Paleomagnetic and Structural Analysis of the Western Margin of the Rio Grande Rift, San Luis Basin: Implication for the Kinematic Evolution of Continental Rift Zones

Stephanie Mason
University of New Mexico, Department of Earth and Planetary Sciences Albuquerque, NM
[email protected]

The Rio Grande rift is a late Cenozoic continental rift extending from central Colorado to southern New Mexico. Hanging wall margins of the Rio Grande rift typically contain en echelon normal fault systems with intervening rock masses that define areas of complex structure, called relay zones. Relay zones transfer displacement through complex strain and eventual linkage of the faults and hold critical clues to understanding the initiation and growth of fault zones.

The evolution of Rio Grande rift fault linkage will be investigated through a detailed structural and paleomagnetic analysis of the western margin of the San Luis basin, Colorado. The margins of the rift contain exposures of laterally continuous Eocene-Oligocene ignimbrites and well-preserved rift structures that will be sampled for paleomagnetic data to assess vertical-axis rotations, signifying fault displacement and interaction. Vertical-axis rotations over discrete time periods, and the timing and kinematics of fault linkage in the western margin, will be determined to develop a comprehensive picture of the evolution of the western San Luis basin margin.

This study will provide a more complete picture of the extensional evolution of a continental rift margin and will add to the understanding of temporal and spatial patterns of deformation in rift zones. The results will be of importance for understanding seismic hazards and the possible structural controls on the occurrence of hydrocarbons and aquifers in and near rift zones.

AAPG Search and Discovery Article #90094 © 2009 AAPG Foundation Grants in Aid