GLS Seminar: Dr. Robert Lowell, "Mathematical Models of Ridge Crest Hydrothermal Systems: From the Basic to the Complex"

Friday, September 29th, 2006 from 3:30 PM – 4:30 PM, 4069 Derring Hall

Refreshments will be served at 4:30 PM. The public is cordially invited.

Mathematical Models of Ridge Crest Hydrothermal Systems: From the Basic to the Complex

Robert Lowell, Virginia Polytechnic Institute and State University

Hydrothermal processes at ocean ridge crests involve a complex interplay between the dynamics of heat supply and the evolution of crustal permeability that results in a broad spectrum of issues to challenge hydrothermal modelers. Among these are: (1) the detailed relationships between heat supply and hydrothermal heat transfer, (2) the mechanisms controlling vent stability and long-term evolution of hydrothermal vents, including the relationship between focused and diffuse flow, (3) temporal variability related to magmatic and tectonic events, (4) boiling, phase separation and the evolution of vent chlorinity, and (5) the linkages among heat transfer, fluid flow, geochemical and biological processes in controlling character and evolution of vent fields. I will discuss the “single-pass model” approach to show that the basic state of a black smoker vent field requires a conductive boundary layer no more than a few tens of meter thick above a magma chamber and a discharge zone with permeability between 10^-13 and 10^-11 m². Long-term vent stability requires that the thin conductive boundary be maintained, by some combination of magma replenishment and crack propagation, which may be associated with dike emplacement. A broad recharge zone is needed to prevent clogging by anhydrite. The dynamic relationships between focused and diffuse ridge-axis venting and the response of systems to tectonic events require complex interactions between circulation in pillows and dikes. Since nearly all high temperature systems exhibit phase separation, the development of multiphase flow and reactive transport models is necessary for further advancement.