Geologic map of the Lead Mountain 15’ quadrangle, San Bernardino County, California
Geologic Quadrangle
1766
Links
- More information: USGS Index Page (html)
- Document: Report (pdf)
- Plate: Gq 1766 (pdf)
- NGMDB Index Page: National Geologic Map Database Index Page (html)
- Download citation as: RIS | Dublin Core
Abstract
The Lead Mountain 15’ quadrangle in the Mojave Desert contains a record of Jurassic, Cretaceous, Tertiary, and Quaternary magmatism. Small amounts of Mesoproterozoic(?) augen gneiss and Paleozoic and Mesozoic(?) metasedimentary rocks are preserved in small patches; they are intruded by voluminous Jurassic plutons of quartz diorite to granite composition and by Late Cretaceous granite of the Cadiz Valley batholith. Jurassic intrusive rocks include part of the Bullion Mountain Intrusive Suite and also younger dikes inferred to be part of the Jurassic Independence dike swarm. A contact-metamorphosed aureole 2 km wide in the Jurassic plutonic rocks fringes the Cadiz Valley batholith. Early Miocene dacitic magmatism produced a dense swarm of dikes in the eastern Bullion Mountains and the volcanic-intrusive remnant of a volcano at Lead Mountain. Tilting of the dike swarm from inferred vertical orientations may have resulted from Miocene tectonic extension. Conglomerate of Pliocene and (or) Miocene age is also tilted. Younger volcanism is recorded by Pliocene basalt of the Deadman Lake volcanic field, basalt of Lead Mountain (approximately 0.36 Ma), and the even younger basalt of Amboy. Quaternary sedimentation built alluvial fans and filled playas in the map area. Faulting in the dextral eastern California shear zone produced several northwest-striking faults in the quadrangle, some of them active into the Pleistocene and some that may have many kilometers of right-lateral offset.
Study Area
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Geologic map of the Lead Mountain 15’ quadrangle, San Bernardino County, California |
| Series title | Geologic Quadrangle |
| Series number | 1766 |
| DOI | 10.3133/gq1766 |
| Year Published | 2013 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Contributing office(s) | Geology, Minerals, Energy, and Geophysics Science Center |
| Description | Pamphlet: ii, 17 p.; 1 Plate: 30.68 × 33.11 inches |
| Country | United States |
| State | California |
| County | San Bernardino County |
| Other Geospatial | Lead Mountain 15' quadrangle |
| Scale | 62500 |
| Online Only (Y/N) | Y |
| Additional Online Files (Y/N) | Y |
| Google Analytic Metrics | Metrics page |