2010 GSA Denver Annual Meeting (31 October 3 November 2010)
407 Saturday, 30 October 2010
7:30 AM-5:00 PM, Colorado Convention Center: Lobby B

Mechanisms of post-Laramide fracturing in the Rockies: insights from outcrops and industry data from the northern Denver Basin, Colorado

Primary Leader: Eric A. Erslev
Leader(s): Cody Lee Allen, Bryan W. Richter
Field Trip Description: The orientations and intensities of open fractures are critically important to water and petroleum production as well as CO2 sequestration in the U.S. Rocky Mountains. Post-Laramide fractures commonly form dominant fluid pathways, and a better understanding of their mechanisms is needed to predict reservoir heterogeneities and site horizontal wells. Unfortunately, a multitude of potential fracture-forming processes has been documented, including several periods of regional extension and more localized backsliding on Laramide thrusts, gravity detachments into basins, petroleum maturation, and erosional denudation. This field trip will examine extensional fractures in outcrops of the Niobrara Formation and adjacent units along the Front Range between Boulder and Fort Collins. The Niobrara Formation is an important resource play due to in situ trapping of oil generated in its source beds. Moderate walks to excellent exposures will show a complex fracture history, with minor faults, splitting fractures and styolites due to Laramide shortening overprinted by, and sometimes reactivated by, post-Laramide normal faults and extensional fractures. We will also present 3-D seismic and well data from the Denver Basin showing the fundamentally different orientations and styles of fracturing on the western and eastern sides. The results of other industry-academic collaborations from elsewhere in the Rockies will be used to demonstrate the multiple ages and mechanisms of Rocky Mountain fracturing. These hypotheses will be debated on the outcrop a lively discussion in beautiful scenery is guaranteed!
Field Trip will span: 1 day
Sponsor(s): GSA Division of Structural Geology and Tectonics; GSA Division of Geophysics; Colorado Scientific Society

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