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Geologic map of the Mount Sherman 7.5' quadrangle, Lake and Park Counties, Colorado

Scientific Investigations Map 3271

By:
and
DOI: 10.3133/sim3271

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Abstract

The Mount Sherman 7.5- minute quadrangle is located along the crest of the Mosquito Range in between Leadville and Fairplay, Colorado. There are eleven 13,000-foot peaks and one fourteener, Mount Sherman, within the quadrangle. General elevations range from 10,400–14,036 feet (3,200–4,278 meters). The western half of the quadrangle primarily consists of Proterozoic granitic rocks reverse faulted over Paleozoic sedimentary rocks during the Laramide orogeny of late Cretaceous and Paleocene time. Coeval to this contractional event, sills and laccoliths of the White porphyry group (which probably includes rocks equivalent to the Pando Porphyry) were emplaced in the surrounding country rocks. Igneous activity continued into the Late Eocene with the emplacement of the Sacramento Porphyry (about 43.9 Ma) and the Gray porphyry group (about 36.7 Ma), and as young as 29 Ma to the north within the Climax quadrangle. With the inception of the Rio Grande rift within the region, the Paleozoic sedimentary rocks and Late Cretaceous to early Oligocene igneous rocks were extensionally faulted and tilted to the east. This resulted in the present 20–30 degree dip-slope of these rocks on top of Proterozoic basement rocks within the eastern half of the quadrangle. This extensional regime has continued well into the Pliocene. Within the southwestern quadrant, suspicious lineaments, alignment of springs, and continuous, measureable escarpments provide reasonable evidence for Quaternary tectonic activity along the western flank of the range. Pleistocene glaciers have dramatically sculpted the region, providing exceptional exposure of the region’s bedrock and structure.

Study Area

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geologic map of the Mount Sherman 7.5' quadrangle, Lake and Park Counties, Colorado
Series title:
Scientific Investigations Map
Series number:
3271
DOI:
10.3133/sim3271
Year Published:
2013
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Geosciences and Environmental Change Science Center
Description:
1 Plate: 43.0 x 40.0 inches; Downloads directory
Country:
United States
State:
Colorado
County:
Lake County;Park County
Other Geospatial:
Mount Sherman
Datum:
North American Datum of 1927
Projection:
Universal Transverse Mercator, zone 15
Scale:
24000
Online Only (Y/N):
Y