Pergamon-Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, Oxon, England
Geochimica et Cosmochimica Acta vol:60 issue:8 pages:1341-1354
The amphibolite to granulite facies transition has been studied in a high-g calc-alkaline, hornblende-biotite, K-feldspar megacrystic augen gneiss series from the Rogaland-Vest-Agder (RogVA) sector of the Sveconorwegian province (southwest Norway). Hornblende begins to break down mainly to clinopyroxene at the Cpx-in isograd and biotite mainly to orthopyroxene at the Opx-in isograd (abbreviations for minerals following Kretz, 1983). The magmatic accessory mineral association comprises titanite and allanite, which begin to break down before the Cpx-in isograd. Titanite is preserved as relict inclusions in other minerals at higher grade. Monazite and thorite formed in the breakdown of allanite. Monazite abundance reaches a maximum between the Cpx-in and Opx-in isograds.