scholarly journals Tungsten isotopic constraints on the age and origin of chondrules

2016 ◽  
Vol 113 (11) ◽  
pp. 2886-2891 ◽  
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.

Machiite, Al2Ti3O9, a new oxide mineral from the Murchison carbonaceous chondrite: A new ultra-refractory phase from the solar nebula

2020 ◽  
Vol 105 (2) ◽  
pp. 239-243 ◽  
Author(s):  
Alexander N. Krot ◽  
Kazuhide Nagashima ◽  
George R. Rossman
Keyword(s):  
Isotopic Composition ◽  
Solar Nebula ◽  
Carbonaceous Chondrite ◽  
Parent Body ◽  
Oxygen Isotopic Composition ◽  
New Mineral ◽  
Calculated Density ◽  
California Institute Of Technology ◽  
Oxygen Isotopic ◽  
Institute Of Technology

Abstract Machiite (IMA 2016-067), Al2Ti3O9, is a new mineral that occurs as a single euhedral crystal, 4.4 μm in size, in contact with an euhedral corundum grain, 12 μm in size, in a matrix of the Murchison CM2 carbonaceous chondrite. The mean chemical composition of holotype machiite by electron probe microanalysis is (wt%) TiO2 59.75, Al2O3 15.97, Sc2O3 10.29, ZrO2 9.18, Y2O3 2.86, FeO 1.09, CaO 0.44, SiO2 0.20, MgO 0.10, total 99.87, giving rise to an empirical formula (based on 9 oxygen atoms pfu) of (Al1.17Sc0.56Y0.10Ti0.084+Fe0.06Ca0.03Mg0.01)(Ti2.714+Zr0.28Si0.01)O9. The general formula is (Al,Sc)2(Ti4+,Zr)3O9. The end-member formula is Al2Ti3O9. Machiite has the C2/c schreyerite-type structure with a = 17.10 Å, b = 5.03 Å, c = 7.06 Å, β = 107°, V = 581 Å3, and Z = 4, as revealed by electron backscatter diffraction. The calculated density using the measured composition is 4.27 g/cm3. The machiite crystal is highly 16O-depleted relative to the coexisting corundum grain (Δ17O = –0.2 ± 2.4‰ and –24.1 ± 2.6‰, respectively; where Δ17O = δ17O – 0.52 × δ18O). Machiite is a new member of the schreyerite (V2Ti3O9) group and a new Sc,Zr-rich ultrarefractory phase formed in the solar nebula, either by gas-solid condensation or as a result of crystallization from a Ca,Al-rich melt having solar-like oxygen isotopic composition (Δ17O~ –25‰) under high-temperature (~1400–1500 °C) and low-pressure (~10-4–10-5 bar) conditions in the CAI-forming region near the protosun. The currently observed disequilibrium oxygen isotopic composition between machiite and corundum may indicate that machiite subsequently experienced oxygen isotopic exchange with a planetary-like 16O-poor gaseous reservoir either in the solar nebula or on the CM chondrite parent body. The name machiite is in honor of Chi Ma, mineralogist at California Institute of Technology, for his contributions to meteorite mineralogy and discovery of many new minerals representing extreme conditions of formation.

26Al records in chondrules from unequilibrated ordinary chondrites: II. Duration of chondrule formation and parent body thermal metamorphism

2008 ◽  
Vol 274 (1-2) ◽  
pp. 93-102 ◽  
Author(s):  
N.G. Rudraswami ◽  
J.N. Goswami ◽  
B. Chattopadhyay ◽  
S.K. Sengupta ◽  
A.P. Thapliyal
Keyword(s):  
Parent Body ◽  
Ordinary Chondrites ◽  
Thermal Metamorphism ◽  
Chondrule Formation

scholarly journals Meteors and Meteorite Falls in Morocco

2013 ◽  
Vol 17 ◽  
pp. 28-35 ◽  
Author(s):  
Abderrahmane Ibhi
Keyword(s):  
Recovery Rate ◽  
Carbonaceous Chondrite ◽  
Time Interval ◽  
Ordinary Chondrites ◽  
The Past ◽  
Meteorite Fall ◽  
Fall Recovery

During the last eighty years, thirteen meteorite falls were recorded in Morocco, which ten are well documented and named Douar Mghila, Oued el Hadjar, Itqiy, Zag, Bensour, Oum Dreyga, Benguerir, Tamdakht, Tissint and Aoussred. It represent only 0.011% of the Moroccan declared meteorites.The authenticated observed falls represent three types of different meteorites, eight ordinary chondrites (Four of type LL, three of type H and one of type EH), one carbonaceous chondrite and one Shergottite basaltic achondrites. The Morocco meteorite fall recovery rate, during the past eighty years, is low 0.11 falls per year on average per 2.11 km2 (or approximately one fall recovery per 10 year time interval).

scholarly journals Short time interval for condensation of high-temperature silicates in the solar accretion disk

2015 ◽  
Vol 112 (5) ◽  
pp. 1298-1303 ◽  
Author(s):  
Tu-Han Luu ◽  
Edward D. Young ◽  
Matthieu Gounelle ◽  
Marc Chaussidon
Keyword(s):  
Solar System ◽  
High Precision ◽  
Formation Mechanisms ◽  
Time Interval ◽  
Condensation Temperature ◽  
Short Time Interval ◽  
Ordinary Chondrites ◽  
Condensation Zone ◽  
Chondrule Formation ◽  
Short Time

Chondritic meteorites are made of primitive components that record the first steps of formation of solids in our Solar System. Chondrules are the major component of chondrites, yet little is known about their formation mechanisms and history within the solar protoplanetary disk (SPD). We use the reconstructed concentrations of short-lived 26Al in chondrules to constrain the timing of formation of their precursors in the SPD. High-precision bulk magnesium isotopic measurements of 14 chondrules from the Allende chondrite define a 26Al isochron with 26Al/27Al = 1.2(±0.2) × 10−5 for this subset of Allende chondrules. This can be considered to be the minimum bulk chondrule 26Al isochron because all chondrules analyzed so far with high precision (∼50 chondrules from CV and ordinary chondrites) have an inferred minimum bulk initial (26Al/27Al) ≥ 1.2 × 10−5. In addition, mineral 26Al isochrons determined on the same chondrules show that their formation (i.e., fusion of their precursors by energetic events) took place from 0 Myr to ∼2 Myr after the formation of their precursors, thus showing in some cases a clear decoupling in time between the two events. The finding of a minimum bulk chondrule 26Al isochron is used to constrain the astrophysical settings for chondrule formation. Either the temperature of the condensation zone dropped below the condensation temperature of chondrule precursors at ∼1.5 My after the start of the Solar System or the transport of precursors from the condensation zone to potential storage sites stopped after 1.5 My, possibly due to a drop in the disk accretion rate.

scholarly journals Discovery of fossil asteroidal ice in primitive meteorite Acfer 094

2019 ◽  
Vol 5 (11) ◽  
pp. eaax5078 ◽  
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.

scholarly journals 8. Genetic Relations among Meteorites and Planets

1977 ◽  
Vol 39 ◽  
pp. 545-550 ◽  
Author(s):  
R. N. Clayton
Keyword(s):  
Solar Nebula ◽  
Major Element ◽  
Carbonaceous Chondrite ◽  
Carbonaceous Chondrites ◽  
Powerful Method ◽  
Ordinary Chondrites ◽  
Element Abundances ◽  
The Earth ◽  
Enstatite Chondrites ◽  
Source Materials

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.

scholarly journals Solar nebula magnetic fields recorded in the Semarkona meteorite

Science ◽  
2014 ◽  
Vol 346 (6213) ◽  
pp. 1089-1092 ◽  
Author(s):  
Roger R. Fu ◽  
Benjamin P. Weiss ◽  
Eduardo A. Lima ◽  
Richard J. Harrison ◽  
Xue-Ning Bai ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Solar Nebula ◽  
Critical Role ◽  
Protoplanetary Disks ◽  
Terrestrial Planet ◽  
Central Star ◽  
Planetary Formation ◽  
Angular Momentum Transport ◽  
Disk Material ◽  
Chondrule Formation

Magnetic fields are proposed to have played a critical role in some of the most enigmatic processes of planetary formation by mediating the rapid accretion of disk material onto the central star and the formation of the first solids. However, there have been no experimental constraints on the intensity of these fields. Here we show that dusty olivine-bearing chondrules from the Semarkona meteorite were magnetized in a nebular field of 54 ± 21 microteslas. This intensity supports chondrule formation by nebular shocks or planetesimal collisions rather than by electric currents, the x-wind, or other mechanisms near the Sun. This implies that background magnetic fields in the terrestrial planet-forming region were likely 5 to 54 microteslas, which is sufficient to account for measured rates of mass and angular momentum transport in protoplanetary disks.

scholarly journals Machine learning applied to simulations of collisions between rotating, differentiated planets

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Miles L. Timpe ◽  
Maria Han Veiga ◽  
Mischa Knabenhans ◽  
Joachim Stadel ◽  
Stefano Marelli
Keyword(s):  
Machine Learning ◽  
Planet Formation ◽  
Critical Role ◽  
Ensemble Methods ◽  
Terrestrial Planet ◽  
Data Driven ◽  
Analytic Methods ◽  
Accurate Treatment ◽  
Post Impact ◽  
The Cost

AbstractIn the late stages of terrestrial planet formation, pairwise collisions between planetary-sized bodies act as the fundamental agent of planet growth. These collisions can lead to either growth or disruption of the bodies involved and are largely responsible for shaping the final characteristics of the planets. Despite their critical role in planet formation, an accurate treatment of collisions has yet to be realized. While semi-analytic methods have been proposed, they remain limited to a narrow set of post-impact properties and have only achieved relatively low accuracies. However, the rise of machine learning and access to increased computing power have enabled novel data-driven approaches. In this work, we show that data-driven emulation techniques are capable of classifying and predicting the outcome of collisions with high accuracy and are generalizable to any quantifiable post-impact quantity. In particular, we focus on the dataset requirements, training pipeline, and classification and regression performance for four distinct data-driven techniques from machine learning (ensemble methods and neural networks) and uncertainty quantification (Gaussian processes and polynomial chaos expansion). We compare these methods to existing analytic and semi-analytic methods. Such data-driven emulators are poised to replace the methods currently used in N-body simulations, while avoiding the cost of direct simulation. This work is based on a new set of 14,856 SPH simulations of pairwise collisions between rotating, differentiated bodies at all possible mutual orientations.

scholarly journals Accretion of a large LL parent planetesimal from a recently formed chondrule population

2020 ◽  
Vol 6 (16) ◽  
pp. eaay8641
Author(s):  
Graham H. Edwards ◽  
Terrence Blackburn
Keyword(s):  
Body Size ◽  
Size Distribution ◽  
Total Duration ◽  
Parent Body ◽  
Ordinary Chondrite ◽  
Minimum Size ◽  
Thermal Models ◽  
Early Stages ◽  
Chondritic Meteorites ◽  
Chondrule Formation

Chondritic meteorites, derived from asteroidal parent bodies and composed of millimeter-sized chondrules, record the early stages of planetary assembly. Yet, the initial planetesimal size distribution and the duration of delay, if any, between chondrule formation and chondrite parent body accretion remain disputed. We use Pb-phosphate thermochronology with planetesimal-scale thermal models to constrain the minimum size of the LL ordinary chondrite parent body and its initial allotment of heat-producing 26Al. Bulk phosphate 207Pb/206Pb dates of LL chondrites record a total duration of cooling ≥75 Ma, with an isothermal interior that cools over ≥30 Ma. Since the duration of conductive cooling scales with parent body size, these data require a ≥150-km radius parent body and a range of bulk initial 26Al/27Al consistent with the initial 26Al/27Al ratios of constituent LL chondrules. The concordance suggests that rapid accretion of a large LL parent asteroid occurred shortly after a major chondrule-forming episode.

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