Chapter 3.2a Bransfield Strait and James Ross Island: volcanology

Abstract

Following more than 25 years of exploration and research since the last regional appraisal, the number of known subaerially exposed volcanoes in the northern Antarctic Peninsula region has more than trebled, from less than 15 to more than 50, and that total must be increased at least three-fold if seamounts in Bransfield Strait are included. Several volcanoes remain unvisited and there are relatively few detailed studies. The region includes Deception Island, the most prolific active volcano in Antarctica, and Mount Haddington, the largest volcano in Antarctica. The tectonic environment of the volcanism is more variable than elsewhere in Antarctica. Most of the volcanism is related to subduction. It includes very young ensialic marginal basin volcanism (Bransfield Strait), back-arc alkaline volcanism (James Ross Island Volcanic Group) and slab-window-related volcanism (seamount offshore of Anvers Island), as well as volcanism of uncertain origin (Anvers and Brabant islands; small volcanic centres on Livingston and Greenwich islands). Only ‘normal’ arc volcanism is not clearly represented, possibly because active subduction virtually ceased at c. 4 Ma. The eruptive environment for the volcanism varied between subglacial, marine and subaerial but a subglacial setting is prominent, particularly in the James Ross Island Volcanic Group.

Back‐Arc Extension of the Central Bransfield Basin Induced by Ridge–Trench Collision: Implications From Ambient Noise Tomography and Stress Field Inversion

“…The present trench, that once extended along the entire Pacific margin of the AP throughout the Mesozoic (Birkenmajer, 1994; Leat & Riley, 2021), is the remnant subduction site that was progressively eliminated from southwest to northeast during a series of ridge–trench collisions (Eagles & Jokat, 2014; Larter & Barker, 1991; Livermore et al., 2000). The Bransfield Basin has suffered extension since ∼4 Ma (Larter & Barker, 1991; Smellie, 2021), synchronously with the latest ridge–trench collision at the southwest of the Hero Fracture Zone (Larter & Barker, 1991; Lodolo & Pérez, 2015). As a young back‐arc basin formed in a long‐term subduction setting, the Bransfield Basin is an ideal site to learn how the back‐arc extension initiates and what is the driving mechanism behind its evolution.…”

Introduction to volcanism in Antarctica: 200 million years of subduction, rifting and continental break-up

“…Coincidentally, from c. 12 Ma an extensive back-arc mafic alkaline volcanic field developed to the rear of Graham Land in the James Ross Island region (Fig. 1f) (Haase and Beier 2021;Smellie 2021b). It is dominated by the very large shield volcano of Mount Haddington, which is predominantly glaciovolcanic and contains an unrivalled record of the Antarctic Peninsula Ice Sheet (Smellie et al 2008).…”

“…The magmatic activity shut down progressively in a clockwise direction, commencing in Marie Byrd Land in the mid-Cretaceous (Larter et al 2002). Subduction is active today (at a very slow rate) only at the northern tip of the Antarctic Peninsula, where a small ensialic marginal basin populated with numerous submarine volcanic centres opened up in response to plate boundary forces, including slab rollback (Haase and Beier 2021;Smellie 2021b). The marginal basin includes Deception Island, one of Antarctica's most active volcanoes (Geyer et al 2021), which underwent a major caldera collapse eruption c. 4 kyr ago that dispersed ash more than 4000 km in an arcuate swathe across the Scotia Sea and much of East Antarctica (Antoniades et al 2018).…”

Characterizing the Geomagnetic Field at High Southern Latitudes: Evidence From the Antarctic Peninsula

“…Volcanic rocks of the area comprise the JRIVG, and consist of hundreds of basalt flows, scoria cones, stocks, dikes, plugs, sills, and hyaloclastite foresets. Eruptive products were variably subaerial, subaqueous, and subglacially emplaced (Smellie, 2021b). Mt.…”

“…However, given the alteration that we observe in our samples during the experiments, such a method is not appropriate to apply to this data set. S1 in Supporting Information S1 for additional age information, see Smellie (2021b) for a compilation of ages from the JRIVG and associated references. b Transitional poles determined by Vandamme (1994) cutoff angle.…”