USGS

Isotopically dated rock units discussed in text
Figure 3. The locations of isotopically (radiometrically) dated rock units discussed in text.
Sample number
Rock unit
Age (Ma)
Age-dating technique
Reference
1
Jd
200
40Ar/39Ar
Kunk and others (1992).
2
Zcr
564+-9
U/Pb
Aleinikoff and others (1995).
3
Zrd
571.5+-4.7
U/Pb
Aleinikoff and others (1995).
4
Ybg
1055+-5
U/Pb
Aleinikoff and others (1993).
5
Ygt
1070
U/Pb
Aleinikoff and others (1993).
6
Yhg
1110
U/Pb
Aleinikoff and others (1993).

U.S. Geological Survey, U.S. Department of the Interior
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Contact: Scott Southworth
Last modified 08.29.00