216 Seismology

61 Route 9W - PO Box 1000

Palisades

NY

10964-8000

US

(845) 365-8362

Fax: 

(845) 365-8150

View Website

Plate tectonics is a beautiful unifying theory of geology, and one that answers many questions about the processes that create the earth's surficial variablity, from mountains and volcanoes to rift valleys, shallow seaways and mid-ocean ridges.  However, the theory of plate tectonics poses nearly as many questions as it has answered (of course...this is the way of scientific breakthroughs), particularly regarding the details of how the lithosphere (the brittle outer crust of the earth) deforms during plate collisions.  Deformation styles and mechanisms are controlled by crustal thickness and strength of the rocks, pre-existing structures from earlier episodes of deformation, as well as the stress-field induced by surrounding plate motions.

One way to understand the concept of 'differing styles of deformation' is to look at a mountain belt's large-scale characteristics.  Google Earth is a great way to do this; you can compare, for example, the long, linear, and parallel ridges and valleys of the fold and thrust belt of eastern Pennsylvania and northern NJ, with any of the Laramide uplifts in Wyoming (Bighorn, Wind River, Beartooth-Absaroka) and see how similar compressional stress fields, resulting from plate collisions, can result in dramatically different styles of mountain building (orogens).

My own research is in its early, formational stages, but the theme that so far is holding everything together is the question of how geologic structures control styles of deformation.  One area that I am focusing on is the Basin and Range in the desert southwest of North America, where my advisors Drs. Anders and Christie-Blick have worked for many years.  This area has been undergoing crustal extension and thinning for several million years (beginning around the time my advisors earned their PhD's), and the mountain ranges which have risen up out of the desert between the Sierra Nevada and the Colorado Plateau have been created by a vast network of normal faults which trend generally N-S, roughly orthogonal to the direction of maximum extension.  Andersonian fault mechanics, which seem to accurately describe most of the fault behavior on the earth, predict that normal faults will preferentially form and slip at a 60 degree angle to the surface of the earth. However, many workers have mapped extensional faults which appear to have initiated and slipped at much smaller angles, even 10-15 degrees, a geometry that is much more efficient for crustal extension but unfavorable to our old friend, Gravity.  Fault movement on such 'low-angle' faults requires extenuating circumstances, as far as Anderson would be concerned.  My research is attempting to answer some of the many open questions regarding how, exactly, low-angle faults are related to, and involved in, crustal extension in the Basin and Range.  The tools that I am using are a good, old-fashioned rock hammer, Brunton compass, a pair of dusty boots, plus some new-fangled computer-stuff (GPS, GIS software).

Other research interests of mine are related to Northern Caribbean tectonics, and Norwegian Caledonide tectonics.  I was fortunate to be able to join a NSF-funded rapid response research cruise to Haitian waters in February, following the disastrous January 12 quake of 2010.  I accompanied geophysicists, structural geologists and ocean-bottom sedimentologists from Lamont and several other institutions on a three week cruise, collecting CHIRP sonar, multi-beam bathymetry, and gravity cores from the Canal du Sud near Port-au-Prince.  Further research into this area with Lamont researcher Nano Seeber is in planning stages.