Late Quaternary palaeoenvironmental change in western Staaten Island (54.5° S, 64° W), Fuegian Archipelago
Introduction
Isla de los Estados (54°45′ S, 64°15′ W), is located at the southernmost end of South America, forming part of the province of Tierra del Fuego, Antarctica and South Atlantic Islands. The island, due to its geographical location, conforms a unique and sensitive area for Quaternary palaeoecological and palaeoclimatic studies giving information on the atmospheric and environmental conditions from cold-temperate high latitudes in the Southern Hemisphere.
Pollen records from peat deposits from Isla Grande de Tierra del Fuego (Heusser, 1987, Heusser, 1989a, Heusser, 1989b, Heusser, 1990, Heusser, 1994, Heusser, 1995, Heusser, 1998, Heusser, 2003, Heusser and Rabassa, 1987, Heusser and Rabassa, 1994, Markgraf, 1983, Markgraf, 1991a, Markgraf, 1991b, Markgraf, 1993a, Markgraf, 1993b, Markgraf and Anderson, 1994, Borromei, 1995, Quattrocchio and Borromei, 1998, Borromei and Quattrocchio, 2001, Borromei and Quattrocchio, 2007, Borromei and Quattrocchio, 2008, Borromei et al., 2007, Borromei et al., 2010, Pendall et al., 2001, Grill et al., 2002, Mauquoy et al., 2004), have provided palaeoenvironmental and palaeoclimatic information for the late Pleistocene and Holocene. Only two studies report on the palaeocology and paleoclimate of Isla de los Estados. The first one is a palynological study by Johns (1981) based on three peat cores collected in 1971. No numerical dates are available for these sequences. The second one is based on geochemical analyses from a peat core and a lake sediment core from the northern coastal area covering a record of 16,000–10,000 cal BP (Unkel et al., 2008).
This paper focuses on the pollen analysis of a peat-bog located at Caleta Lacroix (Bahía Franklin, western Isla de los Estados) and the geomorphological analysis of the area to infer the palaeoenvironmental and palaeoclimatic conditions during the last 13,000 years. The comparison with other records from high latitudes of Southern South America will contribute to evaluate the similarities and differences in the patterns of the environmental changes during the late Pleistocene-Holocene and their relation with climatic conditions.
Section snippets
Regional setting
Isla de los Estados, at the southernmost end of South America, is part of the Argentine Province of Isla Grande de Tierra del Fuego. It is located between 54°38′ S and 54°55′ S and 63°48′ W and 64°46′ W (Fig. 1a) ca. 30 km southeast from Península Mitre, Isla Grande de Tierra del Fuego, and separated from it by the Le Maire Strait. Isla de los Estados has a surface area of 496 km2, a maximum E–W length of 62 km, and an average width of 6 km (Niekisch and Schiavini, 1998). It is the southeastern
Pollen analysis
Fossil peat core IDE-1 (Figs. 1b and 3) was taken with a Russian corer. In the laboratory, the core was sub-sampled at 5 cm intervals and the sediments described. A total of 65 fossil pollen samples were obtained. In order to achieve modern pollen data to interpret the palaeovegetation changes from the fossil pollen spectra, 16 surface samples were extracted from the studied area (samples Ms1 to Ms7) and northern coast of the island (samples Ms8 to Ms16) (Fig. 1b). Modern pollen frequencies are
Geomorphology and stratigraphy of the studied area
The area is located at the western sector of the island, in Caleta Lacroix, inside of Bahía Franklin (54°50′ 50.6″ S; 64° 39′ 27.4″ W) (Figs. 2a–d and 3). The site encloses a dune field in an elongated depression limited to the NW and SE by rocky valley sides with steep slopes close to 20°, connecting northeastwards with the widely extended Astelia peatlands. These landforms end abruptly on their southeasterly edge, where they are intercepted by a local, NW-trending stream, which drains into
Modern pollen data
The pollen spectra from surface samples (Fig. 4) represent the principal units of vegetation found in the island: Nothofagus forest, Magellanic Moorland and Andean vegetation. The pollen concentration values of surface samples are not shown in Fig. 4.
- 1
Closed Nothofagus forest: characterized by the highest percentages of Nothofagus dombeyi type (73–98%). The data reveal the relative importance of Drimys winteri (9%) and Misodendrum (27%) and, the lowest values of Empetrum/Ericaceae type. Poaceae
Reconstruction of palaeoenvironmental conditions
During the Last Glacial Maximum (LGM; ca. 24 ka BP; Rabassa, 2008) sea levels were probably stable around 120 and 140 m below present sea level. Under these conditions, Isla de los Estados was connected to the rest of the continent as Isla Grande de Tierra del Fuego was (Unkel et al., 2008, Ponce, 2009, Ponce et al., 2009). The northern coastline of Isla de los Estados, during the LGM, was found at around 100 km on a straight line north of its present position (Ponce et al., 2009). As well, the
Conclusions
The Caleta Lacroix section, located on the westernmost tip of Isla de los Estados provides a unique opportunity to trace the floristic and chronological development of the local and regional vegetation and paleoclimate of the Fuegian realm during late Pleistocene and Holocene. The following conclusions can be drawn from the geomorphological and pollen analyses:
- 1
Modern pollen spectra reflect the principal units of vegetation found in the island: Nothofagus forest, Magellanic Moorland and Andean
Acknowledgements
We acknowledge Brain Menounos (University of Northern British Columbia) for his valuable suggestions and English revision of the manuscript and, two anonymous reviewers for their constructive comments. We thank Adrián Schiavini and colleagues for arranging travel and stay in Isla de los Estados. Argentine Navy and the crew of the “Sobral” ship are acknowledged for their logistical support and travel assistance to get to the island. To INGEOSUR-CONICET, Departamento de Geología, Universidad
References (59)
- et al.
Multiproxy record of Holocene paleoenvironmental change, Tierra del Fuego, Argentina
Palaeogeography, Palaeoclimatology, Palaeoecology
(2010) - et al.
Late Pleistocene - Holocene environments in Valle Carbajal, Fuegian Andes valley, southern south America
Journal of South American Earth Sciences
(2007) - et al.
Holocene Antarctic climate variability from ice and marine sediment cores: insights on ocean–atmosphere interaction
Quaternary Science Reviews
(2010) Late quaternary vegetation and climate of southern Tierra del Fuego
Quaternary Research
(1989)Climate and chronology of Antarctica and adjacent south America over the past 30,000 yr
Palaeogeography, Palaeoclimatology, Palaeoecology
(1989)Late-glacial and Holocene vegetation and climate of subantarctic South America
Review of Palaeobotany and Palynology
(1990)Palaeoecology of a Donatia-Astelia cushion bog, Magellanic Moorland-Subantarctic Evergreen Forest transition, southern Tierra del Fuego, Argentina
Review of Palaeobotany and Palynology
(1995)Deglacial paleoclimate of the American sector of the southern Ocean: late glacial-holocene records from the latitude of Beagle channel (55° S), Argentine Tierra del Fuego
Palaeogeography, Palaeoclimatology, Palaeoecology
(1998)Holocene vegetation and climate changes from a peat pollen record of the forest - steppe ecotone, southwest of Patagonia (Argentina)
Quaternary Science Reviews
(2009)Paleoenvironments and paleoclimates in Tierra del Fuego and southernmost Patagonia, South America
Palaeogeography, Palaeoclimatology, Palaeoecology
(1993)
Younger Dryas in southernmost south America - an update
Quaternary Science Reviews
Late Holocene climatic changes in Tierra del Fuego based on multiproxy analyses of peat deposits
Quaternary Research
Late-glacial and Holocene palaeoenvironmental change in the central Strait of Magellan, southern Patagonia
Palaeogeography, Palaeoclimatology, Palaeoecology
Millennial-scale variability in Southern Hemisphere westerly wind activity over the last 5000 years in SW Patagonia
Quaternary Science Reviews
Multiproxy record of late Pleistocene - Holocene climate and vegetation change in Patagonia
Quaternary Research
Quaternary of Tierra del Fuego, Southernmost South America: an updated review
Quaternary International
Quantitative reconstruction of Holocene precipitation changes in southern Patagonia
Quaternary Research
Deglacial environmental changes on Isla de los Estados (54.4° S), southeastern Tierra del Fuego
Quaternary Science Reviews
Pollen evidence for variations in the southern margin of the westerly winds in SW Patagonia over the last 12,600 years
Quaternary Research
Vegetation and climate dynamics in southern south America: the microfossil record of Laguna Potrok Aike, Santa Cruz, Argentina
Review of Paleobotany and Palynolgy
Mechanisms of Holocene palaeoenvironmental change in the Antarctic Peninsula region
The Holocene
Análisis polínico de una turbera holocénica en el Valle de Andorra, Tierra del Fuego, Argentina
Revista Chilena de Historia Natural
Palynological study of Holocene marine sediments from Bahía Lapataia, Beagle channel, Tierra del Fuego, Argentina
Revista Española de Micropaleontología
Palynology of Holocene marine deposits at Beagle channel, southern Tierra del Fuego, Argentina
Ameghiniana
Late and postglacial paleoenvironments of Tierra del Fuego: terrestrial and marine palynological evidence
Bosques templados de Chile y Argentina.
Evidence of early Holocene glacial advances in southern South America from cosmogenic surface-exposure dating
Geology
A contribution to the Flora and Vegetation of Isla de Los Estados (Staten Island), Tierra del Fuego, Argentina
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