scholarly journals Meteorite evidence for partial differentiation and protracted accretion of planetesimals

2020 ◽  
Vol 6 (30) ◽  
pp. eaba1303
Author(s):  
Clara Maurel ◽  
James F. J. Bryson ◽  
Richard J. Lyons ◽  
Matthew R. Ball ◽  
Rajesh V. Chopdekar ◽  
...  
Keyword(s):  
Parent Body ◽  
Thermal Impact ◽  
Iron Meteorites ◽  
Planetary Body ◽  
Classification Schemes ◽  
Partial Differentiation ◽  
Internal Structures ◽  
Natural Outcome ◽  
Collisional Evolution

Modern meteorite classification schemes assume that no single planetary body could be source of both unmelted (chondritic) and melted (achondritic) meteorites. This dichotomy is a natural outcome of formation models assuming that planetesimal accretion occurred nearly instantaneously. However, it has recently been proposed that the accretion of many planetesimals lasted over ≳1 million years (Ma). This could have resulted in partially differentiated internal structures, with individual bodies containing iron cores, achondritic silicate mantles, and chondritic crusts. This proposal can be tested by searching for a meteorite group containing evidence for these three layers. We combine synchrotron paleomagnetic analyses with thermal, impact, and collisional evolution models to show that the parent body of the enigmatic IIE iron meteorites was such a partially differentiated planetesimal. This implies that some chondrites and achondrites simultaneously coexisted on the same planetesimal, indicating that accretion was protracted and that apparently undifferentiated asteroids may contain melted interiors.

scholarly journals 4. Parent Bodies of Iron Meteorites

1977 ◽  
Vol 39 ◽  
pp. 439-444
Author(s):  
E. R. D. Scott
Keyword(s):  
Mineralogical Composition ◽  
Parent Body ◽  
Iron Meteorites ◽  
Chemical And Mineralogical Composition

On the basis of their chemical and mineralogical composition, 420 iron meteorites have been classified into 12 different groups. Each group seems to have come from a separate parent body. The largest group, IIIAB, probably formed an asteroidal core in a body approximately 100 km in radius, which was largely destroyed by collision 630 My ago. Another 67 analyzed irons do not belong to these groups, and may represent samples from another 20 or more bodies.

scholarly journals Fe-Ni-P-S Melt Pockets in Elga IIE Iron Meteorite: Evidence for the Origin at High-Pressures Up to 20 GPa

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 616 ◽  
Author(s):  
Konstantin Litasov ◽  
Svetlana Teplyakova ◽  
Anton Shatskiy ◽  
Konstantin Kuper
Keyword(s):  
Experimental Data ◽  
Solid Solution ◽  
Important Implication ◽  
High Pressures ◽  
Bulk Composition ◽  
Parent Body ◽  
Iron Meteorite ◽  
Iron Meteorites ◽  
High Pressures And Temperatures ◽  
Melt Pockets

Here we report new data on high-pressure microstructures in Elga group IIE iron meteorites, made of solidified Fe-Ni-P-S melt pockets and microcrystalline aggregates, which could be formed only at high pressures and temperatures according to the experimental data. The bulk composition of the melt pockets and crystals correspond to the Fe3P-Fe3S solid solution with the closure of an immiscibility gap at pressures near 20 GPa in static experiments. Some other melt pockets fit with the Fe2S-Fe2P compositions, which could also correspond to high pressures and temperatures. The results suggest a late shock episode during the formation of the IIE iron parent body, which may be prior or due to the final disruption that caused the meteorite arrival to Earth. It also has an important implication to the shock features in other meteorites, such as ureilite.

Origin of Iron Meteorite Groups IAB and IIICD

1980 ◽  
Vol 35 (8) ◽  
pp. 781-795 ◽  
Author(s):  
John T. Wasson ◽  
John Willis ◽  
Chien M. Wai ◽  
Alfred Kracher
Keyword(s):  
Parent Body ◽  
Iron Meteorite ◽  
Iron Meteorites ◽  
Impact Melt ◽  
Equilibrium Crystallization ◽  
Ni Content ◽  
Oxide Phases ◽  
Host Metal ◽  
Impact Melts ◽  
The Impact

AbstractSeveral low-Ni iron meteorites previously assigned to group IAB are reclassified IIICD on the basis of lower Ge, Ga, W and Ir concentrations and higher As concentrations; the low-Ni extreme of IIICD is now 62 mg/g, that of IAB is 64 mg/g. The resulting fractionation patterns in the two groups are quite similar. It has long been established that, in contrast to the magmatic iron meteorite groups, IAB and IIICD did not form by fractional crystallization of a metallic magma. Other models have been proposed, but all have serious flaws. A new model is proposed involving the formation of each iron in small pools of impact melt on a parent body consisting of material similar to the chondritic inclusions found in some IAB and IIICD irons, but initially unequilibrated. These impact melts ranged in temperatures from ~ 1190 K to ~ 1350 K. The degree of equilibration between melt and unmelted solids ranged from minimal at the lowest temperature to moderate at the highest temperature. The lowest temperature melts were near the cotectic in the Fe-Ni-S system with Ni contents of ~ 12 atom %. Upon cooling, these precipitated metal having ~ 600 mg/g Ni by equilibrium crystallization. The Ni-rich melt resulted from the melting of Ni-rich sulfides and metal in the unequilibrated chondritic parent. Low-Ni irons formed in high temperature melts near the composition of the FeS-Fe eutectic or somewhat more metal rich. We suggest that the decreasing Ge, Ga and refractory abundances with increasing Ni concentration reflect the trapping of these elements in oxide phases in the unequilibrated chondritic material, and that very little entered the Ni-rich melt parental to the Oktibbeha County iron. The remaining elements tended to have element/Ni ratios in the melts that were more or less independent of temperature. The remarkable correlation between I-Xe age of the chondritic inclusions and Ni content of the host metal is explained by a detailed evolution of (mega)regolith in which these groups originated. The most Ni-rich melts could only be generated from an unequilibrated chondrite parent; as the continuing deposition of impact energy produced increasingly higher grades of metamorphism, the maximum Ni content of the impact melts (and their subsequently precipitated metal) gradually decreased.

Thermal history and origin of the IVB iron meteorites and their parent body

2010 ◽  
Vol 74 (15) ◽  
pp. 4493-4506 ◽  
Author(s):  
Jijin Yang ◽  
Joseph I. Goldstein ◽  
Joseph R. Michael ◽  
Paul G. Kotula ◽  
Edward R.D. Scott
Keyword(s):  
Thermal History ◽  
Parent Body ◽  
Iron Meteorites

Mn-Fe systematics in major planetary body reservoirs in the solar system and the positioning of the Angrite Parent Body: A crystal-chemical perspective

2017 ◽  
Vol 102 (8) ◽  
pp. 1759-1762 ◽  
Author(s):  
James J. Papike ◽  
Paul V. Burger ◽  
Aaron S. Bell ◽  
Charles K. Shearer
Keyword(s):  
Solar System ◽  
Parent Body ◽  
Crystal Chemical ◽  
Planetary Body

scholarly journals The Relationship of Meteoritic Parent Body Thermal Histories and Electromagnetic Heating by a Pre-Main Sequence T Tauri Sun

1971 ◽  
Vol 12 ◽  
pp. 239-245 ◽  
Author(s):  
C.P. Sonett
Keyword(s):  
Main Sequence ◽  
Solar Nebula ◽  
Parent Body ◽  
Convincing Evidence ◽  
Iron Meteorites ◽  
T Tauri ◽  
Diffusion Studies ◽  
Thermal Histories ◽  
Relationship Of ◽  
The Relationship

Convincing evidence exists that meteoritic matter was reheated shortly after the initial condensation of the solar nebula for those meteorites thought to be derived from parent bodies. This evidence takes the form of cooling rates carefully determined from diffusion studies of the migration rate of Ni across kamacite-taenite boundaries in iron meteorites (Fish, Goles, and Anders, 1960; Goldstein and Ogilvie, 1965; Goldstein and Short, 1967; Wood, 1964). The notion that the irons condensed directly from the solar nebula requires that these measurements and the existence of large Widmanstätten figures be explained as a condensation event. This seems rather unlikely and, in any event, requires a far more complex explanation than heating and melting in a parent body.

Stable isotope genealogy of meteorites

1988 ◽  
Vol 325 (1587) ◽  
pp. 525-533 ◽  
Keyword(s):  
Stable Isotope ◽  
Oxygen Isotopes ◽  
Light Element ◽  
Iron Meteorites ◽  
Classification Schemes ◽  
Isotopic Signatures ◽  
The Earth

One of the oldest problems in meteoritics is that of taxonomically grouping samples. In recent years the use of isotopes, particularly oxygen isotopes has proved very successful in this respect. Other light-element systematics potentially can perform the same function. For example, nitrogen in iron meteorites, and nitrogen and carbon in ureilites and SNC meteorites. These measurements will serve to extend and augment existing classification schemes and provide clues to the nature of meteorite parent bodies. They can also aid in the recognition of the isotopic signatures relating to inaccessible regions of the Earth.

Investigations of Cosmic-Ray-Produced Nuclides in Iron Meteorites: 5. More Data on the Nuclides of Potassium and Noble Gases, on Exposure Ages and Meteoroid Sizes

1983 ◽  
Vol 38 (2) ◽  
pp. 273-280 ◽  
Author(s):  
H. Voshage ◽  
H. Feldmann ◽  
O. Braun
Keyword(s):  
Noble Gases ◽  
Cosmic Ray ◽  
Parent Body ◽  
Critical Examination ◽  
Iron Meteorites ◽  
Abundance Patterns ◽  
New Information ◽  
Abundance Anomalies ◽  
Chemical Groups ◽  
Exposure Ages

Abstract The concentrations of the cosmic-ray-produced He-, Ne-, and Ar-nuclides in samples of 31 iron meteorites have been determined by mass spectrometry. Thereby, the number of samples analyzed in this laboratory has grown to 83. A critical examination of all these results was performed. The data of at least 52 samples prove to be useful to describe the "normal" abundance patterns of cosmogenic noble gases in iron meteorites; the description is accomplished by a new system of equations that correlate some properly selected abundance ratios with one another. The correlations serve as an instrument to recognize and diagnose certain abundance anomalies (3He-or 38Ar-deficiencies) which occur in about 25% of all samples analyzed. They allow to select those data which may unhesitatingly be applied in calculations concerning the irradiation histories of the respective meteorites. Another matter of concern for establishing these histories are the cosmic-ray-exposure ages. Mass spectrometric abundance analyses on meteoritic potassium have provided new data on the 41K/40K exposure ages of about 10 iron meteorites as well as on meteoroid sizes and sample depths. For two meteorites of the chemical group IIIAB, Joe Wright Mountains and Picacho, the age values obtained are 685 and 635 Ma, respectively. The results confirm our previous conclusion that the IIIAB-irons resided originally within a more or less contiguous partial volume (metallic core?) of their parent body and were ejected in consequence of a single impact event that happened about 670 Ma ago. Another motive for the present investigation was to measure the exposure ages for meteorites of the chemical groups IIICD and HIE. However, the new information obtained on their age distributions is still inadequate to answer some old questions concerning a possible relationship to the event that produced the IIIAB-meteoroids 670 Ma ago.

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