Geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana
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- Document: Report (3.75 MB pdf)
- Plates:
- Sheet 1 (18.4 MB pdf) Geologic Map of the Strawberry Butte 7.5’ Quadrangle, Meagher County, Montana
- Sheet 1, georeferenced (25.1 MB pdf) Geologic Map of the Strawberry Butte 7.5’ Quadrangle, Meagher County, Montana
- Sheet 2 (164 kB pdf) Geologic Map of the Strawberry Butte 7.5’ Quadrangle, Meagher County, Montana
- Data Release: USGS data release – Data release for the geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana
- Read Me: Read Me (12.0 kb txt)
- Download citation as: RIS | Dublin Core
Abstract
The 7.5′ Strawberry Butte quadrangle in Meagher County, Montana near the southwest margin of the Little Belt Mountains, encompasses two sharply different geologic terranes. The northern three-quarters of the quadrangle are underlain mainly by Paleoproterozoic granite gneiss, across which Middle Cambrian sedimentary rocks rest unconformably. An ancestral valley of probable late Eocene age, eroded northwest across the granite gneiss terrane, is filled with Oligocene basalt and overlying Miocene and Oligocene sandstone, siltstone, tuffaceous siltstone, and conglomerate. The southern quarter of the quadrangle is underlain principally by deformed Mesoproterozoic sedimentary rocks of the Newland Formation, which are intruded by Eocene biotite hornblende dacite dikes. In this southern terrane, Tertiary strata are exposed only in a limited area near the southeast margin of the quadrangle. The distinct terranes are juxtaposed along the Volcano Valley fault zone—a zone of recurrent crustal movement beginning possibly in Mesoproterozoic time and certainly established from Neoproterozoic–Early Cambrian to late Tertiary time. Movement along the fault zone has included normal faulting, the southern terrane faulted down relative to the northern terrane, some reverse faulting as the southern terrane later moved up against the northern terrane, and lateral movement during which the southern terrane likely moved west relative to the northern terrane. Near the eastern margin of the quadrangle, the Newland Formation is locally the host of stratabound sulfide mineralization adjacent to the fault zone; west along the fault zone across the remainder of the quadrangle are significant areas and bands of hematite and iron-silicate mineral concentrations related to apparent alteration of iron sulfides. The map defines the distribution of a variety of surficial deposits, including the distribution of hematite-rich colluvium and iron-silicate boulders. The southeast corner of the quadrangle is the site of active exploration and potential development for copper from the sulfide-bearing strata of the Newland Formation.
Suggested Citation
Reynolds, M.W., and Brandt, T.R., 2017, Geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana: U.S. Geological Survey Scientific Investigations Map 3379, pamphlet 16 p., 2 sheets, scale 1:24,000, https://doi.org/10.3133/sim3379.
ISSN: 2329-132X (online)
Study Area
Table of Contents
- Abstract
- Geologic Setting
- Stratigraphy
- Structure
- Summary
- Acknowledgments
- Description of Map Units
- References Cited
Publication type | Report |
---|---|
Publication Subtype | USGS Numbered Series |
Title | Geologic map of the Strawberry Butte 7.5’ quadrangle, Meagher County, Montana |
Series title | Scientific Investigations Map |
Series number | 3379 |
DOI | 10.3133/sim3379 |
Year Published | 2017 |
Language | English |
Publisher | U.S. Geological Survey |
Publisher location | Reston, VA |
Contributing office(s) | Geosciences and Environmental Change Science Center |
Description | Report: iii, 16 p.; 3 Sheets: 37.53 x 33.04 inches or smaller; Data Release; Read Me |
Country | United States |
State | Montana |
County | Meagher County |
Online Only (Y/N) | Y |
Google Analytic Metrics | Metrics page |