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Proc Natl Acad Sci U S A. 2015 Dec 8;112(49):15042-7. doi: 10.1073/pnas.1512549112. Epub 2015 Nov 23.

Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska.

Author information

1
Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78758-4445; sean@ig.utexas.edu.
2
Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120;
3
College of Oceanic & Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503;
4
Korea Polar Research Institute, Incheon 406-840, Korea;
5
Institut für Geologie und Paläontologie, Universität Münster, 48149 Muenster, Germany;
6
Department of Geology and Geological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701;
7
Departamento de Oceanografia Física, Química e Geológica, Instituto Oceanográfico, Universidade de São Paulo, São Paulo, SP 05508-120, Brazil;
8
Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL 60208;
9
Department of Geology, Appalachian State University, Boone, NC 28608;
10
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964;
11
Department of Geology, Universitetet i Tromsø, Tromso 9037, Norway;
12
Department of Earth and Planetary Sciences, Nagoya University, Nagoya 464-8601, Japan;
13
Department of Marine Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, People's Republic of China;
14
National Institute of Oceanography, Dona Paula, Goa 403 004, India;
15
Atmosphere and Ocean Research Institute, University of Tokyo, Chiba 277-8564, Japan;
16
Department of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581, Japan;
17
International Ocean Discovery Program, Texas A&M University, College Station, TX 77845-9547;
18
School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom;
19
Department of Geology and Paleontology, Tohoku University, Sendai 980-8578, Japan;
20
Department of Geography, University of Durham, Durham DH1 3LE, United Kingdom;
21
Department of Geology, University of Otago, Dunedin 9054, New Zealand;
22
Marine Geology and Paleontology, Alfred Wegener Institute, 27568 Bremerhaven, Germany;
23
Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN 47907-2051;
24
MARUM - Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany;
25
Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Rimouski, QC, Canada G5L 3A1;
26
Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia;
27
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131;
28
Camborne School of Mines, College of Engineering, Mathematics & Physical Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, United Kingdom;
29
Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013;
30
Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843-3115.
31
Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78758-4445;

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 6 My, 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 increases 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.

KEYWORDS:

Mid-Pleistocene transition; mass flux; ocean drilling; orogenesis; tectonic−climate interactions

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