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Published July 1986 | public
Journal Article

Late Triassic paleogeography of the southern Cordillera: The problem of a source for voluminous volcanic detritus in the Chinle Formation of the Colorado Plateau region

Abstract

The Upper Triassic Chinle Formation of the Colorado Plateau contains voluminous volcanic detritus evidently derived from a source to the south. Volcanic rocks exposed in southern Arizona and northern Sonora have been assumed to represent this source terrane, but U-Pb isotopic geochronology and regional stratigraphic correlations indicate that these volcanic rocks are distinctly younger than the Chinle, and thus not a source for the volcanic detritus in the Chinle. Igneous rocks of known or possible Late Triassic age in Nevada, California, or northeastern Mexico are possible sources, but a clearly defined source terrane for the volcanic detritus in the Chinle has not been identified. Tectonic removal of the source terrane by rifting or strike-slip offset, though not proven, is a possibility.

Additional Information

© 1986 Geological Society of America. Manuscript received November 4, 1985; Revised manuscript received March 17, 1986; Manuscript accepted March 28, 1986. We thank N. J. Silberling and Paul Stone for their reviews of the manuscript and C. M. Conway for his help in collecting and describing the volcanic pebbles and cobbles from the Chinle Formation.

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023