HR: 0830h
AN: S31E-0815    [PDF]
TI: Pn Tomography at the Intersection of the Rio Grande Rift and Jemez Lineament
AU: * Adams, D D
EM: deradams@nmsu.edu
AF: Department of Geological Sciences, New Mexico State University/MSC 3AB P.O. Box 30001, Las Cruces, NM 88003 United States
AU: West, M
EM: west@nmsu.edu
AF: Physics Department, New Mexico State University/MSC 3D, Las Cruces, NM 88003 United States
AU: Ni, J
EM: jni@nmsu.edu
AF: Physics Department, New Mexico State University/MSC 3D, Las Cruces, NM 88003 United States
AB: Between 1999 and 2001, two separate regional teleseismic studies were carried out in the southwest U.S. The PASSCAL-supported LA RISTRA and CD-ROM projects each included a linear array of several hundred kilometers across or adjacent to the Rio Grande rift. The deployments overlapped by approximately nine months. Earthquakes along the west coast provide Pn raypaths which cross one array and then the other. Inter-array Pn traveltimes are inverted for a map of Pn velocity. The synthesis of these data provides a unique opportunity to probe the state of the mantle beneath the central and northern Rio Grande rift. The Rio Grande rift extends from central Colorado into southern New Mexico. The rift has been spreading intermittently since about 36 Ma and has been accompanied by several types of volcanism. In the past 5 Myr most volcanism in the region has occurred along a northeast-trending lineation referred to as the Jemez Lineament. The inter-array Pn raypaths serendipitously cover the intersection of the Jemez lineament and the Rio Grande rift, allowing us to explore the relationship between these two features which dominate the tectonics of the southwest. In particular we seek an explanation which unifies the two features and identifies the cause of volcanism along the Jemez Lineament.
DE: 7218 Lithosphere and upper mantle
DE: 8109 Continental tectonics--extensional (0905)
DE: 8180 Tomography
SC: Seismology [S]
MN: 2003 Fall Meeting