Mid-Pleistocene Climate Transition Drives Net Mass Loss From Rapidly Uplifting St. Elias Mountains, Alaska
- ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
- Ellen A. Cowan Ph.D, Professor (Creator)
- Institution
- Appalachian State University (ASU )
- Web Site: https://library.appstate.edu/
Abstract: Erosion, sediment production, and routing on a tectonically active continental margin reflect both tectonic and climatic processes; partitioning the relative importance of these processes remains controversial. Gulf of Alaska contains a preserved sedimentary record of the Yakutat Terrane collision with North America. Because tectonic convergence in the coastal St. Elias orogen has been roughly constant for variations in its eroded sediments preserved in the offshore Surveyor Fan constrain a budget of tectonic material influx, erosion, and sediment output. Seismically imaged sediment volumes calibrated with chronologies derived from Integrated Ocean Drilling Program boreholes show that erosion accelerated in response to Northern Hemisphere glacial intensification ( 2.7 Ma) and that the 900-km-long Surveyor Channel inception appears to correlate with this event. However, tectonic influx exceeded integrated sediment efflux over the interval 2.8–1.2 Ma. Volumetric erosion accelerated following the onset of quasi-periodic ( 100-ky) glacial cycles in the mid-Pleistocene climate transition (1.2–0.7 Ma). Since then, erosion and transport of material out of the orogen has outpaced tectonic influx by 50–80%. Such a rapid net mass loss explains apparent in- creases in exhumation rates inferred onshore from exposure dates and mapped out-of-sequence fault patterns. The 1.2-My mass budget imbalance must relax back toward equilibrium in balance with tectonic influx over the timescale of orogenic wedge response (millions of years). The St. Elias Range provides a key example of how active orogenic systems respond to transient mass fluxes, and of the possible influence of climate-driven erosive processes that diverge from equilibrium on the million-year scale.
Mid-Pleistocene Climate Transition Drives Net Mass Loss From Rapidly Uplifting St. Elias Mountains, Alaska
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Additional Information
- Publication
- Ellen Cowan, Sean P. S. Gulick, John M. Jaeger, Alan C. Mix, Hirofumi Asahi, Heinrich Bahlburg, Christina L. Belanger, Glaucia B. B. Berbel, Laurel Childress, Laureen Drab, Matthias Forwick, Akemi Fukumura, Shulan Ge, Shyam Gupta, Arata Kioka, Susumu Konno, Leah J. LeVay, Christian März, Kenji M. Matsuzaki, Erin L. McClymont, Chris Moy, Juliane Müller, Atsunori Nakamura, Takanori Ojima, Fabiana R. Ribeiro, Kenneth D. Ridgway, Oscar E. Romero, Angela L. Slagle, Joseph S. Stoner, Guillaume St-Onge, Itsuki Suto, Maureen D. Walczak, Lindsay L. Worthington, Ian Bailey, Eva Enkelmann, Robert Reece, and John M. Swartz (2015). "Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska," PNAS vol. 112 #49, pp. 15042-15047 [DOI 10.1073/pnas.1512549112] Version of Record Available From (www. pnas.org)
- Language: English
- Date: 2015
- Keywords
- tectonic-climate interactions, orogenesis, Mid-Pleistocene transition, mass flux, ocean drilling