Deep Structure of Magmatic Arcs

An abiding interest of mine is the deep structure of magmatic arcs -- especially island arcs.

Costa Rican Magmatic Arc

Our group has undertaken a large reflection/refraction seismic study of the magmatic arc in Costa Rica.

To see a map of the offshore data collection, conducted in Feb-April 2008, click on the thumbnail below:

Offshore Campaign Map, 2008

Offshore Campaign Map, 2008

The first two cruises of the R/V Langseth.


Our work was covered in an article (in Spanish) in La Nacion, Costa Rica's national newspaper.  You can also see the web version (more pictures) here.

Aleutian Arc

The Aleutian island arc is a terrific place to study the processes that create arc crust, due to its relatively simple tectonic setting.  

I first got involved in studying the orign of arc crust through a 1994 marine seismic survey I participated in while I still was at WHOI, together with a number of other PI's (Sue McGeary, John Diebold, Nathan Bangs, and Simon Klemperer).  The survey consisted of seismic reflection data acquired by the R/V Ewing and wide-angle seismic data acquired on ocean-bottom seismic instruments (which our group deployed from the R/V Alpha Helix) and land instruments on the islands deployed by the Stanford group.

1999 Geology paper

This paper showed results from one of the cross-arc lines in the Aleutians (A1), based on reflection and OBS data (Fig. 1 at right).  The results showed that the average velocity structure of the arc on Line A1 was too fast to represent a bulk andesitic composition and was significantly faster (and thus more mafic) than mature continental crust (Fig. 2 at right). 

You can download a PDF of the paper here.

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Or call me at work:  307-766-2427
(But email is better.)