Journal article
Caledonian eclogite-facies metamorphism of early Proterozoic protoliths from the North-East Greenland eclogite province
Contributions to mineralogy and petrology, Vol.130(2), pp.103-120
01/1998
DOI: 10.1007/s004100050353
Abstract
High-P metamorphic assemblages occur in mafic, ultramafic and a few intermediate rocks in a 400 X 100 km gneiss complex in NE Greenland. Geothermobarometry yielded T estimates of 700-800 degrees C and P estimates of > or = 1.5 GPa for an eclogite sensu stricto and as high as 2.35 GPa for a garnet websterite. The eclogite defines a garnet-clinopyroxene-amphibole-whole-rock Sm-Nd isochron of 405 + or - 24 m.y. Isofacial garnet websterites define garnet-clinopyroxene-orthopyroxene-amphibole-whole-rock (biotite) ages of 439 + or - 8 for a coarse-grained sample and 370 + or - 12 m.y. for a finer-grained variety. Overgrowths on zircons from the fine-grained pyroxenite and the eclogite give a pooled (super 206) Pb/ (super 238) U SHRIMP age of 377 + or - 7 m.y. Significantly younger Rb-Sr biotite ages of 357 + or - 8, 330 + or - 6 and 326 + or - 6 m.y. agree with young Rb-Sr, K-Ar and (super 40) Ar/ (super 39) Ar mineral ages from the gneiss complex and indicate slow cooling of the eclogitic rocks. Sm-Nd whole-rock model ages indicate that the eclogite protoliths are early Proterozoic in age, and (super 207) Pb/ (super 206) Pb SHRIMP ages of 1889 + or - 18 and 1981 + or - 8 for anhedral zircon cores probably reflect Proterozoic metasomatism. The epsilon (sub Nd) value (-5 to -16) and elevated (super 87) Sr/ (super 86) Sr ratios (0.708-0.715) confirm that the eclogite protoliths were an integral part of the continental crust long before Caledonian metamorphism.
Details
- Title: Subtitle
- Caledonian eclogite-facies metamorphism of early Proterozoic protoliths from the North-East Greenland eclogite province
- Creators
- Hannes K Brueckner - The Graduate Center, CUNYJane A Gilotti - New York State MuseumAllen P Nutman - Australian National University
- Resource Type
- Journal article
- Publication Details
- Contributions to mineralogy and petrology, Vol.130(2), pp.103-120
- Publisher
- Springer International
- DOI
- 10.1007/s004100050353
- ISSN
- 0010-7999
- eISSN
- 1432-0967
- Language
- English
- Date published
- 01/1998
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229305602771
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