Geology, age, and tectonic setting of the Cretaceous SliderockMountain Volcano, Montana
du Bray, Edward A; Harlan, Stephen S (1998) Geology, age, and tectonic setting of the Cretaceous SliderockMountain Volcano, Montana. U. S. Geological Survey Professional Paper, Report: P 1602, 19 pp.,1998
| Authors | du Bray, Edward A; Harlan, Stephen S |
|---|---|
| Year | 1998 |
| Title | Geology, age, and tectonic setting of the Cretaceous SliderockMountain Volcano, Montana |
| Source | U. S. Geological Survey Professional Paper, Report: P 1602, 19 pp.,1998 |
| ISSN | 1044-9612 |
| GeoRef | 1998-050631 |
| Keywords | absolute age; Ar/Ar; Crazy Mountains Basin; Cretaceous; dates; dikes;fractional crystallization; geochemistry; intrusions; lava flows;lineaments; lithogeochemistry; magmas; magmatism; Mesozoic; mineralcomposition; Montana; Sliderock Mountain; stratovolcanoes; Sweet GrassCounty Montana; tectonic elements; tectonics; United States; UpperCretaceous; USGS; volcaniclastics; volcanism; volcanoes |
Abstract
The Sliderock Mountain stratovolcano, part of the Upper Cretaceouscontinental magmatic arc in southwestern Montana, consists ofvolcaniclastic strata and basaltic andesite lava flows. An intrusivecomplex represents the volcano's solidified magma chamber.Compositional diversity within components of the volcano appears toreflect evolution via about 50 percent fractional crystallizationinvolving clinopyroxene and plagioclase. (super 40) Ar/ (super 39) Arindicate that the volcano was active about 78+ or -1 Ma.
30 samples from this reference
| Sample | Rock name | Major | Trace | Isotope |
|---|---|---|---|---|
| 202112 | Basaltic-andesite | yes | yes | |
| 202114 | Basaltic-andesite | yes | yes | |
| 202115 | Basaltic-andesite | yes | yes | |
| 202116 | Basaltic-andesite | yes | yes | |
| 202124 | Basaltic-andesite | yes | yes | |
| 202125 | Basaltic-andesite | yes | yes | |
| 202091 | Basaltic-andesite | yes | yes | |
| 202092 | Basaltic-andesite | yes | yes | |
| 202093 | Basaltic-andesite | yes | yes | |
| 202100 | Basaltic-andesite | yes | yes | |
| 202119 | Basaltic-andesite | yes | yes | |
| 202120 | Basaltic-andesite | yes | yes | |
| 202095 | Diorite | yes | yes | |
| 202101 | Diorite | yes | yes | |
| 202102 | Diorite | yes | yes | |
| 202105 | Diorite | yes | yes | |
| 202109 | Diorite | yes | yes | |
| 202110 | Diorite | yes | yes | |
| 202113 | Diorite | yes | yes | |
| 202121 | Diorite | yes | yes | |
| 202129 | Diorite | yes | yes | |
| 202088 | Trachyte | yes | yes | |
| 202089 | Trachyte | yes | yes | |
| 202111 | Trachyte | yes | yes | |
| 202126 | Trachyte | yes | yes | |
| 91SR2B | Diorite | |||
| 91SR3 | Andesite | |||
| 91JH38 | Vein | |||
| 91JH36 | Vein | |||
| 202128 | Dacite |