2010 GSA Denver Annual Meeting (31 October –3 November 2010)
404 Friday, 29 October 2010
7:30 AM-6:00 PM, Colorado Convention Center: Lobby B

Behind Colorado’s Front Range – A new look at Laramide basin subsidence, sedimentation, and deformation in central Colorado

Primary Leader: James C. Cole
Leader(s): Patricia Cashman, M.A. Cosca, Ian M. Miller, Ralph R. Shroba, James H. Trexler Jr, Jeremiah B. Workman
Field Trip Description: The early Tertiary uplift history of Colorado’s Front Range has been well documented by detailed studies of stratigraphy, sedimentology, and paleobotany from the Laramide-age Denver Basin along the eastern range flank. This field trip examines contrasting and comparative evidence from the “back-side” of the Front Range in the elongate structural basin underlying the Middle Park and North Park physiographic areas. We’ll visit sections in the Paleogene Middle Park Formation and (largely coeval) Coalmont Formation to examine evidence of sedimentation, depositional environments, source areas, paleogeography, isotopic ages, paleobotany, and related topics. This excursion will present results from an entirely new, interdisciplinary investigation of the area that challenges major elements of conventional thinking about the timing and structural controls of basement-block uplift during the Laramide orogeny. For example, internal unconformities within the Middle Park Formation suggest that local basement blocks adjoining the broad structural swale were moving independent of each other, chiefly in vertical directions. Additional stops explore sedimentology of the Coalmont Formation within the North Park basin, including lacustrine delta complexes and coal mires. Geometry of post-Coalmont folding and faulting is described in the context of uplift of surrounding basement blocks. New exploration in the last two years has produced oil from stratigraphic targets that hints at wider potential in the basin. Friday night poster presentations and discussions at accommodations in Walden, Colorado, will cover wide-ranging topics including Neogene volcanism, drainage integration, and Quaternary history of the region. All field-trip stops are roadside; limited walking/hiking is involved. Great scenery included.
Field Trip will span: 2 days
Sponsor(s): GSA Sedimentary Geology Division

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