Main-group pallasites: Thermal history, relationship to IIIAB irons, and origin

Yang, Jijin; Goldstein, Joseph I.; Scott, E. R. D.

doi:10.1016/j.gca.2010.04.016

Cited by 109 publications

(202 citation statements)

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“…The experimental cooling rates were calculated using islands sizes of 147 ± 4 nm and 158 ± 6 nm for the Imilac and Esquel meteorites respectively (Extended Data Fig. 2) and the relationship between island size and cooling rate 14 .…”

Section: Planetary Cooling Model the Planetary Cooling Model Employsmentioning

confidence: 99%

See 1 more Smart Citation

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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Section: Planetary Cooling Model the Planetary Cooling Model Employsmentioning

confidence: 99%

“…6), calculated using the observed island sizes of 147±4 nm and 158±6 nm, respectively (Extended Data Fig. 2), and the empirical relationship between island size and cooling rate 14 . The Imilac and Esquel meteorites resided at depths of 38±2.5 km and 45±4 km, respectively.…”

mentioning

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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“…At the time of the publication of the paper by Bottke et al (2006), experimental data seemed to indicate that iron meteorites cooled over 100 Myr and therefore their parent bodies survived for that period of time (Chabot & Kaak 2006). However, in the past few years, new cooling rate data and radiometric ages have shown that the destruction of iron meteorites' parent bodies must have begun much earlier, perhaps as early as a few million years after the formation of CAIs (Blichert-Toft et al 2010;Yang et al 2010b;Scott et al 2011). This implies that the process of the delivery of planetesimals to the inner asteroid belt must occur during the first few million years after the formation of CAIs, and before the outer planet reaches 50 Earth-masses.…”

Section: Implications Of the Resultsmentioning

confidence: 99%

On the Effect of Giant Planets on the Scattering of Parent Bodies of Iron Meteorite From the Terrestrial Planet Region Into the Asteroid Belt: A Concept Study

Haghighipour

Scott

2012

ApJ

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In their model for the origin of the parent bodies of iron meteorites, Bottke et al. proposed differentiated planetesimals, formed in 1-2 AU during the first 1.5 Myr, as the parent bodies, and suggested that these objects and their fragments were scattered into the asteroid belt as a result of interactions with planetary embryos. Although viable, this model does not include the effect of a giant planet that might have existed or been growing in the outer regions. We present the results of a concept study where we have examined the effect of a planetary body in the orbit of Jupiter on the early scattering of planetesimals from the terrestrial region into the asteroid belt. We integrated the orbits of a large battery of planetesimals in a disk of planetary embryos and studied their evolutions for different values of the mass of the planet. Results indicate that when the mass of the planet is smaller than 10 M ⊕ , its effects on the interactions among planetesimals and planetary embryos are negligible. However, when the planet mass is between 10 and 50 M ⊕ , simulations point to a transitional regime with ∼50 M ⊕ being the value for which the perturbing effect of the planet can no longer be ignored. Simulations also show that further increase of the mass of the planet strongly reduces the efficiency of the scattering of planetesimals from the terrestrial planet region into the asteroid belt. We present the results of our simulations and discuss their possible implications for the time of giant planet formation.

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“…Poleg zna~ilnih razlik v hitrosti ohlajanja med kemijskimi skupinami so tudi znotraj posameznih skupin razponi v hitrosti ohlajanja precej veliki. Zelo veliki razponi so lahko posledica trkov velikih diferenciranih mati~nih teles z drugimi ve~jimi telesi, pri ~emer so prvotna mati~na telesa razpadla na ve~ manj{ih, ki so se razli~no hitro ohlajala (yanG et al, 2008;Goldstein et al, 2009;yanG et al, 2010). Na podlagi hitrosti ohlajanja posameznega meteorita je možno oceniti, v katerem delu jedra mati~nega telesa je le-ta nastal.…”

Section: Hitrost Ohlajanja Meteorita Javorjeunclassified

Two years of the Javorje meteorite investigations

Miler¹,

Gosar²

2012

Geologija

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Klju~ne besede: železov meteorit Javorje, srednji oktaedrit IIIAB, sEM/EDs analiza, mineralna in kemijska sestava, hitrost ohlajanja, Poljanska dolina, slovenijaKey words: iron meteorite Javorje, medium octahedrite IIIAB, sEM/EDs analysis, mineral and chemical composition, cooling rate, Poljane Valley, slovenia Izvle~ekMeteorit Javorje je železov meteorit, natan~neje srednji oktaedrit iz kemijske skupine železovih meteoritov z oznako IIIAB s 7,83-odstotno vsebnostjo niklja. Najden je bil novembra 2009 blizu Javorij v Poljanski dolini. s skoraj petimi kilogrami predstavlja najve~ji in najtežji meteorit, kar so jih doslej na{li na ozemlju slovenije. Namen ~lanka je predstaviti glavne zna~ilnosti meteorita Javorje tudi slovenski geolo{ki javnosti. V ~lanku so povzeti rezultati že objavljene raziskave tega meteorita, dodane pa so nekatere novej{e ugotovitve in podrobnosti o glavnih, akcesornih in sekundarnih mineralih ter o hitrosti ohlajanja. AbstractMeteorite Javorje is a IIIAB medium octahedrite iron meteorite with 7.83 wt% Ni content. It was found in November 2009 near village Javorje in the Poljane Valley. With nearly five kilograms it represents the largest and heaviest meteorite found so far in the territory of slovenia. The purpose of this paper is to present general characteristics of meteorite Javorje to the slovenian geological community. This paper reviews results of already published research of this meteorite and provides some newer findings and details about major, accessory and secondary minerals, and also its cooling rate. UvodMeteorit Javorje je s skoraj petimi kilogrami najve~ji in najtežji meteorit izmed doslej najdenih na ozemlju slovenije, in prav je, da o izsledkih raziskav tega zanimivega predmeta seznanjamo tudi bralce Geologije, osrednje slovenske geolo{ke znanstvene revije. Pred dobrima dvema letoma je v bližini Javorij nad Poljansko dolino, zahodno od Škofje Loke, Vladimir Štibelj povsem po naklju~ju odkril meteorit, ki poleg železovega meteorita Av~e in kamnitega meteorita Jesenice, predstavlja tretji meteorit najden na ozemlju slovenije. Pri gradnji gozdne ceste je pozornost najditelja v novo skopanem cestnem useku na globini 65-70 cm pritegnila nenavadna gmota, ki se je po svojem videzu razlikovala od kamnine in tal v kateri je ležala. Ko jo je vzel v roke, je ugotovil, da je nenavadno težka. V trenutku je bil prepri~an, da je na{el izjemno najdbo in domneval, da je najdeni predmet meteorit. Domnevni meteorit je skrbno shranil ter o najdbi obvestil v Poljanski dolini dobro znanega geologa, nekdanjega sodelavca rudnika urana Žirovski vrh, Pavla A. Florjan~i~a. skupaj sta ugotovila, da je kos kovinski in da mo~no privla~i magnet. seveda pa tudi Pavle A. Florjan~i~ ni mogel brez analiz potrditi, da je najdba res meteorit. Zato sta za pomo~ prosila raziskovalce Geolo{kega zavoda slovenije. raziskave domnevnega meteorita so nam predstavljale velik raziskovalni izziv, saj se do takrat z materialom iz vesolja {e nismo sre~ali. Ko so preliminarne analize z vrsti~nim elektronskim mikroskopom v ...

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Main-group pallasites: Thermal history, relationship to IIIAB irons, and origin

Cited by 109 publications

References 50 publications

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

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

On the Effect of Giant Planets on the Scattering of Parent Bodies of Iron Meteorite From the Terrestrial Planet Region Into the Asteroid Belt: A Concept Study

Two years of the Javorje meteorite investigations

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