National Geochronological Database sample #8724

Outcrop or artificial surface exposure, Hydrothermal alteration

Geographic location
-122.083333, 46.35
122° 5' " W, 46° 21' " N
Skamania county, WA
Mount Spirit Lake 1:62,500 scale map quadrangle
Accurate to within 1 minute (~1 mile)
Source of sample Outcrop or artificial surface exposure
Rock name Hydrothermal alteration
Description BIOTITE-QUARTZ-TOURMALINE-PLAGIOCLASE ZONE NEAR BORDER OF QUARTZ DIORITE PORPHYRY, EARL STOCK
Laboratories University of British Columbia
Compiler name Marvin, R.F.
Date compiled 1980 11
Precision of location Accurate to within 1 minute (~1 mile)
Bibliographic reference Armstrong, R.L., Harakel, J.E., and Hollister, V.F., 1976, Age Determination Of Late Caenozoic Porphyry Copper Deposits Of The North American Cordillera: Institution of Mining and Metallurgy, Transactions, Section B: Applied Earth Science, v. 85, p. B239-B244.
(click for info)
Geologic map unit -122.083333, 46.35
Nearby scientific data Find additional scientific data near this location

K-Ar age determinations

Age estimate 16.61 ± 0.6Ma
Type of analysis conventional K-Ar
K=5.92%
Rock or mineral analyzed biotite
Analytical details
Lab sample ID EARL
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 7.13 %
Radiogenic 40Ar concentration 1.713
Radiogenic Ar 66 %
Comments PROBABLE TIME OF HYDROTHERMAL ALTERATION