Magnetic classification of stony meteorites: 2. Non‐ordinary chondrites

Rochette, P.; Gattacceca, J.; Bonal, L.; Bourot-Denise, M.; Chevrier, V. F.; Clerc, Jean-Pierre; Consolmagno, G. J.; Folco, Luigi; Gounelle, M.; Kohout, T.; Pesonen, L. J.; Quirico, E.; Sagnotti, Leonardo; Skripnik, A. Ya.

doi:10.1111/j.1945-5100.2008.tb01092.x

Cited by 76 publications

(87 citation statements)

References 51 publications

(85 reference statements)

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“…Magnetic susceptibility measurements for this meteorite are consistent with CK chondrites (Rochette et al, 2008). It contains numerous chondrules in a medium-gray finegrained matrix (Marlow and Mason, 1993a).…”

Section: A4 Dav 92300 (Ck4; Weathering Grade A/b)supporting

confidence: 54%

Spectral reflectance properties of carbonaceous chondrites: 7. CK chondrites

Cloutis

Hudon

Hiroi

et al. 2012

Icarus

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a b s t r a c tThe reflectance spectra of 15 CK chondrites have been measured as part of an ongoing study of carbonaceous chondrite reflectance spectra. The available sample suite includes multiple grain sizes and samples with petrologic grades varying from CK4 to CK6. CK reflectance spectra are all characterized by an olivineassociated absorption band in the 1.05 lm region. Compared to pure olivine, CK spectra are darker, have a more subdued olivine absorption band, and are often more blue-sloped. Reflectance at 0.56 lm varies from 9.6% to 22.5%, and olivine band depth varies from 6.7% to 31.0%, for powders that include the finest fraction. With increasing grain size, and exclusion of the finest fraction, CK spectra become darker and more blue sloped, while the olivine absorption band initially becomes deeper and then shallower. The presence of calcium-aluminum inclusions (CAIs), whose abundance varies widely in CKs, does not normally lead to the appearance of a well-defined absorption band in the 2.1 lm region, although the overall blue slope of many CKs is likely attributable to Fe-bearing spinel in CK CAIs. The only consistent spectral feature that relates to metamorphic grade is that CK6 spectra have uniformly deeper olivine absorption band than CK4-5.5 spectra. This could be related to various factors such as loss/aggregation of opaques that may accompany metamorphism. Comparison of CV and thermally metamorphosed carbonaceous chondrite to CK spectra suggests that metamorphism to between 1000 and 1200°C is required for CV spectra to match CK spectra; CV spectra are uniformly darker and have shallower olivine absorption bands than CK spectra.

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Section: A4 Dav 92300 (Ck4; Weathering Grade A/b)supporting

confidence: 54%

Spectral reflectance properties of carbonaceous chondrites: 7. CK chondrites

Cloutis

Hudon

Hiroi

et al. 2012

Icarus

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“…Pyrrhotite has a magnetic phase transition at ∼2.8 GPa (Rochette et al 2003a), meaning that pyrrhotite-bearing meteorites shocked above this pressures may have lost all or much of the record of their pre-shock remanent magnetization (Rochette et al 2001;Louzada et al 2007). This is particularly crucial for basaltic shergottites and Rumuruti chondrites in which pyrrhotite is the main remanence carrier (Rochette et al 2008(Rochette et al , 2009a and which have generally been shocked to pressures in excess of 5 GPa Fritz et al 2005). It is also relevant for carbonaceous chondrites that contain pyrrhotite (e.g., Allende) along with FeNi metal and magnetite.…”

Section: Shockmentioning

confidence: 98%

“…Rock magnetic studies reflect the destruction of primary ferromagnetic phases in finds (Rochette et al 2003b(Rochette et al , 2008(Rochette et al , 2009a. Progressive weathering often leads to a decrease in (K) from hot desert meteorite Daraj 014.…”

Section: Weatheringmentioning

confidence: 99%

“…The paleomagnetism of five bulk Rumuruti chondrites (all Antarctic finds) was studied by Gattacceca and Rochette (2004). All samples had a stable remanent magnetization mostly carried by pyrrhotite, with the exception of the magnetitebearing A-881988 meteorite (Rochette et al 2008). NRM normalization techniques indicated similar paleointensities around ∼5 µT.…”

Section: Rumuruti-like (R) Chondritesmentioning

confidence: 99%

“…The cubic iron oxide minerals of the magnetite-ulvöspinel series (commonly referred to collectively as titanomagnetite) are important ferromagnetic minerals in carbonaceous chondrites (Herndon et al 1976;Rochette et al 2008), angrites (Weiss et al 2008a), and some Martian meteorites (Rochette et al 2009a). Nearly stoichiometric magnetite (Fe 3−x Z x O 4 with x < 0.01-0.02 for a wide range of impurities Z) undergoes two transitions at low temperatures: (1) a magnetic transition at ∼130 K when the first magnetocrystalline anisotropy constant passes through zero and (2) a first-order phase transition at ∼119 K to a lowtemperature monoclinic structure.…”

Section: Inverse Thermoremanent Magnetizationmentioning

confidence: 99%

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Paleomagnetic Records of Meteorites and Early Planetesimal Differentiation

et al. 2009

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The large-scale compositional structures of planets are primarily established during early global differentiation. Advances in analytical geochemistry, the increasing diversity of extraterrestrial samples, and new paleomagnetic data are driving major changes in our understanding of the nature and timing of these early melting processes. In particular, paleomagnetic studies of chondritic and small-body achondritic meteorites have revealed a diversity of magnetic field records. New, more sensitive and highly automated paleomagnetic instrumentation and an improved understanding of meteorite magnetic properties and the effects of shock, weathering, and other secondary processes are permitting primary and secondary magnetization components to be distinguished with increasing confidence. New constraints on the post-accretional histories of meteorite parent bodies now suggest that, contrary to early expectations, few if any meteorites have been definitively shown to retain records of early solar and protoplanetary nebula magnetic fields. However, recent studies of pristine samples coupled with new theoretical insights into the possibility of dynamo generation on small bodies indicate that some meteorites retain records of internally generated fields. These results indicate that some planetesimals formed metallic cores and early dynamos within just a few million years of solar system formation.

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Preservation and detectability of shock‐induced magnetization

et al. 2015

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An understanding of the effects of hypervelocity impacts on the magnetization of natural samples is required for interpreting paleomagnetic records of meteorites, lunar rocks, and cratered planetary surfaces. Rocks containing ferromagnetic minerals have been shown to acquire shock remanent magnetization (SRM) due to the passage of a shock wave in the presence of an ambient magnetic field. In this study, we conducted pressure remanent magnetization (PRM) acquisition experiments on a variety of natural samples as an analog for SRM acquisition at pressures ranging up to 1.8 GPa. Comparison of the alternating field (AF) and thermal demagnetization behavior of PRM confirms that AF demagnetization is a more efficient method for removing SRM overprints than thermal demagnetization because SRM may persist to unblocking temperatures approaching the Curie temperatures of magnetic minerals. The blocking of SRM to high temperatures suggests that SRM could persist without being eradicated by viscous relaxation over geologic timescales. However, SRM has been rarely observed in natural samples likely because of two factors: (1) other forms of impact-related remanence (e.g., thermal remanent magnetization from impact-related heating or chemical remanent magnetization from postimpact hydrothermal activity) are often acquired by target rocks that overprint SRM, and (2) low SRM acquisition efficiencies may prevent SRM from being distinguished from the underlying primary remanence or other overprints due to its low magnetization intensity.

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Magnetic classification of stony meteorites: 2. Non‐ordinary chondrites

Cited by 76 publications

References 51 publications

Spectral reflectance properties of carbonaceous chondrites: 7. CK chondrites

Spectral reflectance properties of carbonaceous chondrites: 7. CK chondrites

Paleomagnetic Records of Meteorites and Early Planetesimal Differentiation

Preservation and detectability of shock‐induced magnetization

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