Analytical method: UNKNOWN
| Technique | UNKNOWN |
|---|---|
| Material | WHOLE ROCK |
| Mineral | none |
| Institution | Unknown, Unknown, USA |
| Reference | Nixon, G T; Demant, A; Armstrong, R L; Harakal, J E (1987) K-Ar and geologic data bearing on the age and evolution of the Trans-Mexican volcanic belt. Geofisica Internacional. 26; 1, Pages 109-158. 1987. |