A New Natural Occurrence of Zirconolite (CaZrTi2O7) and Baddeleyite (ZrO2) in Basic Cumulates: The Laouni Layered Intrusion (Southern Hoggar, Algeria)

J. P. Lorand and J. Y. Cottin
Laboratoire de Minéralogie du Museum National d'Histoire, Naturelle de Paris, Unité associée au CNRS no. 286, 61 Rue Buffon, 75005 Paris, France
Départment de Géologie, IST Université d'Oran Essenia, Algeria

Abstract: Four grains of zirconolite and baddeleyite have been found in two plagioclase-rich adcumulates from the Laouni layered intrusion (Southern Hoggar, Algeria). Zirconolite is poor in REE; baddeleyite is chemically close to ZrO2 and contains minor amounts of Hf. They are considered to be crystallization products of pockets of intercumulus liquid. The preferential distribution of zirconolite in anorthosite is explained in terms of expulsion of the intercumulus liquid by sintering or annealing of plagioclase. The crystallization of baddeleyite reflects the sharp increase of Zr in the trapped intercumulus liquid.

Keywords: zirconolite • baddeleyite • cumulate texture • Laouni • Hoggar • Algeria

Mineralogical Magazine; December 1987 v. 51; no. 363; p. 671-676; DOI: 10.1180/minmag.1987.051.363.06
© 1987, The Mineralogical Society
Mineralogical Society (www.minersoc.org)