites are controlled by the 'Transbrasiliano Lineament'. The Fazenda Largo kimberlites are intensely weathered, almost completely altered rocks with a fine-grained clastic structure, and contain variable amounts of terrigene admixture (quartz sand). These rocks represent near-surface volcano-sedimentary deposits of the crater parts of kimberlite pipes. By petrographic, mineralogical and chemical features, the Fazenda Largo kimberlites are similar to average kimberlite. The composition of the deep-seated material in the Fazenda Largo kimberlites is quite diverse: among mantle microxenoliths are amphibolitised pyrope peridotites, garnetised spinel peridotites, ilmenite peridotites, chromian spinel + chromian diopside + pyrope intergrowths, and large xenoliths of pyrope dunite. High-pressure minerals are predominantly of the ultramafic suite, Cr-association minerals (purplish-red and violet pyrope, chromian spinel, chromian diopside, Cr-pargasite and orthopyroxene). The Ti-association minerals of the ultramafic suite (picroilmenite and orange pyrope), as well as rare grains of orange pyrope-almandine of the eclogite association, are subordinate. Kimberlites from all four pipes contain rare grains of G10 pyrope of the diamond association, but chromian spinel of the diamond association was not encountered. By their tectonic position, by geochemical characteristics, and by the composition of kimberlite indicator minerals, the Fazenda Largo kimberlites, like the others of such type, are unlikely to be economic.

  10. On craton thinning/destruction: Insight from 2D thermal-mechanical numerical modeling

    NASA Astrophysics Data System (ADS)

    Liao, J.

    2014-12-01

    Although most cratons maintain stable, some exceptions are present, such as the North China craton, North Atlantic craton, and Wyoming craton, which have experienced dramatic lithospheric deformation/thinning. Mechanisms triggering cratonic thinning remains enigmatic [Lee et al., 2011]. Using a 2D thermo-mechanical coupled numerical model [Gerya and Yuen, 2007], we investigate two possible mechanisms: (1) stratification of cratonic lithospheric mantle, and (2) rheological weakening due to hydration.Lithospheric mantle stratification is a common feature in cratonic areas which has been demonstrated by geophysical and geochemical studies [Thybo and Perchuc, 1997; Griffin et al., 2004; Romanowicz, 2009; Rychert and Shearer, 2009; Yuan and Romanowicz, 2010]. The influence of lithospheric mantle stratification during craton evolution remains poorly understood. A rheologically weak layer representing hydrated and/or metasomatized composition is implemented in the lithospheric mantle. Our results show that the weak mantle layer changes the dynamics of lithospheric extension by enhancing the deformation of the overlying mantle and crust and inhibiting deformation of the underlying mantle [Liao et al., 2013; Liao and Gerya, 2014]. Modeling results are compared with North China and North Atlantic cratons. Our work indicates that although the presence of a weak layer may not be sufficient to initiate craton deformation, it enhances deformation by lowering the required extensional plate boundary force. Rheological weakening due to hydration is a possible mechanism triggering/enhancing craton deformation, especially for cratons jaxtaposing with a subduction, since water can release from a subducting slab. We investigate the influence of wet mantle flow laws [Hirth and Kohlstedt, 2003], in which a water parameter (i.e. constant water content) is involved. Our results show that wet dislocation alone does not accelerate cratonic deformation significantly. However, if wet diffusion

  11. One View of the Genesis of Cratonic Mantle and Crust

    NASA Astrophysics Data System (ADS)

    Kelemen, P. B.; Jull, M.; Kelly, R.

    2002-12-01

    Kelemen et al. [1] proposed that SiO2-rich, cratonic mantle peridotite xenoliths from Kaapvaal and Siberia had a two stage history. First, they underwent ca. 40% polybaric decompression melting, ending in spinel peridotite facies, to produce depleted, SiO2-poor residues [2]. Second, residues reacted with migrating, felsic melt to become SiO2-rich and light REE-enriched, in accord with previous work [3-5]. Modified melt rose to form continental crust. In this way, cratonic upper mantle and crust may be genetically linked. This differs from theories in which SiO2-rich cratonic mantle formed via high pressure melting and crystal fractionation involving komatiitic melts, with a coincidental relationship between SiO2-rich peridotites and SiO2-rich crust. With regard to Stage 1, average melt removed from primitive mantle [6] to form depleted, SiO2-poor, Archean mantle in Greenland is similar to experimental partial melts at 2.5 to 3 GPa [2]. Also, heavy REE in cratonic peridotite xenoliths are correlated with Ca, suggesting that residual garnet was exhausted early in melting, long before residual clinopyroxene [1]. This, combined with data on melting as a function of pressure [7], yields an average pressure for polybaric melting ca. 3 GPa. Thus, depleted cratonic peridotites recording equilibration pressures greater than 3 GPa have undergone subsolidus pressure increase and garnet growth. Pressure increase could be in response to thickening via tectonic imbrication, pure shear during continental collision, viscous flow in a "mantle wedge", or diapirism of buoyant, depleted residues through dense, subducting, basaltic crust. We will examine these hypotheses in the light of new calculations of the density of cratonic peridotites as a function of P and T. With regard to Stage 2, this provides an explanation for positive correlation between Ni in olivine and modal orthopyroxene, seen in xenolith suites from some kimberlites, and in a global comparison of cratonic xenoliths

  12. Middle Paleozoic kimberlite magmatism in the northeastern Siberian craton

    NASA Astrophysics Data System (ADS)

    Egorova, E. O.; Afanas'ev, V. P.; Pokhilenko, N. P.

    2016-10-01

    The mineral chemistry and crystal morphology of kimberlite pyropes from the Billyakh River placer in the northeastern Siberian craton are characterised in terms of the placer history. The pyropes bear signatures of chemical weathering (dissolution), presumably in a Middle Paleozoic laterite profile, and therefore were originally hosted by Middle Paleozoic kimberlites. The broad occurrence of placer pyropes with lateritic dissolution signatures points to the presence of Middle Paleozoic diamond-bearing kimberlites in the study area.

  13. Construction and destruction of some North American cratons

    NASA Astrophysics Data System (ADS)

    Snyder, David B.; Humphreys, Eugene; Pearson, D. Graham

    2017-01-01

    Construction histories of Archean cratons remain poorly understood; their destruction is even less clear because of its rarity, but metasomatic weakening is an essential precursor. By assembling geophysical and geochemical data in 3-D lithosphere models, a clearer understanding of the geometry of major structures within the Rae, Slave and Wyoming cratons of central North America is now possible. Little evidence exists of subducted slab-like geometries similar to modern oceanic lithosphere in these construction histories. Underthrusting and wedging of proto-continental lithosphere is inferred from multiple dipping discontinuities, emphasizing the role of lateral accretion. Archean continental building blocks may resemble the modern lithosphere of oceanic plateau, but they better match the sort of refractory crust expected to have formed at Archean ocean spreading centres. Radiometric dating of mantle xenoliths provides estimates of rock types and ages at depth beneath sparse kimberlite occurrences, and these ages can be correlated to surface rocks. The 3.6-2.6 Ga Rae, Slave and Wyoming cratons stabilized during a granitic bloom at 2.61-2.55 Ga. This stabilization probably represents the final differentiation of early crust into a relatively homogeneous, uniformly thin (35-42 km), tonalite-trondhjemite-granodiorite crust with pyroxenite layers near the Moho atop depleted lithospheric mantle. Peak thermo-tectonic events at 1.86-1.7 Ga broadly metasomatized, mineralized and recrystallized mantle and lower crustal rocks, apparently making mantle peridotite more 'fertile' and more conductive by introducing or concentrating sulfides or graphite at 80-120 km depths. This metasomatism may have also weakened the lithosphere or made it more susceptible to tectonic or chemical erosion. Late Cretaceous flattening of Farallon lithosphere that included the Shatsky Rise conjugate appears to have weakened, eroded and displaced the base of the Wyoming craton below 140-160 km. This

  14. Isopycnicity, Thermal State and Secular Evolution of Cratonic Mantle Keels

    NASA Astrophysics Data System (ADS)

    Eaton, D. W.; Bastow, I. D.; Kendall, J. M.; Perry, C.

    2010-12-01

    The lithosphere-asthenosphere boundary (LAB) beneath ancient continental nuclei (cratons) is thought to be anomalously deep (> 200 km) due to the presence of cold, compositionally distinct mantle keels that are readily identifiable as high-velocity features in global tomographic models. The empirical concept of isopycnicity, which posits that a pervasive state of near-neutral buoyancy is created by offsetting thermal and compositional effects on density, is often invoked to explain the long-term stability of cratonic mantle keels and general absence of an accompanying long-wavelength gravity signature. Although the concept is appealing, the mechanisms by which an isopycnic state can be sustained are not clear. For example, on a billion-year (Gyr) timescale, secular cooling of a mantle keel could induce a gradual departure from isopycnicity. This possibility is examined by thermal modeling of a cold cratonic keel starting from an approximately isopycnic state near thermal equilibrium. Our models assume that the temperature of the LAB intersects the mantle adiabat, and consider secular cooling (40 K per Gyr) as well as gradual loss of radiogenic heating in the lithosphere. Several scenarios corresponding to ‘average’ Archean and Proterozoic mantle compositions are considered and used to predict seismic and gravitational observables. Our results confirm that, under similar thermal conditions, less-depleted mantle keels of ‘Proterozoic’ composition are less buoyant than Archean keels, but are indistinguishable based on seismic wave velocity. In general, cratonic keels are predicted to founder isostatically at about 1 km / Gyr, which should impose an easily observed epeirogenic signal in the core regions of continents.

  15. Magnesium isotopic variations in cratonic eclogites: Origins and implications

    NASA Astrophysics Data System (ADS)

    Wang, Shui-Jiong; Teng, Fang-Zhen; Williams, Helen M.; Li, Shu-Guang

    2012-12-01

    Cratonic eclogites play an important role in the formation and dynamic evolution of the subcontinental lithospheric mantle. However, their origin, whether as fragments of subducted oceanic crust or high-pressure mantle cumulates, remains controversial. Here, we report Mg isotopic compositions (δ26Mg) for cratonic eclogites from Kaalvallei and Bellsbank kimberlite pipes, South Africa. We find that clinopyroxene is 0.375±0.069 to 0.676±0.075‰ heavier than coexisting garnet, which reflects equilibrium isotope fractionation between these phases, primarily driven by the difference in Mg coordination between clinopyroxene and garnet. Bulk eclogites have strikingly variable Mg isotopic compositions, which range from -0.797±0.075 to -0.139±0.061‰, values that are significantly lighter than the range displayed by global mantle peridotites to date (-0.25±0.07‰, 2SD). As significant Mg isotope fractionation is only known to occur during low-temperature water-rock interaction, our results provide further evidence for the derivation of cratonic eclogites from subducted altered oceanic crust. In addition, the lack of correlation between Δ26Mg and Δ57Fe provides evidence for redox control on equilibrium inter-mineral Fe isotope fractionation.

  16. Electrical lithosphere beneath the Kaapvaal craton, southern Africa

    NASA Astrophysics Data System (ADS)

    Evans, Rob L.; Jones, Alan G.; Garcia, Xavier; Muller, Mark; Hamilton, Mark; Evans, Shane; Fourie, C. J. S.; Spratt, Jessica; Webb, Susan; Jelsma, Hielke; Hutchins, Dave

    2011-04-01

    A regional-scale magnetotelluric (MT) experiment across the southern African Kaapvaal craton and surrounding terranes, called the Southern African Magnetotelluric Experiment (SAMTEX), has revealed complex structure in the lithospheric mantle. Large variations in maximum resistivity at depths to 200-250 km relate directly to age and tectonic provenance of surface structures. Within the central portions of the Kaapvaal craton are regions of resistive lithosphere about 230 km thick, in agreement with estimates from xenolith thermobarometry and seismic surface wave tomography, but thinner than inferred from seismic body wave tomography. The MT data are unable to discriminate between a completely dry or slightly "damp" (a few hundred parts per million of water) structure within the transitional region at the base of the lithosphere. However, the structure of the uppermost ˜150 km of lithosphere is consistent with enhanced, but still low, conductivities reported for hydrous olivine and orthopyroxene at levels of water reported for Kaapvaal xenoliths. The electrical lithosphere around the Kimberley and Premier diamond mines is thinner than the maximum craton thickness found between Kimberley and Johannesburg/Pretoria. The mantle beneath the Bushveld Complex is highly conducting at depths around 60 km. Possible explanations for these high conductivities include graphite or sulphide and/or iron metals associated with the Bushveld magmatic event. We suggest that one of these conductive phases (most likely melt-related sulphides) could electrically connect iron-rich garnets in a garnet-rich eclogitic composition associated with a relict subduction slab.

  17. Seismic structure and dynamics of cratons: Stability and modification, continental collision and subduction

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergei; Meier, Thomas; Schaeffer, Andrew J.; Agius, Matthew R.; Adam, Joanne M.-C.

    2014-05-01

    The Archean crust of stable cratons within today's continents is typically underlain by cold, thick mantle lithosphere. These mechanically strong, compositionally buoyant mantle roots (overall, roughly neutrally buoyant due to the density increase caused by low temperatures) have ensured the survival of cratons since their formation. Global and regional seismic tomography detects cratons readily by the anomalously high seismic velocities within their mantle lithosphere. The increasing resolution of seismic imaging now enables detailed mapping of the locations, boundaries and properties of cratons and offers new insight into their dynamics and evolution. Here, we summarise inferences on cratonic structure and dynamics based on recent multimode-waveform tomography on the global and continental (Europe, N America) scales and from regional, surface-wave array imaging. Where crustal cratonic boundaries can be mapped at the surface, they are, normally, closely matched by the boundaries of the high-velocity (thick and cold) mantle lithosphere beneath. Where the ancient crust is covered by sediments, with crustal block boundaries thus unclear, cratons can be mapped accurately by the seismic imaging of their high-velocity lithosphere. (Important exceptions include cratons that lost their ancient mantle roots in the Phanerozoic, e.g., eastern Sino-Korean Craton). On average, the upper mantle beneath cratons shows shear-wave speeds higher than elsewhere down to depths smaller than 300 km; large shear-speed anomalies are seen down to around 200 km depth only. Layered azimuthal anisotropy within cratonic lithosphere indicates frozen fabric that is probably a record of complex, vertically stratified deformation during the formation and stabilisation of cratons. Lateral variations in seismic velocities within cratonic roots present evidence for their modification and evolution after their formation. Beneath cratons in northern Europe, the locations of kimberlites coincide with

  18. ASTER Images San Francisco Bay Area

    NASA Image and Video Library

    2000-04-26

    This image of the San Francisco Bay region was acquired on March 3, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters about 50 to 300 feet ), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. Image: This image covers an area 60 kilometers (37 miles) wide and 75 kilometers (47 miles) long in three bands of the reflected visible and infrared wavelength region. The combination of bands portrays vegetation in red, and urban areas in gray. Sediment in the Suisun Bay, San Pablo Bay, San Francisco Bay, and the Pacific Ocean shows up as lighter shades of blue. Along the west coast of the San Francisco Peninsula, strong surf can be seen as a white fringe along the shoreline. A powerful rip tide is visible extending westward from Daly City into the Pacific Ocean. In the lower right corner, the wetlands of the South San Francisco Bay National Wildlife Refuge appear as large dark blue and brown polygons. The high spatial resolution of ASTER allows fine detail to be observed in the scene. The main bridges of the area (San Mateo, San Francisco-Oakland Bay, Golden Gate, Richmond-San Rafael, Benicia-Martinez, and Carquinez) are easily picked out, connecting the different communities in the Bay area. Shadows of the towers along the Bay Bridge can be seen over the adjacent bay water. With enlargement the entire road network can be easily mapped; individual buildings are visible, including the shadows of the high-rises in downtown San Francisco. Inset: This enlargement of the San Francisco Airport highlights the high spatial resolution of ASTER. With further enlargement and careful examination, airplanes can be seen at the terminals. http://photojournal.jpl.nasa.gov/catalog/PIA02606

  19. 3. Historic American Buildings Survey deYoung Museum, San Francisco MISSION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Historic American Buildings Survey deYoung Museum, San Francisco MISSION BEFORE 1835 (ORIANA DAY PAINTINGS - (1861 - 1885) - Mission San Francisco de Asis, Mission & Sixteenth Streets, San Francisco, San Francisco County, CA

  20. 7. Historic American Buildings Survey deYoung Museum San Francisco, California ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. Historic American Buildings Survey deYoung Museum San Francisco, California GENERAL VIEW c. 1860 - Mission San Francisco de Asis, Mission & Sixteenth Streets, San Francisco, San Francisco County, CA

  1. 33 CFR 165.1192 - Security Zones; Waters surrounding San Francisco International Airport and Oakland International...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... surrounding San Francisco International Airport and Oakland International Airport, San Francisco Bay... Security Zones; Waters surrounding San Francisco International Airport and Oakland International Airport... Francisco International Airport Security Zone. This security zone includes all waters extending from the...

  2. Assimilation Studies Off Cape Sao Vicente (southern Portugal)

    NASA Astrophysics Data System (ADS)

    Vitorino, J.; Monteiro, M.

    In April 2001 the Portuguese Navy conducted a naval exercise (Swordfish 2001) in the area off Cape Sao Vicente, in the southwest tip of Portugal. The operational environ- mental assessment (OEA) component of this exercise, conducted by Instituto Hidro- grafico, intended to provide forecasts of the oceanographic conditions to the naval forces. A program of observations, which included CTD casts to maximum depth of 2500m and AXBTs casts to maximum depth 1000m, was conducted in the area be- tween 35zN and 39zN and from 7zW to 12.5zW. Forecasts of the oceanographic con- ditions were produced using the Harvard Ocean Prediction System (HOPS) with as- similation of the hydrographic data. The period covered by the exercise was character- ized by predominant southerly winds, forcing upwelling conditions along the western Portuguese coast. These conditions promote the development of a large cold upwelling filament that extended a few hundreds of kilometers southwards Cape Sao Vicente. In this communication we present several results obtained for the period between 18 to 28 April 2001, marked by an event of two days of inversion of the upwelling favor- able. The numerical runs were obtained using two nested domains, one covering the global area of observations and the second one covering the shelf and slope area off Cape Sao Vicente. Double-sigma coordinates were used in both domains, with a total of 20 sigma levels. The surface forcing used the wind fields generated by ALADIN- Portugal, a limited area model (12.7-km grid resolution) nested on a global model (ARPEGE).

  3. Modeling the QBO and SAO Driven by Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Chan, K. L.; Porter, H. S.

    1999-01-01

    Hines' Doppler spread parameterization (DSP) for small scale gravity waves (GW) is applied in a global scale numerical spectral model (NSM) to describe the semi-annual and quasi-biennial oscillations (SAO and QBO) as well as the long term interannual variations that are driven by wave mean flow interactions. This model has been successful in simulating the salient features observed near the equator at altitudes above 20 km, including the QBO extension into the upper mesosphere inferred from UARS measurements. The model has now been extended to describe also the mean zonal and meridional circulations of the upper troposphere and lower stratosphere that affect the equatorial QBO and its global scale extension. This is accomplished in part through tuning of the GW parameterization, and preliminary results lead to the following conclusions: (1) To reproduce the upwelling at equatorial latitudes associated with the Brewer/Dobson circulation that in part is modulated in the model by the vertical component of the Coriolis force, the eddy diffusivity in the lower stratosphere had to be enhanced and the related GW spectrum modified to bring it in closer agreement with the form recommended for the DSP. (2) To compensate for the required increase in the diffusivity, the observed QBO requires a larger GW source that is closer to the middle of the range recommended for the DSP. (3) Through global scale momentum redistribution, the above developments are conducive to extending the QBO and SAO oscillations to higher latitudes. Multi-year interannual oscillations are generated through wave filtering by the solar driven annual oscillation in the zonal circulation. (4) In a 3D version of the model, wave momentum is absorbed and dissipated by tides and planetary waves. Thus, a somewhat larger GW source is required to generate realistic amplitudes for the QBO and SAO.

  4. The young active star SAO 51891 (V383 Lacertae)

    NASA Astrophysics Data System (ADS)

    Biazzo, K.; Frasca, A.; Marilli, E.; Covino, E.; Alcalã, J. M.; Ćakirli, Ö.; Klutsch, A.; Meyer, M. R.

    2009-05-01

    Aims: The aim of this work is to investigate the surface inhomogeneities of a young, late-type star, SAO 51891, at different atmospheric levels, from the photosphere to the upper chromosphere, analyzing contemporaneous optical high-resolution spectra and broad-band photometry. Methods: The full spectral range of FOCES@CAHA (R ≃ 40 000) is used to perform the spectral classification and to determine the rotational and radial velocities. The lithium abundance is measured to obtain an age estimate. The {BVRIJHK}s photometric bands are used to construct the spectral energy distribution (SED). The variations in the observed BV fluxes and effective temperature are used to infer the presence of photospheric spots and observe their behavior over time. The chromospheric activity is studied applying the spectral subtraction technique to Hα, Ca ii H & K, Hɛ, and Ca ii IRT lines. Results: We find SAO 51891 to be a young K0-1V star with a lithium abundance close to the Pleiades upper envelope, confirming its youth ( 100 Myr), which is also inferred from its kinematical membership of the Local Association. No infrared excess is detected from analysis of its SED, limiting the amount of remaining circumstellar dust. We detect a rotational modulation of the luminosity, effective temperature, Ca ii H & K, Hɛ, and Ca ii IRT total fluxes. A simple spot model with two main active regions, about 240 K cooler than the surrounding photosphere, fits the observed light and temperature curves very well. The small-amplitude radial velocity variations are also well reproduced by our spot model. The anti-correlation of light curves and chromospheric diagnostics indicates chromospheric plages spatially associated with the spots. The largest modulation amplitude is observed for the Hɛ flux suggesting that this line is very sensitive to the presence of chromospheric plages. Conclusions: SAO 51891 is a young active star, lacking significant amounts of circumstellar dust or any evidence of low

  5. Analysis of Deuteron-Nucleus Scattering Using Sao Paulo Potential

    NASA Astrophysics Data System (ADS)

    Ibraheem, Awad A.

    2016-12-01

    Deuteron elastic and inelastic scattering from 6Li, 12C, 16O, 24Mg, 32S, 50V, 58Ni, 70Ge, 90Zr, and 116Sn targets at different incident energies have been analyzed. Both Phenomenological Woods-Saxon and double-folding optical model potentials have been used. The folding calculations were based upon the Sao Paulo potential. A semi-microscopic representation has been proposed to study the effect of the dynamic polarization potential. Comparisons between our results and measured angular distributions of the differential cross sections showed a pronounced success of our theoretical predictions. The corresponding reaction cross sections have also been investigated.

  6. Geothermal resources of Sao Miguel Island, Azores, Portugal

    SciTech Connect

    Duffield, W.A.; Muffler, L.J.P.

    1984-01-01

    Geothermal studies were carried out on the island of Sao Miguel, Azores to characterize the nature of the resource, to estimate its magnitude, and to identify target areas toward which exploration and developmental drilling might be directed. The main geothermal resource areas are Furnas, Agua de Pau, and Sete Cidades, three Quaternary silicic volcanic centers characterized by summit calderas beneath which magmatic heat sources provide thermal energy to overlying hydrothermal convection systems. For each of the systems, the studies have defined the size of the system, the subsurface temperature, the thermodynamic state of fluid in the system, the chemical composition of the fluid, and permeable parts of the system. 8 figs. (ACR)

  7. Dating brittle deformation in the Archean Yilgarn Craton, Western Australia

    NASA Astrophysics Data System (ADS)

    Thebaud, N.; Zwingmann, H.

    2012-12-01

    Major deformation throughout the Archean Yilgarn Craton has mostly been interpreted to be Neoarchean (Blewett and Czarnota, 2007). The timing of the deformation events of the brittle/ductile deformation generally relies on dating of cross-cutting intrusions or unconformities. Proterozoic overprinting and reactivation of Archean structures in the north-western part of the Yilgarn Craton has previously been dated from direct dating of the structures and fabrics from the Narryer Terrane(Spaggiari et al., 2008). However, the brittle deformation that postdates Neoarchean brittle-ductile structures in the Yilgarn Craton have received little attention to date. In the centre of the Yilgarn Craton, the Eastern Goldfields present a well developed network of E-W trending of normal brittle faults and fractures. Typically these structures are interpreted to have developed in result of a late Neoarchean tectonic relaxation following the main Yilgarn wide E-W contraction (Blewett and Czarnota, 2007). Poorly preserved and weathered faulted rocks in the subsurface environment preclude direct dating of fault gouge. However, exposure from the underground Agnew mine, in the Agnew Wiluna greenstone belt, recently provided access to fresh fault gouge material suitable for analysis. The clay gouge was characterized by SEM, TEM and XRD methods prior to age dating indicating an authigenic origin (Zwingmann et al., 2010). K-Ar illite age data of a whole rock sample split yielded an age of 1148 ± 23 Ma, which is within error close to the <2 micron clay fraction yielding an age of 1094 ± 22 Ma (Mesoproterozoic-Stenian). Our result is the first documentation of the age of the brittle deformation that affects the Yilgarn Craton. This age is within error of the Gilles event which is an extension event that affected the whole Australian continent and is responsible for the emplacement of the Warakurna Large Igneous Province and related dolerite dykes in the Yilgarn Craton (Evins et al., 2010

  8. Space Radar Image of San Francisco, California

    NASA Image and Video Library

    1999-05-01

    This is a radar image of San Francisco, California, taken on October 3,1994. The image is about 40 kilometers by 55 kilometers (25 miles by 34 miles) with north toward the upper right. Downtown San Francisco is visible in the center of the image with the city of Oakland east (to the right) across San Francisco Bay. Also visible in the image is the Golden Gate Bridge (left center) and the Bay Bridge connecting San Francisco and Oakland. North of the Bay Bridge is Treasure Island. Alcatraz Island appears as a small dot northwest of Treasure Island. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on orbit 56. The image is centered at 37 degrees north latitude, 122degrees west longitude. This single-frequency SIR-C image was obtained by the L-band (24 cm) radar channel, horizontally transmitted and received. Portions of the Pacific Ocean visible in this image appear very dark as do other smooth surfaces such as airport runways. Suburban areas, with the low-density housing and tree-lined streets that are typical of San Francisco, appear as lighter gray. Areas with high-rise buildings, such as those seen in the downtown areas, appear in very bright white, showing a higher density of housing and streets which run parallel to the radar flight track. http://photojournal.jpl.nasa.gov/catalog/PIA01751

  9. Smad7 mediates inhibition of Saos2 osteosarcoma cell differentiation by NF{kappa}B

    SciTech Connect

    Eliseev, Roman A. . E-mail: Roman_Eliseev@urmc.rochester.edu; Schwarz, Edward M.; Zuscik, Michael J.; O'Keefe, Regis J.; Drissi, Hicham; Rosier, Randy N.

    2006-01-01

    The transcription factor NF{kappa}B is constitutively activated in various tumor cells where it promotes proliferation and represses apoptosis. The bone morphogenetic proteins (BMPs) delay cell proliferation and promote differentiation and apoptosis of bone cells through activation of Smad downstream effectors and via Smad-independent mechanisms. Thus, NF{kappa}B and BMP pathways play opposing roles in regulating osteoblastic cell fate. Here, we show that in osteosarcoma Saos2 osteoblasts, NF{kappa}B regulates the activity of the BMP/Smad signaling. Inhibition of NF{kappa}B by overexpression of mI{kappa}B leads to the induction of osteoblast differentiation. Saos2 cells overexpressing mI{kappa}B (Saos2-mI{kappa}B) exhibit higher expression of osteoblast phenotypic genes such as alkaline phosphatase, Runx2 and osteocalcin and are more responsive to BMP2 in comparison to wild-type cells (Saos2-wt) or empty vector infected controls (Saos2-EV). Furthermore, BMP-2 signaling and Smad phosphorylation are significantly increased in Saos2-mI{kappa}B cells in comparison to Saos2-EV cells. Inhibition of NF{kappa}B signaling in Saos2-mI{kappa}B cells is associated with decreased expression of the BMP signaling inhibitor Smad7. While gain of Smad7 function in Saos2-mI{kappa}B cells results in inhibition of BMP signaling, anti-sense knockdown of Smad7 in Saos2-EV cells leads to upregulation of BMP signaling. We therefore conclude that in osteosarcoma Saos2 cells, NF{kappa}B represses BMP/Smad signaling and BMP2-induced differentiation through Smad7.

  10. 40. Historic American Buildings Survey San Francisco Chronicle Collection San ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. Historic American Buildings Survey San Francisco Chronicle Collection San Francisco, California March 24, 1924 VIEW OF HIGH ALTAR - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

  11. 19. Photocopy of photograph (from De Young Museum, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Photocopy of photograph (from De Young Museum, San Francisco, California, late 1890's) EXTERIOR, GENERAL VIEW OF MISSION, LATE 1890'S - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  12. 18. Photocopy of photograph (from De Young Museum, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. Photocopy of photograph (from De Young Museum, San Francisco, California, 1895) EXTERIOR, SOUTH FRONT OF MISSION AND CONVENTO, 1895 - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  13. 13. Photocopy of photograph (from Golden Gate Museum, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Photocopy of photograph (from Golden Gate Museum, San Francisco, California, 1850's) EXTERIOR, VIEW OF CONVENTO BEFORE RESTORATION, 1850'S - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  14. 5. Photocopy of painting (from De Young Museum, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. Photocopy of painting (from De Young Museum, San Francisco, California, Oriana Day, artist, c. 1861-1885) EXTERIOR VIEW OF MISSION BEFORE 1835 - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  15. 6. Photocopy of painting (from California Historical Society, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of painting (from California Historical Society, San Francisco, California, Oriana Day, artist, 1879) EXTERIOR, VIEW FROM AN ANGLE OF MISSION AND SURROUNDING STRUCTURES - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  16. A Glorious Century of Art Education: San Francisco's Art Institute

    ERIC Educational Resources Information Center

    Dobbs, Stephen Mark

    1976-01-01

    Author described the life and times of the San Francisco Art Institute and reviewed the forces that made San Francisco a city of more than ordinary awareness of the arts in its civic and civil existence. (Editor/RK)

  17. Medical genetics services in the city of Sao Paulo, Brazil.

    PubMed

    Brunoni, Decio

    2004-01-01

    The city of Sao Paulo is located in the center of a metropolitan area with nearly 18 million inhabitants and 300,000 births/year. The currently existing medical genetics services are unable to meet the demand, due to their insufficient physical and personnel infrastructure. Institutions and experts in medical genetics could give short training and refresher courses to health professionals to enable them to work in the public health network. The city has a reasonably well developed health care network, represented by the Single Health System (Sistema Unico de Saude - SUS) and by the Family Health Program (Programa de Saude da Familia - PSF). The financial resources for such actions originate in the budget of the managing agencies of such systems. The limitations of genetic services provided to the population of the city could be overcome in a short period of time by developing programs within the public health care network. The city has institutions, professionals and financial resources to make this project feasible. To that end, the competent authorities of the Sao Paulo State and City Secretariats of Health should take managerial responsibility for the genetic services in the city. Copyright (c) 2004 S. Karger AG, Basel.

  18. Caesarean sections and maternal mortality in Sao Paulo.

    PubMed

    Kilsztajn, Samuel; Carmo, Manuela S N do; Machado, Luis C; Lopes, Erika S; Lima, Luciana Z

    2007-05-01

    To evaluate caesarean section in both public and private sectors; maternal mortality associated with mode of delivery in the public sector (Sistema Unico de Saude, SUS) in Sao Paulo State, Brazil. 610,630 births in both public and private sectors for 2003; 1,153,034 deliveries and 314 maternal deaths in the public sector for 2001-2003. The study estimated caesarean section rates and odds ratios for caesarean section in association with maternal characteristics in both public and private sectors; maternal mortality associated with mode of delivery in the public sector, adjusted for hypertension, other disorders, problems and complications, as well as maternal age. The caesarean section rate was 32.9% in the public sector, and 80.4% in the private sector. The odd ratio for caesarean section was 2.6 (95% CI: 2.6-2.7) for women with 12 or more years of education. The odd ratio for maternal mortality associated with caesarean section in the public sector was 3.3 (95% CI: 2.6-4.3). Sao Paulo presented high caesarean section rates. Caesarean section compared to vaginal delivery in the public sector presented higher risk for mortality even when adjusted for hypertension, other disorders, problems and complications, as well as maternal age.

  19. GiSAO.db: a database for ageing research.

    PubMed

    Hofer, Edith; Laschober, Gerhard T; Hackl, Matthias; Thallinger, Gerhard G; Lepperdinger, Günter; Grillari, Johannes; Jansen-Dürr, Pidder; Trajanoski, Zlatko

    2011-05-24

    Age-related gene expression patterns of Homo sapiens as well as of model organisms such as Mus musculus, Saccharomyces cerevisiae, Caenorhabditis elegans and Drosophila melanogaster are a basis for understanding the genetic mechanisms of ageing. For an effective analysis and interpretation of expression profiles it is necessary to store and manage huge amounts of data in an organized way, so that these data can be accessed and processed easily. GiSAO.db (Genes involved in senescence, apoptosis and oxidative stress database) is a web-based database system for storing and retrieving ageing-related experimental data. Expression data of genes and miRNAs, annotation data like gene identifiers and GO terms, orthologs data and data of follow-up experiments are stored in the database. A user-friendly web application provides access to the stored data. KEGG pathways were incorporated and links to external databases augment the information in GiSAO.db. Search functions facilitate retrieval of data which can also be exported for further processing. We have developed a centralized database that is very well suited for the management of data for ageing research. The database can be accessed at https://gisao.genome.tugraz.at and all the stored data can be viewed with a guest account.

  20. Craton stability and continental lithosphere dynamics during plume-plate interaction

    NASA Astrophysics Data System (ADS)

    Wang, H.; Van Hunen, J.; Pearson, D.

    2013-12-01

    Survival of thick cratonic roots in a vigorously convecting mantle system for billions of years has long been studied by the geodynamical community. A high cratonic root strength is generally considered to be the most important factor. We first perform and discuss new numerical models to investigate craton stability in both Newtonian and non-Newtonian rheology in the stagnant lid regime. The results show that only a modest compositional rheological factor of Δη=10 with non-Newtonian rheology is required for the survival of cratonic roots in a stagnant lid regime. A larger rheological factor (100 or more) is needed to maintain similar craton longevity in a Newtonian rheology environment. Furthermore, chemical buoyancy plays an important role on craton stability and its evolution, but could only work with suitable compositional rheology. During their long lifespan, cratons experienced a suite of dynamic, tectonothermal events, such as nearby subduction and mantle plume activity. Cratonic nuclei are embedded in shorter-lived, more vulnerable continental areas of different thickness, composition and rheology, which would influence the lithosphere dynamic when tectonothermal events happen nearby. South Africa provides a very good example to investigate such dynamic processes as it hosts several cratons and there are many episodic thermal events since the Mesozoic as indicated by a spectrum of magmatic activity. We numerically investigate such an integrated system using the topographic evolution of cratons and surrounding lithosphere as a diagnostic observable. The post-70Ma thinning of pericratonic lithosphere by ~50km around Kaapvaal craton (Mather et al., 2011) is also investigated through our numerical models. The results show that the pericratonic lithosphere cools and grows faster than cratons do, but is also more likely to be effected by episodic thermal events. This leads to surface topography change that is significantly larger around the craton than within

  1. A Cooperative Project for Electrical Engineering Education at UNESP--Sao Paulo State University.

    ERIC Educational Resources Information Center

    Akamatsu, Janio Itiro; Torres, Germano Lambert; Origa de Oliveira, Luiz C.; Loyolla, Waldomiro

    UNESP--Sao Paulo State University--is a successful experiment at the Multicampus University in Brazil, maintaining intense and diversified education activities in the most developed state of the Federation, the Sao Paulo State. The multicampus structure that consists of 15 university campuses and two advanced ones, distributed throughout the State…

  2. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This cloud free color infrared view of San Francisco and Bay Area, CA (38.0N, 122.5W) is unusual because the city is normally concealed from view by clouds and fog. Gray tones represent urban areas and the red toned areas are vegetated. Within the city, parks easily stand out from the well-developed parts of the city as enclaves of color. The trace of the San Andreas fault shows as a straight valley running across the San Francisco peninsula.

  3. The San Francisco volcanic field, Arizona

    USGS Publications Warehouse

    Priest, S.S.; Duffield, W.A.; Malis-Clark, Karen; Hendley, J. W.; Stauffer, P.H.

    2001-01-01

    Northern Arizona's San Francisco Volcanic Field, much of which lies within Coconino and Kaibab National Forests, is an area of young volcanoes along the southern margin of the Colorado Plateau. During its 6-million-year history, this field has produced more than 600 volcanoes. Their activity has created a topographically varied landscape with forests that extend from the Pi?on-Juniper up to the Bristlecone Pine life zones. The most prominent landmark is San Francisco Mountain, a stratovolcano that rises to 12,633 feet and serves as a scenic backdrop to the city of Flagstaff.

  4. San Francisco Bay Long Term Management Strategy for Dredging

    EPA Pesticide Factsheets

    The San Francisco Bay Long Term Management Strategy (LTMS) is a cooperative effort to develop a new approach to dredging and dredged material disposal in the San Francisco Bay area. The LTMS serves as the Regional Dredging Team for the San Francisco area.

  5. [Sanitary battles and scientific clashes: Emilio Ribas and yellow fever in Sao Paulo].

    PubMed

    Almeida, M

    Emilio Ribas, an administrative physician and sanitarian from Sao Paulo, was an advocate of the microbiological conception during the long period when he directed the Servico Sanitario de Sao Paulo (1898-1917). This article offers a brief analysis of his stance in the flight against yellow fever during the early 20th century, considered a highlight of his career. The scientists and professionals linked to this sanitary agency in Sao Paulo found themselves in a tense, unstable work environment, where experimental proof played an important role in corroborating new medical-sanitary conceptions and practices. The article takes a close look at the medical experiments on yellow fever directed by Emilio Ribas and conducted at Sao Paulo's Hospital de Isolamento in 1902-03. It examines these same studies in an effort to better understand how the significance of yellow fever was transformed and to explore its implications regarding the history of public health in Sao Paulo.

  6. The establishment and characterization of adriamycin-resistant cell lines derived from Saos-2.

    PubMed

    Niu, Bao-Hua; Wang, Jian-Jun; Xi, Yan; Ji, Xin-Ying

    2010-06-01

    The aim was to establish and characterize adriamycin (ADM)-resistant cell lines. Two cell lines, named Saos-2/ADM1 and Saos-2/ADM4, resistant to ADM, were established after 167 days. The resistance indices of methotrexate for the Saos-2/ADM1 and Saos-2/ADM4 cell lines to ADM were 49.8 and 74.6 times higher, respectively, than that of Saos-2. The two cells lines had resistance to MTX, IFO, EPI, THP, and PTX, while the cells were found to remain sensitive to cisplatin. Disordered and coenocytic structure were observed via microscopy. This is the first report on ADM-resistant cells based on clinical peak doses in serum. MDR1 and MRP genes are involved in the resistance of cell lines to ADM, which are invaluable tools to study the resistance of anticancer drugs and to find the means to revert the resistance.

  7. Teleseismic receiver functions modeling of the eastern Indian craton

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik; Biswas, Koushik

    2016-09-01

    We estimate receiver functions (RFs) through the time-domain deconvolution using three-component broadband data of 100 teleseismic events (30° ⩽ ∧ ⩽ 90°) from 15 seismographs in the eastern Indian craton. Estimated radial RFs show a positive phase at 4.6-5.8 s delay time corresponding to the crustal thicknesses of 37-46 km. Through the differential evolution (DE) waveform inversion modeling of radial receiver functions, we delineate the crustal structure at 15 broadband stations. On an average, the Archean Singhbhum Odisha Craton (SOC) is characterized by a thick crust of 43 ± 3 km in comparison to a relatively thin crust of 41 ± 1 km underlying the Proterozoic Chotanagpur Granite Gneissic terrain (CGGT). While, a thin crust of 38 ± 1 km characterizes the younger Eastern Ghats Mobile Belt (EGMB). The main results of our modeling reveal a 46 km thick Archean crust underlying the Singhbhum granite (SG) of 3.6 Ga, which is characterized by a 3 km crustal thickening probably resulted from the Archean subduction process. Our modeling also detects a 2-3 km crustal thinning with the thinnest crust of 37 km below the region near South Singhbhum Shear Zone, which could be attributed to the 1.6 Ga plume activity associated with Dalma volcanic. Our modeling also led to the delineation of a crustal thinning of 2-3 km underlying the region in EGMB, which was influenced by a much younger (∼117 Ma) Rajmahal magmatism associated with the Gondwana break-up episode. However, our study could not detect any age-dependent variation of crustal thicknesses in the eastern Indian craton. The main result of our modeling suggests a two-phase crustal evolution process for the SOC viz. older E-W crustal thickening due to E-W plate compression and later crustal thinning episodes associated with the Dalma volcanism in the north and the Rajmahal volcanism in the South.

  8. Stratification of Azimuthal Anisotropy in the North American Craton (Invited)

    NASA Astrophysics Data System (ADS)

    Romanowicz, B. A.; Yuan, H.; Ford, H. A.; Fischer, K. M.; Abt, D.

    2010-12-01

    We present the results of a tomographic study of azimuthal anisotropy using jointly long period teleseismic waveforms and SKS splitting measurements, which reveals the presence of two distinct lithospheric layers throughout the stable part of the North American continent. The top layer is thick (~150 km) under the oldest, Archean core and tapers out on the Paleozoic borders. Its thickness variations are consistent with those inferred for a highly depleted Archean lithospheric layer from thermo-barometric analysis of xenoliths. It is thickest in ancient collision zones (e.g. Trans-Hudson orogen) and thins out under the mid-continental rift zone. The orientation of azimuthal anisotropy in layer 1 follows that of ancient suture zones. In the bottom lithospheric layer, azimuthal anisotropy aligns consistently in a north-south direction, ruling out a possible formation by underplating of a giant plume. The lithosphere-asthenosphere boundary (LAB) is relatively flat (180-240km), consistent with predictions from geodynamical modeling of a thermal conductive root that subsequently formed around the depleted chemical layer. Below the LAB, anisotropy aligns with absolute plate motion, confirming previous work (Marone and Romanowicz, 2007). Our findings tie together seismological, geochemical and geodynamical studies of the cratonic lithosphere in north America. They also reconcile results of seismic tomography and other geophysical studies with recent receiver function studies, which detect structural boundaries under cratons at depths that better correspond to the sharp mid-lithospheric boundary than to the more gradual LAB. In particular, Sp receiver functions under the north American craton detect a sharp mid-lithospheric boundary that, in general, correlates in depth with that found from changes in the direction of azimuthal anisotropy.

  9. Latest Jurassic-early Cretaceous regressive facies, northeast Africa craton

    SciTech Connect

    van Houten, F.B.

    1980-06-01

    Nonmarine to paralic detrital deposits accumulated in six large basins between Algeria and the Arabo-Nubian shield during major regression in latest Jurassic and Early Cretaceous time. The Ghadames Sirte (north-central Libya), and Northern (Egypt) basins lay along the cratonic margin of northeastern Africa. The Murzuk, Kufra, and Southern (Egypt) basins lay in the south within the craton. Data for reconstructing distribution, facies, and thickness of relevant sequences are adequate for the three northern basins only. High detrital influx near the end of Jurassic time and in mid-Cretaceous time produced regressive nubian facies composed largely of low-sinuosity stream and fahdelta deposits. In the west and southwest the Ghadames, Murzuk, and Kufra basins were filled with a few hundred meters of detritus after long-continued earlier Mesozoic aggradation. In northern Egypt the regressive sequence succeeded earlier Mesozoic marine sedimentation; in the Sirte and Southern basins correlative deposits accumulated on Precambrian and Variscan terranes after earlier Mesozoic uplift and erosion. Waning of detrital influx into southern Tunisia and adjacent Libya in the west and into Israel in the east initiated an Albian to early Cenomanian transgression of Tethys. By late Cenomanian time it had flooded the entire cratonic margin, and spread southward into the Murzuk and Southern basins, as well as onto the Arabo-Nubian shield. Latest Jurassic-earliest Cretaceous, mid-Cretaceous, and Late Cretaceous transgressions across northeastern Africa recorded in these sequences may reflect worldwide eustatic sea-level rises. In contrast, renewed large supply of detritus during each regression and a comparable subsidence history of intracratonic and marginal basins imply regional tectonic control. 6 figures.

  10. Remobilization in the cratonic lithosphere recorded in polycrystalline diamond

    PubMed

    Jacob; Viljoen; Grassineau; Jagoutz

    2000-08-18

    Polycrystalline diamonds (framesites) from the Venetia kimberlite in South Africa contain silicate minerals whose isotopic and trace element characteristics document remobilization of older carbon and silicate components to form the framesites shortly before kimberlite eruption. Chemical variations within the garnets correlate with carbon isotopes in the diamonds, indicating contemporaneous formation. Trace element, radiogenic, and stable isotope variations can be explained by the interaction of eclogites with a carbonatitic melt, derived by remobilization of material that had been stored for a considerable time in the lithosphere. These results indicate more recent formation of diamonds from older materials within the cratonic lithosphere.

  11. Synchroneity of cratonic burial phases and gaps in the kimberlite record: Episodic magmatism or preservational bias?

    NASA Astrophysics Data System (ADS)

    Ault, Alexis K.; Flowers, Rebecca M.; Bowring, Samuel A.

    2015-01-01

    A variety of models are used to explain an apparent episodicity in kimberlite emplacement. Implicit in these models is the assumption that the preserved kimberlite record is largely complete. However, some cratons now mostly devoid of Phanerozoic cover underwent substantial Phanerozoic burial and erosion episodes that should be considered when evaluating models for global kimberlite distributions. Here we show a broad temporal coincidence between regional burial phases inferred from thermochronology and gaps in the kimberlite record in the Slave craton, Superior craton, and cratonic western Australia. A similar pattern exists in the Kaapvaal craton, although its magmatic, deposition, and erosion history differs in key ways from the other localities. One explanation for these observations is that there is a common cause of cratonic subsidence and suppression of kimberlite magmatism. Another possibility is that some apparent gaps in kimberlite magmatism are preservational artifacts. Even if kimberlites occurred during cratonic burial phases, the largest uppermost portions of the pipes would have been subsequently eroded along with the sedimentary rocks into which they were emplaced. In this model, kimberlite magmatism was more continuous than the preserved record suggests, implying that evidence for episodicity in kimberlite genesis should be carefully evaluated in light of potential preservational bias effects. Either way, the correlation between burial and kimberlite gaps suggests that cratonic surface histories are important for understanding global kimberlite patterns.

  12. 33 CFR 165.T11-534 - Safety zone; Bay Bridge construction, San Francisco Bay, San Francisco, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Safety zone; Bay Bridge construction, San Francisco Bay, San Francisco, CA. 165.T11-534 Section 165.T11-534 Navigation and Navigable... Eleventh Coast Guard District § 165.T11-534 Safety zone; Bay Bridge construction, San Francisco Bay, San...

  13. 77 FR 37603 - Safety Zone; San Francisco Independence Day Fireworks Display, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-22

    ... Captain of the Port, San Francisco area of responsibility during the dates and times noted below. This action is necessary to protect life and property of the maritime public from the hazards associated...

  14. San Francisco's New Zoo's Connections for Conservation.

    ERIC Educational Resources Information Center

    Routman, Emily

    2001-01-01

    Provides information on a redevelopment project at the San Francisco Zoo known as the New Zoo. The explicit goal of the project is to inspire a sense of caring and appreciation for wildlife that is the foundation of a conservation ethic. (DDR)

  15. San Francisco and Bay Area, CA, USA

    NASA Image and Video Library

    1991-05-06

    STS039-151-181A (28 April-6 May 1991) --- Large format (five-inch) frame of the San Francisco/Oakland Bay Area of northern California. Stratus clouds at 35,000 feet and cumulus clouds at about 15,000 feet are seen over the Pacific Coast, obscuring the Golden Gate Bridge.

  16. Potamocorbula amurensis discovered in San Francisco Bay

    USGS Publications Warehouse

    Schemel, Laurence E.

    1989-01-01

    The small Asian clam, Potamocorbula amurensis, is now a major component of benthic communities in most areas of northern San Francisco Bay and some areas of South Bay. Because of its wide tolerance of salinity and other environmental variables and its high abundance in many areas, benthic ecologists believe this recent invasion may represent a major and permanent change in the bay system.

  17. San Francisco, California: Solar in Action (Brochure)

    SciTech Connect

    Not Available

    2011-10-01

    This brochure provides an overview of the challenges and successes of San Francisco, CA, a 2007 Solar America City awardee, on the path toward becoming a solar-powered community. Accomplishments, case studies, key lessons learned, and local resource information are given.

  18. Civil Service College in San Francisco.

    ERIC Educational Resources Information Center

    Samii, Farhad

    1978-01-01

    The Civil Service College in San Francisco provides preentry level training, inservice training, and promotional training for public employment. The free classes are open to the general public and cover five curriculum areas: supervision and management, clerical and secretarial, communication, community service, and technical. (MB)

  19. Simulations of the 1906 San Francisco Earthquake

    SciTech Connect

    Rodgers, A; Petersson, A; Tkalcic, H

    2005-12-16

    Simulations of the Great 1906 San Francisco earthquake are being performed as part of the event's centenary. LLNL is participating in a large effort to study this event and possible consequences if the event were to happen today. This document is meant to describe our efforts to others participating in the project.

  20. The Third International San Francisco Book Fair.

    ERIC Educational Resources Information Center

    Kalmon, Winn; And Others

    Friends of Books and Comics presents its catalog of the Third International San Francisco Book Fair, a marketplace of alternative books, comics, and magazines. Nearly 200 alternative and small presses are listed alphabetically with address, telephone number, names of principal people involved, and a brief description of type and subject of…

  1. The Third International San Francisco Book Fair.

    ERIC Educational Resources Information Center

    Kalmon, Winn; And Others

    Friends of Books and Comics presents its catalog of the Third International San Francisco Book Fair, a marketplace of alternative books, comics, and magazines. Nearly 200 alternative and small presses are listed alphabetically with address, telephone number, names of principal people involved, and a brief description of type and subject of…

  2. Lick-Wilmerding School San Francisco, California.

    ERIC Educational Resources Information Center

    Fang, Eric C. Y.

    1997-01-01

    Examines the design of a new library/art facility at a San Francisco high school that complemented the school's contemporary academic program and reputation for excellence. Discusses the planning and architectural strategies and the technological and convenience additions designed to meet greater student needs. (GR)

  3. The Sao Paulo Microtron: Equipment and Planned Experiments

    SciTech Connect

    Martins, M. N.; Maidana, N. L.; Vanin, V. R.

    2007-10-26

    The Linear Accelerator Laboratory (LAL) of the Instituto de Fisica da Universidade de Sao Paulo (IFUSP) is building a two-stage racetrack microtron, which will generate continuous wave electron beams with energies up to 38 MeV. This paper describes the characteristics of the accelerator, and reports on the experimental equipment that will be available in order to pursue the photonuclear physics research program. Operation will begin with the first stage (5 MeV), and concentrate on NRF (Nuclear Resonance Fluorescence) measurements and radiation physics studies. Planned experiments for the second stage explore the cw character of the beam on coincidence experiments. A photon tagger has been already tested with radioactive sources and is ready to be installed. Gamma and neutron detector arrays are being developed for the detailed study of photoneutron reactions. Plans include the study of NRF and pygmy resonances, near the neutron binding energy.

  4. [Demographic discontinuities in Brazil and the state of Sao Paulo].

    PubMed

    Bercovich, A; Madeira, F

    1994-06-01

    "Given the importance of information on the population age structure when planning short, medium and long-term needs within the different social strata, this paper is a proposal to deepen...the study of changes in the population pyramids.... Based on the most recent methodologies a study of age discontinuities is carried out and a method of follow-up by cohorts is suggested, taking the 15-19 and 20-24 age groups as an example. The purpose is to show that, as a...cohort ascends in the age pyramid, new and different necessities arise and also different responses are demanded on the part of the social system." Data are for Brazil as a whole and for the state of Sao Paulo. (SUMMARY IN ENG) excerpt

  5. Salt Ponds, South San Francisco Bay

    NASA Technical Reports Server (NTRS)

    2002-01-01

    higher resolution 1000 pixel-wide image The red and green colors of the salt ponds in South San Francisco Bay are brilliant visual markers for astronauts. The STS-111 crew photographed the bay south of the San Mateo bridge in June, 2002. This photograph is timely because a large number of the salt ponds (more than 16,500 acres) that are owned by Cargill, Inc. will be sold in September for wetlands restoration-a restoration project second in size only to the Florida Everglades project. Rough boundaries of the areas to be restored are outlined on the image. Over the past century, more than 80% of San Francisco Bay's wetlands have been filled and developed or diked off for salt mining. San Francisco Bay has supported salt mining since 1854. Cargill has operated most of the bay's commercial salt ponds since 1978, and had already sold thousands of acres to the State of California and the Don Edwards National Wildlife Refuge. This new transaction will increase San Francisco Bay's existing tidal wetlands by 50%. The new wetlands, to be managed by the California Department of Fish and Game and the U.S. Fish and Wildlife Service, will join the Don Edwards National Wildlife Refuge, and provide valuable habitat for birds, fish and other wildlife. The wetlands will contribute to better water quality and flood control in the bay, and open up more coastline for public enjoyment. Additional information: Cargill Salt Ponds (PDF) Turning Salt Into Environmental Gold Salt Ponds on Way to Becoming Wetlands Historic Agreement Reached to Purchase San Francisco Bay Salt Ponds Astronaut photograph STS111-376-3 was provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth

  6. Upper mantle P velocities beneath the North America craton

    NASA Astrophysics Data System (ADS)

    Chu, R.; Helmberger, D. V.

    2010-12-01

    In this work, we determined the detailed mechanisms of three earthquakes occurring in Quebec, Texas and Idaho for use in modeling triplication data. The first event provided pure-path triplication recordings at over 400 USArray stations. Although amplitudes of the direct P waves are small, the depth phase sP is clear and displays shadow-zone characteristics indicative a low velocity layer (LVL) in the upper mantle, where the amplitude of the AB branch decreases rapidly at a distance of 16 degrees. Another feature of the LVL is that the AB branch can be seen at distances larger than 23 degrees. Similar to the Canadian Shield velocity model S25 (LeFevre and Helmberger, 1989), we found a LVL between 160 km and 215 km and obtained excellent fits assuming 1D model. The other two events are located near the craton margins and have been recorded by the MOMA array (Texas event) and CANOE array (Idaho event). These mixed paths are mostly craton with modified 1D models producing good fits. We, also, produced 2D modeling results that use tomographic images for correcting the source structures.

  7. Properties of QBO and SAO Generated by Gravity Waves

    NASA Technical Reports Server (NTRS)

    Mayr, H. G.; Mengel, J. G.; Reddy, C. A.; Chan, K. L.; Porter, H. S.

    1999-01-01

    We present an extension for the 2D (zonal mean) version of our Numerical Spectral Mode (NSM) that incorporates Hines' Doppler spread parameterization (DSP) for small scale gravity waves (GW). This model is applied to describe the seasonal variations and the semi-annual and quasi-biennial oscillations (SAO and QBO). Our earlier model reproduced the salient features of the mean zonal circulation in the middle atmosphere, including the QBO extension into the upper mesosphere inferred from UARS measurements. In the present model we incorporate also tropospheric heating to reproduce the upwelling at equatorial latitudes associated with the Brewer-Dobson circulation that affects significantly the dynamics of the stratosphere as Dunkerton had pointed out. Upward vertical winds increase the period of the QBO observed from the ground. To compensate for that, one needs to increase the eddy diffusivity and the GW momentum flux, bringing the latter closer to values recommended in the DSP. The QBO period in the model is 30 months (mo), which is conducive to synchronize this oscillation with the seasonal cycle of solar forcing. Multi-year interannual oscillations are generated through wave filtering by the solar driven annual oscillation in the zonal circulation. Quadratic non-linearities generate interseasonal variations to produce a complicated pattern of variability associated with the QBO. The computed temperature amplitudes for the SAO and QBO are in substantial agreement with observations at equatorial and extratropical latitudes. At high latitudes, however, the observed QBO amplitudes are significantly larger, which may be a signature of propagating planetary waves not included in the present model. The assumption of hydrostatic equilibrium not being imposed, we find that the effects from the vertical Coriolis force associated with the equatorial oscillations are large for the vertical winds and significant for the temperature variations even outside the tropics but are

  8. 3-D Structure of the Slave and Rae Cratons Provides Clues to Their Construction

    NASA Astrophysics Data System (ADS)

    Snyder, D. B.

    2013-12-01

    Deep geologic structures within cratons that make up continental cores were long neglected. Recently acquired geophysical data from large observational arrays and geochemical data resulting from exploration for diamond has now made possible co-registration of large-scale (400-km depth), truly 3-dimensional data sets. P-waves, surface waves and magnetotelluric observations provide 3-D wavespeed and conductivity models. Multi-azimuthal receiver functions map seismic discontinuity surfaces in 3-D. Xenolith suites erupted in kimberlites provide rock samples at key lithospheric depths, albeit at sparsely distributed locations. These multi-disciplinary models are becoming available for several key cratons worldwide; here the deep structure of the Slave and Rae cratons of the Canadian Shield is described. Lithospheric layers with tapered, wedge-shaped margins are common. Slave craton layers are sub-horizontal and indicate construction of the craton core at 2.7 Ga by underthrusting and flat stacking of lithosphere. The central Rae craton has predominantly dipping discontinuities that indicate construction at 1.9 Ga by thrusting similar to that observed in crustal ';thick-skinned' fold-and-thrust belts. 3-D mapping of conductivity and metasomatism, the latter via mineral recrystallization and resetting of isotopic ages, overprints primary structures in both cratons. Distribution of more conductivitve mantle suggests that assumed causative pervasive metasomatism occurs at 100-200 km depths with ';chimneys' reaching to shallower depths, typically in locations where kimberlites or mineralization has occurred.

  9. Temperature and compositional variations in the Australian cratons

    NASA Astrophysics Data System (ADS)

    Tesauro, Magdala; Kaban, Mikhail; Aitken, Alan; Kennett, Brian

    2017-04-01

    The upper mantle of the Australian continent has been deeply investigated in the last two decades using a variety of geophysical methods. The resulting models have revealed the robust large-scale features of the continental lithosphere of Australia, i.e., faster seismic velocities in the Archean and Proterozoic cratons in the West, North and South Australia and slower velocities in the eastern Phanerozoic margin. Furthermore, it has been identified a layered velocity structure in central Australia. The zone of low seismic velocities in the uppermost mantle is underlain by the high-velocity zone. This layered structure may have a thermal origin, due to a redistribution of high heat producing elements within the crust or reflect compositional changes, e.g. a presence of amphibole. To discern temperature and compositional variations in the Australian upper mantle, we apply an iterative technique, which employs a joint inversion of the seismic tomography and gravity data. This technique consists in removing the effect of the crust from the observed gravity field and topography. In the second step, the residual mantle gravity field and residual topography are inverted to obtain a 3-D density model of the upper mantle. The inversion technique accounts for the notion that these fields are controlled by the same factors but in a different way (e.g., depending on depth and horizontal dimension of the heterogeneity.) This enables us to locate the position of principal density anomalies in the upper mantle. Afterwards, the thermal contribution to the density structure is estimated by inverting the seismic tomography model AusREM (http://rses.anu.edu.au/seismology/AuSREM/index.php). Based on the residual fields, we construct an initial compositional model of the upper mantle. In particular, a negative residual density anomaly is interpreted as the material having a larger Mg# and depleted in garnet and CPX Then, the initial thermal model is re-estimated with the new

  10. Stalled Orogen Linked to East Antarctic Craton Assembly

    NASA Astrophysics Data System (ADS)

    Martos, Y. M.; Ferraccioli, F.; Finn, C.; Bell, R. E.; Jordan, T. A.; Damaske, D.

    2015-12-01

    The interior of East Antarctica is often regarded as a coherent Archean craton surrounded by Paleo to Neoproterozoic orogenic belts. Here we use recent aerogeophysical, satellite magnetic, satellite gravity and passive seismic results in central East Antarctica to challenge this view. Firstly, anomalously thick crust (compared to most other cratons) has been imaged in East Antarctica by both passive seismic and gravity modelling with values up to 60 km (Ferraccioli et al., 2011, Nature; An et al., 2015, JGR). The thick crust underlies both the Gamburtsev Subglacial Mountains and an elevated region between Lake Vostok and Dronning Maud Land, referred to as the East Antarctic Mountain Ranges plateau (An et al., 2015). Second, satellite magnetic data reveal that the Gamburtev Province lies in between the Ruker/Princess Elizabeth Land, Vostok, Nimrod/South Pole and Recovery provinces. The Nimrod/ South Pole province is a Paleo to Meso Proterozoic igneous province formed along the edges of the Archean/Paleoproterozoic Mawson continent (e.g. Goodge and Fanning, 2010 JGR). Our aerogeophysical and sediment provenance data interpretations suggest that the Gamburtsev Province represents a distinct Grenvillian-age orogenic belt. A stalled orogen with thick crust (i.e. an orogen where widespread orogenic collapse and root delamination has not occurred)- is preserved in the interior of East Antarctica resembling e.g. the Paleoproterozoic Trans Hudson Orogen and segments of Grenvillian orogens in Laurentia. The stalled orogen may relate to widespread accretionary and collisional events within Rodinia. However, passive seismic interpretations (An et al., 2015) favour linking crustal thickening to the Pan-African age assembly of Greater India, East Antarctica and Australia within Gondwana (e.g. Aitken et al., 2014 GRL). Further aerogeophysical observations over Princess Elizabeth Land are timely to enable more robust correlations with geological observations and to help dating the

  11. Potential field analysis images Paleoproterozoic terrane boundaries in the unexposed Northern Gawler Craton, Australia

    NASA Astrophysics Data System (ADS)

    Baines, G.; Giles, D.; Betts, P.; Backé, G.

    2008-12-01

    In areas of limited or zero basement exposure, potential field analysis provides an invaluable tool for determining the architecture continental cratons. We present an example from the Northern Gawler Craton, Australia. Here, the basement rocks are almost completely covered by Neoproterozoic and younger sedimentary rocks (with <<1% basement outcrop), so are amongst the least studied on the Australian continent. However, these rocks should preserve the best record of the Gawler Craton's interactions with neighbouring cratons during the amalgamation of Proterozoic Australia. We focus on the basement architecture in the Marla region of the northernmost Gawler Craton. We use geophysical techniques and apply a top-down approach to penetrate the significant thickness of cover and determine the structure of the unexposed northern Gawler Craton. The architecture, density and magnetic susceptibility of the overlying cover sequences are constrained from the surficial geology, borehole data and seismic reflection profiles. The effect of these cover sequences is then removed from gravity and magnetic data highlighting the basement structure. We then determine the architecture of the basement with depth from the potential field data by combining depth-to-source analyses, with forward and inverse modelling techniques constrained by petrophysical data from drill-holes. Results of this analysis include the observation of a major crustal boundary at the NE-SW trending Middle Bore Fault. To the NW of this boundary, crustal scale sources produce large gravity and magnetic anomalies. Whereas to the SE anomalies are sourced in the upper crust and overlie uniform middle to lower crust. We suggest that the Middle Bore Fault represents a boundary between allochthonous terranes that may have accreted to the Gawler craton during the Kimban Orogeny (~1.7 Ga) and the Archaean Gawler Craton that is overlain by Paleoproterozoic metasediments. The basement structure revealed by this approach

  12. Geophysical imaging of metacratonizaton in the northern edge of the Congo craton in Cameroon

    NASA Astrophysics Data System (ADS)

    Goussi Ngalamo, Jeannot F.; Bisso, D.; Abdelsalam, Mohamed G.; Atekwana, Estella A.; Katumwehe, Andrew B.; Ekodeck, G. E.

    2017-05-01

    We used the World Gravity Map (WGM 2012) data to investigate the Archean Congo craton and the Oubanguides orogenic belt in Cameroon. The Oubanguides orogenic belt constitutes, from northwest to southeast, the Neoproterozoic West Cameroon domain, the Paleoproterozoic-Neoproterozoic Adamawa-Yade domain, and the dominantly Neoproterozoic Yaoundé domain (the crustal expression of the suture zone between the Congo craton and the orogenic terranes). We analyzed the WGM 2012 data to identify different gravity anomalies. We also applied the two-dimensional (2D) radially-averaged power spectral analysis to the WGM 2012 data to estimate the Moho depth. Additionally, we developed a 2D forward gravity model along a Nsbnd S profile to image the lithospheric structure of the Precambrian entities. We found that: (1) the Congo craton, the Yaoundé domain, the southeastern part of the West Cameroon domain, and the northern part of the Adamawa-Yade domain are characterized by low gravity anomaly. (2) the southern part of the Adamawa-Yade domain is marked by a pronounced E-W trending high gravity anomaly. (3) the crust is thicker beneath the Congo craton, the Yaoundé domain and the southern part of the Adamawa-Yade domain. (4) the presence of a denser lower crust material beneath the southern part of the Adamawa-Yade domain. We propose that this denser crustal material is an under-thrusted portion of the Congo craton that has been densified through metacratonization processes that accompanied collision between the craton and the orogenic terranes. This is in good agreement with geological and geochemical observations indicating that the northern edge of the Congo craton and the Adamawa-Yade domain had undergone metacratonization during the Neoproterozoic. Our suggestion is also in good agreement with observations which show that the margins of many cratons worldwide have been decratonized due to subduction processes. Our work highlights the importance of potential field geophysical

  13. The San Francisco Consortium; An Educational Association for Urban Affairs. Progress Report.

    ERIC Educational Resources Information Center

    San Francisco Consortium, CA.

    The San Francisco Consortium was formed in the Fall of 1967 by 5 institutions: City College of San Francisco, Golden Gate College, San Francisco State College, University of California-San Francisco Medical Center and the University of San Francisco. Its primary purpose is to be the instrument through which the resources of the major local…

  14. New aerosol particles formation in the Sao Paulo Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Vela, Angel; Andrade, Maria de Fatima; Ynoue, Rita

    2016-04-01

    The Sao Paulo Metropolitan Area (SPMA), in the southeast region of Brazil, is considered a megalopolis comprised of Sao Paulo city and more 38 municipalities. The air pollutant emissions in the SPMA are related to the burning of the fuels: etanol, gasohol (gasoline with 25% ethanol) and diesel. According to CETESB (2013), the road vehicles contributed up to about 97, 87, and 80% of CO, VOCs and NOx emissions in 2012, respectively, being most of NOx associated to diesel combustion and most of CO and VOCs from gasohol and ethanol combustion. Studies conducted on ambient air pollution in the SPMA have shown that black carbon (BC) explains 21% of mass concentration of PM2.5 compared with 40% of organic carbon (OC), 20% of sulfates, and 12% of soil dust (Andrade et al., 2012). Most of the observed ambient PM2.5 mass concentration usually originates from precursors gases such as sulphur dioxide (SO2), ammonia (NH3), nitrogen oxides (NOx) and VOCs as well as through the physico-chemical processes such as the oxidation of low volatile hydrocarbons transferring to the condensed phase (McMurry et al., 2004). The Weather Research and Forecasting with Chemistry model (WRF-Chem; Grell et al. 2005), configured with three nested grid cells: 75, 15, and 3 km, is used as photochemical modeling to describe the physico-chemical processes leading to evolution of particles number and mass size distribution from a vehicular emission model developed by the IAG-USP laboratory of Atmospheric Processes and based on statistical information of vehicular activity. The spatial and temporal distributions of emissions in the finest grid cell are based on road density products compiled by the OpenStreetMap project and measurements performed inside tunnels in the SPMA, respectively. WRF-Chem simulation with coupled primary aerosol (dust and sea-salt) and biogenic emission modules and aerosol radiative effects turned on is conducted as the baseline simulation (Case_0) to evaluate the model

  15. Radar image San Francisco Bay Area, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The San Francisco Bay Area in California and its surroundings are shown in this radar image from the Shuttle Radar Topography Mission (SRTM). On this image, smooth areas, such as the bay, lakes, roads and airport runways appear dark, while areas with buildings and trees appear bright. Downtown San Francisco is at the center and the city of Oakland is at the right across the San Francisco Bay. Some city areas, such as the South of Market district in San Francisco, appear bright due to the alignment of streets and buildings with respect to the incoming radar beam. Three of the bridges spanning the Bay are seen in this image. The Bay Bridge is in the center and extends from the city of San Francisco to Yerba Buena and Treasure Islands, and from there to Oakland. The Golden Gate Bridge is to the left and extends from San Francisco to Sausalito. The Richmond-San Rafael Bridge is in the upper right and extends from San Rafael to Richmond. Angel Island is the large island east of the Golden Gate Bridge, and lies north of the much smaller Alcatraz Island. The Alameda Naval Air Station is seen just below the Bay Bridge at the center of the image. Two major faults bounding the San Francisco-Oakland urban areas are visible on this image. The San Andreas fault, on the San Francisco peninsula, is seen on the left side of the image. The fault trace is the straight feature filled with linear reservoirs, which appear dark. The Hayward fault is the straight feature on the right side of the image between the urban areas and the hillier terrain to the east.

    This radar image was acquired by just one of SRTM's two antennas and, consequently, does not show topographic data, but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover and urbanization. The overall faint striping pattern in the images is a data processing artifact due to the

  16. San Francisco and Bay Area, CA, USA

    NASA Image and Video Library

    1991-06-14

    STS040-152-100 (5-14 June 1991) --- Although clouds obscure part of the city of San Francisco and the mouth of San Francisco Bay, development and physiographic features in the immediate vicinity of the bay are well displayed. The photograph clearly shows the eastern part of the city, including the Embarcadero, the Bay Bridge, which was damaged in the 1989 earthquake, and Candlestick Park, San Mateo, and Dumbarton Bridges, cross the southern portion of the bay. Vari-colored salt ponds also rim the southern Bay near Moffett Field. Highway 280 runs along the San Andreas fault south of the city. On the eastern margin of the bay are Berkeley the Sacramento River and the Haywood and Calaveras faults.

  17. Radar image San Francisco Bay Area, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The San Francisco Bay Area in California and its surroundings are shown in this radar image from the Shuttle Radar Topography Mission (SRTM). On this image, smooth areas, such as the bay, lakes, roads and airport runways appear dark, while areas with buildings and trees appear bright. Downtown San Francisco is at the center and the city of Oakland is at the right across the San Francisco Bay. Some city areas, such as the South of Market district in San Francisco, appear bright due to the alignment of streets and buildings with respect to the incoming radar beam. Three of the bridges spanning the Bay are seen in this image. The Bay Bridge is in the center and extends from the city of San Francisco to Yerba Buena and Treasure Islands, and from there to Oakland. The Golden Gate Bridge is to the left and extends from San Francisco to Sausalito. The Richmond-San Rafael Bridge is in the upper right and extends from San Rafael to Richmond. Angel Island is the large island east of the Golden Gate Bridge, and lies north of the much smaller Alcatraz Island. The Alameda Naval Air Station is seen just below the Bay Bridge at the center of the image. Two major faults bounding the San Francisco-Oakland urban areas are visible on this image. The San Andreas fault, on the San Francisco peninsula, is seen on the left side of the image. The fault trace is the straight feature filled with linear reservoirs, which appear dark. The Hayward fault is the straight feature on the right side of the image between the urban areas and the hillier terrain to the east.

    This radar image was acquired by just one of SRTM's two antennas and, consequently, does not show topographic data, but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover and urbanization. The overall faint striping pattern in the images is a data processing artifact due to the

  18. San Francisco and Bay Area, CA, USA

    NASA Image and Video Library

    1973-06-22

    SL2-03-118 (June 1973) --- An infrared photograph of the San Francisco Bay, California area, taken from the Skylab 1/2 space station in Earth orbit. THE PICTURE SHOULD BE HELD WITH THE CLOUDS AND PACIFIC OCEAN ON THE LEFT. This photograph was taken by one of the six lenses of the Itek-furnished S190-A Multispectral Photographic Facility Experiment in the Multiple Docking Adapter of the space station. Type 2443 film was used. Note the thickly populated and highly developed area around the bay. Among the cities visible in this photograph are San Francisco, Oakland, Berkeley and San Jose. This view extends eastward to show a portion of the San Joaquin Valley. The S190-A experiment is part of the Skylab Earth Resources Experiment Package (EREP). Photo credit: NASA

  19. Origins of cratonic mantle discontinuities: A view from petrology, geochemistry and thermodynamic models

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Massuyeau, Malcolm; Gaillard, Fabrice

    2017-01-01

    Geophysically detectible mid-lithospheric discontinuities (MLD) and lithosphere-asthenosphere boundaries (LAB) beneath cratons have received much attention over recent years, but a consensus on their origin has not yet emerged. Cratonic lithosphere composition and origin is peculiar due to its ultra-depletion during plume or accretionary tectonics, cool present-day geothermal gradients, compositional and rheological stratification and multiple metasomatic overprints. Bearing this in mind, we integrate current knowledge on the physical properties, chemical composition, mineralogy and fabric of cratonic mantle with experimental and thermodynamic constraints on the formation and migration of melts, both below and within cratonic lithosphere, in order to find petrologically viable explanations for cratonic mantle discontinuities. LABs characterised by strong seismic velocity gradients and increased conductivity require the presence of melts, which can form beneath intact cratonic roots reaching to 200-250 km depth only in exceptionally warm and/or volatile-rich mantle, thus explaining the paucity of seismical LAB observations beneath cratons. When present, pervasive interaction of these - typically carbonated - melts with the deep lithosphere leads to densification and thermochemical erosion, which generates topography at the LAB and results in intermittent seismic LAB signals or conflicting seismic, petrologic and thermal LAB depths. In rare cases (e.g. Tanzanian craton), the tops of live melt percolation fronts may appear as MLDs and, after complete lithosphere rejuvenation, may be sites of future, shallower LABs (e.g. North China craton). Since intact cratons are presently tectonomagmatically quiescent, and since MLDs produce both positive and negative velocity gradients, in some cases with anisotropy, most MLDs may be best explained by accumulations (metasomes) of seismically slow minerals (pyroxenes, phlogopite, amphibole, carbonates) deposited during past

  20. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Although clouds obscure part of the city of San Francisco and the mouth of the Bay (37.5N, 122.0W), many cultural and natural features in the immediate vicinity are obvious. The Bay Bridge which was damaged in the 1989 earthquake, Candlestick Park, San Mateo and Dumbarton Bridges as well as the various colored settling ponds rimming the south end of the Bay, the San Andreas and Calaveras faults and many of the major highways can be seen.

  1. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Although clouds obscure part of the city of San Francisco and the mouth of the Bay (37.5N, 122.0W), many cultural and natural features in the immediate vicinity are obvious. The Bay Bridge which was damaged in the 1989 earthquake, Candlestick Park, San Mateo and Dumbarton Bridges as well as the various colored settling ponds rimming the south end of the Bay, the San Andreas and Calaveras faults and many of the major highways can be seen.

  2. Concept and Use of Psychoactive Drugs Among University Students in the Sao Paulo Area

    ERIC Educational Resources Information Center

    Zanini, Antonio C.; And Others

    1977-01-01

    This paper presents the results of a medical-social questionnaire made by members of the Scientific Commission of the First International Congress of Drug Addiction Among University Students, Sao Paulo, Brazil, 1974. (Author)

  3. Concept and Use of Psychoactive Drugs Among University Students in the Sao Paulo Area

    ERIC Educational Resources Information Center

    Zanini, Antonio C.; And Others

    1977-01-01

    This paper presents the results of a medical-social questionnaire made by members of the Scientific Commission of the First International Congress of Drug Addiction Among University Students, Sao Paulo, Brazil, 1974. (Author)

  4. The SAO/NASA Astrophysics Data System: A Gateway to the Planetary Sciences Literature

    NASA Astrophysics Data System (ADS)

    Henneken, E. A.; Accomazzi, A.; Grant, C. S.; Kurtz, M. J.; Thompson, D.; Bohlen, E.; Murray, S. S.

    2009-03-01

    The SAO/NASA Astrophysics Data System (ADS) provides various free services for finding, accessing, and managing bibliographic data, including a basic search form, the myADS notification service, and private libraries, plus access to scanned published articles.

  5. Vehicular emissions of organic particulate matter in Sao Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Oyama, B. S.; Andrade, M. F.; Herckes, P.; Dusek, U.; Röckmann, T.; Holzinger, R.

    2015-12-01

    Vehicular emissions have a strong impact on air pollution in big cities. Many factors affect these emissions: type of vehicle, type of fuel, cruising velocity, and brake use. This study focused on emissions of organic compounds by Light (LDV) and Heavy (HDV) duty vehicle exhaust. The study was performed in the city of Sao Paulo, Brazil, where vehicles run on different fuels: gasoline with 25 % ethanol (called gasohol), hydrated ethanol, and diesel (with 5 % of biodiesel). The vehicular emissions are an important source of pollutants and the principal contribution to fine particulate matter (smaller than 2.5 μm, PM2.5) in Sao Paulo. The experiments were performed in two tunnels: Janio Quadros (TJQ) where 99 % of the vehicles are LDV, and Rodoanel Mario Covas (TRA) where up to 30 % of the fleet was HDV. The PM2.5 samples were collected on quartz filters in May and July 2011 at TJQ and TRA, respectively, using two samplers operating in parallel. The samples were analyzed by Thermal-Desorption Proton-Transfer-Reaction Mass-Spectrometry (TD-PTR-MS), and by Thermal-Optical Transmittance (TOT). The organic aerosol (OA) desorbed at TD-PTR-MS represented around 30 % of the OA estimated by the TOT method, mainly due to the different desorption temperatures, with a maximum of 870 and 350 °C for TOT and TD-PTR-MS, respectively. Average emission factors (EF) organic aerosol (OA) and organic carbon (OC) were calculated for HDV and LDV fleet. We found that HDV emitted more OA and OC than LDV, and that OC emissions represented 36 and 43 % of total PM2.5 emissions from LDV and HDV, respectively. More than 700 ions were identified by TD-PTR-MS and the EF profiles obtained from HDV and LDV exhibited distinct features. Nitrogen-containing compounds measured in the desorbed material up to 350 °C contributed around 20 % to the EF values for both types of vehicles, possibly associated with incomplete fuel burning. Additionally, 70 % of the organic compounds measured from the aerosol

  6. Seismic Tomography of Central Sao Miguel, Azores Islands (Portugal)

    NASA Astrophysics Data System (ADS)

    Almendros, J.; Zandomeneghi, D.; Saccorotti, G.; Barclay, A.; Ibáñez, J. M.

    2005-12-01

    The Azores Archipelago consists of nine volcanic islands, located at about 38° N and 28°W, in the triple junction of the American, Eurasian and African plates. The largest island is Sao Miguel. It has rift zones mainly trending NW-SE and E-W; calderas, as Fogo and Furnas, at the intersection of these tectonic lineaments; and thermal springs and fumaroles distributed along these fault systems. Furnas, Sete Cidades and Fogo are the most active volcanic complexes: central volcanoes with a dominantly trachytic production. Furnas is the youngest and consists of a steep-sided caldera structure formed during several collapses. The most important thermal features lie on an E-W lineament which cuts the Furnas caldera complex. The Fogo volcanic edifice is built over an older submarine lava basement and composed by lava flows, domes and pyroclastic flows deposits, with the summit truncated by a caldera.Thermal manifestations are associated with a NW-SE fault system and consist mainly of fumarolic activity. São Miguel was selected as a site for a seismic experiment in a European Union-sponsored project with the aim of quantifying the seismicity of various quiescent volcanoes in inhabited areas.The 3D distribution of P- and S-wave velocities is derived for central São Miguel, by traveltime tomography. We use P- and S-wave arrival times of 289 local earthquakes by a network of 23 seismometers. The model has good resolution in the shallowest 5 km. There are several Vp anomalies, referred to a composite picture of geologic deposits, volcanic structures and tectonic features. Furnas caldera has a shallow, low Vp value probably marking volcaniclastic sediments. A negative Vp anomaly is associated with the geothermal field of Ribeira Grande. Another low Vp area is related to the highly fractured NW-SE tectonic lineament connecting two geothermal areas in central São Miguel. Conversely, high velocity zones mark a central seismogenetic zone at 4-5 km of depth and the Altiprado

  7. Plume tectonics and cratons formation in the early Earth

    NASA Astrophysics Data System (ADS)

    Gerya, T.; Stern, R. J.; Baes, M.; Fischer, R.; Sizova, E.; Sobolev, S. V.; Whattam, S. A.

    2015-12-01

    Modern geodynamics and continental growth are critically driven by subduction and plate tectonics, however how this tectonic regime started and what geodynamic regime was before remains controversial. Most present-day subduction initiation mechanisms require acting plate forces and/or pre-existing zones of lithospheric weakness, which are themselves the consequence of plate tectonics. Here, we focus on plume-lithosphere interactions and spontaneous plume-induced subduction initiation, which does not require pre-existing lithospheric fabric and is viable for both stagnant lid and mobile/deformable lid conditions. We present results of 2D and 3D numerical modeling of plume-induced deformation and associated crustal growth resulting from tectono-magmatic interaction of ascending mantle plumes with oceanic-type lithosphere. We demonstrate that weakening of the lithosphere by plume-induced magmatism is the key factor allowing for its internal deformation and differentiation resulting in continental crust growth. We also show that plume-lithosphere interaction can enable subduction and rudimentary plate tectonics initiation at the margins of a crustal plateau growing above the plume head. We argue that frequent plume-arc interactions recorded in Archean crust could reflect either short-term plume-induced subduction or plume-induced episodic lithospheric drips. We furthermore suggest a distinct plume-tectonics regime operated on Earth before plate tectonics, which was associated with widespread tectono-magmatic heat and mass exchange between the crust and the mantle. This regime was characterized by weak deformable plates with low topography, massive juvenile crust production from mantle derived melts, mantle-flows-driven crustal deformation, magma-assisted crustal convection and widespread development of lithospheric delamination and crustal drips. Plume tectonics also resulted in growth of hot depleted chemically buoyant subcrustal proto-cratonic mantle layer. Later

  8. A Sharp Edge of the Cratonic Lithosphere of North America

    NASA Astrophysics Data System (ADS)

    Harper, T. B.; Skryzalin, P. A.; Menke, W. H.; Levin, V. L.; Darbyshire, F. A.

    2015-12-01

    Using teleseismic travel time delays, we develop a tomographic model of the lithosphere beneath northeastern North America, from the shore of James Bay in Quebec to the Atlantic coast of New England and to a depth of 300 km. Three major terranes lie within this cratonic margin: the 2.7 Ga Superior province, the 1 Ga Grenville orogenic belt and the 0.3-0.4 Ga Appalachian terranes, which are bounded by the Grenville Front (GF) and Appalachian Front (AF), respectively. Additionally, the 0.8 Ga Avalon terrain was accreted to coastal New England by strike-skip faulting during the Appalachian orogeny. Our tomographic model uses earthquake seismograms recorded by permanent US and Canadian stations, the Transportable Array and the temporary QMIII deployment. All data were corrected for instrument response and record sections were examined visually to identify gross errors in response and timing. Differential arrival times of P and PKP waves were determined by cross-correlation and have a maximum amplitude of about ±1 second. In our model, lithospheric boundaries do not correlate well with geological boundaries, nor do they strike parallel to them. The seismically-fast (by 5% relative to AK135) cratonic lithosphere of North America is much thicker than that of the younger terranes, extending to 200 km or more depth but with a sharp east-dipping eastern edge located (at Moho depths) 100-250 km northwest of the GF. The lithosphere beneath the Grenville and Appalachian terranes, which were affected by subduction during the Grenville and Appalachian orogenies, is slower (by 4%). A sliver of seismically-fast lithosphere, extending to ~150 km depth, occurs along the Atlantic coast and is interpreted as the Avalonian lithosphere.

  9. Laboratory derived constraints on electrical conductivity beneath Slave craton

    NASA Astrophysics Data System (ADS)

    Bagdassarov, Nikolai S.; Kopylova, Maya G.; Eichert, Sandrine

    2007-04-01

    The depth profile of the electrical conductivity, σ(d), beneath the Central Slave craton (Canada) has been reconstructed with the help of laboratory measurements carried out on peridotite xenoliths. σ(T) of xenoliths was determined in the piston-cylinder apparatus at 1 and 2 GPa and from 600 to 1150 °C. σ(T) of xenoliths follows the Arrhenius dependence with the activation energy, E, varying from 2.10 to 1.44 eV depending on temperature range and the Mg-number. The calculated xenolith geotherm and the suggested lithology beneath the Central Slave have been used to constrain σ(d) as follows: σ(d) in the crust varies between 0.5×10-5 and 10-3 S/m; the lithospheric σ(d) sharply decreases below the Moho at 39.4 km to 0.5×10-8 S/m, which corresponds to 460 °C, and then gradually increases with the depth d to 0.5×10-2 S/m. The modeled MT-response of the constrained σ(d) profile has been compared with MT-observations [Jones, A.G., Lezaeta, P., Ferguson, I.J., Chave, A.D., Evans, R.L., Garcia, X., Spratt J., 2003. The electrical structure of the Slave craton. Lithos, 71, 505-527]. The general trend of the calculated MT-response based on the σ(d) model mimics the MT-inversion of the field data from the Central Slave.

  10. An overview of San Francisco Bay PORTS

    USGS Publications Warehouse

    Cheng, Ralph T.; McKinnie, David; English, Chad; Smith, Richard E.

    1998-01-01

    The Physical Oceanographic Real-Time System (PORTS) provides observations of tides, tidal currents, and meteorological conditions in real-time. The San Francisco Bay PORTS (SFPORTS) is a decision support system to facilitate safe and efficient maritime commerce. In addition to real-time observations, SFPORTS includes a nowcast numerical model forming a San Francisco Bay marine nowcast system. SFPORTS data and nowcast numerical model results are made available to users through the World Wide Web (WWW). A brief overview of SFPORTS is presented, from the data flow originated at instrument sensors to final results delivered to end users on the WWW. A user-friendly interface for SFPORTS has been designed and implemented. Appropriate field data analysis, nowcast procedures, design and generation of graphics for WWW display of field data and nowcast results are presented and discussed. Furthermore, SFPORTS is designed to support hazardous materials spill prevention and response, and to serve as resources to scientists studying the health of San Francisco Bay ecosystem. The success (or failure) of the SFPORTS to serve the intended user community is determined by the effectiveness of the user interface.

  11. Morphological evolution in the San Francisco Bight

    USGS Publications Warehouse

    Hanes, Daniel M.; Barnard, Patrick L.

    2007-01-01

    San Francisco Bight, located near the coast of San Francisco, USA, is an extremely dynamic tidal inlet environmental subject to large waves and strong currents. Wave heights coming from the Pacific Ocean commonly exceed 5 m during winter storms. During peak flow tidal currents approach 3 m/s at the Golden Gate, a 1 km wide entrance that connects San Francisco Bay to the Pacific Ocean. Flow structure in this region varies markedly spatially and temporally due to the complex interaction by wind, waves and tidal currents. A multibeam sonar survey was recently completed that mapped in high resolution, for the first time, the bottom morphology in the region of the ebb tidal delta. This data set includes a giant sand wave field covering an area of approximately 4 square kilometers. The new survey enables the calculation of seabed change that has occurred in the past 50 years, since the last comprehensive survey of the area was completed. This comparison indicates an average erosion of 60 centimeters which equates to a total volume change of approximately 9.3 x 107 m3. Morphologic change also indicates that flood channels have filled and that the entire ebb delta is contracting radially.

  12. Observations of gravity waves from satellite and implications for the wave driving of the SAO

    NASA Astrophysics Data System (ADS)

    Ern, Manfred; Preusse, Peter; Riese, Martin

    2015-04-01

    The dynamics at low latitudes in the stratosphere and lower mesosphere is governed by an interplay of the quasi-biennial oscillation (QBO) and the semiannual oscillation (SAO) of the zonal wind. It is known that tropical dynamics has significant influence on the atmosphere over a large range of altitudes and latitudes. For example, QBO and SAO effects are seen in the MLT region, and there is a significant influence of the QBO on surface weather and climate in the Northern Hemisphere during winter. Still, global models have large difficulties in simulating a realistic QBO and SAO. One main uncertainty is the wave driving of these oscillations, in particular the driving by gravity waves (GWs). We derive GW temperature variances, GW momentum fluxes and potential GW drag from over three years of High Resolution Dynamics Limb Sounder (HIRDLS) satellite data in the stratopause region. These observations are compared with the SAO driving due to planetary waves, as well as the zonal wind tendencies, both determined from the ECMWF ERA-Interim (ERAI) reanalysis. HIRDLS satellite observations and ERAI support the general assumption that, due to selective filtering of the GW spectrum by the QBO in the stratosphere, GWs mainly contribute to the SAO momentum budget during SAO eastward wind shear. However, during SAO westward wind shear the GW contribution is usually smaller, and the wave driving is dominated by planetary waves, probably of extratropical origin. Still, we find indications in both satellite observations and ERAI that sometimes GW drag is important also during SAO westward wind shear.

  13. Histological characterization of bone marrow in ectopic bone, induced by devitalized Saos-2 human osteosarcoma cells.

    PubMed

    Nahar, Niru N; Tague, Sarah E; Wang, Jinxi; Danley, Marsha; Garimella, Rama; Anderson, H Clarke

    2013-01-01

    Devitalized Saos-2, cultured human osteosarcoma cells, or guanidinium-hydrochloride (GuHCl) extracts of these cells, induce ectopic bone and marrow formation when implanted subcutaneously in Nu/Nu mice. The aim of the present study was to characterize the bone marrow induced by Saos-2 cell extracts, specifically to determine which of the four major hematopoietic cell lineages: erythropoietic, granulopoietic, lymphopoietic and megakaryocytic, are induced by Saos-2 cell derivatives. Immunohistochemical localization of specific antigens was used to determine the presence of each major cell type (glycophorin A for erythropoietic, neutrophil elastase for granulopoietic, factor-VIII related antigen for megakaryocytes, and CD79a for B lymphocytes). Standard H & E stains confirmed the presence of normally organized apparently complete bone marrow within all newly induced bone at 3 weeks post-implantation of devitalized Saos-2 cells. Immunohistochemistry confirmed the presence of erythropoietic cells, granulopoietic cells, megakaryocytes and B lymphocytes in the ectopic marrow. Saos-2 cells (freeze-dried) or their extracts, implanted subcutaneously into Nu/Nu mice, can induce normal marrow that is host-derived, and contains all major hematopoietic cell lineages. Saos-2 induced marrow could potentially restore deficient marrow and promote bone repair.

  14. Histological characterization of bone marrow in ectopic bone, induced by devitalized Saos-2 human osteosarcoma cells

    PubMed Central

    Nahar, Niru N; Tague, Sarah E; Wang, Jinxi; Danley, Marsha; Garimella, Rama; Anderson, H Clarke

    2013-01-01

    Devitalized Saos-2, cultured human osteosarcoma cells, or guanidinium-hydrochloride (GuHCl) extracts of these cells, induce ectopic bone and marrow formation when implanted subcutaneously in Nu/Nu mice. The aim of the present study was to characterize the bone marrow induced by Saos-2 cell extracts, specifically to determine which of the four major hematopoietic cell lineages: erythropoietic, granulopoietic, lymphopoietic and megakaryocytic, are induced by Saos-2 cell derivatives. Methods: Immunohistochemical localization of specific antigens was used to determine the presence of each major cell type (glycophorin A for erythropoietic, neutrophil elastase for granulopoietic, factor-VIII related antigen for megakaryocytes, and CD79a for B lymphocytes). Results: Standard H & E stains confirmed the presence of normally organized apparently complete bone marrow within all newly induced bone at 3 weeks post-implantation of devitalized Saos-2 cells. Immunohistochemistry confirmed the presence of erythropoietic cells, granulopoietic cells, megakaryocytes and B lymphocytes in the ectopic marrow. Conclusion: Saos-2 cells (freeze-dried) or their extracts, implanted subcutaneously into Nu/Nu mice, can induce normal marrow that is host-derived, and contains all major hematopoietic cell lineages. Clinical Significance: Saos-2 induced marrow could potentially restore deficient marrow and promote bone repair. PMID:23386915

  15. Silencing of NUF2 inhibits proliferation of human osteosarcoma Saos-2 cells.

    PubMed

    Fu, H-L; Shao, L

    2016-01-01

    NUF2 (NUF2, Ndc80 kinetochore complex component), which is essential for kinetochore-microtubule attachment in mitosis, has emerged as a critical mediator of the cell cycle in multiple tumour occurrences. In the present study, we aimed to investigate the role of NUF2 in osteosarcoma, one of the most common primary bone tumours in children and young adults. Lentivirus-mediated short-hairpin RNA (shRNA) targeting NUF2 (Lv-shNUF2) was employed for evaluation in human osteosarcoma Saos-2 cells. After NUF2 silencing, the proliferation of Saos-2 cells was significantly inhibited, as determined by the MTT assay. The colony forming ability was also significantly decreased in Saos-2 cells infected with Lv-shNUF2. Flow cytometry revealed that downregulation of NUF2 in Saos-2 cells caused a remarkable accumulation of the cell population in the S phase. Furthermore, the expression levels of cell cycle regulators cyclin A and cyclin-dependent kinase 2 (CDK2) were notably decreased, whereas those of cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1, were increased in response to NUF2 knockdown in Saos-2 cells. Our findings suggest that NUF2 might modulate cell proliferation via cell cycle control in Saos-2 cells. Downregulation of NUF2 by shRNA might be a novel strategy for early treatment of osteosarcoma using molecular-targeting therapy.

  16. City of San Francisco, California street tree resource analysis

    Treesearch

    E.G. McPherson; J.R. Simpson; P.J. Peper; Q. Xiao

    2004-01-01

    Street trees in San Francisco are comprised of two distinct populations, those managed by the city’s Department of Public Works (DPW) and those managed by private property owners with or without the help of San Francisco’s urban forestry nonprofit, Friends of the Urban Forest (FUF). These two entities believe that the public’s investment in stewardship of San Francisco...

  17. Deaths among homeless persons--San Francisco, 1985-1990.

    PubMed

    1991-12-20

    In San Francisco (1990 population: 723,959), an estimated 6000-18,000 persons are homeless. To characterize the causes of death among homeless persons in San Francisco during 1985-1990, the Health Care for the Homeless Program, San Francisco Department of Public Health, reviewed records of homeless decedents from the city medical examiner's (ME's) office. This report summarizes the results of that study.

  18. Space Radar Image of San Francisco, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of San Francisco, California, taken on October 3,1994. The image is about 40 kilometers by 55 kilometers (25 miles by 34 miles) with north toward the upper right. Downtown San Francisco is visible in the center of the image with the city of Oakland east (to the right) across San Francisco Bay. Also visible in the image is the Golden Gate Bridge (left center) and the Bay Bridge connecting San Francisco and Oakland. North of the Bay Bridge is Treasure Island. Alcatraz Island appears as a small dot northwest of Treasure Island. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on orbit 56. The image is centered at 37 degrees north latitude, 122degrees west longitude. This single-frequency SIR-C image was obtained by the L-band (24 cm) radar channel, horizontally transmitted and received. Portions of the Pacific Ocean visible in this image appear very dark as do other smooth surfaces such as airport runways. Suburban areas, with the low-density housing and tree-lined streets that are typical of San Francisco, appear as lighter gray. Areas with high-rise buildings, such as those seen in the downtown areas, appear in very bright white, showing a higher density of housing and streets which run parallel to the radar flight track. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: the L-band (24 cm), C-band (6 cm) and X-band (3cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes

  19. Implementing Technology for Science Classrooms in Sao Tome and Principe

    NASA Astrophysics Data System (ADS)

    Jardim, Maria Dolores Rodrigues

    This qualitative bounded case study was designed to understand how technology integration in schools could be addressed in a first-wave country. The integration of educational technology in Sao Tome and Principe (STP), a first-wave agricultural civilization, can narrow the divide between STP and third-wave information age societies. The conceptual framework was based on theories of change, learning, and context. Toffler's wave theory described how societies changed while Fullan's change theory examined how the people might change. Roger's diffusion of innovations addressed how processes change. Bandura, Vygotsky, and Siemen provided the framework for the learning within the model of change. Finally, the context theories of Tessmer and Richey's instructional design, Lave and Wenger's situated learning, and Sticht's functional context theory were applied. Twenty five individuals from 5 schools, including teachers, school directors, key educational stakeholders, and the minister of education were involved in a pilot project to integrate technology into the science curriculum. The data were collected via interviews, reflective summaries, and confidential narratives. The resulting data were analyzed to find emerging patterns. The results of this analysis showed that a first-wave civilization can adopt a third-wave civilization's features in terms of technology integration, when there is the support of opinion leaders and most of the necessary contextual requirements are in place. The study contributes to social change by providing access to knowledge through technology integration, which empowers both teachers and students.

  20. G-protein Stimulatory α Subunit Is Involved in Osteogenic Activity in Osteoblastic Cell Line SaOS-2 Cells

    PubMed Central

    Yamazaki, Miwa; Suzuki, Akira; Ozono, Keiichi; Michigami, Toshimi

    2006-01-01

    In an attempt to study the roles of G-protein stimulatory subunit α (Gsα) in osteoblasts, we introduced an expression vector encoding Gsα into human osteoblastic cell line SaOS-2, and established the clones stably overexpressing Gsα (SaOS-2-Gsα). In SaOS-2-Gsα, the intracellular content of cyclic AMP (cAMP) was increased compared with the parental SaOS-2 cells. In addition, when treated with PTH[1-34], SaOS-2-Gsα exhibited more accumulation of intracellular cAMP compared with the parental cells, suggesting an increased responsiveness to PTH. We evaluated the proliferation rates of SaOS-2-Gsα and the parental SaOS-2 cells, and found that the proliferation was accelerated in SaOS-2-Gsα cells. Reverse transcription-polymerase chain reaction (RT-PCR) analyses exhibited the increased expression of Runx2, a transcription factor involved in osteoblast differentiation, in SaOS-2-Gsα cells. Finally, to examine the osteoblastic function in vivo, we inoculated SaOS-2-Gsα or parental SaOS-2 cells subcutaneously to immunocompromised nude mice. Although tumors in nude mice were not formed after inoculation of parental SaOS-2 cells, SaOS-2-Gsα cells proliferated in host animals leading to the formation of tumors with mineralized bone-like tissues. Taken together, these results suggest that the signals via Gsα play critical roles in the proliferation and osteogenic functions of osteoblasts. PMID:24790323

  1. G-protein Stimulatory α Subunit Is Involved in Osteogenic Activity in Osteoblastic Cell Line SaOS-2 Cells.

    PubMed

    Yamazaki, Miwa; Suzuki, Akira; Ozono, Keiichi; Michigami, Toshimi

    2006-01-01

    In an attempt to study the roles of G-protein stimulatory subunit α (Gsα) in osteoblasts, we introduced an expression vector encoding Gsα into human osteoblastic cell line SaOS-2, and established the clones stably overexpressing Gsα (SaOS-2-Gsα). In SaOS-2-Gsα, the intracellular content of cyclic AMP (cAMP) was increased compared with the parental SaOS-2 cells. In addition, when treated with PTH[1-34], SaOS-2-Gsα exhibited more accumulation of intracellular cAMP compared with the parental cells, suggesting an increased responsiveness to PTH. We evaluated the proliferation rates of SaOS-2-Gsα and the parental SaOS-2 cells, and found that the proliferation was accelerated in SaOS-2-Gsα cells. Reverse transcription-polymerase chain reaction (RT-PCR) analyses exhibited the increased expression of Runx2, a transcription factor involved in osteoblast differentiation, in SaOS-2-Gsα cells. Finally, to examine the osteoblastic function in vivo, we inoculated SaOS-2-Gsα or parental SaOS-2 cells subcutaneously to immunocompromised nude mice. Although tumors in nude mice were not formed after inoculation of parental SaOS-2 cells, SaOS-2-Gsα cells proliferated in host animals leading to the formation of tumors with mineralized bone-like tissues. Taken together, these results suggest that the signals via Gsα play critical roles in the proliferation and osteogenic functions of osteoblasts.

  2. 76 FR 81371 - Safety Zone; San Francisco New Year's Eve Fireworks Display, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-28

    ...The Coast Guard will enforce the safety zone for the annual San Francisco New Year's Eve Fireworks Display in the Captain of the Port, San Francisco area of responsibility during the dates and times noted below. This action is necessary to protect life and property of the maritime public from the hazards associated with the fireworks display. During the enforcement period, unauthorized persons or vessels are prohibited from entering into, transiting through, or anchoring in the safety zone, unless authorized by the Patrol Commander (PATCOM).

  3. ASTER Images San Francisco Bay Area

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image of the San Francisco Bay region was acquired on March 3, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters about 50 to 300 feet ), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    Image: This image covers an area 60 kilometers (37 miles) wide and 75 kilometers (47 miles) long in three bands of the reflected visible and infrared wavelength region. The combination of bands portrays vegetation in red, and urban areas in gray. Sediment in the Suisun Bay, San Pablo Bay, San Francisco Bay, and the Pacific Ocean shows up as lighter shades of blue. Along the west coast of the San Francisco Peninsula, strong surf can be seen as a white fringe along the shoreline. A powerful rip tide is visible extending westward from Daly City into the Pacific Ocean. In the lower right corner, the wetlands of the South San Francisco Bay National Wildlife Refuge appear as large dark blue and brown polygons. The high spatial resolution of ASTER allows fine detail to be observed in the scene. The main bridges of the area (San Mateo, San Francisco-Oakland Bay, Golden Gate, Richmond-San Rafael, Benicia-Martinez, and Carquinez) are easily picked out, connecting the different communities in the Bay area. Shadows of the towers along the Bay Bridge can be seen over the adjacent bay water. With enlargement the entire road network can be easily mapped; individual buildings are visible, including the shadows of the high-rises in downtown San Francisco.

    Inset: This enlargement of the San Francisco Airport highlights the high spatial resolution of ASTER. With further enlargement and careful examination, airplanes can be seen at the terminals.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth

  4. ASTER Images San Francisco Bay Area

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image of the San Francisco Bay region was acquired on March 3, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters about 50 to 300 feet ), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    Image: This image covers an area 60 kilometers (37 miles) wide and 75 kilometers (47 miles) long in three bands of the reflected visible and infrared wavelength region. The combination of bands portrays vegetation in red, and urban areas in gray. Sediment in the Suisun Bay, San Pablo Bay, San Francisco Bay, and the Pacific Ocean shows up as lighter shades of blue. Along the west coast of the San Francisco Peninsula, strong surf can be seen as a white fringe along the shoreline. A powerful rip tide is visible extending westward from Daly City into the Pacific Ocean. In the lower right corner, the wetlands of the South San Francisco Bay National Wildlife Refuge appear as large dark blue and brown polygons. The high spatial resolution of ASTER allows fine detail to be observed in the scene. The main bridges of the area (San Mateo, San Francisco-Oakland Bay, Golden Gate, Richmond-San Rafael, Benicia-Martinez, and Carquinez) are easily picked out, connecting the different communities in the Bay area. Shadows of the towers along the Bay Bridge can be seen over the adjacent bay water. With enlargement the entire road network can be easily mapped; individual buildings are visible, including the shadows of the high-rises in downtown San Francisco.

    Inset: This enlargement of the San Francisco Airport highlights the high spatial resolution of ASTER. With further enlargement and careful examination, airplanes can be seen at the terminals.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth

  5. Plume-induced dynamic instabilities near cratonic blocks: Implications for P-T-t paths and metallogeny

    NASA Astrophysics Data System (ADS)

    Guillou-Frottier, L.; Burov, E.; Cloetingh, S.; Le Goff, E.; Deschamps, Y.; Huet, B.; Bouchot, V.

    2012-06-01

    Plume head-lithosphere interactions around cratonic blocks result in thermo-mechanical disturbances that lead to heating and burial phases of crustal rocks. We present results from numerical models of plume head-cratonic blocks interactions where a free upper surface condition and realistic rheologies are accounted for. These models include distinct cratonic blocks embedded within a continental lithosphere and separated by several hundreds of kilometers. Surface topography, thermal field and effective viscosity values are tracked for 20 Myr of interactions. The modeled dynamic interaction of a plume head around cratonic blocks results in two main types of instabilities, each of them resulting in a distinct P-T-t path. The "slab-like" instability, focused on cratonic edges when plume head is away from the craton center, shows a near-isothermal burial phase, while the "drip-like" instability occurring above plume head material results in a near-isobaric heating phase. Consequently, both clockwise and counterclockwise P-T-t paths can be expected around cratons, as actually observed around the Tanzanian craton and other cratonic areas. Metallogenic data from gemstone-bearing rocks in south-east Africa and data from ultrahigh temperature and ultrahigh pressure metamorphism are compatible with our model. It appears that vertical mantle dynamics around cratons may also explain thermobarometric signatures that are often attributed to horizontal tectonics.

  6. 78 FR 54487 - YP Western Directory LLC, San Francisco Division, Publishing Operations Group, YP Subsidiary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-04

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF LABOR Employment and Training Administration YP Western Directory LLC, San Francisco Division, Publishing... Zero Chaos, San Francisco, California; YP Western Directory LLC, San Francisco Division, Publishing...

  7. 1. Historic American Buildings Survey San Francisco CallBulletin Library VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey San Francisco Call-Bulletin Library VIEW OF FACADE Demolished August 1940 - St. Rose's Church, North Brannan & Fifth Streets, San Francisco, San Francisco County, CA

  8. 1. Historic American Buildings Survey DeYoung Museum, San Francisco RUSSIAN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Historic American Buildings Survey DeYoung Museum, San Francisco RUSSIAN HILL HOUSES (Photo taken in Middle 1850's) - Captain Dakin House, Taylor & Vallejo Streets, San Francisco, San Francisco County, CA

  9. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. 165.1187 Section 165.1187... Limited Access Areas Eleventh Coast Guard District § 165.1187 Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. (a) Location. All waters extending...

  10. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. 165.1187 Section 165.1187... Limited Access Areas Eleventh Coast Guard District § 165.1187 Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. (a) Location. All waters extending...

  11. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. 165.1187 Section 165.1187... Limited Access Areas Eleventh Coast Guard District § 165.1187 Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. (a) Location. All waters extending...

  12. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. 165.1187 Section 165.1187... Limited Access Areas Eleventh Coast Guard District § 165.1187 Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. (a) Location. All waters extending...

  13. 33 CFR 165.1187 - Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. 165.1187 Section 165.1187... Limited Access Areas Eleventh Coast Guard District § 165.1187 Security Zones; Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, San Francisco Bay, California. (a) Location. All waters extending...

  14. 33 CFR 334.1065 - U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California; restricted area. 334.1065 Section 334.1065... Island, San Francisco Bay, California; restricted area. (a) The area. San Francisco Bay on the east...

  15. 33 CFR 334.1065 - U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California; restricted area. 334.1065 Section 334.1065... Island, San Francisco Bay, California; restricted area. (a) The area. San Francisco Bay on the east...

  16. 33 CFR 334.1065 - U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California; restricted area. 334.1065 Section 334.1065... Island, San Francisco Bay, California; restricted area. (a) The area. San Francisco Bay on the east...

  17. 33 CFR 334.1065 - U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California; restricted area. 334.1065 Section 334.1065... Island, San Francisco Bay, California; restricted area. (a) The area. San Francisco Bay on the east...

  18. 33 CFR 334.1065 - U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false U.S. Coast Guard Station, San Francisco Bay, Yerba Buena Island, San Francisco Bay, California; restricted area. 334.1065 Section 334.1065... Island, San Francisco Bay, California; restricted area. (a) The area. San Francisco Bay on the east...

  19. English Articulation between the San Francisco Unified School District and the City College of San Francisco. Youth Data Archive Issue Brief

    ERIC Educational Resources Information Center

    Gurantz, Oded

    2012-01-01

    San Francisco's Bridge to Success (BtS) initiative brings together the City and County of San Francisco, the San Francisco Unified School District (SFUSD), the City College of San Francisco (CCSF), and key community organizations to promote postsecondary success for underrepresented students. Various working groups, each comprised of staff from…

  20. On the relations between cratonic lithosphere thickness, plate motions, and basal drag

    USGS Publications Warehouse

    Artemieva, I.M.; Mooney, W.D.

    2002-01-01

    An overview of seismic, thermal, and petrological evidence on the structure of Precambrian lithosphere suggests that its local maximum thickness is highly variable (140-350 km), with a bimodal distribution for Archean cratons (200-220 km and 300-350 km). We discuss the origin of such large differences in lithospheric thickness, and propose that the lithospheric base can have large depth variations over short distances. The topography of Bryce Canyon (western USA) is proposed as an inverted analog of the base of the lithosphere. The horizontal and vertical dimensions of Archean cratons are strongly correlated: larger cratons have thicker lithosphere. Analysis of the bimodal distribution of lithospheric thickness in Archean cratons shows that the "critical" surface area for cratons to have thick (>300 km) keels is >6-8 ?? 106 km2 . Extrapolation of the linear trend between Archean lithospheric thickness and cratonic area to zero area yields a thickness of 180 km. This implies that the reworking of Archean crust should be accompanied by thinning and reworking of the entire lithospheric column to a thickness of 180 km in accord with thickness estimates for Proterozoic lithosphere. Likewise, extrapolation of the same trend to the size equal to the total area of all Archean cratons implies that the lithospheric thickness of a hypothesized early Archean supercontinent could have been 350-450 km decreasing to 280-400 km for Gondwanaland. We evaluate the basal drag model as a possible mechanism that may thin the cratonic lithosphere. Inverse correlations are found between lithospheric thickness and (a) fractional subduction length and (b) the effective ridge length. In agreement with theoretical predictions, lithospheric thickness of Archean keels is proportional to the square root of the ratio of the craton length (along the direction of plate motion) to the plate velocity. Large cratons with thick keels and low plate velocities are less eroded by basal drag than small

  1. Crustal and upper mantle structure of the Slave craton from P- and S- Receiver Functions

    NASA Astrophysics Data System (ADS)

    Barantseva, Olga; Vinnik, Lev; Artemieva, Irina

    2017-04-01

    Teleseismic events recorded by POLARIS array in NW Canada (Slave craton) and Yellowknife station were used to calculate a sufficient number of receiver functions for P (PRF) and S (SRF) waves. Velocity (Vp and Vs) and Vp/Vs profiles from the Earth's surface down to 300 km are obtained through the simultaneous inversion of PRF and SRF with teleseismic travel time residuals for the crust and upper mantle. We observe highly heterogeneous structure of the cratonic upper mantle. The Lehman discontinuity (the bottom of the low velocity zone) is found in the western Slave craton, whereas it is not observed in the eastern part of the Slave craton. At stations located in the southern part of the craton, we observe an increase of S-wave velocities (as compared to IASP91 values) at the depths 45-150 km which is typical for depleted cratonic mantle. Low Vp/Vs ratio, obtained for the uppermost mantle (1.65-1.70) can be explained by a high fraction of Opx. A comparison of our results with available xenoliths data shows a good agreement between seismic velocity change at a depth of ca. 160 km and a decrease in mantle depletion at about the same depth.

  2. The meaning of midlithospheric discontinuities: A case study in the northern U.S. craton

    NASA Astrophysics Data System (ADS)

    Hopper, Emily; Fischer, Karen M.

    2015-12-01

    Converted wave imaging has revealed significant negative velocity gradients, often termed midlithospheric discontinuities, within the thick, high-velocity mantle beneath cratons. In this study, we investigate the origins and implications of these structures with high-resolution imaging of mantle discontinuities beneath the Archean Wyoming, Superior and Medicine Hat, and Proterozoic Yavapai and Trans-Hudson terranes. Sp phases from 872 temporary and permanent broadband stations, including the EarthScope Transportable Array, were migrated into three-dimensional common conversion point stacks. Four classes of discontinuities were observed. (1) A widespread, near-flat negative velocity gradient occurs largely at 70-90 km depth beneath both Archean and Proterozoic cratons. This structure is consistent with the top of a frozen-in layer of volatile-rich melt. (2) Dipping negative velocity gradients are observed between 85 and 200 km depth. The clearest examples occur at the suture zones between accreted Paleoproterozoic Yavapai arc terranes and the Wyoming and Superior cratons. These interfaces could represent remnant subducting slabs, and together with eclogite in xenoliths, indicate that subduction-related processes likely contributed to cratonic mantle growth. (3) Sporadic positive velocity gradients exist near the base of the lithospheric mantle, perhaps due to laterally variable compositional layering. (4) In contrast to off-craton regions, clear Sp phases are typically not seen at lithosphere-asthenosphere boundary depths beneath Archean and Proterozoic terranes, consistent with a purely thermal contrast between cratonic mantle lithosphere and asthenosphere.

  3. On the relations between cratonic lithosphere thickness, plate motions, and basal drag

    NASA Astrophysics Data System (ADS)

    Artemieva, I.; Artemieva, I.; Mooney, W. D.

    2001-12-01

    Seismic and thermal estimates suggest a highly variable thickness of Precambrian lithosphere (140-350 km), with a bimodal distribution for Archean cratons ( ~ 220 km and ~ 350 km). We discuss the origin of such large variations in lithospheric thickness and examine mechanisms of lithospheric erosion. Our analysis shows that the horizontal and vertical dimensions of Archean cratons are strongly correlated: larger cratons have thicker lithosphere. The basal drag model of lithosphere erosion (Sleep, 2001) is tested as a means of explaining the present-day bimodal distribution of lithospheric thicknesses of the Archean cratons. In agreement with theoretical predictions, we find that lithospheric thickness in Archean keels is proportional to the square root of the ratio of the craton length (along the direction of plate motion) to the plate velocity. These results show that the basal drag model provides a viable explanation for the variation in thickness of Archean cratonic roots. Basal drag may have varied in magnitude over the past 4 Ga. Higher mantle temperatures in the Archean would have resulted in lower mantle viscosity. This in turn would have reduced basal drag and basal erosion, and promoted the preservation of thick (>300 km) Archean keels, even if plate velocities were high during the Archean.

  4. Paleoproterozoic postcollisional magmatic belt of the southern Siberian craton

    NASA Astrophysics Data System (ADS)

    Salnikova, E. B.; Larin, A. M.; Kotov, A. B.; Levitsky, V. I.; Reznitsky, L. Z.; Kovach, V. P.; Yakovleva, S. Z.

    2003-04-01

    Paleoproterozoic time is characterized by large-scale collisional and postcollisional magmatic activity evidenced in the most of ancient cratons. This global event is related to the Arctic supercontinent assemblage (Rogers, 1996). The formation of postcollisional magmatic belt at 1.9-1.8 Ga within the south-west flanking of the Siberian craton is a remarkable example of these processes happened during overall lithospheric convergence. This belt is extends for about 3000 km from the southern Enisey ridge at the west to the central Aldan shield at the east. Within the central Aldan shield the latest collisional event occurred 1925+/-5 Ma (Kotov et al, 2003) and post-collisional subalkaline S- and I-type granites emplaced at 1916+/-10 Ma (Bibikova et al., 1989), 1901+/-1 Ma (Frost et al., 1998) and 1899+/-6 Ma (Kotov et al, 2003). However at the southern Olekma terrain (western Aldan shield) the syncollisional granites have formed at 1906+/-4 Ma and postcollisional Kodar granitoids were generated at 1876-1873 Ma (Larin et al., 2000). The is a tendency outlined in timing of postcollision processes to the west (in modern coordinates). Ages of postcollisional Kevakta granitoid plutons (1846+/-8 Ma) and volcanics of North-Baikal volcano-plutonic belt (1869+/-6 Ma 1856+/-3 Ma), Baikal folded area, support this tendency. Emplacement of the Primorsky complex postcollisional rapakivi-type granitoids (southern Baikal lake) occurred at 1859+/-16 Ma (Donskaya et al., 2002). New results of U-Pb single zircon and baddeleyite dating demonstrate that formation of late-synkinematic syenite, charnockite and pegmatitic veins (1856±12 Ma, 1853±20 Ma) and calciphyre (1868±2 Ma) within the eastern part of the Sharyzhalgay block (southern Baikal lake) occurred virtually within the same episode. Postcollisional intrusive charnockite of the Shumikha complex from the western Sharyzhalgay block dated at 1861±1 Ma (Donskaya et al., 2001) and 1871±17 Ma (Levitsky et al., 2002). Subalcaline

  5. 77 FR 37604 - Safety Zone; Fourth of July Fireworks, City of San Francisco, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-22

    ... SECURITY Coast Guard 33 CFR Part 165 Safety Zone; Fourth of July Fireworks, City of San Francisco, San... Guard will enforce the safety zone for the City of Sausalito's Fourth of July Fireworks in the Captain... Sausalito's Fourth of July Fireworks Display in 33 CFR 165.1191. This safety zone will be in effect from 9 a...

  6. 77 FR 70891 - Safety Zone; Bay Bridge Construction, San Francisco Bay, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-28

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Bay Bridge Construction, San Francisco Bay..., CA in support of the Bay Bridge Construction Safety Zone from November 1, 2012 through July 31, 2013... process would be completed. Because of the dangers posed by over-head construction of the Bay Bridge, the...

  7. 78 FR 34123 - Notice of Inventory Completion: San Francisco State University NAGPRA Program, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-06

    ... from site CA-PLA-9 in Placer County, CA. This notice is published as part of the National Park Service... site CA-PLA-9 in Placer County, CA, by San Francisco State University personnel in conjunction with... point. The age of site CA-PLA-9 is unknown, but the site is located within the historically documented...

  8. Heterogeneously hydrated mantle beneath the late Archean Yilgarn Craton

    NASA Astrophysics Data System (ADS)

    Ivanic, T. J.; Nebel, O.; Jourdan, F.; Faure, K.; Kirkland, C. L.; Belousova, E. A.

    2015-12-01

    Archean mafic-ultramafic melts, crystallized as layered intrusions in the upper crust and extruded as komatiitic flows, are primary probes of upper mantle chemistry. However, the message from their primary chemical composition can be compromised by different modes of contamination. Contaminants are typically cryptic in terms of their geochemical and isotopic signals but may be related to metasomatised mantle sources, ambient crustal assimilation or subduction-related inputs. In this work we present critical evidence for both dry and wet Archean mantle sources for two juxtaposed layered intrusions in the Australian Yilgarn Craton. The ca. 2813 Ma Windimurra and ca. 2800 Ma Narndee Igneous Complexes in Western Australia are two adjacent layered intrusions and would be expected to derive via similar mantle sections. A key difference in their chemistry is the presence of crystal-bound water in the Narndee Igneous Complex, represented primarily by abundant hornblende. Such a primary hydrous phase is notably absent in the Windimurra Igneous Complex. New 40Ar/39Ar plateau ages for fresh Narndee hornblende (weighted mean: 2805 ± 14 Ma, MSWD = 1.8, probability = 0.18) agrees with the published U-Pb age of 2800 ± 6 Ma for the complex and is consistent with a magmatic origin for this phase. Zircon Hf and whole-rock Hf and Nd isotopes for the Narndee Igneous Complex indicate only minor crustal contamination, in agreement with H and O isotope values in amphibole and O isotope values in rare zircon crystals, plagioclase and pyroxene within both complexes. These findings illustrate a fast temporal transition, in proximal bodies, from anhydrous to hydrous mantle sources with very minor crustal contamination. These large layered mafic-ultramafic intrusions are igneous bodies with a primitive chemical bulk composition that requires large degrees of mantle melting. This has been attributed by many workers to mantle plume activity, yet not without dispute, as subduction-related flux

  9. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Although clouds obscure part of the city of San Francisco and the mouth of the Bay (37.5N, 122.0W), many cultural and natural features in the immediate vicinity are obvious. The Bay Bridge which was damaged in the 1989 earthquake, Candlestick Park, San Mateo and Dumbarton Bridges as well as the various colored settling ponds rimming the south end of the Bay, the San Andreas and Calaveras faults and many of the major highways can be seen. Color infrared photography is very useful for haze penetration and greater definition of the imagery as well as vegetation detection, depicted as shades of red.

  10. Ancient tropical climates warm San Francisco gathering

    SciTech Connect

    Kerr, R.A.

    1994-01-14

    Climate records preserved in the Greenland ice sheet got a lot of the attention at the fall meeting of the American Geophysical Union (AGU) in San Francisco last month, but ancient tropical records were a rival attraction. In talks scattered in unrelated sessions, researchers reported a possible role for the tropics in driving the last ice age, a link between high latitudes and the tropics that may have redirected human evolution, and a tropical climate periodicity that may fill a gap in the understanding of climate variability.

  11. Legionellosis--the 1980 San Francisco outbreak.

    PubMed

    Conwill, D E; Werner, S B; Dritz, S K; Bissett, M; Coffey, E; Nygaard, G; Bradford, L; Morrison, F R; Knight, M W

    1982-10-01

    During the first half of March 1980, an unseasonal outbreak of legionellosis, which involved at least 14 of approximately 1,000 workers, occurred in a 6-month-old office building in San Francisco. An epidemiologic investigation revealed that persons 50 yr of age and older were at increased risk of disease. The outbreak was temporally associated with operation of the building's air conditioning system. In addition, Legionella pneumophila Serogroups 1, 4, and 6 were identified in water samples taken from a rooftop air conditioning cooling tower located directly across the street from an area of recent excavation.

  12. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Although clouds obscure part of the city of San Francisco and the mouth of the Bay (37.5N, 122.0W), many cultural and natural features in the immediate vicinity are obvious. The Bay Bridge which was damaged in the 1989 earthquake, Candlestick Park, San Mateo and Dumbarton Bridges as well as the various colored settling ponds rimming the south end of the Bay, the San Andreas and Calaveras faults and many of the major highways can be seen. Color infrared photography is very useful for haze penetration and greater definition of the imagery as well as vegetation detection, depicted as shades of red.

  13. Towards a Holistic Model for the Tectonic Evolution of the North China Craton

    NASA Astrophysics Data System (ADS)

    Kusky, T. M.; Polat, A.; Windley, B. F.; Wang, J.; Deng, H.

    2016-12-01

    The North China Craton (NCC) consists of distinctly different tectonic elements assembled during the late Archean - early Proterozoic. We propose a new tectonic evolution of the NCC. The Eastern Block (EB) consists of small microblocks that resemble a collage of accreted arc-rocks from a sutured archipelago similar to the SW Pacific, accreted between 2.6 and 2.7 Ga. An Atlantic-type margin developed on the western side of the EB by 2.5 Ga, and a >1,300 km long arc/accretionary prism collided with this passive margin at 2.5 Ga, obducting ophiolites and ophiolitic mélanges, and forming a foreland basin. This was followed by arc-polarity reversal, and injection of mantle wedge-derived melts. By 2.43 Ga, the ocean behind the accreted arc closed through the collision of an oceanic plateau. Rifting of the amalgamated craton followed at 2.4-2.35 Ga, with a failed rift arm preserved in the center of the craton, and two that successfully made an ocean along the northern margin. By 2.3 Ga an arc built on older cratonic material collided with this passive margin which soon converted to an Andean-type margin. Andean margin tectonics affected much of the craton from 2.3-1.9 Ga, forming a broad E-W swath of continental margin magmas, and retro-arc sedimentary basins including a superimposed basin over the passive margin on the northern margin. From 1.88-1.79 Ga the craton experienced a craton-wide granulite facies metamorphism and basement reactivation event with high-pressure granulites and eclogites in the north, and medium-pressure granulites across the craton. Early Proterozoic granulites and anatectic melts were generated by high-grade metamorphism and partial melting at mid-crustal levels beneath a collisionally-thickened plateau. This collision of the NCC on its northern margin was with the Columbia (Nuna) Continent. The NCC broke out in the period 1753-1673 Ma, as indicated by the formation of a suite of anorthosite, mangerite, charnockite, and alkali-feldspar granites

  14. Lithospheric Structure of the North American Craton Imaged Using Waveform Inversion of Global and Usarray Data

    NASA Astrophysics Data System (ADS)

    Schaeffer, A. J.; Lebedev, S.

    2014-12-01

    The North American Craton, now forming the stable core of North America, has a long, eventful tectonic history. The assembly of the craton, collisions and accretion at its current boundaries, major rifting episodes within it, and the loss of ancient lithosphere beneath parts of it are type examples of these key components of cratonic dynamics and evolution. Seismic tomography offers rich evidence on the structure and evolution of the cratonic lithosphere. With the deployment of the USArray during the last decade, much of the North American continent has been densely sampled with broadband seismic data. The resolution of regional-scale imaging, however, remains uneven, with important questions regarding deep structure, lateral extent and evolution difficult to answer. Here we present a new high-resolution model of the upper mantle beneath North America constrained by waveform fits of over 700,000 vertical-component broadband seismograms. Automated multimode waveform inversion was used to extract structural information from surface and S waveforms, yielding resolving power from the crust down to the transition zone, and improved resolution for a variety of features in North America. The internal structure of the Craton is resolved in detail. The lithosphere surrounding the 1 Ga failed Mid-Continental Rift shows reduced wavespeeds compared to the surrounding craton, likely indicating thermo-chemical alteration of the sub-continental lithospheric mantle. The sharp northern boundaries of the cratonic lithosphere closely follow the coastlines, with North America's and Greenland's lithospheric roots clearly separated. Strong lateral velocity gradients at depth observed in western Canada indicate the transition from cratonic lithosphere to Cordillera closely follows the surface trace of the Deformation Front. On the eastern margin of the continent, where multiple episodes of continental rifting are superimposed, the craton boundary coincides with the western extent of the

  15. 8. Photocopy of drawing (from California Historical Society, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. Photocopy of drawing (from California Historical Society, San Francisco, California, Sherman, artist, before 1846) GENERAL VIEW OF MISSION (RIGHT), BARRACKS (TO LEFT OF MISSION) & GENERAL VALLEJO RESIDENCE (CENTER, WITH TOWER) - Mission San Francisco Solano de Sonoma, First & Spain Streets, Sonoma, Sonoma County, CA

  16. Book Buddies. Volunteers Bring Stories to San Francisco's Hospitalized Children.

    ERIC Educational Resources Information Center

    Schneider, Marcia

    This report describes Book Buddies, a volunteer-based outreach project of the San Francisco Public Library, whose goal is to provide reading services and to promote reading aloud to children and their families in San Francisco hospitals and pediatric clinics. The introduction chronicles the need for such a program; offers background information on…

  17. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  18. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  19. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  20. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  1. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  2. Forest conditions in the San Francisco Mountains Forest Reserve, Arizona

    Treesearch

    John B. Leiberg; Theodore F. Rixon; Arthur. Dodwell

    1904-01-01

    On April 12, 1902, President Roosevelt issued a proclamation "for the purpose of consolidating into one reserve the lands heretofore embraced in the San Francisco Mountains Forest Reserves and of including therein the other adjacent lands within the description herein after given." The consolidated area is now known as the San Francisco Mountains Forest...

  3. Lithopsheric anisotropy in the Archean Slave craton, Canada

    NASA Astrophysics Data System (ADS)

    Snyder, D. B.; Bostock, M.; Lockhart, G. D.

    2003-12-01

    Shear wave anisotropy and discontinuity studies of teleseismic earthquakes recorded at single seismic stations help to define vertical mantle stratigraphic columns. Beneath the Archean outcrops of the central Slave craton seismic discontinuities at 38, 115, 140, and 190 km appear to bound two distinct anisotropic layers. The discontinuity at 38 km is the Moho; discontinuities at 110-120 and 140-150 km depths observed at multiple nearby stations indicate that a layer of low velocity or distinct anisotropy exists between these depths. The coherent pulses at about 13 seconds on the radial component indicates a strong decrease in velocity at 110 km depth north and west of the Ekati diamond mine, but not to the south. The response on the transverse component indicates a rotation of anisotropic fabric at 117 km depth, a reversal at 140 km, and another rotation at 190 km. A flip in polarity at a back azimuth of about 280° occurs in the 117 km discontinuity and apparently marks an axis of symmetry of anisotropy, here probably the dip direction of steep layering or planar fabric. SKS anisotropy studies at this station indicate that the upper of two anisotopic layers has a fast-axis direction of 010° . Geochemical studies of xenolith samples from nearby kimberlites suggest that the boundaries at 115 and 140 bound a layer of ultra-depleted harzburgite, almost pure olivine, that formed as oceanic crust.

  4. Architecture of the Sulu crustal suture between the North China Craton and Yangtze Craton: Constraints from Mesozoic granitoids

    NASA Astrophysics Data System (ADS)

    Zhao, Rui; Wang, Qingfei; Liu, Xuefei; Wang, Wei; Pan, Ruiguang

    2016-12-01

    The Yangtze Craton (YC) and the North China Craton (NCC) collided in the Triassic, producing the prominent NNE-trending Sulu high-ultrahigh pressure metamorphic belt and associated crustal thickening. Late Jurassic-Early Cretaceous granitic plutons in the Sulu orogenic belt and the Jiaobei terrane to the west were used to investigate the crustal architecture across the suture. Our new data show that the granitoids from these two regions have similar chemical and isotope compositions. They are all characterized by very high Sr and low Y-Yb contents, high Sr/Y and (La/Yb)N ratios, similar ƐNd(t) values from - 18.2 to - 21.4, and similar initial 87Sr/86Sr ratios from 0.7076 to 0.7119. The calculated Nd two-stage model ages (TDM2) based on whole rock data vary from 2415 to 2662 Ma. Co-magmatic zircon crystals from the granitoids have variably negative ƐHf(t) values from - 26.8 to - 12.8, with the calculated Hf TDM2 from 2008 to 2892 Ma. The inherited zircon crystals from these rocks are dominated by Neoproterozoic (800-600 Ma) and Triassic-Early Jurassic ( 220 Ma and 180 Ma) ages. The ƐHf(t) values of the inherited zircon crystals with U-Pb ages between 180 Ma and 800 Ma from Sulu and Jiaobei range from - 21.6 to 4.2 and from - 23 to - 1.9, respectively. They all plot within the field of crustal evolution between 1385 and 2583 Ma. The similar whole rock geochemical signatures and similar inherited zircon data indicate a similar source for the granitoids in these two regions. We propose that the source regions across the suture all belong to the YC. The occurrence of the YC crust beneath the NCC at this location is thought to have resulted from the westward subduction of the YC beneath the NCC and subsequent continental collision in the Triassic. In this model, the abundant 800 to 230 Ma inherited zircon crystals in the granitoids are interpreted to have been derived from the source region whereas the rare older inherited zircon crystals are thought to have been

  5. The effect of deproteinized bovine bone mineral on saos-2 cell proliferation.

    PubMed

    Khojasteh, Arash; Ghahremani, Mohammad Hossein; Ostad, Seyed Nasser; Eslami, Mohammad; Motahhary, Pourya; Morad, Golnaz; Shidfar, Shireen

    2013-01-01

    Deproteinized bovine bone mineral (Bio-Oss) is a xenogenic bone substitute, widely used in maxillofacial bone regeneration. The aim of this in vitro study was to investigate its influence on the growth behavior of human osteosarcoma cell line, Saos-2 culture, and compare it with the physiologic dose of Dexamethasone, an inductive factor for osteoblasts. Human osteosarcoma cells, Saos-2, were cultured on Bio-Oss and their growth rate was compared to Saos-2 cultures treated with Dexamethasone 10(-7) M in contrast to cells cultivated in PBS, in the control group. Assessment of proliferation was performed after 24, 36, and 48 hours by counting cells using trypan blue exclusion method. Alkaline phosphatase was measured spectrophotometrically at 405 nm with paranitrophenol buffer. After 48 hours, the number of Saos-2 cells increased significantly when subcultured with Bio-Oss. Bio-Oss was more effective on the enhancement of proliferation of Saos-2 cells when compared to the physiologic dose of Dexamethasone (P<0.05). Alkaline phosphatase activity increased in cells grown on Bio-Oss and dexamethasone 10(-7) M in contrast to cells cultivated in PBS control group. The greatest level of activity was observed in the group containing Bio-Oss after 48 hour. The significant increase of cell proliferation and alkaline phosphatase activity in cells cultured on Bio-Oss, compared to Dexamethasone-treated cells, suggests the important role of this bone substitute in promoting bone regeneration.

  6. Spatial distribution of eclogite in the Slave cratonic mantle: The role of subduction

    NASA Astrophysics Data System (ADS)

    Kopylova, Maya G.; Beausoleil, Yvette; Goncharov, Alexey; Burgess, Jennifer; Strand, Pamela

    2016-03-01

    We reconstructed the spatial distribution of eclogites in the cratonic mantle based on thermobarometry for ~ 240 xenoliths in 4 kimberlite pipes from different parts of the Slave craton (Canada). The accuracy of depth estimates is ensured by the use of a recently calibrated thermometer, projection of temperatures onto well-constrained local peridotitic geotherms, petrological screening for unrealistic temperature estimates, and internal consistency of all data. The depth estimates are based on new data on mineral chemistry and petrography of 148 eclogite xenoliths from the Jericho and Muskox kimberlites of the northern Slave craton and previously reported analyses of 95 eclogites from Diavik and Ekati kimberlites (Central Slave). The majority of Northern Slave eclogites of the crustal, subduction origin occurs at 110-170 km, shallower than in the majority of the Central Slave crustal eclogites (120-210 km). The identical geochronological history of these eclogite populations and the absence of steep suture boundaries between the central and northern Slave craton suggest the lateral continuity of the mantle layer relatively rich in eclogites. We explain the distribution of eclogites by partial preservation of an imbricated and plastically dispersed oceanic slab formed by easterly dipping Proterozoic subduction. The depths of eclogite localization do not correlate with geophysically mapped discontinuities. The base of the depleted lithosphere of the Slave craton constrained by thermobarometry of peridotite xenoliths coincides with the base of the thickened lithospheric slab, which supports contribution of the recycled oceanic lithosphere to formation of the cratonic root. Its architecture may have been protected by circum-cratonic subduction and shielding of the shallow Archean lithosphere from the destructive asthenospheric metasomatism.

  7. Giant Mesozoic gold provinces related to the destruction of the North China craton

    NASA Astrophysics Data System (ADS)

    Li, Jian-Wei; Bi, Shi-Jian; Selby, David; Chen, Lei; Vasconcelos, Paulo; Thiede, David; Zhou, Mei-Fu; Zhao, Xin-Fu; Li, Zhan-Ke; Qiu, Hua-Ning

    2012-10-01

    Lode gold deposits in Precambrian cratons represent the world's major gold source and were mostly generated during formation and stabilization of the cratons. However, there is an extraordinary exception in the North China craton (NCC), where lode gold deposits formed after prolonged stabilization of the craton. Molybdenite Re-Os and hydrothermal sericite and biotite 40Ar/39Ar dating of major gold deposits from the Xiaoqinling district, southern NCC, bracket their emplacement in the range of 154.1±1.1 to 118.9±1.2 Ma (n=23), postdating formation of the craton by more than 1.7 billion years. Fluid inclusions extracted from gold-bearing pyrite have elevated 3He/4He ratios (1.52-0.22 Ra) and mantle-like Ne isotopes (20Ne/22Ne=10.02-9.22 and 21Ne/22Ne=0.033-0.027), indicating presence of mantle-derived fluids in the ore system. Measured δ34S of pyrite and δD and δ18O of hydrothermal micas and fluid inclusion waters in auriferous quartz further confirm a magmatic/mantle source for sulfur and ore fluids. Gold deposits of similar ages also widely occur in the eastern and northern margins of the NCC, which, together with those in the Xiaoqinling district, have a total reserve of ˜2500 t gold, forming the only known giant late Mesozoic gold province in the world's Precambrian cratons. These deposits formed coevally with extensive felsic to mafic magmatism, development of intracontinental rift basins, and exhumation of metamorphic core complexes across the eastern NCC, events interpreted as indicating thinning and destruction of the lithosphere beneath the craton. Rising of asthenosphere coupled with destruction of the lithosphere has generated voluminous mafic and felsic magmas that provided sufficient fluids, sulfur and, by inference, other ore components to form the giant gold provinces.

  8. Episodic, Multi-staged Lithospheric Delamination Responsible for Destruction of the North China Craton

    NASA Astrophysics Data System (ADS)

    Huang, J.; Wang, Y.; Zhong, S.

    2013-12-01

    Archean cratons represent the oldest tectonic units on the Earth and most of them are tectonically stable for >3 Ga. The North China Craton (NCC), however, had undergone extensive destruction during the Mesozoic to Cenozoic as seen from surface volcanism, magmatism, and tectonic deformation and geochemical and seismic observations suggesting removal and replacement of thick, old, and fertile cratonic lithosphere with thin, young, and depleted oceanic-type lithosphere [Griffin et al., 1998; Xu, 2001; Menzies et al., 2007; Zhu et al., 2012; Zhang et al., 2012]. Lithospheric delamination has been proposed to explain different episodes of volcanism in the Jurassic [Gao et al., 2004; 2008] and Cretaceous [Yang et al., 2003; Wu et al., 2003] on NCC and hence as a mechanism for destruction of NCC. However, the relatively long period (~100 Myr) of volcanism associated with the destruction of NCC was considered as a challenge to the delamination process [Menzies et al., 2007] which typically lasts for several Myr [Conrad and Molnar, 1999]. Here we show that delamination for cratonic lithosphere with chemically buoyant root and non-Newtonian rheology, different from that for normal lithosphere that was considered in most previous geodynamic studies, is episodic and multi-staged and may last for tens to 100 Myrs. For cratonic lithosphere with non-Newtonian rheology with relatively large chemical buoyancy, the cold, shallow part of the lithosphere goes unstable first, causing significant stirring and mixing of asthenospheric mantle and cratonic lithosphere. This delamination process may explain the main geochemical signatures in the Jurassic and Cretaceous volcanic rocks found in the NCC including their eclogite component [Gao et al., 2004, 2008] and sourcing both cratonic lithosphere and asthenosphere [Zheng et al., 2000]. Subduction process, by increasing tectonic stress and water content, helps reduce the lithospheric viscosity sufficiently to delaminate the entire

  9. Seismic anisotropy of Precambrian lithosphere: Insights from Rayleigh wave tomography of the eastern Superior Craton

    NASA Astrophysics Data System (ADS)

    Petrescu, Laura; Darbyshire, Fiona; Bastow, Ian; Totten, Eoghan; Gilligan, Amy

    2017-05-01

    The thick, seismically fast lithospheric keels underlying continental cores (cratons) are thought to have formed in the Precambrian and resisted subsequent tectonic destruction. A consensus is emerging from a variety of disciplines that keels are vertically stratified, but the processes that led to their development remain uncertain. Eastern Canada is a natural laboratory to study Precambrian lithospheric formation and evolution. It comprises the largest Archean craton in the world, the Superior Craton, surrounded by multiple Proterozoic orogenic belts. To investigate its lithospheric structure, we construct a frequency-dependent anisotropic seismic model of the region using Rayleigh waves from teleseismic earthquakes recorded at broadband seismic stations across eastern Canada. The joint interpretation of phase velocity heterogeneity and azimuthal anisotropy patterns reveals a seismically fast and anisotropically complex Superior Craton. The upper lithosphere records fossilized Archean tectonic deformation: anisotropic patterns align with the orientation of the main tectonic boundaries at periods ≤110 s. This implies that cratonic blocks were strong enough to sustain plate-scale deformation during collision at 2.5 Ga. Cratonic lithosphere with fossil anisotropy partially extends beneath adjacent Proterozoic belts. At periods sensitive to the lower lithosphere, we detect fast, more homogenous, and weakly anisotropic material, documenting postassembly lithospheric growth, possibly in a slow or stagnant convection regime. A heterogeneous, anisotropic transitional zone may also be present at the base of the keel. The detection of multiple lithospheric fabrics at different periods with distinct tectonic origins supports growing evidence that cratonization processes may be episodic and are not exclusively an Archean phenomenon.

  10. 33 CFR 165.T11-630 - Safety zone; Giants Enterprises Fireworks Display, San Francisco Bay, San Francisco, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Safety zone; Giants Enterprises Fireworks Display, San Francisco Bay, San Francisco, CA. 165.T11-630 Section 165.T11-630 Navigation and... Areas Eleventh Coast Guard District § 165.T11-630 Safety zone; Giants Enterprises Fireworks Display, San...

  11. Crustal structure of the late-Archean to Proterozoic Glenburgh Terrane in the Western Australian Craton: roles of a micro-continent in craton formation and reworking

    NASA Astrophysics Data System (ADS)

    Yuan, H.; Johnson, S.; Dentith, M. C.; Murdie, R.; Gessner, K.; Korhonen, F. J.; Bodin, T.

    2016-12-01

    The Capricorn Orogen records the Paleoproterozoic amalgamation of the Archean Pilbara and Yilgarn cratons to form the Western Australian Craton. Regional surveys involving geological mapping, geochemistry, and geophysics have revealed a prolonged tectonic history in craton assembly and subsequent intracratonic reworking, which have significantly re-shaped the orogenic crust. Augmenting the recent geophysical efforts to characterize the crustal architecture, a high-density passive-source seismic study has targeted the Glenburgh Terrane, an exotic late-Archean to Paleoproterozoic crustal element which differs structurally and isotopically from the surrounding Archean units. New seismic results show prominent signals of the Moho and intracrustal discontinuities, replicating the overall trend and depth range in the previous high-resolution deep crustal reflection image. The Terrane is imaged as a distinct felsic block which is consistent with a small Vp/Vs ratio ( 1.70) and a slow velocity mid- to lower crust. Available magnetotelluric measurements also indicate a resistive shallow and middle crust. At the margins the crust is thickened with a fast velocity lower crust, and changes to more intermediate to mafic composition, which may be related to paleo-subduction and terrane collision that initiated the assembly of the Western Australian Craton. These results confirm that the Glenburgh Terrane is a compositionally distinct micro continent formed in the Archean. Isotope studies have shown that significant post-cratonization magmatism differentiated the crust, which may account for the slow velocity mid-crust and fast shallow crustal layer that correlate with the voluminous granite batholiths in the region. Our results illustrate that multi-disciplinary datasets bring complementary resolution and therefore may put tighter constraints on the tectonic processes that have affected the crust.

  12. Optical properties of rare earth doped strontium aluminate (SAO) phosphors: A review

    NASA Astrophysics Data System (ADS)

    Kshatri, D. S.; Khare, A.

    2014-11-01

    After the first news on rare earth (RE) doped strontium aluminate (SAO) phosphors in late 1990s, researchers all over the world geared up to develop stable and efficient persistent phosphors. Scientists studied various features of long lasting phosphors (LLP) and tried to earmark appropriate mechanism. However, about two decades after the discovery of SrAl2O4: Eu2+, Dy3+, the number of persistent luminescent materials is not significant. In this review, we present an overview of the optical characteristics of RE doped SAO phosphors in terms of photoluminescence (PL), thermoluminescence (TL) and afterglow spectra. Also, we refresh the work undertaken to study diverse factors like dopant concentration, temperature, surface energy, role of activator, etc. Simultaneously, some of our important findings on SAO are reported and discussed in the end.

  13. High Water Contents in the Siberian Cratonic Mantle: An FTIR Study of Udachnaya Peridotite Xenoliths

    NASA Technical Reports Server (NTRS)

    Doucet, Luc S.; Peslier, Anne H.; Ionov, Dimitri A.; Brandon, Alan D.; Golovin, Alexander V.; Ashchepkov, Igor V.

    2013-01-01

    Water is believed to be a key factor controlling the long-term stability of cratonic lithosphere, but mechanisms responsible for the water content distribution in the mantle remain poorly constrained. Water contents were obtained by FTIR in olivine, pyroxene and garnet for 20 well-characterized peridotite xenoliths from the Udachnaya kimberlite (central Siberian craton) and equilibrated at 2-7 GPa. Water contents in minerals do not appear to be related to interaction with the host kimberlite. Diffusion modeling indicates that the core of olivines preserved their original water contents. The Udachnaya peridotites show a broad range of water contents in olivine (6.5 +/- 1.1 to 323 +- 65 ppm H2O (2 sigma)), and garnet (0 - 23 +/- 6 ppm H2O). The water contents of olivine and garnet are positively correlated with modal clinopyroxene, garnet and FeO in olivine. Water-rich garnets are also rich in middle rare earth elements. This is interpreted as the result of interaction between residual peridotites and water rich-melts, consistent with modal and cryptic metasomatism evidenced in the Siberian cratonic mantle. The most water-rich Udachnaya minerals contain 2 to 3 times more water than those from the Kaapvaal craton, the only craton with an intact mantle root for which water data is available. The highest water contents in olivine and orthopyroxene in this study (>= 300 ppm) are found at the bottom of the lithosphere (> 6.5 GPa). This is in contrast with the Kaapvaal craton where the olivines of peridotites equilibrated at > 6.4 GPa have < 1 ppm H2O. The latter "dry" olivine may make the base of the Kaapvaal cratonic root strong and thus protects it from erosion by the convective mantle The calculated viscosity for water-rich Udachnaya peridotites at > 6 GPa is lower or similar (8.4× 10(exp 16) to 8.0× 10(exp 18) Pa./s) to that of the asthenosphere (<= 3.7x10(exp 18) Pa./s ). Such lithologies would not be able to resist delamination by the convecting asthenosphere

  14. The Preservation of Meso- Archean Refractory Lithospheric Mantle Underneath the Eastern Margin of the Tanzania Craton

    NASA Astrophysics Data System (ADS)

    Shu, Q.; Liu, J.; Pearson, G. D.; Gibson, S. A.

    2014-12-01

    Numerous studies on the petrology and geochemistry of peridotite xenoliths from the Tanzanian Craton and its rifted margins have investigated the origin, chemical change and thermal state of the cratonic roots from its core area (Nzega and Mwadui), its Northern (Marsabit) and Eastern margin Labait and Lashaine area (e.g. Dawson, 1964; Henjes-Kunst and Altherr, 1991; Lee & Rudnick, 1999; Chesley et al., 1999; Gibson et al., 2013). These studies suggest that the Tanzanian cratonic mantle formed via high degrees of melt extraction in the Archean (oldest Re-depletion age TRD = 3.4 Ga, Burton et al., 2000) and sev­eral episodes of refertilization. In order to gain further temporal and chemical understanding on the effects of tectonic processes on cratonic roots, we carried out a Re-Os isotopic study on peridotites (n = 11) from Lashaine, which will be followed by Lu-Hf, Sm-Nd and Sr isotope investigations of the constituent minerals of the same samples. The preliminary whole-rock Os isotope data from Lashaine peridotites show a large range of 187Os/188Os (0.1061 - 0.1261), with TRD ages from Meso-Archean to very young (3.1 Ga to 0.3 Ga). There is a negative correlation between TRD and bulk alumina contents. One sample with the lowest Al2O3 yields the oldest age of 3.1 Ga. Five samples range from 2.5 to 2.8 Ga, three give ages close to 2 Ga, and one sample with a high Al2O3 has a TRD at 0.3 Ga. The positive Al2O3-187Os/188Os correlation trend passes above the PM composition may reflect ancient metasomatism by high Re/Os melts or recent metasomatism by very radiogenic Os plume-derived melts. These processes could be related to the evolution of the peripheral Proterozoic mobile belts, or Cenozoic rifting on the Eastern margin. Collectively, our new Os isotope data demonstrate that Meso-Archean (at least 3.1 Ga old) mantle portions are still retained underneath the rifted Eastern margin of the Craton. This is in line with previous results indicating that Archean cratonic

  15. Genistein modulates the effects of parathyroid hormone in human osteoblastic SaOS-2 cells.

    PubMed

    Chen, Wen-Fang; Wong, Man-Sau

    2006-06-01

    Genistein and parathyroid hormone (PTH) are anabolic agents that stimulate bone formation through their direct actions in osteoblastic cells. In the present study, we aimed to determine whether genistein modulates the actions of PTH in human osteoblastic SaOS-2 cells in an oestrogen-depleted condition. The present results showed that genistein (10(-8) to 10(-6) m) induced alkaline phosphatase (ALP) activity and osteoprotegrin (OPG) expression in SaOS-2 cells in a dose-dependent manner. These effects could be completely abolished by co-treatment with oestrogen antagonist ICI 182780 (7alpha-[9-[(4,4,5,5,5-pentafluoropentyl)sulfonyl]nonyl]-estra-1,3,5(10)-triene-3,17beta-diol). Genistein (at 1 microM) could stimulate the mRNA expression of receptor activator of NF-kappaB ligand (RANKL). As OPG and RANKL are known to modulate osteoclastogenesis, the ability of genistein to modulate OPG and RANKL expression in SaOS-2 cells suggested that it might modulate osteoclastogenesis through its direct actions on osteoblastic cells. PTH (at 10 nM) stimulated ALP activity, induced RANKL mRNA expression and suppressed OPG mRNA expression in SaOS-2 cells, confirming its bi-directional effects on osteoblastic cells. Pre-treatment of SaOS-2 cells with genistein and oestrogen not only enhanced PTH-induced ALP activity, but also attenuated PTH up regulation of RANKL mRNA expression and PTH down regulation of OPG mRNA expression. Taken together, the present study provides the first evidence that genistein could modulate the actions of PTH in human osteoblastic SaOS-2 cells in an oestrogen-depleted condition.

  16. Exploring the decoupling and removal of dense material during lithospheric thickening as applicable to craton formation

    NASA Astrophysics Data System (ADS)

    Wood, R. J.; Cooper, C. M.

    2012-12-01

    Cratons are areas of continental crust and lithosphere that have not deformed for billions of years; thus, comprising the most stable regions on the Earth's surface. However, the processes that lead to craton formation introduce potential instabilities. For example, cratons formed via the stacking of buoyant oceanic lithosphere would pose some potentially serious buoyancy complications as the basaltic crust tends to transform into much denser eclogite at depth. Thus, if basaltic crust is a significant portion of buoyant oceanic lithosphere, the entire thickened package could be overwhelmed by the transition to eclogite. This could in turn promote instability, foundering and failure to produce thick cratonic lithosphere. Alternatively, forming thick cratonic lithosphere via the amalgamation of arc or continental material would also introduce instability. Achieving the required integrated buoyancy from island arc material also requires a secondary removal process of mafic/ultramafic cumulates during collision. This leads to several testable questions; how much dense material can the system maintain before becoming unstable? Does the relative depth of the dense material effect stability? Does the dense material need to be removed or can it be modified in some manner to maintain stability? If it can be modified, which process or processes can do so? We will present numerical models exploring one such modification process- the decoupling and removal of dense material during lithospheric thickening.

  17. New constraints on the upper mantle structure of the Slave craton from Rayleigh wave inversion

    NASA Astrophysics Data System (ADS)

    Chen, Chin-Wu; Rondenay, Stéphane; Weeraratne, Dayanthie S.; Snyder, David B.

    2007-05-01

    Rayleigh wave phase and amplitude data are analyzed to provide new insight into the velocity structure of the upper mantle beneath the Slave craton, in the northwestern Canadian Shield. We invert for phase velocities at periods between 20 s-142 s (with greatest sensitivity at depths of 28-200 km) using crossing ray paths from events recorded by the POLARIS broadband seismic network and the Yellowknife array. Phase velocities obtained for the Slave province are comparable to those from other cratons at shorter periods, but exceed the global average by ~2% at periods above 60 s, suggesting that the Slave craton may be an end member in terms of its high degree of mantle depletion. The one-dimensional inversion of phase velocities yields high upper-mantle S-wave velocities of 4.7 +/- 0.2 km/s that persist to 220 +/- 65 km depth and thus define the cratonic lithosphere. Azimuthal anisotropy is well resolved at all periods with a dominant fast direction of N59°E +/- 20°, suggesting that upper mantle anisotropy beneath the Slave craton is influenced by both lithospheric fabric and sub-lithospheric flow.

  18. Developing Early Warning Indicators for the San Francisco Unified School District. Youth Data Archive Issue Brief

    ERIC Educational Resources Information Center

    John W. Gardner Center for Youth and Their Communities, 2011

    2011-01-01

    San Francisco's Bridge to Success (BtS) initiative brings together the City and County of San Francisco, the San Francisco Unified School District (SFUSD), the City College of San Francisco (CCSF), and key community organizations to promote postsecondary success for underrepresented students. Partners agree that the first step in achieving this…

  19. Microbial biogeography of San Francisco Bay sediments

    NASA Astrophysics Data System (ADS)

    Lee, J. A.; Francis, C. A.

    2014-12-01

    The largest estuary on the west coast of North America, San Francisco Bay is an ecosystem of enormous biodiversity, and also enormous human impact. The benthos has experienced dredging, occupation by invasive species, and over a century of sediment input as a result of hydraulic mining. Although the Bay's great cultural and ecological importance has inspired numerous surveys of the benthic macrofauna, to date there has been almost no investigation of the microbial communities on the Bay floor. An understanding of those microbial communities would contribute significantly to our understanding of both the biogeochemical processes (which are driven by the microbiota) and the physical processes (which contribute to microbial distributions) in the Bay. Here, we present the first broad survey of bacterial and archaeal taxa in the sediments of the San Francisco Bay. We conducted 16S rRNA community sequencing of bacteria and archaea in sediment samples taken bimonthly for one year, from five sites spanning the salinity gradient between Suisun and Central Bay, in order to capture the effect of both spatial and temporal environmental variation on microbial diversity. From the same samples we also conducted deep sequencing of a nitrogen-cycling functional gene, nirS, allowing an assessment of evolutionary diversity at a much finer taxonomic scale within an important and widespread functional group of bacteria. We paired these sequencing projects with extensive geochemical metadata as well as information about macrofaunal distribution. Our data reveal a diversity of distinct biogeographical patterns among different taxa: clades ubiquitous across sites; clades that respond to measurable environmental drivers; and clades that show geographical site-specificity. These community datasets allow us to test the hypothesis that salinity is a major driver of both overall microbial community structure and community structure of the denitrifying bacteria specifically; and to assess

  20. Surface Curvature in Island Groups and Discontinuous Cratonic Structures

    NASA Astrophysics Data System (ADS)

    McDowell, M. S.

    2002-05-01

    The Canadian Archipelago includes eight major islands and a host of smaller ones. They are separated by water bodies, of varying widths attributable to glacial activity and ocean currents. Land form varies from relatively rugged mountains (~2000 m) in eastern, glacial, islands, to low lying western, similar to the continental topography adjacent. The Arctic region is thought to have been low average elevation before the Pleistocene. To a picture puzzler, it all looks like it fit together. Experimentally cutting apart the islands from large scale maps shows that the rough edges match fairly well. However, when those independent pieces are sutured together, without restraint, as in free air, the fit is far better. Far more importantly, they consistently form a noticeably concave surface. This tendency is not at all apparent in flat surface or computer screen manipulation; the pieces need to be "hand joined" or on a molded surface to allow the assembly to freely form as it will. Fitting together the coastlines above 60 \\deg north, from 120 \\deg west to 45 \\deg east, and comparing the resulting contracted area to the original, obtains an 8 percent area reduction. The curvature "humps" a trial planar section of 15 cms by 1.6 cm, a substantial difference in the radius of curvature. If you rashly suggest applying that formula globally, the resulting sphere would have a surface area of 4.7 x108,(down from 5 x108), and therefore radius of 6117 km, down from 6400, which is a rather preposterous conclusion. As nobody would believe it, I tested the idea elsewhere. The Huronian succession of six named cratons is adjacent on the south. I cut this map apart, too, and fit it together, once again getting a curvature, this time more pronounced. I am trying it with the Indonesian Archipelago, although this area has volcanic complications, and with Precambrian Basins in western Australia and Nimibia, Africa. Indications are - an essentially similar pattern of fit, but non uniform

  1. Supercontinents, True Polar Wander, and Paleogeography of the Slave Craton

    NASA Astrophysics Data System (ADS)

    Mitchell, Ross Nelson

    evidence in support of a long-lived, Ediacaran-aged hotspot. The consistency of paleocurrent directions derived from the Great Slave Supergroup argues against significant regional vertical-axis rotations and for large and rapid TPW to explain discordant paleomagnetic directions observed within section. The last frontier for paleomagnetic constraints on supercontinents, TPW, and the antiquity of plate tectonics is earliest Proterozoic time. Laurentia, one of Earth's oldest continents that formed at the core supercontinent Nuna, contains several cratons that have adequate paleomagnetic and geochronologic data with which to test for evidence of early TPW and relative plate motion, the hallmark of tectonics. Although past comparisons have been made between the Slave and Superior cratons at each "bookend" of Laurentia, new paleomagnetic data supported by baked contact tests allow for conclusive early Proterozoic reconstructions. Similar to periods following Proterozoic supercontinents Nuna and Rodinia, early Proterozoic time is characterized by large TPW oscillations and large-scale plate reorganizations prior to amalgamation, possibly indicating the presence of `Kenorland', an Archean supercontinent.

  2. Crustal velocity structure of western Dharwar Craton, South India

    NASA Astrophysics Data System (ADS)

    Sarkar, D.; Chandrakala, K.; Padmavathi Devi, P.; Sridhar, A. R.; Sain, K.; Reddy, P. R.

    2001-03-01

    A deep seismic sounding (DSS) experiment was carried out across the Indian shield in 1972-1975. Kaila et al. (Kaila, K.L., Roy Chowdhury, K., Reddy, P.R., Krishna, V.G., Hari Narain, Subbotin, S.I., Sollogub, V.B., Chekunov, A.V., Kharetchko, G.E., Lazarenko, M.A., Ilchenko T.V., 1979. Crustal structure along Kavali-Udipi profile in the Indian peninsular shield from deep seismic sounding. J. Geol. Soc. of Ind., 20, 307-333) presented a crustal depth section based on the interpretation of the analog seismic data. In this paper, we re-examine the crustal structure of the Western Dharwar Craton (WDC) by reprocessing the data of three major shot points. Kinematic 1-D inversion, followed by 2-D forward modeling of the first arrival refraction and a few persistent wide-angle reflection phases, was carried out to build, a first order two-dimensional velocity model of this segment of the profile. This model brings out a simple crustal velocity structure consisting of an upper and lower crust. The upper crust (velocity 6.0-6.2 km/s) is on average 23 km thick, which is underlain by a lower crust of velocity 6.8-7.0 km/s. The average Moho depth in this part is about 37-40 km, with higher-than-normal P n velocity of 8.4 km/s. A relatively deep Moho in this part of the Archean peninsular shield is associated with relatively low velocities in the lower crust, perhaps indicating absence of underplating in this region. Present results bring out the fact that the crust of WDC is not so typical as many other Archean crusts, in terms of both thickness and velocities.

  3. The Tropical Semiannual Oscillation (SAO) in Temperature and Ozone as Observed by the Microwave Limb Sounder (MLS)

    NASA Technical Reports Server (NTRS)

    Ray, E.; Holton, J. R.; Fishbein, E. F.; Froidevaux, L.; Waters, J. W.

    1994-01-01

    The first two years of MLS temperature and ozone data are used to examine the tropical upper stratospheric SAO. Time series analysis revealed the strongest amplitudes of the SAO to occur near the equator at 2 mb for temperature and 5 mb for ozone, consistent with previous observations.

  4. San Francisco, San Pablo Bay Area

    NASA Image and Video Library

    1994-09-30

    STS068-244-022 (30 September-11 October 1994) --- (San Francisco, San Pablo Bay Area) Photographed through the Space Shuttle Endeavour's flight deck windows, the heavily populated bay area is featured in this 70mm frame. The relatively low altitude of Endeavour's orbit (115 nautical miles) and the use of a 250mm lens on the Hasselblad camera allowed for capturing detail in features such as the Berkeley Marina (frame center). The region's topography is well depicted with the lowland areas heavily populated and the hills much more sparsely covered. The Oakland Hills in the right lower center appear to be re-vegetated after a devastating fire. The Golden Gate Recreation Area in the upper left also shows heavy vegetation. The three bridges across the main part of the bay and their connecting roads are prominent. Cultural features such as Golden Gate Park and the Presidio contrast with the gray of the city.

  5. Forecasting the Next Great San Francisco Earthquake

    NASA Astrophysics Data System (ADS)

    Rundle, P.; Rundle, J. B.; Turcotte, D. L.; Donnellan, A.; Yakovlev, G.; Tiampo, K. F.

    2005-12-01

    The great San Francisco earthquake of 18 April 1906 and its subsequent fires killed more than 3,000 persons, and destroyed much of the city leaving 225,000 out of 400,000 inhabitants homeless. The 1906 earthquake occurred on a km segment of the San Andreas fault that runs from the San Juan Bautista north to Cape Mendocino and is estimated to have had a moment magnitude m ,l 7.9. Observations of surface displacements across the fault were in the range m. As we approach the 100 year anniversary of this event, a critical concern is the hazard posed by another such earthquake. In this talk we examine the assumptions presently used to compute the probability of occurrence of these earthquakes. We also present the results of a numerical simulation of interacting faults on the San Andreas system. Called Virtual California, this simulation can be used to compute the times, locations and magnitudes of simulated earthquakes on the San Andreas fault in the vicinity of San Francisco. Of particular importance are new results for the statistical distribution of interval times between great earthquakes, results that are difficult or impossible to obtain from a purely field-based approach. We find that our results are fit well under most circumstances by the Weibull statistical distribution, and we compute waiting times to future earthquakes based upon our simulation results. A contrasting approach to the same problem has been adopted by the Working Group on California Earthquake Probabilities, who use observational data combined with statistical assumptions to compute probabilities of future earthquakes.

  6. ASTER Images San Francisco Bay Area

    NASA Image and Video Library

    2000-04-26

    These images of the San Francisco Bay region were acquired on March 3, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. Each covers an area 60 kilometers (37 miles) wide and 75 kilometers (47 miles) long. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image the Earth for the next 6 years to map and monitor the changing surface of our planet. Upper Left: The color infrared composite uses bands in the visible and reflected infrared. Vegetation is red, urban areas are gray; sediment in the bays shows up as lighter shades of blue. Thanks to the 15 meter (50-foot) spatial resolution, shadows of the towers along the Bay Bridge can be seen. Upper right: A composite of bands in the short wave infrared displays differences in soils and rocks in the mountainous areas. Even though these regions appear entirely vegetated in the visible, enough surface shows through openings in the vegetation to allow the ground to be imaged. Lower left: This composite of multispectral thermal bands shows differences in urban materials in varying colors. Separation of materials is due to differences in thermal emission properties, analogous to colors in the visible. Lower right: This is a color coded temperature image of water temperature, derived from the thermal bands. Warm waters are in white and yellow, colder waters are blue. Suisun Bay in the upper right is fed directly from the cold Sacramento River. As the water flows through San Pablo and San Francisco Bays on the way to the Pacific, the waters warm up. http://photojournal.jpl.nasa.gov/catalog/PIA02605

  7. At the craton edge: Geodynamic evolution of the southern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    DiCaprio, L.; Eaton, D. W. S.

    2016-12-01

    In the southern Canadian Cordillera, the thermal and mechanical interface with the craton may influence the geodynamic evolution of the lithosphere-asthenosphere system. Evidence including recent Rayleigh-wave tomography studies suggest that, beneath the southern Canadian Cordillera, the mantle lithosphere is virtually absent. Here, the boundary between craton and Cordillera also marks a step change in measured surface heat flux and a westward termination of magnetic anomalies. This study provides a numerical simulation of lithospheric-mantle removal by geodynamic processes that include delamination, viscous erosion, and mantle dripping. An additional constraint to the geodynamic model comes from thermochronologic data demonstrating long wavelength uplift of the cordilleran plateau in the Eocene. We have developed a suite of 2D visco-plastic models of a transect through the southern Canadian Cordillera and North American Craton. Sensitivity tests elucidate a range of geodynamic models that are consistent with tomographic results and the observed uplift history.

  8. African hot spot volcanism: small-scale convection in the upper mantle beneath cratons.

    PubMed

    King, S D; Ritsema, J

    2000-11-10

    Numerical models demonstrate that small-scale convection develops in the upper mantle beneath the transition of thick cratonic lithosphere and thin oceanic lithosphere. These models explain the location and geochemical characteristics of intraplate volcanos on the African and South American plates. They also explain the presence of relatively high seismic shear wave velocities (cold downwellings) in the mantle transition zone beneath the western margin of African cratons and the eastern margin of South American cratons. Small-scale, edge-driven convection is an alternative to plumes for explaining intraplate African and South American hot spot volcanism, and small-scale convection is consistent with mantle downwellings beneath the African and South American lithosphere.

  9. East asian gold: Deciphering the anomaly of phanerozoic gold in precambrian cratons

    USGS Publications Warehouse

    Goldfarb, R.J.; Hart, C.; Davis, G.; Groves, D.

    2007-01-01

    Early Cretaceous orogenic gold deposits in eastern Asia are globally unique in that large Phanerozoic lode gold deposits occur in Archean-Paleoproterozoic cratons. In the northern Pacific region, ca. 125 Ma orogenic gold deposits in the North China, Yangzte, and Siberian craton margins, as well as in young terranes in California, may ultimately relate to the giant Cretaceous mantle plume in the southern Pacific basin and the relatively rapid tectonic consequences along both continental margins from resulting Pacific plate reconfigurations. In eastern Asia, such consequences include reactivation of and fluid flow along major fault systems, with fluid focusing into simultaneously forming, isolated core complexes of uncertain genesis. Deposition of gold ores in previously devolatilized high-grade Precambrian metamorphic rocks requires an exotic source of ore fluid, most likely subducted Mesozoic oceanic crust and/or overlying sediment. An implication is that Phanerozoic metamorphic core complexes in other destabilized craton margins could host large gold resources. ?? 2007 by Economic Geology.

  10. PdS Receiver Function Evidence for Mafic Underplating in the Superior Craton: A Discussion About Cratonic Stabilization

    NASA Astrophysics Data System (ADS)

    Thurner, S.; Niu, F.; Margolis, R. E.; Levander, A.; Lee, C. T.

    2014-12-01

    The Trans-Hudson orogen (THO) in the north central United States represents a major suturing event between the Wyoming and Superior Archean provinces. It is bounded to the south by the NE-SW striking Yavapai province, which was accreted along the southeastern margin of North America between 1.71 and 1.68 Ga and was one of a series of major collisional events responsible for the assembly of Laurentia. In this study, PdS teleseismic receiver functions were used to investigate the deep crustal structure associated with these collisions. Using data from over 800 broadband seismic stations distributed throughout the Great Plains/Midcontinent region, we calculated .5 Hz receiver functions using 245 M > 6.0 teleseismic events. The receiver functions were then CCP (common conversion point) stacked to create a 3D image volume. Profiles through this image volume show evidence of crustal scale thrusting of the Wyoming province in the west over the Superior province in the east and structural underplating associated with the Yavapai-Superior boundary. We also performed a density analysis of the region using the 2p1s and 0p1s receiver function phases from 233 stations. These data indicate a relatively low Moho density contrast throughout the THO and northern Yavapai region associated with a region of thickened crust (> 50 km), which we interpret to be evidence of a dense lower crustal layer that may be the result mafic underplating. Additionally, we investigate the role that this dense layer may have on the stabilization of the Superior craton and others relative to compositionally and thermally derived density variations in the mantle lithosphere.

  11. Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction

    NASA Astrophysics Data System (ADS)

    Pilet, S.; Müntener, O.; Jean, G.; Schoene, B.; Schaltegger, U.

    2016-12-01

    The temporal coincidence between LIPs and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here, we present a synthesis of stratigraphic constraints on the Triassic-Jurassic and Pliensbachian-Toarcian boundaries combined with geochronological data demonstrating that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. As current hypothesis for LIPs seems unable to produce these successive climatic changes, we evaluate an alternative suggesting that the initial cooling could be due to gas release during the initial thermal erosion of the cratonic lithosphere due to emplacement of the CAMP and Karoo-Ferrar volcanic provinces. Karoo and CAMP areas were underlain by thick lithosphere (>200 km) prior to continental break up. Even in presence of abnormal potential mantle temperature, the presence of thick lithosphere excludes significant melting of the asthenospheric mantle without initial stage of thermal erosion of the cratonic lithosphere. Various studies on Kaapvaal craton have shown that sulfide minerals are enclosed in the basal part of the cratonic lithosphere. We argue that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere causing global cooling and eustatic regression, which was followed by warming/transgression associated with the progressive increase of CO2 in the atmosphere associated to LIPs emission. We suggest that the nature of the underlying lithosphere during large LIP eruption exerts an important control on the consequences at the Earth's surface. This model offers an explanation for why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere.

  12. Magnetotelluric characterization of the northern margin of the Yilgarn Craton (Western Australia)

    NASA Astrophysics Data System (ADS)

    Piña-Varas, Perla; Dentith, Michael

    2017-04-01

    The northern margin of the Yilgarn Craton (Western Australia) was deformed during the convergence and collision with the Pilbara Craton and the intervening Glenburgh Terrain that created the Capricorn Orogen. The Yilgarn Craton is one of the most intensively mineralised areas of continental crust with world class deposits of gold and nickel. However, the region to its north has surprisingly few deposits. Cratonic margins are considered to be key indicators of prospectivity at a regional scale. The northern limit of the Yilgarn Craton within the Capricorn Orogen is not well resolved at date because of overlying Proterozoic sedimentary basins. We present here some of the results of an extensive magnetotelluric (MT) study that is being performed in the area. This study is a component of large multi-disciplinary geoscience project on the 'Distal Footprints of Giant Ore Systems' in the Capricorn Orogen. The MT dataset consists of a total of 240 broadband magnetotelluric stations (BBMT) and 84 long period stations (LMT). Analysis of the dataset reveals a clear 3-D geoelectrical behaviour and extreme complexity for most of the sites, including an extremely high number of sites with phases out-of-quadrant at long periods. 3-D inverse modelling of the MT data shows high resistivity Archean units and low resistivity Paleoproterozoic basins, including very low resistivity structures at depth. These strong resistivity contrasts allow us to successfully map northern margin of the Yilgarn Craton beneath basin cover, as well as identifying major lateral conductivity changes in the deep crust suggestive of different tectonic blocks. Upper crustal conductive zones can be correlated with faults on seismic reflection data. Our results suggest MT surveys are a useful tool for regional-scale exploration in the study area and in area of thick cover in general.

  13. Constant average olivine Mg# in cratonic mantle reflects Archaean mantle melting to the exhaustion of orthopyroxene

    NASA Astrophysics Data System (ADS)

    Bernstein, S.; Kelemen, P. B.; Hanghoj, K.

    2006-12-01

    Shallow (garnet-free) cratonic mantle, occurring as xenoliths in kimberlites and alkaline basaltic lavas, has high Mg# (100x Mg/(Mg+Fe)>92) and is poor in Al and Ca compared to off-cratonic mantle. Many xenoliths show rhenium-depletion age of > 3 Ga, and are thus representative of depleted mantle peridotite that form an integral part of the stable nuclei of Archaean (2.5-3.8 Ga) cratons. Accordingly, the depleted composition of the xenolith suites is linked to Archaean melt extraction events. We have compiled data for many suites of shallow cratonic mantle xenoliths worldwide, including samples from cratons of Kaapvaal, Tanzania, Siberia, Slave, North China and Greenland, and encompassing both the classic orthopyroxene-rich peridotites of Kaapvaal and orthopyroxene-poor peridotites from Greenland. The suites show a remarkably small range in average olivine Mg# of 92.8 +/- 0.2. Via comparison with data for experimental melting of mantle peridotite compositions, we explain consistent olivine Mg# in the shallow cratonic mantle as the result of mantle melting and melt extraction to the point of orthopyroxene exhaustion, leaving a nearly monomineralic olivine, or dunitic, residue. Experimental data for peridotite melting at pressures less than 4 GPa and data on natural rocks suggest that mantle olivine has a Mg# of about 92.8 at the point of orthopyroxene exhaustion. If the melt extraction was efficient, no further melting could take place without a considerable temperature increase or melt/fluid flux through the dunite residue at high temperatures. While the high Mg#, dunite-dominated xenolith suites from e.g. Greenland represent simple residues from mantle melting, the orthopyroxene-rich xenolith suites with identical Mg# as known from e. g. Kaapvaal must reflect some additional processes. We envisage their derivation from dunite protoliths via subsequent melt/rock reaction with silica-rich melts or, in some cases, possibly as residues at higher average melting

  14. Paleomagnetism of the early Paleoproterozoic, volcanic Hekpoort Formation (Transvaal Supergroup) of the Kaapvaal craton, South Africa

    NASA Astrophysics Data System (ADS)

    Humbert, F.; Sonnette, L.; de Kock, M. O.; Robion, P.; Horng, C. S.; Cousture, A.; Wabo, H.

    2017-02-01

    The Kaapvaal craton (South Africa) was the host of several major magmatic events during the Paleoproterozoic, including the volcanic Hekpoort and Ongeluk formations. Their possible comagmatic origin is the subject of a long debate. We performed a paleomagnetic study of the Hekpoort Formation to get a primary pole can be compared with the available paleopole of the Ongeluk Formation, but also to contribute to the apparent pole wander path of the Kaapvaal craton. Characterization of magnetic mineralogy by 3-axis thermal demagnetization of IRM and magnetic susceptibility vs temperature points out magnetite as the main remanence carrier in most samples.

  15. Continental lithospheric evolution: Constraints from the geochemistry of felsic volcanic rocks in the Dharwar Craton, India

    NASA Astrophysics Data System (ADS)

    Manikyamba, C.; Ganguly, Sohini; Saha, Abhishek; Santosh, M.; Rajanikanta Singh, M.; Subba Rao, D. V.

    2014-12-01

    Felsic magmatism associated with ocean-ocean and ocean-continent subduction processes provide important evidence for distinct episodes of crust-generation and continental lithospheric evolution. Rhyolites constitute an integral component of the tholeiitic to calc-alkaline basalt-andesite-dacite-rhyolite (BADR) association and contribute to crustal growth processes at convergent plate margins. The evolution of the Dharwar Craton of southern peninsular India during Meso- to Neoarchean times was marked by extensive development of greenstone belts. These granite-greenstone terranes have distinct volcano-sedimentary associations consistent with their geodynamic setting. The present study deals with geochemistry of rhyolites from the Chitradurga-Shimoga greenstone belts of western (WDC) and the Gadwal-Kadiri greenstone belts of eastern (EDC) sectors of Dharwar Craton to compare and evaluate their petrogenesis and geodynamic setting and their control on the continental lithospheric evolution of the Dharwar Craton. At a similar range of SiO2, Al2O3, Fe2O3, the rhyolites of WDC are more potassic, whereas the EDC rhyolites are more sodic and less magnesian with slight increase in TiO2. Minor increase in MgO content of WDC rhyolites reflects their ferromagnesian trace elements which are comparatively lower in the rhyolites of EDC. The relative enrichment in LILE (K, Rb) and depletion in HFSE (Nb, Ta, Zr, Hf) marked by negative Nb-Ta, Zr-Hf and Ti anomalies endorse the convergent margin processes for the generation of rhyolites of both the sectors of Dharwar Craton. The high silica potassic rhyolites of Shimoga and Chitradurga greenstone belts of WDC showing prominent negative Eu and Ti anomalies, flat HREE patterns correspond to Type 3 rhyolites and clearly point towards their generation and emplacement in an active continental margin environment. The geochemical characteristics of Gadwal and Kadiri rhyolites from eastern Dharwar Craton marked by aluminous compositions with

  16. Seismic evidence for stratification in composition and anisotropic fabric within the thick lithosphere of Kalahari Craton

    NASA Astrophysics Data System (ADS)

    Sodoudi, F.; Yuan, X.; Kind, R.; Lebedev, S.; Tilmann, F. J.

    2013-12-01

    S receiver functions obtained from the data of 97 seismic stations present evidence for the existence of a layered and thick lithosphere beneath the Kalahari Craton. We identified three negative discontinuities within the lithosphere of the Archean cratons and Proterozoic mobile belts of southern Africa. We also employed a novel combination of SRFs and surface-wave analysis to constrain the anisotropic properties of the lithosphere and its internal layering. Our results show that frozen-in anisotropy and compositional changes can generate sharp Mid-Lithospheric Discontinuities (MLD) at depths of 85 and 150-200 km, respectively. We found that a 50 km thick anisotropic layer containing 3% S wave anisotropy and with a fast-velocity axis different from that in the layer beneath can account for the first MLD at about 85 km depth. This depth is largely consistent with that of 8° discontinuity suggested as a global characteristic of cratonic lithosphere. Significant correlation between the depths of an apparent boundary separating the depleted and metasomatic refertilized lithosphere, as inferred from chemical tomography, and those of our second MLD (at 150-200 km depth) led us to characterize this negative discontinuity as a compositional boundary, most likely due to the modification of the cratonic mantle lithosphere by magma infiltration. We detected this MLD at a depth of about 150 km beneath the Zimbabwe Craton and Limpopo belt with a steep deepening to about 200 km underneath the Kaapvaal Craton and its passive margin. The deepening of this boundary is spatially correlated with the surficial expression of the ancient Thabazimbi-Murchison Lineament (TML). This may imply that the translithospheric TML isolates the lithospheric block of the relatively younger Limpopo terrane from that of the ancient Kaapvaal terrane. Finally, the largest velocity contrast (3.6-4.7%) is observed at a boundary located at depths of 260-280 km beneath the Archean domains and the older

  17. Palaeomagnetism of the early Palaeoproterozoic, volcanic Hekpoort Formation (Transvaal Supergroup) of the Kaapvaal craton, South Africa

    NASA Astrophysics Data System (ADS)

    Humbert, F.; Sonnette, L.; de Kock, M. O.; Robion, P.; Horng, C. S.; Cousture, A.; Wabo, H.

    2017-05-01

    The Kaapvaal craton (South Africa) was the host of several major magmatic events during the Palaeoproterozoic, including the volcanic Hekpoort and Ongeluk Formations. Their possible comagmatic origin is the subject of a long debate. We performed a palaeomagnetic study of the Hekpoort Formation to be compared with the available palaeopole of the Ongeluk Formation, but also to contribute to the apparent polar wander path of the Kaapvaal craton. Characterization of magnetic mineralogy by three-axis thermal demagnetization of isothermal remanent magnetization and magnetic susceptibility versus temperature points out magnetite as the main remanence carrier in most samples.

  18. 27 CFR 9.157 - San Francisco Bay.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Mountain, California, scale 1:24,000, dated 1956, Photorevised 1980; (25) Half Moon Bay, California, scale... Francisco South, Montara Mountain, Half Moon Bay, San Gregorio, Pigeon Point, Franklin Point, Año Nuevo and...

  19. 27 CFR 9.157 - San Francisco Bay.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Mountain, California, scale 1:24,000, dated 1956, Photorevised 1980; (25) Half Moon Bay, California, scale... Francisco South, Montara Mountain, Half Moon Bay, San Gregorio, Pigeon Point, Franklin Point, Año Nuevo and...

  20. 27 CFR 9.157 - San Francisco Bay.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Mountain, California, scale 1:24,000, dated 1956, Photorevised 1980; (25) Half Moon Bay, California, scale... Francisco South, Montara Mountain, Half Moon Bay, San Gregorio, Pigeon Point, Franklin Point, Año Nuevo and...

  1. 27 CFR 9.157 - San Francisco Bay.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Mountain, California, scale 1:24,000, dated 1956, Photorevised 1980; (25) Half Moon Bay, California, scale... Francisco South, Montara Mountain, Half Moon Bay, San Gregorio, Pigeon Point, Franklin Point, Año Nuevo and...

  2. 27 CFR 9.157 - San Francisco Bay.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Mountain, California, scale 1:24,000, dated 1956, Photorevised 1980; (25) Half Moon Bay, California, scale... Francisco South, Montara Mountain, Half Moon Bay, San Gregorio, Pigeon Point, Franklin Point, Año Nuevo and...

  3. RadNet Air Data From San Francisco, CA

    EPA Pesticide Factsheets

    This page presents radiation air monitoring and air filter analysis data for San Francisco, CA from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  4. 22. Photocopy of photograph (from San Francisco Chronicle Collection) Photographer ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. Photocopy of photograph (from San Francisco Chronicle Collection) Photographer unknown, Date unknown SIDE VIEW OF CHURCH - Mission San Miguel Arcangel, Highway 101, San Miguel, San Luis Obispo County, CA

  5. 18. Photocopy of photograph (from De Young Museum, San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. Photocopy of photograph (from De Young Museum, San Francisco, CA. c. 1900) Photographer unknown, February 1940 EXTERIOR VIEW FROM NORTHEAST - Mission San Miguel Arcangel, Highway 101, San Miguel, San Luis Obispo County, CA

  6. Salinity and Flow Monitoring in the San Francisco Bay Delta

    EPA Pesticide Factsheets

    This report describes the utility and approximate cost of expanding the salinity water quality monitoring network along the axis of the San Francisco Estuary from Suisun Bay to Rio Vista on the Sacramento River.

  7. 10. Historic American Buildings Survey From Gleason Collection San Francisco ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. Historic American Buildings Survey From Gleason Collection San Francisco College for Women Original: About 1884 Re-photo: March 1940 VIEW FROM SOUTHWEST - Mission Nuestra Senora de la Soledad, Soledad, Monterey County, CA

  8. 2. Historic American Buildings Survey National Park Service San Francisco, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Historic American Buildings Survey National Park Service San Francisco, California Year Built: 1835 Photo Taken: 1939 GENERAL VIEW - Pacific House, 200-222 Calle Principal, Monterey, Monterey County, CA

  9. 24. Historic American Buildings Survey From Gleason Collection San Francisco ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. Historic American Buildings Survey From Gleason Collection San Francisco College for Women Original: About 1895 Re-photo: March 1940 CHAPEL - Mission Nuestra Senora de la Soledad, Soledad, Monterey County, CA

  10. "Conscientizacao" through Graffiti Literacies in the Streets of a Sao Paulo Neighborhood: An Ecosocial Semiotic Perspective

    ERIC Educational Resources Information Center

    Iddings, Ana Christina DaSilva; McCafferty, Steven G.; da Silva, Maria Lucia Teixeira

    2011-01-01

    In this study, we applied an ecosocial semiotic theoretical framework to the analysis of graffiti literacies in the Vila Madalena neighborhood of Sao Paulo, Brazil, to inquire about the nature and processes of "conscientizacao" (critical awareness) for adult street dwellers who had no or little ability to read and write (as traditionally…

  11. The People Speak Their Word: Learning to Read and Write in Sao Tome and Principe.

    ERIC Educational Resources Information Center

    Freire, Paulo

    1981-01-01

    Freire reflects on his role as consultant to the Adult Literacy Program in Sao Tome and Principe. Emphasizing the political aspects of pedagogy, he describes how adults learn to read and write, as well as to think critically and participate in national development. (SK)

  12. Contemporary Art at School: The Educational Sector at the Sao Paulo Biennial.

    ERIC Educational Resources Information Center

    De Almeida, Ana Cristina Pereira

    1989-01-01

    Describes how the Educational Sector of the Sao Paulo Biennial assists art teachers in introducing contemporary art into the schools. Outlines how students were observed viewing the exhibition and creating artworks. Describes how training programs and materials were provided to help the schools. (KM)

  13. Paulo Freire as Secretary of Education in the Municipality of Sao Paulo.

    ERIC Educational Resources Information Center

    Torres, Carlos Alberto

    1994-01-01

    Examines educational policy formation in Sao Paulo, 1989-92, under the leadership of Paulo Freire. Explores theoretical and policy controversies surrounding the diminishing role of the state in Latin America, the impact of social movements on educational policymaking, and the limits and possibilities of democratic-socialist perspectives in…

  14. The Social Distribution of Reports of Health-Related Concerns among Adolescents in Sao Paulo, Brazil

    ERIC Educational Resources Information Center

    de Moura, S. L.

    2004-01-01

    This study investigated the health-related concerns of adolescents living on streets as compared to poor and privileged adolescents living with their families in Sao Paulo, Brazil. The different groups of respondents were similar in terms of individuals' fear of disease and lack of concern about health in old age. AIDS and cancer were feared by…

  15. FAP Group Supervision: Reporting Educational Experiences at the University of Sao Paulo, Brazil

    ERIC Educational Resources Information Center

    Wielenska, Regina Christina; Oshiro, Claudia Kami Bastos

    2012-01-01

    The present article describes and analyzes educational experiences related to the teaching of FAP for psychology graduate students and psychiatry residents at the University of Sao Paulo. The first experience involved psychology graduate students and includes an example of the shaping process occurring within the supervisor-supervisee…

  16. "Conscientizacao" through Graffiti Literacies in the Streets of a Sao Paulo Neighborhood: An Ecosocial Semiotic Perspective

    ERIC Educational Resources Information Center

    Iddings, Ana Christina DaSilva; McCafferty, Steven G.; da Silva, Maria Lucia Teixeira

    2011-01-01

    In this study, we applied an ecosocial semiotic theoretical framework to the analysis of graffiti literacies in the Vila Madalena neighborhood of Sao Paulo, Brazil, to inquire about the nature and processes of "conscientizacao" (critical awareness) for adult street dwellers who had no or little ability to read and write (as traditionally…

  17. The Social Distribution of Explanations of Health and Illness among Adolescents in Sao Paulo, Brazil.

    ERIC Educational Resources Information Center

    de Moura, Sergio Luiz; Harpham, Trudy; Lyons, Michal

    2003-01-01

    Investigates explanations of health and illness among adolescents from three socio-economic backgrounds in Sao Paulo, Brazil. The findings showed that adolescents from different socio-economic conditions draw upon similar explanatory models to make sense of health and illness. The findings suggest a need for health professionals to be sensitive to…

  18. Reengineering Electrical Engineering Undergraduate Laboratories at Escola Politecnica, University of Sao Paulo.

    ERIC Educational Resources Information Center

    Seabra, Antonio C.; Consonni, Denise

    Brazilian engineering schools are under a strict program to reengineer their courses with the financial support of the federal agencies. At the electronic engineering department at the University of Sao Paulo, this process started by modifying the Basic Electricity and Electronic Laboratories. This paper describes the new structure of these labs…

  19. The new structure of the gas industry in the State of Sao Paulo

    SciTech Connect

    Neto, J.A.J.

    1998-07-01

    The rapidly increasing availability of natural gas is leading to a significant increase in the importance of the gas industry in Brazil. This new era is already causing major changes in the existing gas distribution companies. Gas distribution concessions are a natural monopoly and the growth in demand for this energy source will require that these growing concessions are regulated. The south/south-east of Brazil is the center of the country's industrial base and the State of Sao Paulo is where most of the manufacturing activity is located. In addition, natural gas from Bolivia is scheduled to arrive in the State of Sao Paulo at the end of 1998. These two facts combined will mean major changes in the operations of manufacturing industry and in the gas supply business. Comparing the experience faced by other countries where a competitive environment in the gas industry has been introduced with privatization programs and the dismantlement of monopolies, this paper attempts to look into the future of the natural gas industry in the State of Sao Paulo in respect to the possible regulation that might be applicable, focusing on the new regulatory framework proposed to the gas industry sector and the perspectives for the introduction of the competition in gas industry in the State of Sao Paulo.

  20. The diameter of 88 Thisbe from its occultation of SAO 187124

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Franz, O. G.; White, N. M.; Bowell, E.; Klemola, A.; Elliott, R. C.; Smethells, W. G.; Price, P. M.; Mckay, C. P.

    1982-01-01

    The 7 October, 1981 occultation of SAO 187124 by 88 Thisbe was observed at twelve sites. The occultation observations, together with information about the asteroid's light curve, gives a mean diameter for Thisbe of 232 + or - 10 km. This value is 10 percent larger than the previously published radiometric diameter of Thisbe.

  1. The People Speak Their Word: Learning to Read and Write in Sao Tome and Principe.

    ERIC Educational Resources Information Center

    Freire, Paulo

    1981-01-01

    Freire reflects on his role as consultant to the Adult Literacy Program in Sao Tome and Principe. Emphasizing the political aspects of pedagogy, he describes how adults learn to read and write, as well as to think critically and participate in national development. (SK)

  2. The Social Distribution of Explanations of Health and Illness among Adolescents in Sao Paulo, Brazil.

    ERIC Educational Resources Information Center

    de Moura, Sergio Luiz; Harpham, Trudy; Lyons, Michal

    2003-01-01

    Investigates explanations of health and illness among adolescents from three socio-economic backgrounds in Sao Paulo, Brazil. The findings showed that adolescents from different socio-economic conditions draw upon similar explanatory models to make sense of health and illness. The findings suggest a need for health professionals to be sensitive to…

  3. Tissue transglutaminase (TG2) activity regulates osteoblast differentiation and mineralization in the SAOS-2 cell line.

    PubMed

    Yin, Xiaoxue; Chen, Zhongqiang; Liu, Zhongjun; Song, Chunli

    2012-08-01

    Tissue transglutaminase (type II, TG2) has long been postulated to directly promote skeletal matrix calcification and play an important role in ossification. However, limited information is available on the expression, function and modulating mechanism of TG2 during osteoblast differentiation and mineralization. To address these issues, we cultured the well-established human osteosarcoma cell line SAOS-2 with osteo-inductive conditioned medium and set up three time points (culture days 4, 7, and 14) to represent different stages of SAOS-2 differentiation. Osteoblast markers, mineralization, as well as TG2 expression and activity, were then assayed in each stage. Furthermore, we inhibited TG activity with cystamine and then checked SAOS-2 differentiation and mineralization in each stage. The results showed that during the progression of osteoblast differentiation SAOS-2 cells presented significantly high levels of osteocalcin (OC) mRNA, bone morphogenetic protein-2 (BMP-2) and collagen I, significantly high alkaline phosphatase (ALP) activity, and the increased formation of calcified matrix. With the same tendency, TG2 expression and activity were up-regulated. Furthermore, inhibition of TG activity resulted in a significant decrease of OC, collagen I, and BMP-2 mRNA and of ALP activity and mineralization. This study demonstrated that TG2 is involved in osteoblast differentiation and may play a role in the initiation and regulation of the mineralization processes. Moreover, the modulating effects of TG2 on osteoblasts may be related to BMP-2.

  4. Contemporary Art at School: The Educational Sector at the Sao Paulo Biennial.

    ERIC Educational Resources Information Center

    De Almeida, Ana Cristina Pereira

    1989-01-01

    Describes how the Educational Sector of the Sao Paulo Biennial assists art teachers in introducing contemporary art into the schools. Outlines how students were observed viewing the exhibition and creating artworks. Describes how training programs and materials were provided to help the schools. (KM)

  5. Paulo Freire as Secretary of Education in the Municipality of Sao Paulo.

    ERIC Educational Resources Information Center

    Torres, Carlos Alberto

    1994-01-01

    Examines educational policy formation in Sao Paulo, 1989-92, under the leadership of Paulo Freire. Explores theoretical and policy controversies surrounding the diminishing role of the state in Latin America, the impact of social movements on educational policymaking, and the limits and possibilities of democratic-socialist perspectives in…

  6. Inhibition of focal adhesion kinase induces apoptosis in human osteosarcoma SAOS-2 cells.

    PubMed

    Wang, Jialiang; Zu, Jianing; Xu, Gongping; Zhao, Wei; Jinglong, Yan

    2014-02-01

    Focal adhesion kinase (FAK), a non-receptor tyrosine kinase protein, acts as an early modulator of integrin signaling cascade, regulating basic cellular functions. In transformed cells, unopposed FAK signaling has been considered to promote tumor growth, progression, and metastasis. The aim of this study was to assess the role of focal adhesion kinase in human osteosarcoma SAOS-2 cells. SAOS-2 cells were transfected with PGPU6/GFP/shNC, and PGPU6/GFP/FAK-334 (shRNA-334), respectively. Expression of FAK was detected by real-time PCR and western blots. MTT assay was used to examine changes in cell proliferation. Cell apoptosis was analyzed by flow cytometry. The expression of caspase-3,-7,-9 was measured by Western blots. The expression of FAK in SAOS-2 cells significantly decreased in shRNA-334 group contrast to the control group (P < 0.01). Cells proliferation was inhibited by shRNA-334 and shRNA-334 + cisplatin, and the effects were clearly enhanced when cells treated with the anticancer agents. The level of cell apoptosis in shRNA-334 and shRNA-334 + cisplatin group was higher than in the control group (P < 0.01). The current data support evidence that down-regulation of FAK could induce SAOS-2 apoptosis through the caspase-dependent cell death pathway. Inhibition of the kinases may be important for therapies designed to enhance the apoptosis in osteosarcoma.

  7. The Social Distribution of Reports of Health-Related Concerns among Adolescents in Sao Paulo, Brazil

    ERIC Educational Resources Information Center

    de Moura, S. L.

    2004-01-01

    This study investigated the health-related concerns of adolescents living on streets as compared to poor and privileged adolescents living with their families in Sao Paulo, Brazil. The different groups of respondents were similar in terms of individuals' fear of disease and lack of concern about health in old age. AIDS and cancer were feared by…

  8. Tissue transglutaminase (TG2) activity regulates osteoblast differentiation and mineralization in the SAOS-2 cell line

    PubMed Central

    Yin, Xiaoxue; Chen, Zhongqiang; Liu, Zhongjun; Song, Chunli

    2012-01-01

    Tissue transglutaminase (type II, TG2) has long been postulated to directly promote skeletal matrix calcification and play an important role in ossification. However, limited information is available on the expression, function and modulating mechanism of TG2 during osteoblast differentiation and mineralization. To address these issues, we cultured the well-established human osteosarcoma cell line SAOS-2 with osteo-inductive conditioned medium and set up three time points (culture days 4, 7, and 14) to represent different stages of SAOS-2 differentiation. Osteoblast markers, mineralization, as well as TG2 expression and activity, were then assayed in each stage. Furthermore, we inhibited TG activity with cystamine and then checked SAOS-2 differentiation and mineralization in each stage. The results showed that during the progression of osteoblast differentiation SAOS-2 cells presented significantly high levels of osteocalcin (OC) mRNA, bone morphogenetic protein-2 (BMP-2) and collagen I, significantly high alkaline phosphatase (ALP) activity, and the increased formation of calcified matrix. With the same tendency, TG2 expression and activity were up-regulated. Furthermore, inhibition of TG activity resulted in a significant decrease of OC, collagen I, and BMP-2 mRNA and of ALP activity and mineralization. This study demonstrated that TG2 is involved in osteoblast differentiation and may play a role in the initiation and regulation of the mineralization processes. Moreover, the modulating effects of TG2 on osteoblasts may be related to BMP-2. PMID:22527131

  9. Landscape risk factors for attacks of vampire bats on cattle in Sao Paulo, Brazil.

    PubMed

    Gomes, Murilo Novaes; Monteiro, Antonio Miguel Vieira; Lewis, Nicola; Gonçalves, Celso Alberto; Filho, Vladimir de Souza Nogueira

    2010-02-01

    Vampire-bat (Desmodus rotundus) attacks on cattle are a major concern for cattle-raising area. Blood loss and paralytic rabies due to bat bites can impose severe losses on the livestock. We took four municipalities inside the Sao Joao da Boa Vista veterinary district (Sao Paulo, Brazil) as a study area and tested a set of landscape features for spatial correlation with distance to areas in which vampire-bat attacks on cattle were documented. Bat- and cattle-related data from the Sao Paulo State Rabies Control Program were used. Landscape data (first-order rivers and their tributaries, main roads, railways and urban areas) were obtained from official cartographic agencies; forest, sugarcane and pasture data were acquired from remote-sensing mappings. The study area was taken as a grid split into 178 cells. Each 4kmx4km cell was filled with bat, cattle and landscape data. Our analysis detected that grid cells that were closer to areas of bat attacks on cattle had higher cattle density and a greater percentage of the land committed to sugarcane cropping, and were close to forest fragments. These results shed light on the need for rethink the Rabies Control Program strategies for defining the surveillance of vampire-bat populations and rabies control in the state of Sao Paulo, Brazil.

  10. Building early Archean cratons from recycled Hadean crust

    NASA Astrophysics Data System (ADS)

    O'Neil, J.; Carlson, R. W.; Boyet, M.

    2013-12-01

    The formation of Earth's early crust and the geological processes leading to creation and preservation of stable Archean cratons are still poorly understood. Archean terrains are dominated by felsic Tonalite-Trondhjemite-Granodiorite (TTG) rocks. These felsic rocks however, cannot be directly produced from melting of the mantle but must instead be derived from the melting of an older mafic precursor. Despite growing evidence for a basaltic >4.3 Ga primordial crust on Earth, there are only a few occurrences of zircons older than 4.0 Ga; in the Jack Hills conglomerates and in the Acasta gneisses. Only after ~3.8 Ga does the zircon record become more prominent. The zircon age distribution in itself suggests a long quiescence period of over half a billion years before the mafic primitive crust was extensively recycled to produce a significant amount of felsic magma. The Nuvvuagittuq greenstone belt (NGB) provides a glimpse at the nature of the mafic primitive crust. The mafic rocks from the Nuvvuagittuq greenstone belt (NGB), called the Ujaraaluk unit, have 146Sm-142Nd systematics consistent with them being formed in the Hadean, between 4.3 and 4.4 Ga. The NGB also comprises multiple generations of TTG ranging from 3.75 Ga to 3.35 Ga. Despite the fact that the mafic and felsic lithologies of the NGB show strong evidence of disturbance in the 147Sm-143Nd and 176Lu-177Hf long-lived isotopic systems, the NGB TTGs yield 142Nd and 182W anomalies that can be only generated in the Hadean. Moreover, zircons from the 3.35 to 3.65 TTGs have strongly subchondritic initial ɛHf values and display an ɛHf vs. age array consistent with their derivation from a Hadean mafic precursor. The NGB TTGs appear to have been formed primarily from melting of a source compositionally similar to the 4.4 Ga Ujaraaluk unit. The crustal history recorded in the NGB seems to be similar to the early crustal evolution recorded in the Jack Hills Hadean zircons where reworking of a >4.3 Ga enriched

  11. An Integrated Crustal Analysis of Craton-Terrane Transition

    NASA Astrophysics Data System (ADS)

    Contenti, S. M.; Gu, Y. J.; Shen, L.

    2012-12-01

    velocities along the Thorsby/Rimbey domains. The proximity of these two domains to the STZ may shed new light on the spatial variability of subduction during the Proterozoic era. The combination of crustal depth, velocity, Vp/Vs ratios and anisotropy enables a careful re-examination of the existing tectonic model regarding the domain formation and reworking near the western edge of the North American Craton.

  12. The Hales discontinuity and upper mantle anisotropy beneath cratons

    NASA Astrophysics Data System (ADS)

    Musacchio, G.; White, D. J.; Thomson, C. J.

    2003-04-01

    Seismic velocity discontinuities are commonly found within the upper 100 km of the mantle lithosphere, with great variability in their depth, lateral extent, and the polarity of velocity jump. Among the more commonly observed is the Hales discontinuity, identified in a variety of tectonic environments, and commonly associated with a high-velocity, highly reflective and sometimes anisotropic layer. In the Archean Western Superior Province of the Canadian Shield, long range R/WAR profiling gives a high-resolution estimate of the mantle V_P in the shallow upper mantle, providing a more certain determination of the nature of the Hales dicontinuity. Ray-based travel-time inversion of the data, have shown that Vp in the uppermost mantle is 8.0-8.3 km/s. A 15-20 km thick layer (layer-H) with >6% seismic anisotropy (N-S V_P of 8.3 km/s and E-W V_P of 8.8 km/s) dips northward at ˜10^o from a minimum depth of 48-50 km. The attitude of layer-H is consistent with the general tectonic strike; its depth range (50-75 km) falls within that of the Hales discontinuity. If a link between the Hales discontinuity and layer-H can be drawn, observations strengthen the objection that the estimated velocity contrast (0.2 to 0.4 km/s depending on the direction of wave propagation) is relatively high if layer-H represents a phase transition, and thus (re)opens the debate on the nature of shallow upper-mantle boundaries beneath continents. The high V_P and intermediate anisotropy of upper-mantle layer-H requires a harzburgite peridotitic composition with the a-axis of olivine aligned E-W. Layer-H might have emplaced during accretion (2.7 Ga Kenoran orogeny) of the North American proto-craton and be relic oceanic lithosphere. The Hales discontinuity might be an expression of continents accretion and map relic slabs in the shallow upper mantle.

  13. A proteomic study on a human osteosarcoma cell line Saos-2 treated with diallyl trisulfide.

    PubMed

    Zhang, Yong Kui; Zhang, Xu Hua; Li, Jian Min; Sun, De Sheng; Yang, Qiang; Diao, Dong Mei

    2009-09-01

    Garlic is generally used as a therapeutic reagent against various diseases, and numerous studies have indicated that garlic and its derivatives can reduce the risk of various types of human cancer. Diallyl trisulfide (DATS), a major member of garlic derivatives, could inhibit the cell proliferation by triggering either cell cycle arrest or apoptosis in a variety of cancer cell lines as shown in many studies. However, whether DATS has the same effect on human osteosarcoma cells remains unknown. In this study, we have attempted to analyze the effects of DATS on cell proliferation, cell cycle, induction of apoptosis, global protein expression pattern in a human osteosarcoma cell line Saos-2 cells, and the potential molecular mechanisms of the action of DATS. Saos-2 cells, a human osteosarcoma cell line, were treated with or without 25, 50, and 100 micromol/l DATS for various time intervals. The cell proliferation, cell cycle progression, and apoptosis were examined in this study. Then, after treatment with or without 50 micromol/l DATS for 48 h, protein add pattern in Saos-2 cells were systematically studied using two-dimensional electrophoresis and mass spectrometry. DATS could inhibit the proliferation of Saos-2 cells in a dose-dependent and time-dependent manner. Moreover, the percentage of apoptotic cell and cell arrest in G0/G1 phase was also dose-dependent and time-dependent upon DATS treatment. A total of 27 unique proteins in Saos-2 cells, including 18 downregulated proteins and nine upregulated proteins, were detected with significant changes in their expression levels corresponding to DATS administration. Interestingly, almost half of these proteins (13 of 27) are related to either the cell cycle or apoptosis. DATS has the ability to suppress cell proliferation of Saos-2 cells by blocking cell cycle progression and inducing apoptosis in a dose and time-dependent manner. The proteomic results presented, therefore, provide additional support to the hypothesis

  14. The Early History of Psychoanalysis in San Francisco.

    PubMed

    Benveniste, Daniel

    2006-01-01

    The early history of psychoanalysis in San Francisco begins in 1918 and ends in 1953. During those 35 years the San Francisco Bay Area witnessed the awakening of interest in psychoanalysis, the arrival of the European émigré analysts and the emergence of individuals and groups engaging in extraordinarily creative work and doing so in an ecumenical spirit and with a social commitment. This article provides an overview of this illustrious history and the people who participated in it.

  15. Late-Archaean Potassic Granite from the Bundelkhand Craton, Central India

    NASA Astrophysics Data System (ADS)

    Sarkar, Saheli; Saha, Lopamudra; Nasipuri, Pritam; Pati, Jayanta Kumar; Patole, Vishal

    2014-05-01

    Late-Archaean granitoids, show wide range of compositional variation: (i) TTG like granitoids with strongly fractionated REE patterns, which can be both Na-rich and K-Mg-rich (Sanukitoids) (ii) K-rich, Mg-poor biotite granites with less fractionated REE patterns and showing negative Eu-anomalies (type area, the Closepet Granite, Eastern Dharwar Craton, India). Amongst them Late-Archaean Sanukitoid or K-rich Closepet-type granitoids are most widely reported from the Archaean Cratons world-wide: Superior Province, Canada, Pilbara Craton, Yilgarn Craton, Antarctica, Limpopo Belt, Dharwar Craton. Several models proposed so far for the origin of these granitoids mostly include partial melting of hydrated basalts, reaction of slab melts with mantle wedge peridotites, re-melting of an enriched mantle and then mixing of the resulting melt with the anatectic melt generated during the melting of continental crust in subduction zone settings. The Closepet-type potassic biotite-rich granites were mostly produced by re-melting of TTG-like continental basements most likely in a subduction zone setting. Most of the proposed models suggest such partial melting to have taken place in garnet-stability field and some in orthopyroxene-stability field. In this study we report late-Archaean (~2.61-2.5 Ga) potassic granite from the Bundelkhand Craton in central India. The Late-Archaean granitoids recorded from the craton are intrusive into the high-grade supracrustal rocks of the craton. They are classified as coarse grained grey, pink porphyritic granite, medium granied pink granite, granite porphyry and fine-grained pink granite. The supracrustal rocks of the craton have been metamorphosed at ~2.78 Ga under high-pressure conditions (~17-18 kbar)- medium temperature (600ºC) in a subduction zone setting. The intrusions of the granitoids at ~2.6-2.5 Ga mark the stability of the craton. The pink-porphyritic granite studied here preserves plagioclase-potash feldspar

  16. Sao Paulo Lightning Mapping Array (SP-LMA): Deployment, Operation and Initial Data Analysis

    NASA Technical Reports Server (NTRS)

    Blakeslee, R.; Bailey, J. C.; Carey, L. D.; Rudlosky, S.; Goodman, S. J.; Albrecht, R.; Morales, C. A.; Anseimo, E. M.; Pinto, O.

    2012-01-01

    An 8-10 station Lightning Mapping Array (LMA) network is being deployed in the vicinity of Sao Paulo to create the SP-LMA for total lightning measurements in association with the international CHUVA [Cloud processes of the main precipitation systems in Brazil: A contribution to cloud resolving modeling and to the GPM (Global Precipitation Measurement)] field campaign. Besides supporting CHUVA science/mission objectives and the Sao Luiz do Paraitinga intensive operation period (IOP) in November-December 2011, the SP-LMA will support the generation of unique proxy data for the Geostationary Lightning Mapper (GLM) and Advanced Baseline Imager (ABI), both sensors on the NOAA Geostationary Operational Environmental Satellite-R (GOES-R), presently under development and scheduled for a 2015 launch. The proxy data will be used to develop and validate operational algorithms so that they will be ready for use on "day1" following the launch of GOES-R. A preliminary survey of potential sites in the vicinity of Sao Paulo was conducted in December 2009 and January 2010, followed up by a detailed survey in July 2010, with initial network deployment scheduled for October 2010. However, due to a delay in the Sao Luiz do Paraitinga IOP, the SP-LMA will now be installed in July 2011 and operated for one year. Spacing between stations is on the order of 15-30 km, with the network "diameter" being on the order of 30-40 km, which provides good 3-D lightning mapping 150 km from the network center. Optionally, 1-3 additional stations may be deployed in the vicinity of Sao Jos dos Campos.

  17. 33 CFR 3.55-20 - Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Francisco Bay Marine Inspection Zone and Captain of the Port Zone. 3.55-20 Section 3.55-20 Navigation and..., MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Eleventh Coast Guard District § 3.55-20 Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone. The Sector San...

  18. 33 CFR 3.55-20 - Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Francisco Bay Marine Inspection Zone and Captain of the Port Zone. 3.55-20 Section 3.55-20 Navigation and..., MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Eleventh Coast Guard District § 3.55-20 Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone. The Sector San...

  19. 33 CFR 3.55-20 - Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Francisco Bay Marine Inspection Zone and Captain of the Port Zone. 3.55-20 Section 3.55-20 Navigation and..., MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Eleventh Coast Guard District § 3.55-20 Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone. The Sector San...

  20. 33 CFR 3.55-20 - Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Francisco Bay Marine Inspection Zone and Captain of the Port Zone. 3.55-20 Section 3.55-20 Navigation and..., MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Eleventh Coast Guard District § 3.55-20 Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone. The Sector San...

  1. 33 CFR 3.55-20 - Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Francisco Bay Marine Inspection Zone and Captain of the Port Zone. 3.55-20 Section 3.55-20 Navigation and..., MARINE INSPECTION ZONES, AND CAPTAIN OF THE PORT ZONES Eleventh Coast Guard District § 3.55-20 Sector San Francisco: San Francisco Bay Marine Inspection Zone and Captain of the Port Zone. The Sector San...

  2. Dynamic study of the upper Sao Francisco river and Tres Marias reservoir using MSS/LANDSAT images. M.S. Thesis; [BRazil

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Sausen, T. M.

    1981-01-01

    The relationship between the dispersion and concentration of sediment in the superficial layers of the Tres Marias reservoir and the dynamics of the drainage basins of its tributaries was verified using LANDSAT MSS imagery. The drainage network, dissection patterns, and land use of each watershed were considered in an analysis of multispectral images, corresponding to bands 4,5, and 7, of dry and rainy seasons in 1973, 1975, 1977, and 1978. The superficial layer water layers of the reservoir were also divided according to the grey level pattern of each image. Two field trips were made to collect Secchi depths and in situ water reflectance. It is concluded that it is possible to determine the main factors that act in the dynamics of the drainage basins of a reservoir by simultaneous control of the physical variables and the antropic action of each basin.

  3. Thermo-chemical structure of the North China Craton from multi-observable probabilistic inversion: extent and causes of cratonic lithosphere modification

    NASA Astrophysics Data System (ADS)

    Guo, Z.; Afonso, J. C.; Qashqai, M.; Yang, Y.; Chen, J.

    2016-12-01

    Although the North China Craton (NCC) is one of the best documented cases of cratonic lithosphere modification, the actual causes, processes, and extent of lithospheric modification still are a matter of debate. Here, we present the first thermo-chemical model of the NCC from the surface down to 350 km by jointly inverting surface wave phase velocity data, geoid height, surface heat flow and absolute elevation with a novel multi-observable probabilistic inversion method. Our model reveals a thin ( 65-100 km) and chemically fertile lithosphere (8790) lithospheric mantle is imaged beneath the central TNCO and Ordos Block, reaching depths > 260 km. This lithospheric "keel" is surrounded to the east by a high-temperature sublithospheric anomaly that originates at depths > 280 km. The spatial distribution of this anomaly and its correlation with the location of recent volcanism in the region suggest that the anomaly represents a deep mantle upwelling being diverted by the cratonic keel and spreading onto regions of shallow lithosphere. Our results indicate that the present-day thermochemical structure beneath the NCC is the result of a complex interaction between a large-scale return flow associated with the subduction of the Pacific slab and the shallow lithospheric structure.

  4. Benthic fluxes in San Francisco Bay

    USGS Publications Warehouse

    Hammond, Douglas E.; Fuller, C.; Harmon, D.; Hartman, Blayne; Korosec, M.; Miller, L.G.; Rea, R.; Warren, S.; Berelson, W.; Hager, S.W.

    1985-01-01

    Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (??1??) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2-3, 3, 4-5, and 3-10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m-2 d-1): O2 = -27 ?? 6; TCO2 = 23 ?? 6; Alkalinity = 9 ?? 2; N + N = -0.3 ?? 0.5; NH3 = 1.4 ?? 0.2; PO4 = 0.1 ?? 0.4; Si = 5.6 ?? 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal

  5. Surface and Moho topography as key constraints for understanding the thermo-rheological structure and longevity of cratons and tectons

    NASA Astrophysics Data System (ADS)

    Burov, E. B.; Francois, T.

    2013-12-01

    Surface topography and Moho are the most robust observables that have been insufficiently exploited for containing the rheological and thermal structure and hence for understanding the longevity and eventual destruction of cratons and 'tectons'. Craton longevity has been often explained by their buoyancy and analysed by testing gravitational stability of cratonic mantle 'keels' as a function of the hypothesized plate thickness and thermo-rheological structure. Destruction of some cratons (e.g. North China) and data indicating little if no buoyancy of some tectons (e.g., Arabian shield) suggest that buoyancy is not the only factor of their stability, and previous studies show that their mechanical strength is as important as buoyancy. The upper bounds on this strength are provided by flexural studies demonstrating that Te values (equivalent elastic thickness) in cratons are highest in the world and may probably reach 150 km. Yet, the sensitivity of common methods is poor for Te values above 80 km while the lower bounds on the strength and the equivalent elastic thickness of cratons are still matter of debate. How this strength is partitioned between crust and mantle, and which set of rheological parameters pertain, remain major unknowns. We show that smooth low topography and 'frozen' heterogeneous crustal structure of cratons represent the missing constraints for understanding of craton longevity. The cratonic crust is characterized by isostatically misbalanced density heterogeneities, suggesting that the lithosphere has to be strong enough to keep them 'frozen' through the time without producing major gravitational instabilities and topographic undulations. Hence, to constrain thermo-rheological properties of cratons one should first investigate the stability of their topography and internal structure (constrained from seismic and gravity data). Our thermo-mechanical numerical experiments accounting for free surface boundary condition demonstrate that craton

  6. Integrated Seismic Arrays for Imaging the North China Craton: the ¡°Destruction of the North China Craton¡± Project

    NASA Astrophysics Data System (ADS)

    Chen, Y. J.; Chen, L.; Zheng, T.; Zhou, S.

    2007-12-01

    It has been known, mostly according to the petrological and geochemical studies particularly the xenolith's data, that the North China craton (NCC), which is part of the Archaean Sino-Korean craton, had been reactivated since Mesozoic, and experienced widespread extension and volcanism through much of the Cenozoic. Currently the NCC is characterized by a thin lithosphere (as thin as 80 km according to published studies) and strong internal deformation, where over half of the eastern China's earthquakes occurred while the two major plate boundaries about China are thousands kilometers away. Although it is seismically quite active this region encompasses the China's capital and several mega cities which together hosts a large population and are very important to China's growing economy. Supported by the Chinese earth science community, the Chinese NSF recently started a major research program, the ¡°Destruction of the North China craton¡± (DNCC). About 150 million RMB (~ 20 million US dollars) will be allocated for this 5-year multi-disciplinary research program which is open for competition for all the earth scientists in China. Here we report one major seismic observation project of ¡°Integrated Seismic Arrays of DNCC¡± just funded during the first phase funding of DNCC. This observation-driven project integrates two groups at the Institute of Geology and Geophysics, Chinese Academy of Sciences and Peking University, and both institutions have their own broadband seismometers and have recently conducted pilot portable seismic array studies in North China. Up to seven linear broadband seismic arrays, each consists of 60-100 stations, are planned within the NCC. The principle objectives are to quantify the range and degree of the craton destruction in spatial domain with major focus on the east-west variation from the previously proposed intact craton in the west to the rejuvenated region in the east and the transition zone in the middle. With the expected

  7. Lithosphere structure underneath the North China Craton inferred from elevation, gravity and geoid anomalies

    NASA Astrophysics Data System (ADS)

    Wang, K.

    2015-12-01

    The North China Craton (NCC) is a classical example of ancient destroyed cratons. The NCC experienced widespread thermotectonic reactivations in the Phanerozoic. Recent work suggested that the old craton has been significantly modified or destroyed during this process. However, most of the studies were confined to the Eastern NCC, the nature and evolution of the lithosphere beneath the Central and Western NCC was less constrained due to the lack of data. While, recent geodetic data, with the advantages of high resolution and coverage, offers an opportunity to study the deep structure underneath the whole NCC. Here we construct a lithospheric-scale 3D model based on the integration of regional elevation, gravity, geoid and thermal data together with available seismic data. The combined interpretation of these data provides information on the density and temperature distribution at different depth ranges. In the Eastern NCC, a rapid thickness decrease of both crust and lithosphere is reflected, concordant with abrupt changes in surface topography and Bouguer gravity anomaly. Our results together with the widespread magmatic rocks suggest that the Eastern NCC has experienced significant destruction of the lithospheric mantle with substantial modifications and thinning of the crust. In the Central and Western NCC, the generally thick and 'cold' lithosphere suggests that the cratonic mantle root is preserved in the central and western NCC, in agreement with the relatively low heat flow, rare magmatic activity and long-term tectonic stability observed at the surface, with some areas mildly modified as indicated by thin lithosphere.

  8. Distribution of mineral deposits in accreted terranes and cratonal rocks of western United States.

    USGS Publications Warehouse

    Albers, J.P.

    1983-01-01

    The western margin of the USA, covering approx 777 000 km2, is an agglomeration of tectonostratigraphic terrains accreted to the North American craton mainly during Mesozoic time. The terrains represent a number of fundamental crustal types: oceanic crust, island-arc crust, melange, various combinations of the preceding three, batholithic, miogeoclinal and platform. The distribution patterns of types of mineral deposits show that miogeoclinal terrains of the craton are characterized by replacement and vein-type Pb-Zn-Ag, skarn W deposits, Mo and Sn, whereas accreted terrains contain all the known volcanic massive sulphide deposits, all chromite and chert-associated Mn, and all the large Au quartz-vein deposits, except Goldfield, Nevada. Carlin-type disseminated fine-grained Au deposits occur mostly in windows of Palaeozoic miogeoclinal rocks in Nevada, but the only known fine-grained Au deposit in California is in very youthful volcanic rocks overlying oceanic-crust terrain. Large bedded-type baryte deposits, although in the same area and showing the same trend as disseminated Au in Nevada, are in allochthonous oceanic terrain. Hg and Sb are dominantly in accreted terrains, but Sb also forms important deposits in cratonal rocks. Most of the large Fe deposits are in the craton, but a few are in accreted island-arc terrains.-P.Br.

  9. Geology of the Terre Adélie Craton (135 – 146˚ E)

    USGS Publications Warehouse

    Ménot, R.P.; Duclaux, G.; Peucat, J.J.; Rolland, Y.; Guillot, S.; Fanning, M.; Bascou, J.; Gapais, D.; Pêcher, A.

    2007-01-01

    More than 15 years of field and laboratory investigations on samples from Terre Adélie to the western part of George Vth Land (135 to 146°E) during the GEOLETA program allow a reassessment of the Terre Adélie Craton (TAC) geology. The TAC represents the largest exposed fragment of the East Antarctic Shield preserved from both Grenville and Ross tectono-metamorphic events. Therefore it corresponds to a well-preserved continental segment that developed from the Neoarchean to the Paleoproterozoic. Together with the Gawler Craton in South Australia, the TAC is considered as part of the Mawson continent, i.e. a striking piece of the Rodinia Supercontinent. However, this craton represents one of the less studied parts of the East Antarctic Shield. The three maps presented here clearly point out the extent of two distinct domains within the Terre Adélie Craton and suggest that the TAC was built up through a polyphased evolution during the Neoarchean-Siderian (c.a. 2.5Ga) and the Statherian (c.a. 1.7Ga) periods. These data support a complete re-assessment of the TAC geology and represent a valuable base for the understanding of global geodynamics changes during Paleoproterozoic times.

  10. An isotopic perspective on growth and differentiation of Proterozoic orogenic crust: From subduction magmatism to cratonization

    NASA Astrophysics Data System (ADS)

    Johnson, Simon P.; Korhonen, Fawna J.; Kirkland, Christopher L.; Cliff, John B.; Belousova, Elena A.; Sheppard, Stephen

    2017-01-01

    The in situ chemical differentiation of continental crust ultimately leads to the long-term stability of the continents. This process, more commonly known as 'cratonization', is driven by deep crustal melting with the transfer of those melts to shallower regions resulting in a strongly chemically stratified crust, with a refractory, dehydrated lower portion overlain by a complementary enriched upper portion. Since the lower to mid portions of continental crust are rarely exposed, investigation of the cratonization process must be through indirect methods. In this study we use in situ Hf and O isotope compositions of both magmatic and inherited zircons from several felsic magmatic suites in the Capricorn Orogen of Western Australia to highlight the differentiation history (i.e. cratonization) of this portion of late Archean to Proterozoic orogenic crust. The Capricorn Orogen shows a distinct tectonomagmatic history that evolves from an active continental margin through to intracratonic reworking, ultimately leading to thermally stable crust that responds similarly to the bounding Archean Pilbara and Yilgarn Cratons. The majority of magmatic zircons from the main magmatic cycles have Hf isotopic compositions that are generally more evolved than CHUR, forming vertical arrays that extend to moderately radiogenic compositions. Complimentary O isotope data, also show a significant variation in composition. However, combined, these data define not only the source components from which the magmas were derived, but also a range of physio-chemical processes that operated during magma transport and emplacement. These data also identify a previously unknown crustal reservoir in the Capricorn Orogen.

  11. Lithospheric architecture of the Slave craton, northwest Canada, as determined from an interdisciplinary 3-D model

    NASA Astrophysics Data System (ADS)

    Snyder, D. B.; Hillier, M. J.; Kjarsgaard, B. A.; de Kemp, E. A.; Craven, J. A.

    2014-05-01

    geologic structures characteristic of mantle lithosphere within cratons found in continent interiors are interpreted using geo-registered diverse data sets from the Slave craton of northwest Canada. We developed and applied a new method for mapping seismic discontinuities in three dimensions using multiyear observations at sparse, individual broadband receivers. New, fully 3-D conductivity models used all available magnetotelluric data. Discontinuity surfaces and conductivity models were geo-registered with previously published P-wave and surface-wave velocity models to confirm first-order structures such as a midlithosphere discontinuity. Our 3-D model to 400 km depth was calibrated by "drill hole" observations derived from xenolith suites extracted from kimberlites. A number of new structural discontinuities emerge from direct comparison of coregistered data sets and models. Importantly, we distinguish primary mantle layers from secondary features related to younger metasomatism. Subhorizontal Slave craton layers with tapered, wedge-shaped margins indicate construction of the craton core at 2.7 Ga by underthrusting and flat stacking of lithosphere. Mapping of conductivity and metasomatism in 3-D, the latter inferred via mineral recrystallization and resetting of isotopic ages in xenoliths, indicates overprinting of the primary layered structures. The observed distribution of relatively conductive mantle at 100-200 km depths is consistent with pervasive metasomatism; vertical "chimneys" reaching to crustal depths in locations where kimberlites erupted or where Au mineralization is known.

  12. Vulnerability Assessment of a Coastal Dune System at São Francisco do Sul Island, Santa Catarina, Brazil

    NASA Astrophysics Data System (ADS)

    Alquini, Fernanda; Bertoni, Duccio; Sarti, Giovanni; Ciccarelli, Daniela; Pozzebon, Alessandro; Ferreira de Melo Júnior, João Carlos; Voos Vieira, Celso

    2016-10-01

    In this paper a Coastal Dune Vulnerability Index (CDVI) has been applied on a beach located in the eastern side of Sao Francisco do Sul Island (Brazil). The aim of this study is to assess the vulnerability of a coastal dune system and to identify the areas that result most sensitive to environmental changes. The CDVI has been applied along six transects traced out on two sectors that have been selected based on dune characteristics: Zone A is characterized by well developed parabolic dunes, whereas Zone B is characterized by transverse dunes. The analysis involved 51 quantitative and qualitative variables, divided into five groups: geomorphological dune system condition, marine influence, Aeolian effect, vegetation condition and human effect. The total CDVI was computed as the unweighted average of the partial vulnerability indices. In summary, the total vulnerability can be classified as medium: the geomorphological factor must be monitored at Grande beach, in particular the blowouts in Zone A and the frontal dune retreat in Zone B. The results of the study confirm that the management of coastal areas might be improved using a tool such as the CDVI, which can be easily applied on a regular basis to take under control the factors that mostly affect the evolution of the site.

  13. Documentation for the machine-readable version of the SAO-HD-GC-DM cross index version 1983

    NASA Technical Reports Server (NTRS)

    Roman, N. G.; Warren, W. H., Jr.; Schofield, N., Jr.

    1983-01-01

    An updated and extended machine readable version of the Smithsonian Astrophysical Observatory star catalog (SAO) is described. A correction of all errors which were found since preparation of the original catalog which resulted from misidentifications and omissions of components in multiple star systems and missing Durchmusterung numbers (the common identifier) in the SAO Catalog are included and component identifications from the Index of Visual Double Stars (IDS) are appended to all multiple SAO entries with the same DM numbers, and lower case letter identifiers for supplemental BD stars are added. A total of 11,398 individual corrections and data additions is incorporated into the present version of the cross index.

  14. SAOS-2 osteosarcoma cells bind fibroblasts via ICAM-1 and this is increased by tumour necrosis factor-α.

    PubMed

    David, Manu S; Kelly, Elizabeth; Cheung, Ivan; Xaymardan, Munira; Moore, Malcolm A S; Zoellner, Hans

    2014-01-01

    We recently reported exchange of membrane and cytoplasmic markers between SAOS-2 osteosarcoma cells and human gingival fibroblasts (h-GF) without comparable exchange of nuclear markers, while similar h-GF exchange was seen for melanoma and ovarian carcinoma cells. This process of "cellular sipping" changes phenotype such that cells sharing markers of both SAOS-2 and h-GF have morphology intermediate to that of either cell population cultured alone, evidencing increased tumour cell diversity without genetic change. TNF-α increases cellular sipping between h-GF and SAOS-2, and we here study binding of SAOS-2 to TNF-α treated h-GF to determine if increased cellular sipping can be accounted for by cytokine stimulated SAOS-2 binding. More SAOS-2 bound h-GF pe-seeded wells than culture plastic alone (p<0.001), and this was increased by h-GF pre-treatment with TNF-α (p<0.001). TNF-α stimulated binding was dose dependent and maximal at 1.16 nM (p<0.05) with no activity below 0.006 nM. SAOS-2 binding to h-GF was independent of serum, while the lipopolysaccharide antagonist Polymyxin B did not affect results, and TNF-α activity was lost on boiling. h-GF binding of SAOS-2 started to increase after 30min TNF-α stimulation and was maximal by 1.5 hr pre-treatment (p<0.001). h-GF retained maximal binding up to 6 hrs after TNF-α stimulation, but this was lost by 18 hrs (p<0.001). FACS analysis demonstrated increased ICAM-1 consistent with the time course of SAOS-2 binding, while antibody against ICAM-1 inhibited SAOS-2 adhesion (p<0.04). Pre-treating SAOS-2 with TNF-α reduced h-GF binding to background levels (p<0.003), and this opposite effect to h-GF cytokine stimulation suggests that the history of cytokine exposure of malignant cells migrating across different microenvironments can influence subsequent interactions with fibroblasts. Since cytokine stimulated binding was comparable in magnitude to earlier reported TNF-α stimulated cellular sipping, we conclude that TNF

  15. SAOS-2 Osteosarcoma Cells Bind Fibroblasts via ICAM-1 and This Is Increased by Tumour Necrosis Factor-α

    PubMed Central

    David, Manu S.; Kelly, Elizabeth; Cheung, Ivan; Xaymardan, Munira; Moore, Malcolm A. S.; Zoellner, Hans

    2014-01-01

    We recently reported exchange of membrane and cytoplasmic markers between SAOS-2 osteosarcoma cells and human gingival fibroblasts (h-GF) without comparable exchange of nuclear markers, while similar h-GF exchange was seen for melanoma and ovarian carcinoma cells. This process of “cellular sipping” changes phenotype such that cells sharing markers of both SAOS-2 and h-GF have morphology intermediate to that of either cell population cultured alone, evidencing increased tumour cell diversity without genetic change. TNF-α increases cellular sipping between h-GF and SAOS-2, and we here study binding of SAOS-2 to TNF-α treated h-GF to determine if increased cellular sipping can be accounted for by cytokine stimulated SAOS-2 binding. More SAOS-2 bound h-GF pe-seeded wells than culture plastic alone (p<0.001), and this was increased by h-GF pre-treatment with TNF-α (p<0.001). TNF-α stimulated binding was dose dependent and maximal at 1.16nM (p<0.05) with no activity below 0.006 nM. SAOS-2 binding to h-GF was independent of serum, while the lipopolysaccharide antagonist Polymyxin B did not affect results, and TNF-α activity was lost on boiling. h-GF binding of SAOS-2 started to increase after 30min TNF-α stimulation and was maximal by 1.5hr pre-treatment (p<0.001). h-GF retained maximal binding up to 6hrs after TNF-α stimulation, but this was lost by 18hrs (p<0.001). FACS analysis demonstrated increased ICAM-1 consistent with the time course of SAOS-2 binding, while antibody against ICAM-1 inhibited SAOS-2 adhesion (p<0.04). Pre-treating SAOS-2 with TNF-α reduced h-GF binding to background levels (p<0.003), and this opposite effect to h-GF cytokine stimulation suggests that the history of cytokine exposure of malignant cells migrating across different microenvironments can influence subsequent interactions with fibroblasts. Since cytokine stimulated binding was comparable in magnitude to earlier reported TNF-α stimulated cellular sipping, we conclude that TNF

  16. Documentation for the machine-readable version of the Smithsonian Astrophysical Observatory Star catalogue (SAO) version 1984

    NASA Technical Reports Server (NTRS)

    Roman, N. G.; Warren, W. H., Jr.

    1984-01-01

    An updated, corrected and extended machine readable version of the Smithsonian Astrophysical Observatory star catalog (SAO) is described. Published and unpublished errors discovered in the previous version have been corrected, and multiple star and supplemental BD identifications added to stars where more than one SAO entry has the same Durchmusterung number. Henry Draper Extension (HDE) numbers have been added for stars found in both volumes of the extension. Data for duplicate SAO entries (those referring to the same star) have been blanked out, but the records themselves have been retained and flagged so that sequencing and record count are identical to the published catalog.

  17. Water and Metasomatism in the Slave Cratonic Lithosphere (Canada): An FTIR Study

    NASA Technical Reports Server (NTRS)

    Kilgore, McKensie; Peslier, Anne H.; Brandon, Alan D.; Schaffer, Lillian Aurora; Pearson, D. Graham; O'Reilly, Suzanne Yvette; Kopylova, Maya G.; Griffin, William L.

    2017-01-01

    Water in the mantle influences melting, viscosity, seismic velocity, and electrical conductivity. The role played by water in the long-term stabilization of cratonic roots is currently being debated. This study focuses on water contents of mantle minerals (olivine, pyroxene and garnet) from xenoliths found in kimberlites of the Archean Slave craton. 19 mantle xenoliths from central Lac de Gras, and 10 from northern Jericho were analyzed by FTIR for water, and their equilibration depths span the several compositional layers identified beneath the region. At both locations, the shallow peridotites have lower water contents in their olivines (11-30 ppm H2O) than those from the deeper layers (28-300 ppm H2O). The driest olivines, however, are not at the base of the cratonic lithosphere (>6 GPa) as in the Kaapvaal craton. Instead, the deepest olivines are hydrous (31-72 ppm H2O at Lac de Gras and 275 ppm H2O at Jericho). Correlations of water in clinopyroxene and garnet with their other trace element contents are consistent with water being added by metasomatism by melts resembling kimberlite precursors in the mantle approx.0.35 Ga ago beneath Lac de Gras. The northern Jericho xenoliths are derived from a region of the Slave craton that is even more chemically stratified, and was affected at depth by the 1.27 Ga Mackenzie igneous events. Metasomatism at Jericho may be responsible for the particularly high olivine water contents (up to 300 ppm H2O) compared to those at Lac de Gras, which will be investigated by acquiring trace-element data on these xenoliths. These data indicate that several episodes of metasomatic rehydration occurred in the deep part of the Slave craton mantle lithosphere, with the process being more intense in the northern part beneath Jericho, likely related to a translithospheric suture serving as a channel to introduce fluids and/or melts in the northern region. Consequently, rehydration of the lithosphere does not necessarily cause cratonic root

  18. Microxenoliths from the Slave craton: Archives of diamond formation along fluid conduits

    NASA Astrophysics Data System (ADS)

    Aulbach, Sonja; Stachel, Thomas; Heaman, Larry M.; Carlson, Jon A.

    2011-10-01

    A suite of 23 diamondiferous microxenoliths from the Ekati kimberlites in the central Slave craton was studied to elucidate the tectonothermal evolution of the lithosphere during craton formation and modification along craton margins, and associated diamond formation. Major- and trace-element abundances of eclogites (n = 16) reveal the presence of two compositionally distinct suites: a group of three eclogites with typical gabbroic trace-element patterns (flat REE N and low ΣREE, positive Sr N and Pb N, negative Zr N anomalies) and a group of 13 eclogites that are characterised by lower Mg#, Cr, Sc and Sr combined with higher Al 2O 3, TiO 2 and Na 2O, and a conspicuously stepped REE pattern with lower LREE/HREE. Inclusions in diamonds from the central Slave craton consistently plot with the latter group. The unusual trace-element characteristics of the second group are strikingly similar to those produced along fluid conduits in younger subduction zones, where infiltration of a metasomatic fluid induced eclogitisation. Eclogitic diamonds contain an average of 540 at.ppm nitrogen that is poorly aggregated (12% in the B centre), similar to eclogitic diamonds recovered from the A154 kimberlite (Diavik Mine, ~ 30 km southeast) that were dated to 1.85 Ga and linked to subduction at the western craton margin. This suggests that (1) by 1.85 Ga subduction-related reactive fluid transport and element mobilisation similar to younger examples were established, and (2) this fluid flow not only catalysed eclogitisation of subducting oceanic crust, but also was a prerequisite for the majority of eclogitic diamond formation beneath the central Slave craton. Harzburgitic and lherzolitic diamondiferous microxenoliths (n = 4) may document diamond formation in the Slave craton prior to emplacement of eclogites. Peridotitic garnets have sinusoidal REE-patterns with strong depletions in Ti, consistent with carbonate-melt or fluid metasomatism that may have also prompted diamond growth

  19. Environmental setting of San Francisco Bay

    USGS Publications Warehouse

    Conomos, T.J.; Smith, R.E.; Gartner, J.W.

    1985-01-01

    San Francisco Bay, the largest bay on the California coast, is a broad, shallow, turbid estuary comprising two geographically and hydrologically distinct subestuaries: the northern reach lying between the connection to the Pacific Ocean at the Golden Gate and the confluence of the Sacramento-San Joaquin River system, and the southern reach (herein called South Bay) between the Golden Gate and the southern terminus of the bay. The northern reach is a partially mixed estuary dominated by seasonally varying river inflow, and the South Bay is a tidally oscillating lagoon-type estuary. Freshwater inflows, highest during winter, generate strong estuarine circulation and largely determine water residence times. They also bring large volumes of dissolved and particulate materials to the estuary. Tidal currents, generated by mixed semidiurnal and diurnal tides, mix the water column and, together with river inflow and basin geometry, determine circulation patterns. Winds, which are strongest during summer and during winter storms, exert stress on the bay's water surface, thereby creating large waves that resuspend sediment from the shallow bay bottom and, together with the tidal currents, contribute markedly to the transport of water masses throughout the shallow estuary. ?? 1985 Dr W. Junk Publishers.

  20. The invisible hand in San Francisco.

    PubMed

    Adams, J; Bouvier, L; Davis, C; Gardner, B; Haupt, A; Kent, M; Molajo, D; Merrick, T; Scully, J; Van Der Tak, J

    1986-05-01

    Over 1000 population enthusiasts found their way to San Francisco for the 1986 meetings of the Population Association of America (PAA) April 3-5. 2 pre-meetings included: 1) the Association for Population/Family Planning Libraries and Information Centers-International (APLIC), and 2) the psychosocial workshop. Sexual activity was a major topic of the session on "Fertility: Early and Late." Further investigation of the effects of marriage and fertility on behavior was reviewed in a session entitled "Trends in Household Composition and Living Arrangements." The session "Demography of Crime and Justice" gave the demographic answer to such questions as: Is the crime rate really falling? Opinions in a panel on the future of US international population policy were sharply divided; Agency for International Development representative Alison Rosenberg outlined the re-examination of the Agency's population program that had taken place since the population conference in Mexico City in 1984. The Presidential Address was preceded by the annual awards ceremony. PAA President Paul Demeny focused on an issue that has been at the core of the debate about whether population has good, bad, indifferent, or indeterminate effects on economic development: the extent to which society can entrust the solution of population problems to market forces. This year's PAA meeting echoed growing concern in the population field about low fertility in the more developed world as well as increasing skepticism over the negative consequences of rapid developing country population growth.

  1. [Deafness and mentality in Francisco Goya's paintings].

    PubMed

    Betlejewski, Stanisław; Ossowski, Roman

    2009-01-01

    The famous painter Francisco Goya y Lucientes (1746-1828) suffered during his life one or several diseases, the nature of which has not been determined with certainty. At age of 46, Goya suffered from severe illness that lasted a few months. It caused loss of vision and hearing, tinnitus, dizziness, a right-sides paralysis, weakness and general malaise. Although he recovered from a cerebral stroke which accompanied it, the deafness remained unaltered. The illness divides Goya's artistic life into two great different periods. After in the painter produces his greatest works. The visual experience after the illness was heightened by the exclusion of acoustics stimuli and the artist's talent rose to the highest level. His character became more withdrawn and introspective and his entire vitality was direscted to his painting. Goya's painting became progressively more gloom and satirical during his long convalescence. The artist suffered a stroke at age 73 that again rendered him paralysed on the right side. The precise cause of his illness has long been debated. Ome medical writers have favored the diagnosis of syphilis, some consider the possibility of an exogenous psychosis, and other suggests that the symptoms of the illness are more congruent with heavy metal poisoning, particulary lead. It is interesting to speculate how the Goya's deafness influenced the artist's mentality and the changes of his painting. Interesting is also the problem of the sensory compensation in fact of disturbance of physiological function of one of the senses.

  2. [The five wills of Francisco Xavier Balmis].

    PubMed

    Tuells, José; Duro Torrijos, José Luis

    2012-01-01

    The recent discovery of the testamentary records of Francisco Xavier de Balmis (1753-1819), director of the Royal Philanthropic Expedition of the Vaccine, constitutes a new source material with which to study his biographical profile.Balmis wrote a total of five wills covering the period from 1803-1818 and coinciding with crucial moments in his life.The analysis of these documents has led to interesting observations that confirm Balmis’s personal insecurity before facing the Expedition, his vulnerability when he was stripped of his possessions for joining the royalist cause against Napoleon, the reassurance he felt when his honors and property were restored, or his fortitude in facing the final moments of his life. The documents also reveal that Balmis used his career as a military surgeon as a tool to achieve social prestige, and belie the assumptions of an obscure end. The inventory of his goods confirms his comfortable economic situation and his ability to manage it. The notarial sources are confirmed by this case of Balmis, an official of the Crown, as an appropriate source for the study of urban oligarchies of the Spanish Ancien Régime.

  3. The Río de la Plata craton and the assembly of SW Gondwana

    NASA Astrophysics Data System (ADS)

    Rapela, C. W.; Pankhurst, R. J.; Casquet, C.; Fanning, C. M.; Baldo, E. G.; González-Casado, J. M.; Galindo, C.; Dahlquist, J.

    2007-07-01

    The extent and nature of the Archaean-Palaeoproterozoic craton of Río de la Plata of southern South America, a major but poorly understood crustal component in Neoproterozoic plate reconstructions, as well as the depositional, metamorphic and magmatic history of the surrounding orogenic belts, are reviewed and reassessed, in part through the analysis of material recovered from deep boreholes in western Argentina that penetrated Palaeozoic cover into basement. U-Pb SHRIMP zircon ages for these samples of 2162 ± 6 Ma (diorite), 2189 ± 14 Ma (amphibolitic schist) and 2088 ± 6 Ma (granite) encompass the range of ages determined for the major Palaeoproterozoic orogenic events in the exposed parts of the craton close to the Atlantic coasts of Uruguay and Argentina. Taken together with the geochemical and Nd-isotope characteristics of these samples and an olivine gabbro from a further borehole that failed to yield zircon, these results strongly suggest that the Río de la Plata craton is extremely uniform in its dominant chrono-tectonic and lithological make-up, and that it extends westwards as far as the 535-520 Ma Pampean orogenic belt, against which it probably has a fault contact. U-Pb SHRIMP zircon detrital age patterns are presented for representative metasedimentary samples from the craton cover in the Tandilia belt of eastern Argentina, and from the Pampean (Cambrian) and Famatinian (Ordovician) belts to the west of the craton. Whereas the oldest cover rocks in Tandilia clearly show material derived from the underlying craton, such detritus only appears in the younger (Ordovician) units to the west. Sedimentary protoliths in the Pampean belt were dominated by Neoproterozoic (broadly ˜ 600 Ma) and late Mesoproterozoic (broadly ˜ 1100 Ma) provenance, and derivation from the Río de la Plata craton is highly unlikely. Regional considerations, including previously published zircon data, palaeocurrent and structural data, suggest that these rocks must have had an

  4. Exploring the decoupling and removal of dense material during lithospheric thickening as applicable to craton formation

    NASA Astrophysics Data System (ADS)

    Wood, R. J.; Cooper, C. M.

    2013-12-01

    Cratons are areas of continental crust and lithosphere that have not deformed for billions of years; thus, comprising the most stable regions on the Earth's surface. However, the processes that lead to craton formation introduce potential instabilities. For example, cratons formed via the stacking of buoyant oceanic lithosphere would pose some potentially serious buoyancy complications as the basaltic crust tends to transform into much denser eclogite at depth. Thus, if basaltic crust is a significant portion of buoyant oceanic lithosphere, the entire thickened package could be overwhelmed by the transition to eclogite. This could in turn promote instability, foundering and failure to produce thick cratonic lithosphere. Alternatively, forming thick cratonic lithosphere via the amalgamation of arc or continental material would also introduce instability. Achieving the required integrated buoyancy from island arc material also requires a secondary removal process of mafic/ultramafic cumulates during collision. This leads to several testable questions; how much dense material can the system maintain before becoming unstable? Does the relative depth of the dense material effect stability? Does the dense material needs to be removed or can it be modified in some manner to maintain stability? If it can be modified, which process or processes can do so? We will present numerical models exploring one such modification process- the decoupling and removal of dense material during lithospheric thickening. We have expanded our lithospheric convection models to include 3x1 and 5x1 dimensions and wrap-around boundary conditions. Additionally, we have also calculated the isopycnicity of the thickened lithospheric material in our simulations to determine whether stability can be achieved even if not all of the dense material has been removed.

  5. Neoproterozoic-Early Paleozoic rifting of the craton margin in eastern Kentucky: Evidence from subsidence analysis

    SciTech Connect

    Goodman, P.T. . Dept. of Geological Sciences); Walker, D. )

    1992-01-01

    Analysis of subsidence along the craton margin in eastern Kentucky indicates a Neoproterozoic to Early through Middle Cambrian rifting event developing on a subsiding passive margin of the Laurentian craton to the Iapetus Ocean. Subsidence associated with rifting is confined to the Rome Trough; an internally broken half-graben within the Laurentian craton; the trough trends sub-parallel to the Appalachian orogenic belt. In cross section the through as an abrupt faulted margin on the carton side and a tapering, gentle extension toward the orogenic belt. The stratigraphic sequence within the Rome Trough and toward the orogen consists of Neoproterozoic or early Cambrian basal sands overlying Grenville basement, and succeeded by silts, shales and discontinuous carbonates of the Rome Fm. that are overlain by shales and carbonates of the Conesauga Fm. Stratigraphic relationships suggest that an out-of-sequence, inboard rift developed along the Laurentian margin adjacent to a drift-phase continental shelf represented by strata of the Blue Ridge and Valley and Ridge. Analysis of the subsidence history of this region reveals trends which support the notion that the subsidence history of this area cannot be accounted for by typical passive-margin development. The subsidence history of the area within the Rome Trough presents a pattern of high thermal subsidence and produces beta values greater than in areas nearer the craton margin. These data indicate that an inboard locus of anomalous crustal extension occurred in the area of the Rome Trough while the remainder of the cratonal margin underwent drift-phase subsidence, and that the timing and magnitude of this event is related to the development of the Iapetan margin.

  6. Multiscale finite-frequency Rayleigh wave tomography of the Kaapvaal craton

    NASA Astrophysics Data System (ADS)

    Chevrot, S.; Zhao, L.

    2007-04-01

    We have measured phase delays of fundamental-mode Rayleigh waves for 12 events recorded by the Southern Africa Seismic Experiment at frequencies between 0.005 and 0.035 Hz. A novel multiscale finite-frequency tomographic method based on wavelet decomposition of 3-D sensitivity kernels for the phase of Rayleigh waves is used to map the shear velocities in the upper mantle beneath southern Africa. The kernels are computed by summing coupled normal modes over a very fine grid surrounding the seismic array. To estimate and minimize the biases in the model resulting from structures outside the tomographic grid, a jackknife inversion method is implemented. The contribution of heterogeneities outside the target volume is significant, but produces artefacts in the tomographic model that are easily identified and discarded before interpretation. With structures on length scales as short as 100 km retrieved beneath the array, the deep structure of the Kaapvaal craton is revealed with unprecedented detail. Outside the array, the corresponding resolution is 200 km. High velocity cratonic roots are confined to the Archean craton, and extend to depths of at least 250 km. Confirming earlier surface structural studies, we recognize two distinct units in the Kaapvaal craton. The eastern Witwatersrand block and the western Kimberley block are separated by a major near-vertical translithospheric boundary which coincides with the Colesberg Lineament. Lower than average velocities south and east of the Kaapvaal craton reveal extensive metasomatism and heating of the lithosphere, probably related to the Karoo magmatic event and to the opening of the South Atlantic Ocean.

  7. Craton Development and Stabilization: Insights from SE Canada using P and S Wave Tomography

    NASA Astrophysics Data System (ADS)

    Boyce, A.; Bastow, I. D.; Darbyshire, F. A.; Gilligan, A.; Ellwood, A.; Levin, V. L.; Menke, W. H.

    2015-12-01

    Cratons, the ancient cores of the continents, are the longest-lived parts of Earth's surface that have survived thermal and mechanical erosion during multiple Wilson cycles. They are visible in tomographic images due to their thick (>200km), seismically fast keels or roots. The Laurentian keel beneath North America is intriguing since its root is thought to extend beneath both the Archean Superior craton and the Proterozoic Grenville province thus implying that keel formation may not have been restricted to Archean times. In order to address this issue we present a P and S wave relative arrival-time tomographic study using data from seismograph networks in SE Canada and the NE US, stretching from the southern tip of Hudson Bay within the Superior craton to the coastal Phanerozoic Appalachian terranes. The tomographic images display three broad zones of increasing mantle wavespeed from globally "slow" in the Appalachian terranes, to a "fast" Grenville Province and "extremely fast" Superior craton. We observe a linear low-velocity feature resulting from modification of the Laurentian keel by the passage of the Great Meteor hotspot. This feature is progressively offset southwestward with depth, potentially due to viscous coupling with mantle flow. No major plate-scale underthrusting during the Grenville Orogeny is apparent, which contradicts the inferred results from crustal seismic reflection and refraction studies. Our results therefore may have fundamental implications for the nature of the Grenville orogenic collision and cratonic stabilization of North America. The results also support the developing consensus that keels form in two stages: a chemically depleted core of Archean age followed by a thermally developed, less-depleted lithosphere during Proterozoic times, highlighted by an abrupt wavespeed contrast in the tomographic images.

  8. A preliminary assessment of metal bioaccumulation in the blue crab, Callinectes danae S., from the Sao Vicente Channel, Sao Paulo State, Brazil.

    PubMed

    Bordon, Isabella C A C; Sarkis, Jorge E S; Tomás, Acácio R G; Souza, Marcelo R; Scalco, Allan; Lima, Mariana; Hortellani, Marcos A

    2012-04-01

    The concentrations of metals in tissues of Callinectes danae were evaluated, aiming to determine the bioaccumulation process of this species. Gills presented the highest mean concentrations for most metals, except for Hg (Sao Vicente Channel is included) would be important to confirm if this pattern of bioaccumulation can be extended to the population of C. danae of this estuary.

  9. Hydrogen peroxide overload increases adriamycin-induced apoptosis of SaOS(2)FM, a manganese superoxide dismutase-overexpressing human osteosarcoma cell line.

    PubMed

    Wang, Yadi; Kuroda, Masahiro; Gao, Xian-Shu; Asaumi, Jun-Ichi; Shibuya, Kohichi; Kawasaki, Shoji; Akaki, Shiro; St Clair, Daret; Hiraki, Yoshio; Kanazawa, Susumu

    2005-05-01

    We previously developed a new microscopic observation system that enables time-lapse quantitative analysis of apoptosis and necrosis. With this system we quantitatively analyzed adriamycin (ADR)-induced cell death using manganese superoxide dismutase (MnSOD)- and wild-type p53-gene transfectants on SaOS(2), a p53-deficient human osteosarcoma cell line. A highly MnSOD-overexpressing cell line, SaOS(2)FM(H), acquired ADR-tolerance compared to the parent cell line SaOS(2). The ADR-tolerance of SaOS(2)FM(H) diminished by L-buthionine-[S,R]-sulfoximine (BSO), which did not change ADR-sensitivity of SaOS(2), to the similar ADR-sensitivity of SaOS(2). A wild-type p53-expressing cell line, SaOS(2)wtp53, significantly increased in ADR-sensitivity compared to SaOS(2). This ADR-sensitivity of SaOS(2)wtp53 was enhanced by BSO. When isosorbide 5-mononitrate was combined with BSO, isosorbide 5-mononitrate increased ADR sensitivity of a moderately MnSOD-overexpressing cell line, SaOS(2)FM(L), decreased that of SaOS(2) FM(H), and did not change those of SaOS(2) and SaOS(2)wtp53 compared to BSO alone. Time-lapse microscopic observations during ADR treatment for 24 h indicated that the most cells of each cell line underwent apoptosis, and a few cells (less than 11%) died by necrosis. When cells were treated with iso-concentration of ADR, apoptosis of SaOS(2)FM(H) was less than that of SaOS(2). BSO, which did not change ADR-sensitivity of SaOS(2), increased appearance rate of ADR-induced apoptosis, but not necrosis of MnSOD-overexpressing cell lines. When iso-survival dose of ADR, which reduced surviving fraction to 0.01, was given for each cell line, no difference was observed in appearance of either apoptosis or necrosis between SaOS(2) and MnSOD-overexpressing cell lines. On the other hands, appearance of both apoptosis and the following secondary necrosis of SaOS(2) wtp53 was significantly accelerated compared to those of SaOS(2). These findings indicate that hydrogen peroxide

  10. Breeding avifauna of the south San Francisco Bay estuary

    USGS Publications Warehouse

    Gill, Robert E.

    1977-01-01

    San Francisco Bay represents one of the largest estuarine areas on the Pacific Coast of North America. Its open waters, tidal flats, tidal marshes and solar evaporation ponds provide critical foraging, resting and breeding habitat for migratory and resident birds. The avifauna of San Francisco Bay has received considerable attention; however, little of it has been directed toward assessing the overall importance of the Bay as a nesting area. Works by Grinnell and Wythe (1927), Grinnell and Miller (1944) and Sibley (1952) are the only comprehensive studies of San Francisco Bay avifauna. These studies, while major contributions, are broad in scope as they relate to the breeding avifauna of the Bay's estuarine areas. Several studies by Johnston (1955, 1956a, b), Marshall (1948a, b), DeGroot (1927, 1931) and Zucca (1954) have concentrated on the breeding biology of individual species; however, much of the marsh reclamation and Bay fill has occurred since. The present breeding status of many resident and migratory birds is poorly known for San Francisco Bay. Included among these are three rare or endangered forms: California Black Rail, California Clapper Rail and California Least Tern. In addition, some species now found in the area represent recent breeding range extensions. This study, undertaken from March to September 1971 and including a few more recent data, presents a quantitative assessment of the present breeding bird populations in the South San Francisco Bay area.

  11. ASTER Images San Francisco Bay Area

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These images of the San Francisco Bay region were acquired on March 3, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. Each covers an area 60 kilometers (37 miles) wide and 75 kilometers (47 miles) long. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image the Earth for the next 6 years to map and monitor the changing surface of our planet.

    Upper Left: The color infrared composite uses bands in the visible and reflected infrared. Vegetation is red, urban areas are gray; sediment in the bays shows up as lighter shades of blue. Thanks to the 15 meter (50-foot) spatial resolution, shadows of the towers along the Bay Bridge can be seen.

    Upper right: A composite of bands in the short wave infrared displays differences in soils and rocks in the mountainous areas. Even though these regions appear entirely vegetated in the visible, enough surface shows through openings in the vegetation to allow the ground to be imaged.

    Lower left: This composite of multispectral thermal bands shows differences in urban materials in varying colors. Separation of materials is due to differences in thermal emission properties, analogous to colors in the visible.

    Lower right: This is a color coded temperature image of water temperature, derived from the thermal bands. Warm waters are in white and yellow, colder waters are blue. Suisun Bay in the upper right is fed directly from the cold Sacramento River. As the water flows through San Pablo and San Francisco Bays on the way to the Pacific, the waters warm up.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is

  12. Community Heavy Metal Exposure, San Francisco, California

    NASA Astrophysics Data System (ADS)

    Chavez, A.; Devine, M.; Ho, T.; Zapata, I.; Bissell, M.; Neiss, J.

    2008-12-01

    Heavy metals are natural elements that generally occur in minute concentrations in the earth's crust. While some of these elements, in small quantities, are vital to life, most are harmful in larger doses. Various industrial and agricultural processes can result in dangerously high concentrations of heavy metals in our environment. Consequently, humans can be exposed to unsafe levels of these elements via the air we breathe, the water and food we consume, and the many products we use. During a two week study we collected numerous samples of sediments, water, food, and household items from around the San Francisco Bay Area that represent industrial, agricultural, and urban/residential settings. We analyzed these samples for Mercury (Hg), Lead (Pb), and Arsenic (As). Our goal was to examine the extent of our exposure to heavy metals in our daily lives. We discovered that many of the common foods and materials in our lives have become contaminated with unhealthy concentrations of these metals. Of our food samples, many exceeded the EPA's Maximum Contaminant Levels (MCL) set for each metal. Meats (fish, chicken, and beef) had higher amounts of each metal than did non-meat items. Heavy metals were also prevalent in varying concentrations in the environment. While many of our samples exceeded the EPA's Sediment Screening Level (SSL) for As, only two other samples surpassed the SSL set for Pb, and zero of our samples exceeded the SSL for Hg. Because of the serious health effects that can result from over-exposure to heavy metals, the information obtained in this study should be used to influence our future dietary and recreational habits.

  13. [The teaching of Dr. Francisco Romero Aguirre].

    PubMed

    Pérez Albacete, Mariano; Romero Fernández, Francisco

    2007-10-01

    After the death of Professor Francisco Romero Aguirre (Zaragoza 6/7/1918-6/28/2006) we want to make known his great teaching vocation, so that we covered his link with University from the start of his studies to his professorship as first professor in urology in the Spanish University (1961), and his work at the chairmanship of the Professional Postgraduate School of Urology in the University of Zaragoza. We reviewed his biography, his edited works and publications of the Urology Chair at the University of Zaragoza, and obtained as many references as we found about his teaching activity. From the start of his academic training he kept a constant union with University and cooperated in all disciplines he had relation with before he got the responsibility of teaching urology. His university spirit and great formation had the chairman of surgical pathology see the convenience of separating urology from the common trunk of surgery, a proposal that, being accepted by the staff meeting of the Faculty of Medicine of Zaragoza and submitted to the Ministry resulted in the designation of urology as an independent subject in the degree of medicine. His labour as responsible was marked by work and continuous achievements in his classes, many publications, doctorate and urological monographic courses carried out, thesis and memories directed, all of which enabled him to create to the Professional Urological Specialization School, the culmination of more than 40 years dedicated to teaching in the university. We find Prof. Romero's life completely dedicated to University and teaching. His wide urological and propedeutical formation made him a person who joined the necessary conditions and abilities to take the responsibility and carry out a satisfactory performance as responsible of teaching urology in the school of medicine of Zaragoza, a subject which thanks to his virtue and good performance was for the first time elevated to the level of independent subject.

  14. Sex worker health: San Francisco style.

    PubMed

    Cohan, D; Lutnick, A; Davidson, P; Cloniger, C; Herlyn, A; Breyer, J; Cobaugh, C; Wilson, D; Klausner, J

    2006-10-01

    To describe the characteristics of sex workers accessing care at a peer based clinic in San Francisco and to evaluate predictors of sexually transmitted infections (STI). We conducted an observational study of sex workers at St James Infirmary. Individuals underwent an initial questionnaire, and we offered screening for STI at each clinic visit. We performed univariate, bivariate, and multivariable analyses to assess for predictors of STI in this population. We saw 783 sex workers identifying as female (53.6%), male (23.9%), male to female transgender (16.1%), and other (6.5%). 70% had never disclosed their sex work to a medical provider. Participants represented a wide range of ethnicities, educational backgrounds, and types of sex work. The most common substance used was tobacco (45.8%). Nearly 40% reported current illicit drug use. Over half reported domestic violence, and 36.0% reported sex work related violence. Those screened had gonorrhoea (12.4%), chlamydia (6.8%), syphilis (1.8%), or herpes simplex virus 2 (34.3%). Predictors of STI included African-American race (odds ratio (OR) 3.3), male gender (OR 1.9), and sex work related violence (OR 1.9). In contrast, participants who had only ever engaged in collective sex work were less likely to have an STI (OR 0.4). The majority of sex workers have never discussed their work with a medical provider. Domestic violence is extremely prevalent as is work related violence. Working with other sex workers appears to be protective of STIs. STI prevention interventions should target African-American and male sex workers. Addressing violence in the workplace and encouraging sex workers to work collectively may be effective prevention strategies.

  15. Sex worker health: San Francisco style

    PubMed Central

    Cohan, D; Lutnick, A; Davidson, P; Cloniger, C; Herlyn, A; Breyer, J; Cobaugh, C; Wilson, D; Klausner, J

    2006-01-01

    Objectives To describe the characteristics of sex workers accessing care at a peer based clinic in San Francisco and to evaluate predictors of sexually transmitted infections (STI). Methods We conducted an observational study of sex workers at St James Infirmary. Individuals underwent an initial questionnaire, and we offered screening for STI at each clinic visit. We performed univariate, bivariate, and multivariable analyses to assess for predictors of STI in this population. Results We saw 783 sex workers identifying as female (53.6%), male (23.9%), male to female transgender (16.1%), and other (6.5%). 70% had never disclosed their sex work to a medical provider. Participants represented a wide range of ethnicities, educational backgrounds, and types of sex work. The most common substance used was tobacco (45.8%). Nearly 40% reported current illicit drug use. Over half reported domestic violence, and 36.0% reported sex work related violence. Those screened had gonorrhoea (12.4%), chlamydia (6.8%), syphilis (1.8%), or herpes simplex virus 2 (34.3%). Predictors of STI included African‐American race (odds ratio (OR) 3.3), male gender (OR 1.9), and sex work related violence (OR 1.9). In contrast, participants who had only ever engaged in collective sex work were less likely to have an STI (OR 0.4). Conclusions The majority of sex workers have never discussed their work with a medical provider. Domestic violence is extremely prevalent as is work related violence. Working with other sex workers appears to be protective of STIs. STI prevention interventions should target African‐American and male sex workers. Addressing violence in the workplace and encouraging sex workers to work collectively may be effective prevention strategies. PMID:16854996

  16. Nucleus deformation of SaOs-2 cells on rhombic µ-pillars.

    PubMed

    Eichhorn, Melanie; Stannard, Cleo; Anselme, Karine; Rühe, Jürgen

    2015-02-01

    It has been previously shown that osteosarcoma (SaOs-2) cells respond to micropillared surfaces consisting of poly-L-lactic acid with strong deformation of the cell body and nucleus. Until now, cell nucleus deformation of SaOs-2 cells was only studied by exposing them to square shaped micropillars in an isotropic pattern. Here we report on experiments of the cell nucleus response of such cells to rhombic structures of different topographies generated from a rubbery polymer, namely poly(n-butyacrylate). It is observed that cells orientate themselves perpendicular to the long axis of the rhombi. While their spreading on the surface is not influenced by the opening angle of the structures, rhombic structures with sharper angles induce stronger deformation of the cells and accordingly more elongated nuclei.

  17. The contribution of bats to leptospirosis transmission in Sao Paulo City, Brazil.

    PubMed

    Bessa, Thirsa Alvares Franco; Spichler, Anne; Chapola, Erica G Berardis; Husch, Alfred Christian; de Almeida, Marilene Fernandes; Sodré, Miriam Martos; Savani, Elisa S M Mouriz; Sacramento, Débora R Veiga; Vinetz, Joseph M

    2010-02-01

    The biodiversity of potential leptospiral reservoir hosts is lower in urban than in rural environments. Previous data indicate the potential for bats to act as carriers of Leptospira in regions such as the Amazon of South America and in Australia. Yet, little is known about the contribution of bats to leptospirosis in urban environments in South America. This study aimed to test the hypothesis that bats infected with Leptospira are sources of leptospirosis transmission to humans in São Paulo City, Brazil. Six of 343 bats caught in different districts within the city of Sao Paulo (182 insectivorous, 161 frugivorous or nectarivorous) were polymerase chain reaction (PCR) positive for pathogenic Leptospira; no seropositive bats were found. That few renal carriers of Leptospira were found in the city of Sao Paulo suggests that bats are not important in the transmission of leptospirosis to humans in this, and possibly other urban settings.

  18. Radiocarbon dates for lava flows and pyroclastic deposits on Sao Miguel, Azores

    USGS Publications Warehouse

    Moore, R.B.; Rubin, M.

    1991-01-01

    We report 63 new radiocarbon analyses of samples from Sao Miguel, the largest island in the Azores archipelago. The samples are mainly carbonized tree roots and other plant material collected from beneath 20 mafic lava flows and spatter deposits and from within and beneath 42 trachytic pyroclastic flow, pyroclastic surge, mudflow, pumice-fall and lacustrine deposits and lava flows. One calcite date is reported. These dates establish ages for 48 previously undated lava flows and pyroclastic deposits, and revise three ages previously reported. These data are critical to deciphering the Holocene and late Pleistocene eruptive history of Sao Miguel and evaluating its potential volcanic hazards. Average dormant intervals during the past 3000 years are about 400 years for Sete Cidades volcano, 145 years for volcanic Zone 2, 1150 years for Agua de Pau volcano and 320 years for Furnas volcano. No known eruptions have occurred in volcanic Zone 4 during the past 3000 years. -from Authors

  19. SAO mission support software and data standards, version 1.0

    NASA Technical Reports Server (NTRS)

    Hsieh, P.

    1993-01-01

    This document defines the software developed by the SAO AXAF Mission Support (MS) Program and defines standards for the software development process and control of data products generated by the software. The SAO MS is tasked to develop and use software to perform a variety of functions in support of the AXAF mission. Software is developed by software engineers and scientists, and commercial off-the-shelf (COTS) software is used either directly or customized through the use of scripts to implement analysis procedures. Software controls real-time laboratory instruments, performs data archiving, displays data, and generates model predictions. Much software is used in the analysis of data to generate data products that are required by the AXAF project, for example, on-orbit mirror performance predictions or detailed characterization of the mirror reflection performance with energy.

  20. Phenotypic instability of Saos-2 cells in long-term culture

    SciTech Connect

    Hausser, Heinz-Juergen . E-mail: heinz-juergen.hausser@medizin.uni-ulm.de; Brenner, Rolf E.

    2005-07-22

    The human osteosarcoma cell line Saos-2 is widely used as a model system for human osteoblastic cells, though its phenotypic stability has not been ascertained. We therefore propagated these cells over 100 passages and compared relevant phenotypic properties. In general, higher passage cells exhibited higher proliferation rates and lower specific alkaline phosphatase activities, though mineralization was significantly more pronounced in cultures of late passage cells. Whereas expression of most genes investigated did not vary profoundly, some genes exhibited remarkable differences. Decorin, for instance, that has been discussed as a regulator of proliferation and mineralization, is strongly expressed only in early passage cells, and two receptors for pleiotrophin and midkine exhibited an almost mutually exclusive expression pattern in early and late passage cells, respectively. Our observations indicate that special care is required when results obtained with Saos-2 cells with different culture history are to be compared.

  1. Geologic mapping of the Bauru Group in Sao Paulo state by LANDSAT images. [Brazil

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Godoy, A. M.

    1983-01-01

    The occurrence of the Bauru Group in Sao Paulo State was studied, with emphasis on the western plateau. Regional geological mapping was carried out on a 1:250.000 scale with the help of MSS/LANDSAT images. The visual interpretation of images consisted basically of identifying different spectral characteristics of the geological units using channels 5 and 7. Complementary studies were made for treatment of data with an Interative Image (I-100) analyser in order to facilitate the extraction of information, particularly for areas where visual interpretation proved to be difficult. Regional characteristics provided by MSS/LANDSAT images, coupled with lithostratigraphic studies carried out in the areas of occurrence of Bauru Group sediments, enabled the homogenization of criteria for the subdivision of this group. A spatial distribution of the mapped units was obtained for the entire State of Sao Paulo and results were correlated with proposed stratigraphic divisions.

  2. Collagen with simvastatin promotes cell metabolism in osteoblast-like SaOS-2 cells.

    PubMed

    Suthanthiran, Thanga Kumaran; Elavarasu, Sugumari; Naveen, Devisree; Nagarathinam, Umamaheswari; Arun, K V; Srinivasan, N

    2012-08-01

    Simvastatin (SMV) is one of the cholesterol-lowering pharmacological drugs. Recent studies demonstrate that it has a bone stimulatory effect. The present study was designed to investigate the effect of SMV along with collagen membrane on osteoblast-like SaOS-2 cells and also to standardize the dosage of SMV to be incorporated into the collagen membrane to achieve regeneration. SMV at doses of 0.5, 1, 1.5, and 2 mg was incorporated into the collagen membrane and cell metabolism was assessed by (3-[4,5-dimethylthiazolyl-2]-2,5-diphenyltetrazolium bromide) (MTT) assay for 24 h. SMV enhanced cell metabolism dose dependently at 24-h time and the maximum effect was obtained at a concentration of 1.5 mg of SMV. These results indicate that collagen with 1.5 mg SMV exhibits positive effect on cell metabolism of human osteoblast-like SaOS-2 cells.

  3. p27kip1 overexpression promotes paclitaxel-induced apoptosis in pRb-defective SaOs-2 cells.

    PubMed

    Gabellini, Chiara; Pucci, Bruna; Valdivieso, Paola; D'Andrilli, Giuseppina; Tafani, Marco; De Luca, Antonio; Masciullo, Valeria

    2006-08-15

    p27kip1 is a cyclin-dependent kinase (CDK) inhibitor, which controls several cellular processes in strict collaboration with pRb. We evaluated the role of p27kip1 in paclitaxel-induced apoptosis in the pRb-defective SaOs-2 cells. Following 48 h of exposure of SaOs-2 cells to 100 nM paclitaxel, we observed an increase in p27kip1 expression caused by the decrease of the ubiquitin-proteasome activity. Such increase was not observed in SaOs-2 cells treated with the caspase inhibitors Z-VAD-FMK, suggesting that p27kip1 enhancement at 48 h is strictly related to apoptosis. Finally, we demonstrated that SaOs-2 cells transiently overexpressing the p27kip1 protein are more susceptible to paclitaxel-induced apoptosis than SaOs-2 cells transiently transfected with the empty vector. Indeed, after 48 h of paclitaxel treatment, 41.8% of SaOs-2 cells transiently transfected with a pcDNA3-p27kip1 construct were Annexin V-positive compared to 30.6% of SaOs-2 cells transfected with the empty vector (P < 0.05). In conclusion, we demonstrated that transfection of the pRb-defective SaOs-2 cells with the p27kip1 gene via plasmid increases their susceptibility to paclitaxel-induced apoptosis. The promoting effect of p27kip1 overexpression on apoptosis makes p27kip1 and proteasomal inhibitors interesting tools for therapy in patients with pRb-defective cancers. (c) 2006 Wiley-Liss, Inc.

  4. Different titanium surfaces modulate the bone phenotype of SaOS-2 osteoblast-like cells.

    PubMed

    Postiglione, L; Di Domenico, G; Ramaglia, L; di Lauro, A E; Di Meglio, F; Montagnani, S

    2004-01-01

    Commercially pure titanium implants presenting a relatively smooth, machined surface or a roughened endosseous surface show a large percentage of clinical success. Surface properties of dental implants seem to affect bone cells response. Implant topography appears to modulate cell growth and differentiation of osteoblasts affecting the bone healing around the titanium implant. The aim of the present study was to examine the effects of 1cm diameter and 1mm thick titanium disks on cellular morphology, adhesion and bone phenotypic expression of human osteoblast-like cells, SaOS-2. SaOS-2 cells were cultured on commercially 1 cm pure titanium disks with three different surface roughness: smooth (S), sandblasted (SB) and titanium plasma sprayed (TPS). Differences in the cellular morphology were found when they were grown on the three different surfaces. An uniform monolayer of cells recovered the S surface, while clusters of multilayered irregularly shaped cells were distributed on the rough SB and TPS surfaces. The adhesion of SaOS-2 cells, as measured after 3h of culture, was not affected by surface roughness. ECM components such as Collagen I (CoI), Fibronectin (FN), Vitronectin (VN) and Tenascin (TN) were secreted and organized only on the SB and TPS surfaces while they remained into the cytoplasm on the S surfaces. Osteopontin and BSP-II were largely detected on the SB and TPS surfaces, while only minimal production was observed on the S ones. These data show that titanium surface roughness affects bone differentiation of osteoblast like-cells, SaOS-2, indicating that surface properties may be able to modulate the osteoblast phenotype. These observations also suggest that the bone healing response around dental implants can be affected by surface topography.

  5. Osteogenic potential of biosilica on human osteoblast-like (SaOS-2) cells.

    PubMed

    Wiens, Matthias; Wang, Xiaohong; Schlossmacher, Ute; Lieberwirth, Ingo; Glasser, Gunnar; Ushijima, Hiroshi; Schröder, Heinz C; Müller, Werner E G

    2010-12-01

    Biosilica is a natural polymer, synthesized by the poriferan enzyme silicatein from monomeric silicate substrates. Biosilica stimulates mineralizing activity and gene expression of SaOS-2 cells. To study its effect on the formation of hydroxyapatite (HA), SaOS-2 cells were grown on different silicatein/biosilica-modified substrates (bone slices, Ca-P-coated coverslips, glass coverslips). Growth on these substrates induced the formation of HA nodules, organized in longitudinal arrays or spherical spots. Nodules of sizes above 1 μm were composed of irregularly arranged HA prism-like nanorods, formed by aggregates of three to eight SaOS-2 cells. Moreover, growth on silicatein/biosilica-modified substrates elicited increased [(3)H]dT incorporation into DNA, indicative of enhanced cell proliferation. Consequently, an in vitro-based bioassay was established to determine the ratio between [(3)H]dT incorporation and HA formation. This ratio was significantly higher for cells that grew on silicatein/biosilica-modified substrates than for cells on Ca-P-coated coverslips or plain glass slips. Hence, we propose that this ratio of in vitro-determined parameters reflects the osteogenic effect of different substrates on bone-forming cells. Finally, qRT-PCR analyses demonstrated that growth of SaOS-2 cells on a silicatein/biosilica matrix upregulated BMP2 (bone morphogenetic protein 2, inducer of bone formation) expression. In contrast, TRAP (tartrate-resistant acid phosphatase, modulator of bone resorption) expression remained unaffected. We conclude that biosilica shows pronounced osteogenicity in vitro, qualifying this material for studies of bone replacement also in vivo.

  6. Response of osteoblast-like SAOS-2 cells to zirconia ceramics with different surface topographies.

    PubMed

    Hempel, Ute; Hefti, Thomas; Kalbacova, Marie; Wolf-Brandstetter, Cornelia; Dieter, Peter; Schlottig, Falko

    2010-02-01

    Zirconia is a suitable biomaterial for use in medicine (stomatology, orthopaedics) due to its good biocompatibility and outstanding mechanical properties. This study compares the effect of (i) zirconia to the widely used titanium and (ii) zirconia with two different surface topographies (sandblasted and sandblasted/etched) on the adhesion, proliferation and differentiation of SAOS-2 osteoblasts. SAOS-2 cells were cultured on either sandblasted or sandblasted/etched zirconia and compared with sandblasted/etched titanium. 2 and 24 h after plating, cell morphology was investigated by scanning electron microscope (SEM) and fluorescence imaging. At 24 and 48 h, cell number-relevant parameters were determined. Alkaline phosphatase (ALP) activity and mineral accumulation were measured at days 8, 11, 15 and day 22 of culture, respectively. SEM and fluorescence images revealed a faster spreading as well as higher number of adherent cells after 24 h incubation on zirconia compared with titanium. Also, the cellular metabolic activity after 24 h and the proliferation rate after 48 h is higher with zirconia compared with titanium. Zirconia had a more pronounced effect compared with titanium on the differentiation of SAOS-2 cells: ALP activity, an early differentiation marker increased earlier and mineralization, a late differentiation marker was increased. Only minor differences were found between zirconia with two different surface topographies; etched zirconia promoted slightly greater the differentiation of SAOS-2 cells. These data indicate that zirconia mediates a pronounced stronger effect on the adhesion, proliferation and differentiation compared with titanium; and that topographical differences of zirconia have minor effects on osteoblast biology.

  7. 41. Historic American Buildings Survey San Francisco CallBulletin Library San ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Historic American Buildings Survey San Francisco Call-Bulletin Library San Francisco, California INTERIOR VIEW OF CHURCH BEFORE RESTORATION - 1934 - Mission San Carlos Borromeo, Rio Road & Lausen Drive, Carmel-by-the-Sea, Monterey County, CA

  8. 76 FR 45421 - Drawbridge Operation Regulation; China Basin, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-29

    ... necessary to allow the public to cross the bridge to participate in the scheduled San Francisco Marathon, a..., 2011, to allow participants in the San Francisco Marathon to cross the bridge during the event. This...

  9. 78 FR 31414 - Drawbridge Operation Regulation; China Basin, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-24

    ... cross the bridge to participate in the scheduled San Francisco Marathon, a community event. This... participants in the San Francisco Marathon to cross the bridge during the event. This temporary deviation has...

  10. Hospitalization flow in the public and private systems in the state of Sao Paulo, Brazil

    PubMed Central

    Rocha, Juan Stuardo Yazlle; Monteiro, Rosane Aparecida; Moreira, Marizélia Leão

    2015-01-01

    OBJECTIVE To describe the migration flows of demand for public and private hospital care among the health regions of the state of Sao Paulo, Brazil. METHODS Study based on a database of hospitalizations in the public and private systems of the state of Sao Paulo, Southeastern Brazil, in 2006. We analyzed data from 17 health regions of the state, considering people hospitalized in their own health region and those who migrated outwards (emigration) or came from other regions (immigration). The index of migration effectiveness of patients from both systems was estimated. The coverage (hospitalization coefficient) was analyzed in relation to the number of inpatient beds per population and the indexes of migration effectiveness. RESULTS The index of migration effectiveness applied to the hospital care demand flow allowed characterizing health regions with flow balance, with high emigration of public and private patients, and with high attraction of public and private patients. CONCLUSIONS There are differences in hospital care access and opportunities among health regions in the state of Sao Paulo, Brazil. PMID:26465661

  11. Hospitalization flow in the public and private systems in the state of Sao Paulo, Brazil.

    PubMed

    Rocha, Juan Stuardo Yazlle; Monteiro, Rosane Aparecida; Moreira, Marizélia Leão

    2015-01-01

    OBJECTIVE To describe the migration flows of demand for public and private hospital care among the health regions of the state of Sao Paulo, Brazil.METHODS Study based on a database of hospitalizations in the public and private systems of the state of Sao Paulo, Southeastern Brazil, in 2006. We analyzed data from 17 health regions of the state, considering people hospitalized in their own health region and those who migrated outwards (emigration) or came from other regions (immigration). The index of migration effectiveness of patients from both systems was estimated. The coverage (hospitalization coefficient) was analyzed in relation to the number of inpatient beds per population and the indexes of migration effectiveness.RESULTS The index of migration effectiveness applied to the hospital care demand flow allowed characterizing health regions with flow balance, with high emigration of public and private patients, and with high attraction of public and private patients.CONCLUSIONS There are differences in hospital care access and opportunities among health regions in the state of Sao Paulo, Brazil.

  12. Atlantic tropical forest mapping in the northern coastal zone of Sao Paulo State, Brazil

    SciTech Connect

    Simi, R. Jr.; Almeida, S.A.S.; Manso, A.P.

    1997-06-01

    The northern coastal zone of Sao Paulo State includes the cities of Ubatuba, Caraguatatuba, Sao Sebastiao and Ilha Bela. Large development projects, such as road and highway constructions and joint real estate exploration of susceptible coastal ecosystems have threatened the harmony and ecological stability of these ecosystems. Recently, the Atlantic tropical rain forest has been the most destructed ecosystem in the coastal zone in response to real estate investments in urban areas along the main roads. In the northern coastal zone of Sao Paulo State, 80% of the counties are included in the State Park of Serra do Mar. As tourism is a strong growing economical activity, as well as coastal production, it should be of interest to create a plan for sustainable development. The objective of this study is to map and characterize land use cover changes with emphasis on the Atlantic tropical rain forest degradation using Landsat TM images. Preliminary results for land use cover changes indicate that the Atlantic tropical rain forest was reduced by 6.1 % during the period of July 1992 and October 1995.

  13. Preliminary Goddard geopotential using optical tracking data and a comparison with SAO models

    NASA Technical Reports Server (NTRS)

    Lerch, F. J.; Wagner, C. A.; Putney, B. H.; Nickerson, K. G.

    1971-01-01

    A preliminary Goddard Space Flight Center (GSFC) geopotential and center of mass station coordinate solution was obtained from satellite orbital data using numerical integration theory. This geodetic solution is a prelude to a more general solution which will combine the 1971 International Satellite Geodesy Experiment (ISAGEX) laser data with the present data being employed. The present GSFC geopotential solution consists of the spherical harmonic coefficients through degree and order eight with higher order satellite resonant coefficients. The solution represents a first iteration result from 17 satellites with approximately 150 weekly orbital arcs containing some 40,000 optical observations. The GSFC preliminary result is compared with final results from the Smithsonian Astrophysical Observatory (SAO) solutions including the 1969 SAO Standard Earth II solution. One aspect of interest for the comparison is that SAO uses an analytic theory for the orbital solution whereas GSFC uses a numerical integration theory. The comparison of geopotential results shows that good agreement exists in general but that there are some areas of minor differences.

  14. VizieR Online Data Catalog: SAO-HD-GC-DM Cross Index (ADC 1983) (Roman+ 1983)

    NASA Astrophysics Data System (ADS)

    Roman, N. G.; Warren, W. H., Jr.; Schofield, N. J., Jr.

    1996-05-01

    The catalog is an updated, corrected, and extended version of a table of correspondences originally prepared by Morin (1973). The individual data corrections, additions, and changes included in the new version number 11398, with 8600 data records having at least one change. In addition to the correction of all errors found since preparation of the original catalog, most of which resulted from misidentifications and omissions of components in multiple-star systems and missing Durchmusterung numbers (the common identifier) in the SAO Catalog, component identifications from the Index Catalogue of Visual Double Stars (IDS) have been appended to all multiple SAO stars having the same DM numbers, and lowercase identifications for supplemental (footnoted) BD stars have been added. Stars deleted (duplicate entries) in the SAO Catalog have been appended with a "D" and their data removed, although the records have been kept (with SAO number only) in order not to change the number of SAO stars. The data include SAO number, HD number, HD multiplicity code, GC number, DM identification code (BD, CD, CP), and number. There are fewer objects than records because of the deleted entries appended with a "D" as described above (35 stars deleted). (1 data file).

  15. Small-scale upper mantle flow during the initiation of craton destruction

    NASA Astrophysics Data System (ADS)

    Zhao, Liang; Wang, Kun; Xu, Xiaobing

    2017-04-01

    The North China Craton (NCC) is an old craton which has experienced multi-episodic tectonism with surrounding plates. Bordered to the north by Xing'an-Mongolian Orogenic Belt, to the south by Qingling-Dabie-Sulu Orogen and to the far-east by (Paleo-) Pacific plate, the NCC has lost the cratonic properties within its eastern part. Evidently, the initiation and mechanism of craton destruction attract tremendous attention and remain hot debated. During the Mesozoic to the Cenozoic, the northeastern part of the NCC has been intensively revoked, along with the transition from NE shortening to NW-SE extension. The subduction of Paleo-Pacific plate becomes the prime suspect due to the same kinematic direction. Here we present a hybrid shear wave splitting measurement to investigate the mantle deformation of the NCC, and intend to constrain geodynamic process during the initiation of craton destruction. The SKS waveform data is recorded from 60 broadband stations with an average spacing of 15 km. We employ the traditional routine method to obtain fast polarization directions (FPDs, Φ) and delay times (δt) for the teleseismic events with epicenter range in 85°-115°. One may often have troubles in delimiting SKS and S wave with regard to the events at distances <85°. Waveform modeling has the advantages through repeated compatibility tests which thus can help us acquire more accurate Φ and δt. Combining these two methods, we depict the major FPDs overlapping on the geological map. Three segments along the profile exhibit NW-SE trending, which are parallel to the extension direction recorded in Erlian Basin, Songliao Basin and metamorphic core complex in Liaoning Peninsula. However, the in-between E-W trending FPDs cannot be neglected. Our previous tomography results show a high-velocity anomaly extend to the depth greater than 200 km beneath the Yanshan belt (118°-120°E). In comparison with other SKS observations in the NCC, the east-end nearly E-W FPD is possibly

  16. San Francisco Bay, California as seen from STS-59

    NASA Technical Reports Server (NTRS)

    1994-01-01

    San Francisco Bay as seen from STS-59. View is oriented with the sea up. The delta of the combined Sacramento and San Joaquin Rivers occupies the foreground with San Francisco Bay in the middle distance, then the Pacific Ocean. Variations in water color caused both by sediment load and by wind streaking strike the eye. Man-made features dominate this scene. The Lafayette/Concord complex is left of the bay head, Vallejo is to the right, the Berkeley/Oakland complex rims the shoreline of the main bay, and San Francisco fills the peninsula beyond. Salt-evaporation ponds contain differently-colored algae depending on salinity. The low altitude (less than 120 nautical miles) and unusually-clear air combine to provide unusually-strong green colors in this Spring scene.

  17. Survey of SLAC lands for San Francisco garter snake

    SciTech Connect

    Seib, R.L.; Papenfuss, T.J.

    1981-11-01

    The San Francisco garter snake (Thamnophis sirtalis tetrataenia) is protected under the endangered species act by the US Fish and Wildlife Service and the California Department of Fish and Game. The snake is restricted to the San Francisco peninsula and all known populations are in San Mateo County. In southeastern San Mateo County and northwestern Santa Clara County T. s. tetrataenia intergrades with T. s. infernalis. The Stanford Linear Accelerator Center (SLAC) lands are located in this area of intergradation. SLAC contracted Robert Seib and Ted Papenfuss to survey SLAC lands during September and early November 1981, to determine the possibility of occurrence of the San Francisco garter snake on their lands. Results of this investigation and management recommendations are presented here.

  18. What is causing the phytoplankton increase in San Francisco Bay?

    USGS Publications Warehouse

    Cloern, J.E.; Jassby, A.D.; Schraga, T.S.; Dallas, K.L.

    2006-01-01

    The largest living component of San Francisco Bay is the phytoplankton, a suspension of microscopic cells that convert sunlight energy into new living biomass through the same process of photosynthesis used by land plants. This primary production is the ultimate source of food for clams, zooplankton, crabs, sardines, halibut, sturgeon, diving ducks, pelicans, and harbor seals. From measurements made in 1980, we estimated that phytoplankton primary production in San Francisco Bay was about 200,000 tons of organic carbon per year (Jassby et al. 1993). This is equivalent to producing the biomass of 5500 adult humpback whales, or the calories to feed 1.8 million people. These numbers may seem large, but primary production in San Francisco Bay is low compared to many other nutrient-enriched estuaries.

  19. San Francisco Bay, California as seen from STS-59

    NASA Technical Reports Server (NTRS)

    1994-01-01

    San Francisco Bay as seen from STS-59. View is oriented with the sea up. The delta of the combined Sacramento and San Joaquin Rivers occupies the foreground with San Francisco Bay in the middle distance, then the Pacific Ocean. Variations in water color caused both by sediment load and by wind streaking strike the eye. Man-made features dominate this scene. The Lafayette/Concord complex is left of the bay head, Vallejo is to the right, the Berkeley/Oakland complex rims the shoreline of the main bay, and San Francisco fills the peninsula beyond. Salt-evaporation ponds contain differently-colored algae depending on salinity. The low altitude (less than 120 nautical miles) and unusually-clear air combine to provide unusually-strong green colors in this Spring scene.

  20. San Francisco Bay, California as seen from STS-59

    NASA Image and Video Library

    1994-04-14

    STS059-213-009 (9-20 April 1994) --- San Francisco Bay. Orient with the sea up. The delta of the combined Sacramento and San Joaquin Rivers occupies the foreground, San Francisco Bay the middle distance, and the Pacific Ocean the rest. Variations in water color caused both by sediment load and by wind streaking strike the eye. Man-made features dominate this scene. The Lafayette/Concord complex is left of the bay head, Vallejo is to the right, the Berkeley/Oakland complex rims the shoreline of the main bay, and San Francisco fills the peninsula beyond. Salt-evaporation ponds contain differently-colored algae depending on salinity. The low altitude (less than 120 nautical miles) and unusually-clear air combine to provide unusually-strong green colors in this Spring scene. Hasselblad camera.

  1. Developing Alternative Placement Criteria for English Courses at City College of San Francisco. Issue Brief

    ERIC Educational Resources Information Center

    Castrechini, Sebastian

    2013-01-01

    Recognizing the need to improve postsecondary access and success for underrepresented populations, the San Francisco Unified School District (SFUSD), City College of San Francisco (CCSF), the City and County of San Francisco, and key community organizations formed the Bridge to Success initiative in 2009. The John W. Gardner Center for Youth and…

  2. 75 FR 65985 - Safety Zone: Epic Roasthouse Private Party Firework Display, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-27

    ... off Epic Roasthouse Restaurant, San Francisco, CA during a fireworks display in support of the Epic... Restaurant, San Francisco, CA. The fireworks display is meant for entertainment purposes. This safety zone is... Epic Roasthouse Restaurant, San Francisco, CA. The fireworks launch site will be located in position 37...

  3. 33 CFR 165.1192 - Security Zones; Waters surrounding San Francisco International Airport and Oakland International...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zones; Waters surrounding San Francisco International Airport and Oakland International Airport, San Francisco Bay... Security Zones; Waters surrounding San Francisco International Airport and Oakland International...

  4. 33 CFR 165.1192 - Security Zones; Waters surrounding San Francisco International Airport and Oakland International...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zones; Waters surrounding San Francisco International Airport and Oakland International Airport, San Francisco Bay... Security Zones; Waters surrounding San Francisco International Airport and Oakland International...

  5. 77 FR 73311 - Special Local Regulation and Safety Zone; America's Cup Sailing Events, San Francisco, CA...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-10

    ... waters of San Francisco Bay adjacent to the City of San Francisco waterfront in the vicinity of the... access to pier space and facilities along the City of San Francisco waterfront and to minimize other...-September 23, 2013). An image illustrating the location of the transit zone is available in the docket....

  6. Variations of the lithospheric strength across the edges of the North American craton and their relation to intraplate earthquakes

    NASA Astrophysics Data System (ADS)

    Tesauro, Magdala; Kaban, Mikhail; Mooney, Walter; Cloetingh, Sierd

    2016-04-01

    Seismic tomography models revealed a pronounced velocity contrast between the cratonic and off-cratonic regions of North America. However, the location of the transition between the fast/slow velocities characterizing the Archean-Proterozoic and Phanerozoic regions, respectively, is still under debate. In order to understand the structure of the edges of North American (NA) cratons, we analyze the results of two recent thermal and strength models of the NA continent, obtained using seismic and gravity data (Kaban et al., 2014; Tesauro et al., 2014; 2015). We could observe that in the peripheral parts of the cratons, as the Proterozoic Canadian Platform, the Grenville, and the western part of the Yavapai-Mazatzal province, the integrated strength for one model is 10 times larger than the other one, due to a temperature difference of >200°C in the uppermost mantle. The differences in the effective elastic thickness (Te) between the two models are less pronounced. In both models, Proterozoic regions reactivated by Meso-Cenozoic tectonics (e.g., Rocky Mountains and the Mississippi Embayment), are characterized by a weak lithosphere due to the absence of the mechanically strong part of the mantle lithospheric layer. Furthermore, intraplate earthquakes are distributed along the edges of the cratons, demonstrating that tectonic stress accumulates there, while the cores of the cratons remain undeformed. In both models, intraplate seismicity occurs in weak lithosphere or in the regions characterized by pronounced contrasts of strength and Te.

  7. Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction

    NASA Astrophysics Data System (ADS)

    Pilet, Sebastien; Guex, Jean; Muntener, Othmar; Bartolini, Annachiara; Spangenberg, Jorge; Schoene, Blair; Schaltegger, Urs

    2016-04-01

    The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here, we present a synthesis of stratigraphic constraints on the Triassic-Jurassic (T-J) and Pliensbachian-Toarcian (Pl-To) boundaries combined with geochronological data in order to establish the sequence of events that initiate two of the major mass extinctions recorded in Earth's history. This synthesis demonstrates that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. The initial regressive events recorded at T-J and Pl-To boundaries seem difficult to reconcile either with large initial CO2 degassing associated with plume activity or by volatile-release (CO2, CH4, Cl2) from deep sedimentary reservoirs during contact metamorphism associated to dykes and sills intrusion because massive CO2 degassing is expected to produce super greenhouse conditions. We evaluate, here, an alternative suggesting that the initial cooling could be due to gas release during the initial thermal erosion of the cratonic lithosphere due to emplacement of the CAMP and Karoo-Ferrar volcanic provinces. Petrological constraints on primary magmas indicate that the mantle is hotter and melts more extensively to produce LIP lavas than for current oceanic islands basalts. However, available data suggest that the Karoo and CAMP areas were underlain by thick lithosphere (>200 km) prior to continental break up. The presence of thick lithosphere excludes significant melting of the asthenospheric mantle without initial stage of thermal erosion of the cratonic lithosphere. This initial step of thermal erosion / thermal heating of the cratonic lithosphere is critical to understand the volatile budget associated with LIPs while

  8. Mantle density beneath the Siberian craton based on free board constrains

    NASA Astrophysics Data System (ADS)

    Cherepanova, Yulia; Artemieva, Irina

    2014-05-01

    We present the mantle density model of the Archean-Proterozoic Siberian Craton (SC). The density model is constrained by free-board (buoyancy) modeling (Lachenbruch and Morgan, 1990). The approach assumes isostatic compensation of the region, and is justified by the near-zero free-air gravity for most of the region, except for the flanking orogenic belts with high topography. Despite a relatively uniform topography of the SC (ca. 400 m for most of the region and reaching 700 m in the shields), the craton has a strongly heterogeneous crustal structure with large regional variations in Moho and average crustal Vp (Cherepanova et al., 2013) which reflects its complex tectonic evolution. Formed by amalgamation of several Archean terranes, the craton has been significantly affected by Proterozoic collisional and extensional events, the late- Proterozoic rifting at its margins, the Devonian rifting of the Vilyui rift, several pulses of kimberlite magmatism, and the Permo-Triassic trap basalt magmatism. The strong lateral and vertical heterogeneity of the lithospheric mantle has been documented so far in the studied of the mantle xenoliths from kimberlite pipes and in a limited number of geophysical studies. Here we extend geophysical analysis of mantle compositional heterogeneity by evaluating mantle density structure and interpreting its regional variations in terms of mantle mg#. We link regional large-amplitude variations in mantle depletion to the tectonic evolution of the craton and compare these results with geophysical models and petrologic data. We speculate on the origin of compositional heterogeneity of the lithospheric mantle, which is in overall agreement with results of a joint analysis of seismic and thermal data (Artemieva, 2009) and mantle xenolith studies which provide information on metasomatic enrichment of the depleted lithospheric mantle by the tectonic events. The results indicate the heterogeneous structure of mantle density, with the average

  9. Very Broad Band Seismic Constraints on the LAB and Lithospheric Layering in the north American Craton

    NASA Astrophysics Data System (ADS)

    Romanowicz, Barbara; Yuan, Huaiyu; Clouzet, Pierre; Caló, Marco; Roy, Corinna; Bodin, Thomas; Maurya, Satish

    2017-04-01

    Several types of geophysical observations have been used to estimate the thickness of the lithosphere in continental cratons worldwide. Heat flow measurements, geochemical analyses, magnetotelluric data and seismic tomography all concur that, in its oldest parts, the cratonic lithosphere is on average 200-250 km thick. An outstanding question is how such a thick lithosphere was formed and how it could have been maintained since Archean times. Another puzzling observation is that in many areas, receiver function (RF) studies fail to detect conversions from the lithosphere-asthenosphere boundary (LAB), and, instead, detect a sharp velocity drop at much shallower depths, that defines a mid-lithospheric discontinuity (MLD). In the north American continent, the LAB, and an MLD (that may or may not coincide with that found in RF studies) are well defined through changes in the direction of the fast axis of azimuthal anisotropy as found from combined inversion of long period seismic waveforms and SKS splitting data (e.g. Yuan and Romanowicz, 2010). We here review how these results relate to more recent analyses that take advantage of the dense sampling of north America owing to the deployment of the USArray and other temporary or permanent broadband networks, combined with Bayesian trans-dimensional modeling of crust and upper-mantle radial and azimuthal anisotropic structure obtained locally at a representative set of stations in north America (e.g. Caló et al., 2016). We describe evidence for the detection of the LAB and, in some cases, of several mid-lithospheric discontinuities, using a combination of constraints from long period seismic data and converted phases, which suggest formation of the cratonic lithosphere through successive under-plating by layers of different composition. We discuss the possible origin of the high shear velocities observed in North America and other cratons in the depth range 120-150 km.

  10. Olivine water contents in the continental lithosphere and the longevity of cratons.

    PubMed

    Peslier, Anne H; Woodland, Alan B; Bell, David R; Lazarov, Marina

    2010-09-02

    Cratons, the ancient cores of continents, contain the oldest crust and mantle on the Earth (>2 Gyr old). They extend laterally for hundreds of kilometres, and are underlain to depths of 180-250 km by mantle roots that are chemically and physically distinct from the surrounding mantle. Forming the thickest lithosphere on our planet, they act as rigid keels isolated from the flowing asthenosphere; however, it has remained an open question how these large portions of the mantle can stay isolated for so long from mantle convection. Key physical properties thought to contribute to this longevity include chemical buoyancy due to high degrees of melt-depletion and the stiffness imparted by the low temperatures of a conductive thermal gradient. Geodynamic calculations, however, suggest that these characteristics are not sufficient to prevent the lithospheric mantle from being entrained during mantle convection over billions of years. Differences in water content are a potential source of additional viscosity contrast between cratonic roots and ambient mantle owing to the well-established hydrolytic weakening effect in olivine, the most abundant mineral of the upper mantle. However, the water contents of cratonic mantle roots have to date been poorly constrained. Here we show that olivine in peridotite xenoliths from the lithosphere-asthenosphere boundary region of the Kaapvaal craton mantle root are water-poor and provide sufficient viscosity contrast with underlying asthenosphere to satisfy the stability criteria required by geodynamic calculations. Our results provide a solution to a puzzling mystery of plate tectonics, namely why the oldest continents, in contrast to short-lived oceanic plates, have resisted recycling into the interior of our tectonically dynamic planet.

  11. Early proterozoic evolution of the saskatchewan craton and its allochthonous coyer, trans-hudson Orogen

    USGS Publications Warehouse

    Chiarenzelli, J.; Aspler, L.; Villeneuve, M.; Lewry, J.

    1998-01-01

    The composition, chronology, and structural relations of the Saskatchewan Craton and enveloping mylonitic rocks exposed in basement windows of the Glennie Domain, Trans-Hudson Orogen, have been determined by geochemical, geochronologic, and structural studies accompanying detailed field mapping. Basement windows lie along the hinge zone of a regional crustal culmination and consist mostly of 2.4-2.5 Ga felsic plutonic rocks enveloped by the Nistowiak Thrust. The Nistowiak Thrust is a folded, 1-2 km thick, upper amphibolite facie??s mylonite zone formed during emplacement of the Flin Flon-Glennie Complex across the Saskatchewan Craton. It is likely correlative to the Pelican Thrust, which envelops basement windows in the Hanson Lake Block -100 km to the east. An internal high strain zone within the overlying nappe pile, the Guncoat Thrust, is composed primarily of mylonitized porphyroclastic pelitic and psammitic migmatites. U-Pb geochronological results suggest calc-alkaline plutonism from 1889-1837 Ma, thrust stacking, peak metamorphism and associated anatexis between 1837 and 1809 Ma, isotopic closure of titanite at 1790-1772 Ma, and intrusion of late granitic rocks at 1770-1762 Ma. This is in agreement with ages from the Hanson Lake Block, and La Ronge, Kisseynew, and Flin-Flon domains in Saskatchewan and Manitoba, and from the Ungava-Baffin portion of Trans-Hudson Orogen, suggesting broadly synchronous thermotectonic processes along a strike length of 2000 km. We speculate that the Saskatchewan Craton, rather than representing an exotic continental fragment, rifted from the Superior and/or Hearne Provinces at ca. 2.1 Ga and that the Trans-Hudson Orogen is an internal orogen. In this scenario the Maniwekan Ocean, developed between the Rae-Hearne and Superior cratons, opened and closed about similar pole(s) of plate motion. ?? 1998 by The University of Chicago. All rights reserved.

  12. Lower Crustal Seismicity, Volatiles, and Evolving Strain Fields During the Initial Stages of Cratonic Rifting

    NASA Astrophysics Data System (ADS)

    Lambert, C.; Muirhead, J.; Ebinger, C. J.; Tiberi, C.; Roecker, S. W.; Ferdinand-Wambura, R.; Kianji, G.; Mulibo, G. D.

    2014-12-01

    The volcanically active East African rift system in southern Kenya and northern Tanzania transects thick cratonic lithosphere, and comprises several basins characterized by deep crustal seismicity. The US-French-Tanzania-Kenya CRAFTI project aims to understand the role of magma and volatile movement during the initiation and evolution of rifting in cratonic lithosphere. Our 38-station broadband network spans all or parts of fault-bounded rift segments, enabling comparison of lithospheric structure, fault kinematics, and seismogenic layer thickness with age and proximity to the deeply rooted Archaen craton. Seismicity levels are high in all basins, but we find profound differences in seismogenic layer thickness along the length of the rift. Seismicity in the Manyara basin occurs almost exclusively within the lower crust, and in spatial clusters that have been active since 1990. In contrast, seismicity in the ~ 5 My older Magadi basin is localized in the upper crust, and the long border fault bounding the west side of the basin is seismically inactive. Between these two basins lies the Natron rift segment, which shows seismicity between ~ 20 and ~2 km depth, and high concentrations at Oldoinyo Lengai and Gelai volcanoes. Older volcanoes on the uplifted western flank (e.g., Ngorongoro) experience swarms of activity, suggesting that active magmatism and degassing are widespread. Focal mechanisms of the frequent earthquakes recorded across the array are spatially variable, and indicate a stress field strongly influenced by (1) Holocene volcanoes, (2) mechanical interactions between adjacent rift basins, and (3) a far-field ESE-WNW extensional stress regime. We explore the spatial correlation between zones of intense degassing along fault systems and seismicity, and examine the influence of high gas pressures on lower and upper crustal seismicity in this youthful cratonic rift zone.

  13. Crustal and Lithospheric Structure across the Boundary of the East European Craton from Receiver Functions

    NASA Astrophysics Data System (ADS)

    Knapmeyer-Endrun, B.; Krueger, F.

    2014-12-01

    The Trans-European Suture Zone (TESZ), which extends from the North Sea to the Black Sea, marks a fundamental lithospheric boundary in Europe. It separates the East European Craton to the north-east, which has been stable for at least 1.45 Ga, from the younger lithosphere of Phanerozoic Europe to the south-west. In this study we use a large dataset of more than 40,000 teleseismic P- and S-receiver functions from almost 500 seismological stations to image crustal and lithospheric structure across central and eastern Europe between the Benelux and the Baltic countries. An important data source is the PASSEQ project, which deployed close to 200 temporary stations between Germany and Lithuania for two years with the aim to obtain detailed, 3D information on the upper mantle structure across the TESZ. Combining P and S observations, we find a stepwise transition in crustal thickness, spread over 200 km laterally, from on average of 30 km in Phanerozoic Europe to more than 45 km beneath the East European Craton. Individual Paleoproterozoic terranes in Lithuania can also be distinguished based on crustal thickness. Crustal layering is not resolved with the receiver functions, but a high Poisson's ratio of 0.27 is obtained for the craton, compared to 0.25 for Phanerozoic Europe, which is consistent with a thick mafic lower crust. Moho depth results show an excellent correlation with the interpretation of a seismic line in the area, lending confidence to the interpretation of deeper structures. The lithosphere-asthenosphere boundary (LAB), as mapped by S-receiver functions, is located at an average depth of 90 km beneath Phanerozoic Europe. Towards the east, the LAB is dipping to about 125 km depth beneath the Elbe Line. Below the craton, a mid-lithospheric discontinuity is found at about 80 km depth, whereas weak indications of the LAB are found at an average depth of 260 km.

  14. Seismic structure of a late-Archean microcontinent in the middle of the Western Australian Craton

    NASA Astrophysics Data System (ADS)

    Yuan, Huaiyu; Johnson, Simon; Dentith, Mike; Murdie, Ruth; Gessner, Klaus; Korhonen, Fawna; Bodin, Thomas

    2017-04-01

    The Capricorn Orogen recorded the Paleoproterozoic amalgamation of the Archean Pilbara and Yilgarn cratons to form the Western Australian Craton. Regional surveys involving geological mapping, geochemistry, and geophysics reveal a prolonged tectonic history in craton assembly and subsequent intracratonic reworking, which have significantly re-shaped the orogenic crust. A high-density earthquake seismology deployment targeted the Glenburgh Terrane, an exotic late-Archean to Paleoproterozoic crustal block previously inferred from distinct structural and isotopic characters in the core region of the terrane. Prominent Moho and intracrustal discontinuities are present, replicating the overall trend and depth range found in the previous high-resolution deep crustal reflection image. Significant lateral variations in the seismic signal are found across the terrane boundary, showing a relatively thin crust (<40km) with small Vp/Vs ratios ( 1.70) in the Glenburgh terrane, compared with the thickened (>40km) crust with elevated Vp/Vs ratios (>1.76) in the margin. The small Vp/Vs ratios ( 1.70) are mapped terrane-wide, indicating a felsic bulk crustal composition. Considering the available constraints from isotopic age, magnetotelluric models and absolute shear wave velocities from ambient noise tomography, the Glenburgh Terrane is interpreted as a microcontinent made in the Archean, which however may have been altered during the WAC assembly and cratonization, as well as subsequent intracratonic reworking/magmatic differentiation processes. Our results illustrate that multi-disciplinary datasets bring complementary resolution and therefore may put tighter constraints on the tectonic processes that have affected the crust.

  15. Magnetotelluric investigations of the lithosphere beneath the central Rae craton, mainland Nunavut, Canada

    NASA Astrophysics Data System (ADS)

    Spratt, Jessica E.; Skulski, Thomas; Craven, James A.; Jones, Alan G.; Snyder, David B.; Kiyan, Duygu

    2014-03-01

    New magnetotelluric soundings at 64 locations throughout the central Rae craton on mainland Nunavut constrain 2-D resistivity models of the crust and lithospheric mantle beneath three regional transects. Responses determined from colocated broadband and long-period magnetotelluric recording instruments enabled resistivity imaging to depths of > 300 km. Strike analysis and distortion decomposition on all data reveal a regional trend of 45-53°, but locally the geoelectric strike angle varies laterally and with depth. The 2-D models reveal a resistive upper crust to depths of 15-35 km that is underlain by a conductive layer that appears to be discontinuous at or near major mapped geological boundaries. Surface projections of the conductive layer coincide with areas of high grade, Archean metasedimentary rocks. Tectonic burial of these rocks and thickening of the crust occurred during the Paleoproterozoic Arrowsmith (2.3 Ga) and Trans-Hudson orogenies (1.85 Ga). Overall, the uppermost mantle of the Rae craton shows resistivity values that range from ~3000 Ω m in the northeast (beneath Baffin Island and the Melville Peninsula) to ~10,000 Ω m beneath the central Rae craton, to >50,000 Ω m in the south near the Hearne Domain. Near-vertical zones of reduced resistivity are identified within the uppermost mantle lithosphere that may be related to areas affected by mantle melt or metasomatism associated with emplacement of Hudsonian granites. A regional decrease in resistivities to values of ~500 Ω m at depths of 180-220 km, increasing to 300 km near the southern margin of the Rae craton, is interpreted as the lithosphere-asthenosphere boundary.

  16. Cold cratonic roots and thermal blankets: How continents affect mantle convection

    USGS Publications Warehouse

    Trubitsyn, V.P.; Mooney, W.D.; Abbott, D.H.

    2003-01-01

    Two-dimensional convection models with moving continents show that continents profoundly affect the pattern of mantle convection. If the continents are wider than the wavelength of the convection cells (???3000 km, the thickness of the mantle), they cause neighboring deep mantle thermal upwellings to coalesce into a single focused upwelling. This focused upwelling zone will have a potential temperature anomaly of about 200??C, much higher than the 100??C temperature anomaly of upwelling zones generated beneath typical oceanic lithosphere. Extensive high-temperature melts (including flood basalts and late potassic granites) will be produced, and the excess temperature anomaly will induce continental uplift (as revealed in sea level changes) and the eventual breakup of the supercontinent. The mantle thermal anomaly will persist for several hundred million years after such a breakup. In contrast, small continental blocks (<1000 km diameter) do not induce focused mantle upwelling zones. Instead, small continental blocks are dragged to mantle downwelling zones, where they spend most of their time, and will migrate laterally with the downwelling. As a result of sitting over relatively cold mantle (downwellings), small continental blocks are favored to keep their cratonic roots. This may explain the long-term survival of small cratonic blocks (e.g., the Yilgarn and Pilbara cratons of western Australia, and the West African craton). The optimum size for long-term stability of a continental block is <3000 km. These results show that continents profoundly affect the pattern of mantle convection. These effects are illustrated in terms of the timing and history of supercontinent breakup, the production of high-temperature melts, and sea level changes. Such two-dimensional calculations can be further refined and tested by three-dimensional numerical simulations of mantle convection with moving continental and oceanic plates.

  17. Intraplate deformation on north-dipping basement structures in the Northern Gawler Craton, Australia: reactivation of original terrane boundaries or later intra-cratonic thrusts?

    NASA Astrophysics Data System (ADS)

    Baines, G.; Giles, D.; Betts, P. G.; Backé, G.

    2007-12-01

    Multiple intraplate orogenic events have deformed Neoproterozoic to Carboniferous sedimentary sequences that cover the Archean to Mesoproterozoic basement of the northern Gawler Craton, Australia. These intraplate orogenies reactivated north-dipping basement penetrating faults that are imaged on seismic reflection profiles. These north-dipping structures pre-date Neoproterozoic deposition but their relationships to significant linear magnetic and gravity anomalies that delineate unexposed Archean to Early Mesoproterozoic basement terranes are unclear. The north-dipping structures are either terrane boundaries that formed during continental amalgamation or later faults, which formed during a mid- to late-Mesoproterozoic transpressional orogeny and cross-cut the original lithological terrane boundaries. We model magnetic and gravity data to determine the 3D structure of the unexposed basement of the northern Gawler Craton. These models are constrained by drill hole and surface observations, seismic reflection profiles and petrophysical data, such that geologically reasonable models that can satisfy the data are limited. The basement structures revealed by this modelling approach constrain the origin and significance of the north-dipping structures that were active during the later intraplate Petermann, Delamerian and Alice Springs Orogenies. These results have bearing on which structures are likely to be active during present-day intraplate deformation in other areas, including, for example, current seismic activity along similar basement structures in the Adelaide "Geosyncline".

  18. Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction.

    PubMed

    Guex, Jean; Pilet, Sebastien; Müntener, Othmar; Bartolini, Annachiara; Spangenberg, Jorge; Schoene, Blair; Sell, Bryan; Schaltegger, Urs

    2016-03-24

    The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here we present a synthesis of ammonite biostratigraphy, isotopic data and high precision U-Pb zircon dates from the Triassic-Jurassic (T-J) and Pliensbachian-Toarcian (Pl-To) boundaries demonstrating that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. We explain these transitions as a result of changing gas species emitted during the progressive thermal erosion of cratonic lithosphere by plume activity or internal heating of the lithosphere. Our petrological model for LIP magmatism argues that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere before CO2 became the dominant gas. This model offers an explanation of why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere.

  19. Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction

    PubMed Central

    Guex, Jean; Pilet, Sebastien; Müntener, Othmar; Bartolini, Annachiara; Spangenberg, Jorge; Schoene, Blair; Sell, Bryan; Schaltegger, Urs

    2016-01-01

    The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here we present a synthesis of ammonite biostratigraphy, isotopic data and high precision U-Pb zircon dates from the Triassic-Jurassic (T-J) and Pliensbachian-Toarcian (Pl-To) boundaries demonstrating that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. We explain these transitions as a result of changing gas species emitted during the progressive thermal erosion of cratonic lithosphere by plume activity or internal heating of the lithosphere. Our petrological model for LIP magmatism argues that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere before CO2 became the dominant gas. This model offers an explanation of why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere. PMID:27009463

  20. How Did the North China Craton Move from Nuna to Rodinia

    NASA Astrophysics Data System (ADS)

    Zhang, S.

    2015-12-01

    Several models that include the paleogeographic positions of the North China Craton (NCC) in Precambrian supercontinents Nuna and Rodinia were tested in this study using Proterozoic global paleomagnetic database. During ca. 1.8 - 1.4 Ga, the NCC can be placed far from Laurentia and Baltica. In Nuna, the present southern margin of the NCC faced an open ocean, whilst its present northern margin was likely connected to Indian and Australian cratons. In Rodinia, however, during ca. 1.1 - 0.85 Ga, the paleomagnetic data indicate a proximate connection between the NCC and the arctic side of Laurentia. These two models, if both are right, suggest that the NCC may have moved a long distance since the departure from Nuna to the joining of Rodinia. Moreover, paleomagnetic data and our reconstructions require many cratons to drift away from their connections in Nuna after ca. 1.35 Ga. These reconstructions strongly challenges the currently influential speculation of limited breakup of Nuna, which is mainly based on the observation of low abundance of passive margins that were formed during the boring billion years (ca. 1.75 - 0.75 Ga).

  1. An isotopic perspective on growth and differentiation of Proterozoic orogenic crust: From subduction magmatism to cratonization

    SciTech Connect

    Johnson, Simon P.; Korhonen, Fawna J.; Kirkland, Christopher L.; Cliff, John B.; Belousova, Elena A.; Sheppard, Stephen

    2017-01-01

    The in situ chemical differentiation of continental crust ultimately leads to the long-term stability of the continents. This process, more commonly known as ‘cratonization’, is driven by deep crustal melting with the transfer of those melts to shallower regions resulting in a strongly chemically stratified crust, with a refractory, dehydrated lower portion overlain by a complementary enriched upper portion. Since the lower to mid portions of continental crust are rarely exposed, investigation of the cratonization process must be through indirect methods. In this study we use in situ Hf and O isotope compositions of both magmatic and inherited zircons from several felsic magmatic suites in the Capricorn Orogen of Western Australia to highlight the differentiation history (i.e. cratonization) of this portion of late Archean to Proterozoic orogenic crust. The Capricorn Orogen shows a distinct tectonomagmatic history that evolves from an active continental margin through to intracratonic reworking, ultimately leading to thermally stable crust that responds similarly to the bounding Archean Pilbara and Yilgarn Cratons.

  2. Reactivation and mantle dynamics of North China Craton: insight from P-wave anisotropy tomography

    NASA Astrophysics Data System (ADS)

    Tian, You; Zhao, Dapeng

    2013-12-01

    We determined the first 3-D P-wave anisotropic tomography beneath the North China Craton (NCC) using a large number of high-quality arrival-time data from local earthquakes and teleseismic events, which reveals depth-dependent azimuthal anisotropy in the crust and upper mantle down to 600 km depth. In the NCC western block, the fast velocity direction (FVD) varies from east-west in the southern part to northeast-southwest in the northern part, which may reflect either the interaction between the Yangtze block and NCC or fossil lithospheric fabrics in the craton. Under the NCC eastern block, a uniform northwest-southeast FVD is revealed in the lower part of the upper mantle (300-410 km depths) and the mantle transition zone (410-660 km depths), which may reflect horizontal and upwelling flows in the big mantle wedge (BMW) above the stagnant Pacific slab in the mantle transition zone. The NCC central block exhibits a northeast-southwest FVD, consistent with the surface tectonic orientation there, suggesting that the cold and thick (>300 km) cratonic root of the NCC western block may obstruct the northwest-southeast trending mantle flow induced by the Pacific Plate subduction, resulting in a northeast-southwest trending mantle flow under the central block. Our present results indicate that the corner flow in the BMW associated with the deep subduction of the Pacific Plate is the main cause of NCC reactivation and mantle dynamics under East China.

  3. Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction

    NASA Astrophysics Data System (ADS)

    Guex, Jean; Pilet, Sebastien; Müntener, Othmar; Bartolini, Annachiara; Spangenberg, Jorge; Schoene, Blair; Sell, Bryan; Schaltegger, Urs

    2016-03-01

    The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here we present a synthesis of ammonite biostratigraphy, isotopic data and high precision U-Pb zircon dates from the Triassic-Jurassic (T-J) and Pliensbachian-Toarcian (Pl-To) boundaries demonstrating that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. We explain these transitions as a result of changing gas species emitted during the progressive thermal erosion of cratonic lithosphere by plume activity or internal heating of the lithosphere. Our petrological model for LIP magmatism argues that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere before CO2 became the dominant gas. This model offers an explanation of why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere.

  4. Lithospheric Structure of the Northeastern North China Craton Imaged by S Receiver Functions

    NASA Astrophysics Data System (ADS)

    Wang, Xingchen; Ding, Zhifeng; Zhu, Lupei

    2016-08-01

    Lithosphere thickness variation is important for understanding the significant tectonic reactivation of the North China Craton (NCC) in the Mesozoic and Cenozoic time. Here, we determined the lithospheric structure in the northeastern NCC using S receiver functions from 305 teleseismic events recorded by 223 seismic stations. The Moho and lithosphere-asthenosphere boundary (LAB) are imaged clearly beneath the region. The Moho depth decreases from ~45 km beneath the western NCC to ~25 km beneath the eastern NCC. We found that the lithospheric thickness varies from 60 to 80 km beneath the Trans-North China Orogen (TNCO) and eastern NCC with no significant change of the LAB depth. The lithosphere thickness beneath the northwestern Ordos plateau is 100-130 km. In addition, there is a mid-lithosphere discontinuity at a depth of 80 km beneath the plateau that is connected to the base of thinned lithosphere in TNCO and eastern NCC. We suggest that the mid-lithosphere discontinuity represents a mechanically weak zone in the original cratonic lithosphere of the NCC. The material in the lower lithosphere of the craton, when warmed and hydrated by water released from the subducting slab of Western Pacific, became weak due to decrease in viscosity and/or partial melting and was subsequently removed through small-scale mantle convections.

  5. Plateau uplift in western Canada caused by lithospheric delamination along a craton edge

    NASA Astrophysics Data System (ADS)

    Bao, Xuewei; Eaton, David W.; Guest, Bernard

    2014-11-01

    Continental plateaux, such as the Tibetan Plateau in Asia and the Altiplano-Puna Plateau in South America, are thought to form partly because upwelling, hot asthenospheric mantle replaces some of the denser, lower lithosphere, making the region more buoyant. The spatial and temporal scales of this process are debated, with proposed mechanisms ranging from delamination of fragments to that of the entire lithosphere. The Canadian Cordillera is an exhumed ancient plateau that abuts the North American Craton. The region experienced rapid uplift during the mid-to-late Eocene, followed by voluminous magmatism, a transition from a compressional to extensional tectonic regime and removal of mafic lower crust. Here we use Rayleigh-wave tomographic and thermochronological data to show that these features can be explained by delamination of the entire lithosphere beneath the Canadian Cordillera. We show that the transition from the North American Craton to the plateau is marked by an abrupt reduction in lithospheric thickness by more than 150 km and that asthenosphere directly underlies the crust beneath the plateau region. We identify a 250-km-wide seismic anomaly about 150-250 km beneath the plateau that we interpret as a block of intact, delaminated lithosphere. We suggest that mantle material upwelling along the sharp craton edge triggered large-scale delamination of the lithosphere about 55 million years ago, and caused the plateau to uplift.

  6. Moho offsets beneath the Western Ghat and the contact of Archean crusts of Dharwar Craton, India

    NASA Astrophysics Data System (ADS)

    Saikia, Utpal; Rai, S. S.; Meena, Rishikesh; Prasad, B. N. V.; Borah, Kajaljyoti

    2016-03-01

    We present the Moho depth variation along a 600 km long profile from the west to the east coast of South India covering the passive continental margin, and the Western Ghat escarpment created during India-Madagascar separation at ~ 85 Ma; Archean western and eastern Dharwar Craton, and Proterozoic basin. The image is generated through three different approaches: H - vP/vS stacking, common conversion point (CCP) migration and inversion of teleseismic receiver functions at 38 locations. The Moho depth along the profile varies smoothly between 34 and 41 km, except beneath the Western Ghat and at the contact of east and west Dharwar Craton, where it is offset by up to ~ 8 km. The study suggests (i) the possible differential uplift of the Western Ghat, as a consequence of India-Madagascar separation and the prominent role of deep crustal structure in the location of the escarpment, compared to the surface process and (ii) presence of long-lived steeply dipping fault separating the two distinct Archean crustal blocks indicative of mechanically strong continental lithosphere beneath the Dharwar Craton.

  7. Altered morphology, nuclear stability and adhesion of highly metastatic derivatives of osteoblast-like SAOS-2 osteosarcoma cells.

    PubMed

    Muff, Roman; Nigg, Natalie; Gruber, Philipp; Walters, Denise; Born, Walter; Fuchs, Bruno

    2007-01-01

    Metastasis is the leading cause of death in patients with osteosarcoma (OS). High alkaline phosphatase (ALP) activity and resistance to chemotherapy are independent predictors of poor clinical outcome of osteosarcoma. Here, the osteoblastic phenotype, cell and nuclear morphology, cell adhesion and drug resistance of the SAOS-2 cell line and two in vivo selected highly metastatic derivatives, LM5 and LM7, were compared. ALP activity and deposition of mineralized extracellular matrix were the same in the parental SAOS-2 and the LM5 and LM7 cells, but parathyroid hormone (PTH)-stimulated cAMP accumulation was lost in the LM7 cells. The LM5 and LM7 cells were smaller than the parental SAOS-2 cells, and 10% of the LM7 cells had distorted nuclei. The adhesion of LM5 and LM7 cells was decreased when compared to SAOS-2 cells. The cytotoxic responses of the SAOS-2, LM5 and LM7 cells to Cisplatin, Doxorubicin and Etoposide were indistinguishable. The increased metastatic potential of LM5 and LM7 as compared to SAOS-2 cells is not associated with a substantial change of the osteoblastic phenotype or of the cytotoxic response to current chemotherapeutic drugs. The decrease in cell size and altered cell adhesion, reflecting cytoskeletal rearrangement, together with increased nuclear instability and partial dedifferentiation, as revealed by the loss of PTH responsiveness in LM7 cells, may account for the higher metastatic potential of the LM5 and LM7 sublines as compared to the parental SAOS-2 cells.

  8. Phanerozoic deposition, erosion, and vertical motion history of the Slave craton from apatite (U-Th)/He thermochronometry

    NASA Astrophysics Data System (ADS)

    Ault, A. K.; Flowers, R. M.; Bowring, S. A.

    2012-12-01

    Resolving the history and causes of elevation change in cratonic settings is a challenging problem. We integrate apatite (U-Th)/He thermochronometry (AHe) data and geologic observations to constrain the Phanerozoic burial, unroofing, and hypsometric evolution of the Archean Slave craton and surrounding Proterozoic belts in the northwestern Canadian shield. Although the craton currently lacks Phanerozoic strata, Phanerozoic sedimentary xenoliths contained within kimberlites of different ages demonstrate that such rocks once covered the craton. The thermochronometry data allow us to constrain the spatial extent, thickness, and history of these now-denuded sedimentary units. New AHe results consist of 94 apatite analyses for 16 samples and, together with previously published data, yield one of the largest published cratonic AHe datasets. AHe dates range from 210 ± 12 Ma to 363 ± 37 Ma. Dates are older in the eastern Slave craton and decrease to the west. Thermal history simulations are consistent with Paleozoic heating to temperatures ≥88-90 °C, suggesting burial beneath ≥3.5 km of sedimentary rocks across the region, followed by cooling and unroofing that progressed from east to west. Model results also permit heating in Cretaceous time, consistent with burial to ≤1.3 km and subsequent unroofing. When combined with other AHe datasets, regional unconformities, and sedimentary xenolith data, the results show that an episode of Paleozoic-early Mesozoic burial and unroofing affected most of the western Canadian shield. This history is out of sequence with sea level chronologies and demands Paleozoic subsidence of the craton followed by surface uplift. The Slave craton subsequently underwent at least 300 m of post-100 Ma elevation gain, based on ca. 100 Ma marine sedimentary xenoliths entrained in ~75-45 Ma kimberlites of the central Slave craton at modern 500-600 m elevations. Comparison of this hypsometric history with far-field plate boundary activity suggests

  9. The Health, Mobility & Safety Lab at San Francisco State University.

    ERIC Educational Resources Information Center

    Yee, Darlene; Melichar, Joseph F.

    The purpose of this research project at San Francisco State University was to develop and evaluate integrated assessment and intervention strategies to locate the "at risk" older driver and remediate deficits in knowledge or skills about driving and traffic safety. The identification of the "at risk" older driver should suggest…

  10. Helical grip for the cable cars of San Francisco

    NASA Technical Reports Server (NTRS)

    Peyran, R. J.

    1979-01-01

    A helical cable car grip to minimize high maintenance costs of San Francisco's cable car operation is presented. The grip establishes a rolling contact between the cable and grip to reduce sliding friction and associated cable wear. The design, development, and testing of the helical cable car grip are described.

  11. Cultural Factors Related to Smoking in San Francisco's Irish Bars

    ERIC Educational Resources Information Center

    Satterlund, Travis D.; Antin, Tamar M. J.; Lee, Juliet P.; Moore, Roland S.

    2009-01-01

    California's Smoke-Free Workplace Act was extended to include bars in 1998. While the majority of bars in the state have become smoke free, in many bars patrons and staff continue to smoke despite the law. The authors present findings from a study which assessed cultural factors related to continued smoking in bars in the city of San Francisco. In…

  12. VIEW OF PELTON WATER WHEEL COMPANY (SAN FRANCISCO) TURBINE: SPEED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF PELTON WATER WHEEL COMPANY (SAN FRANCISCO) TURBINE: SPEED 225 RPM, 17,500 HP. PHOTO BY JET LOWE, HAER, 1995. (Note: the dark hole in the concrete column to the left is from a tear in the negative.) - Elwha River Hydroelectric System, Glines Hydroelectric Dam & Plant, Port Angeles, Clallam County, WA

  13. A Water Quality Study: Heron's Head Park, San Francisco, California

    NASA Astrophysics Data System (ADS)

    Li, A.; Wu, K.; Neiss, J.

    2007-12-01

    Heron's Head Park, formerly known as Pier 98, is a 24-acre restored wetland, owned and operated by the Port of San Francisco and situated at the base of the Hunter's Point Power Plant. Heron's Head is a unique environment that is built on landfill and is now a thriving marsh maintained primarily by youth and community volunteers. Adjacent to the park stands a PG&E power plant (closed May 2006), a county waste transfer station, and a combined sewer overflow (CSO) pipe. The park is bordered by San Francisco Bay on the north, east and south sides of the park. We examined the levels of ammonia, nitrite, nitrate, phosphate and fecal coliform at nine sites around the park. Utilizing historical data from other San Francisco Bay sites and other similar estuarine settings in California, we assessed the health of the Bay waters surrounding the park. We found the levels of ammonia, nitrate, nitrite and phosphates to be within the parameters of historical San Francisco Bay data and similar to settings such as Elkhorn Slough, Tomales Bay and Tijuana Estuary. In our study we did find a potential hazard to human health. Fecal coliform concentrations in waters that border the park range from 340 MPN/100 mL - 24,000 MPN/100 mL. This level significantly exceeds Environmental Protection Agency recommendations of 300 MPN/100 mL for human contact with water.

  14. Cultural Factors Related to Smoking in San Francisco's Irish Bars

    ERIC Educational Resources Information Center

    Satterlund, Travis D.; Antin, Tamar M. J.; Lee, Juliet P.; Moore, Roland S.

    2009-01-01

    California's Smoke-Free Workplace Act was extended to include bars in 1998. While the majority of bars in the state have become smoke free, in many bars patrons and staff continue to smoke despite the law. The authors present findings from a study which assessed cultural factors related to continued smoking in bars in the city of San Francisco. In…

  15. Ethnicity and Phonetic Variation in a San Francisco Neighborhood

    ERIC Educational Resources Information Center

    Hall-Lew, Lauren

    2009-01-01

    This dissertation advances research in sociolinguistics by analyzing phonetic variation in a majority Asian American community in San Francisco, California. As one of the first community studies focusing on Asian Americans in an urban US context, this work speaks to ongoing discussions about speaker ethnicity, phonetic variation, and regional…

  16. Late Holocene Marsh Expansion in Southern San Francisco Bay, California

    EPA Science Inventory

    Currently, the largest tidal wetlands restoration project on the US Pacific Coast is being planned and implemented in southern San Francisco Bay; however, knowledge of baseline conditions of salt marsh extent in the region prior to European settlement is limited. Here, analysis o...

  17. Working Paper for the Revision of San Francisco's Cable Franchise.

    ERIC Educational Resources Information Center

    San Francisco Public Library, CA. Video Task Force.

    Ideas are presented for the revision of San Francisco's cable franchise. The recommendations in the report are based upon national research of library and urban use of cable communications and are designed to help the city's present and future cable franchises to comply with the regulations of the Federal Communications Commission by March 31,…

  18. Observations from moored current meters in San Francisco Bay, 1978

    USGS Publications Warehouse

    Gartner, Jeffrey W.; Cheng, Ralph T.

    1981-01-01

    Current-meter data collected at eight stations in the San Francisco Bay estuarine system between August 1978 and December 1978 are compiled in this report. The measurements include current speed and direction, and water temperature and salinity (computed from conductivity and temperature). Data are presented in graphical format with each parameter plotted separately.

  19. 33 CFR 161.50 - Vessel Traffic Service San Francisco.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vessel Traffic Service San... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY VESSEL TRAFFIC MANAGEMENT Vessel Traffic Service and Vessel Movement Reporting System Areas and Reporting Points § 161.50 Vessel Traffic Service San Francisco. The VTS...

  20. 33 CFR 161.50 - Vessel Traffic Service San Francisco.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Vessel Traffic Service San... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY VESSEL TRAFFIC MANAGEMENT Vessel Traffic Service and Vessel Movement Reporting System Areas and Reporting Points § 161.50 Vessel Traffic Service San Francisco. The VTS...

  1. 33 CFR 161.50 - Vessel Traffic Service San Francisco.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Vessel Traffic Service San... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY VESSEL TRAFFIC MANAGEMENT Vessel Traffic Service and Vessel Movement Reporting System Areas and Reporting Points § 161.50 Vessel Traffic Service San Francisco. The VTS...

  2. 33 CFR 161.50 - Vessel Traffic Service San Francisco.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Vessel Traffic Service San... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY VESSEL TRAFFIC MANAGEMENT Vessel Traffic Service and Vessel Movement Reporting System Areas and Reporting Points § 161.50 Vessel Traffic Service San Francisco. The VTS...

  3. 33 CFR 161.50 - Vessel Traffic Service San Francisco.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Vessel Traffic Service San... SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY VESSEL TRAFFIC MANAGEMENT Vessel Traffic Service and Vessel Movement Reporting System Areas and Reporting Points § 161.50 Vessel Traffic Service San Francisco. The VTS...

  4. Solar for Your Present Home. San Francisco Bay Area Edition.

    ERIC Educational Resources Information Center

    Barnaby, Charles S.; And Others

    This publication provides information about present uses of solar energy for space, water, and swimming pool heating that are practical for the San Francisco Bay area. It attempts to provide interested persons with the information needed to make decisions regarding installations of solar heating systems. The point of view taken is that any…

  5. Ethnicity and Phonetic Variation in a San Francisco Neighborhood

    ERIC Educational Resources Information Center

    Hall-Lew, Lauren

    2009-01-01

    This dissertation advances research in sociolinguistics by analyzing phonetic variation in a majority Asian American community in San Francisco, California. As one of the first community studies focusing on Asian Americans in an urban US context, this work speaks to ongoing discussions about speaker ethnicity, phonetic variation, and regional…

  6. Late Holocene Marsh Expansion in Southern San Francisco Bay, California

    EPA Science Inventory

    Currently, the largest tidal wetlands restoration project on the US Pacific Coast is being planned and implemented in southern San Francisco Bay; however, knowledge of baseline conditions of salt marsh extent in the region prior to European settlement is limited. Here, analysis o...

  7. San Francisco Bay Water Quality Improvement Fund RFP Webinar Registration

    EPA Pesticide Factsheets

    EPA Region 9 is hosting a free webinar to provide a detailed review of the FY 2017 San Francisco Bay Water Quality Improvement Fund RFP and help answer your proposal submittal questions.Date: Thursday, April 20, 2017Time: 2 PM – 3:30 PM Pacific

  8. 1906 Letter to the San Francisco Health Department

    ERIC Educational Resources Information Center

    Schmachtenberg, Kristin

    2006-01-01

    On Wednesday, April 18, 1906, an earthquake, measuring 7.8 on the Richter magnitude scale and lasting 48 seconds, erupted along the San Andreas fault with a flash point originating in the San Francisco Bay area. The force of the earthquake tore apart buildings and roads, causing water and gas mains to twist and break. The resulting effects of the…

  9. Francisco Martinez de Castrillo: An Early Spanish Author.

    PubMed

    Castro-Nunez, Jaime

    Francisco Martinez de Castrillo was a pioneer Spanish dental author who wrote and published Coloquio Breve y Compendioso Sobre la Materia de la Dentadura y Maravillosa Obra de la Boca, the first book published ever in the Spanish language. However, his life and work is largely unknown to the history of the dental profession. Copyright American Academy of the History of Dentistry.

  10. The San Francisco Joint Institutional Transportation Systems Management Program.

    ERIC Educational Resources Information Center

    Fink, Ira; LaPointe, Robert

    1981-01-01

    Transportation systems management (TSM) programs are discussed, particularly the 1977 program of the University of California, San Francisco, which led to traffic reduction and improved vehicle flow. The city's implementation plan for a similar TSM program for 14 educational institutions and hospitals is described. (MLW)

  11. 1906 Letter to the San Francisco Health Department

    ERIC Educational Resources Information Center

    Schmachtenberg, Kristin

    2006-01-01

    On Wednesday, April 18, 1906, an earthquake, measuring 7.8 on the Richter magnitude scale and lasting 48 seconds, erupted along the San Andreas fault with a flash point originating in the San Francisco Bay area. The force of the earthquake tore apart buildings and roads, causing water and gas mains to twist and break. The resulting effects of the…

  12. Solar for Your Present Home. San Francisco Bay Area Edition.

    ERIC Educational Resources Information Center

    Barnaby, Charles S.; And Others

    This publication provides information about present uses of solar energy for space, water, and swimming pool heating that are practical for the San Francisco Bay area. It attempts to provide interested persons with the information needed to make decisions regarding installations of solar heating systems. The point of view taken is that any…

  13. Students on Academic Probation at City College of San Francisco.

    ERIC Educational Resources Information Center

    City Coll. of San Francisco, CA. Office of Institutional Research, Planning and Grants.

    This document discusses students on academic probation in City College of San Francisco as of Spring 2002. During any given semester, 9-10% of students are on academic probation. A majority of students on academic probation are men. Higher numbers of African American (17%) and Filipino (17%) students were on academic probation rather than Whites…

  14. San Francisco Bay test case for 3-D model verification

    USGS Publications Warehouse

    Smith, Peter E.

    1994-01-01

    This paper describes a field test case for 3-D hydrodynamic model verification using data from Carquinez Strait in San Francisco Bay, California. It will be disseminated by the ASCE Computational Hydraulics task committee on 3-D Free-Surface Hydrodynamic Model Verifications during late 1994.

  15. Auckland--New Zealand's Los Angeles or San Francisco?

    ERIC Educational Resources Information Center

    Bogunovich, Dushko

    1995-01-01

    Compares Auckland (New Zealand) with San Francisco (California) in terms of topographical structure, geographic location, and urban development. Both cities contain striking similarities. Maintains that Auckland can become a world-class city renowned for its beauty if developers and government work in tandem. (MJP)

  16. Observations from remote weather stations in San Francisco Bay, California

    USGS Publications Warehouse

    Gartner, J.W.; Cheng, R.T.

    1983-01-01

    Weather data collected at three remote weather stations in the San Francisco Bay estuarine system between November 1979 and September 1981 are compiled in this report. Measurements include average and maximum wind speed, wind direction, air temperature, atmospheric pressure, and irradiance. Data are presented in time-series plots with each graph covering one calendar month. Daily averages of all measurements are tabulated.

  17. Asian American Students: A Look at San Francisco State.

    ERIC Educational Resources Information Center

    Okutsu, James K.

    The attitudes of American Asian students at San Francisco State University toward their education were studied. Responses were obtained from 585 students who were enrolled in Asian American Studies classes in spring 1986. Sixty percent of the sample were of Chinese ancestry, 20% were Filipino, and 20% were other Asian (including Japanese, Korean,…

  18. 76 FR 19519 - Intent To Prepare an Environmental Impact Statement for the Downtown San Francisco Ferry Terminal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-07

    ... Francisco Ferry Terminal Expansion Project in the City and County of San Francisco, CA AGENCY: Federal... Downtown San Francisco Ferry Terminal at the Port of San Francisco Ferry Building. The proposed project.... The project expands the number of ferry gates and improves ferry patron circulation, boarding, and...

  19. Seismic Tomography of the Arctic: Continental Cratons, Ancient Orogens, Oceanic Lithosphere and Convecting Mantle Beneath (Invited)

    NASA Astrophysics Data System (ADS)

    Lebedev, S.; Schaeffer, A. J.

    2013-12-01

    Lateral variations in seismic velocities in the upper mantle, mapped by seismic tomography, reflect primarily the variations in the temperature of the rock at depth. Seismic tomography thus reveals lateral changes in the temperature and thickness of the lithosphere; it maps deep boundaries between tectonic blocks with different properties and with different age of the lithosphere. Our new global, shear-wave tomographic model of the upper mantle and the crust is constrained by an unprecedentedly large number of broadband waveform fits (nearly one million seismograms, with both surface and S waves included) and provides improved resolution of the lithosphere across the whole of the Arctic region, compared to other available models. The most prominent high-velocity anomalies, seen down to 150-200 km depths, indicate the cold, thick, stable mantle lithosphere beneath Precambrian cratons. The northern boundaries of the Canadian Shield's and Greenland's cratonic lithosphere closely follow the coastlines, with the Greenland and North American cratons clearly separated from each other. In Eurasia, in contrast, cratonic lithosphere extends hundreds of kilometres north of the coast of the continent, beneath the Barents and eastern Kara Seas. The boundaries of the Archean cratons mapped by tomography indicate the likely offshore extensions of major Phanerozoic sutures in northern Eurasia. The old oceanic lithosphere of the Canada Basin is much colder and thicker than the younger lithosphere beneath the adjacent Amundsen Basin, north of the Gakkel Ridge. Beneath the slow-spreading Gakkel Ridge, we detect the expected low-velocity anomaly associated with partial melting in the uppermost mantle; the anomaly is weaker, however, than beneath faster-spreading ridges globally. South of the ridge, the Nansen Basin shows higher seismic velocities in the upper mantle beneath it, compared to the Amundsen Basin. At 150-250 km depth, most of the oceanic portions of the central Arctic (the

  20. Aeromagnetic interpretation in the south-central Zimbabwe Craton: (reappraisal of) crustal structure and tectonic implications

    NASA Astrophysics Data System (ADS)

    Ranganai, Rubeni T.; Whaler, Kathryn A.; Ebinger, Cynthia J.

    2016-11-01

    Regional aeromagnetic data from the south-central Zimbabwe Craton have been digitally processed and enhanced for geological and structural mapping and tectonic interpretation integrated with gravity data, to constrain previous interpretations based on tentative geologic maps and provide new information to link these structural features to known tectonic events. The derived maps show excellent correlation between magnetic anomalies and the known geology, and extend lithological and structural mapping to the shallow/near subsurface. In particular, they reveal the presence of discrete crustal domains and several previously unrecognised dykes, faults, and ultramafic intrusions, as well as extensions to others. Five regional structural directions (ENE, NNE, NNW, NW, and WNW) are identified and associated with trends of geological units and cross-cutting structures. The magnetic lineament patterns cut across the >2.7 Ga greenstone belts, which are shown by gravity data to be restricted to the uppermost 10 km of the crust. Therefore, the greenstone belts were an integral part of the lithosphere before much of the upper crustal (brittle) deformation occurred. Significantly, the observed magnetic trends have representatives craton-wide, implying that our interpretation and inferences can be applied to the rest of the craton with confidence. Geological-tectonic correlation suggests that the interpreted regional trends are mainly 2.5 Ga (Great Dyke age) and younger, and relate to tectonic events including the reactivation of the Limpopo Belt at 2.0 Ga and the major regional igneous/dyking events at 1.8-2.0 Ga (Mashonaland), 1.1 Ga (Umkondo), and 180 Ma (Karoo). Thus, their origin is here inferred to be inter- and intra-cratonic collisions and block movements involving the Zimbabwe and Kaapvaal Cratons and the Limpopo Belt, and later lithospheric heating and extension associated with the break-up of Gondwana. The movements produced structures, or reactivated older fractures