Masters Thesis Defense - Dylan McKeen - HSH 336
(2:30 pm)
Dylan McKeen will be defending his Thesis on Monday April 13th at 2:30pm in Huggins 336.
https://www2.acadiau.ca/graduate/graduate-studies-newsreader/thesis-defence-dylan-mckeen.html
Origin, terrane affinity, tectonic evolution, and age of the Clyburn Brook Formation, Cape Breton Highlands, Nova Scotia, Canada
Thesis Committee:
Dr. Deanne van Rooyen, Supervisor
Dr. Brendan Murphy, St. FX., External Examiner
Dr. Rob Raeside, Internal Examiner
Dr. A. Dawn Ryan, Chair of the defence
Abstract
The Eastern Highlands Shear Zone (EHSZ) in the Cape Breton Highlands of Nova Scotia juxtaposes the Ganderian Aspy terrane consisting primarily of Ordovician to Silurian metavolcanic and metasedimentary rocks and abundant mid-Paleozoic granitoid plutons with the Ganderian Bras d’Or terrane consisting primarily of Ediacaran metasedimentary rocks and Ediacaran to Cambrian plutons. The Clyburn Brook Formation (CBF) is an assemblage of interlayered, low-grade metasedimentary and bimodal metavolcanic rocks which straddles the northeastern part of the EHSZ. Based on field relationships and petrography, the CBF is divided into six members. New maximum depositional ages of ~420 Ma and ~410 Ma in the lower and upper epiclastic members, respectively, and a new igneous crystallization age of 395.8 ± 2.2 Ma for felsic meta-tuff in the middle volcanic member suggest that the CBF post-dated initial convergence along the EHSS and formed in an early Devonian syn-convergent pull-apart basin that received detritus from both the Aspy and Bras d’Or terranes. The volcanic rocks in the CBF are younger than the arc-related volcanic activity at 430 to 420 Ma that is well-documented elsewhere in the Aspy terrane. The CBF was intruded by the largely undeformed Cameron Brook granodiorite (CBG) dated previously at 402 ± 3 Ma. Based on similar age and close association, the volcanic rocks of the CBF are interpreted to be comagmatic with the Cameron Brook granodiorite and together they represent mid-Devonian magmatism during the later stages of terrane juxtaposition. The CBF records syn-convergent deformation and folding, as well as post-collisional brittle deformation, resulting from transpressional deformation during protracted convergence of the Aspy and Bras d’Or terranes. Based on lithological, age and geochemistry, the CBF is considered part of the Aspy terrane, and the surface boundary between those terranes follows the southern margin of the CBF and Cameron Brook pluton.
