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

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 regio...

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Bibliographic Details
Published in:Geology (Boulder) 1986-07, Vol.14 (7), p.567-570
Main Authors: Stewart, John H, Anderson, Thomas H, Haxel, Gordon B, Silver, Leon T, Wright, James E
Format: Article
Language:English
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Summary: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.
ISSN:0091-7613
DOI:10.1130/0091-7613(1986)142.0.CO;2