Late-glacial fluctuations of two southern Patagonia outlet glaciers revealed by high-resolution seismic surveys

LODOLO, EMANUELE; LOZANO, JORGE; DONDA, FEDERICA; BRAN, DONALD; BARADELLO, LUCA; TASSONE, ALEJANDRO; ROMEO, ROBERTO; PATERLINI, MARCELO; GROSSI, MAURIZIO; CAFFAU, MAURO; VILAS, JUAN FRANCISCO

QUATERNARY RESEARCH

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2020 p. 1 - 14

0033-5894

Lago Argentino hosts various calving glaciers, among them the famousPerito Moreno. Whereasthe onland late Pleistocene? Holoceneglacialhistoryisratherwellconstrained,thesubmergedglacier-relatedfeatureswereuntilnowundisclosed.Herewe present a series of high-resolution seismic profiles revealing moraine bodies associated with the late-glacial glacier dynamics and the first bathymetric map of the Brazo Rico and Brazo Sur, the two southern arms of Lago Argentino. At the eastern termination of Brazo Rico, we identified at the lake floor the submerged expression of the Puerto Bandera 3 moraine mapped onshore,whichrepresentstheoldestevent (12,660±70calyrBPoldestminimumage)recognizedinthislakearm,andseven other younger events expressed by a series of terminal and recessional moraines. Along the Brazo Sur, few moraine bodies have been imaged by seismic data. Here, the youngest temporal constraint comes from the Frías moraine (ca. 6000 cal yr BP),whichclosesoffthesouthernendoftheBrazoSur.Attheconfluenceofthe twoarms,the PeritoMorenoandthe former Fríasglaciermergedand flowedtowardeastduringtheirlate-glacialmaximumadvance (i.e.,PuertoBandera 1moraine).The subaqueous evidence of moraine bodies testifies to the occurrence of previously undocumented pulses of the Perito Moreno and former Frías glaciers within the general phase of late Pleistocene?Holocene regression.