Ángel Rodés

Small, isolated glacial catchments as priority targets for cosmogenic surface exposure dating of Pleistocene climate fluctuations, southeastern Pyrenees

A new 10 Be data set from a small glacial catchment in the Pyrenees confirms almost full glacier extent during Marine Isotope Stage (MIS) 2, extends the oldest cosmogenic exposure ages of moraines in this mountain range to MIS 5, and constrains paleoclimate reconstructions in the Mediterranean region. It also illustrates the advantageous conditions for the long-term preservation of terminal moraines provided by small, low-gradient glacier catchments that did not merge with compound ice masses even during glacial maxima. These small, gently sloping, and isolated glacier catchments are proposed as priority targets for terrestrial cosmogenic nuclide dating of peak Pleistocene glacier advances, providing scope for greater accuracy in interregional paleoclimatic correlations.

The deglaciation of coastal areas of southeast Greenland.

Large marine-terminating glaciers around the margins of the Greenland Ice Sheet have retreated, accelerated and thinned over the last two decades. Relatively little is known about the longer term behaviour of the Greenland Ice Sheet, yet this information is valuable for assessing the significance of modern changes. We address this by reporting 11 new beryllium-10 (10Be) exposure ages from previously uninvestigated coastal areas across southeast Greenland. The new ages are combined with existing data from the region to assess the timing of glacier retreat after the Last Glacial Maximum. The results show that deglaciation occurred first in the north of the region (~68°N) and progressed southwards. This north–south progression is attributed to the influence of the warm Irminger Current on the ice margin. Areas in the south of the region were isolated from the warm waters by the shallow bathymetry of the continental shelf. This demonstrates that oceanographic forcing paced the deglaciation of southeast Greenland through the Younger Dryas and early Holocene. In most areas of southeast Greenland bedrock ages are systematically older than their counterpart boulder samples; this offset is likely the result of inherited 10Be content in bedrock surfaces. This suggests that subglacial erosion during the last glacial cycle was insufficient to completely remove pre-existing 10Be content. Alternatively, this pattern may be the signature of a substantial retreat and advance cycle prior to final Holocene deglaciation.

Corrigendum to “The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica” [Earth and Planetary Science Letters 469 (2017) 42–52]

This corrigendum fixes an error in the reporting of 21Ne concentrations, which affected one batch of samples that included the bedrock depth profile from which cosmogenic 10Be, 26Al and 21Ne were modelled to constrain the age and exposure history of the Patriot Hills (Fig. 8 in the manuscript). Re-modelling the cosmogenic nuclide data using the corrected 21Ne data yields an apparent exposure age of 3.5–5.1 Ma. This corrects an age published as 2.1–2.6 Ma in Sugden et al. (2017), and reinforces the conclusion of the original paper that the glacial trimline is pre-Quaternary and that the climatic conditions necessary for its erosion last occurred in the Mid-Miocene. The revised Supplementary Table 1 has been updated with corrected 21Ne concentrations and consistent reporting of 10Be concentrations. The revised Supplementary Table 2 has been updated with 21Ne exposure ages for the affected batch of samples. Below, we describe the revised model results and present a revised Fig. 8. Tables 1 and 2, Fig. 8 and its caption replace those in the original paper. The corrections reinforce the conclusions of the original paper.

Be-10 dating of erratics at Hell Creek (Coast Mountains, BC, Canada)

Be dating of erratics at Hell Creek (Coast Mountains, BC, Canada) M. ORTUÑO*, S. EVANS, J.J. CLAGUE, R., PALLÀS, A. RODÉS, A. CUMAN, R. BRAUCHER AND D. BOURLÈS RISKNAT group, Fac. Dept. Geodinàmica i Geofísica, Univ. de Barcelona, Spain (*correspondence: maria.ortuno@ub.edu) Dept. of Earth Sciencies, Univ. of Waterloo, ON, Canada Dept. of Earth Sciencies, Simon Fraser Univ., BC, Canada Dipt.Geoscienze, Univ.degli Studi di Padova, Italy CEREGE UMR 6635, Plateau de l’Arbois 13545, Aix en Provence, France