Evidence and dating of mid-Cretaceous tectonic activity in the San Rafael Swell, Emery County, Utah
- Museum of Northern Arizona, Flagstaff (USA)
- Univ. of Nebraska, Lincoln (USA)
- Univ. of Colorado, Boulder (USA)
Evidence of tectonic activity in the form of recycled conglomerates has been found in middle Cretaceous deposits on the western flank of the San Rafael Swell. These conglomerates, present in the upper part of the Dakota Formation and in the overlying basal Mancos Shale (Tununk Member), are separated by an earliest Turonian unconformity. The conglomerates appear to be derived from the Lower Cretaceous Buckhorn Conglomerate, or similar conglomerates, which were re-exposed by latest Cenomanian uplift. Coarse clastics provided to the nearshore facies of the Dakota Formation by coastal rivers are preserved as a coarsening upward sequence. Continued uplift eventually caused a local marine regression by temporarily inhibiting the initial (latest Cenomanian) transgression of the Greenhorn Sea. In subaerially exposed environments pebbles and cobbles from the Buckhorn were distributed across the coastal floodplain by rivers. These clasts were reworked into a basal lag deposit when renewed transgression of the Greenhorn Sea occurred during the late early Turonian.
- OSTI ID:
- 6224888
- Journal Information:
- Mountain Geologist; (USA), Vol. 27:2; ISSN 0027-254X
- Country of Publication:
- United States
- Language:
- English
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