Age of the Fjord Stade moraines in the Disko Bugt region, western Greenland, and the 9.3 and 8.2 ka cooling events Nicolás E. Young a, * , Jason P. Briner a , Dylan H. Rood b, c , Robert C. Finkel d , Lee B. Corbett e, f , Paul R. Bierman e a Department of Geology, University at Buffalo, Buffalo, NY 14260, USA b Scottish Universities Environmental Research Centre (SUREC), East Kilbride G75 0QF, UK c Earth Research Institute, University of California, Santa Barbara, CA 93106, USA d Department of Earth and Planetary Sciences, University of California-Berkeley, Berkeley, CA, USA e Department of Geology, University of Vermont, Burlington, VT 05405, USA f Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA article info Article history: Received 30 June 2012 Received in revised form 12 September 2012 Accepted 17 September 2012 Available online Keywords: Greenland Ice Sheet Moraines 10 Be exposure dating Abrupt climate change abstract Retreat of the western Greenland Ice Sheet during the early Holocene was interrupted by deposition of the Fjord Stade moraine system. The Fjord Stade moraine system spans several hundred kilometers of western Greenland’s ice-free fringe and represents an important period in the western Greenland Ice Sheet’s deglaciation history, but the origin and timing of moraine deposition remain uncertain. Here, we combine new and previously published 10 Be and 14 C ages from Disko Bugt, western Greenland to constrain the timing of Fjord Stade moraine deposition at two locations w60 km apart. At Jakobshavn Isfjord, the northern of two study sites, we show that Jakobshavn Isbræ advanced to deposit moraines ca 9.2 and 8.2e8.0 ka. In southeastern Disko Bugt, the ice sheet deposited moraines ca 9.4e9.0 and 8.5e8.1 ka. Our ice-margin chronology indicates that the Greenland Ice Sheet in two distant regions responded in unison to early Holocene abrupt cooling 9.3 and 8.2 ka, as recorded in central Greenland ice cores. Although the timing of Fjord Stade moraine deposition was synchronous in Jakobshavn Isfjord and southeastern Disko Bugt, within uncertainties, we suggest that Jakobshavn Isbræ advanced while the southeastern Disko Bugt ice margin experienced stillstands during the 9.3 and 8.2 ka events based on regional geomorphology and the distribution of 10 Be ages at each location. The contrasting style of ice-margin response was likely regulated by site-specific ice-flow character- istics. Jakobshavn Isbræ’s high ice flux results in an amplified ice-margin response to a climate perturbation, both warming and cooling, whereas the comparatively low-flux sector of the ice sheet in southeastern Disko Bugt experiences a more subdued response to climate perturbations. Our chro- nology indicates that the western Greenland Ice Sheet advanced and retreated in concert with early Holocene temperature variations, and the 9.3 and 8.2 ka events, although brief, were of sufficient duration to elicit a significant response of the western Greenland Ice Sheet. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Dispersed around the Greenland Ice Sheet (GrIS) periphery, high- velocity marine-terminating outlet glaciers facilitate rapid land-to- ocean transfer of ice and account for up to w50% of the overall mass-balance budget of the ice sheet (Pfeffer et al., 2008; van den Broeke et al., 2009). Consequently, rapid changes in outlet-glacier velocity over the last decade highlight the difficulty in extrapo- lating ice-sheet change into the future, and have also emphasized the dynamic nature in which the GrIS responds to climate change (Joughin et al., 2004; Rignot and Kanagaratnam, 2006; Howat et al., 2007). Reconstructions of outlet-glacier and broader GrIS change extending beyond the modern instrumental record can place important empirical constraints on the sensitivity of ice masses to temperature change and can serve as tests for geophysical ice-sheet models that are used to forecast future ice-sheet dimensions (e.g. Otto-Bliesner et al., 2006; Simpson et al., 2009). Located in Disko Bugt, western Greenland, Jakobshavn Isbræ is the GrIS’ largest outlet glacier, draining w6.5% of the ice-sheet * Corresponding author. Present address: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. E-mail address: nicolasy@ldeo.columbia.edu (N.E. Young). Contents lists available at SciVerse ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev 0277-3791/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.quascirev.2012.09.028 Quaternary Science Reviews 60 (2013) 76e90