| Title | Denudation and deformation in a glaciated orogenic wedge; the St. Elias Orogen, Alaska |
| Author | Berger, A.L.; Spotila, J.A. |
| Author Affil | Berger, A.L., Virginia Polytechnic Institute and State University, Department of Geosciences, Blacksburg, VA |
| Source | Geology (Boulder), 36(7), p.523-526, . Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091- 7613 |
| Publication Date | July 2008 |
| Notes | In English. With GSA Data Repository Item 2008129. 31 refs. GeoRef Acc. No: 284857 |
| Index Terms | radioactive age determination; age determination; radioactive age determination; cooling; deformation; erosion; glacial erosion; glaciation; tectonics; United States- -Alaska--Southern Alaska; (U-Th)/He; absolute age; Alaska; apatite; Cenozoic; dates; denudation; erosion rates; exhumation; glaciated terrains; orogenic belts; orogeny; phosphates; Quaternary; Saint Elias Orogeny; Southern Alaska; tectonic wedges; United States |
| Abstract | Apatite (U-Th)/He dating from the St. Elias orogen in southern Alaska illustrates a potential association between long-term denudation and glacier sliding. Cooling ages as young as 0.4 Ma (exhumation approximately 4-5 mm/yr) are concentrated in a narrow band near the glacier equilibrium line altitude (ELA) front, where mean Quaternary ELA intersects the windward flank of the orogen. This band of denudation is not correlated with individual faults, structural trends, or known concentrations of precipitation, and we propose that it is produced by focused glacier sliding at or near the ELA front. This implies that long-term glacial erosion is a maximum at ELA, which corroborates model predictions that glaciers and climate can control the pattern of crust removal from orogens. Denudation rates do not covary with fluctuations in glacier size along the ELA front, suggesting that small glaciers are capable of keeping pace with incision by larger ones and tectonic rock uplift. Ice discharge may thus play a critical, but complex, role in excavating glaciated orogens. |
| URL | http://hdl.handle.net/10.1130/G24883A.1 |
| Publication Type | journal article |
| Record ID | 62005218 |