Download or read book Chemical Heterogeneity in the Upper Mantle written by Robert A. Duncan and published by . This book was released on 1972 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Earth s Heterogeneous Mantle written by Amir Khan and published by Springer. This book was released on 2015-04-28 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights and discusses recent developments that have contributed to an improved understanding of observed mantle heterogeneities and their relation to the thermo-chemical state of Earth's mantle, which ultimately holds the key to unlocking the secrets of the evolution of our planet. This series of topical reviews and original contributions address 4 themes. Theme 1 covers topics in geophysics, including global and regional seismic tomography, electrical conductivity and seismic imaging of mantle discontinuities and heterogeneities in the upper mantle, transition zone and lower mantle. Theme 2 addresses geochemical views of the mantle including lithospheric evolution from analysis of mantle xenoliths, composition of the deep Earth and the effect of water on subduction-zone processes. Theme 3 discusses geodynamical perspectives on the global thermo-chemical structure of the deep mantle. Theme 4 covers application of mineral physics data and phase equilibrium computations to infer the regional-scale thermo-chemical structure of the mantle.
Download or read book Natural Periodites written by Jean-Claude Christian Mercier and published by . This book was released on 1982 with total page 1314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Heterogeneity in the Crust and Upper Mantle written by John A. Goff and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most of our knowledge about the physical structure and the chemical composition of the Earth's deep interior is inferred from seismic data. The interpretation of seismic waves generally follows the assumption that the Earth's physical structure is grossly layered and that fluctuations of the physical parameters within individual layers are smooth in structure and small in magnitude. While this view greatly facilitates the analytic and interpretative procedure, it is clearly at odds with evidence from outcrops and boreholes, which indicates that compositional, structural and petrophysical heterogeneity in the Earth prevails over a wide range of scales. This book is the first to unify three different views of crustal and upper mantle heterogeneity. It brings together the geological view, which is derived from the analysis of crustal exposures and deep boreholes; the stochastic view, which attempts to find order and structure in these seemingly chaotic data; and the seismological view, which considers the end product of the complex interaction of seismic energy with the heterogeneous structure at depth. John Goff and Klaus Holliger have compiled chapters that explore and quantify the relationship between geological and petrophysical heterogeneity and its seismic response, and use seismic data to probe the fabric of the Earth's interior. Geologists, geostaticians, and geophysicists alike will benefit from the integrative perspective presented in Heterogeneity in the Crust and Upper Mantle: Nature, Scaling, and Seismic Properties, making this text an unparalleled reference for professionals and students in Earth science fields.
Download or read book Geochemical and Fluid Dynamic Investigations Into the Nature of Chemical Heterogeneity in the Earth s Mantle written by Erik Harold Hauri and published by . This book was released on 1992 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt: Variations in the abundances of elements and radiogenic isotopes in mantle derived peridotites and volcanic rocks are chemical integrals over time, space, and process, which ultimately contain information about the role of convection in the earth's mantle in creating, maintaining, and destroying geochemical heterogeneities. Successful inversion of these integrals requires extensive knowledge of the geochemical behavior of elements, the length scales of chemical variability, the evolution with time of geologic systems, the physical properties of mantle rocks, and the driving forces of phenomena which govern heat and mass transport in a dynamic earth. This dissertation attempts to add to this knowledge by examining the trace element and isotope geochemistry of mantle peridotites and oceanic island basalts, and by studying aspects of the flow of viscous fluids driven by thermal buoyancy. The trace element and isotopic systematics of peridotites and associated mafic layers from the Ronda Ultramafic Complex, southern Spain (Chapter 2), provides information bearing on the geochemical behavior of the highly incompatible elements U, Th, and Pb in the mantle, and on the length scales of geochemical variability in a well exposed peridotite massif. Garnet is demonstrated to be a significant host for U in the mantle, and together with clinopyroxene, these two minerals control the abundances and partitioning relationships of U and Th during the melting of anhydrous peridotite. Clinopyroxene, plagioclase, and to a lesser extent garnet are hosts for Pb in mantle peridotite; however, the role of trace sulfide may exert some control over the abundance and partitioning of Pb in some samples. Due to the possibility that Pb is partitioned into sulfide, the U/Pb, Th/Pb, and Ce/Pb ratios measured in clinopyroxene are likely to be higher than the bulk rock. U-Pb age systematics of garnet-clinopyroxene pairs from Ronda peridotites and mafic layers indicate Pb isotopic equilibrium in these samples up to 20-50 Ma ago. The Pb-Pb systematics of garnet- and spinel-facies peridotites and mafic layers indicate a heterogeneity on the order of 3 Ga old. This Pb isotope signature may have been created within the massif 3 Ga ago, or may have been metasomatically imprinted on the massif 1.3 Ga ago by basaltic melts with island arc affinities. The isotopic evolution of Ronda is consistent with at 1.3 Ga ago, and was subsequently incorporated into the subcontinental lithosphere. The very low U, Th, and Pb concentrations in depleted peridotite indicate that recycled crustal materials, with U-Th-Pb concentrations 102-104 times higher than peridotite, will have a larger influence on the isotopic composition of Pb in the mantle than on the Sr and Nd isotopic composition. An investigation of the trace element and isotopic compositions of clinopyroxenes in peridotite xenoliths from Savaii, Western Samoa and Tubuai, Austral Islands (Chapter 3) reveals geochemical signatures which are not present in basalts from these islands, due to the inherent averaging of melting processes. The data indicate similarities in the melting and melt segregation processes beneath these isotopically extreme islands. Samples with LREE depleted clinopyroxenes, with positive Zr and negative Ti anomalies, are the result of poly baric fractional melting of peridotite in the garnet- and spinel lherzolite stability fields, with the Savaii samples having experienced a larger mean degree of melting than the Tubuai samples. The extreme fractionation of HREE in the Savaii samples requires that they have melted to the clinopyroxene-out point (about 20%) while retaining residual garnet; the low concentrations ofHREE in these same samples requires a further 10-20% melting in the spinel lherzolite stability field. The extremely high total degrees of melting experienced by the Savaii samples (33-42%), as well as the high degree of melting in the garnet lherzolite stability field, suggests a mantle plume origin for these xenoliths. A large majority of the xenolith clinopyroxenes from both Savaii and Tubuai are LREE enriched to varying degrees, and many samples display significant intergrain trace element heterogeneity. This highly variable yet systematic heterogeneity was the result of metasomatism by percolating melts undergoing chromatographic trace element fractionation. The trace element compositions of some LREE enriched clinopyroxenes are consistent with the percolating melt being typical oceanic island basalt. The clinopyroxenes with the highest LREE concentrations from both islands, which also have very low Ti and Zr concentrations and large amounts of grain-boundary hosted Ba, require that the percolating melt in these cases had the trace element signature of carbonatite melt. The isotopic composition of one of these "carbonatitic" samples from Tubuai is similar to basalts from this island. The isotopic composition of clinopyroxene in a "carbonatitic" sample from Savaii records 87Sr/86Sr and l43Nd/l44Nd values of .71284 and .512516 respectively, far in excess of the most extreme Samoa basalt values (87Sr/86Sr=.70742, 143Nd/l44Nd=.51264). These "carbonatitic" signatures indicate the presence of volatilerich, isotopically extreme components in the mantle beneath Tubuai and Savaii, which likely have their origins in recycled crustal materials. The Re-Os isotope systematics of oceanic island basalts from Rarotonga, Savaii, Tahaa, Rurutu, Tubuai, and Mangaia are examined (Chapter 4). Os concentration variations suggest that olivine, or a low Re/Os phase associated with olivine, controls the Os concentration in basaltic magmas. The Savaii and Tahaa samples, with high 87Sr/86Sr and 207Pb/204Pb ratios (EMII), as well as basalts from Rarotonga, have 1870s/1860s ratios of 1.026-1.086, within the range of estimates of bulk silicate earth and depleted upper mantle. The basalts from Rurutu, Tubuai, and Mangaia (Macdonald hotspot), characterized by high Pb isotope ratios (HIMU), have 1870sfl860s ratios of 1.117-1.248, higher than any estimates for bulk silicate earth, and higher than Os isotope ratios of metasomatized peridotites. The high 1870s/1860s ratios indicate the presence of recycled oceanic crust in the mantle sources of Rurutu, Tubuai, and Mangaia. Inversion of the isotopic data for Mangaia (endmember HIMU) indicate that the recycled crustal component has Rb/Sr, Sm/Nd, Lu/Hf, and Th/U ratios which are very similar to fresh MORB glasses, and U/Pb and Th/Pb ratios which are within the range of MORB values, but slightly higher than average N-MORB. These results indicate that the low-temperature alteration signature of altered oceanic crust may be largely removed during subduction, and that oceanic crust was recycled into to the lower mantle source of the Macdonald hotspot plume. Furthennore, the high 187Os/l86Os ratios of the Tubuai and Mangaia basalts indicates that percolation through depleted mantle peridotite (187Os/186Qs=1.00-1.08), observed to occur in the Tubuai xenoliths, had little influence on the composition of the erupted basalts. A fluid dynamic model for mantle plumes is developed (Chapter 5) by examining a vertical, axisymmetric boundary layer originating from a point source of heat, and incorporating experimentally constrained rheological and physical properties of the mantle. Comparison of linear (n=l) and non-Newtonian (olivine, n=3) rheologies reveals that non-Newtonian plumes have narrower radii and higher vertical velocities than corresponding Newtonian plumes. The non-Newtonian plumes also exhibit "plug flow" at the conduit axis, providing a mechanism for the transport of deep mantle material, through the full depth of the mantle, in an unmixed state. Plumes are demonstrated to entrain ambient mantle via the horizontal conduction of heat, which increases the buoyancy and lowers the viscosity of mantle at the plume boundary. Streamlines calculated from the fluid dynamic model demonstrate that most of the entrained mantle originates from below 1500 km depth. Parameterization of the entrainment mechanism indicates that the factional amount of entrained mantle is lower in stronger, hotter plumes due to their higher vertical velocities. Examination of the global isotopic database for oceanic island basalts reveals the presence of a mantle component (FOZO), common to many hotspots worldwide, characterized by depleted 87Sr/86Sr and 143Nd/l44Nd, radiogenic 206,207,208Pb/204Pb, and high 3He/4He. This component is isotopically distinct from the source of MORB; thus, with the exception of ridge centered hotspots such as Iceland and the Galapagos, upper mantle does not appear to be a component in most hotspots, in agreement with entrainment theory. The combined fluid dynamic and isotopic results indicate that both FOZO and the enriched mantle components (EMI, EMil, and HIMU) are located in the lower mantle. Furthermore, high 3He/4He in FOZO precludes an origin for FOZO-bearing plumes in a thermal boundary layer at 670 km depth in the mantle. Since a 670 km thermal boundary layer would be replenished by the downward motion of the upper mantle, an origin for FOZO at 670 km would require either 1) a high 3He/4He signature in the MORB source, or 2) entrainment of MORB mantle into intraplate plumes, neither of which is observed in the OIB isotope data. This indicates that the 670 km discontinuity is not a barrier to mantle convection. The preservation of isotopically different upper and lower mantles does not require layered convection, but is probably the result of an increasing residence time with depth in the mantle, possibly caused by an increase in the mean viscosity of the mantle with depth
Download or read book New Theory of the Earth written by Don L. Anderson and published by Cambridge University Press. This book was released on 2007-04-12 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory of the Earth is an interdisciplinary advanced textbook on the origin, composition, and evolution of the Earth's interior: geophysics, geochemistry, dynamics, convection, mineralogy, volcanism, energetics and thermal history. This is the only book on the whole landscape of deep Earth processes which ties together all the strands of the subdisciplines. It is a complete update of Anderson's Theory of the Earth (1989). It includes many new sections and dozens of new figures and tables. As with the original book, this new edition will prove to be a stimulating textbook on advanced courses in geophysics, geochemistry, and planetary science, and supplementary textbook on a wide range of other advanced Earth science courses. It will also be an essential reference and resource for all researchers in the solid Earth sciences.
Download or read book The Heterogeneity and Volatile Content of Earth s Mantle Magmas and Crust written by Benjamin Macy Urann and published by . This book was released on 2021 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores the volatile content of the mantle, subducted oceanic crust, and arc magmas as well as the structure of slow spreading ocean crust and the heterogeneity of Earth’s upper mantle. In Chapter 2, I directly explore the halogen (F and Cl) content of mantle minerals in situ, then use these measurements to assess the halogen content of the upper mantle. In Chapter 3, I investigate the volatile content of Raspas eclogites (SW Ecuador), a proxy for deeply subducted oceanic crust, to evaluate volatile transfer from crustal generation at divergent plate boundaries (e.g., mid-ocean ridges) to recycling of ocean crust at subduction zones. In Chapter 4, I use the H2O content of nominally anhydrous minerals in plutonic arc cumulates to elucidate the H2O content of the melts from which the rocks crystallized. In this way, I assert that primitive arc magmas may contain 4–10 wt.% H2O and through fractional crystallization up to ~20 wt.% H2O, making them far more hydrous than traditional methods (i.e., olivine-hosted melt inclusions) surmise. In Chapter 5, I show that mantle peridotite exposed along the 16°N region of the Mid-Atlantic Ridge originated in an arc setting and has been remixed into subridge mantle, indicating that the sub-ridge mantle is more heterogeneous and depleted than inferences made from mid-ocean ridge basalts suggest. Chapter 6 surveys the life cycle of oceanic core complexes through zircon geochronology and posits an updated framework for understanding the termination of oceanic core complexes, and more broadly oceanic detachment faults. Together, this contribution highlights the chemical heterogeneity of the mantle, and quantifies the full extent of volatiles hosted by mantle and crustal reservoirs.
Download or read book The Evidence for Chemical Heterogeneity in the Earth s Mantle written by Mineralogical Society (Great Britain). Geochemistry Group and published by . This book was released on 1980 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mantle Convection and Surface Expressions written by Hauke Marquardt and published by John Wiley & Sons. This book was released on 2021-07-07 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multidisciplinary perspective on the dynamic processes occurring in Earth's mantle The convective motion of material in Earth's mantle, powered by heat from the deep interior of our planet, drives plate tectonics at the surface, generating earthquakes and volcanic activity. It shapes our familiar surface landscapes, and also stabilizes the oceans and atmosphere on geologic timescales. Mantle Convection and Surface Expressions brings together perspectives from observational geophysics, numerical modelling, geochemistry, and mineral physics to build a holistic picture of the deep Earth. It explores the dynamic processes occurring in the mantle as well as the associated heat and material cycles. Volume highlights include: Perspectives from different scientific disciplines with an emphasis on exploring synergies Current state of the mantle, its physical properties, compositional structure, and dynamic evolution Transport of heat and material through the mantle as constrained by geophysical observations, geochemical data and geodynamic model predictions Surface expressions of mantle dynamics and its control on planetary evolution and habitability The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Download or read book Upper Mantle Heterogeneities from Active and Passive Seismology written by K. Fuchs and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: 600 km giving insight into the 3D structure of the upper mantle. These data are confronted with the requirements of the CTBT for 3D regional seismic models of the lithosphere-asthenosphere system. The two primary purposes of the present work are, first, to present these seismic observations on super long-range profiles in digitised format, using peaceful nuclear explosions (PNE) in the former USSR, and, second, to present the joint thoughts of experts from the deep seismic sounding (DSS) and the comprehensive test ban treaty (CTBT) communities. Implications for petrological and other earth science disciplines are presented. Audience: The CTBT community and earth scientists interested in the 3D structure of the lithosphere-asthenosphere system.
Download or read book Natural Peridotites written by Jean-Claude Christian Mercier and published by . This book was released on 1977 with total page 1336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of the Earth written by Don L. Anderson and published by Wiley-Blackwell. This book was released on 1989 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theory of the Earth is a combination reference and textbook that every exploration geologist and research scientist should have on his/her bookshelf. It is also suitable for advanced undergraduate, as well as graduate level geophysics courses. The emphasis is on the origin, evolution, structure and composition of the earth′s interior. It treats the pertinent aspects of solid state physics, thermodynamics, geochemistry, petrology, and seismology in sufficient detail for all who seek current information on geochemistry, solid state physics, and physics of the earth or planets
Download or read book The Lithosphere written by Irina Artemieva and published by Cambridge University Press. This book was released on 2011-07-28 with total page 795 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presenting a coherent synthesis of lithosphere studies, this book covers a range of geophysical methods (seismic reflection, refraction, and receiver function methods; elastic and anelastic seismic tomography; electromagnetic and magnetotelluric methods; thermal, gravity and rheological models), complemented by petrologic and laboratory data on rock properties. It also provides a critical discussion of the uncertainties, assumptions, and resolution issues that are inherent in the different methods and models of the lithosphere. Multidisciplinary in scope, global in geographical extent, and covering a wide variety of tectonics settings across 3.5 billion years of Earth history, this book presents a comprehensive overview of lithospheric structure and evolution. It is a core reference for researchers and advanced students in geophysics, geodynamics, tectonics, petrology, and geochemistry, and for petroleum and mining industry professionals.
Download or read book Deep Carbon written by Beth N. Orcutt and published by Cambridge University Press. This book was released on 2019-10-17 with total page 687 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive guide to carbon inside Earth - its quantities, movements, forms, origins, changes over time and impact on planetary processes. This title is also available as Open Access on Cambridge Core.
Download or read book Ultrahigh pressure Mineralogy written by Russell Julian Hemley and published by de Gruyter. This book was released on 1998 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 37 of Reviews in Mineralogy moves from the complexity of rocks to their mineral components and finally to fundamental properties arising directly from the play of electrons and nuclei. This volume was prepared for a short course by the same t
Download or read book Large Scale Heterogeneity of the Upper Mantle Inferred from Measurements of Free Oscillations written by James Peter Davis and published by . This book was released on 1986 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geophysical Abstracts written by and published by . This book was released on 1970 with total page 710 pages. Available in PDF, EPUB and Kindle. Book excerpt:
