Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska Sean P. S. Gulicka,1, John M. Jaegerb, Alan C. Mixc, Hirofumi Asahid, Heinrich Bahlburge, Christina L. Belangerf, Glaucia B. B. Berbelg, Laurel Childressh, Ellen Cowani, Laureen Drabj, Matthias Forwickk, Akemi Fukumural, Shulan Gem, Shyam Guptan, Arata Kiokao, Susumu Konnop, Leah J. LeVayq, Christian Märzr, Kenji M. Matsuzakis,2, Erin L. McClymontt, Chris Moyu, Juliane Müllerv, Atsunori Nakamurao,2, Takanori Ojimao, Fabiana R. Ribeirog, Kenneth D. Ridgwayw, Oscar E. Romerox, Angela L. Slaglej, Joseph S. Stonerc, Guillaume St-Ongey, Itsuki Sutol, Maureen D. Walczakz, Lindsay L. Worthingtonaa, Ian Baileybb, Eva Enkelmanncc, Robert Reecedd, and John M. Swartza aInstitute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78758-4445; bDepartment of Geological Sciences, University of Florida, Gainesville, FL 32611-2120; cCollege of Oceanic & Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503; dKorea Polar Research Institute, Incheon 406-840, Korea; eInstitut für Geologie und Paläontologie, Universität Münster, 48149 Muenster, Germany; fDepartment of Geology and Geological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701; gDepartamento de Oceanografia Física, Química e Geológica, Instituto Oceanográfico, Universidade de São Paulo, São Paulo, SP 05508-120, Brazil; hDepartment of Earth and Planetary Sciences, Northwestern University, Evanston, IL 60208; iDepartment of Geology, Appalachian State University, Boone, NC 28608; jLamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964; kDepartment of Geology, Universitetet i Tromsø, Tromso 9037, Norway; lDepartment of Earth and Planetary Sciences, Nagoya University, Nagoya 464-8601, Japan; mDepartment of Marine Geology, First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, People’s Republic of China; nNational Institute of Oceanography, Dona Paula, Goa 403 004, India; oAtmosphere and Ocean Research Institute, University of Tokyo, Chiba 277-8564, Japan; pDepartment of Earth and Planetary Sciences, Kyushu University, Fukuoka 812-8581, Japan; qInternational Ocean Discovery Program, Texas A&M University, College Station, TX 77845-9547; rSchool of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom; sDepartment of Geology and Paleontology, Tohoku University, Sendai 980-8578, Japan; tDepartment of Geography, University of Durham, Durham DH1 3LE, United Kingdom; uDepartment of Geology, University of Otago, Dunedin 9054, New Zealand; vMarine Geology and Paleontology, Alfred Wegener Institute, 27568 Bremerhaven, Germany; wDepartment of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN 47907-2051; xMARUM - Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany; yInstitut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Rimouski, QC, Canada G5L 3A1; zResearch School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia; aaDepartment of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131; bbCamborne School of Mines, College of Engineering, Mathematics & Physical Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, United Kingdom; ccDepartment of Geology, University of Cincinnati, Cincinnati, OH 45221-0013; and ddDepartment of Geology and Geophysics, Texas A&M University, College Station, TX 77843-3115 EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES Edited by John P. Grotzinger, California Institute of Technology, Pasadena, CA, and approved October 27, 2015 (received for review June 26, 2015) Erosion, sediment production, and routing on a tectonically active within the orogen as it attempts to reestablish equilibrium (3). The continental margin reflect both tectonic and climatic processes; long-term sink for sediment transported out of mountain belts is partitioning the relative importance of these processes remains often in the deep sea, particularly in large submarine fans where controversial. Gulf of Alaska contains a preserved sedimentary sediments accumulate at anomalously high rates (>10 cm/ky) record of the Yakutat Terrane collision with North America. Because compared with deep-sea pelagic sedimentation (6–8). Even higher tectonic convergence in the coastal St. Elias orogen has been roughly > constant for 6 My, variations in its eroded sediments preserved in the sedimentation rates ( 100 cm/ky) proximal to glacially eroded – offshore Surveyor Fan constrain a budget of tectonic material influx, regions (9 14) imply that wet-based glaciers are extremely effi- erosion, and sediment output. Seismically imaged sediment volumes cient agents of erosion. Observations and modeling have argued calibrated with chronologies derived from Integrated Ocean Drilling that erosion rates can influence tectonic processes (15–19), but the Program boreholes show that erosion accelerated in response to timescales of adjustment, and the role of landscape disequilibrium, Northern Hemisphere glacial intensification (∼2.7 Ma) and that the remain unclear. For example, exceptionally high local sedimenta- 900-km-long Surveyor Channel inception appears to correlate with tion rates (100–1000 cm/ky) recorded on the century timescale (13) this event. However, tectonic influx exceeded integrated sediment efflux over the interval 2.8–1.2 Ma. Volumetric erosion accelerated Significance 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 In coastal Alaska and the St. Elias orogen, over the past 1.2 influx by 50–80%. Such a rapid net mass loss explains apparent in- million years, mass flux leaving the mountains due to glacial creases in exhumation rates inferred onshore from exposure dates erosion exceeds the plate tectonic input. This finding under- and mapped out-of-sequence fault patterns. The 1.2-My mass bud- scores the power of climate in driving erosion rates, potential get imbalance must relax back toward equilibrium in balance with feedback mechanisms linking climate, erosion, and tectonics, − tectonic influx over the timescale of orogenic wedge response (mil- and the complex nature of climate tectonic coupling in tran- lions of years). The St. Elias Range provides a key example of how sient responses toward longer-term dynamic equilibration of active orogenic systems respond to transient mass fluxes, and of the landscapes with ever-changing environments. possible influence of climate-driven erosive processes that diverge from equilibrium on the million-year scale. Author contributions: S.P.S.G., J.M.J., A.C.M., and L.J.L. designed research; S.P.S.G., J.M.J., A.C.M., H.A., H.B., C.L.B., G.B.B.B., L.C., E.C., L.D., M.F., A.F., S. Ge, S. Gupta, A.K., S.K., L.J.L., C. März, K.M.M., E.L.M., C. Moy, J.M., A.N., T.O., F.R.R., K.D.R., O.E.R., A.L.S., J.S.S., G.S.-O., tectonic−climate interactions | orogenesis | Mid-Pleistocene transition | I.S., M.D.W., and L.L.W. performed research; S.P.S.G., J.M.J., A.C.M., I.B., E.E., R.R., and J.M.S. mass flux | ocean drilling analyzed data; and S.P.S.G., J.M.J., and A.C.M. wrote the paper. The authors declare no conflict of interest. rogenesis reflects the balance of crustal material entering This article is a PNAS Direct Submission. 1 Oa mountain belt to undergo shortening and uplift versus ma- To whom correspondence should be addressed. Email: [email protected]. 2 terial leaving the orogen through exhumation, erosion, and sedi- Present address: Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8567, Japan. – ment transport (1 5). Perturbations in the influx/efflux from the This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. orogen are expected to result in predictable changes in deformation 1073/pnas.1512549112/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1512549112 PNAS Early Edition | 1of6 Downloaded by guest on September 25, 2021 have been suggested to reflect an unsustainable, short-term the orogen if within the Pamplona Zone fold and thrust belt (16) erosion perturbation due to the Little Ice Age (20). or may reenter the orogen with the subducting Yakutat Terrane Time-varying sediment accumulation rates at individual sites (Fig. 1A). Sediments that bypass the shelf to be deposited on the have been interpreted to reflect an allogenic control on sediment deep-sea Surveyor Fan or within the adjacent Aleutian Trench are production, especially related to a fundamental climate-induced permanently removed from the orogeny, as these sediments will change in terrestrial sediment production in the Pleistocene (21, travel with the Pacific Plate westward to be eventually accreted or 22). An alternate explanation is that autogenic sediment dispersal subducted along the Aleutian system (Fig. 1A) (31). In 2013, In- processes and/or subsequent erosion of accumulated strata can tegrated Ocean Drilling Program (IODP) Expedition 341 drilled a result in an apparent decrease in sediment accumulation rates with transect of sites (U1417-U1421; Figs. 1 and 2) across the Surveyor increasing age [the so-called “Sadler Effect,” first described by Fan in the Gulf of Alaska and Bering–Malaspina slope and shelf Moore and Heath (23)], especially