View in EDS

Crustal differentiation in the early solar system: Clues from the unique achondrite Northwest Africa 7325 (NWA 7325).

Saved in:
Bibliographic Details
Title: Crustal differentiation in the early solar system: Clues from the unique achondrite Northwest Africa 7325 (NWA 7325).
Authors: Barrat, J.A.1 barrat@univ-brest.fr, Greenwood, R.C.2, Verchovsky, A.B.2, Gillet, Ph.3, Bollinger, C.4, Langlade, J.A.4, Liorzou, C.1, Franchi, I.A.2
Source: Geochimica et Cosmochimica Acta. Nov2015, Vol. 168, p280-292. 13p.
Subjects: Achondrites, Pyroxene, Trace elements, Petrology, Milky Way
Abstract: The unique achondrite NWA 7325 is an unusual olivine gabbro composed chiefly of calcic plagioclase (An 85–93 ), diopsidic pyroxene (En 50.1–54.0 Wo 44.8–49.3 Fs 0.6–1 . 3 ), and forsteritic olivine (Fo 97 ). It is Al and Mg-rich and Fe and Na-poor and displays very low concentrations of incompatible trace elements, much below 0.3 × CI abundances for many of them. It is also characterized by huge Eu and Sr anomalies (Eu/Eu ∗ = 65, Sr n /Ce n = 240). Although the O isotopic composition of NWA 7325 and some ureilites (those with olivine cores in the range Fo 75 –Fo 88 ) are similar, a genetic relationship between them is unlikely due to the Fe-poor composition of NWA 7325. It is almost certainly derived from a distinct planetesimal, not previously sampled by other achondrites. The low Na/Al, Ga/Al, Zn/Al ratios as well as the low K, Rb and Cs shown by NWA 7325, suggest a volatile-depleted parent body. This unique gabbro is demonstrably a cumulate, but the composition of its parental melt cannot be precisely assessed. However, the liquid from which NWA 7325 crystallized would have been very poor in incompatible trace elements (Yb in the range of 0.25–1.5 × CI abundance) with a very large positive Eu anomaly. Such a melt cannot be the product of the early magmatic activity on a small parent body. Instead, we propose that the parental melt to NWA 7325 formed as a consequence of the total melting of an ancient gabbroic lithology, possibly upon impact, in agreement with the systematics of highly siderophile elements and 26 Al– 26 Mg. Based on recent dating, the crustal material that was parental to NWA 7325 must have been older than 4562.8 Ma, and formed possibly ≈4566 Ma ago. If this scenario is correct, NWA 7325 provides evidence of one of the earliest crusts on a differentiated body so far studied. [ABSTRACT FROM AUTHOR]
Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
FullText Text:
  Availability: 0
Header DbId: egs
DbLabel: Engineering Source
An: 109955776
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
IllustrationInfo
Items – Name: Title
  Label: Title
  Group: Ti
  Data: Crustal differentiation in the early solar system: Clues from the unique achondrite Northwest Africa 7325 (NWA 7325).
– Name: Author
  Label: Authors
  Group: Au
  Data: <searchLink fieldCode="AR" term="%22Barrat%2C+J%2EA%2E%22">Barrat, J.A.</searchLink><relatesTo>1</relatesTo><i> barrat@univ-brest.fr</i><br /><searchLink fieldCode="AR" term="%22Greenwood%2C+R%2EC%2E%22">Greenwood, R.C.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Verchovsky%2C+A%2EB%2E%22">Verchovsky, A.B.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Gillet%2C+Ph%2E%22">Gillet, Ph.</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Bollinger%2C+C%2E%22">Bollinger, C.</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Langlade%2C+J%2EA%2E%22">Langlade, J.A.</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Liorzou%2C+C%2E%22">Liorzou, C.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Franchi%2C+I%2EA%2E%22">Franchi, I.A.</searchLink><relatesTo>2</relatesTo>
– Name: TitleSource
  Label: Source
  Group: Src
  Data: <searchLink fieldCode="JN" term="%22Geochimica+et+Cosmochimica+Acta%22">Geochimica et Cosmochimica Acta</searchLink>. Nov2015, Vol. 168, p280-292. 13p.
– Name: Subject
  Label: Subjects
  Group: Su
  Data: <searchLink fieldCode="DE" term="%22Achondrites%22">Achondrites</searchLink><br /><searchLink fieldCode="DE" term="%22Pyroxene%22">Pyroxene</searchLink><br /><searchLink fieldCode="DE" term="%22Trace+elements%22">Trace elements</searchLink><br /><searchLink fieldCode="DE" term="%22Petrology%22">Petrology</searchLink><br /><searchLink fieldCode="DE" term="%22Milky+Way%22">Milky Way</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The unique achondrite NWA 7325 is an unusual olivine gabbro composed chiefly of calcic plagioclase (An 85–93 ), diopsidic pyroxene (En 50.1–54.0 Wo 44.8–49.3 Fs 0.6–1 . 3 ), and forsteritic olivine (Fo 97 ). It is Al and Mg-rich and Fe and Na-poor and displays very low concentrations of incompatible trace elements, much below 0.3 × CI abundances for many of them. It is also characterized by huge Eu and Sr anomalies (Eu/Eu ∗ = 65, Sr n /Ce n = 240). Although the O isotopic composition of NWA 7325 and some ureilites (those with olivine cores in the range Fo 75 –Fo 88 ) are similar, a genetic relationship between them is unlikely due to the Fe-poor composition of NWA 7325. It is almost certainly derived from a distinct planetesimal, not previously sampled by other achondrites. The low Na/Al, Ga/Al, Zn/Al ratios as well as the low K, Rb and Cs shown by NWA 7325, suggest a volatile-depleted parent body. This unique gabbro is demonstrably a cumulate, but the composition of its parental melt cannot be precisely assessed. However, the liquid from which NWA 7325 crystallized would have been very poor in incompatible trace elements (Yb in the range of 0.25–1.5 × CI abundance) with a very large positive Eu anomaly. Such a melt cannot be the product of the early magmatic activity on a small parent body. Instead, we propose that the parental melt to NWA 7325 formed as a consequence of the total melting of an ancient gabbroic lithology, possibly upon impact, in agreement with the systematics of highly siderophile elements and 26 Al– 26 Mg. Based on recent dating, the crustal material that was parental to NWA 7325 must have been older than 4562.8 Ma, and formed possibly ≈4566 Ma ago. If this scenario is correct, NWA 7325 provides evidence of one of the earliest crusts on a differentiated body so far studied. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=109955776
RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1016/j.gca.2015.07.020
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 13
        StartPage: 280
    Subjects:
      – SubjectFull: Achondrites
        Type: general
      – SubjectFull: Pyroxene
        Type: general
      – SubjectFull: Trace elements
        Type: general
      – SubjectFull: Petrology
        Type: general
      – SubjectFull: Milky Way
        Type: general
    Titles:
      – TitleFull: Crustal differentiation in the early solar system: Clues from the unique achondrite Northwest Africa 7325 (NWA 7325).
        Type: main
  BibRelationships:
    HasContributorRelationships:
      – PersonEntity:
          Name:
            NameFull: Barrat, J.A.
      – PersonEntity:
          Name:
            NameFull: Greenwood, R.C.
      – PersonEntity:
          Name:
            NameFull: Verchovsky, A.B.
      – PersonEntity:
          Name:
            NameFull: Gillet, Ph.
      – PersonEntity:
          Name:
            NameFull: Bollinger, C.
      – PersonEntity:
          Name:
            NameFull: Langlade, J.A.
      – PersonEntity:
          Name:
            NameFull: Liorzou, C.
      – PersonEntity:
          Name:
            NameFull: Franchi, I.A.
    IsPartOfRelationships:
      – BibEntity:
          Dates:
            – D: 01
              M: 11
              Text: Nov2015
              Type: published
              Y: 2015
          Identifiers:
            – Type: issn-print
              Value: 00167037
          Numbering:
            – Type: volume
              Value: 168
          Titles:
            – TitleFull: Geochimica et Cosmochimica Acta
              Type: main
ResultId 1