A talk by Dr Alex Burton-Johnson, British Antarctic Survey.

This talk applies magnetic fabric analyses to understand intrusive magmatic flare-ups in the circum-Pacific continental arc.

Continental arc magmatism is strongly episodic, with voluminous granitic magma addition occurring during discrete high-flux events, but their cause is debated. To understand how the syn-magmatic strain history changes during a flare-up, deformation inferred from granitic magnetic fabrics (Anisotropy of Magnetic Susceptibility, AMS) is compared with geochronological data from the Antarctic Peninsula (Lassiter Coast), Sierra Nevada, and Chile. This indicates a common pattern in orientation and magnitude of syn-magmatic deformation, showing flare-up events occur during periods of increased tectonic compression driven by enhanced interplate coupling and fast subduction. Flare-ups terminate as tectonic compression reduces or the regime becomes extensional, even if convergence rates remain high.

The talk will conclude by comparing this work with early results from our new project applying mineral fabrics to understand the Cretaceous flare-up of Fiordland in New Zealand.

Livestream

This talk will be available to watch live online via Zoom at the link below:

Zoom link for Dr Alex Burton-Johnson's Geology seminar