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Geologic map of the Leadville North 7.5’ quadrangle, Eagle and Lake Counties, Colorado

May 18, 2018

The Leadville North 7.5’ quadrangle lies at the northern end of the Upper Arkansas Valley, where the Continental Divide at Tennessee Pass creates a low drainage divide between the Colorado and Arkansas River watersheds. In the eastern half of the quadrangle, the Paleozoic sedimentary section dips generally 20–30 degrees east. At Tennessee Pass and Missouri Hill, the core of the Sawatch anticlinorium is mapped as displaying a tight hanging-wall syncline and foot-wall anticline within the basement-cored structure. High-angle, west-dipping, Neogene normal faults cut the eastern margin of the broad, Sawatch anticlinorium. Minor displacements along high-angle, east- and west-dipping Laramide reverse faults occurred in the core of the north-plunging anticlinorium along the western and eastern flanks of Missouri Hill. Within the western half of the quadrangle, Meso- and Paleoproterozoic metamorphic and igneous rocks are uplifted along the generally east-dipping, high-angle Sawatch fault system and are overlain by at least three generations of glacial deposits in the western part of the quadrangle. 10Be and 26Al cosmogenic nuclide ages of the youngest glacial deposits indicate a last glacial maximum age of about 21–22 kilo-annum and complete deglaciation by about 14 kilo-annum, supported by chronologic studies in adjacent drainages. No late Pleistocene tectonic activity is apparent within the quadrangle.

Publication Year 2018
Title Geologic map of the Leadville North 7.5’ quadrangle, Eagle and Lake Counties, Colorado
DOI 10.3133/sim3400
Authors Chester A. Ruleman, Theodore R. Brandt, Marc W. Caffee, Brent M. Goehring
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Scientific Investigations Map
Series Number 3400
Index ID sim3400
Record Source USGS Publications Warehouse
USGS Organization Geosciences and Environmental Change Science Center