Masters Theses
Abstract
"The Wallamatogus Pluton, Maine, exhibits systematic variation in grain size, mineralogy, and phenocryst abundance (alkali-feldspar) from the margin to the center of the pluton. Three facies are recognized: 1) outermost, seriate, coarse-grained (Owe), 2) porphyritic medium- to fine-grained (Dwp ), 3) innermost, fine-grained equigranular (Dwf). These facies are concentrically arranged and their contacts are gradational. Muscovite and biotite occur in all facies; the outer two facies contain garnet, and tourmaline. Muscovite and biotite grains within micaceous enclaves compositionally overlap primary muscovite, suggesting that they are early-crystallized accumulations. Muscovite in multiphase clusters and secondary muscovite compositionally overlap, suggesting formation during post-crystallization alteration. High strain zones occur locally in the pluton. Mica and plagioclase grains are kinked; garnet and feldspar grains fractured and separated; quartz is recrystallized and commonly fills cracks in feldspar. Deformed garnet grains have high Ca contents compared to those within micaceous enclaves and those exhibiting magmatic equilibrium indicating re-equilibration during subsequent deformation.
Temperature estimates for magmatic crystallization, and for deformation, are constrained from combined petrographic analyses and garnet-biotite geothermometry. Early crystallizing garnets record liquidus temperatures of ~800°C, whereas the composition of garnet rims yield near solidus temperatures of ~600°C. Deformed garnets record temperatures of 400 to 450°C. These results better constrain the geologic history of the Wallamatogus Pluton and also, the terrane in which it intruded"--Abstract, p. iii
Advisor(s)
John P. Hogan
Committee Member(s)
David Wronkiewicz
F. Scott Miller
Department(s)
Geosciences and Geological and Petroleum Engineering
Degree Name
M.S. in Geology and Geophysics
Publisher
University of Missouri--Rolla
Publication Date
Spring 2001
Pagination
x, 175 pages
Note about bibliography
Includes bibliographical references (pages 172-174)
Rights
© 2001 Joy Kathleen Drake, All rights reserved.
Document Type
Thesis - Open Access
File Type
text
Language
English
Thesis Number
T 7907
Print OCLC #
47769681
Recommended Citation
Drake, Joy Kathleen, "Constraining the crystallization and post-crystallization history of the Wallamatogus Pluton, Maine, using compositional data from garnet, biotite and muscovite" (2001). Masters Theses. 2033.
https://scholarsmine.mst.edu/masters_theses/2033