Late Pleistocene glaciolacustrine MIS 3 record at Fagnano Lake, Central Tierra del Fuego, southern Argentina

Abstract

A late Pleistocene glaciolacustrine record was studied at Fagnano Lake (54°35´S, 67°20´W), central Isla Grande de Tierra del Fuego, southernmost South America. Two profiles from the Río Valdéz outcrop were collected for isotopic, geochemical, sedimentological, and geophysical analyses. The sedimentological characteristics, such as rhythmites, presence of dropstones, absence of fossil record, and scarce presence of organic matter, suggest deposition in an ice-contact lake, possibly dammed by the Fagnano paleoglacier. Organic matter of C3 plant origin suggests certain cold and wet conditions. A chronology of the late Pleistocene outcrop was obtained from five 14C ages resulting in an age-depth model. The time span covered 49.01 cal ka BP to 32.14 cal ka BP. Based on the thickness of the deposit and the calculated average sedimentation rate, the glacial environment could have been present in the study area prior to the last glacial maximum, in agreement with the Inútil-San Sebastián paleoglacier. Both glaciers flowed from the same mountain ice sheet in the Darwin Cordillera, which makes it possible to infer a different behavior of this ice cap from those of the Patagonian Andes, perhaps forced by different atmospheric dynamics and proximity to the wet and cold subantarctic air masses.

Southern Hemisphere Westerly Winds have modulated the formation of laminations in sediments in Lago Fagnano (Tierra del Fuego, Argentina) over the past 6.3 ka

“…2011; Sanci et al . 2021). Lago Fagnano’s location and orientation make this site an excellent place to examine the Holocene variations of the Southern Hemisphere Westerly Winds (SHWW), because of the weaker rainshadow effect owing to the lower elevation of the Andes running parallel to the westerlies (Fig.…”

Introduction to the SHeMax thematic set and prospects for LGM research in the Southern Hemisphere

“…Glaciers were of greater extent during MIS 3 (e.g. Sanci et al, 2021; Shulmeister et al, 2019) when compared to the traditionally defined “global” LGM, which had a more subdued signature in many Southern Hemisphere records, perhaps due to to relatively increased aridity in the Southern Hemisphere at the global LGM (Berman et al, 2016). Further, the evidence across the Southern Hemisphere for multiple glacial advances spanning the broad period 32–18 kyr (e.g.…”

“…Romina Sanci and co-authors (Sanci et al, 2021) describe the Late Pleistocene glaciolacustrine MIS 3 record at Fagnano Lake, Central Tierra del Fuego, southern Argentina . Like the glacial records from New Zealand this site indicates a relatively early onset of full glacial conditions (cf.…”