Fracture history of the southern Piceance basin and tectonic development of intrabasin folds, northeastern Colorado plateau, Colorado
The Piceance structural and depositional basin, northwestern Colorado, contains strata that are petroleum reservoirs where fluid flow is fracture controlled. The relative age of fracture sets and their distribution in the southern Piceance basin are related to the tectonic history of the area. Two sets of only local significance on an intrabasin anticline are a result of Laramide (late Eocene) thrusting; the other regional sets are younger and formed sequentially, in part, in a rotational stress field. Five regional sets of extension fractures (joints), designated F{sub 1} (oldest)-F{sub 5}, occur in Upper Cretaceous through Middle Eocene basin strata; these collectively define the Piceance system. Two older sets, designated MV{sub 1} (oldest)-MV{sub 2}, occur along the Grand Hogback and define the Hogback system. In the basin, F{sub 1} fractures are large but sparse, F{sub 2} fractures dominate the northern two-thirds of the basin, F{sub 3} fractures are common in the southern half, F{sub 4} fractures are found throughout the basin, and F{sub 5} fractures are everywhere sparse. The distribution of the fracture systems relative to stratigraphic level varies across the basin. In and near the Grand Hogback, joints of the Hogback system occur in Tertiary and older strata. In contrast, in correlative strata near the western margin of the basin, only joints of the Piceance system are found. Paleozoic block faulting affected the Precambrian basement and overlying Cambrian through Middle Pennsylvanian evaporitic rocks. Late in the Laramide, basin shortening was accommodated between these evaporites and the Upper Cretaceous sandstones by splay faults above a decollement that developed in front of a southwest-moving thrust wedge that forced the folding of the Grand Hogback above it. The splay faults died out upsection and overthickened the Mancos Shale, thus shaping the Divide Creek anticine.
- Research Organization:
- Colorado Univ., Boulder, CO (United States)
- OSTI ID:
- 6131161
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
AGE ESTIMATION
ANTICLINES
COLORADO
DEPOSITION
DEVELOPED COUNTRIES
DISTRIBUTION
FEDERAL REGION VIII
FLUID FLOW
FLUIDS
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
MINERAL RESOURCES
NORTH AMERICA
ORIGIN
PETROLEUM DEPOSITS
PICEANCE CREEK BASIN
RESERVOIR FLUIDS
RESERVOIR ROCK
RESOURCES
STRATIGRAPHY
TECTONICS
USA
WATERSHEDS