RB-SR GEOCHRONOMETRY OF THE ECSTALL, KITKIATA, AND QUOTTOON PLUTONS AND THEIR COUNTRY ROCKS, PRINCE RUPERT REGION, COAST PLUTONIC COMPLEX, BRITISH-COLUMBIA

The minimum age of the Ecstall pluton is 78-79 Ma, based on Rb-Sr mineral isochrons for two pegmatites. The Kitkiata pluton has an initial **8**7Sr/**8**6Sr ratio of 0. 7042-0. 7043, depending on its age. One radiogenic Sr-rich sample gives a model date of 165 plus or minus 11 Ma, but the possibility of anomalous initial ratio makes this result highly uncertain. The Quottoon pluton, which lies a bit farther east of the Ecstall pluton, gives a whole-rock isochron of 51 plus or minus 2 Ma with 0. 7045 plus or minus 1 initial ratio and somewhat older, near concordant, U-Pb zorcon dates of 60 Ma. Radiogenic Sr in schists near Prince Rupert suggests an age of the order of 524 Ma, and correlation with upper Precambrian and lower Paleozoic rocks of the Alexander Terrane of the Alaska Panhandle.