Chronology of Lateglacial ice flow reorganization and deglaciation in the Gotthard Pass area,Central Swiss Alps,based on cosmogenic 10Be and in situ 14C |
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| Institution: | 1. Institute of Geochemistry and Petrology, ETH Zürich, Clausiusstrasse 25, CH-8092 Zürich, Switzerland;2. Laboratory of Ion Beam Physics, ETH Zürich, Schafmattstrasse 20, CH-8093 Zürich, Switzerland;3. Geological Institute, ETH Zürich, Sonneggstrasse 5, CH-8092 Zürich, Switzerland;4. AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Al. Mickiewicza 30, 30-059 Kraków, Poland;5. University of Bern, Institute of Geological Sciences, Baltzerstrasse 1+3, CH-3012 Bern, Switzerland;1. Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada;2. Exxonmobil Upstream Research Company, Houston, TX 77252, United States;1. Department of Geography, Faculty of Arts, University of Ljubljana, Aškerčeva 2, 1000 Ljubljana, Slovenia;2. Department of Earth System Sciences and Environmental Technologies, ISMAR-CNR C/o Area Science Park Basovizza, Q2 Building S.S.14 - Km 163.5, I-34149 Trieste, Italy;3. Department of Mathematics and Geosciences, University of Trieste, Via Weiss 1, 34128 Trieste, Italy;4. Geological Survey of Slovenia, Dimičeva 14, 1000 Ljubljana, Slovenia;1. Department of Geography, University of Tennessee, Knoxville, TN 37996, USA;2. College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;3. Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA;4. Bolin Centre for Climate Research, Department of Physical Geography and Quaternary Geology, Stockholm University, S-106 91 Stockholm, Sweden;5. Department of Physics, Purdue Rare Isotope Measurement Laboratory, Purdue University, West Lafayette, IN 47907, USA;1. School of Earth and Climate Sciences and Climate Change Institute, University of Maine, Orono, ME, 04473, USA;2. Lamont-Doherty Earth Observatory and Department of Earth and Environmental Sciences, Columbia University, Palisades, NY, 10964, USA;3. School of Geography and Archaeology, Palaeoenvironmental Research Unit, National University of Ireland, Galway, Ireland;4. Department of Anthropology, Michigan State University, East Lansing, MI, 48824, USA;1. Earth & Environmental Science Department, New Mexico Tech, Socorro NM 87801, USA;2. Earth & Space Sciences Department, University of Washington, Seattle, WA 98195, USA;3. Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA;4. Department of Physics, Purdue University, West Lafayette, IN 47907-1396, USA;5. Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark 19716, USA;6. Department of Geosciences, University Cologne, 50939 Cologne, Germany;7. Lawrence Livermore National Laboratory, Center for Accelerator Mass Spectrometry, Livermore, CA 94550, USA;8. Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118, USA;9. Department of Earth Sciences, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada;10. Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA;11. NSF Arizona AMS Laboratory, University of Arizona, Tucson, AZ 85721, USA;12. Department of Earth Sciences, Dartmouth College, Hanover NH 03755, USA;13. Woods Hole Oceanographic Institute, Department of Marine Chemistry & Geochemistry, Woods Hole, MA 02543, USA;14. Scripps Institution of Oceanography, Geological Research Division, La Jolla CA 92093, USA;15. Department of Earth, Atmospheric, and Planetary Sciences and Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA;p. School of GeoSciences, University of Edinburgh, Geography Building, Edinburgh EH8 9XP, UK;q. Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA;r. Planetary Science Institute, 1700 E Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA;s. Geochemistry, Lamont-Doherty Earth Observatory (LDEO), Palisades, NY 10964, USA;t. Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA |
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| Abstract: | We reconstruct the timing of ice flow reconfiguration and deglaciation of the Central Alpine Gotthard Pass, Switzerland, using cosmogenic 10Be and in situ 14C surface exposure dating. Combined with mapping of glacial erosional markers, exposure ages of bedrock surfaces reveal progressive glacier downwasting from the maximum LGM ice volume and a gradual reorganization of the paleoflow pattern with a southward migration of the ice divide. Exposure ages of ∼16–14 ka (snow corrected) give evidence for continuous early Lateglacial ice cover and indicate that the first deglaciation was contemporaneous with the decay of the large Gschnitz glacier system. In agreement with published ages from other Alpine passes, these data support the concept of large transection glaciers that persisted in the high Alps after the breakdown of the LGM ice masses in the foreland and possibly decayed as late as the onset of the Bølling warming. A younger group of ages around ∼12–13 ka records the timing of deglaciation following local glacier readvance during the Egesen stadial. Glacial erosional features and the distribution of exposure ages consistently imply that Egesen glaciers were of comparatively small volume and were following a topographically controlled paleoflow pattern. Dating of a boulder close to the pass elevation gives a minimum age of 11.1 ± 0.4 ka for final deglaciation by the end of the Younger Dryas. In situ 14C data are overall in good agreement with the 10Be ages and confirm continuous exposure throughout the Holocene. However, in situ 14C demonstrates that partial surface shielding, e.g. by snow, has to be incorporated in the exposure age calculations and the model of deglaciation. |
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| Keywords: | Lateglacial Deglaciation history Exposure dating |
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