Late Pleistocene and Holocene geomorphologic evolution of Laguna Las Vueltas area, Tierra del Fuego (Argentina)

Alejandro Montes,Ramiro López,Mónica Salemme,Fernando Santiago

doi:10.5027/andgeov47n1-3219

Abstract

Laguna Las Vueltas (LLV) area retains the morphology of a late Pleistocene watershed that was flooded during a mid-Holocene marine transgression. Sediments associated with a paleosol dated at 22,582 cal yr BP reflect subaerial exposure of the area prior to the submergence during the marine transgression. This transgression produced an extensive tidal flat near the mouth of the former LLV watershed by 7,477 cal yr BP. Subsequent decoupling of the Las Vueltas valley from the sea occurred through the growth of a baymouth barrier and a beach-ridge plain to the east. This decoupling turned the lagoon into a pan environment in which subsequent lake-level fluctuations were controlled by climate. A lunette dune developed at the pans in the former lagoon, providing a narrow corridor where humans trapped, killed and processed guanacos as early as 3,402 cal yr BP. Changes in aeolian sedimentation hint at increased aridity during the past 500 years.

Highlights

Shallow and salty lakes, termed “pans” (Shaw and Bryant, 2011; Villarreal and Coronato, 2017) are common coastal features on northeastern Tierra del Fuego
Laguna Las Vueltas (LLV) area retains the morphology of a late Pleistocene watershed that was flooded during a mid-Holocene marine transgression
The coastal area between San Sebastián Bay and Río Grande was not glaciated during most of the Pleistocene (Fig. 1a), but meltwater streams from glaciers to the west reached the coast, and the area was affected by marked sea-level changes accompanying the build-up and decay of the Patagonian ice sheet (Bujalesky et al, 2001; Bujalesky, 2007)

Summary

Introduction

Shallow and salty lakes, termed “pans” (Shaw and Bryant, 2011; Villarreal and Coronato, 2017) are common coastal features on northeastern Tierra del Fuego One of these pans, Laguna Las Vueltas (LLV, Fig. 1) is located within a steppe environment that extends from the Magellan Strait to the cape Viamonte area, south of the Río Grande, Argentina (Collado, 2007). Our specific objectives are to understand the morphology of these watersheds at northeastern Tierra del Fuego, reconstruct the Holocene landscapes in coastal areas and obtain information of climatic changes associated to the sedimentary and geomorphological processes of the area These particular objectives lead to our main objective, which is to increase the understanding of the geomorphologic history of Tierra del Fuego during the period when hunters-gatherers first arrived to southernmost Argentina

Methods

Results

Discussion

Conclusion