Devonian to Carboniferous collision in the Greenland Caledonides; U-Pb zircon and Sm-Nd ages of high-pressure and ultrahigh-pressure metamorphism

Jane A Gilotti; Allen P Nutman; Hannes K Brueckner

doi:10.1007/s00410-004-0600-4

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Devonian to Carboniferous collision in the Greenland Caledonides; U-Pb zircon and Sm-Nd ages of high-pressure and ultrahigh-pressure metamorphism

Journal article

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Devonian to Carboniferous collision in the Greenland Caledonides; U-Pb zircon and Sm-Nd ages of high-pressure and ultrahigh-pressure metamorphism

Jane A Gilotti, Allen P Nutman and Hannes K Brueckner

Contributions to mineralogy and petrology, Vol.148(2), pp.216-235

10/2004

DOI: 10.1007/s00410-004-0600-4

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Abstract

A variety of eclogites from an E-W transect across the N-E Greenland eclogite province have been studied to establish the timing of high P (HP) and ultrahigh-P (UHP) metamorphism in this N segment of the Laurentian margin. Results, combined with less precise Sm-Nd ages and earlier results, point to a Devonian age of HP metamorphism in the W and central portions of the eclogite province. An UHP kyanite eclogite from the E part of the transect contains equant metamorphic zircon with homogeneous to patchy zoning in CL and HP inclusions of garnet, omphacite and kyanite. These zircons have slightly higher U, Th and Th/U values than the HP ones, no Eu anomaly, and are thus comparable to UHP zircons in the literature. The (super 206) Pb/ (super 238) U age of these zircons is 360 + or - 5 Ma, much younger than the HP eclogites. The same sample gives a Sm-Nd age of 342 + or - 6 Ma. Unlike the HP eclogites, the Sm-Nd age of the UHP rock is approximately 20 Ma younger than the U-Pb zircon age and most likely records slow cooling through the closure T, since peak T were in excess of 900 degrees C. Widespread HP metamorphism of both the Laurentian and Baltica continental margins marks the culmination of this continent-continent collision in the Devonian. Carboniferous UHP conditions, though localized in the E, suggest a prolonged collisional history rather than a short-lived Scandian orogeny. The traditional Silurian Scandian orogeny should thus be extended through the Devonian.

absolute age

Arctic region

Baltica

Caledonides

Carboniferous

crust

dates

Devonian

eclogite

geochemistry

Geochronology

Greenland

high pressure

high-grade metamorphism

ICP mass spectra

Igneous and metamorphic petrology

inclusions

isotope ratios

isotopes

laser ablation

laser methods

Laurentia

magma contamination

mass spectra

metamorphic rocks

metamorphism

mineral assemblages

nesosilicates

orthosilicates

P-T conditions

paleogeography

Paleozoic

petrography

plate collision

plate tectonics

pressure

radioactive isotopes

silicates

Sm/Nd

spectra

tectonics

terranes

textures

thermal ionization mass spectra

U/Pb

ultrahigh pressure

zircon

zircon group

Details

Title: Subtitle: Devonian to Carboniferous collision in the Greenland Caledonides; U-Pb zircon and Sm-Nd ages of high-pressure and ultrahigh-pressure metamorphism
Creators: Jane A Gilotti - University of Iowa
Allen P Nutman - Australian National University
Hannes K Brueckner - Queens College, CUNY
Resource Type: Journal article
Publication Details: Contributions to mineralogy and petrology, Vol.148(2), pp.216-235
Publisher: Springer International
DOI: 10.1007/s00410-004-0600-4
ISSN: 0010-7999
eISSN: 1432-0967
Language: English
Date published: 10/2004
Academic Unit: Earth and Environmental Sciences
Record Identifier: 9984229308202771

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