Fields of interest:
My primary research interests concern the formation of oceanic crust at the global mid-ocean ridge. I make use of a variety of marine geophysical techniques, including reflection seismic studies to image the interior of oceanic crust and acoustic methods to image the seafloor surface of the crust. One focus of my ridge studies is the extensional failure of newly formed crust. Faulting at mid-ocean ridges is one of the primary relief forming processes that shapes the seafloor. Tectonism plays an important role in determining the subsurface architecture of ridge crest hydrothermal systems and is also one of the key drivers of change in these hydrothermal systems. As crust ages and moves away from the ridge by sea-floor spreading, the faults formed near the axis provide conduits for ongoing low-temperature seawater circulation by which chemical exchange between the oceans and the earth's crust continues for millions of years after crustal creation. My current work involves the application of seismic methods to study the alteration of the crust that occurs as a result of these fluid-rock interactions on the Juan de Fuca plate. I have also used comparative studies of fault parameters and brittle strain at ridges spreading at different rates to better understand the processes governing extensional failure on the ridge crest.
The other focus of my ridge research concerns the origin of the segmentation of mid-ocean ridges. Segmentation is linked to both the pattern of melt delivery from the mantle and the thermal structure of the axial lithosphere, and plays an important role in crustal accretion and subsequent disruption by brittle deformation. My research interests include using reflection seismics to image magma chambers beneath ridges and to characterize the relationship between the magmatic segmentation of the crust defined by these magma bodies and morphological segmentation. In recent work characterizing morphological changes along the ridge, I have found that ridge segmentation may be directly related to plate kinematics, resulting from the migration of the plates over the mantle. From analysis of changes in ridge morphology across large discontinuities of the fast and intermediate spreading ridges we find that the shallow and broad ridge segments are consistently leading in the hotspot reference frame. We attribute these relationships to asymmetric mantle upwelling and melt production beneath migrating ridges, with entrainment of melts generated in the upwelling zone of adjacent segments across discontinuities.
In addition to these mid-ocean ridge studies I am also involved in the application of similar marine geophysical techniques to study sedimentary processes and characterize benthic habitats in the near shore setting. Beginning in 1998 I have been involved in a major collaborative effort with researchers at Lamont, SUNY, CUNY and IES to map the Hudson River estuary. With funding from the New York State DEC, we completed mapping the entire length of the Hudson from the New York Harbor to the Troy Dam in 2004. Our maps of the river bottom reveal a fascinating record of human activities within the Hudson Valley over the past several hundred years. My particular interests in this project are the evolution of the river during the Holocene and the linkages between rising sea-level and climate fluctuations with the changing faunal populations documented in the river sediments.
Some of projects include:
- Marine Geoscience Data Management System ( details )
- Hudson River Benthic Mapping Project ( details )