A5083883713- Geomagnetism and Paleomagnetism Studies
- Geology and Paleoclimatology Research
- Geological and Geochemical Analysis
- Astro and Planetary Science
- Geological and Geophysical Studies
- Paleontology and Stratigraphy of Fossils
- Geophysical and Geoelectrical Methods
- Magnetic and Electromagnetic Effects
- Planetary Science and Exploration
- Drilling and Well Engineering
- Reservoir Engineering and Simulation Methods
- Geological Studies and Exploration
- Geophysics and Gravity Measurements
- earthquake and tectonic studies
- High-pressure geophysics and materials
- Geochemistry and Elemental Analysis
- Methane Hydrates and Related Phenomena
- Solar and Space Plasma Dynamics
- Geological formations and processes
- Hydrocarbon exploration and reservoir analysis
- Hydraulic Fracturing and Reservoir Analysis
- Paleontology and Evolutionary Biology
- Archaeology and Rock Art Studies
- Pleistocene-Era Hominins and Archaeology
- Geochemistry and Geologic Mapping
University of Rochester
2016-2025
Energetics (United States)
2022-2025
University of KwaZulu-Natal
2018-2020
Stanford University
1985-2009
University of Münster
2009
Ludwig-Maximilians-Universität München
2009
Environmental Earth Sciences
2007
Japan Agency for Marine-Earth Science and Technology
2003
University of Hawaii System
2003
Oregon State University
2003
The Hawaiian-Emperor hotspot track has a prominent bend, which served as the basis for theory that Hawaiian hotspot, fixed in deep mantle, traced change plate motion. However, paleomagnetic and radiometric age data from samples recovered by ocean drilling define an age-progressive paleolatitude history, indicating Emperor Seamount trend was principally formed rapid motion (over 40 millimeters per year) of plume during Late Cretaceous to early-Tertiary times (81 47 million years ago)....
Early Origin of Earth's Magnetic Field magnetic field protects us from stellar winds and radiation the Sun. Understanding when, during formation, large-scale was established is important because it impacts understanding young atmosphere exosphere. By analyzing ancient silicate crystals, Tarduno et al. (p. 1238 ; see Perspective by Jardine ) demonstrate that existed 3.4 to 3.45 billion years ago, pushing back oldest record geomagnetic strength 200 million years. This result combined with...
Unlocking Earth's ancient magnetic past The field protects surface from deadly cosmic radiation and provides clues about the planet's interior. Tarduno et al. found that some of oldest minerals on Earth, Jack Hills zircons, preserved a record over 4 billion years ago (see Perspective by Aubert). appears to have been fully operational mere few hundred million after planet formed. This suggests an early start for plate tectonics shield was important habitability Science , this issue p. 521 ; see also
The timing of flood basalt volcanism associated with formation the Ontong Java Plateau (OJP) is estimated from paleomagnetic and paleontologic data. Much OJP formed rapidly in less than 3 million years during early Aptian, at beginning Cretaceous Normal Polarity Superchron. Crustal emplacement rates are inferred to have been several times those Deccan Traps. These estimates consistent an origin by impingement base oceanic lithosphere head a large mantle plume. Formation may led rise sea...
A Late Cretaceous (92 to 86 million years ago) vertebrate assemblage from the high Canadian Arctic (Axel Heiberg Island) implies that polar climates were warm (mean annual temperature exceeding 14 degreesC) rather than near freezing. The includes large (2.4 meters long) champsosaurs, which are extinct crocodilelike reptiles. Magmatism at six igneous provinces this time suggests volcanic carbon dioxide emissions helped cause global warmth.
Bends in volcanic hotspot lineaments, best represented by the large elbow Hawaiian-Emperor chain, were thought to directly record changes plate motion. Several lines of geophysical inquiry now suggest that a change locus upwelling mantle induced dynamics causes bends tracks. Inverse modeling suggests although deep flow near core-mantle boundary may have played role bend, capture plume ridge, followed sub-Pacific flow, can better explain observations. Thus, tracks reveal patterns past circulation.
Understanding the origin of pallasites, stony-iron meteorites made mainly olivine crystals and FeNi metal, has been a vexing problem since their discovery. Here, we show that pallasite olivines host minute magnetic inclusions have favorable recording properties. Our paleointensity measurements indicate strong paleomagnetic fields, suggesting dynamo action in parent body. We use these data thermal modeling to suggest some pallasites formed when liquid from core an impactor was injected as...
The dramatic decay of dipole geomagnetic field intensity during the last 160 years coincides with changes in Southern Hemisphere (SH) morphology and has motivated speculation an impending reversal. Understanding these changes, however, been limited by lack longer-term SH observations. Here we report first archaeomagnetic curve from southern Africa (ca. 1000–1600 AD). Directions change relatively rapidly at ca. 1300 AD, whereas intensities drop sharply, a rate greater than modern Africa, to...
Determining the age of geomagnetic field is paramount importance for understanding evolution planet because shields atmosphere from erosion by solar wind. The absence or presence also provides a unique gauge early core conditions. Evidence 4.2 billion-year (Gy) old, just few hundred million years after lunar-forming giant impact, has come paleomagnetic analyses zircons Jack Hills (Western Australia). Herein, we provide new and electron microscope that attest to primary magnetic remanence...
Plate tectonics is a fundamental factor in the sustained habitability of Earth, but its time onset unknown, with ages ranging from Hadaean to Proterozoic eons1-3. motion key diagnostic distinguish between plate and stagnant-lid tectonics, palaeomagnetic tests have been thwarted because planet's oldest extant rocks metamorphosed and/or deformed4. Herein, we report palaeointensity data Hadaean-age Mesoarchaean-age single detrital zircons bearing primary magnetite inclusions Barberton...
The bend in the Hawaiian-Emperor chain is best example of a change plate motion recorded fixed-hotspot frame reference. Alternatively, might record primarily differences Hawaiian hotspot relative to Pacific lithosphere. New paleomagnetic data from Emperor support latter view. Althouth rate difficult constrain because uncertainties posed by true polar wander and limited sampling chain, available suggest hotspots may have moved at rates comparable those lithospheric plates (> 30 mm yr−1) late...
The basic features of the geomagnetic reversal chronology last 160 million years are well established. relationship between this history and other field, however, has been elusive. determination past field strength (paleointensity) is especially challenging. Commonly accepted results have come from analyses bulk samples lava. Historic lavas shown to faithfully record when analyzed using Thellier double‐heating method. Data older lavas, tend show effects in situ laboratory‐induced alteration....
If relationships exist between the frequency of geomagnetic reversals and morphology, secular variation, intensity Earth's magnetic field, they should be best expressed during superchrons, intervals tens millions years long lacking reversals. Here we report paleomagnetic paleointensity data from lavas Cretaceous Normal Polarity Superchron that formed at high latitudes near tangent cylinder surrounds solid inner core. The time-averaged field recorded by these is remarkably strong stable. When...
The convergence between the Pacific, Farallon, and Kula oceanic plates North American plate has provided a driving force for tectonic processes that have shaped western margin of America. Yet reconstructions motion in Pacific basin traditionally relied on assumption fixed hot spots. In last decade, substantial Cretaceous to Paleogene Atlantic spots been recognized, providing motivation reevaluate history relative America by means circuit reconstructions. This paper presents new kinematic...
The onset and nature of the earliest geomagnetic field is important for understanding evolution core, atmosphere life on Earth. A record early geodynamo preserved in ancient silicate crystals containing minute magnetic inclusions. These data indicate presence a during Paleoarchean, between 3.4 3.45 billion years ago. While sheltered Earth's from erosion at this time, standoff solar wind was greatly reduced, similar to that modern extreme storms. conditions suggest intense radiation young Sun...
Data on the evolution of Earth's magnetic field intensity are important for understanding geodynamo and planetary evolution. However, paleomagnetic record in rocks may be adversely affected by many physical processes, which must taken into account when analysing palaeointensity database. This is especially light an ongoing debate regarding core thermal conductivity values, how these relate to Precambrian geodynamo. Here, we demonstrate that several data sets database overestimate true...
Abstract Paleomagnetism can elucidate the origin of inner core structure by establishing when crystallization started. The salient signal is an ultralow field strength, associated with waning thermal energy to power geodynamo from core-mantle heat flux, followed a sharp intensity increase as new and compositional sources buoyancy become available once nucleation (ICN) commences. Ultralow fields have been reported Ediacaran (~565 Ma) rocks, but transition stronger strengths has unclear....
Abstract Earth’s magnetic field was in a highly unusual state when macroscopic animals of the Ediacara Fauna diversified and thrived. Any connection between these events is tantalizing but unclear. Here, we present single crystal paleointensity data from 2054 591 Ma pyroxenites gabbros that define dramatic intensity decline, strong Proterozoic like today, to an Ediacaran value 30 times weaker. The latter weakest time-averaged known date together with other robust estimates indicate ultra-low...