Paleomagnetic Records of Meteorites and Early Planetesimal Differentiation

Weiss, B. P.; Gattacceca, J.; Stanley, Sabine; Rochette, P.; Christensen, Ulrich R.

doi:10.1007/978-1-4419-5901-0_11

Cited by 36 publications

(59 citation statements)

References 208 publications

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“…(f ), and P Sp (f ) given as in (23), (24), and (25) showing that the decomposition in (21) exists as a sum. On the other hand, we obtain formula (23) by observing in view of (17) …”

Section: Potentials As Poisson Integralsmentioning

confidence: 98%

“…It can also be used to study processes other than those of geomagnetism, including characterizing past motions of tectonic plates and as a relative chronometer through the identification of geomagnetic reversals (periods when the Earth's north and south magnetic poles are interchanged) in rock sequences [17]. Rocks from Mars, the Moon, and asteroids are also known to contain remanent magnetization which indicates the past presence of core dynamos on these bodies [1,7,25]. Magnetization in meteorites may even record magnetic fields produced by the young sun and the protoplanetary disk (the primordial nebula of gas and dust around the young sun), which may have played a key role in solar system formation [25].…”

Section: Introductionmentioning

confidence: 99%

“…Rocks from Mars, the Moon, and asteroids are also known to contain remanent magnetization which indicates the past presence of core dynamos on these bodies [1,7,25]. Magnetization in meteorites may even record magnetic fields produced by the young sun and the protoplanetary disk (the primordial nebula of gas and dust around the young sun), which may have played a key role in solar system formation [25].…”

Section: Introductionmentioning

confidence: 99%

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Characterizing kernels of operators related to thin-plate magnetizations via generalizations of Hodge decompositions

Baratchart¹,

Hardin²,

Lima³

et al. 2012

Inverse Problems

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Abstract. Recently developed scanning magnetic microscopes measure the magnetic field in a plane above a thin-plate magnetization distribution. These instruments have broad applications in geoscience and materials science, but are limited by the requirement that the sample magnetization must be retrieved from measured field data, which is a generically nonunique inverse problem. This problem leads to an analysis of the kernel of the related magnetization operators, which also has relevance to the "equivalent source problem" in the case of measurements taken from just one side of the magnetization. We characterize the kernel of the operator relating planar magnetization distributions to planar magnetic field maps in various function and distribution spaces (e.g., sums of derivatives of L p (Lebesgue spaces) or bounded mean oscillation (BMO) functions). For this purpose, we present a generalization of the Hodge decomposition in terms of Riesz transforms and utilize it to characterize sources that do not produce magnetic field either above or below the sample, or that are magnetically silent (i.e., no magnetic field anywhere outside the sample). For example, we show that a thin-plate magnetization is silent (i.e., in the kernel) when its normal component is zero and its tangential component is divergence-free. In addition, we show that compactly supported magnetizations (i.e., magnetizations that are zero outside of a bounded set in the source plane) that do not produce magnetic fields either above or below the sample are necessarily silent. In particular, neither a nontrivial planar magnetization with fixed direction (unidimensional) compact support nor a bidimensional planar magnetization (i.e., a sum of two unidimensional magnetizations) that is nontangential can be silent. We prove that any planar magnetization distribution is equivalent to a unidimensional one. We also discuss the advantages of mapping the field on both sides of a magnetization, whenever experimentally feasible. Examples of source recovery are given along with a brief discussion of the Fourier-based inversion techniques that are utilized.

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“…(f ), and P Sp (f ) given as in (23), (24), and (25) showing that the decomposition in (21) exists as a sum. On the other hand, we obtain formula (23) by observing in view of (17) …”

Section: Potentials As Poisson Integralsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Characterizing kernels of operators related to thin-plate magnetizations via generalizations of Hodge decompositions

Baratchart¹,

Hardin²,

Lima³

et al. 2012

Inverse Problems

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“…Convection on these bodies is currently thought to have been thermally driven 7,8 , implying that magnetic activity would have been short-lived 9 . Here we present a time-series paleomagnetic record of the field recorded by the Imilac and Esquel pallasite meteorites, derived from nanomagnetic images 10 of their metallic matrices.…”

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confidence: 99%

Long-lived magnetism from solidification-driven convection on the pallasite parent body

Bryson

Nichols

Herrero‐Albillos

et al. 2015

Nature

151

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Paleomagnetic measurements of meteorites 1-5 suggest that, shortly after the birth of the solar system, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields 6 . Convection on these bodies is currently thought to have been thermally driven 7,8 , implying that magnetic activity would have been short-lived 9 . Here we present a time-series paleomagnetic record of the field recorded by the Imilac and Esquel pallasite meteorites, derived from nanomagnetic images 10 of their metallic matrices. The results reveal a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shut down of the magnetic field. We demonstrate that magnetic activity driven by progressive solidification of an inner core 11-13 is consistent with our measured magnetic field characteristics and cooling rates 14 . Solidification-driven convection was likely common among small body cores 15 , and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early solar system.The pallasites are slowly cooled (2 -9 K Myr -1 ) 14 stony-iron meteorites 16 , which originated from the mid-to upper-mantle of a ~200-km-radius body 1 . The slow cooling rate of these meteorites allowed for characteristic microstructures to form in their metal matrix 17 , a key feature of which are regions of intergrown nanoscale islands of tetrataenite (ordered FeNi) 18,19 and an ordered Fe 3 Ni matrix 20 , collectively known as cloudy zones (CZ) 21 . During parent body cooling, these tetrataenite islands exsolved and subsequently coarsened over tens of millions of years 22 . The island diameter decreases systematically across the CZ, reflecting a decrease in the local formation age of the islands 20 . Each island adopted one of three orthogonal magnetic easy axes as it formed 18,23 , thus could display any one of six magnetisation directions. Variations in the intensity and direction of an external magnetic field led to measurable differences in the populations of each magnetisation direction 20 . Crucially, the temporal evolution of an external field is recorded by the variations in the relative proportions of these directions across the CZ 10 , which can be quantified using high-resolution nanomagnetic imaging. These images were captured for the Imilac and Esquel pallasites, utilising X-ray magnetic circular dichroism 24,25 at the X-ray photoemission electron microscope (XPEEM) 26 at the BESSY II synchrotron, Berlin, which provides the spatially resolved magnetisation of a sample surface with a resolution down to 40 nm over a 5 µm field-of-view 10 .Four and six non-overlapping, 450-nm-wide regions across the CZ (decreasing age) were extracted from the XPEEM images of Imilac and Esquel meteorites, respectively (Fig. 1). The field recorded by each region was deduced by comparing the experimental XPEEM sig...

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“…System-scale magnetic fields are observed to develop in galaxies, stars, planets, moons and even asteroids [1][2][3][4]. In all these systems, magnetohydrodynamic dynamo action occurs via the conversion of the kinetic energy of flowing electrically-conductive fluids into magnetic field energy [3,5].…”

Section: Introductionmentioning

confidence: 99%

Canonical Models of Geophysical and Astrophysical Flows: Turbulent Convection Experiments in Liquid Metals

Ribeiro¹,

Fabre²,

Guermond³

et al. 2015

Metals

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Planets and stars are often capable of generating their own magnetic fields. This occurs through dynamo processes occurring via turbulent convective stirring of their respective molten metal-rich cores and plasma-based convection zones. Present-day numerical models of planetary and stellar dynamo action are not carried out using fluids properties that mimic the essential properties of liquid metals and plasmas (e.g., using fluids with thermal Prandtl numbers P r < 1 and magnetic Prandtl numbers P m 1). Metal dynamo simulations should become possible, though, within the next decade. In order then to understand the turbulent convection phenomena occurring in geophysical or astrophysical fluids and next-generation numerical models thereof, we present here canonical, end-member examples of thermally-driven convection in liquid gallium, first with no magnetic field or rotation present, then with the inclusion of a background magnetic field and then in a rotating system (without an imposed magnetic field). In doing so, we demonstrate the essential behaviors of convecting liquid metals that are necessary for building, as well as benchmarking, accurate, robust models of magnetohydrodynamic processes in P m P r < 1 geophysical and astrophysical systems. Our study results also show strong agreement between laboratory and numerical experiments, demonstrating that high resolution numerical simulations can be made capable of modeling the liquid metal convective turbulence needed in accurate next-generation dynamo models.

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Paleomagnetic Records of Meteorites and Early Planetesimal Differentiation

Cited by 36 publications

References 208 publications

Characterizing kernels of operators related to thin-plate magnetizations via generalizations of Hodge decompositions

Characterizing kernels of operators related to thin-plate magnetizations via generalizations of Hodge decompositions

Long-lived magnetism from solidification-driven convection on the pallasite parent body

Canonical Models of Geophysical and Astrophysical Flows: Turbulent Convection Experiments in Liquid Metals

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