U-Pb age analyses on zircon grains from Mount Lawson Formation bentonites (Ellesmere Island)

LA-ICP-MS analyses on zircon grains from Mount Lawson Formation bentonites (Ellesmere Island). Analyses listed from lowest to highest 206Pb/238U age for <1000 Ma and lowest to highest 207Pb/206Pb age for >1000 Ma. Spot nomenclature follows the scheme x-y.z: with x=sample number, y=grain, z=spot. Disc.: per cent discordance for the given 207Pb/206Pb age. Error correl.: Error correlation coefficient for concordia coordinates. Concordia coordinates: y = 206Pb/238U = EXP(L238*(206-238 Age)) - 1; x = 207Pb/235U = EXP(L235 × (207-235 Age)) - 1; 207Pb/206Pb = 137.88 × x/y; Uranium decay constants (L238 & L235) are from (Jaffey et al., 1971). L238 = 1.55125 × 10-4/Ma; L235 = 9.8485 × 10-4/Ma. Reference: Jaffey, A., K. Flynn, L. Glendenin, W. Bentley, and A. Essling (1971), Precision Measurement of Half-Lives and Specific Activities of 235U and 238U, Phys. Rev. C, 4(5), 1889-1906.