ALBERT

Description / Table of Contents: Volatile components, by which we mean those magma constituents which typically prefer to occur in the gaseous or super-critical fluid state, may influence virtually every aspect of igneous petrology. The study of volatile-bearing systems, both in nature and in the laboratory, has far exceeded the relative abundances of these components in igneous rocks, yet in many ways the words of Bowen (1928) are still broadly applicable: " ... to many petrologists a volatile component is exactly like a Maxwell demon; it does just what one may wish it to do." (Bowen, 1928, p. 282) What we hope to show in this volume are some areas of progress in understanding the behavior of magmatic volatiles and their influence on a wide variety of geological phenomena; in doing this it also becomes apparent that there remain many questions outstanding. The range of topics we have tried to cover is broad, going from atomisticscale aspects of volatile solubility mechanisms and attendant effects on melt physical properties, to the chemistry of volcanic gases and the concentrations of volatiles in magmas, to the global geochemical cycles of volatiles. The reader should quickly see that much progress has been made since Bowen voiced his concerns about Maxwell demons, but like much scientific progress, answers to old questions have prompted even greater numbers of new questions. The Voltiles in Magmas course was organized and transpired at the Napa Valley Sheraton Hotel in California, December 2-4, 1994, just prior to the Fall Meetings of the American Geophysical Union in San Francisco.

Description / Table of Contents: A. C. Morton, R. S. Haszeldine, M. R. Giles, and S. Brown: Geology of the Brent Group: Introduction / Geological Society, London, Special Publications, 61:1-2, doi:10.1144/GSL.SP.1992.061.01.01 --- J. M. Bowen: Exploration of the Brent Province / Geological Society, London, Special Publications, 61:3-14, doi:10.1144/GSL.SP.1992.061.01.02 --- P. C. Richards: An introduction to the Brent Group: a literature review / Geological Society, London, Special Publications, 61:15-26, doi:10.1144/GSL.SP.1992.061.01.03 --- Graham Yielding, Michael E. Badley, and Alan M. Roberts: The structural evolution of the Brent Province / Geological Society, London, Special Publications, 61:27-43, doi:10.1144/GSL.SP.1992.061.01.04 --- B. C. Mitchener, D. A. Lawrence, M. A. Partington, M. B. J. Bowman, and J. Gluyas: Brent Group: sequence stratigraphy and regional implications / Geological Society, London, Special Publications, 61:45-80, doi:10.1144/GSL.SP.1992.061.01.05 --- S. J. C. Cannon, M. R. Giles, M. F. Whitaker, P. M. Please, and S. V. Martin: A regional reassessment of the Brent Group, UK sector, North Sea / Geological Society, London, Special Publications, 61:81-107, doi:10.1144/GSL.SP.1992.061.01.06 --- W. Helland-Hansen, M. Ashton, L. Lømo, and R. Steel: Advance and retreat of the Brent delta: recent contributions to the depositional model / Geological Society, London, Special Publications, 61:109-127, doi:10.1144/GSL.SP.1992.061.01.07 --- Elaine S. Scott: The palaeoenvironments and dynamics of the Rannoch—Etive nearshore and coastal succession, Brent Group, northern North Sea / Geological Society, London, Special Publications, 61:129-147, doi:10.1144/GSL.SP.1992.061.01.08 --- Jan Alexander: A discussion of alluvial sandstone body characteristics related to variations in marine influence, Middle Jurassic of the Cleveland Basin, UK, and the implications for analogous Brent Group strata in the North Sea Basin / Geological Society, London, Special Publications, 61:149-167, doi:10.1144/GSL.SP.1992.061.01.09 --- M. F. Whitaker, M. R. Giles, and S. J. C. Cannon: Palynological review of the Brent Group, UK sector, north sea / Geological Society, London, Special Publications, 61:169-202, doi:10.1144/GSL.SP.1992.061.01.10 --- Gwydion Williams: Palynology as a palaeoenvironmental indicator in the Brent Group, northern North Sea / Geological Society, London, Special Publications, 61:203-212, doi:10.1144/GSL.SP.1992.061.01.11 --- Euan W. Mearns: Samarium-neodymium isotopic constraints on the provenance of the Brent Group / Geological Society, London, Special Publications, 61:213-225, doi:10.1144/GSL.SP.1992.061.01.12 --- A. C. Morton: Provenance of Brent Group sandstones: heavy mineral constraints / Geological Society, London, Special Publications, 61:227-244, doi:10.1144/GSL.SP.1992.061.01.13 --- K. Stattegger and A. C. Morton: Statistical analysis of garnet compositions and lithostratigraphic correlation: Brent Group sandstones of the Oseberg Field, northern North Sea / Geological Society, London, Special Publications, 61:245-262, doi:10.1144/GSL.SP.1992.061.01.14 --- Knut Bjørlykke, Tor Nedkvitne, Mogens Ramm, and Girish C. Saigal: Diagenetic processes in the Brent Group (Middle Jurassic) reservoirs of the North Sea: an overview / Geological Society, London, Special Publications, 61:263-287, doi:10.1144/GSL.SP.1992.061.01.15 --- M. R. Giles, S. Stevenson, S. V. Martin, S. J. C. Cannon, P. J. Hamilton, J. D. Marshall, and G. M. Samways: The reservoir properties and diagenesis of the Brent Group: a regional perspective / Geological Society, London, Special Publications, 61:289-327, doi:10.1144/GSL.SP.1992.061.01.16 --- J. Reed Glasmann: The fate of feldspar in Brent Group reservoirs, North Sea: a regional synthesis of diagenesis in shallow, intermediate, and deep burial environments / Geological Society, London, Special Publications, 61:329-350, doi:10.1144/GSL.SP.1992.061.01.17 --- Nicholas B. Harris: Burial diagenesis of Brent sandstones: a study of Statfjord, Hutton and Lyell fields / Geological Society, London, Special Publications, 61:351-375, doi:10.1144/GSL.SP.1992.061.01.18 --- P. J. Hamilton, M. R. Giles, and P. Ainsworth: K-Ar dating of illites in Brent Group reservoirs: a regional perspective / Geological Society, London, Special Publications, 61:377-400, doi:10.1144/GSL.SP.1992.061.01.19 --- R. Stuart Haszeldine, J. F. Brint, A. E. Fallick, P. J. Hamilton, and S. Brown: Open and restricted hydrologies in Brent Group diagenesis: North Sea / Geological Society, London, Special Publications, 61:401-419, doi:10.1144/GSL.SP.1992.061.01.20 --- A. J. C. Hogg, E. Sellier, and A. J. Jourdan: Cathodoluminescence of quartz cements in Brent Group sandstones, Alwyn South, UK North Sea / Geological Society, London, Special Publications, 61:421-440, doi:10.1144/GSL.SP.1992.061.01.21 --- Stephen Larter and Idar Horstad: Migration of petroleum into Brent Group reservoirs: some observations from the Gullfaks field, Tampen Spur area North Sea / Geological Society, London, Special Publications, 61:441-452, doi:10.1144/GSL.SP.1992.061.01.22 --- J. D. Kantorowicz, M. R. P. Eigner, S. E. Livera, F. S. Van Schijndel-Goester, and P. J. Hamilton: Integration of petroleum engineering studies of producing Brent Group fields to predict reservoir properties in the Pelican Field, UK North Sea / Geological Society, London, Special Publications, 61:453-469, doi:10.1144/GSL.SP.1992.061.01.23 --- Brian Moss: The petrophysical characteristics of the Brent sandstones / Geological Society, London, Special Publications, 61:471-496, doi:10.1144/GSL.SP.1992.061.01.24 --- Erratum --- Erratum: Brent Group: sequence stratigraphy and regional implications / Geological Society, London, Special Publications, 61:ERR, doi:10.1144/GSL.SP.1992.061.01.26

Description / Table of Contents: A three-dimensional theory is derived to describe the temporal behavior of gravity currents of cohesionless granular media, in an attempt to model the motion of dense, flow-type snow avalanches, ice and rock slides. A mohr-Coulomb yield criterion is assumed to describe the constitutive behavior of the material, and the basal bed friction is described similarly by a Coulomb type of friction. A drag term is included in order to model the occurrence of flow regimes where boundary drag becomes non-negligible. Data from laboratory simulations are compared to a series of numerical studies based on the aforementioned theory. A nondimensional, depth and width averaged form of the theory is considered. A Lagrangian finite difference scheme is then applied to numerically model some limiting cases of the governing equations. Two different numerical models are developed, tested and compared to experimental values. The results indicate that the model can account for flow transitions by inclusion of the drag term when the initial inclination angle is large enough to affect boundary drag. Furthermore, the temporal and spatial evolution of the granulate and final runout position can be predicted to values well within the experimental error.