Abstract: Geometry, Spatial Distribution and Scaling Relationships of Faults in Oblique Rift Zones
CLIFTON, AMY E.
I propose to examine fault populations in oblique rift zones to determine how fault geometry, distribution and scaling relationships change as the angle (alpha) between the rift zone and the extension direction changes. Present understanding of fault populations comes mainly from studies in which the rift zone is orthogonal to the extension direction. However, a large number of rift basins are oriented at an angle to that direction. Scaled clay models analyzed by Withjack and Jamison (1986) will be reexamined in light of recent developments in the characterization of fault populations. Photographs of the model surfaces will be scanned and digitally enhanced, then used to determine the spatial distribution and size distribution of fault lengths as a function of alpha. Faults will first be grouped together, then separated into sub-populations based on strike to see which method best characterizes the population. Predictions based on clay modeling results will be tested against field data from the Minas subbasin of the Fundy basin, Nova Scotia, and the Hartford subbasin in Connecticut, which have angles of 45 degrees and 75 degrees respectively, and from the Reykjanes Peninsula of Iceland, which has an alpha angle of 28 degrees. It is hoped that the combined use of the clay models and field data can provide a better characterization of the nature of faulting in oblique rift zones, including the interconnectedness of faults of different orientation. This information can be useful to the oil industry because these fractures provide both barriers and pathways for fluid migration.
AAPG Search and Discovery Article #90940©1997 AAPG Foundation Grants-in-Aid