Modulation of deformation by magmatic tempo, Coast Mountains Batholith, British Columbia, Canada

The data is used to constrain the tectonmagmatic evolution of the southern Coast Mountains batholith from ca. 120 – 50 Ma.  Three periods of deformation coincide spatially and temporally with three periods of high-flux magmatism derived from mantle sources.  These results suggest that the deformation was modulated by episodic magmatism and so was not a driver of episodic magmatism.  During a period of high-flux magmatism, deformation style within the active arc reflects coeval relative plate motions; the timing of shifts in plate motions outside of these periods may not be recorded by the deformation.

Methods
Data were collected and analyzed through integrated field and laboratory work by the principal investigators and their students as more fully described in Rusmore et al., 2024. DOI:10.1029/2024TC008318 (open access).  Field work was conducted in the southern Coast Mountains of British Columbia on a NE-trending transect along Bute and Knight Inlets and in the region around Mount Waddington in 2014, 2015, and 2016.  Analysis of structural, petrographic, and field data was conducted at Occidental College. The U-Pb geochronology was performed at the University of Arizona LaserChron Center (ALC); Ar geochronology was conducted at Stanford University.  Microprobe analysis used in hornblende geothermobarometry was conducted at the California Institute of Technology, Earth and Planetary Sciences division.