Insights into (U)HP metamorphism of the Western Gneiss Region, Norway: A high-spatial resolution and high-precision zircon study

Joel W. DesOrmeau; Stacia M. Gordon; Andrew R.C. Kylander-Clark; Bradley R. Hacker; Samuel A. Bowring; Blair Schoene; Kyle M. Samperton

doi:10.1016/j.chemgeo.2015.08.004

Insights into (U)HP metamorphism of the Western Gneiss Region, Norway: A high-spatial resolution and high-precision zircon study

Joel W. DesOrmeau, Stacia M. Gordon, Andrew R.C. Kylander-Clark, Bradley R. Hacker, Samuel A. Bowring, Blair Schoene, Kyle M. Samperton

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Abstract

Combining high-spatial resolution and high-precision geochronology and geochemistry of zircon provides constraints on the timing and duration of ultrahigh-pressure (UHP) metamorphism resulting from the collision of Baltica-Avalonia and Laurentia during the Scandian orogeny in the Western Gneiss Region of Norway. Zircons were extracted from a layered eclogite in the Saltaneset region (southern UHP domain) and from an eclogite in the Ulsteinvik region (central UHP domain). Zircons were first analyzed for U-Pb and trace element compositions by laser ablation split-stream (LASS) inductively coupled plasma mass spectrometry (ICP-MS), followed by analysis of those same zircons that yielded Scandian dates by integrated U-Pb isotope dilution-thermal ionization mass spectrometry and Trace Element Analysis (TIMS-TEA). LASS results from a garnet-quartz layer within the Saltaneset eclogite give Scandian dates of ca. 413-397. Ma, with subsequent ID-TIMS analyses ranging from 408.9 ± 0.4. Ma to 401.4 ± 0.2. Ma (2σ). An omphacite-rich layer from the same eclogite yields LASS dates of ca. 414-398. Ma and a single ID-TIMS date of 396.7 ± 1.4. Ma. In comparison, the Ulsteinvik eclogite LASS results give dates spanning ca. 413-397. Ma, whereas ID-TIMS analyses range from 409.6 ± 0.6. Ma to 401.3 ± 0.4. Ma. ID-TIMS zircon data from the eclogites reveals two age populations: 1) ca. 409-407. Ma and 2) ca. 402. Ma. Both in situ and solution trace element data show a distinct pattern for Scandian zircons, with strongly-depleted HREE and weakly-negative Eu anomalies (Eu/Eu*), whereas inherited zircon REE patterns are distinguished by steep HREE slopes and marked negative Eu/Eu*. When coupled with partition coefficients calculated for zircon and garnet, these REE patterns indicate that zircon (re)crystallized during eclogite-facies metamorphism at ca. 409-407. Ma and ca. 402. Ma at two widely separated UHP localities.

Original language	English (US)
Pages (from-to)	138-155
Number of pages	18
Journal	Chemical Geology
Volume	414
DOIs	https://doi.org/10.1016/j.chemgeo.2015.08.004
State	Published - Oct 30 2015

All Science Journal Classification (ASJC) codes

Geology
Geochemistry and Petrology

Keywords

Isotope dilution-thermal ionization mass spectrometry
Laser ablation split-stream
Norway
Ultrahigh-pressure metamorphism
Zircon

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10.1016/j.chemgeo.2015.08.004

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@article{dd648827cdbd42da99e2ffd562b3a8a5,

title = "Insights into (U)HP metamorphism of the Western Gneiss Region, Norway: A high-spatial resolution and high-precision zircon study",

abstract = "Combining high-spatial resolution and high-precision geochronology and geochemistry of zircon provides constraints on the timing and duration of ultrahigh-pressure (UHP) metamorphism resulting from the collision of Baltica-Avalonia and Laurentia during the Scandian orogeny in the Western Gneiss Region of Norway. Zircons were extracted from a layered eclogite in the Saltaneset region (southern UHP domain) and from an eclogite in the Ulsteinvik region (central UHP domain). Zircons were first analyzed for U-Pb and trace element compositions by laser ablation split-stream (LASS) inductively coupled plasma mass spectrometry (ICP-MS), followed by analysis of those same zircons that yielded Scandian dates by integrated U-Pb isotope dilution-thermal ionization mass spectrometry and Trace Element Analysis (TIMS-TEA). LASS results from a garnet-quartz layer within the Saltaneset eclogite give Scandian dates of ca. 413-397. Ma, with subsequent ID-TIMS analyses ranging from 408.9 ± 0.4. Ma to 401.4 ± 0.2. Ma (2σ). An omphacite-rich layer from the same eclogite yields LASS dates of ca. 414-398. Ma and a single ID-TIMS date of 396.7 ± 1.4. Ma. In comparison, the Ulsteinvik eclogite LASS results give dates spanning ca. 413-397. Ma, whereas ID-TIMS analyses range from 409.6 ± 0.6. Ma to 401.3 ± 0.4. Ma. ID-TIMS zircon data from the eclogites reveals two age populations: 1) ca. 409-407. Ma and 2) ca. 402. Ma. Both in situ and solution trace element data show a distinct pattern for Scandian zircons, with strongly-depleted HREE and weakly-negative Eu anomalies (Eu/Eu*), whereas inherited zircon REE patterns are distinguished by steep HREE slopes and marked negative Eu/Eu*. When coupled with partition coefficients calculated for zircon and garnet, these REE patterns indicate that zircon (re)crystallized during eclogite-facies metamorphism at ca. 409-407. Ma and ca. 402. Ma at two widely separated UHP localities.",

keywords = "Isotope dilution-thermal ionization mass spectrometry, Laser ablation split-stream, Norway, Ultrahigh-pressure metamorphism, Zircon",

author = "DesOrmeau, {Joel W.} and Gordon, {Stacia M.} and Kylander-Clark, {Andrew R.C.} and Hacker, {Bradley R.} and Bowring, {Samuel A.} and Blair Schoene and Samperton, {Kyle M.}",

note = "Funding Information: This work was supported by NSF Grants EAR-1019709 , EAR-1062187 (Gordon), and EAR-1219942 (Hacker). High-precision mass spectrometry at MIT is possible because of an Instrumentation and Facilities grant (EAR-0931839 to S.A.B.) and the collective sharing of knowledge by the EARTHTIME community. Thanks to Jahan Ramezani for providing assistance in the MIT Isotope Laboratory. Helpful reviews from F. Corfu and H. Brueckner greatly improved the manuscript. Publisher Copyright: {\textcopyright} 2015 Elsevier B.V.",

year = "2015",

month = oct,

day = "30",

doi = "10.1016/j.chemgeo.2015.08.004",

language = "English (US)",

volume = "414",

pages = "138--155",

journal = "Chemical Geology",

issn = "0009-2541",

publisher = "Elsevier",

}

TY - JOUR

T1 - Insights into (U)HP metamorphism of the Western Gneiss Region, Norway

T2 - A high-spatial resolution and high-precision zircon study

AU - DesOrmeau, Joel W.

AU - Gordon, Stacia M.

AU - Kylander-Clark, Andrew R.C.

AU - Hacker, Bradley R.

AU - Bowring, Samuel A.

AU - Schoene, Blair

AU - Samperton, Kyle M.

N1 - Funding Information: This work was supported by NSF Grants EAR-1019709 , EAR-1062187 (Gordon), and EAR-1219942 (Hacker). High-precision mass spectrometry at MIT is possible because of an Instrumentation and Facilities grant (EAR-0931839 to S.A.B.) and the collective sharing of knowledge by the EARTHTIME community. Thanks to Jahan Ramezani for providing assistance in the MIT Isotope Laboratory. Helpful reviews from F. Corfu and H. Brueckner greatly improved the manuscript. Publisher Copyright: © 2015 Elsevier B.V.

PY - 2015/10/30

Y1 - 2015/10/30

N2 - Combining high-spatial resolution and high-precision geochronology and geochemistry of zircon provides constraints on the timing and duration of ultrahigh-pressure (UHP) metamorphism resulting from the collision of Baltica-Avalonia and Laurentia during the Scandian orogeny in the Western Gneiss Region of Norway. Zircons were extracted from a layered eclogite in the Saltaneset region (southern UHP domain) and from an eclogite in the Ulsteinvik region (central UHP domain). Zircons were first analyzed for U-Pb and trace element compositions by laser ablation split-stream (LASS) inductively coupled plasma mass spectrometry (ICP-MS), followed by analysis of those same zircons that yielded Scandian dates by integrated U-Pb isotope dilution-thermal ionization mass spectrometry and Trace Element Analysis (TIMS-TEA). LASS results from a garnet-quartz layer within the Saltaneset eclogite give Scandian dates of ca. 413-397. Ma, with subsequent ID-TIMS analyses ranging from 408.9 ± 0.4. Ma to 401.4 ± 0.2. Ma (2σ). An omphacite-rich layer from the same eclogite yields LASS dates of ca. 414-398. Ma and a single ID-TIMS date of 396.7 ± 1.4. Ma. In comparison, the Ulsteinvik eclogite LASS results give dates spanning ca. 413-397. Ma, whereas ID-TIMS analyses range from 409.6 ± 0.6. Ma to 401.3 ± 0.4. Ma. ID-TIMS zircon data from the eclogites reveals two age populations: 1) ca. 409-407. Ma and 2) ca. 402. Ma. Both in situ and solution trace element data show a distinct pattern for Scandian zircons, with strongly-depleted HREE and weakly-negative Eu anomalies (Eu/Eu*), whereas inherited zircon REE patterns are distinguished by steep HREE slopes and marked negative Eu/Eu*. When coupled with partition coefficients calculated for zircon and garnet, these REE patterns indicate that zircon (re)crystallized during eclogite-facies metamorphism at ca. 409-407. Ma and ca. 402. Ma at two widely separated UHP localities.

AB - Combining high-spatial resolution and high-precision geochronology and geochemistry of zircon provides constraints on the timing and duration of ultrahigh-pressure (UHP) metamorphism resulting from the collision of Baltica-Avalonia and Laurentia during the Scandian orogeny in the Western Gneiss Region of Norway. Zircons were extracted from a layered eclogite in the Saltaneset region (southern UHP domain) and from an eclogite in the Ulsteinvik region (central UHP domain). Zircons were first analyzed for U-Pb and trace element compositions by laser ablation split-stream (LASS) inductively coupled plasma mass spectrometry (ICP-MS), followed by analysis of those same zircons that yielded Scandian dates by integrated U-Pb isotope dilution-thermal ionization mass spectrometry and Trace Element Analysis (TIMS-TEA). LASS results from a garnet-quartz layer within the Saltaneset eclogite give Scandian dates of ca. 413-397. Ma, with subsequent ID-TIMS analyses ranging from 408.9 ± 0.4. Ma to 401.4 ± 0.2. Ma (2σ). An omphacite-rich layer from the same eclogite yields LASS dates of ca. 414-398. Ma and a single ID-TIMS date of 396.7 ± 1.4. Ma. In comparison, the Ulsteinvik eclogite LASS results give dates spanning ca. 413-397. Ma, whereas ID-TIMS analyses range from 409.6 ± 0.6. Ma to 401.3 ± 0.4. Ma. ID-TIMS zircon data from the eclogites reveals two age populations: 1) ca. 409-407. Ma and 2) ca. 402. Ma. Both in situ and solution trace element data show a distinct pattern for Scandian zircons, with strongly-depleted HREE and weakly-negative Eu anomalies (Eu/Eu*), whereas inherited zircon REE patterns are distinguished by steep HREE slopes and marked negative Eu/Eu*. When coupled with partition coefficients calculated for zircon and garnet, these REE patterns indicate that zircon (re)crystallized during eclogite-facies metamorphism at ca. 409-407. Ma and ca. 402. Ma at two widely separated UHP localities.

KW - Isotope dilution-thermal ionization mass spectrometry

KW - Laser ablation split-stream

KW - Norway

KW - Ultrahigh-pressure metamorphism

KW - Zircon

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U2 - 10.1016/j.chemgeo.2015.08.004

DO - 10.1016/j.chemgeo.2015.08.004

M3 - Article

AN - SCOPUS:84943339759

SN - 0009-2541

VL - 414

SP - 138

EP - 155

JO - Chemical Geology

JF - Chemical Geology

ER -

Insights into (U)HP metamorphism of the Western Gneiss Region, Norway: A high-spatial resolution and high-precision zircon study

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All Science Journal Classification (ASJC) codes

Keywords

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