New insights into paleoenvironmental changes in Laguna Potrok Aike, southern Patagonia, since the Late Pleistocene: The PASADO multiproxy record

Abstract

A series of long sediment cores was retrieved from Laguna Potrok Aike, Southern Patagonia, within the framework of PASADO (Potrok Aike Maar Lake Sediment Archive Drilling Project), an ICDP (International Continental Scientific Drilling Program) lake drilling project. This maar lake, located at 52°S, 70°W in the Province of Santa Cruz (Argentina), in the southernmost continental area of the world, is one of the few permanent lakes in the region, providing a unique continuous paleoclimatic and paleoecological lacustrine record for the last glacial cycle. Previous multiproxy studies of this site have characterized the environmental history of these dry lands in the Patagonian Steppe for the last 16 cal. ka BP. This new series of sediment cores provides a much longer record of climate variability in Southern Patagonia since 51.3 cal. ka BP. Using a multiproxy strategy, a set of samples (mostly from core catcher material) was analyzed for physical properties, rock magnetism, geochemistry, CNS elemental analysis, stable isotopes, pollen and diatoms. This preliminary multiproxy limnogeological interpretation sheds new light on the regional Pleistocene and Holocene environmental history, revealing lake-level variations through time and identifying time windows of interest where higher resolution analyses will be carried out.

Paleoenvironmental conditions define current sustainability of microbial populations in Laguna Potrok Aike sediments, Argentina

“…All analyses were performed using STATISTICA ® (data analysis software system) version 7.0 (StatSoft, Inc.). Correlation between cores 5022-1A and 5022-1D was achieved by using magnetic susceptibility profiles and supported by visual characteristics on the split cores (Recasens et al 2012). The present age model ( Fig.…”

“…This endorheic basin represents a crucial site to reconstruct the position of the Westerlies, which are the major climatic driving force within the area ). The basin geometry, OM and microfossil records of Laguna Potrok Aike have been addressed extensively in previous publications (Mayr et al 2009;Gebhardt et al 2012;Recasens et al 2012). Although its water column has a maximum depth of 100 m, the lake is polymictic due to the persistent overturn caused by the Westerlies (average wind speed: 7.4 m/s).…”

“…38 to 33 and 7 to 1 ka ago; Zolitschka et al 2013) correspond to high microbial colonization of the sediment associated with a return to pelagic conditions and important nutrient fluxes into the Laguna Potrok Aike closed-basin. The recovery of primary productivity (Recasens et al 2012) also led to OM sources favorable to microbial development.…”

Climate history of the Southern Hemisphere Westerlies belt during the last glacial–interglacial transition revealed from lake water oxygen isotope reconstruction of Laguna Potrok Aike (52° S, Argentina)

“…It might have been strengthened by the thick Patagonian Ice Sheet covering the southern Andes, which might have increased adiabatic warming and drying of subsiding air masses coming from westerly directions. This föhn-wind effect could be very pronounced in a cold and dry environment during the glacial, which is corroborated by palynological studies of Laguna Potrok Aike sediments (Recasens et al, 2012). At Lake Hoare in the modern McMurdo Dry Valley of Antarctica, strong and dry regional föhn winds heat adiabatically by about 20 • C (from −30 to −10 • C) upon their descent from the surrounding ice plateau, even in sunless austral winters (Clow et al, 1988).…”

“…Palynological and geochemical studies based on the Laguna Potrok Aike sediments have shown the long-term environmental and climatic changes in southern Patagonia throughout the last glacialinterglacial cycle and shed light on the behaviour of the SHW during this transition (e.g. Recasens et al, 2012;Hahn et al, 2013;Mayr et al, 2013;Zhu et al, 2013).…”