Origin and Diagenesis of Lacustrine Sediments of the Late Oligocene Creede Formation, Southwestern Colorado

Vertically-zoned sequences of authigenic silicates in tuffs reflect alteration of silicic-intermediate vitric tuff within an elevated geothermal gradient (90$\sp\circ$-150$\sp\circ$C/km). The abundance of clinoptilolite - Al-smectite in drillcore CCM-2 is consistent with diagenetic waters having low to moderate salinity and a pH of 7-9. The higher-grade mineral assemblage (analcime, K-feldspar, quartz, interstratified illite/smectite and chlorite/smectite in CCM-1) is due to hotter fluids migrating through the more permeable strata. Alteration occurred in a relatively closed system. On the basis of studies of zeolite formation in other burial diagenetic systems, the observed authigenic silicate assemblage in tuffs of the Creede Formation must have formed within $\sim$3-4 m.y. of deposition.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Geology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Finkelstein, David Barry

Contributors dc:contributor

• Altaner, Stephen P.

• Geology

Language dc:language

eng

Identifier

(MiAaPQ)AAI9812586

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/86547