Potassium-argon ages bearing on the igneous and tectonic history of the Elk Mountains and vicinity, Colorado: A preliminary report

Geological Society of America Bulletin
By: , and 

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Abstract

K-Ar ages for epizonal plutonic rocks together with field studies indicate that uplift of the Sawatch Range began at least 72 m.y. ago. Vertical uplift of the Sawatch Range was followed or accompanied by gravity sliding of sedimentary rocks along the Elk Range thrust fault. The greatest volume of exposed intrusive rocks in the Elk Mountains, Ruby Range, and West Elk Mountains consists of granodioritic rocks of Oligocene age which are younger than the Elk Range thrust. Miocene and Pliocene(?) mafic dikes were emplaced after most of the structural features in the area had developed. The Treasure Mountain dome near Marble was formed by emplacement of a unique soda granite pluton about 12.5 m.y. ago.

Discordant K-Ar and Rb-Sr ages for biotite from the Twin Lakes stock in the Sawatch Range suggest that this large pluton is of Late Cretaceous or early Tertiary age and lost argon during Oligocene plutonism, or is of Eocene age and represents a separate event not yet supported by other radiometric dates from the area.

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Publication type Article
Publication Subtype Journal Article
Title Potassium-argon ages bearing on the igneous and tectonic history of the Elk Mountains and vicinity, Colorado: A preliminary report
Series title Geological Society of America Bulletin
DOI 10.1130/0016-7606(1969)80[1749:PABOTI]2.0.CO;2
Volume 80
Issue 9
Year Published 1969
Language English
Publisher Geological Society of America
Description 9 p.
First page 1749
Last page 1756
Country United States
State Colorado
City Marble
Other Geospatial Elk Mountains, Ruby Range, Sawatch Range, Treasure Mountain, Twin Lakes, West Elk Mountains
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