Insights into crustal assimilation by Icelandic basalts from boron isotopes in melt inclusions from the 1783–1784 Lakagígar eruption

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 94 (2012): 164-180, doi:10.1016/j.gca.2012.07.002.The boron isotope system has great potential for tracing alteration and assimilation in basaltic systems due to the very low concentrations of B in mantle-derived melts and the strong isotopic contrast between the mantle and surface materials. However, variability in B concentrations and isotope ratios in basalts can also be interpreted to reflect inputs from enriched regions of the mantle, as the extent of mantle heterogeneity with respect to boron remains poorly delineated. We have determined boron concentrations and isotope ratios in fresh, glassy, plagioclase-hosted melt inclusions and unaltered scoriaceous matrix glasses from four localities associated with the 1783-1784 Lakagígar (Laki Fissure) eruption, Iceland. Boron concentrations range from 0.59-1.25 ppm in the melt inclusions, and from 1.25-1.65 ppm in the matrix glasses, while δ11BNBS-951 ranges from - 7.8‰ to -16.5‰ in the melt inclusions and -10.5‰ to -16.9‰ in the matrix glasses. In contrast to previous studies of boron in basaltic melt inclusions from other fissure swarms in Iceland (Gurenko and Chaussidon, 1997, Chem. Geol. 135, 21-34), the Lakagígar melt inclusions display a significant range of boron concentrations and isotope ratios at constant K2O wt.%, which is more consistent with B addition by assimilation of altered basalt than it is with mixing between depleted and enriched mantle sources. Assimilation of freshwater-altered crustal materials at depth may impart a light δ11B signature such as that observed in the Lakagígar melt inclusions and tephra host glasses. Considering boron concentrations and isotope ratios in the Lakagígar glasses and previously studied altered Icelandic basalts, together with volatile equilibration depths of the Lakagígar melt inclusions, we propose that a) mantle-derived magmas formed beneath Lakagígar assimilated ~5-20% altered crust at a depth of ~3-4 km or more, probably during magma accumulation in sills formed at the boundaries of low-density hyaloclastite layers; and b) the magma subsequently underwent extensive mixing and homogenization prior to eruption, quite possibly within the magma chamber beneath the Grímsvötn central volcano, assimilating an additional ~10% of altered crust at that time, for a total of up to 30% crustal assimilation. We hypothesize that volatiles including H2O, CO2, S, F, and Cl, which were responsible for the majority of the considerable casualties attributed to the Lakagígar eruption, were added together with isotopically light B by assimilation of hydrothermally altered crustal materials.This work was supported by a PSU-EMS Miller Award to MDF, NSF 761 EAR 09117456 to PCL, and awards to MNB by the GSA Northeast Division Grant for Undergraduate Research, the Dept. of Geosciences Undergraduate Senior Thesis Grant, and PSU Undergraduate Research Discovery Grant

Chemistry of hot springs along the Eastern Lau Spreading Center

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 75 (2011): 1013-1038, doi:10.1016/j.gca.2010.12.008.The Eastern Lau Spreading Center (ELSC) is the southernmost part of the back-arc spreading axis in the Lau Basin, west of the Tonga trench and the active Tofua volcanic arc. Over its 397-km length it exhibits large and systematic changes in spreading rate, magmatic/tectonic processes, and proximity to the volcanic arc. In 2005 we collected 81 samples of vent water from six hydrothermal fields along the ELSC. The chemistry of these waters varies both within and between vent fields, in response to changes in substrate composition, temperature and pressure, pH, water/rock ratio, and input from magmatic gases and subducted sediment. Hot-spring temperatures range from 229º to 363ºC at the five northernmost fields, with a general decrease to the south that is reversed at the Mariner field. The southernmost field, Vai Lili, emitted water at up to 334°C in 1989 but had a maximum venting temperature of only 121ºC in 2005, due to waning activity and admixture of bottom seawater into the subseafloor plumbing system. Chloride varies both within fields and from one field to another, from a low of 528 mmol/kg to a high of 656 mmol/kg, and may be enriched by phase separation and/or leaching of Cl from the rock. Concentrations of the soluble elements K, Rb, Cs, and B likewise increase southward as the volcanic substrate becomes more silica-rich, especially on the Valu Fa Ridge. Iodine and δ7Li increase southward, and δ11B decreases as B increases, apparently in response to increased input from subducted sediment as the arc is approached. Species that decrease southward as temperature falls are Si, H2S, Li, Na/Cl, Fe, Mn, and 87Sr/86Sr, whereas pH, alkalinity, Ca, and Sr increase. Oxygen isotopes indicate a higher water/rock ratio in the three systems on Valu Fa Ridge, consistent with higher porosity in more felsic volcanic rocks. Vent waters at the Mariner vent field on the Valu Fa Ridge are significantly hotter, more acid and metal-rich, less saline, and richer in dissolved gases and other volatiles, including H2S, CO2, and F, than the other vent fields, consistent with input of magmatic gases. The large variations in geologic and geophysical parameters produced by back-arc spreading along the ELSC, which exceed those along mid-ocean ridge spreading axes, produce similar large variations in the composition of vent waters, and thus provide new insights into the processes that control the chemistry of submarine hot springs.We thank the U.S. National Science Foundation and its RIDGE 2000 Program for funding this study via grants OCE0241826 (to MJM), OCE0242902 (to PJM), OCE0241796 (to JSS, MKT), and OCE0242088 (to CGW), as well as the Deep Ocean Exploration Institute at WHOI (to GP, ER)

Do genetic factors protect for early onset lung cancer? A case control study before the age of 50 years

<p>Abstract</p> <p>Background</p> <p>Early onset lung cancer shows some familial aggregation, pointing to a genetic predisposition. This study was set up to investigate the role of candidate genes in the susceptibility to lung cancer patients younger than 51 years at diagnosis.</p> <p>Methods</p> <p>246 patients with a primary, histologically or cytologically confirmed neoplasm, recruited from 2000 to 2003 in major lung clinics across Germany, were matched to 223 unrelated healthy controls. 11 single nucleotide polymorphisms of genes with reported associations to lung cancer have been genotyped.</p> <p>Results</p> <p>Genetic associations or gene-smoking interactions was found for <it>GPX1(Pro200Leu) </it>and <it>EPHX1(His113Tyr)</it>. Carriers of the Leu-allele of <it>GPX1(Pro200Leu) </it>showed a significant risk reduction of OR = 0.6 (95% CI: 0.4–0.8, p = 0.002) in general and of OR = 0.3 (95% CI:0.1–0.8, p = 0.012) within heavy smokers. We could also find a risk decreasing genetic effect for His-carriers of <it>EPHX1(His113Tyr) </it>for moderate smokers (OR = 0.2, 95% CI:0.1–0.7, p = 0.012). Considered both variants together, a monotone decrease of the OR was found for smokers (OR of 0.20; 95% CI: 0.07–0.60) for each protective allele.</p> <p>Conclusion</p> <p>Smoking is the most important risk factor for young lung cancer patients. However, this study provides some support for the T-Allel of <it>GPX1(Pro200Leu) </it>and the C-Allele of <it>EPHX1(His113Tyr) </it>to play a protective role in early onset lung cancer susceptibility.</p

Alternative Presents for Dynamic Fabric

In this paper we investigate how a combination of "speculative" design methods can be used to generate theoretical understandings for dynamic, colour-changing fabrics for garments. Specifically, we combine a first-person, autobiographical, research through design (RtD) approach that draws strategies from speculative design. We call this approach alternative presents, inspired by the work of James Auger, and explore it as a way to generate theoretical propositions for dynamic fabric that emphasize the lived experience over technological innovation. The contributions of this framing are twofold. Firstly, we offer a theoretical contribution to the literature on dynamic fabric. Secondly, we make a methodological contribution for how autobiographical design and RtD can be oriented speculatively to generate intermediate knowledge, with particular emphasis on social-technical aspects

Medline database for Mass College of Pharmacy

This project examines the process by which a new patient tracking system for MassMedline was developed. It encompasses the four critical steps to this process: a comprehensive literature review, analysis of the "as-is" system including a feasibility study for implementing a new system, design of the new system and finally implementation of the new system. The new system developed includes a relational database contained in Microsoft Access which is accessed through client programs written in Visual Basic 6.0

Expanding the Princeton, MA, wind farm.

This project examines the potential for expansion of the Princeton, MA., wind farm. It encompasses the four critical aspects of an expansion: wind resource verification, turbine selection and placement, environmental impact and public perception. The findings are that there is enough wind at the site to support wind turbines, and that the best layout is two 1,000 kw turbines placed along the north and south edges of the site. Environmental and public perception issues require further research, but seem to be limited