stripes
Occurrence number:
174-00-142
Country:
United States
Region:
Virginia
Location:
Longitude: -79, Latitude: 38.25
Carbonatite:
No
A suite of northwest-trending dykes injected into Palaeozoic sedimentary rocks of the Shenandoah Valley includes teschenites, camptonites, aegirine, nepheline and quartz syenites, spinel-bearing basalts, mica peridotites and olivine dolerites. The alkaline dykes are confined to an elliptical area near Mossy Creek in northwest Augusta County.
Age:
K-Ar on biotite and amphibole separated from nepheline syenite of a dyke northeast of Staunton gave 145 ±7 and 153 ±8 Ma, while Rb-Sr on the same biotite gave 114 ±12 Ma. (Zartman et al., 1967).
References:
JOHNSON, R.W. and MILTON, C. 1955. Dike rocks of central-western Virginia. Bulletin of the Geological Society of America, 66: 1689 (abstract).
ZARTMAN, R.E., BROCK, M.R., HEYL, A.V. and THOMAS, H.H. 1967. K-Ar and Rb-Sr ages of some alkalic intrusive rocks from central and eastern United States. American Journal of Science, 265: 848-70
Location: