|mhorn||Дата: Wednesday, 18.02.2015, 17:22 | Сообщение # 1|
|Cutts J.A., McNicoll V.J., Zagorevski A., Anderson R.G., Martin K. (2015) U-Pb geochronology of the Hazelton Group in the McTagg anticlinorium, Iskut River area, northwestern British Columbia // In: Geological Fieldwork 2014, British Columbia Geological Survey Paper 2015-1, P. 87-101. |
Early to Middle Jurassic rocks of the Hazelton Group are extensively mineralized, including the precious metal-rich Eskay Creek deposit that is hosted by bimodal volcanic successions in the Eskay rift. In this study, we present U-Pb zircon ages of seven Hazelton Group volcanic, epiclastic and hypabyssal rocks to establish the absolute ages of Hazelton Group units in the McTagg anticlinorium, east of the Eskay Creek deposit. A felsic volcaniclastic sample from the Brucejack Lake member (Betty Creek Formation) yielded a 187.1±1.9 Ma U-Pb crystallization age that is consistent with previous fossil and U-Pb age determinations. Six samples from the Bruce Glacier member (Iskut River/Salmon River Formation) yielded U-Pb crystallization ages of 178.5±1.8, 174.6±1.8, 174.4±1.7, 174.7±1.8, 173.6±1.7, and 173.3±1.8 Ma. These ages indicate that volcanic rocks coeval with the Eskay member occur in the McTagg anticlinorium, as far south as Mt. Dilworth.
Middle Jurassic - Lower Cretaceous ammonites & aptychi