New Mexico Institute of Mining and Technology
2008-2009 Distinguished Lecturer
Fluid and Heat Circulation in the Subseafloor Ocean

The ocean crust is the largest aquifer on earth, and it hosts vigorous fluid circulation – the entire volume of the world’s oceans cycles through the seafloor in less than 500,000 years.  This fluid circulation plays an important role in redistributing heat within the high permeability ocean crust, and can control the crust’s thermal state by extracting heat.  The thermal state of the crust, in turn, affects diagenetic, metamorphic, and geodynamic processes.  For example, the thermal state of ocean crust is an important control on subduction zone temperatures, which may affect the updip and downdip limits of the megathrust seismogenic zone.  Results from new thermal models that include coupled fluid and heat transport in a subduction zone show that hydrothermal circulation in subducting basaltic basement rocks can greatly suppress temperatures along the subducting slab relative to cases with no fluid transport.  These results are constrained by seafloor heat flux measurements and observations of temperature and fluid pressure in Ocean Drilling Program boreholes.  Fluid circulation in subducting crust may account for previously unexplained thermal anomalies on the Nankai margin of Japan.

Dr. Spinelli has used sediments and borehole observatory data from Ocean Drilling Program sites on the Juan de Fuca Ridge flank, offshore Costa Rica, and the Nankai margin.  He has also served on the Integrated Ocean Drilling Program Science Steering and Evaluation Panel.

August 29, 2008 – University of Missouri-Columbia
October 10, 2008 – University of Wisconsin-Madison
October 17, 2008 – Southern Methodist University
January 28, 2009 – Arizona State University
February 19, 2009 – Bowling Green State University
February 20, 2009 – Indiana University South Bend
March 2, 2009 – University of Wyoming
March 23, 2009 – Utah State University