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Partial database for breccia pipes and collapse features on the Colorado Plateau, northwestern Arizona v1.0
A breccia pipe is a vertical, pipe-like mass of broken rock (breccia), typically a few tens of meters across and hundreds of meters in vertical extent. Breccia pipes formed within Paleozoic and Triassic strata over a broad area around the Grand Canyon, and some contain high-grade uranium ore (Wenrich and Titley, 2008). They were created when groundwater (possibly basin brines), flowing through Redwall Limestone dissolution breccias and along fracture zones, dissolved more limestone, causing collapse of overlying rocks and possibly creating sink holes. Some pipes extend many hundreds of meters upward into the Chinle Group (formerly Chinle Formation; Heckert and Lucas, 2003), indicating that some pipes are at least as young as this Upper Triassic rock unit (Brown and Billingsley, 2010). Some pipes are blind and never broke through to the surface. Breccia pipes are abundant in the Grand Canyon region, with at least 1300 pipes or suspected pipes identified (Sutphin and Wenrich, 1989; Brown and Billingsley, 2010). These breccia pipes have been of interest both for their economic value and because they are adjacent to Grand Canyon National Park and the Colorado River (Spencer and Wenrich, 2013).Corrected the spelling of one authors name on the report and uploaded the corrected report on 6/29/2015.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]