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The AAPG/Datapages Combined Publications Database

CSPG Bulletin

Abstract


Journal of the Alberta Society of Petroleum Geologists
Vol. 10 (1962), No. 6. (June), Pages 320-325

Potassium-Argon Mineral Dates from the Mannville Group

G. D. Williams, H. Baadsgaard, G. Steen

ABSTRACT

Detrital orthoclase and authigenic glauconite from the Lower Cretaceous Mannville Group of central Alberta has been dated by the K-Ar Method. One sample of detrital feldspar from the McMurray Formation is dated in the range from 1350 to 1550 m.y. Seven samples of glauconite from the Clearwater Formation give an average date of 95 m.y. Two samples of detrital feldspar from the Grand Rapids Formation are dated in the range 120 to 150 and 160 to 220 m.y.

Feldspar in the McMurray Formation was almost certainly derived from the Precambrian Shield, whereas feldspar in the Grand Rapids Formation was probably derived from Mesozoic rocks in the Cordillera. Glauconite from the intervening Clearwater Formation gives a minimum date for the time of deposition of the enclosing rocks, and seems to be an unreliable mineral for accurate K-Ar dating.


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