Table 1.

Compilation of Rigolet mineral assemblages and estimated metamorphic conditions, U–Pb ages of metamorphism, and 40Ar/39Ar Hbl cooling ages in the Parautochthonous Belt (PB)

Location W→E, pMP/pHPAssemblagesEstimated PTt of metamorphismReferencesComments
20 km transect from GF near Killarney (Ontario) SE into GFTZ [pMP]Granitic ogn, pgn, amphibolite – Ttn and Hbl-bearing assemblages11 U–Pb Ttn analyses lie on chord with UI at 1450 Ma at GF and LI at 978 Ma 20 km SE of GF. Ar Hbl plateau ages from 993–979 MaHaggart et al. 1993; Krogh 1994c. 0.98 Ga Ttn rims on 1.45 Ga Ttn (or Pb loss?) Hbl plateau ages 15 km SE of GF (partially reset older ages near GF)
c. 30 km SE GFTZ, Georgian Bay, (Ontario) [pMP]Garnet amphibolite: Grt-Pl-Hbl-Bt-Qtz-Ilm-Spl≥1100 MPa/750 °C c. 990–980 Ma. Ar Hbl ages from 980–960 MaCulshaw et al. 1991; Jamieson et al. 1995; Reynolds et al. 1995Quasi-isothermal decompression path in southern GFTZ
NW GFTZ (between Killarney and Sudbury, Ontario) [pMP]Metabasite: Grt-Cpx-Pl-Opx-Qtz-Hbl-Spl630 MPa/710 °C c. 7 km SE of GF, 830 MPa/730 °C c. 16 km SE of GF. 1.0 Ga overgrowths of metamorphic Zrn on igneous BdyDavidson & van Breemen 1988; Dudás et al. 1994; Bethune 1997; Bethune & Davidson 1997Metamorphic field gradient SE of GF
GFTZ SE of Val d'Or (W. Québec) [pMP and pHP]Metabasite: Grt-Cpx-Pl-Opx-Qtz-Hbl1200–1500 MPa/800 °C to 900 MPa/700 °C c. 1 Ga (Mnz) Ar Hbl ages c. 995 MaIndares & Martignole 1989; Gariépy et al. 1990; Childe et al. 1993; Martignole & Reynolds 1997; Martignole & Martelat 2005Quasi-isothermal decompression path. Grenvillian Mnz in southern PB
Gagnon terrane (E. Québec) [pMP and pHP]Pelite: Qtz-Ms-Bt-Grt-Ky-Pl-Lc. 1400 MPa/>800 °C 995–985 MaIndares 1995; Jordan et al. 2006Bt dehydration melting followed by melt crystallization
Gagnon terrane (near Wabush, W. Labrador) [pMP]Pelite: Mfg from Qtz-Chl-Bt to Qtz-Ms-Bt-Grt-Ky-Pl-Lc. 600 MPa/450 °C 10 km SE of GF to c. 1100 MPa/750 °C 30 km SE of GF. c. 1 Ga (Zrn, Mnz) Ar Hbl ages c. 960–940 MaRivers 1983a, b; Dallmeyer & Rivers 1983; van Gool et al. 2008; Rivers et al. 1995, 2002; Cox & Rivers in pressInverted metamorphic field gradient in thrust stack SE of GF
Molson Lake terrane [pHP]Prg-Cpx-Opx-Grtcoronas separating Ol and Pl (Ky inclusions in Pl; ≤51% Jd in Cpx)1200–1400 MPa, 700–750 °C in NW, 1600–1800 MPa, 800–850 °C in SE. Zrn LI c. 1005 Ma; Ar Hbl cooling ages 940–905 MaDallmeyer & Rivers 1983; Rivers & Mengel 1988; Connelly & Heaman 1993; Indares & Rivers 1995; Connelly et al. 1995Coronitic textures. Metamorphic field gradient from NW to SE.
Smokey ArchipelagoMafic to intermediate560–630 °C, P undeterminedOwen et al. 1986, 1988;Negligible Grenvillian
(E. Labrador) [pMP]orthogneiss: Grt-Hbl-Bt-Pl-Qtzc. 1040–1030 Ma (Zrn: LI)Krogh et al. 2002Zrn and Mnz near GF
  • Abbreviations: pMP, medium pressure; pHP, high pressure; GF, Grenville Front; GFTZ, Grenville Front Tectonic Zone; mfg, metamorphic field gradient; ogn, orthogneiss; pgn, paragneiss; Bdy, Baddeleyite; Bt, biotite; Cpx, clinopyroxene; Grt, garnet; Hbl, hornblende; Ilm, ilmenite; Jd, jadeite; Ky, kyanite; L, leucosome (granitic liquid); Mnz, monazite; Ms, muscovite; Ol, olivine; Opx, orthopyroxene; Pl, plagioclase; Qtz, quartz; Spl, spinel; Ttn, titanite; Zrn, zircon. LI, UI, lower and upper intercepts on concordia.