An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land
Liverpool Land, at the southern tip of the Greenland Caledonides, exposes a composite metamorphic terrane: the midcrustal granulite-facies Jaettedal Complex tectonically juxtaposed against the eclogite-facies, peridotite-bearing Tvaerdal Complex. The Jaettedal Complex is a Laurentian terrane, wherea...
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ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D84T6JK2 2023-05-15T16:28:28+02:00 An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land Brueckner, Hannes K. Medaris, Jr., L. G. Belousova, E. A. Johnston, S. M. Griffin, W. L. Hartz, E. H. Hemming, Sidney R. Ghent, E. Bubbico, R. 2016 https://doi.org/10.7916/D84T6JK2 English eng The University of Chicago Press https://doi.org/10.7916/D84T6JK2 Geochemistry Metamorphic rocks Eclogite Granulite articles 2016 ftcolumbiauniv https://doi.org/10.7916/D84T6JK2 2019-04-04T08:14:58Z Liverpool Land, at the southern tip of the Greenland Caledonides, exposes a composite metamorphic terrane: the midcrustal granulite-facies Jaettedal Complex tectonically juxtaposed against the eclogite-facies, peridotite-bearing Tvaerdal Complex. The Jaettedal Complex is a Laurentian terrane, whereas the Tvaerdal Complex was proposed by earlier investigators to be a Baltic terrane. PT estimates (8807–9207C at 35–40 kbar) and Sm-Nd mineral isochrons from Tvaerdal eclogites indicate that recrystallization occurred under ultrahigh-pressure (UHP) metamorphic conditions ≈400 m.yr. ago, the same time and under similar conditions as the Western Gneiss Complex of the Norwegian Caledonides. Detrital zircons from the Tvaerdal Complex, analyzed for U-Pb, Lu-Hf, and trace elements by laser ablation inductively coupled plasma mass spectrometry, give concordant Mesoproterozoic ages but not the Archean and ≈1.8 Ga Proterozoic ages characteristic of Laurentian terranes. Most remaining concordant U-Pb ages are 411–375Ma (i.e., Scandian), which contrast with older (≈460–410 Ma) zircon ages from the Jaettedal Complex as well as other Laurentian terranes. Both the Precambrian and the Scandian age sets confirm the Tvaerdal Complex as an orphaned Baltic terrane. The Jaettedal Complex underwent a lengthy Caledonian history as part of a continental arc system during the closure of Iapetus, whereas the Tvaerdal Complex was a fragment of the approaching Baltic passive margin. UHP metamorphism occurred when this margin subducted into the mantle beneath Laurentia. We propose that the Tvaerdal Complex separated from Baltica and rose through the hot mantle wedge to the base of the overriding Laurentian crust by diapirism, a process that may explain its abundant anatectic granitoid intrusions. Article in Journal/Newspaper Greenland Columbia University: Academic Commons Greenland Liverpool Land ENVELOPE(-22.200,-22.200,70.917,70.917) |
institution |
Open Polar |
collection |
Columbia University: Academic Commons |
op_collection_id |
ftcolumbiauniv |
language |
English |
topic |
Geochemistry Metamorphic rocks Eclogite Granulite |
spellingShingle |
Geochemistry Metamorphic rocks Eclogite Granulite Brueckner, Hannes K. Medaris, Jr., L. G. Belousova, E. A. Johnston, S. M. Griffin, W. L. Hartz, E. H. Hemming, Sidney R. Ghent, E. Bubbico, R. An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land |
topic_facet |
Geochemistry Metamorphic rocks Eclogite Granulite |
description |
Liverpool Land, at the southern tip of the Greenland Caledonides, exposes a composite metamorphic terrane: the midcrustal granulite-facies Jaettedal Complex tectonically juxtaposed against the eclogite-facies, peridotite-bearing Tvaerdal Complex. The Jaettedal Complex is a Laurentian terrane, whereas the Tvaerdal Complex was proposed by earlier investigators to be a Baltic terrane. PT estimates (8807–9207C at 35–40 kbar) and Sm-Nd mineral isochrons from Tvaerdal eclogites indicate that recrystallization occurred under ultrahigh-pressure (UHP) metamorphic conditions ≈400 m.yr. ago, the same time and under similar conditions as the Western Gneiss Complex of the Norwegian Caledonides. Detrital zircons from the Tvaerdal Complex, analyzed for U-Pb, Lu-Hf, and trace elements by laser ablation inductively coupled plasma mass spectrometry, give concordant Mesoproterozoic ages but not the Archean and ≈1.8 Ga Proterozoic ages characteristic of Laurentian terranes. Most remaining concordant U-Pb ages are 411–375Ma (i.e., Scandian), which contrast with older (≈460–410 Ma) zircon ages from the Jaettedal Complex as well as other Laurentian terranes. Both the Precambrian and the Scandian age sets confirm the Tvaerdal Complex as an orphaned Baltic terrane. The Jaettedal Complex underwent a lengthy Caledonian history as part of a continental arc system during the closure of Iapetus, whereas the Tvaerdal Complex was a fragment of the approaching Baltic passive margin. UHP metamorphism occurred when this margin subducted into the mantle beneath Laurentia. We propose that the Tvaerdal Complex separated from Baltica and rose through the hot mantle wedge to the base of the overriding Laurentian crust by diapirism, a process that may explain its abundant anatectic granitoid intrusions. |
format |
Article in Journal/Newspaper |
author |
Brueckner, Hannes K. Medaris, Jr., L. G. Belousova, E. A. Johnston, S. M. Griffin, W. L. Hartz, E. H. Hemming, Sidney R. Ghent, E. Bubbico, R. |
author_facet |
Brueckner, Hannes K. Medaris, Jr., L. G. Belousova, E. A. Johnston, S. M. Griffin, W. L. Hartz, E. H. Hemming, Sidney R. Ghent, E. Bubbico, R. |
author_sort |
Brueckner, Hannes K. |
title |
An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land |
title_short |
An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land |
title_full |
An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land |
title_fullStr |
An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land |
title_full_unstemmed |
An Orphaned Baltic Terrane in the Greenland Caledonides: A Sm-Nd and Detrital Zircon Study of a High-Pressure/Ultrahigh-Pressure Complex in Liverpool Land |
title_sort |
orphaned baltic terrane in the greenland caledonides: a sm-nd and detrital zircon study of a high-pressure/ultrahigh-pressure complex in liverpool land |
publisher |
The University of Chicago Press |
publishDate |
2016 |
url |
https://doi.org/10.7916/D84T6JK2 |
long_lat |
ENVELOPE(-22.200,-22.200,70.917,70.917) |
geographic |
Greenland Liverpool Land |
geographic_facet |
Greenland Liverpool Land |
genre |
Greenland |
genre_facet |
Greenland |
op_relation |
https://doi.org/10.7916/D84T6JK2 |
op_doi |
https://doi.org/10.7916/D84T6JK2 |
_version_ |
1766018117420449792 |