Miocene-Recent post-subduction alkaline magmatism along the Antarctic Peninsula II. Petrology

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Scattered occurrences of Miocene-Recent volcanic rocks of the alkaline intraplate association represent one of the last expressions of magmatism along the Antarctic Peninsula. The volcanic rocks were erupted after the cessation of subduction which stopped following a series of northward-younging ridge-crest‒trench collisions. Volcanism has been linked to the development of a growing slab window beneath the extinct convergent margin. Geochemically, lavas range from olivine tholeiite through to basanite and tephrite. Previous studies have emphasized the slab window tectonic setting as key to allowing melting of peridotite in the asthenospheric void caused by the passage of the slab beneath the locus of volcanism. This hypothesis is revisited in the light of more recent petrological research, and an origin from melting of subducted slab-hosted pyroxenite is considered here to be a more viable alternative for their petrogenesis. Because of the simple geometry of ridge subduction, and the well-established chronology of ridge-crest-trench collisions, the Antarctic Peninsula remains a key region for understanding the transition from active to passive margin resulting from cessation of subduction. However, there are still some key issues relating to their tectono-magmatic association, and principally, the poor geochronological control on the volcanic rocks requires urgent attention.
Original languageEnglish
Title of host publicationVolcanism in Antarctica
Subtitle of host publication200 Million Years of Subduction, Rifting and Continental Break-Up
PublisherGeological Society of London
Publication statusAccepted/In press - 30 Nov 2018

Publication series

NameGeological Society Memoir

Bibliographical note

Investigations into alkali basalts in the Antarctic Peninsula were made when MJH was an employee of the British Antarctic Survey. The number of people who made the fieldwork possible are too numerous to mention, but to anyone involved in the 1983-84, 85-86 and 87-88 Austral Summer field seasons, I owe a debt of gratitude. The manuscript was improved by the thoughtful reviews of Kurt Panter and John Gamble. The late Peter Barker first introduced me to the complexities of ridge-crest trench interactions and for that I will also be grateful.


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