Data release for Geologic Map of the Leadville North 7.5' quadrangle, Eagle and Lake Counties, Colorado
Dates
Publication Date
2018-04-19
Time Period
2018
Citation
Ruleman, C.A., Brandt, T.R., Goehring, B.M., and Caffee, M.A., 2018, Data release for Geologic Map of the Leadville North 7.5' quadrangle, Eagle and Lake Counties, Colorado: U.S. Geological Survey data release, https://doi.org/10.5066/F7DR2TRG.
Summary
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 [...]
Summary
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.
Land-use planners of many kinds (including National Forest managers, developers, city and rural planners, and highway builders) need accurate geologic data with which to make informed decisions. The Leadville North quadrangle is designed to meet this requirement. The map is also part of the National Geologic Database, which is intended as digital framework for the entire country. From a scientific standpoint, the map clarifies many structural and lithologic relationships at the northern end of the Upper Arkansas River Valley, showing relationships between Laramide contractional faults and Rio Grande rift extensional faults. Tectono-magmatic relationships are also shown with the four ages of intrusive rocks. Cosmogenic nuclide data provides absolute age constraints on late Pleistocene deposits for further geomorphic and seismotectonic studies.
