Terrestrial cosmogenic 10Be dating of the Última Esperanza ice lobe moraines (52°S, Patagonia) indicates the global Last Glacial Maximum (LGM) extent was half of the local LGM

Attila Çiner*, Mehmet Akif Sarıkaya, Cengiz Yıldırım, Igor Girault, Dominique Todisco, Fabiana Martin, Luis Borrero, Derek Fabel

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Özet

Whether glaciers in the southern hemisphere were asynchronous to those in the north during the global Last Glacial Maximum (gLGM; 26.5–19 ka) is still debated. In Patagonia (South America), numerous ice lobes attained their maximum extents during diverse episodes of the last glacial cycle. To understand the variations in the gLGM vs local LGM record, we studied the Lago Aníbal Pinto area (52°00′ S, 72°40′ E; Chile), where several moraine belts were deposited by one of the eastward-flowing southern Patagonian Ice Sheet (PIS) outlet ice lobes; the Última Esperanza. We report eight 10Be terrestrial cosmogenic nuclides (TCN) surface ages from granitic moraine boulders. Our weighted average age obtained from the southern part of the Río Turbio moraine belt yields 50.7 ± 2.4 ka (oldest boulder age; 53.8 ± 5.3 ka) and confirms the greatest extent of the local Last Glacial Maximum (lLGM) during Marine Isotope Stage 3 (MIS 3) in the previously dated northern moraines from the same belt. Our 10Be TCN age (32.6 ± 2.2 ka) derived from the Dos Lagunas moraine, which makes up the northernmost margin of the Última Esperanza ice lobe's Arauco advance, also validates the MIS 3 timing. Following the formation of Arauco moraines, the Última Esperanza ice lobe was split into three main tributaries in the south, which formed three restricted and previously undated moraine complexes. We dated one of them, the Aníbal Pinto moraine complex. Whereas the highest moraine yielded the oldest age (28.3 ± 2.2 ka), lower moraine's surface that was later truncated as a lacustrine erosional platform, yielded younger boulder ages (weighted average age = 18.9 ± 1.0 ka; oldest boulder age = 19.0 ± 1.5 ka), indicating they were deposited under the Pinto Lake level. Our new age data allow us to propose a new chronology for the Aníbal Pinto moraine complex and consolidate previously published ages from other moraine belts. We attribute the Aníbal Pinto moraine complex to early gLGM (MIS 2), emphasising that the gLGM was half the extent of lLGM in the Última Esperanza ice lobe that underpins its interhemispheric asynchronous character.

Orijinal dilİngilizce
Makale numarası108381
DergiGeomorphology
Hacim414
DOI'lar
Yayın durumuYayınlandı - 1 Eki 2022

Bibliyografik not

Publisher Copyright:
© 2022 Elsevier B.V.

Finansman

This work was funded by the Istanbul Technical University BAP research projects 40610 and 41612 , the Chilean FONDECYT projects 1150845 and 1180272 , the French CNRS PICS project GEOCEBE, and a PhD grant from the “ Institut des Amériques ”. We appreciate the help provided by the National Forest Corporation (CONAF) and the rangers of the Park “Monumento Natural Cueva del Milodón”. We greatly appreciate the very detailed and helpful reviews by Juan-Luis García and Bradley William Goodfellow, who increased the quality of this work. This work was funded by the Istanbul Technical University BAP research projects 40610 and 41612, the Chilean FONDECYT projects 1150845 and 1180272, the French CNRS PICS project GEOCEBE, and a PhD grant from the “Institut des Amériques”. We appreciate the help provided by the National Forest Corporation (CONAF) and the rangers of the Park “Monumento Natural Cueva del Milodón”. We greatly appreciate the very detailed and helpful reviews by Juan-Luis García and Bradley William Goodfellow, who increased the quality of this work. Fabiana Martin reports financial support was provided by FONDECYT (Chile). Dominique Todisco reports financial support was provided by CNRS PICS project GEOCEBE. Attila Ciner reports financial support was provided by Istanbul Technical University TGA-2017-40610. Attila Ciner reports a relationship with Istanbul Technical University that includes: employment.

FinansörlerFinansör numarası
CONAF
Institut des Amériques
National Forest Corporation
Fondo Nacional de Desarrollo Científico y Tecnológico1150845, 1180272
Centre National de la Recherche Scientifique
Istanbul Teknik Üniversitesi41612, TGA-2017-40610, 40610

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