11 results
Geochemistry of a high-T hydrothermal dolostone from the Emirli (Ödemiş, western Turkey) Sb-Au deposit
- M. Akçay, H. M. Özkan, B. Spiro, R. Wilson, P. W. O. Hoskin
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- Journal:
- Mineralogical Magazine / Volume 67 / Issue 4 / August 2003
- Published online by Cambridge University Press:
- 05 July 2018, pp. 671-688
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A dolostone layer is found in spatial association with the Emirli epithermal Sb-Au deposit in western Turkey. It occurs within an argillic alteration zone adjacent to the major Emirli fault zone, which is the controlling structure for the deposit, and is composed of large closely packed subhedral to anhedral planar and nonplanar dolomites. Pyrite is the only accessory mineral in the layer and occurs as disseminations and veinlets up to 100 μm wide. Dolomite crystals are petrographically homogeneous and have consistent deep-red cathodoluminescence (CL) colour with no zoning which implies single-stage dolomitization of a calcitic precursor which is partly preserved as remnant patches of orange-coloured CL zones. Some crystal boundaries have dark (or no) CL colour. Electron microprobe line-scan analyses across these regions indicate intense enrichment of Fe and Mg depletion, revealing late-stage Fe-metasomatism (ankeritization) especially prevalent near pyrite veinlets and disseminations.
Dolomite crystals are composed of 52.4–55.0 mol.% CaCO3, 29.9 –41.2 mol.% MgCO3, 1.8 – 14.4 mol.% FeCO3 and 0.75 –3.2 mol.% MnCO3 indicating ferroan dolomite. The relationship between Ca and Mg is not stoichiometric due to substitution of Mg2+ by Fe2+ after dolomitization, as demonstrated by a strong negative correlation between Fe and Mg. Whole-rock Fe contents of the dolostone layer increases toward the Emirli fault zone.
The δ13C(PDB) compositions of the Emirli dolomite, calcitic marbles, and graphite-schists are in the ranges of –1.6 to 0.8‰, 1.5 to 1.5‰ and –6.6 to –23.5%, respectively, indicating that dolomite was formed due to interaction of light-carbon-enriched fluids with calcitic marbles; light-carbon may have been derived from decarboxylation of the graphitic schist layers. δ18O(PDB) values of dolomite and marble range –15.2 to – 11.2‰ and –2.4 to – 3.5‰, respectively. This large isotopic difference between dolomite and marble was probably inherited from oxygen isotope exchange between the dolomitizing fluid and the precursor calcites, as well as other minerals enriched in light-oxygen.
Fluid inclusions in dolomite are two-phase, and homogenize into liquid within the temperature interval 242 – 362ºC with a mode of 290ºC, and have salinities of 1 – 3 wt.% NaCl equiv. Using this modal temperature, the average δ18O(PDB) composition of water in isotopic equilibrium with the Emirli dolostone was estimated to be –19.4±2.1‰, which is interpreted as an indication of modified surface-waters; this interpretation is also supported by low fluid salinity and Na and Sr contents. These fluids migrated along graben-related faults, penetrating deeper levels where they were transformed into hydrothermal fluids due to the high heat-flow of the Küçük Menderes graben system, and flowed-up mainly through the Emirli and Haliköy faults that control mineralization in local deposits of Sb-Au and Hg, respectively. Due to interaction with chlorite-bearing graphite-schists, the fluid may have dissolved Mg2+ from chlorite and been enriched in isotopically-light carbon due to decarboxylation of graphite. Dolomitization occurred as a result of the interaction of these fluids with a calcitic marble band adjacent to the Emirli fault zone. Subsequent introduction of Fe2+ caused ankeritization along dolomite crystal boundaries during first-stage Sb-Au mineralization.
Mineralogical and S isotopic features of the supergene profile of the Zapadno-Ozernoe massive sulphide and Au-bearing gossan deposit, South Urals
- E. V. Belogub, C. A. Novoselov, B. Spiro, B. A. Yakovleva
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- Journal:
- Mineralogical Magazine / Volume 67 / Issue 2 / April 2003
- Published online by Cambridge University Press:
- 05 July 2018, pp. 339-354
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The profile of the supergene zone of the Zapadno-Ozernoe massive sulphide Cu-Zn deposit differs from the classic model (Emmons, 1917) in that it includes a prominent dark sooty subzone rich in secondary sulphides. This subzone is situated above residual pyrite sands, which overlie the massive sulphide body and below quartz-baryte leached sands. It contains a diverse mineral assemblage which consists of secondary sulphides such as galena, sphalerite, metacinnabar, Se-bearing pyrite—dhzarkenite series, tiemannite, native Au, native S and native Se, and unidentified sulphosalts of Ag and Hg. The very light S isotope composition of the secondary sulphides (lowest values δ34S = —17.2‰ (VCDt) in comparison with primary pyrite ∼0‰ and baryte +18.4‰ is indicative of bacterial sulphate reduction. The overlying oxidized part of the supergene column contains minerals of the jarosite-beudantite- segnitite series. The maximum concentrations of Au, up to 150 ppm, occur in the lower part of the profile. The atypical structure, mineral assemblage and S isotope composition of the secondary sulphides in the dark layer of the supergene profile are indicative of particular geochemical conditions due to the existence of a stagnant water body that gave rise to intense bacterial activity, in turn controlled by fluctuations in the redox boundary.
Oxygen, carbon and strontium isotope study of the carbonatitic dolomite host of the Bayan Obo Fe-Nb-REE deposit, Inner Mongolia, N China
- M. J. Le Bas, B. Spiro, Yang Xueming
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- Journal:
- Mineralogical Magazine / Volume 61 / Issue 407 / August 1997
- Published online by Cambridge University Press:
- 05 July 2018, pp. 531-541
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The large Fe-Nb-REE deposit at Bayan Obo is hosted by a dolomite marble within the thrust complex of marbles, quartzites and slates that belongs to the Bayan Obo Formation of mid-Proterozoic age. The dolomite is either a dolomitized sedimentary limestone subsequently mineralized and tectonically thrust and folded, or a dolomite (or dolomitized) carbonatite intrusion with late-stage recrystallization and mineralization that has been subsequently tectonically deformed.
O and C isotope data indicate that the sedimentary limestones and dolomites of the Bayan Obo Formation, which occur in the thrust stack together with quartzites and slates, have values of δO c. +20 per mil (SMOW) and δC c. zero. In contrast, the coarser grained facies of the large (0.5 × 10 km) dolomite marble which hosts the REE ore body has δO per mil values between +8 and +12 and δC values between −5 and −3, whereas the finer-grained recrystallized and REE-mineralized dolomite marble which occurs close to the ore bodies has δO between +12 to +16 and δC between −4 and zero. 87Sr/86Sr data confirm this distinction: >0.710 for the sedimentary rocks and <0.704 for the coarse- and fine-grained dolomite marbles.
These data are taken to indicate that the large and coarse-grained dolomite was an igneous carbonatite (as borne out by its fenitic contact rocks and trace element geochemistry), and that the finer grained dolomite recrystallized under the influence of mineralizing solutions which entrained groundwater. The stratiform features in the coarse-grained dolomite that are evident in the field are interpreted as tectonic layering.
3 - Scientific teams and networks change the face of knowledge creation
- from Part I - Information, collaboration, innovation: the creative power of networks
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- By Uzzi B., Northwestern University, USA., Wuchty S., Northwestern Institute on Complex Systems (NICO), USA., Spiro J., INSEAD Organisational Behaviour, Singapore., Jones B. F., Northwestern University, USA.
- Edited by Balázs Vedres, Central European University, Budapest, Marco Scotti, Università degli Studi di Trento, Italy
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- Book:
- Networks in Social Policy Problems
- Published online:
- 05 September 2012
- Print publication:
- 23 August 2012, pp 47-59
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Summary
There is an acclaimed tradition in the history and sociology of science that emphasizes the role of the individual genius in scientific discovery (Merton, 1968; Bowler and Morus, 2005). This tradition focuses on the guiding contributions of solitary authors, such as Newton and Einstein, and can be seen broadly in the tendency to equate great ideas with particular names; for example: the Heisenberg uncertainty principle, Euclidean geometry, Nash equilibrium, and Kantian ethics. The role of individual contributions is also celebrated through science's award-granting institutions, like the Nobel Prize Foundation (English, 2005).
However, several studies have explored the evident shift in science from this individual-based model of scientific advance to a collaborative model. By building on classic work by Harriet Zuckerman and Robert K. Merton, many authors have established a rising propensity for teamwork in samples of several research fields; with some studies going back a century (Collins, 1998; Cronin et al., 2003; Merton, 1973a; Jones, 2005). For example, Derek de Solla Price examined the change in team size in chemistry from 1910 to 1960, forecasting that by 1980 zero percent of the papers would be written by solo authors (de Solla Price, 1963). According to our research, the mean team size for papers written in chemistry had grown to nearly 3.7 contributors by the year 2000. Recently, Adams et al. (2005) established that teamwork has been increasing over time across broader sets of fields among the most competitive U.S. research universities.
Contributors
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- By Aakash Agarwala, Linda S. Aglio, Rae M. Allain, Paul D. Allen, Houman Amirfarzan, Yasodananda Kumar Areti, Amit Asopa, Edwin G. Avery, Patricia R. Bachiller, Angela M. Bader, Rana Badr, Sibinka Bajic, David J. Baker, Sheila R. Barnett, Rena Beckerly, Lorenzo Berra, Walter Bethune, Sascha S. Beutler, Tarun Bhalla, Edward A. Bittner, Jonathan D. Bloom, Alina V. Bodas, Lina M. Bolanos-Diaz, Ruma R. Bose, Jan Boublik, John P. Broadnax, Jason C. Brookman, Meredith R. Brooks, Roland Brusseau, Ethan O. Bryson, Linda A. Bulich, Kenji Butterfield, William R. Camann, Denise M. Chan, Theresa S. Chang, Jonathan E. Charnin, Mark Chrostowski, Fred Cobey, Adam B. Collins, Mercedes A. Concepcion, Christopher W. Connor, Bronwyn Cooper, Jeffrey B. Cooper, Martha Cordoba-Amorocho, Stephen B. Corn, Darin J. Correll, Gregory J. Crosby, Lisa J. Crossley, Deborah J. Culley, Tomas Cvrk, Michael N. D'Ambra, Michael Decker, Daniel F. Dedrick, Mark Dershwitz, Francis X. Dillon, Pradeep Dinakar, Alimorad G. Djalali, D. John Doyle, Lambertus Drop, Ian F. Dunn, Theodore E. Dushane, Sunil Eappen, Thomas Edrich, Jesse M. Ehrenfeld, Jason M. Erlich, Lucinda L. Everett, Elliott S. Farber, Khaldoun Faris, Eddy M. Feliz, Massimo Ferrigno, Richard S. Field, Michael G. Fitzsimons, Hugh L. Flanagan Jr., Vladimir Formanek, Amanda A. Fox, John A. Fox, Gyorgy Frendl, Tanja S. Frey, Samuel M. Galvagno Jr., Edward R. Garcia, Jonathan D. Gates, Cosmin Gauran, Brian J. Gelfand, Simon Gelman, Alexander C. Gerhart, Peter Gerner, Omid Ghalambor, Christopher J. Gilligan, Christian D. Gonzalez, Noah E. Gordon, William B. Gormley, Thomas J. Graetz, Wendy L. Gross, Amit Gupta, James P. Hardy, Seetharaman Hariharan, Miriam Harnett, Philip M. Hartigan, Joaquim M. Havens, Bishr Haydar, Stephen O. Heard, James L. Helstrom, David L. Hepner, McCallum R. Hoyt, Robert N. Jamison, Karinne Jervis, Stephanie B. Jones, Swaminathan Karthik, Richard M. Kaufman, Shubjeet Kaur, Lee A. Kearse Jr., John C. Keel, Scott D. Kelley, Albert H. Kim, Amy L. Kim, Grace Y. Kim, Robert J. Klickovich, Robert M. Knapp, Bhavani S. Kodali, Rahul Koka, Alina Lazar, Laura H. Leduc, Stanley Leeson, Lisa R. Leffert, Scott A. LeGrand, Patricio Leyton, J. Lance Lichtor, John Lin, Alvaro A. Macias, Karan Madan, Sohail K. Mahboobi, Devi Mahendran, Christine Mai, Sayeed Malek, S. Rao Mallampati, Thomas J. Mancuso, Ramon Martin, Matthew C. Martinez, J. A. Jeevendra Martyn, Kai Matthes, Tommaso Mauri, Mary Ellen McCann, Shannon S. McKenna, Dennis J. McNicholl, Abdel-Kader Mehio, Thor C. Milland, Tonya L. K. Miller, John D. Mitchell, K. Annette Mizuguchi, Naila Moghul, David R. Moss, Ross J. Musumeci, Naveen Nathan, Ju-Mei Ng, Liem C. Nguyen, Ervant Nishanian, Martina Nowak, Ala Nozari, Michael Nurok, Arti Ori, Rafael A. Ortega, Amy J. Ortman, David Oxman, Arvind Palanisamy, Carlo Pancaro, Lisbeth Lopez Pappas, Benjamin Parish, Samuel Park, Deborah S. Pederson, Beverly K. Philip, James H. Philip, Silvia Pivi, Stephen D. Pratt, Douglas E. Raines, Stephen L. Ratcliff, James P. Rathmell, J. Taylor Reed, Elizabeth M. Rickerson, Selwyn O. Rogers Jr., Thomas M. Romanelli, William H. Rosenblatt, Carl E. Rosow, Edgar L. Ross, J. Victor Ryckman, Mônica M. Sá Rêgo, Nicholas Sadovnikoff, Warren S. Sandberg, Annette Y. Schure, B. Scott Segal, Navil F. Sethna, Swapneel K. Shah, Shaheen F. Shaikh, Fred E. Shapiro, Torin D. Shear, Prem S. Shekar, Stanton K. Shernan, Naomi Shimizu, Douglas C. Shook, Kamal K. Sikka, Pankaj K. Sikka, David A. Silver, Jeffrey H. Silverstein, Emily A. Singer, Ken Solt, Spiro G. Spanakis, Wolfgang Steudel, Matthias Stopfkuchen-Evans, Michael P. Storey, Gary R. Strichartz, Balachundhar Subramaniam, Wariya Sukhupragarn, John Summers, Shine Sun, Eswar Sundar, Sugantha Sundar, Neelakantan Sunder, Faraz Syed, Usha B. Tedrow, Nelson L. Thaemert, George P. Topulos, Lawrence C. Tsen, Richard D. Urman, Charles A. Vacanti, Francis X. Vacanti, Joshua C. Vacanti, Assia Valovska, Ivan T. Valovski, Mary Ann Vann, Susan Vassallo, Anasuya Vasudevan, Kamen V. Vlassakov, Gian Paolo Volpato, Essi M. Vulli, J. Matthias Walz, Jingping Wang, James F. Watkins, Maxwell Weinmann, Sharon L. Wetherall, Mallory Williams, Sarah H. Wiser, Zhiling Xiong, Warren M. Zapol, Jie Zhou
- Edited by Charles Vacanti, Scott Segal, Pankaj Sikka, Richard Urman
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- Book:
- Essential Clinical Anesthesia
- Published online:
- 05 January 2012
- Print publication:
- 11 July 2011, pp xv-xxviii
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Contributors
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- By Giustino Albanese, Andrew Amaranto, Brandon H. Backlund, Alexander Baxter, Abraham Berger, Mark Bernstein, Marian E. Betz, Omar Bholat, Suzanne Bigelow, Carl Bonnett, Elizabeth Borock, Christopher B. Colwell, Alasdair Conn, Moira Davenport, David Dreitlein, Aaron Eberhardt, Ugo A. Ezenkwele, Diana Felton, Spiros G. Frangos, John E. Frank, Jonathan S. Gates, Lewis Goldfrank, Pinchas Halpern, Jean Hammel, Kristin E. Harkin, Jason S. Haukoos, E. Parker Hays, Aaron Hexdall, James F. Holmes, Debra Houry, Jennifer Isenhour, Andy Jagoda, John L. Kendall, Erica Kreisman, Nancy Kwon, Eric Legome, Matthew R. Levine, Phillip D. Levy, Charles Little, Marion Machado, Heather Mahoney, Vincent J. Markovchick, Nancy Martin, John Marx, Julie Mayglothling, Ron Medzon, Maurizio A. Miglietta, Elizabeth L. Mitchell, Ernest Moore, Maria E. Moreira, Sassan Naderi, Salvatore Pardo, Sajan Patel, David Peak, Christine Preblick, Niels K. Rathlev, Charles Ray, Phillip L. Rice, Carlo L. Rosen, Peter Rosen, Livia Santiago-Rosado, Tamara A. Scerpella, David Schwartz, Fred Severyn, Kaushal Shah, Lee W. Shockley, Mari Siegel, Matthew Simons, Michael Stern, D. Matthew Sullivan, Carrie D. Tibbles, Knox H. Todd, Shawn Ulrich, Neil Waldman, Kurt Whitaker, Stephen J. Wolf, Daniel Zlogar
- Edited by Eric Legome, Lee W. Shockley
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- Book:
- Trauma
- Published online:
- 07 September 2011
- Print publication:
- 16 June 2011, pp ix-xiv
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Nutrition-related patient safety incidents
- B. Holmes, A. Spiro, J. E. Thomas, K. Whelan, C. E. Weekes, C. Baldwin, P. W. Emery
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- Journal:
- Proceedings of the Nutrition Society / Volume 69 / Issue OCE7 / 2010
- Published online by Cambridge University Press:
- 08 April 2011, E529
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13C/12C of organisms from Juan de Fuca Ridge hydrothermal vents: a guide to carbon and food sources
- A.J. Southward, E.C. Southward, B. Spiro, G.H. Rau, V. Tunnicliffe
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- Journal:
- Journal of the Marine Biological Association of the United Kingdom / Volume 74 / Issue 2 / May 1994
- Published online by Cambridge University Press:
- 11 May 2009, pp. 265-278
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Soft tissue δ13C values were determined in vestimentiferan tube worms, alvinellid polychaetes and molluscs from Axial Seamount and Middle Valley, North-east Pacific. Inorganic carbon in mollusc shells and water samples was also analysed. In the vestimentiferan, Ridgeia piscesae, which lives in symbiosis with sulphur-oxidizing chemolithoautotrophic bacteria, tissue samples from the Axial vents showed δ13C values from −11 to −16‰, whereas at Middle Valley, where venting occurs through sediments, the δ13C ranged from −16 to −26‰. The tissues of an associated polychaete, Paralvinella palmiformis, which feeds on free-living bacteria, had δ13C values in the range −21 to −26‰. The bivalve Calyptogena from Middle Valley was more depleted than Ridgeia and Paralvinella, −37‰, closer to the ratios found in chemolithoautotrophic symbioses in non-vent habitats. Considerable, but variable, depletion (−23 to −42‰) was found in small gastropods. Mollusc shells and diluted vent water differed little in δ13C compared to inorganic carbon in ambient deep sea-water.
Late Proterozoic glacial carbonates in northeast Spitsbergen: new insights into the carbonate–tillite association
- I. J. Fairchild, M. J. Hambrey, B. Spiro, T. H. Jefferson
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- Journal:
- Geological Magazine / Volume 126 / Issue 5 / September 1989
- Published online by Cambridge University Press:
- 01 May 2009, pp. 469-490
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Carbonate-rich glacial deposits from two discrete Vendian glacial periods are described. The older is represented by the 24–40 m thick Petrovbreen Member (E2) of the Elbobreen Formation which contains abundant detrital dolomite. Clasts in E2 and their possible source rocks have positive δ13C and negative δ18OPDB values. In contrast the carbonate mud-fraction of E2 sediments has different cathodoluminescence characteristics from clasts, slightly negative δ13C values, and higher Fe and Mn concentrations than clasts. Oxygen isotopes vary from −2.5 to +4.5‰PDB, thought to be related to various seawater–meltwater mixtures in the depositional environment. Preservation of information about glacial sedimentary environments is attributed to early diagenetic recrystallization forced by excess surface free energy (Ostwald's ripening) and coinciding with sulphate reduction.
The younger glaciation is represented by the Wilsonbreen Formation (170 m) which has a distinctive glaciolacustrine Middle Carbonate Member (W2). W2 contains precipitated periglacial carbonates (with high Mn/Fe ratio): both limestone (rhythmitic and stromatolitic) and dolostone (rhythmites, stromatolites and dolomite-rich sandstones) which are compared with carbonates in modern Antarctic lakes. Evaporitic environments for dolomitic sandstones and stromatolitic dolostones are indicated by heavy oxygen isotope values (up to + 10.5‰PDB), high Na concentration and evidence for dissolved evaporites. High Mn concentration in detrital dolostones in W2 is suggestive of syn-sedimentary dolomite recrystallization in freshwater diamictites and haematitic siltstones.
The carbonate–tillite association ultimately arises from the erosion of underlying carbonates which originated (in this case) under radically different climatic conditions. Glacial depositional waters then became carbonate-saturated as a result of dissolution of detrital carbonate. Massive recrystallization of glacially transported carbonate is proposed as a geologically significant process with considerable potential for palaeoenvironmental analysis. In glacial lakes carbonate precipitated in response to evaporation or photosynthesis. Carbonate precipitation as the result of seawater freezing, or in warm interglacial conditions, is not yet established. Oxygen isotope value are inconsistent (too heavy) with the presence of high-latitude meltwaters, implying that glaciation extended to low latitudes as proposed by Harland.
13 - Reactive carbonate in glacial systems: a preliminary synthesis of its creation, dissolution and reincarnation
- Edited by M. Deynoux, J. M. G. Miller, Vanderbilt University, Tennessee, E. W. Domack, Hamilton College, New York, N. Eyles, University of Toronto, I. Fairchild, University of Birmingham, G. M. Young, University of Western Ontario
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- Book:
- Earth's Glacial Record
- Published online:
- 06 July 2010
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- 19 May 1994, pp 176-192
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Summary
Abstract
Subglacial transport of carbonate rock debris produces abundant fine reactive particles (rock flour) which are susceptible to dissolution. Longer transport distance and mixing with quartz increases rock flour formation, but the role of primary grain size and the quantity of the most reactive submicron-sized material is unclear. Considerations of equilibrium solubility indicate enhanced dissolution will occur in systems open to atmospheric CO2, or where acid production by pyrite oxidation is important, or where submicron-sized crystals are abundant. Kinetic considerations emphasize the increased reactivity of fine particles with freshly exposed surfaces and lattice defects, but dissolution is often limited by the sloth of reactions involving CO2. A number of processes can allow reprecipitation of calcite in the glacial system: ripening, warming, freezing, the common ion effect, removal of CO2 by organic or inorganic means, input of alkalinity from organic decomposition by bacteria, evaporation, transpiration and skeletal biomineralization. The relative importance of these mechanisms has yet to be established.
Examples of contemporary processes are discussed from ongoing work in Europe and North America. Meltwaters from carbonaterich glaciers are shown to have a wide variety of partial pressures of CO2 reflecting their complex processes of evolution; waters become supersaturated in response to evaporation, and to some extent degassing. Regelation crusts occur on clasts and are morphologically distinct from those in vadose proglacial areas. Evidence of Holocene modification of Pleistocene glacial sediments by calcrete formation and vadose cementation of gravels is presented from other sites.
The GALLEX Project
- T. Kirsten, M. Breitenbach, W. Hampel, G. Heusser, J. Kiko, T. Kirsten, H. Lalla, A. Lenzing, E. Pernicka, R. Plaga, B. Povh, C. Schlosser, H. Völk, R. Wink, K. Zuber, R.v. Ammon, K. Ebert, E. Henrich, L. Stieglitz, E. Bellotti, O. Cremonesi, E. Fiorini, C. Liguori, S. Ragazzi, L. Zanotti, R. Mössbauer, A. Urban, G. Berthomieu, E. Schatzman, S. d’Angelo, C. Bacci, P. Belli, R. Bernabei, L. Paoluzi, R. Santonico, M. Cribier, G. Dupont, B. Pichard, J. Rich, M. Spiro, T. Stolarczyk, C. Tao, D. Vignaud, I. Dostrovsky, G. Friedlander, R.L. Hahn, J.K. Rowley, R.W. Stoenner, J. Weneser
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- Journal:
- International Astronomical Union Colloquium / Volume 121 / 1990
- Published online by Cambridge University Press:
- 12 April 2016, pp. 187-199
- Print publication:
- 1990
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The GALLEX collaboration aims at the detection of solar neutrinos in a radiochemical experiment employing 30 tons of Gallium in form of concentrated aqueous Gallium-chloride solution. The detector is primarily sensitive to the otherwise inaccessible pp-neutrinos. Details of the experiment have been repeatedly described before [1-7]. Here we report the present status of implementation in the Laboratori Nazionali del Gran Sasso (Italy). So far, 12.2 tons of Gallium are at hand. The present status of development allows to start the first full scale run at the time when 30 tons of Gallium become available. This date is expected to be January, 1990.