Document Type
Honors Thesis
Major
Earth Sciences, Physics
Advisor(s)
Scott Johnson
Committee Members
Peter Koons, Daniel Lux, Samuel Hess, Robert Brinkley
Graduation Year
August 2008
Publication Date
Fall 12-2023
Abstract
Crystallographic and shape preferred orientation (SPO) fabrics that develop in mylonitic shear zones can preserve the mean kinematic vorticity number (Wm) of bulk flow. Microstructural methods exploiting dynamically recrystallized quartz and porphyroclast SPO fabrics typically yield conflicting values of Wm. The Sandhill Corner Mylonite Zone of the Norumbega Fault System, Maine, USA, serves as a case study for investigating this discrepancy; Wm estimates range from 0.90 to 1.00 employing the former method (Method 1) and from 0.3 to 0.6 employing the latter method (Method 2). Using a numerical model, I show how a low-viscosity layer (LVL) surrounding clasts affects their SPO and makes Method 2 underestimate Wm. I propose a method based on my modeling results for estimating the viscosity contrastη~ between the LVL and rock matrix in natural examples.
Recommended Citation
Lenferink, Hendrik, "Kinematic Vorticity and Porphyroclast Rotation in Mylonites of the Norumbega Fault System: Implications for Paleoviscometry" (2023). Honors College. 842.
https://digitalcommons.library.umaine.edu/honors/842