This article from the New Mexico Geological Society Guidebook contains information about Late Cretaceous (73.8-70.65 Ma) ages for hornblende separates from the Carrizo Mountains laccolith. Three specimens of diorite porphyry were examined using the 40Ar/39Ar step-heating method and no evidence of excess 40Ar or contamination by older xenocrysts was found. This has called into question some previously published K-Ar ages from the Four Corners area. This article thus confirms that the Carrizo Mountains intrusive center is an Arizona extension of the Laramide-age Colorado mineral belt.
This resource is referenced here:Subject:
Geoscience:Geology:Igneous and Metamorphic Petrology:Igneous Associations and Tectonic Settings,
Geoscience:Geology:Tectonics,
Structural Geology:Regional Structural/Tectonic Activity
Resource Type:
Scientific Resources:Research Results, Journal Article
Topics:
Solid Earth:Structural Geology:Regional Structural/Tectonic Activity,
Solid Earth:Petrology:Igneous Associations and Tectonic Settings, Solid Earth
