29 September, 2015

This paper revised the geological history of the Antarctic Peninsula to show how it developed over the last 500 million years, and used this history to tell us about the global process of how the continental crust itself grows.

The Earth is unique in our solar system in that it has two types of crust: oceanic and continental. Whilst oceanic crust is transient, being constantly formed and destroyed (the oldest being ~270 million years old), the lighter density of the continental crust makes it much harder to destroy and so during the history of our planet the continents have continued to grow. This provides us with the landmasses that we live on and also concentrates most of the world’s economic mineral wealth.

However, the processes by which these continents grow remain in dispute. The two dominant opposing arguments are: (1) through the formation of offshore volcanic islands (similar to Indonesia) that later collide with the edge of a continent in successive collisions of new crust; or (2) through the growth of the continents in situ through extraction of lava from the mantle beneath the crust and emplacement of this new material directly in to the continent’s margin.

In this paper we argue against the existing model for the growth of the Antarctic Peninsula continental crust through the collision of Antarctica with an offshore volcanic island chain. Instead we review and analyse all of the existing data to show how the region developed through a series of distinct events emplacing new magmatic rocks and depositing new sedimentary rocks directly on to and within the Peninsula.

Through each of these events we are able to present a new history of the region, showing how the 1,300km long Antarctic Peninsula developed, since its earliest rocks about 500 million years ago to the recent volcanics that continue to mark its growth. This evidence by which this revised history was derived are not unique for the Antarctic Peninsula, and so finally we compare our findings with the geology of South America, North America and New Zealand to show how the geology of the Antarctic continent continues to shed new light on global processes and our understanding of our planet’s history.


The Paper
Autochthonous vs. accreted terrane development of continental margins: a revised in situ tectonic history of the Antarctic Peninsula

Burton-Johnson & T. R. Riley

Published by
Journal of the Geological Society. 10.1144/jgs2014-110