Mg-Al Yttrian Zirconolite in a Partially Melted Sapphirine Granulite, Vestfold Hills, East Antarctica

Simon L. Harley
Department of Geology and Geophysics, Grant Institute, Kings Buildings, West Mains Road, Edinburgh, Scotland, EH9 3JW

Abstract: A new compositional variety of zirconolite characterized by high Mg, Al, Y2O3 and REE, and low Fe is described from a sapphirine granulite xenolith entrained in an intrusive norite body which was emplaced into the late Archaean (2520–2480 Ma) Vestfold Hills high-grade terrain during the early Proterozoic. The zirconolite, and similarly Mg-Al rich perrierite-(Ce), formed as a result of sanidinite facies partial melting of the particularly magnesian and aluminous sapphirine granulite xenolith during its incorporation into the c. 1170°C basic magma at c. 2240 Ma. The high REE compared to Al cations require that a previously unrecognized coupled substitution: REE.REE.(Mg,Fe).Ca−2.Ti−1 occurs in this zirconolite. Full chemical analyses are presented for zirconolite and perrierite from this unique occurrence.

Keywords: zirconolite • perrierite-(Ce) • granulite • Vestfold Hills

Mineralogical Magazine; June 1994 v. 58; no. 391; p. 259-269; DOI: 10.1180/minmag.1994.058.391.08
© 1994, The Mineralogical Society
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