Cross‐cutting moraines reveal evidence for North Atlantic influence on glaciers in the tropical Andes

• Published in: Journal of Quaternary Science
• Main Authors: Smith, Jacqueline A., Rodbell, Donald T.
• Other Authors: National Geographic Society Committee for Research and Exploration, College of Saint Rose, Union College
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2010
• Subjects: North Atlantic
• Online Access: http://dx.doi.org/10.1002/jqs.1393; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.1393; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.1393

Abstract Surface exposure dating of boulders on an exceptionally well‐preserved sequence of moraines in the Peruvian Andes reveals the most detailed record of glaciation heretofore recognised in the region. The high degree of moraine preservation resulted from dramatic changes in the flow path of piedmont palaeoglaciers at the southern end of the Cordillera Blanca (10° 00′ S, 77° 16′ W), which, in turn, generated a series of cross‐cutting moraines. Sixty 10 Be surface exposure ages indicate at least four episodes of palaeoglacier stabilisation (>65, ca. 65, ca. 32 and ca. 18–15 ka) and several minor advances or stillstands on the western side of the Nevado Jeulla Rajo massif. The absence of ages close to the global Last Glacial Maximum (ca. 21 ka) suggests that if an advance culminated at that time any resulting moraines were subsequently overridden. The timing of expanded ice cover in the central Peruvian Andes correlates broadly with the timing of massive iceberg discharge (Heinrich) events in the North Atlantic Ocean, suggesting a possible causal connection between southward migration of the Intertropical Convergence Zone during Heinrich events and a resultant increase in precipitation in the tropical Andes. Copyright © 2010 John Wiley & Sons, Ltd.