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The Mount Evans batholith in the Colorado Front Range: revision of its age and reinterpretation of its structure

Geological Society of America Bulletin

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Abstract

The Mount Evans batholith is composed of a main phase of massive to conspicuously foliated monzogranite and granodiorite and undeformed aplite and pegmatite. The Mount Evans batholith was previously considered to be part of the 1.7 Ga Routt Plutonic Suite. New U-Pb zircon ages on four samples (granodiorite, monzogranite, and granite), however, indicate that the batholith was emplaced at 1442 ?? 2 Ma and belongs to the Berthoud Plutonic Suite. Most of the batholith has igneous textures and structures, except in the vicinity of the Idaho Springs-Ralston shear zone where those features are tectonically recrystallized and foliated. The Mount Evans batholith is anomalous in composition and structure compared to most other 1.4 Ga plutons of the southwestern US. The differences probably reflect different sources of partial melting; the specific tectonic setting where rocks of such disparate origin are temporally and spatially juxtaposed is not understood. -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The Mount Evans batholith in the Colorado Front Range: revision of its age and reinterpretation of its structure
Series title:
Geological Society of America Bulletin
Volume
105
Issue:
6
Year Published:
1993
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
791
Last page:
806
Number of Pages:
16