Minturn and Sangre de Cristo Formations of southern Colorado: a prograding fan-delta to alluvial-fan sequence shed from ancestral Rocky Mountains
The Pennsylvanian Minturn and Pennsylvanian-Permian Sangre de Cristo Formations of the northern Sangre de Cristo Mountains comprise a 3,800-m (12,500-ft) thick progradational sequence of coarse clastic sediments shed into a basin on the northeastern side of the late Paleozoic San Luis-Uncompahgre highland. From bottom to top, the mostly marine Minturn Formation contains probable deltaic (700 m, 2,300 ft), mixed fan-delta and prodelta (800 m, 2,600 ft), and fan-delta (600 m, 2,000 ft) deposits; the mostly continental Sangre de Cristo Formation contains distal alluvial fan (600 m, 2,000 ft) and proximal alluvial fan (1,100m 3,600 ft) deposits. At least three episodes of uplift are indicated by the distribution of unconformities, geometry of intertonguing facies, and abrupt vertical changes in facies. The deltaic and mixed fan-delta and prodelta deposits of the lower and middle parts of the Minturn Formation consist of coarsening-upward cycles 30 to 300 m (100 to 1,000 ft) thick of shale, siltstone, sandstone, and conglomeratic sandstone. The mixed deposits in the middle part of the Minturn contain cycles of shale, proximalturbidite sandstones, and conglomeratic sandstone; such cycles are interpreted as deposits of submarine fans overridden by fan deltas. Continental deposits of the lower member of the Sangre de Cristo Formation consist of fining-upward cycles 2 to 37 m (6.5 to 121 ft) thick of cross-bedded conglomerate, sandstone, and siltstone deposited by braided streams on the distal parts of alluvial fans.
- Research Organization:
- Geological Survey, Denver, CO
- OSTI ID:
- 6351788
- Report Number(s):
- CONF-8309274-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:8; Conference: AAPG Rocky Mountain Section meeting, Billings, MT, USA, 18 Sep 1983
- Country of Publication:
- United States
- Language:
- English
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