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Depositional environments as a guide to uranium mineralization in the Chinle Formation, San Rafael Swell, Utah

January 1, 1994

Uranium deposits in the San Rafael Swell are related to sedimentary depositional environments in the Triassic Chinle Formation. The sedimentary textures resulting from depositional processes operating in lower energy environments appear to have influenced uranium mineralization. The Chinle consists of three fining-upward, fluvial-lacustrine sequences. Uranium mineralization is concentrated in the lower part of the lowest sequence in areas where sediments of lower energy environments are complexly interbedded with sediments of other environments. Areas favorable for uranium exploration exist in the subsurface to the north, west, and south of the Chinle outcrop in the Swell. This determination is based on the spatial distribution of depositional environments and the pattern of Chinle deposition through time.