Geological setting and age of the Flemish Cap granodiorite, east of the Grand Banks of Newfoundland

Flemish Cap, a large isolated submarine knoll 600 km east of Newfoundland, consists of a central core of Hadrynian rocks and an onlapping sequence of undisturbed to disturbed Mesozoic–Cenozoic sediments. The central core of the cap, sampled with an electric rock-core drill, comprises pink, fine- to medium-grained granodiorite, dacite, and volcanic siltstone. The granodiorite samples, collected in six out of eight cores, are remarkably similar lithologically, despite a separation of up to 65 km, and probably represent a single pluton. The aphanitic dacite and laminated cherty volcanic siltstone have been metamorphosed to subgreenschist (prehnite) facies but show no evidence of contact metamorphism.U–Pb analyses of coarse and fine zircon fractions from a granodiorite core yielded upper intercepts of 751 and 833 Ma, respectively. Although not precise, these ages probably represent the age of intrusion sometime in the 750–830 Ma range and are older than those reported for similar Hadrynian granitic rocks of e...

[1]  H. Gaudette,et al.  Age of the Brookville Gneiss and associated rocks, southeastern New Brunswick: Reply , 1982 .

[2]  R. T. Haworth,et al.  Geophysical evidence for the extent of the Avalon zone in Atlantic Canada , 1979 .

[3]  S. P. Srivastava.  Evolution of the Labrador Sea and its bearing on the early evolution of the North Atlantic , 1978 .

[4]  R. Steiger,et al.  Subcommission on geochronology: Convention on the use of decay constants in geo- and cosmochronology , 1977 .

[5]  C. J. Hughes.  Volcanogenic cherts in the late Precambrian Conception Group, Avalon Peninsula, Newfoundland , 1976 .

[6]  A. Streckeisen.  To each plutonic rock its proper name , 1976 .

[7]  D. F. Strong,et al.  Geochemistry and tectonic setting of the late Precambrian Holyrood plutonic series of eastern Newfoundland , 1975 .

[8]  V. S. Papezik.  Prehnite-pumpellyite facies metamorphism of late Precambrian rocks of the Avalon Peninsula, Newfoundland , 1974 .

[9]  A. C. Grant.  Geological and geophysical results bearing upon the structural history of the Flemish Cap region , 1973 .

[10]  B. Pelletier.  A Granodioritic Drill Core from the Flemish Cap, Eastern Canadian Continental Margin , 1971 .

[11]  C. J. Hughes,et al.  Late Precambrian Rocks of Eastern Avalon Peninsula, Newfoundland - A Volcanic Island Complex , 1971 .

[12]  H. Lilly.  SUBMARINE EXAMINATION OF THE VIRGIN ROCKS AREA, GRAND BANKS, NEWFOUNDLAND: PRELIMINARY NOTE , 1965 .

[13]  W. Mccartney.  Whitbourne map - area, Newfoundland , 1964 .