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Genesis of Fe–Ti Oxide-Bearing Ultramafic Intrusions in the Duluth Complex, Minnesota, USA.

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Title: Genesis of Fe–Ti Oxide-Bearing Ultramafic Intrusions in the Duluth Complex, Minnesota, USA.
Authors: Kleinsasser, Jackie M1 (AUTHOR) jmkleinsa@gmail.com, Simon, Adam C1 (AUTHOR), Peterson, Dean2 (AUTHOR), Kattemalavadi, Amartya1 (AUTHOR), Goan, Ian R1 (AUTHOR), Keller, Tobias3 (AUTHOR), Hudak, George J4 (AUTHOR), Koshurba, Kaitlin1 (AUTHOR)
Source: Journal of Petrology. May2024, Vol. 65 Issue 5, p1-25. 25p.
Subjects: Geochemical modeling, Genetic models, Pyroxenite, Ilmenite, Peridotite, Sulfide minerals
Geographic Terms: Duluth (Minn.), Minnesota
Abstract: The Duluth Complex is a large mafic intrusive system located in northeastern Minnesota emplaced as part of the 1.1-Ga Midcontinent Rift. Several Fe–Ti oxide-bearing ultramafic intrusions are hosted along the Western Margin of the Duluth Complex, and are discordant bodies present in a variety of geometries, hosted in multiple rock types, and dominated by peridotite, pyroxenite, and semi-massive to massive Fe–Ti oxide rock types. Their origin has been debated, and here we present geochemical evidence and modeling that supports a purely magmatic origin for the Titac and Longnose Fe–Ti oxide-bearing ultramafic intrusions. Ilmenite and titanomagnetite textures indicate a protracted cooling process, and δ34S values of sulfides reveal little assimilation of the footwall Virginia Formation, a fine-grained pelitic unit that contains sulfide-rich bands. We model the crystallization of a hypothetical parental magma composition to the host intrusion of Longnose using Rhyolite-MELTS and demonstrate that the accumulation of Fe–Ti oxides in the discordant intrusions cannot be explained by density-driven segregation of crystallized Fe–Ti oxides. Instead, we show that the development of silicate liquid immiscibility, occurring by the unmixing of the silicate melt into conjugate Si- and Fe-rich melts, can result in the effective segregation and transportation of the Fe-rich melt. The Fe-rich melt is ~2 orders of magnitude less viscous than the Si-rich melt, allowing the Fe-rich melt to be more effectively segregated and transported in the mush regime (crystallinities >50%). This suggests that viscosity, in addition to density, plays a significant role in forming the discordant Fe–Ti oxide-bearing ultramafic intrusions. We propose a genetic model that could also be responsible for the Fe–Ti oxide-rich layers or bands that are hosted within the igneous stratigraphy of mafic intrusions of the Duluth Complex. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Petrology is the property of Oxford University Press / USA 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
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DbLabel: Engineering Source
An: 177611625
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
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  Label: Title
  Group: Ti
  Data: Genesis of Fe–Ti Oxide-Bearing Ultramafic Intrusions in the Duluth Complex, Minnesota, USA.
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  Data: <searchLink fieldCode="AR" term="%22Kleinsasser%2C+Jackie+M%22">Kleinsasser, Jackie M</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> jmkleinsa@gmail.com</i><br /><searchLink fieldCode="AR" term="%22Simon%2C+Adam+C%22">Simon, Adam C</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Peterson%2C+Dean%22">Peterson, Dean</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kattemalavadi%2C+Amartya%22">Kattemalavadi, Amartya</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Goan%2C+Ian+R%22">Goan, Ian R</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Keller%2C+Tobias%22">Keller, Tobias</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Hudak%2C+George+J%22">Hudak, George J</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Koshurba%2C+Kaitlin%22">Koshurba, Kaitlin</searchLink><relatesTo>1</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Petrology%22">Journal of Petrology</searchLink>. May2024, Vol. 65 Issue 5, p1-25. 25p.
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  Data: <searchLink fieldCode="DE" term="%22Geochemical+modeling%22">Geochemical modeling</searchLink><br /><searchLink fieldCode="DE" term="%22Genetic+models%22">Genetic models</searchLink><br /><searchLink fieldCode="DE" term="%22Pyroxenite%22">Pyroxenite</searchLink><br /><searchLink fieldCode="DE" term="%22Ilmenite%22">Ilmenite</searchLink><br /><searchLink fieldCode="DE" term="%22Peridotite%22">Peridotite</searchLink><br /><searchLink fieldCode="DE" term="%22Sulfide+minerals%22">Sulfide minerals</searchLink>
– Name: SubjectGeographic
  Label: Geographic Terms
  Group: Su
  Data: <searchLink fieldCode="DE" term="%22Duluth+%28Minn%2E%29%22">Duluth (Minn.)</searchLink><br /><searchLink fieldCode="DE" term="%22Minnesota%22">Minnesota</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: The Duluth Complex is a large mafic intrusive system located in northeastern Minnesota emplaced as part of the 1.1-Ga Midcontinent Rift. Several Fe–Ti oxide-bearing ultramafic intrusions are hosted along the Western Margin of the Duluth Complex, and are discordant bodies present in a variety of geometries, hosted in multiple rock types, and dominated by peridotite, pyroxenite, and semi-massive to massive Fe–Ti oxide rock types. Their origin has been debated, and here we present geochemical evidence and modeling that supports a purely magmatic origin for the Titac and Longnose Fe–Ti oxide-bearing ultramafic intrusions. Ilmenite and titanomagnetite textures indicate a protracted cooling process, and δ34S values of sulfides reveal little assimilation of the footwall Virginia Formation, a fine-grained pelitic unit that contains sulfide-rich bands. We model the crystallization of a hypothetical parental magma composition to the host intrusion of Longnose using Rhyolite-MELTS and demonstrate that the accumulation of Fe–Ti oxides in the discordant intrusions cannot be explained by density-driven segregation of crystallized Fe–Ti oxides. Instead, we show that the development of silicate liquid immiscibility, occurring by the unmixing of the silicate melt into conjugate Si- and Fe-rich melts, can result in the effective segregation and transportation of the Fe-rich melt. The Fe-rich melt is ~2 orders of magnitude less viscous than the Si-rich melt, allowing the Fe-rich melt to be more effectively segregated and transported in the mush regime (crystallinities >50%). This suggests that viscosity, in addition to density, plays a significant role in forming the discordant Fe–Ti oxide-bearing ultramafic intrusions. We propose a genetic model that could also be responsible for the Fe–Ti oxide-rich layers or bands that are hosted within the igneous stratigraphy of mafic intrusions of the Duluth Complex. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Petrology is the property of Oxford University Press / USA 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=177611625
RecordInfo BibRecord:
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    Identifiers:
      – Type: doi
        Value: 10.1093/petrology/egae031
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 25
        StartPage: 1
    Subjects:
      – SubjectFull: Geochemical modeling
        Type: general
      – SubjectFull: Genetic models
        Type: general
      – SubjectFull: Pyroxenite
        Type: general
      – SubjectFull: Ilmenite
        Type: general
      – SubjectFull: Peridotite
        Type: general
      – SubjectFull: Sulfide minerals
        Type: general
      – SubjectFull: Duluth (Minn.)
        Type: general
      – SubjectFull: Minnesota
        Type: general
    Titles:
      – TitleFull: Genesis of Fe–Ti Oxide-Bearing Ultramafic Intrusions in the Duluth Complex, Minnesota, USA.
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            – D: 01
              M: 05
              Text: May2024
              Type: published
              Y: 2024
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