Constraints on Pb closure temperature in titanite based on rocks from the Ungava orogen, Canada: Implications for U-Pb geochronology and P-T-t path determinations
- 1Centre de Recherche en Géochimie Isotopique et en Géochronologie (GEOTOP), Université du Québec à Montréal, Case Postal 8888, Succursale Centreville, Montréal, Québec H3C 3P8, Canada
- 2Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada
Abstract
On the basis of multiequilibrium metamorphic pressure-temperature (P-T) estimates, we have determined that 660–700 °;C is a reasonable minimum estimate of the closure T of Pb diffusion in titanite, a temperature significantly higher than previously suggested. Activity-corrected reactions that produce titanite define narrow T stability fields (≈40 °;C) that correspond closely to metamorphic P-T determinations derived for coronitic garnet-clinopyroxene-hornblende samples. Growth of titanite, occurring between 1789 and 1814 Ma in the underthrust Archean basement of the Paleoproterozoic Ungava orogen (northern Quebec), is associated with retrograde metamorphism during underthrusting of the Archean basement (Approx.)1 b.y. after formation of the original granulitic assemblages.
Footnotes
- Geological Society of America
