bluuebunny/crossref_metadata_2025_split huggingface dataset:
Error analysis for the determination of tectonic rotation from paleomagnetic data
Authors: Demarest Harold H. 
Published: February 2008

Appendix B is available with entire article on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document B83‐001; $2.50. Payment must accompany order.Recent determinations of tectonic rotation and flattening from paleomagnetic data have exaggerated the size of the confidence limits or error bars by about 25%. This has been caused by the misuse of conventional error propagation formulas to derive one degree of freedom error bars from a two dimensional cone of confidence (α95). An analytical calculation, which is valid when error bars are small, shows that the correct error bars are 75% to 80% of the values derived in previous studies. I have used numerical integration to check on the applicability of the analytical solution and to calculate error bars when the analytical approximation cannot be used. The analytical approximation may be used whenever α95 is less than 10° and the mean inclination is not too close to vertical. Confidence limits given for tectonic rotation and flattening in recent literature are too large and should be reduced by 20–25%. Narrowing the error bars in this way permits a more accurate interpretation of paleomagnetic data.
Crustal and upper mantle structure of the northern and central Sierra Nevada
Authors: Mavko Barbara B. , Thompson George A. 
Published: February 2008

Supplement available with entire article on microfiche. Order from the American Geophysical Union, 2000 Florida Avenue, N. W., Washington, D.C., 2009. Document B83‐002; $2.50. Payment must accompany order.Teleseismic data were recorded within the Sierra Nevada to look for lateral variations in the upper mantle. The data were collected at both temporary and permanent stations, and P wave residuals were computed. After correcting the P residual data for crustal and topographic effects, there is still a variation of as much as 0.5‐0.6 s from the north end of the Sierra Nevada to Mono Lake, located east of the central part of the range. In addition, there are significant variations in travel time patterns, depending on the azimuth of wave arrivals. Two simple modeling approaches have been used to infer the upper mantle velocity structure from the observed variations in travel time. In the first, it is assumed that the velocity variations are distributed throughout a depth range of about 60–160 km. One model that fits the data indicates a north‐to‐south trend in upper mantle P velocities from about 7.9 km/s at the north end of the Sierra to 7.6 km/s near Mono Lake. Superimposed is a west‐to‐east trend from 7.85 km/s under the Sierra Nevada crest to 7.7 km/s east of Lake Tahoe. In the second modeling approach, a fixed velocity contrast is assumed between the lithosphere and asthenosphere with variations in travel time resulting from variations in lithospheric thickness. One model, consistent with the observations, indicates a thinning of the lithosphere from 110 km at the north end of the Sierra to 60 km near Mono Lake.
Magnetostratigraphy and geochronology of northwest Iceland
Authors: McDougall Ian , Kristjansson Leo , Saemundsson Kristjan 
Published: February 2008

The NW peninsula of Iceland is built mainly by tholeiitic, low K flood basalts that show a regional southeasterly dip, generally of less than 10°. From the lavas mapped and drilled for paleomagnetic measurements (a total of 1261 flows), two continuous composite sections were constructed, one on the western side of the peninsula 4055 m thick comprising 456 lavas and the other adjacent to the east coast, 3165 m thick comprising 396 lavas. K‐Ar age measurements were made on more than 70 lavas distributed throughout the two sections. These two lava sequences are about 90 km apart along strike, and although direct stratigraphic correlation is not possible between them, the evidence indicates that the eastern section is stratigraphically younger than that in the west, with some overlap. The results show that the lava sequences were erupted over an interval extending from about 14 to 8 Ma ago in the middle to late Miocene. Remarkably linear relations are found between the measured age and cumulative stratigraphic thickness for both sections, indicating rather uniform local rates of growth of the lava piles. For the western composite section a growth rate of 1820 m/Ma is found, contrasting with a much lower growth rate of 670 m/Ma for the eastern sequence. The average thickness of individual lavas in both sections is close to 8 m. The average time between eruptions of lavas in the western section is 5000 years, compared with a value of 12,000 years for the eastern section. The regional geology together with our measurements are interpreted in terms of crustal accretion processes by which the NW peninsula of Iceland was constructed by eruption of lavas from a spreading center of northeasterly strike. It is not clear whether the differences in rates of growth of the lava pile in the western and eastern sections are because of variation in eruptive activity with time or because eruptive activity has varied along the strike of the spreading center. Paleomagnetic measurements on the lavas provide a detailed history of polarity of the geomagnetic field during the interval 14–8 Ma ago. For the eastern composite section there is excellent and unambiguous correlation of the observed polarity pattern with the marine magnetic anomaly record. From these data we obtain an age of 9.6 Ma for the younger boundary of marine magnetic anomaly 5Table 1 is available with, entire article on microfiche. Order from American Geophysical Union, 2000 Florida Ave., N.W., Washington, D.C. 20009.
The role of water in the deformation of dunite
Authors: Chopra P. N. , Paterson M. S. 
Published: February 2008

Specimens of two natural dunites (Anita Bay, of 100 μm grain size, and Åheirn, of 900 μm grain size) have been deformed in experiments at temperatures between 1200° and 1400°C and constant strain rates between 10−4 and 10−6 s−1 in a gas‐medium deformation apparatus at 300 MPa confining pressure. Prior to these experiments the specimens were given a heat treatment in a controlled oxygen fugacity furnace at 1200°C for >60 hours to dehydrate the trace layer silicate minerals present and drive off adsorbed water. The predried specimens are much stronger than specimens tested under wet conditions in an earlier study. The predried specimens also do not show the apparent grain size dependence seen under wet conditions. Infrared absorption measurements on the present specimens and those of the earlier study indicate that for a given rock, flow stress can be correlated with the intensity of a residual “water related” broad absorption. The addition of water to a predried specimen results in both a mechanical reweakening and an intensifying of the broadband infrared component. The weakening of the dunites under wet conditions is probably strongly influenced by the presence of small amounts of a water‐related species in the grain boundaries, but intragranular weakening may also be contributing. It is suggested that the concentration of the water‐related species in the grain boundaries is governed by its concentration in the small melt fraction present. The amounts of water that have been found to be of importance for the strength of these dunites are of the order of 0.01 wt %, amounts much less than most estimates of the water content of the earth's undepleted upper mantle. Such water may have an important role in determining upper mantle flow behavior.Stress‐strain curves for all experiments are available with entire manuscript on microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, DC 20009‐ Document B84‐008, $2.50. Payment must accompany order.
The volcanoseismic swarms of 1981–1983 in the Tahiti‐Mehetia Area, French Polynesia
Authors: Talandier Jacques , Okal Emile A. 
Published: February 2008

During the years 1981–1983, three intense seismic swarms took place in the Tahiti‐Mehetia area of French Polynesia at the presumed location of the Society Island hot spot. The 1981 swarm featured 4000 earthquakes, with a maximum magnitude ML = 4.3, in the immediate vicinity of the island of Mehetia; the 1982 swarm occurred along the flank of the major Teahitia seamount, and involved more than 9000 events; a second swarm occurred at Teahitia in 1983 and involved 3000 events. Although no precise constraint can be placed on the depth of individual events from their travel times to Polynesian stations, features in the evolution of the Mehetia swarm are generally consistent with the probable ascent of a magma body toward the surface. In the case of Teahitia, the recording of abundant tremors of both high and low frequency, particularly intense during the 1983 swarm, is directly similar to cases of documented volcanic eruptions. The swarms are interpreted as episodes of active volcanism, part of the process of building the next island in the chain.Appendix tables are available with the entire article on micro‐fiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document B84‐005; $2.50. Payment must accompany order.
Introduction to Special Section on the Northern Chugach Mountains‐Southern Copper River Basin Segment of the Alaskan Transect, Part 1
Authors: Page Robert A. 
Published: February 2008

This special section of the Journal of Geophysical Research is the first of a two‐part collection of papers addressing the nature and evolution of the lithosphere in southern Alaska. Collectively, these papers document the important role of subduction‐related accretion in continental growth, a process which continues today in southern Alaska.The studies reported in the collection were undertaken as part of the Trans‐Alaska Lithosphere Investigation (TALI), a geological and geophysical transect of the Alaskan lithosphere along a north‐south corridor. The transect follows the route of the trans‐Alaska oil pipeline and extends offshore across the Pacific and Arctic continental margins (Figure 1). Unique among transect studies of the North American lithosphere, TALI features coordinated geological and geophysical investigations along a common corridor crossing the entire continent, from the active convergent Pacific margin to the rifted Arctic margin of Mesozoic age.
The Transient Tracers in the Ocean (TTO) program: The North Atlantic Study, 1981; The Tropical Atlantic Study, 1983
Authors: Brewer Peter G. , Sarmiento Jorge L. , Smethie William M. 
Published: February 2008

The scientific papers here collected result from the Transient Tracers in the Ocean (TTO) program. The two parts of this major geochemical and physical oceanographie expedition took place in the North Atlantic Ocean in 1981 and in the Tropical Atlantic in 1983 on the research vessel Knorr of the Woods Hole Oceanographie Institution.The expeditions, sponsored by the National Science Foundation and the U.S. Department of Energy (North Atlantic only), were designed to observe the passage of man‐made geochemical tracers into the interior of the ocean. The foundations for such an experiment were laid in the 1972‐1978 GEOSECS program. Here, for the first time, a systematic survey revealed the penetration into the thermocline and deep ocean of the products of man's military/industrial activities, principally tritium and carbon‐14 resulting from atmospheric testing of nuclear weapons, which terminated with the nuclear test ban treaty in 1962.
The analysis and interpretation of stratification cycles
Authors: Schwarzacher W. 
Published: February 2008

Beds in carbonate successions often form regular patterns. Either there is a cyclic repetition of beds with different thicknesses, or bundles of beds occur separated from each other by some distinct layer. Any such group will be called a stratification cycle. Cycles of this type are from 0.5 m to several meters in thickness, and they seem to be present throughout the geological column. The analysis of sedimentary cycles involves three stages.(1) Regional mapping is necessary to understand the facies of the sediment. Establishing the lateral persistence of bedding eliminates the possibility that bedding is caused by diagenetic processes.(2) Petrographic examination and, in particular, analyses of primary structures are used to reconstruct the sedimentation conditions during cycle formation. Such conditions are extremely important for judging the time content of individual beds.(3) The quantitative analysis of vertical sections using power spectral methods can find superimposed cycles and enables one to judge their degree of regularity. The latter approach is illustrated using lower Carboniferous limestone sections from NW Ireland as an example. Spectral analysis finds a stratification cycle of 1 to 3 m in thickness. Each cycle consists of between five to seven limestone beds. Upper Jurassic limestone marl successions from southern Germany and late Cretaceous and early Tertiary successions from Italy show a very similar cyclic pattern. The scale of the cycles and their regularity suggest that they are ultimately caused by variations in the earth's orbit, possibly by climatic cycles as was postulated by Milankovitch. However, the exact mechanism which links sedimentation with orbital variations is not known.
Marine gravimetry
Authors: Dehlinger Peter 
Published: February 2008

This report summarizes marine gravity activities undertaken by universities, research institutions, government laboratories, and meter manufacturers but does not include proprietary work such as that undertaken by the petroleum industry. All nonproprietary gravity data are eventually place on file at either the National Geophysical and Solar‐Terrestrial Data Center (NGSDC) of the National Oceanic and Atmospheric Administration (Washington, D.C.) or the Defense Mapping Agency Aerospace Center (DMAAC) Gravity Library (St. Louis) or both.Sea gravity measurements made by U.S. organizations and obtained since the time of the previous International Union of Geodesy and Geophysics report [Dehlinger, 1971] are generally more accurate than those obtained in prior years. The improved measurements result from the combined effects of refinements made on the design and operation of the sea gravity meters and the use of a satellite navigation system to determine ship positions. The satellite systems now in common use make it possible to calculate Eötvös corrections well within 1 mGal [e.g., Chiburis and Dehlinger, 1974b]. The gravity meters are capable of accuracies of 1 mGal in all but severe seas.
Main field and secular variation
Authors: Cain Joseph C. 
Published: February 2008

Research on the main geomagnetic feld and its secular variation advanced slowly over the period 1975–1978, owing mainly to a significant drop in national support. While some achievements can be reported, we must also acknowledge the impact of this decline on the progress in new scientific results and its effect in degrading the quality of the main field models used in other geophysical disciplines.The World Magnetic Survey (WMS) (Zmuda, 1971) and work reported in the last Quadrennial Review (Cain, 1975) gave us some new insights into the main field not previously available. We obtained a rough outline of that part of the field describable by spherical harmonic wave numbers from n‐8 to about 20 and for the first time had a picture of the global anomaly structure covering the range from about 2000 Km (n = 20 = 40,000/2000) down to perhaps 400 km. However, the WMS momentum was largely lost during the last quadrennium, and these new features were not investigated in detail. As will be seen subsequently, plans for the next few years may brighten the picture considerably.
On solar cosmic rays
Authors: Van Hollebeke M. A. I. 
Published: February 2008

This report summarizes those major results obtained over the last four years, which have contributed to a better understanding of flare accelerated particle phenomena. A detailed review covering the extensive literature on solar cosmic rays in recent years is beyond the scope of this report. Instead, the major developments in this area are high‐lighted and an attempt is made to place them in perspective with some fundamental questions in astrophysics.The primary goal in studying solar cosmic rays is to understand the processes of particle acceleration in the solar flare and the physics of particle propagation in the solar corona including the storage and release of the accelerated particles. Related to the problem of energetic solar particles is a wide variety of different solar phenomena such as a number of different type of radio emission, X‐ray emission from bremsStrahlung of energetic electrons, γ ray line and continuum emission.
Experimental igneous petrology
Authors: Eggler David H. 
Published: February 2008

The 1975–1978 quadrennium was a period in which research in igneous petrology continued in many of the areas of interest of the previous quadrennium (Boettcher, 1975, sect. A)—that is, processes of melting and phase transformations in the Earth and planetary mantles and igneous processes that are peculiar to specific tectonic regimes. The object of these studies is understanding the contribution of igneous events to the evolution of crust‐mantle systems.The references in the bibliography cover the period from the latter months of 1974 to the end of 1978. References listed are believed to reflect both the contributions of geoscientists of the United States and the interactions between U.S. scientists and their colleagues in foreign countries, in particular other countries of the Western world.
Geothermal systems and their energy resources
Authors: White Donald E. , Guffanti Marianne 
Published: February 2008

Geothermal systems have not been reviewed comprehensively in previous IUGG Quadrennial Reports, although thermal aspects of the shallow crust were considered by Diment (1975). Nearly all types of geothermal systems are reviewed in this report, with emphasis on U. S. systems that are most likely to be utilized as energy sources. Active volcanism and the generation and evolution of magma are not considered in detail.Outstanding advances in geothermal resource utilization include: (1) Rapid growth in electrical generation from hydrothermal convection systems. All installed capacity in the U. S. to date (610 MWe in February, 1979) is from the huge vapor‐dominated system at The Geysers, California. Rapid expansion of capacity to ∼1200 MWe is expected by 1982; this includes at least 200 MW from several hot‐water systems, now that the most serious technological, environmental, and Federal leasing problems seem to have been solved; (2) Increasing interest in low‐temperature geothermal waters for non‐electrical (direct) uses; (3) Recognition of the resource potential of the geopressured environment of the Gulf Coast for geothermal and methane energy.
Meteorite research
Authors: Wood John A. , Motylewski Karen 
Published: February 2008

Meteorites contain a record of events and processes in the three earliest stages of solar system history: (1) formation of the raw material that was to become the solar system; (2) processing of the condensable component of this material in a nebular disk that circled the protosun; and (3) processing of condensed material after it had accumulated into planetesimals of asteroidal dimension. To test our acumen, the record has been written in cryptic rather than plain language. Progress toward breaking the cipher, made in the U.S. during the period 1975–1978, is summarized below.Much of the record in meteorites is contained in patterns of isotope abundances. This particular field of research is admirably reviewed by Podosek [1978].
Solar wind plasma processes and transport
Authors: Feldman William C. 
Published: February 2008

The solar wind is one of the few examples of an astrophysical plasma accessible to in situ measurement. This accessibility allows a determination of the distribution of internal energy in sufficient detail to evaluate and understand the various kinetic mechanisms which cooperate to determine plasma transport. Because the transport properties of a gas affect its dynamical evolution as well as its internal state, studies of solar wind transport are important toward an eventual understanding of 1 ) acceleration mechanisms responsible for the coronal expansion, 2) the interaction between the solar wind and solar system bodies such as the planets, comets, and asteroids, 3) the propagation and evolution of disturbances through interplanetary space and, 4) interplanetary acceleration mechanisms which contribute to, and affect the distribution of, the local energetic particle population.The purpose of this report is to outline what I feel were the most significant advances made in solar wind transport since 1974 and to provide a complete listing of relevant literature for this interval. A guide to previous literature can be traced through the individual research papers as well as through the several comprehensive review articles published during this interval. The references are listed at the end of the present report.
Advancements in remote sensing of the atmosphere
Authors: Lhermitte Roger 
Published: February 2008

The infrared methods developed in the last two decades for the remote sensing of atmospheric parameters by infrared sensors installed aboard orbiting (research and operational) and geostationary (operational) satellites have resulted in numerous meteorological interpretations allowed by the continuous monitoring of cloud and earth surface emission. Also, the inversion methods, in which atmospheric radiances simultaneously observed at several wavelengths in the same general absorption band are used to estimate the vertical profile of temperature or concentration of atmospheric gases, have been further applied to the observation of the vertical profiles of atmospheric temperature and water vapor content.The results have shown that, in a cloud‐free atmosphere, tropospheric temperature measurements done by satellite are acceptable but have a limited ability to show low level temperature inversions. Except for the case of thin cirrus, clouds are always considered as emitting black body radiation so that their infrared emission observed in the 10 microns atmospheric window is easily converted into temperature at their top.
The composition, propagation and acceleration of energetic solar particles: A review of United States research 1979–1982
Authors: McGuire R. E. 
Published: February 2008

We study solar energetic particles in an effort to better understand physical processes which occur at the Sun and in the heliosphere, but improvements in our understanding of the physics of these processes should have broader implications in more general astrophysical problems. Among the questions of greatest interest are: (l) what is the basic elemental and isotopic composition of the solar atmosphere, to what extent is this composition reflected in observed energetic solar particles and how do these abundances relate to or influence our understanding of universal and galactic cosmic ray abundances; (2) by what mechanisms, under what conditions and where does the acceleration of solar energetic particles take place; (3) what are the mechanisms by which energetic particles are transported and/or stored in the vicinity of the Sun; (4) how can we describe the escape from the Sun and subsequent transport of charged solar particles through interplanetary space and how can we relate that description to measurable properties of the medium through which they travel?Each of the above points raises numerous and difficult subsidiary questions. But probably the primary obstacle to direct study of these problems is that the various processes and mechanisms are almost inextricably interwoven observationally (Wibberenz, 1979). All measurements that we make of particles in space (e.g., composition, time evolution of intensities and anisotropies, energy spectra) are influenced both by the nature of the original particle acceleration and by the propagation of these particles from the acceleration site to the observing instruments.