This project provides funds for a two-year renewal of the St. Elias Erosion-tectonics Project (STEEP). STEEP is a 9 institution, multidisciplinary study of the St. Elias orogen in southern Alaska that involves researchers examining the system from the outcrop to lithosphere scale. To date, STEEP has produced 17 papers with another 9 submitted or nearing submission, sponsored 71 abstracts, will have matriculated 5 masters and 4 Doctoral students by Spring 2010, and fundamentally changed our understanding of Alaskan tectonics and the interaction of tectonics and climate in mountain building. The renewal funds will be used for: 1) final processing and interpretation of some key datasets that were not acquired until year 5 of the project including the marine seismic survey (ship delays) and reoccupation of key GPS sites (weather problems in 2008); and 2) a complete integration of results which was not possible until now due to these delays. A complete integration and synthesis of these superb datasets has the potential to be transformative in our understanding of how crustal structure and tectonic forces interact with Earth surface processes of glacial erosion and sedimentary transport to grow a mountain range and a massive continental shelf.
Southern Alaska contains a rich record of upper and lower plate processes related to active subduction of a flat slab. Shallow subduction of thick oceanic crust along this convergent margin has prompted crustal shortening, exhumation, inversion of sedimentary basins, and cessation of magmatism above the area of ongoing flat slab subduction. Surface uplift and erosion above the flat slab region results in deposition of thick, Neogene clastic wedges in sedimentary basins located along the western, northern, and southern perimeters of the flat-slab region. Along the eastern perimeter, northwestward-propagating Oligocene–Quaternary slab-edge volcanism and transtensional basin development along dextral strike-slip faults record northwestward insertion of a shallow slab against the curved continental margin of eastern Alaska. Collectively, integration of geological and geophysical data indicates that Cenozoic flat slab subduction has had a direct role in the regional tectonic configuration of the southern Alaska convergent margin. This grant also included an educational outreach field trip that allowed Native American high school students the opportunity to put their hands on an active fault, discuss the role of earth science in natural hazard decision making and on their local communities, and to meet Native American graduate students that might serve as mentors or role models. We have found that when Native students realize that through science and engineering that they can assist and work directly with their home communities, then they are much more interested in these subject areas.
