| 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 |
| Genre: | Article |
| ProdID: | 70016893 |
| Citation Author: | Sanford, R. F. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | 1245 |
| Citation Issue: | 10 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Geological Society of America Bulletin |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | 10 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Lead isotopic compositions and paleohydrology of caldera-related epithermal veins, Lake City, Colorado; 1992; Article; Journal; Geological Society of America Bulletin; Sanford, R. F. |
| Citation Start Page: | 1236 |
| Citation Volume: | 104 |
| Citation Year: | 1992 |
| Type: | citation/reference |
| Text: | Lead isotopic compositions and paleohydrology of caldera-related epithermal veins, Lake City, Colorado; 1992; Article; Journal; Geological Society of America Bulletin; Sanford, R. F. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1992 00:00 -0600 |
| Publisher: | |
