Title

Outcrop and Grain-Scale Strain analysis of the Tuttle Lake Formation in the Mount Tallac Region; Desolation Wilderness Area, El Dorado County, California

Poster Number

1

Lead Author Major

Geology

Format

Poster Presentation

Faculty Mentor Name

Kurtis Burmeister

Faculty Mentor Department

Earth and Environmental Sciences

Abstract/Artist Statement

Preliminary analysis of the relationship between grain and outcrop-scale fabrics within exposures of the Tuttle Lake Formation in the Mount Tallac region suggests that more strain is accumulated at microscopic scales than previously suspected. Furthermore, the results of our strain analysis suggest the relationship between the magnitude of strain accumulated is proportional to proximity to igneous intrusions. The Tuttle Lake Formation is a thick unit of cross-bedded volcaniclastic breccia and conglomerate that is cut and deformed by numerous igneous intrusions, including at least five different dike sets and a pluton. We conducted detailed, three dimensional fabric analyses on samples from the Tuttle Lake Formation to examine the relationship between strain magnitudes and igneous contacts. Specifically, we prepared three, mutually perpendicular petrographic thin sections from samples collected during the summer 2014 field season. Photomicrographs of these thin sections were then used with the EllipseFit computer program (Vollmer, 2015) to conduct a normalized Fry analysis. The results of our analysis illustrate the magnitude and orientation of strain fabrics within the Tuttle Lake Formation and provide a basis for understanding how these fabrics evolved. An improved understanding of the strain history of the Tuttle Lake Formation will lead to a better understanding of the geologic evolution of the central Sierra Nevada.

Location

DeRosa University Center, Ballroom

Start Date

25-4-2015 2:00 PM

End Date

25-4-2015 4:00 PM

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Apr 25th, 2:00 PM Apr 25th, 4:00 PM

Outcrop and Grain-Scale Strain analysis of the Tuttle Lake Formation in the Mount Tallac Region; Desolation Wilderness Area, El Dorado County, California

DeRosa University Center, Ballroom

Preliminary analysis of the relationship between grain and outcrop-scale fabrics within exposures of the Tuttle Lake Formation in the Mount Tallac region suggests that more strain is accumulated at microscopic scales than previously suspected. Furthermore, the results of our strain analysis suggest the relationship between the magnitude of strain accumulated is proportional to proximity to igneous intrusions. The Tuttle Lake Formation is a thick unit of cross-bedded volcaniclastic breccia and conglomerate that is cut and deformed by numerous igneous intrusions, including at least five different dike sets and a pluton. We conducted detailed, three dimensional fabric analyses on samples from the Tuttle Lake Formation to examine the relationship between strain magnitudes and igneous contacts. Specifically, we prepared three, mutually perpendicular petrographic thin sections from samples collected during the summer 2014 field season. Photomicrographs of these thin sections were then used with the EllipseFit computer program (Vollmer, 2015) to conduct a normalized Fry analysis. The results of our analysis illustrate the magnitude and orientation of strain fabrics within the Tuttle Lake Formation and provide a basis for understanding how these fabrics evolved. An improved understanding of the strain history of the Tuttle Lake Formation will lead to a better understanding of the geologic evolution of the central Sierra Nevada.