The paleomagnetic history of the volcanic rocks of Easter
Island was investigated using standard paleomagnetic techniques.
The remanent magnetization of 673 specimens from the three volcanic
episodes recognized on the island were measured using a spinner
magnetometer. Inclinations, declinations and virtual geomagnetic
poles were calculated for each flow. The majority...
During Ocean Drilling Program Leg 202, detailed shipboard paleomagnetic measurements at Sites 1233 and 1234 identified a reproducible high-resolution record of paleomagnetic secular variation (PSV) at each site. These records also contained evidence for three magnetic field excursions. This paper summarizes the complete paleomagnetic record from Site 1233 and the...
This dissertation uses argon geochronology and cosmogenic nuclide surface exposure dating methods to address three research questions. The first question concerns a geomagnetic instability recorded in lava flows on the island of Floreana in the Galapagos Archipelago. Changes in the Earth’s magnetic field (intensity and orientation) occur frequently throughout geologic...
In the final phase of their spawning migration, Pacific salmon use chemical cues to identify their home river, but how they navigate from the open ocean to the correct coastal area has remained enigmatic [1]. To test the hypothesis that salmon imprint on the magnetic field that exists where they...
Long-period global-scale electromagnetic induction studies of deep Earth conductivity are based almost exclusively on magnetovariational methods and require accurate models of external source spatial structure. We describe approaches to inverting for both the external sources and three-dimensional (3-D) conductivity variations and apply these methods to long-period (T≥1.2 days) geomagnetic observatory...
Stratigraphy and chronology are essential to sedimentological study of Earth system histories. And, stratigraphy and chronology are often challenging and interesting problems themselves. The Quaternary (2.588 Ma - present) experienced paleoenvironmental and paleo-geomagnetic variability well outside the range of the recent instrumental record, providing the opportunity to place recent observations...
A summary of the first. year's results in a program of current measuring techniques employing the electromagnetic method is presented. The data was taken on hydrographic survey cruises ranging to 165 miles offshore from Oregon. The measurements in this first phase consist solely of those taken by the method of...
We report the behavior of the earth's magnetic field for a transition recorded in lavas at the volcanic island of
Huahine in French Polynesia, south-central Pacific Ocean. Detailed intermediate fields are observed that record an
apparent N-N excursion. The available K-Ar ages indicate that most volcanic rocks of the southern...
Regeneration of the Earth’s magnetic field by convection in the liquid core produces a broad spectrum of time variation. Relative palaeointensity measurements in marine sediments provide a detailed record over the past 2 Myr, but an explicit reconstruction of the underlying dynamics is not feasible. A more practical alternative is...
Magnetotelluric (MT) data from two sites 150 and
300 km southeast of San Francisco, California (geomagnetic
dipole latitude: 43 degrees, L approximately 1.9) show that
the usual MT assumption of spatially uniform external magnetic
fields is violated to a significant degree in the period
range 10-30 s. Inter-station transfer functions...
Investigations of the behavior of the geomagnetic field on geological timescales rely on globally distributed data sets from dated lava flows. We present the first suitable data from the Arctic region, comprising 37 paleomagnetic directions from Jan Mayen (71°N, 0.2–461 ka) and Spitsbergen (79°N, 1–9.2 Ma) and five paleointensity results....
A volcanic sequence almost 700 meters thick has been sampled in the Punaruu valley on the island of
Tahiti, southern central Pacific Ocean. Detailed paleomagnetic results have been obtained from 123 sites. Three
reversals are recorded in this sequence. Age determinations (K-Ar) indicate that the youngest reversal corresponds
to the...
New Paleomagnetic Secular Variation (PSV) data from Fish Lake, Utah, USA, along with previously published regional records, allow us to build an independently dated Western North America PSV stack (WNAM17) from about 35 to 15 ka that quantifies dating and paleomagnetic uncertainties. In February 2014, we recovered a composite 11-m-long...
I derive probability densities for virtual geomagnetic pole( VGP) longitudes for a general statistical model of
local magnetic field variations. I show that even for very
simple statistically homogeneous models of secular variation,
the distribution of VGP longitudes is peaked 90° away
from the sampling longitude. Thus, when sites are...
The development of pass-through superconducting rock magnetometers (SRM) has greatly
promoted collection of paleomagnetic data from continuous long-core samples. The output of pass-through
measurement is smoothed and distorted due to convolution of magnetization with the magnetometer
sensor response. Although several studies could restore high-resolution paleomagnetic signal through
deconvolution of pass-through...
Numerous populations of salmon and trout undergo extensive migrations, migrating from freshwater to the sea and throughout ocean basins. Years later they return to their natal streams with remarkable accuracy and precision. The outward migration is accomplished without the benefit of following experienced migrants or prior individual experience. Evidence suggests...
We carried out a detailed rock magnetic and paleomagnetic study of deep-sea sediments from selected intervals of Site 1233 in order to assess whether they contain reproducible evidence for submillennial-scale environmental, climatic, and geomagnetic field variability. Three 1.5-m sediment intervals from oxygen isotope Stages 1, 2, and 3 were sampled...
Ninety-five oriented samples were obtained from nine Recent
Cascade lava flows in Oregon. Directions and intensities of remanent
magnetization were measured on a spinner magnetometer which measures
directions of magnetization to within 1.2° s.d. Angle measurements
were plotted graphically using an equal area projection. Mean
directions and statistics were calculated...
Investigations of the behavior of the geomagnetic field on geological timescales rely on globally
distributed data sets from dated lava flows. We present the first suitable data from the Arctic region,
comprising 37 paleomagnetic directions from Jan Mayen (71°N, 0.2–461 ka) and Spitsbergen (79°N, 1–9.2 Ma) and five paleointensity results....
Full Text:
variation; Jan Mayen; Spitsbergen; geomagnetic field.
Index Terms: 1522 Paleomagnetic secularvariation
A new model of long-period tidal variations in length of day is developed. The model
comprises 80 spectral lines with periods between 18.6 years and 4.7 days, and it consistently includes effects
of mantle anelasticity and dynamic ocean tides for all lines. The anelastic properties follow Wahr and Bergen;
experimental...
The issue of permanent nondipole contributions to the time-averaged field lies at the very heart of
paleomagnetism and the study of the ancient geomagnetic field. In this paper we focus on paleomagnetic
directional results from igneous rocks of the southwestern U.S.A. in the age range 0–5 Ma and investigate
both...
Paleomagnetic analysis and radiocarbon dating of an expanded Holocene deep-sea sediment sequence
recovered by Integrated Ocean Drilling Program (IODP) Expedition 303 from Labrador Sea Site U1305
(Lat.: 57°28.5 N, Long.: 48°31.8 W, water depth 3459 m) provides insights into mechanisms that drive
both paleomagnetic secular variation (PSV) and magnetization acquisition...
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secularvariation (PSV) and magnetization acquisition in deep-sea sediments.
Seventeen radiocarbon dates
Paleomagnetic analysis and radiocarbon dating of an expanded Holocene deep-sea sediment sequence
recovered by Integrated Ocean Drilling Program (IODP) Expedition 303 from Labrador Sea Site U1305
(Lat.: 57°28.5 N, Long.: 48°31.8 W, water depth 3459 m) provides insights into mechanisms that drive
both paleomagnetic secular variation (PSV) and magnetization acquisition...
Paleomagnetic analysis and radiocarbon dating of an expanded Holocene deep-sea sediment sequence
recovered by Integrated Ocean Drilling Program (IODP) Expedition 303 from Labrador Sea Site U1305
(Lat.: 57°28.5 N, Long.: 48°31.8 W, water depth 3459 m) provides insights into mechanisms that drive
both paleomagnetic secular variation (PSV) and magnetization acquisition...
Continental flood basalts represent short-lived but immense blasts of mafic magma to the continental crust. The youngest and smallest continental flood basalt worldwide, the Columbia River Basalt, initiated with the eruption of the most mafic member, the Steens Basalt (~16.9 Ma). The Steens Basalt is exposed in southeast Oregon, southwest...
Burial Lake sediments from the Noatak Basin in the northwest Brooks Range of Arctic Alaska (68.43°N, 159.17°W, 21.5 m water depth) provide the oldest continuous lacustrine record of paleo-environmental change and paleomagnetic secular variation (PSV) in eastern Beringia. A precise radiocarbon chronology, determined through accelerator mass spectrometry (AMS) allows us...
The submarine Amsterdam-St. Paul (ASP) Plateau, bisected by the Southeast Indian Ridge (SEIR), is a bathymetric high rising ~2 km above the surrounding seafloor that includes the islands of Amsterdam and St. Paul; this excess volcanism is attributed to a mantle hot spot. We obtained new Sr, Nd, and Pb...
In spite of the rapid economic growth of the post-war era, there
has not been significant improvement in the incidence of poverty,
nor in the inequality of income distribution around the world, and
particularly in the developing countries. A reason for the apparent
failure of the poor to benefit from...
Research Objective: Nearly 60 million people in the United States reside in a rural area. Residents in rural areas have higher rates of chronic disease, risky health behaviors, disability, infant mortality, and age-adjusted mortality than their urban counterparts. Health insurance and access to care mitigate those risks, in part because...
The Roza flow of the Columbia River Basalt group in
Washington State U.S.A. extruded at about 15 Ma during
intermediate geomagnetic polarity. The Roza is underlain
by normal polarity flows and overlain by reversed units.
The Roza is an extensive flow, up to 60 in thick. As the
remanence-blocking isotherms...
Magnetotelluric (MT) data from two sites 150 and
300 km southeast of San Francisco, California (geomagnetic
dipole latitude: 43 degrees, L approximately 1.9) show that
the usual MT assumption of spatially uniform external magnetic
fields is violated to a significant degree in the period
range 10-30 s. Inter-station transfer functions...
Full Text:
in Mid‐Latitude Geomagnetic Transfer Functions” by Gary D. Egbert, Markus Eisel, O
Magnetotelluric (MT) data from two sites 150 and
300 km southeast of San Francisco, California (geomagnetic
dipole latitude: 43 degrees, L approximately 1.9) show that
the usual MT assumption of spatially uniform external magnetic
fields is violated to a significant degree in the period
range 10-30 s. Inter-station transfer functions...
Full Text:
Geomagnetic Transfer Functions
GEOPHYSICAL RESEARCH LETTERS, VOL. 27, NO. 1, PAGES 25-28, JANUARY 1, 2000
The deglacial behavior of the sub-Arctic North Pacific is poorly constrained, with many published records suffering from limited age control due to extensive post- depositional biogenic carbonate dissolution. Potential alternative dating methods could include the correlation of stable-isotopic and/or paleomagnetic secular variation records to an independently-dated regional template, however no...
Sedimentary records from the North Atlantic, instrumental in the development of modern paleo-geomagnetic concepts, show a highly variable field even during times of constant polarity. Yet, our understanding of how the magnetization is acquired in the sediments is poorly understood. Primary magnetizations preserved in deep-sea sediments are known to be...
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3 North Atlantic paleomagnetic secularvariation and relative paleomagnetic intensity
over the
We report the intercalibration of paleomagnetic secular variation (PSV) and expanded postglacial sediment cores from geographically proximal, but sedimentologically contrasting settings. The objective is to improve relative what can be achieved with either method alone. Core MD99-2269 was taken from north Iceland shelf. Core MD99-2322 was collected from the Kangerlussuaq...
We report paleointensity results of the Earth's
magnetic field from n Late Pleistocene lava flow
(Louchadiere, Central France), which recorded an intermediate
geomagnetic field direction (5 sites, mean declination=
114.1°, inclination=58.2°, k=130, α95=6.7°). New K-Ar
age determinations confirm that this flow is contemporaneous
with the Laschamp and Olby flows, and...
Investigations of the behavior of the geomagnetic field on geological timescales rely on globally
distributed data sets from dated lava flows. We present the first suitable data from the Arctic region,
comprising 37 paleomagnetic directions from Jan Mayen (71°N, 0.2–461 ka) and Spitsbergen (79°N, 1–9.2 Ma) and five paleointensity results....
Ontogenetic niche theory predicts that as organisms grow they make size-specific changes in habitat use and diet to optimize growth and survival. A variety of factors contribute to growth and survival in different habitats, ultimately leading to variation in life history that can affect population dynamics. An understanding of the...
Eleven years (1932-1942) of electric potential and magnetic measurement at the Tucson observatory
represent a unique very long period magnetotelluric (MT) data set. We report here on a careful reanalysis of this
data using modern processing techniques. We have developed and used novel methods for separating out the
quasi-periodic daily...
Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene
Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The...
Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene
Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The...
Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene
Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The...
Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene
Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The...
Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene
Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The...
Observations of Earth’s magnetic field extending back to 3.45 billion years ago indicate that generation by a core dynamo must be sustained over most of Earth’s history. However, recent estimates of thermal and electrical conductivity of liquid iron at core conditions from mineral physics experiments indicate that adiabatic heat flux...
Present GEK (Geomagnetic Electrokinetograph) theory is extended
to include internal waves of the lowest mode. The predicted
towed electrode GEK signal is determined to second-order for long-crested
internal waves in a finite but deep ocean. The analysis includes
the determination of GEK signatures for small amplitude and
finite amplitude interfacial...
The importance of language and bilinguality in the
development, perpetuation, and "degeneration" or change of
culture is a central theme throughout this treatise.
Original pictorial representations of Mayan hieroglyphic
sculpture are included as examples, and represent artistic
styles and language variations of written Cholan and
Yucatec. Modern Cholan and Yucatecan...
The current satellite magnetic missions offer new
opportunities to determine the electrical conductivity of the
Earth. However, satellites are nearly stationary in local time
and therefore sample the inducing and induced fields quite
differently than geomagnetic observatories, which rotate
with the Earth. We show that estimates of induction transfer
functions...
This research presents a u-channel based study of the natural remanent magnetization (NRM), the laboratory magnetization, Anhysteretic Remanent Magnetization (ARM), and magnetic susceptibility (k), from the upper 100 m of International Ocean Discovery Program (IODP) Expedition 383 Site U1543 in the eastern South Pacific sector of the Southern Ocean. Alternating...
Global electromagnetic (EM) induction studies have been the focus of increasing attention during the past few years. A primary stimulus for this interest has been increased quality, coverage and variety of the newly available data sets especially from recent low-Earth-orbiting satellite missions. The combination of traditional ground-based data with satellite-borne...
Magneto- and chemostratigraphic correlation underpins much of our understanding of Earth history, yet typical correlation techniques are neither quantitative nor objective. Within this dissertation, I detail my efforts to develop and apply dynamic programming-based algorithms that accomplish optimal and reproducible stratigraphic alignment. I apply these algorithms to three geologic intervals:...
Although satellite electromagnetic induction studies
have usually assumed a symmetric magnetospheric ring
current source, there is growing evidence for significant
source asymmetry. Here we apply empirical orthogonal
function methods to mid-latitude night-side hourly mean
geomagnetic observatory data to search for evidence of nonzonal
low-frequency source fields. The dominant spatial
mode...
Ground level electric fields arising from geomagnetic disturbances (GMDs) are used by the electric power industry to calculate geomagnetically induced currents (GICs) in the power grid. Current industry practice is limited to electric fields associated with 1‐D ground electrical conductivity structure, yet at any given depth in the crust and...
During the North Pacific cruise of the R/V Yaquina in 1966,
total magnetic field intensity was measured in the Andreanof group
of the Aleutian Islands. Three north-south track lines were made
across the Aleutian Trench and ridge between longitudes 175° W
and 180°.
Three small scale magnetic profiles across the...
We present a decade-long (1981–1990) high-resolution (subseasonal) record of Pb and Cd concentrations and Pb isotopic composition in a series of 119 snow samples from a 6-m snow pit at Summit, Greenland. Both metals show order of magnitude seasonal variability, with maxima in spring of every year, coinciding with sulfate...
More than 7 km of long and relatively continuous sediment sequences
from 11 sites in the southeast and equatorial Pacific were recovered
during Leg 202 for the study of the Earth’s climate and biogeochemical
systems on scales that range from tectonic (millions of
years) to orbital (tens to hundreds of...
We report the construction of a three-dimensional template bank for the search for gravitational waves
from inspiralling binaries consisting of spinning compact objects. The parameter space consists of two
dimensions describing the mass parameters and one “reduced-spin” parameter, which describes the secular
(nonprecessing) spin effects in the waveform. The template...
This research was aimed at providing the foundation for changing standards of care in a critical care setting using Catholic concepts of respect for human dignity, subsidiarity, common good, and solidarity as a matter of social justice. I first unpacked the nature of ICU care and the inevitability of the...
The long-term timber supply situation in North America is in a tremendous state of transition. Although short-term demand and price projections are extremely important in the development of near-term strategy and business planning, long-range strategic planning should be developed using long-term projections, or secular trends, of timber demand and supply....
We investigate in this thesis, the problem of stability
of thermo-viscoelastic fluid flow between rotating
coaxial cylinders. By using the thermo-viscoelastic
constitutive equations given by Eringen, we reduce the
equations of motion into a form suitable for stability
analysis. The course of reduction which we follow yields
some interesting intermediate...
Geomagnetically Induced Currents (GICs) are quasi-DC signals that are induced in the ground during geomagnetic disturbances (GMDs) and pose a large threat to power grid infrastructure. The power industry currently attempts to mitigate GIC effects by utilizing 1-D ground electrical conductivity based electric field predictions, though conductivity can vary in...
With advancing computational resources, 3-D inversion techniques have become feasible in recent years and are now a more widely used tool for magnetotelluric (MT) data interpretation. Galvanic distortion caused by small-scale near-surface inhomogeneities remains an obstacle for 3-D MT inversion which so far has experienced little attention. If not considered...
We describe novel hybrid algorithms for inversion of electromagnetic geophysical data, combining the computational and storage efficiency of a conjugate gradient approach with an Occam scheme for regularization and step-length control. The basic algorithm is based on the observation that iterative solution of the symmetric (Gauss-Newton) normal equations with conjugate...
We describe a new algorithm for robust principal component analysis (PCA) of electromagnetic (EM) array data, extending previously developed multivariate methods to include arrays with large data gaps, and only partial overlap between site occupations. Our approach is based on a criss-cross regression scheme in which polarization parameters and spatial...
Spectral analysis of the time-varying horizontal magnetic and electric field components yields the magnetotelluric (MT) impedance tensor. This frequency dependent 2x2 complex tensor can be examined for details which axe diagnostic of the electrical conductivity distribution in the Earth within the relevant (frequency dependent) inductive scale length of the surface...
By inverting EarthScope long-period magnetotelluric (MT) data from the southeastern United States (SEUS), we obtain electrical conductivity images that provides key insights into the geodynamics of this region. Significantly, we resolve a highly electrically resistive block that extends to mantle depths beneath the modern Piedmont and Coastal Plain physiographic provinces....
A study was made of the infrared absorption spectrum for
cyanate ion in KCl and KBr host lattices containing small amounts of
calcium or barium ion. Both pellets and single crystals were
scanned during the course of this study. The spectra of the barium
or calcium doped crystals contained many...
A magnetotelluric (MT)transect has been obtained near latitude 45øN from the active Juan de Fuca
Spreading center, across the subduction zone and Cascades volcanic arc, and into the back arc Deschutes
Basin region. This paper presents the MT data set and describes its major characteristics as they pertain to
the...
Constraining the development, evolution, and timescales of large silicic magma systems is important to understanding the development of granite batholiths, the relationships between volcanoes and their plutonic underpinnings, and the development of the continental crust.
The ignimbrite flare up that produced the Altiplano-Puna Volcanic Complex of the Central Andes is...
Disentangling sediment source from sediment transport is a fundamental marine geologic challenge critical to the interpretation of any sedimentary record. The Eirik Ridge, a sediment drift south of Greenland, receives terrigenous sediment primarily from subglacial erosion of south Greenland’s Precambrian bedrock and Paleogene volcanics that outcrop in east Greenland and...
In a companion paper (Egbert et al., this issue) we describe the estimation of very long period (0.16 < T < 91 days) magnetotelluric (MT) impedances from 11 years of data collected at the Tucson geomagnetic observatory. Here we discuss the implications of these data for mantle conductivity. Using minimum...
Large ignimbrite flare-ups provide records of profound crustal modification during batholith formation at depth. The locations of source calderas and volumes and ages of the eruptions must be determined to develop models for the tectonomagmatic processes that occur during these events. Although high-precision isotopic ages of the ignimbrites are critical,...
Marine magnetic data from the northern Yucatan continental margin were used to
obtain the radially-averaged power-density spectra (RAPDS) of 34 grids, each with
dimensions of 128 by 128 km, overlapping 50 percent. Depths to the tops of three
magnetic horizons were estimated from the slopes of linear segments in the...
Combined analyses of deep tow magnetic anomalies and International Ocean Discovery Program Expedition 349 cores show that initial seafloor spreading started around 33 Ma in the northeastern South China Sea (SCS), but varied slightly by 1-2 Myr along the northern continent-ocean boundary (COB). A southward ridge jump of ∼20 km...
Magnetic, gravity and bathymetry data were collected on an extended
cruise of the R/V Yaquina in 1969. The last set of data was obtained
from those track lines leaving the Panama Basin. The area
covered is mainly the Cocos plate (Molnar and Sykes, 1969). The data
is analyzed and compared...
The Last Interglacial (LIG) represents an invaluable case study to investigate the response of components of the Earth system to global warming. However, the scarcity of absolute age constraints in most archives leads to extensive use of various stratigraphic alignments to different reference chronologies. This feature sets limitations to the...
Full Text:
234U/238U ratio (in delta notation, relative to the secular
equilibrium value of 1) of authigenic U for
This investigation focuses on gaining a better understanding of the complex relationship between melt generation, source variability and mid-ocean ridge morphology. The approach adopted here uses a variety of geochemical techniques to evaluate the ability of 'global' models to predict regional scale geochemical variability associated with axial depth and axial...
Bulk magnetic properties of soils and sediments are often sensitive proxies for environmental change but commonly require interpretation in terms of the different sources of magnetic minerals (or components) that combine to generate them. Discrimination of different components in the bulk magnetic record is often attempted through endmember unmixing and/or...
We present new age determinations, derived from ⁴⁰Ar–³⁹Ar incremental heating experiments, for basaltic lava flows from the Mandla lobe, located on the eastern margin of the main Deccan volcanic province, some ~ 1000 km from the Western Ghats escarpment. The most reliable estimates of crystallization ages come from 5 plateau...
The development of pass-through superconducting rock magnetometers (SRM) has greatly
promoted collection of paleomagnetic data from continuous long-core samples. The output of pass-through
measurement is smoothed and distorted due to convolution of magnetization with the magnetometer
sensor response. Although several studies could restore high-resolution paleomagnetic signal through
deconvolution of pass-through...
Full Text:
-through magnetometer: A new algorithm to restore geomagnetic and environmental information based on
We used simulated magnetic displacements to test orientation preferences of
juvenile steelhead trout (Oncorhynchus mykiss) exposed to magnetic fields
existing at the northernmost and southernmost boundaries of their oceanic
range. Fish reared in natural magnetic conditions distinguished between
these two fields by orienting in opposite directions, with headings that
would...
Full Text:
Compatibility of
magnetic imprinting and secularvariation. Curr. Biol.
18, R596–R597. (doi:10.1016/j.cub
In this thesis anomalous downcore shallowing of paleomagnetic
inclinations is interpreted to be caused by sediment compaction. Thus,
compaction-induced inclination shallowing may influence tectonic
reconstructions that are based on inclinations from deep-sea sediment
cores.
Progressive downcore shallowing of the remanent inclination was
observed in a 120-m section of Plio- Pleistocene...
We use data from a series of small (three to five stations) overlapping magnetovariational (MV) arrays to image variations of vertically integrated electrical conductivity in the crust of southwestern Washington. Two principal structures are revealed: a large north-south trending anomaly (the southern Washington Cascades Conductor (SWCC), which has been detected...
Electric and magnetic fields in the (10−4–1.0) Hz band were monitored at two sites
adjacent to the San Andreas Fault near Parkfield and Hollister, California, from 1995 to
2007. A data window (2002–2005), enclosing the 28 September 2004 M6 Parkfield
earthquake, was analyzed to determine if anomalous electric or magnetic...
The Russian Old Believers in Oregon maintain a manner of dress which distinguishes them in the communities in which they live. Originating as a group because of a schism within the Russian Orthodox Church in 1666, the Russian Old Believers migrated to the edge of the Russian Empire and beyond...
Paleomagnetic directions from the Eocene Tillamook Volcanic Series of the Oregon Coast Range
point 460 clockwise from the expected Eocene field direction. Potassium argon dating of six dikes and
flows from this formation yields a mean age of 44.3 ± 0.6 m.y. These results establish that the Oregon
coastal block...
The thermobaric nonlinearity in the equation of state for seawater density—namely, the dependence of thermal expansibility on pressure—coupled with spatial variation of the oceanic temperature–salinity (θ–s) relation generates a nonlinear behavior in the buoyant force that can counter the linear dispersion of baroclinic Rossby waves and produce solitary waves. A...
The ongoing retreat of glaciers globally is one of the clearest manifestations of recent global warming associated with rising greenhouse gas concentrations. By comparison, the importance of greenhouse gases in driving glacier retreat during the most recent deglaciation, the last major interval of global warming, is unclear due to uncertainties...
Full Text:
, L. & King, J. W. A late quaternary geomagneticsecularvariation
record from Lake Waiau, Hawaii, and
Ocean Drilling Program (ODP) Leg 202 has opened a new window
into understanding late Paleogene and Neogene global environmental
change by providing high-quality sediment sequences from a previously
unsampled region, the eastern South Pacific. Eleven sites (1232–
1242) that record variations on timescales ranging from decades to tens
of millions...
The Oregon Wave Energy Trust (OWET) commissioned this study to develop protocols and
methods to achieve affordable, reliable, and repeatable electromagnetic (EM) measurements in
the near-shore environment. The study was conducted in several stages, with a number of
technical reports provided at each stage to document and describe findings. The...
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sea currents traveling through the geomagnetic field. Anthropogenic sources of
EMF emissions in the
This compilation lists in chronological order the oceanographic reports published in 1972, 1973 and 1974. It is an update of our reference 74-1 which brought together a listing all the numbered series issued, 1955-1973. It also lists theses for which degrees were awarded in 1974. A theses listing for 1962-1973...
Magnetotellurics is used in two geologic settings on scales ranging from 1000-km tectonic structures to local features hundreds of meters wide. These areas are the Midcontinent Rift System (MRS) and its related mantle plume in the northern Midwestern United States and Newberry Volcano in central Oregon.
The MRS study uses...
Semi-volatile trace metals like Li, Cu, Mo, Sn, In, and Pb have the potential to track mobility of a volatile phase in volcanic systems. In this dissertation four studies are presented that either directly investigate or are motivated by observations of trace metal behavior in volcanic systems. A common tool...
Ionospheric scintillation occurs mainly at high and low latitude regions of the Earth and may impose serious degradation on GNSS (Global Navigation Satellite System) functionality. The Brazilian territory sits on one of the most affected areas of the globe, where the ionosphere behaves very unpredictably, with strong scintillation frequently occurring...
Power spectral analysis using the maximum entropy method is
applied to the estimation of depth to the source of magnetic anomalies.
The method assumes that the source is two-dimensional and has a
magnetization with random intensity. The predictive ability of the
maximum entropy technique permits analysis of short segments of...
