The Jackson School of Geosciences has funded a research initiative in the new research area and discipline of structural diagenesis. Structural diagenesis, as described by Steve Laubach and Kitty Milliken in the keynote address at the AAPG Hedberg Research Conference on this topic in February 2004, is an approach that deliberately synthesizes mechanics and geochemistry in ways that have been neglected in traditional diagenesis and structural studies. This approach promises to provide solutions to long-standing geologic problems in sedimentary basins, as the iteration of mechanical and chemical processes lead to feedback and strongly nonlinear processes. The program is designed to make the Jackson School a world leader in linked structural and diagenetic issues. This effort will make previous approaches to diagenesis and mechanical studies in sedimentary basins obsolete.

The initial study under this initiative is on fracture-opening processes from the perspective of chemical/mechanical evolution of fracture systems. Fluid flow in fractured rock is an increasingly central issue in recovering water and hydrocarbon supplies and geothermal energy in predicting flow of pollutants underground, in engineering structures, and in understanding large-scale crustal behavior. The goal of this project is to develop an understanding of how fracture growth and diagenetic alteration interact to systematically create and destroy fracture porosity. This cross-disciplinary research will result in fundamental advances in our understanding of how diversity of natural fracture patterns evolves and better predictions of fracture-pattern attributes in the subsurface where sparse sampling is the rule. Jackson School support will help build our already strong cross-disciplinary and cross-departmental program in fundamental and applied fracture and rock-property evolution research. As an essential step in a broad study of links between mechanical and chemical processes in opening fractures, we are testing a new theory of cementation in fractures that predicts fracture porosity evolution as a function of temperature, surface area, and opening history. Results will allow us to estimate fracture-opening rates, which will be a significant contribution to understanding crustal mechanics and a constraint on intraplate tectonic processes.