Record Details
Fold growth due to kink-band migration in repeated earthquakes, Sierra de Villicum, San Juan, Argentina
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Fold growth due to kink-band migration in repeated earthquakes, Sierra de Villicum, San Juan, Argentina |
| Names |
Krugh, William C.
(creator) Meigs, Andrew (advisor) |
| Date Issued | 2003-06-18 (iso8601) |
| Note | Graduation date: 2004 |
| Abstract | Growth strata geometries and deformed geomorphic surfaces reflect the shorttimescale growth of Sierra de Villicum (San Juan Province, Argentina). Accumulated deformation in repeated earthquakes is recorded by the structural geometry of deformed geomorphic surfaces. Through geologic mapping and topographic surveying, six strath terraces were identified on the eastern flank of Sierra de Villicum. A comparison between the modem channel and long terrace profiles indicates that recent deformation is restricted to the eastern half of the study area. In this region, the terrace surfaces are folded - 15° from their original orientation with the fold axes of younger terraces located progressively to the east. This folding has created stepped topography that is interpreted to reflect eastward migration of an active axial surface through repeated earthquakes. Ages for the terrace surfaces were obtained through physical correlation with similar surfaces to the south of the study area. These surfaces are dated at 18700, 6800, and 1500 yr BP using cosmogenic radionuclide exposure age dating (Siame et al., 2002) Deformation rates were calculated by measuring the displacement between the preserved growth axial surface and the active axial surface for each terrace level. On the basis of the inferred terrace ages, the measured axial surface positions yields average vertical displacement rates of 1.25±0.3 mm/yr and average horizontal displacement rates of 4.6±1.0 mm/yr. The close correlation between historically documented deformation and measured fold displacements suggests the discovery of new evidence for fold growth during a devastating Ms. 7.4 earthquake in 1944. |
| Genre | Thesis |
| Topic | Sierra de Villicum (Argentina) |
| Identifier | http://hdl.handle.net/1957/9018 |
