26 research outputs found
Igneous Rock Associations 15. The Columbia River Basalt Group: A Flood Basalt Province in the Pacific Northwest, USA
The middle Miocene Columbia River Basalt Group (CRBG) is the youngest, smallest, and best-preserved continental flood-basalt province on Earth. The CRBG covers ~210,000 km2 of the Pacific Northwest, USA near the British Columbia border. CRBG consists of ~210,000 km3 of basalt that began erupting ~16.7 Ma in the southern part of the province with younger eruptions progressively migrating northward; the last eruption occurred at ~ 5 Ma. The CRBG consists of seven formations. The Steens Basalt is the oldest but the next oldest, the Imnaha Basalt, began erupting near the end of the Steens volcanic episode. After a short hiatus at the end of the Imnaha Basalt, the Grande Ronde Basalt began to erupt. Both the Picture Gorge Basalt and Prineville Basalt erupted simultaneously with the Grande Ronde Basalt. The Steens, Imnaha, and Grande Ronde Basalts are the main phase of the eruptions representing ~ 94% of the CRBG volume. The Wanapum Basalt followed the Grande Ronde Basalt, which in turn was followed by the Saddle Mountains Basalt, the final phase of the eruptions. The formations, members and many flows of the CRBG can be identified by using a combination of major, minor and trace element compositions, lithology, magnetic polarity, and stratigraphic position. This allows the aerial extent and volume of the individual flows and groups of flows to be calculated and correlated with their respective dykes and vents. The eruption and emplacement rate of the flows has been controversial, with various lines of evidence suggesting that some flows erupted very rapidly and others probably erupted over much longer periods of time. The CRBG was probably derived from a mantle plume, although this conclusion is controversial. Compositions indicate the CRBG magmas underwent varying degrees of recharge, contamination, and fractionation prior to each eruption. Although the peak eruptions occurred during the middle Miocene Climatic Optimum, at present no significant extinction or environmental consequence has been correlated with the CRBG.SOMMAIRELe Groupe de basaltes du fleuve Columbia (CRBG), du Miocène moyen, est la plus jeune, la plus petite et la mieux préservées des provinces de basaltes de plateau de la planète Terre. Le CRBG couvre une superficie d’environ 210 000 km2 dans la portion nord-ouest des États-Unis du Pacifique près de la frontière avec la Colombie-Britannique. Le CRBG, c’est environ 210 000 km3 de basaltes dont les premiers épanchements se sont produits il y a environ 16,7 Ma dans la portion sud de la province, les éruptions plus jeunes migrant progressivement vers le nord, la dernier s’étant produit il y a environ 5 Ma. Le CRBG est constitué de sept formations. La formation de basalte de Steens est le plus ancienne, mais la suivante, celle du basalte d’Imnaha est entrée en éruption près de la fin de l’épisode volcanique de Steens. Près une courte pause à la fin de l’épisode du basalte de la formation d'Imnaha, l’éruption du basalte de Grande Ronde a commencé. Et le basalte de Picture Gorge et le basalte de Prineville ont fait éruption en même temps que le basalte de Grande Ronde. Les basaltes de Steens, d’Imnaha, et de Grande Ronde forment la principale portion des éruptions avec environ 94% du volume du CRBG. Le basalte de Wanapum a succédé au basalte de la Grande Ronde, puis ce fut le basalte de Saddle Mountains, la phase finale des éruptions. Les formations, les membres et le nombre de coulées du CRBG peuvent être définis par analyse de leur composition en éléments majeurs, mineurs et traces, leur lithologie, leur polarité magnétique, et leur position stratigraphique. Ce qui permet d’estimer l’étendue et le volume de coulées individuelles, de groupes de coulées, et de les relier avec leur cheminée et dikes respectifs. Le taux des flux éruptifs ainsi que le leur mise en place ont été sujet à controverse étant donné que certaines indications suggèrent que certaines éruptions ont été très rapides alors que d'autres se seraient produites sur des périodes beaucoup plus longues. Le CRGB est probablement issus d’un panache mantellique, mais cela demeure controversé. Les compositions relevées indiquent que les magmas du CRBG ont subi à des degrés divers, des recharges, des contaminations et du fractionnement par cristallisation avant chaque éruption. Bien que les plus fortes éruptions se soient produites durant la période climatique optimum du Miocène moyen, jusqu’à présent, aucune extinction significative ou répercussion environnementale ont été mises en corrélation avec le CRBG
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Firms and markets that profit from investment in design and product development
This paper concerns a study which aimed to identify: (a) how returns from investments in design and product development vary with the types of market in which a firm operates; (b) the long-term benefits of investment in product design and innovation. The study built upon an earlier research project, which involved a survey of design and product development projects in 221 SMEs which had received some government support for design. This paper focuses on the results of a longitudinal, follow-up survey of a sample of 42 firms and projects, 8–9 years after the original study.
• The firms which had grown in turnover operated in growing markets and had typically developed innovative or niche products, while the declining firms generally operated in static or declining markets in which they had many competitors.
• The fast growing firms employed a statistically significantly higher proportion of RD&D staff; used external expertise for product development more often; and introduced new products more frequently, than the slow-growing or declining firms.
• All the growing firms had managers with a positive attitude towards design and innovation and increased their investment in RD&D during the recession, while most managers in the declining firms had a narrow and limited understanding of the contribution of design and reduced their investment.
• Since the earlier survey, performance, quality and price remain the key factors in product competition, although there is evidence of price and delivery becoming relatively more important – consistent with trends since the late 1980s in which firms increasingly have to compete on price and service as well as on product quality and design.
• SME managers and designers are now aware that multiple factors should be considered when designing a product but, given the differences in the commercial performance of the products, probably not all firms were equally effective in ensuring that these factors were actually taken into account.
These findings support previous research that business success and investment in design and product development are likely to be mutually reinforcing, while poor financial performance and a failure to invest can lead to a cycle of decline
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First Quarter Seismic Report for Fiscal Year 2006
This report describes the earthquake data collected from October 2005 to December 2005 from the Hanford Seismic Networ
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Fiscal Year 2006
This report summarizes the earthquake activity at the Hanford Site a vicinty that occurred during FY 200
Scaling of columnar joints in basalt
We describe field work, analysis, and modeling of columnar joints from the Columbia River Basalt Group. This work is focused on the regions around the Grand Coulee, Snake River, and Columbia Gorge, which form parts of this unusually homogeneous and very large sample of columnar basalt. We examine in detail the scaling relationship between the column width and the size of the striae and relate these quantitatively to thermal and fracture models. We found that the column radius and stria size are proportional to each other and inversely proportional to the cooling rate of the lava. Near a flow margin, our results put observational constraints on diffusive thermal models of joint formation. Deeper than a few meters into a colonnade, our measurements are consistent with a simple advection-diffusion model of two-phase convective cooling within the joints, regardless of the direction of cooling. This model allows an accurate comparison of igneous columnar jointing and joints due to desiccation in laboratory analog systems. We also identify a new length scale in which wavy columns can appear in some colonnades. The mechanisms leading to the wavy columns are likely related to those underlying similar wavy cracks in 2-D analog systems