Polymetamorphism in the NE Shackleton Range, Antarctica: Constraints from Petrology and U---Pb, Sm---Nd, Rb---Sr TIMS and in situ U---Pb LA-PIMMS Dating

include garnet with contrasting zonation patterns and two age spectra. Garnet porphyroblasts in K-rich kyanite---sillimanite---staurolite---garnet---muscovite---biotite schists from Lord Nunatak show prograde growth zonation, and give Sm---Nd garnet, U---Pb monazite and Rb---Sr muscovite ages of 518...

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Bibliographic Details
Main Authors: A. Zeh, I. L. Millar, M. S. A. Horstwood, Metapelitic Ne, Shackleton Range
Other Authors: The Pennsylvania State University CiteSeerX Archives
Format: Text
Language:English
Published: 2003
Subjects:
Lord Nunatak
Meade
Meade Nunatak
Shackleton
Shackleton Range
Antarc*
Antarctica
Online Access:http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.523.5657
http://petrology.oxfordjournals.org/content/45/5/949.full.pdf
Description
Summary:include garnet with contrasting zonation patterns and two age spectra. Garnet porphyroblasts in K-rich kyanite---sillimanite---staurolite---garnet---muscovite---biotite schists from Lord Nunatak show prograde growth zonation, and give Sm---Nd garnet, U---Pb monazite and Rb---Sr muscovite ages of 518 5, 514 1 and 499 12Ma, respectively. Geothermobarometry and P---T pseudo-section calculations in the model system CaO---Na2O---K2O---TiO2---MnO---FeO---MgO---Al2O3---SiO2---H2O are consistent with garnet growth during prograde heating from 540C/7 kbar to 650C/75 kbar, and partial resorption during a subsequent P---T decrease to 5650C at 56 kbar. All data indicate that rocks from Lord Nunatak were affected by a single orogenic cycle. In contrast, garnet porphyroblasts in K-poor kyanite---sillimanite---staurolite---garnet---cordierite---biotite-schists from Meade Nunatak show two growth stages and diffusion-controlled zonation. Two

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