8. Genetic Relations among Meteorites and Planets

On the basis of 180/160 and 170/160 ratios, meteorites and planets can be grouped into at least nine categories, as follows (in order of increasing 1°0): (1) type L and LL ordinary chondrites; (2) type H ordinary chondrites, type HE irons, and CI carbonaceous chondrites; (3) the nakhlites and Shergotty; (4) the earth, moon, and enstatite chondrites and achondrites; (5) basaltic achondrites, hypersthene achondrites, mesosiderites, pallasites and type IRB irons; (6) the ureilites; (7) C2 carbonaceous chondrite matrix, Bencubbin, Weatherford, and Kakangari; (8) C3 carbonaceous chondrites; (9) pallasites Eagle Station and Itzawisis. Objects of one category cannot be derived by fractionation or differentiation from the source materials of any other category, but must represent samples of different regions of an i nhomogeneous solar nebula. The isotopic classification, together with major-element abundances, provides a powerful method for recognition of interrelationships of the various meteorites and their parent bodies.

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Discovery of fossil asteroidal ice in primitive meteorite Acfer 094

Science Advances ◽

10.1126/sciadv.aax5078 ◽

2019 ◽

Vol 5 (11) ◽

pp. eaax5078 ◽

Cited By ~ 1

Author(s):

Megumi Matsumoto ◽

Akira Tsuchiyama ◽

Aiko Nakato ◽

Junya Matsuno ◽

Akira Miyake ◽

...

Keyword(s):

Solar Nebula ◽

Carbonaceous Chondrite ◽

Parent Body ◽

Carbonaceous Chondrites ◽

X Ray ◽

Porous Texture ◽

Fine Grained ◽

X Ray Computed ◽

Source Materials ◽

Insight Into

Carbonaceous chondrites are meteorites believed to preserve our planet’s source materials, but the precise nature of these materials still remains uncertain. To uncover pristine planetary materials, we performed synchrotron radiation–based x-ray computed nanotomography of a primitive carbonaceous chondrite, Acfer 094, and found ultraporous lithology (UPL) widely distributed in a fine-grained matrix. UPLs are porous aggregates of amorphous and crystalline silicates, Fe─Ni sulfides, and organics. The porous texture must have been formed by removal of ice previously filling pore spaces, suggesting that UPLs represent fossils of primordial ice. The ice-bearing UPLs formed through sintering of fluffy icy dust aggregates around the H2O snow line in the solar nebula and were incorporated into the Acfer 094 parent body, providing new insight into asteroid formation by dust agglomeration.

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Tungsten isotopic constraints on the age and origin of chondrules

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1524980113 ◽

2016 ◽

Vol 113 (11) ◽

pp. 2886-2891 ◽

Cited By ~ 66

Author(s):

Gerrit Budde ◽

Thorsten Kleine ◽

Thomas S. Kruijer ◽

Christoph Burkhardt ◽

Knut Metzler

Keyword(s):

Planet Formation ◽

Solar Nebula ◽

Carbonaceous Chondrite ◽

Critical Role ◽

Parent Body ◽

Uneven Distribution ◽

Time Interval ◽

Ordinary Chondrites ◽

Chondrule Formation ◽

Isotopic Constraints

Chondrules may have played a critical role in the earliest stages of planet formation by mediating the accumulation of dust into planetesimals. However, the origin of chondrules and their significance for planetesimal accretion remain enigmatic. Here, we show that chondrules and matrix in the carbonaceous chondrite Allende have complementary 183W anomalies resulting from the uneven distribution of presolar, stellar-derived dust. These data refute an origin of chondrules in protoplanetary collisions and, instead, indicate that chondrules and matrix formed together from a common reservoir of solar nebula dust. Because bulk Allende exhibits no 183W anomaly, chondrules and matrix must have accreted rapidly to their parent body, implying that the majority of chondrules from a given chondrite group formed in a narrow time interval. Based on Hf-W chronometry on Allende chondrules and matrix, this event occurred ∼2 million years after formation of the first solids, about coeval to chondrule formation in ordinary chondrites.

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Mössbauer study of redox processes in the evolution of chondrites

Mineralogical Magazine ◽

10.1180/minmag.1994.058.390.14 ◽

1994 ◽

Vol 58 (390) ◽

pp. 151-158 ◽

Cited By ~ 4

Author(s):

T. V. Malysheva

Keyword(s):

Carbonaceous Chondrite ◽

Carbonaceous Chondrites ◽

Ordinary Chondrites ◽

Mössbauer Study ◽

Experimental Conditions ◽

Oxidation Reduction ◽

Reducing Conditions ◽

Temperature Boundary ◽

The Matrix ◽

Main Components

AbstractThe evolution of Fe-containing phases of carbonaceous chondrites heated under various oxidation-reduction conditions was investigated by means of Mössbauer spectroscopy. Heating of the lower petrological types of chondrites (CM2) released gases which initially produced oxidizing conditions (∼450°C) and then reducing conditions (> 700°C Phase transformation occurred rapidly (during 1–5 minutes) at all temperatures. During heating the Fe-bearing phyllosilicate phases in CM2-chondrite converted to Fe-bearing olivine, metallic iron and troilite (pentlandite). These phases resemble those of CO3, CV3 and EH-chondrites. Iron distribution resembling that of ordinary chondrites (some additional Fe2+ in pyroxene) was obtained only by heating a mixture of oxidized matter (CM2) with reduced matter (EH).A phase transition discovered at 1050°C is probably the temperature boundary between conditions of formation of the two main components of ordinary chondrites: matrix and chondrules. Chondrules of ordinary chondrites may be formed at temperatures > 1050°C while the matrix forms at temperatures < 1050°C For the carbonaceous chondrite Kainzas (CO3) these temperatures are approximately 1000°C and < 900°C The experimental conditions determined for the evolution of chondrites do not contradict the theoretical two-component model of Wood-Anders-Ringwood and may further its development.

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9. Relationship between the Composition of Solid Solar-System Matter and Distance from the Sun

International Astronomical Union Colloquium ◽

10.1017/s025292110007055x ◽

1977 ◽

Vol 39 ◽

pp. 551-559 ◽

Cited By ~ 1

Author(s):

J. T. Wasson

Keyword(s):

Oort Cloud ◽

Asteroid Belt ◽

Refractory Element ◽

The Sun ◽

Ordinary Chondrites ◽

Element Abundances ◽

Fine Grained ◽

The Earth ◽

Degree Of Oxidation ◽

Planetary Processes

The chondritic meteorites have “solar” compositions, indicating that they have avoided fractionation in planetary processes such as partial melting or fractional crystallization. Since chondrites contain solar proportions of volatiles having nebular condensation temperatures ≤500 K, it follows that agglomeration of grains and accretion to parent bodies occurred after the nebula had cooled to such low temperatures, and, that models calling for simultaneous condensation and accretion of high-temperature minerals such as Fe-Ni metal or ferromagnesian silicates are implausible.Two independent intergroup fractionations have been recognized in chondritic materials; refractory element abundances (e.g., the Ca/Si ratio) and degree of oxidation measured by the FeO/(FeO + MgO) ratio decrease through the chondrite sequence: carbonaceous-ordinary-IAB-E. Hiatus between groups result from incomplete sampling by the Earth of the original spectrum. A plausible speculation is that this sequence reflects formation at different nebular pressures and temperatures, the fine-grained, oxidized, volatile-rich carbonaceous chondrites forming at lower temperatures >5 AU from the Sun, and the reduced enstatite chrondrites forming at higher temperatures near the Sun. The high fall frequency of the three groups of ordinary chondrites suggests an origin in the asteroid belt. The degree of oxidation of the IAB chondrites appears to be slightly lower than that of the Earth, suggesting an origin near or slightly less than 1 AU from the Sun. The O-isotope compositions of chondrites are consistent with this picture.Asteroids tend to be light or dark, with a hiatus in properties between these two classes. This can be understood if the light materials are ordinary chondrites originally formed at 2.2-3.5 AU, whereas the dark materials originated at >5 AU, and were deposited in the asteroid belt during a later period as a result of a major increase in the influx of cometary materials through the inner sc1ar system associated with the generation of the Oort cloud of comets.

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Trace-element abundances in hibonites from the Murchison carbonaceous chondrite: Constraints on high-temperature processes in the solar nebula

Geochimica et Cosmochimica Acta ◽

10.1016/0016-7037(88)90151-2 ◽

1988 ◽

Vol 52 (12) ◽

pp. 2841-2854 ◽

Cited By ~ 63

Author(s):

T.R Ireland ◽

A.J Fahey ◽

E.K Zinner

Keyword(s):

High Temperature ◽

Trace Element ◽

Solar Nebula ◽

Carbonaceous Chondrite ◽

Element Abundances ◽

High Temperature Processes

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10. General Discussion

Transactions of the International Astronomical Union ◽

10.1017/s0251107x00028066 ◽

1960 ◽

Vol 10 ◽

pp. 677-679 ◽

Cited By ~ 1

Keyword(s):

Yield Curve ◽

Fission Products ◽

Heavy Elements ◽

Sikhote Alin ◽

Heavy Nuclei ◽

Fission Yield ◽

Element Abundances ◽

The Earth ◽

R Process ◽

Nova Outburst

1. p. SELINOV: Anomalous abundances of Te and Xe isotopes in meteorites and in the Earth permit us to draw some conclusions concerning the age of uranium and the processes of nucleogenesis. According to the estimate by Hoyle the amount of 254Cf disintegrated during a super-nova outburst is of the order of io29 g or io~4 of the stellar mass. According to the fission-yield curve the isotopes of Te comprise about 1 % of the mass of fission products. The abundances of Te 128-131 are anomalously high, due to the fission of heavy nuclei. The element abundances do not permit us to draw any conclusions about the r-process. The isotopes of Te and Xe with even mass numbers give evidence in favour of the r-process (anomalously high abundances). But the amount of Te in meteorites and in Earth is about 1000 times less than it should be if formed during the outburst. The Sikhote- Alin meteorite shows the same anomaly. We may conclude that the heavy elements of the solar system have been formed not in a single super-nova outburst, but as a result of mixing from the totality of outbursts. According to Hoyle, this gives a definite estimate for the age of uranium.

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A unique basaltic micrometeorite expands the inventory of solar system planetary crusts

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0900328106 ◽

2009 ◽

Vol 106 (17) ◽

pp. 6904-6909 ◽

Cited By ~ 32

Author(s):

Matthieu Gounelle ◽

Marc Chaussidon ◽

Alessandro Morbidelli ◽

Jean-Alix Barrat ◽

Cécile Engrand ◽

...

Keyword(s):

Solar System ◽

Mineral Chemistry ◽

Carbonaceous Chondrites ◽

Isotopic Data ◽

Solar System Formation ◽

Sample Return ◽

Dust Transport ◽

Element Abundances ◽

Transport Dynamics ◽

Sample Return Mission

Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission.

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