Chondrites as samples of differentiated planetesimals

Linda Elkins-Tanton, Benjamin P. Weiss, Maria T. Zuber

Research output: Contribution to journalArticle

144 Citations (Scopus)

Abstract

Chondritic meteorites are unmelted and variably metamorphosed aggregates of the earliest solids of the solar system. The variety of metamorphic textures in chondrites motivated the "onion shell" model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. Allende and a few other chondrites possess a unidirectional magnetization that can be best explained by a core dynamo on their parent body, indicating internal melting and differentiation. Here we show that a parent body that accreted to >~200km in radius by ~1.5Ma after the formation of calcium-aluminum-rich inclusions (CAIs) would have a differentiated interior, and ongoing accretion would add a solid undifferentiated crust overlying a differentiated interior, consistent with formational and evolutionary constraints inferred for the CV parent body. This body could have produced a magnetic field lasting more than 10Ma. This hypothesis represents a new model for the origin of some chondrites, presenting them as the unprocessed crusts of internally differentiated early planetesimals. Such bodies may exist in the asteroid belt today; the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, can be consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice-silicate mantles, covered with undifferentiated crusts.

Original languageEnglish (US)
Pages (from-to)1-10
Number of pages10
JournalEarth and Planetary Science Letters
Volume305
Issue number1-2
DOIs
StatePublished - May 1 2011
Externally publishedYes

Fingerprint

Silicates
Asteroids
protoplanets
planetesimal
chondrites
parent body
chondrite
Meteorites
Solar system
Ice
crust
Aluminum
Radioisotopes
asteroid
Magnetization
crusts
Melting
Iron
silicate
Textures

Keywords

  • Allende
  • Chondrite
  • Differentiation
  • Magma ocean
  • Planetesimal

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Chondrites as samples of differentiated planetesimals. / Elkins-Tanton, Linda; Weiss, Benjamin P.; Zuber, Maria T.

In: Earth and Planetary Science Letters, Vol. 305, No. 1-2, 01.05.2011, p. 1-10.

Research output: Contribution to journalArticle

Elkins-Tanton, Linda ; Weiss, Benjamin P. ; Zuber, Maria T. / Chondrites as samples of differentiated planetesimals. In: Earth and Planetary Science Letters. 2011 ; Vol. 305, No. 1-2. pp. 1-10.
@article{4d6ae3c1af6e406293f6fb40bdb76023,
title = "Chondrites as samples of differentiated planetesimals",
abstract = "Chondritic meteorites are unmelted and variably metamorphosed aggregates of the earliest solids of the solar system. The variety of metamorphic textures in chondrites motivated the {"}onion shell{"} model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. Allende and a few other chondrites possess a unidirectional magnetization that can be best explained by a core dynamo on their parent body, indicating internal melting and differentiation. Here we show that a parent body that accreted to >~200km in radius by ~1.5Ma after the formation of calcium-aluminum-rich inclusions (CAIs) would have a differentiated interior, and ongoing accretion would add a solid undifferentiated crust overlying a differentiated interior, consistent with formational and evolutionary constraints inferred for the CV parent body. This body could have produced a magnetic field lasting more than 10Ma. This hypothesis represents a new model for the origin of some chondrites, presenting them as the unprocessed crusts of internally differentiated early planetesimals. Such bodies may exist in the asteroid belt today; the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, can be consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice-silicate mantles, covered with undifferentiated crusts.",
keywords = "Allende, Chondrite, Differentiation, Magma ocean, Planetesimal",
author = "Linda Elkins-Tanton and Weiss, {Benjamin P.} and Zuber, {Maria T.}",
year = "2011",
month = "5",
day = "1",
doi = "10.1016/j.epsl.2011.03.010",
language = "English (US)",
volume = "305",
pages = "1--10",
journal = "Earth and Planetary Sciences Letters",
issn = "0012-821X",
publisher = "Elsevier",
number = "1-2",

}

TY - JOUR

T1 - Chondrites as samples of differentiated planetesimals

AU - Elkins-Tanton, Linda

AU - Weiss, Benjamin P.

AU - Zuber, Maria T.

PY - 2011/5/1

Y1 - 2011/5/1

N2 - Chondritic meteorites are unmelted and variably metamorphosed aggregates of the earliest solids of the solar system. The variety of metamorphic textures in chondrites motivated the "onion shell" model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. Allende and a few other chondrites possess a unidirectional magnetization that can be best explained by a core dynamo on their parent body, indicating internal melting and differentiation. Here we show that a parent body that accreted to >~200km in radius by ~1.5Ma after the formation of calcium-aluminum-rich inclusions (CAIs) would have a differentiated interior, and ongoing accretion would add a solid undifferentiated crust overlying a differentiated interior, consistent with formational and evolutionary constraints inferred for the CV parent body. This body could have produced a magnetic field lasting more than 10Ma. This hypothesis represents a new model for the origin of some chondrites, presenting them as the unprocessed crusts of internally differentiated early planetesimals. Such bodies may exist in the asteroid belt today; the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, can be consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice-silicate mantles, covered with undifferentiated crusts.

AB - Chondritic meteorites are unmelted and variably metamorphosed aggregates of the earliest solids of the solar system. The variety of metamorphic textures in chondrites motivated the "onion shell" model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. Allende and a few other chondrites possess a unidirectional magnetization that can be best explained by a core dynamo on their parent body, indicating internal melting and differentiation. Here we show that a parent body that accreted to >~200km in radius by ~1.5Ma after the formation of calcium-aluminum-rich inclusions (CAIs) would have a differentiated interior, and ongoing accretion would add a solid undifferentiated crust overlying a differentiated interior, consistent with formational and evolutionary constraints inferred for the CV parent body. This body could have produced a magnetic field lasting more than 10Ma. This hypothesis represents a new model for the origin of some chondrites, presenting them as the unprocessed crusts of internally differentiated early planetesimals. Such bodies may exist in the asteroid belt today; the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, can be consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice-silicate mantles, covered with undifferentiated crusts.

KW - Allende

KW - Chondrite

KW - Differentiation

KW - Magma ocean

KW - Planetesimal

UR - http://www.scopus.com/inward/record.url?scp=79953737331&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79953737331&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2011.03.010

DO - 10.1016/j.epsl.2011.03.010

M3 - Article

AN - SCOPUS:79953737331

VL - 305

SP - 1

EP - 10

JO - Earth and Planetary Sciences Letters

JF - Earth and Planetary Sciences Letters

SN - 0012-821X

IS - 1-2

ER -