Geomorphology and soils distribution under paraglacial conditions in an ice-free area of Admiralty Bay, King George Island, Antarctica

doi:10.1016/j.catena.2010.12.007

CATENA

Volume 85, Issue 3, June 2011, Pages 194-204

https://doi.org/10.1016/j.catena.2010.12.007 Get rights and content

Abstract

The main pedological, geomorphological and cryogenic features of Keller Peninsula, part of Admiralty Bay, King George Island, Maritime Antarctica, were mapped and quantified with emphasis on the relationship between the ice retreat process, melt-out, landform development and soil distribution. Moraines, protalus, scree slopes, inactive glacial cirques, uplift marine terraces, biogenic landforms, arêtes and Felsenmeer were mapped. Scree slope is the main landform, covering approximately 25% of the peninsula, indicating prominent paraglacial features. Inherited, glacial landforms, such as lateral moraines, highland plateau and exhumed U shaped-valleys, are now being exposed in north Keller by ice shrinkage of former ice protecting cover. Landforms influenced soil formation and stability. Cryosols and Leptosols (WRB) roughly corresponding to Gelisols and Entisols (SSS), respectively, are the most common soil classes, with an overall tendency of absent permafrost in the coastal areas, changing to sporadic permafrost at mid-slope, and discontinuous permafrost with greater altitude and substrate stability.

Research Highlights

► Periglacial and paraglacial geomorphology of Antarctica. ► Weathering and soil formation of polar regions. ► Cryosols and active layer in Antarctica; sulfate-affected soils of Antarctica. ► Landscape evolution and climate change in Antarctica. ► Soils and landform relationships in polar regions.

Introduction

The landscape of ice-free areas of Maritime Antarctica results from a recent ice retreat phase in a cold and relatively wet environment, in which freezing and thawing processes are the primary mechanisms, although some features can be inherited from previous cycles (André, 2003). Hence, frost shattering and the myriad of related processes (for example cryoplanation, nivation, and ablation) are locally enhanced, due to a very rapid increase in average temperatures in this part of Antarctica during the last decade.

Previous studies in the South Shetland Islands conclude that these were affected by two Pleistocene glaciations (John and Sudgen, 1971). During the climax of the Quaternary glaciations, there was a single, continuous ice-sheet linking all South Shetlands. During the last glaciation, each Island developed its own ice-sheet which covered most present-day ice-free areas (Pallàs et al., 1995).

Frequent freeze-and-thaw is the main factor in rock disintegration in cold regions (Boelhouwers et al., 2003). The manifestation of physical weathering in Maritime Antarctica is extreme due mainly to relatively high moisture availability (Simas et al., 2008).

Detailed data on pedo-geomorphology of Antarctica is largely restricted to frigid areas, especially from south Victoria Land. There is some detailed information on sub-Antarctic soils and landforms referring to Marion Island and South Georgia (Boelhouwers et al., 2000). According to Walton (1984) there is a need for integrated biological, pedological and geomorphological studies in the Antarctic Peninsula, not yet fulfilled to this day. This requires the interpretation of biological data combined with edaphic and geomorphological studies to fill the gap in integrated knowledge of Maritime Antarctica landscapes.

The objective of the present work is to describe and map the main landforms and cryogenic features of Keller Peninsula, King George Island in 1:5000 scale and study the relationship between landscape and soil formation in this part of Maritime Antarctica.

Section snippets

Study area

Keller Peninsula is located in Admiralty Bay, King George Island (Fig. 1), between the Martel and MacKellar Inlets. It covers approximately 500 ha, with a north–south length of 4 km and less than 2 km in width. Mean annual air temperature is − 1.8 °C and precipitation averages 360 mm/year (Table 1). Climate is typical of Maritime Antarctica, but somewhat warmer due to the Peninsula's inner position in Admiralty Bay (Rakusa-Suszczewski et al., 1993, Tricart, 1973).

The relief ranges from 0 to 340 meters

Landforms and processes: general features

Eighteen geomorphological units were identified and mapped in Keller Peninsula (Fig. 2, Table 2). The snow banks were classified as a separate unit, as it was virtually impossible to infer the underlying features. Scree slopes are the predominant landform occupying approximately 25% of the ice-free area, followed by talus slopes (10.7%), indicating the active periglacial erosion in this mountainous area.

Overall, the landforms of Keller can be described as paraglacial, due to the recent exposure

Conclusions

The main geomorphological and cryogenic features of Keller Peninsula are typical of mixed paraglacial and periglacial conditions, encompassing ice retreat process, snow melting and recent subaerial, ice-free landform development. Moraines, protalus, inactive rock glaciers, uplift marine terraces, and Felsenmeer were identified and quantified, where depositional features are dominant.

Pre-glacial, relict landforms such as lateral moraines, highland plateaux and exhumed unglaciated valleys are now

Acknowledgments

We thank the Brazilian Antarctic Program (PROANTAR) and the Ministry of Science and Technology (CNPq) for financing the IPY Project (CNPq, Cryosols of Maritime Antarctica). Logistical support from the Brazilian Navy to undertake the field work, flights and photograph cover of Admiralty Bay, was greatly appreciated. This is a contribution of INCT-Criosfera, TERRANTAR group.

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Geomorphology and soils distribution under paraglacial conditions in an ice-free area of Admiralty Bay, King George Island, Antarctica

Abstract

Research Highlights

Introduction

Section snippets

Study area

Landforms and processes: general features

Conclusions

Acknowledgments

Do periglacial landscape evolve under periglacial condition?

Geomorphology

Periglacial phenomena in the South Shetland Islands

Attempt at reconstructing the ancient coastal geomorphology and littoral environment in the South Shetland Islands

Patterned gravel beaches in the South Shetland Islands

Mesozoic and Cenozoic Stratigraphic units in parts of the South Shetlands and northern Antarctica peninsula

Studia Geol. Pol.

Geomorphology of debris flows at Junior's Kop, Marion Island

Earth Surf. Process. Landf.

The Maritime Subantarctic: a distinct periglacial environment

Geomorphology

Holocene glacier fluctuations in the South America and Antarctica

Quatern. Sci. Rev.

Centro Nacional de Pesquisa de solos

The role of biological weathering in periglacial areas: a study of weathering rinds in south Iceland

Geomorphology

The Periglacial Environment

Particle-size analysis

Rock and Landforms

Observations of some periglacial features and their palaeonvironmental implications on sub-Antarctic islands Marion and Kerguelen S

Afr. J. Antarct. Res.

Mechanical weathering in the Antarctic: a maritime perspective

Observations on “cryoplanation” benches in Antarctica

Antarctic Sci.

Modern research perspectives relating to permafrost creep and rock glaciers: a discussion

Permafrost Periglac. Process.