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Lead isotopic compositions and paleohydrology of caldera-related epithermal veins, Lake City, Colorado

Geological Society of America Bulletin

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Abstract

The Uncompahgre caldera, and the Lake City caldera nested within it, each have fossil hydrothermal systems and associated mineral deposits that formed during multiple episodes of mineralization during Oligocene and Miocene time. New lead isotopic analyses for 51 ore samples, mainly galena, combined with previously obtained data for ore minerals and rocks, suggest likely lead source rocks and fluid-migration paths. Hydrothermal flow in the Uncompahgre caldera was predominantly west to east down the topographic slope. Hydrothermal circulation in the Lake City caldera was controlled by local topography and post-caldera intrusions and was isolated from flow in the Uncompahgre caldera and Eureka graben. As in the rest of the San Juan Mountains, lead originally came from a predominantly ~1450 Ma source. Enough variation in 207Pb/204Pb was produced by orogenic events at ca. 1450 Ma, ca. 1760 Ma, and earlier to explain most of the 207Pb/204Pb variation present day in tertiary volcanic rocks and hydrothermal veins. -from Author

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Lead isotopic compositions and paleohydrology of caldera-related epithermal veins, Lake City, Colorado
Series title:
Geological Society of America Bulletin
Volume
104
Issue:
10
Year Published:
1992
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geological Society of America Bulletin
First page:
1236
Last page:
1245
Number of Pages:
10