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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 (183)W 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 (183)W 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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http://dx.doi.org/10.1073/pnas.1524980113 | DOI Listing |
Sci Adv
December 2021
Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA.
Chondrites display isotopic variations for moderately volatile elements, the origin of which is uncertain and could have involved evaporation/condensation processes in the protoplanetary disk, incomplete mixing of the products of stellar nucleosynthesis, or aqueous alteration on parent bodies. Here, we report high-precision K and Rb isotopic data of carbonaceous chondrites, providing new insights into the cause of these isotopic variations. We find that the K and Rb isotopic compositions of carbonaceous chondrites correlate with their abundance depletions, the fractions of matrix material, and previously measured Te and Zn isotopic compositions.
View Article and Find Full Text PDFWe measured noble gases in "cluster chondrite clasts" from nine unequilibrated ordinary chondrites (UOCs). For five meteorites, we also present data for so-called "clastic matrix," the impact-brecciated material in which the angular to subrounded cluster chondrite clasts are often embedded. Cluster chondrite clasts are characterized by close-fit texture of deformed and indented chondrules with lower amounts of fine-grained interchondrule matrix than in other UOCs (Metzler 2012).
View Article and Find Full Text PDFNat Astron
January 2020
Physics Department and McDonnell Center for the Space Sciences, Washington University, Saint Louis, MO 63130, USA.
Calcium aluminum rich inclusions (CAIs) are one of the first solids to have condensed in the solar nebula, while presolar grains formed in various evolved stellar environments. It is generally accepted that CAIs formed close to the Sun at temperatures above 1500 K, where presolar grains could not survive, and were then transported to other regions of the nebula where the accretion of planetesimals took place. In this context, a commonly held view is that presolar grains are found solely in the fine-grained rims surrounding chondrules and in the low-temperature fine-grained matrix that binds the various meteoritic components together.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2019
Laboratoire Domaines Océaniques UMR/CNRS 6538, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Technopôle Brest-Iroise, 29280 Plouzané, France.
Acta Geogr Geol Meteorol Debr Geol Gemorfol Termeszfoldr Sor
February 2019
'Vulcano' Petrology and Geochemistry Research Group, Department of Mineralogy Geochemistry and Petrology, Faculty of Science and Informatics, University of Szeged, Hungary,
We report on the mineralogy, petrography, and oxygen isotopic compositions of primary olivine and plagioclase/feldspathic mesostases in chondrules and of secondary magnetite and fayalite in chondrules and matrix of an oxidized Bali-like CV3.1 carbonaceous chondrite, Kaba. In this meteorite, compositionally nearly pure fayalite (Fa) associates with hedenbergite (FsWo), magnetite, and Fe,Ni-sulfides.
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