Download or read book A Cross ridge Seismic Refraction Survey of the East Pacific Rise at 10 South written by Ervin Wesley Scarlett and published by . This book was released on 1979 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bibliography and Index of Geology written by and published by . This book was released on 1992 with total page 1404 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magmatic Systems written by Michael P. Ryan and published by Academic Press. This book was released on 1994-08-26 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: With its integrated and cohesive coverage of the current research, Magmatic Systems skillfully explores the physical processes, mechanics, and dynamics of volcanism. The text utilizes a synthesized perspective--theoretical, experimental, and observational--to address the powerful regulatory mechanisms controlling the movement of melts and cooling, with emphasis on mantle plumes, mid-ocean ridges, and intraplate magmatism. Further coverage of subduction zone magmatism includes:Fluid mechanics of mixed magma migrationInternal structure of active systemsGrain-scale melt flowRheology of partial meltsNumerical simulation of porous media melt migrationNonlinear (chaotic and fractal) processes in magma transportIn all, Magmatic Systems will prove invaluable reading to those in search of an interdisciplinary perspective on this active topic. Key Features* Fluid mechanics of magma migration from surface region to eruption site* Internal structure of active magmatic systems* Grain-scale melt flow in mantle plumes and beneath mid-ocean ridges* Physics of magmatic systems and magma dynamics

Download or read book A Baseline for Upper Crustal Velocity Variations Along the East Pacific Rise written by Mary Elizabeth Kappus and published by . This book was released on 1991 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fine Scale Seismic Structure of Upper Crust on the East Pacific Rise written by Chin Chen and published by . This book was released on 1985 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Seismic Attenuation Structure of the East Pacific Rise written by William Sam Douglas Wilcock and published by . This book was released on 1992 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of seismic propagation through oceanic crust have contributed enormously to our understanding of the generation and evolution of oceanic crust However, such work has largely been confined to the seismic velocity structure. In this thesis we present results from a study of seismic attenuation using a data set collected for three-dimensional tomographic imaging of a fast-spreading ridge. The experiment location at 9°30'N on the East Pacific Rise is the site of a strong mid-crustal seismic reflector which has been inferred to be the roof of a small axial magma chamber at about 1.6 km depth. A spectral method is used to estimate t*, a measure of the integrated attenuation along a wave path. Such a method asswnes that the dominant frequency-dependent component of propagation is intrinsic attenuation. A logarithmic parameterization is then used to invert t* measurements for Q-1 structure asswning that the velocity structure is given from earlier studies. To evaluate the method of Q tomography a full-waveform finitedifference technique which does not include attenuation is used to calculate solutions for seismic propagation through a two-dimensional velocity model. The results show a complex pattern of seismic propagation in the vicinity of the axial magma chamber. The first arrival always passes above the magma chamber. However, for paths of significant length that cross the rise axis the amplitude of this arrival is very small, and the first phase with significant amplitude is a diffraction below the magma chamber. High-amplitude Moho turning and PP arrivals may also be important secondary arrivals. Synthetic inversions show the importance of selecting time windows for power spectral estimation which are dominated by a single phase and of using wave paths which closely corresponds to that of the selected phase. A comparison of the finite difference solutions and the predictions of the a twodimensional, exact ray-tracing algorithm with record sections obtained during the tomography experiment significantly improves our understanding of seismic propagation across the East Pacific Rise. The results enable an objective choice of the position and length of the time window fort* estimation. Moreover, additional constraints are incorporated into an approximate three-dimensional ray-tracing algorithm used in the inversion so that the wave paths more closely correspond to those of the desired phase. The full data set to be inverted comprises about 3500 t* estimates and includes crustal paths which do not cross the rise axis, diffractions above and below the axial magma chamber, and Moho-turning phases. Wave paths for the Moho-turning phases cross the rise axis at a wide range of lower crustal depths. The Q-1 models resulting from two-dimensional and three-dimensional tomographic inversions show that the attenuation of seismic waves on the East Pacific Rise is dominated by two regions of low Q; one in the upper 1 km of crust, and one at depths greater than about 2 km below the rise axis. While the data do not resolve the details of vertical variations in near-surface Q-1, the results show a substantial variation in shallow attenuation within 0.05 My of the rise axis. On-axis, Q values averaged over the upper 1 km are about 100, while off-axis the average value rapidly decreases to about 30. Measurements of the seismic velocity suggest that the thickness of the surficial highporosity extrusive layer increases substantially off-axis. If such thickening is entirely responsible for the observed change in near-surface attenuation then Q within the extrusive layer must be much less than 20. Alternatively, in situ changes in porosity may also contribute to the observed increase in attenuation. Since significant tectonic activity is apparently restricted to locations well off-axis we suggest that such variations in porosity may result from hydrothermal activity. Regions of hydrothermal downwelling located off-axis will be subject to cooling and thermally-induced cracking while upwelling regions on-axis may be accompanied by rapid infilling of existing pores by hydrothermal deposits. Estimates of t* for all phases propagating below the magma chamber are markedly higher than those for other phases, resulting in Q-1 models which include a region of low Q extending from 2 to 7 km depth below the rise axis. The lowest Q values resolved are about 25-30 both immediately below the magma chamber and within the lower crust. While there is some evidence for a small decrease in attenuation with depth in the lower crust, axial Q values at depths ranging from less than 2.5 to 6 km are relatively constant, always lying below 50. Laboratory measurements at seismic frequencies suggest that Q values of 25-50 require only very small fractions of partial melt. The attenuation observations thus place constraints on the dimensions of the axial magma chamber and strongly suggest that the thickness of the region containing more than a few percent of partial melt is no more than 1 km.

Download or read book Seismic Constraints on Shallow Crustal Processes at the East Pacific Rise written by Gail L. Christeson and published by . This book was released on 1994 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is concerned with understanding how oceanic crust is emplaced at mid-ocean ridges. The emphasis is upon fast-spreading ridges, and the use of seismic techniques to image the uppermost several hundred meters of the crust. We present the results of nine on-bottom seismic refraction experiments carried out over young East Pacific Rise (EPR) crust. The experiments are unusual in that both the source and receiver are located within a few meters of the seafloor, allowing high-resolution determinations of shallow crustal structure. Three experiments were located within the axial summit caldera (ASC), over 'zero-age' crust. The seismic structure at these three locations is fundamentally the same, with a thin (60 m) surficial low-velocity (

Download or read book The Crustal Structure of the East Pacific Rise Near 125 0 N written by Mark Steven Burnett and published by . This book was released on 1990 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the Ocean Drilling Program written by Ocean Drilling Program and published by . This book was released on 1993 with total page 1038 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecosystem Dynamics in a Polar Desert written by and published by American Geophysical Union. This book was released on 1998 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents information from the primary abiotic forces defining the system, and from the present hydrology, biogeochemistry and physics of major sites of organic carbon production of the McMurdo Dry Valleys. Additionally, research on the physical, chemical, and biological properties of the dry valley soils is included. The role of environmental management in long-term ecological studies is also addressed. The accompanying CDROM provides details and scale to visualize the McMurdo Dry Valleys from an ecosystem perspective.

Download or read book Three dimensional Crustal Structure of East Pacific Rise Discontinuities from Tomographic Inversions written by Sara Bazin and published by . This book was released on 2000 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exploring the Earth s Crust written by C. Prodehl and published by Geological Society of America. This book was released on 2012 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This volume contains a comprehensive, worldwide history of seismological studies of the Earth's crust using controlled sources from 1850 to 2005. Essentially all major seismic projects on land and the most important oceanic projects are covered. The time period 1850 to 1939 is presented as a general synthesis, and from 1940 onward the history and results are presented in separate chapters for each decade, with the material organized by geographical region. Each chapter highlights the major advances achieved during that decade in terms of data acquisition, processing technology, and interpretation methods. For all major seismic projects, the authors provide specific details on field observations, interpreted crustal cross sections, and key references. They conclude with global and continental-scale maps of all field measurements and interpreted Moho contours. An accompanying DVD contains important out-of-print publications and an extensive collection of controlled-source data, location maps, and crustal cross sections."--Publisher's description.

Download or read book Ophiolite Concept and the Evolution of Geological Thought written by Yildirim Dilek and published by Geological Society of America. This book was released on 2003-01-01 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Solid Earth written by C. M. R. Fowler and published by Cambridge University Press. This book was released on 2004-12-20 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Solid Earth is a general introduction to the study of the physics of the solid Earth, including the workings of both the Earth's surface and its deep interior. The emphasis throughout is on basic physical principles rather than instrumentation or data handling. The second edition of this acclaimed textbook has been revised to bring the content fully up-to-date and to reflect the most recent advances in geophysical research. It is designed for undergraduates on introductory geophysics courses who have a general background in the physical sciences, including introductory calculus. It can also be used as a reference book for graduate students and other researchers in geology and geophysics. Each chapter ends with exercises of various degrees of complexity, for which solutions are available to instructors from www.cambridge.org/9780521893077. The book contains an extensive glossary of geological and physical terms, as well as appendices that develop more advanced mathematical topics.

Download or read book Tectonic Magmatic Hydrothermal and Biological Segmentation of Mid ocean Ridges written by C. J. MacLeod and published by Geological Society of London. This book was released on 1996 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Treatise on Geophysics written by and published by Elsevier. This book was released on 2015-04-17 with total page 5604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Treatise on Geophysics, Second Edition, is a comprehensive and in-depth study of the physics of the Earth beyond what any geophysics text has provided previously. Thoroughly revised and updated, it provides fundamental and state-of-the-art discussion of all aspects of geophysics. A highlight of the second edition is a new volume on Near Surface Geophysics that discusses the role of geophysics in the exploitation and conservation of natural resources and the assessment of degradation of natural systems by pollution. Additional features include new material in the Planets and Moon, Mantle Dynamics, Core Dynamics, Crustal and Lithosphere Dynamics, Evolution of the Earth, and Geodesy volumes. New material is also presented on the uses of Earth gravity measurements. This title is essential for professionals, researchers, professors, and advanced undergraduate and graduate students in the fields of Geophysics and Earth system science. Comprehensive and detailed coverage of all aspects of geophysics Fundamental and state-of-the-art discussions of all research topics Integration of topics into a coherent whole

Download or read book Petroleum Abstracts written by and published by . This book was released on 1991 with total page 1512 pages. Available in PDF, EPUB and Kindle. Book excerpt: