Submarine landforms related to glacier retreat in a shallow Antarctic fjord

2016 ◽  
Vol 28 (6) ◽  
pp. 475-486 ◽  
Author(s):  
Anne-Cathrin Wölfl ◽  
Nina Wittenberg ◽  
Peter Feldens ◽  
H. Christian Hass ◽  
Christian Betzler ◽  
...  
Keyword(s):  
Late Holocene ◽  
Outer Part ◽  
Ice Age ◽  
South Shetland Islands ◽  
Potter Cove ◽  
Swath Bathymetry ◽  
Depositional Settings ◽  
Submarine Landforms ◽  
Acoustic Facies ◽  
Facies Types

AbstractSince the Last Glacial Maximum, ice has retreated through the fjords of the South Shetland Islands leaving a valuable record of submarine landforms behind. In this study, glacial landforms and sub-bottom characteristics have been mapped to investigate the late Holocene retreat behaviour of the Fourcade Glacier and to delineate past environmental processes in Potter Cove, King George Island. The comprehensive datasets include high-resolution swath bathymetry, shallow seismic profiling and one sediment core. Moraines, moraine incisions and glacial lineations were mapped on the sea floor in the inner part of the cove, whereas pockmarks, ice scour marks and channel structures were identified in the outer part. Sub-bottom characteristics have been assigned to different acoustic facies types indicating different depositional settings. The results reveal glacial recessions as well as stillstands and potential readvances during the late Holocene. Furthermore, the sediment record indicates that the Fourcade Glacier was situated inside the inner cove during the Little Ice Age (500–100 cal yr bp).

scholarly journals Seafloor geomorphology of western Antarctic Peninsula bays: a signature of ice flow behaviour

2018 ◽  
Vol 12 (1) ◽  
pp. 205-225 ◽  
Author(s):  
Yuribia P. Munoz ◽  
Julia S. Wellner
Keyword(s):  
Antarctic Peninsula ◽  
Numerical Models ◽  
Ice Age ◽  
South Shetland Islands ◽  
Schematic Model ◽  
Western Antarctic Peninsula ◽  
Ice Flow ◽  
Swath Bathymetry ◽  
Glacial Dynamics ◽  
Submarine Landforms

Abstract. Glacial geomorphology is used in Antarctica to reconstruct ice advance during the Last Glacial Maximum and subsequent retreat across the continental shelf. Analogous geomorphic assemblages are found in glaciated fjords and are used to interpret the glacial history and glacial dynamics in those areas. In addition, understanding the distribution of submarine landforms in bays and the local controls exerted on ice flow can help improve numerical models by providing constraints through these drainage areas. We present multibeam swath bathymetry from several bays in the South Shetland Islands and the western Antarctic Peninsula. The submarine landforms are described and interpreted in detail. A schematic model was developed showing the features found in the bays: from glacial lineations and moraines in the inner bay to grounding zone wedges and drumlinoid features in the middle bay and streamlined features and meltwater channels in the outer bay areas. In addition, we analysed local variables in the bays and observed the following: (1) the number of landforms found in the bays scales to the size of the bay, but the geometry of the bays dictates the types of features that form; specifically, we observe a correlation between the bay width and the number of transverse features present in the bays. (2) The smaller seafloor features are present only in the smaller glacial systems, indicating that short-lived atmospheric and oceanographic fluctuations, responsible for the formation of these landforms, are only recorded in these smaller systems. (3) Meltwater channels are abundant on the seafloor, but some are subglacial, carved in bedrock, and some are modern erosional features, carved on soft sediment. Lastly, based on geomorphological evidence, we propose the features found in some of the proximal bay areas were formed during a recent glacial advance, likely the Little Ice Age.

scholarly journals Seafloor geomorphology of western Antarctic Peninsula bays: a signature of ice flow behaviour

2017 ◽  
Author(s):  
Yuribia P. Munoz ◽  
Julia S. Wellner
Keyword(s):  
Antarctic Peninsula ◽  
Ice Age ◽  
South Shetland Islands ◽  
Schematic Model ◽  
Western Antarctic Peninsula ◽  
Ice Flow ◽  
Swath Bathymetry ◽  
Geomorphic Features ◽  
Submarine Landforms ◽  
Glacial Advance

Abstract. Glacial geomorphology has been used in Antarctica to reconstruct ice advance and retreat across the continental shelf during the Last Glacial Maximum. Analogous geomorphic assemblages are found in glaciated fjords and can be used in a similar manner to interpret the glacial history in those areas. In addition, understanding the distribution of submarine landforms in bays and the local controls exerted on ice flow can help improve ice-sheet models through these complicated drainage areas. We present multibeam swath bathymetry from several bays in the South Shetland Islands and the western Antarctic Peninsula. The submarine landforms are described and interpreted in detail. A schematic model was developed showing the features found in the bays; from flutings and moraines in the inner bay, to grounding zone wedges and drumlins in the middle bay, and streamlined features and meltwater channels in the outer bay areas. In addition, we analysed local variables in the bays and observe that: 1) bay length and width exert a control on the number of landforms found in the bays, the geometry of the bays dictates the types of features that form; 2) bays with shallower water depths tend to form geomorphic features that suggest rapid decoupling of grounded ice from the seafloor; 3) the smaller seafloor features are present only in the smaller glacial systems indicating that short-lived atmospheric and oceanographic fluctuations, responsible for the formation of these landforms, are only recorded in these smaller systems; and 4) meltwater channels are abundant on the seafloor, however some are subglacial, carved in bedrock, and some are modern erosional features, carved on soft sediment. Lastly, based on geomorphological evidence, we propose the features found in some of the inner bay areas were formed during a recent glacial advance, likely the Little Ice Age.

scholarly journals Photosynthetic light requirements and vertical distribution of macroalgae in newly ice-free areas in Potter Cove, South Shetland Islands, Antarctica

Polar Biology ◽  
2015 ◽  
Vol 39 (1) ◽  
pp. 153-166 ◽  
Author(s):  
D. Deregibus ◽  
M. L. Quartino ◽  
G. L. Campana ◽  
F. R. Momo ◽  
C. Wiencke ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
South Shetland Islands ◽  
Potter Cove ◽  
Shetland Islands ◽  
Light Requirements

Succession of Antarctic benthic algae (Potter Cove, South Shetland Islands): structural patterns and glacial impact over a four-year period

Polar Biology ◽  
2017 ◽  
Vol 41 (2) ◽  
pp. 377-396 ◽  
Author(s):  
Gabriela L. Campana ◽  
Katharina Zacher ◽  
Dolores Deregibus ◽  
Fernando Roberto Momo ◽  
Christian Wiencke ◽  
...  
Keyword(s):  
Benthic Algae ◽  
South Shetland Islands ◽  
Potter Cove ◽  
Structural Patterns ◽  
Shetland Islands

scholarly journals Late Holocene intensification of the westerly winds at the subantarctic Auckland Islands (51° S), New Zealand

2017 ◽  
Author(s):  
Imogen M. Browne ◽  
Christopher M. Moy ◽  
Christina R. Riesselman ◽  
Helen L. Neil ◽  
Lorelei G. Curtin ◽  
...  
Keyword(s):  
New Zealand ◽  
Late Holocene ◽  
Drainage Basin ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Ice Age ◽  
The Pacific ◽  
Westerly Winds ◽  
Latitudinal Position ◽  
Paleoclimate Records

Abstract. The Southern Hemisphere westerly winds (SHWW) play a major role in controlling wind-driven upwelling of Circumpolar Deep Water (CDW) and outgassing of CO2 in the Southern Ocean on interannual to glacial-interglacial timescales. Despite their significance in the global carbon cycle, our understanding of millennial-scale changes in the strength and latitudinal position of the westerlies during the Holocene (especially since 5000 yr BP) is limited by a scarcity of paleoclimate records from comparable latitudes. Here, we reconstruct middle to late Holocene variability in the SHWW using a fjord sediment core collected from the subantarctic Auckland Islands (51° S, 166° E), located in the modern centre of the westerly wind belt. Drainage basin response to variability in the strength of the SHWW at this latitude is reconstructed from downcore variations in magnetic susceptibility (MS) and bulk organic δ13C and atomic C/N, which monitor influxes of lithogenous and terrestrial vs marine organic matter, respectively. The hydrographic response to SHWW variability is reconstructed using benthic foraminifer δ18O and δ13C, both of which are influenced by the isotopic composition of shelf water masses entering the fjord. Using these data, we provide marine and terrestrial-based evidence for increased wind strength from ~ 1600–900 yr BP at subantarctic latitudes that is broadly consistent with previous studies of vegetation response to climate at the Auckland Islands. Comparison with a SHWW reconstruction using similar proxies from Fiordland suggests a northward migration of the SHWW over New Zealand at the beginning of the Little Ice Age (LIA). Comparison with paleoclimate and paleoceanographic records from southern South America and the western Antarctic Peninsula indicates a late Holocene strengthening of the SHWW after ~ 1600 yr BP that appears to be broadly symmetrical across the Pacific basin, although our reconstruction suggests that this symmetry breaks down during the LIA. Contemporaneous increases in SHWW at localities either side of the Pacific in the late Holocene are likely controlled atmospheric teleconnections between the low and high latitudes and by variability in the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO).

scholarly journals Mapping Glacier Forelands Based on UAV BVLOS Operation in Antarctica

2020 ◽  
Vol 12 (4) ◽  
pp. 630
Author(s):  
Maciej Dąbski ◽  
Anna Zmarz ◽  
Mirosław Rodzewicz ◽  
Małgorzata Korczak-Abshire ◽  
Izabela Karsznia ◽  
...  
Keyword(s):  
Ice Age ◽  
South Shetland Islands ◽  
Ground Moraine ◽  
King George Island ◽  
Ice Flow ◽  
Tidewater Glaciers ◽  
Geomorphological Mapping ◽  
Digital Elevation ◽  
Glacial Dynamics ◽  
Elevation Model

The aim of this article is to show geomorphological mapping of remote Antarctic locations using images taken by a fixed-wing unmanned aerial vehicle (UAV) during the Beyond Visual Line of Sight (BVLOS) operations. We mapped landform assemblages developed in forelands of Ecology Glacier (EGF), Sphinx Glacier (SGF) and Baranowski Glacier (BGF) in Antarctic Specially Protected Area No. 128 (ASPA 128) on King George Island (South Shetland Islands) and inferred about glacial dynamics. The orthophoto and digital elevation model allowed for geomorphological mapping of glacial forelands, including (i) glacial depositional landforms, (ii) fluvial and fluvioglacial landforms, (iii) littoral and lacustrine landforms, (iv) bodies of water, and (v) other. The largest area is occupied by ground moraine and glacial lagoons on EGF and BGF. The most profound features of EGF are the large latero-frontal moraine ridges from Little Ice Age and the first half of the 20th century. Large areas of ground moraine, frequently fluted and marked with large recessional moraine ridges, dominate on SGF. A significant percentage of bedrock outcrops and end moraine complexes characterize BGF. The landform assemblages are typical for discontinuous fast ice flow of tidewater glaciers over a deformable bed. It is inferred that ice flow velocity decreased as a result of recession from the sea coast, resulting in a significant decrease in the length of ice cliffs and decrease in calving rate. Image acquisition during the fixed-wing UAV BVLOS operation proved to be a very robust technique in harsh polar conditions of King George Island.

Mid to late Holocene climate evolution of the Lake Telmen Basin, North Central Mongolia, based on palynological data

2003 ◽  
Vol 59 (3) ◽  
pp. 353-363 ◽  
Author(s):  
Sarah J. Fowell ◽  
Barbara C.S. Hansen ◽  
John A. Peck ◽  
P. Khosbayar ◽  
Enebish Ganbold
Keyword(s):  
Late Holocene ◽  
Ice Age ◽  
Cold Temperatures ◽  
North Central ◽  
Central Mongolia ◽  
Decadal Scale ◽  
Moisture Balance ◽  
Climate Evolution ◽  
Maximum Humidity

AbstractPalynological and sedimentological data from Lake Telmen, in north-central Mongolia, permit qualitative reconstruction of relative changes in moisture balance throughout the mid to late Holocene. The climate of the Atlantic period (7500–4500 yr ago) was relatively arid, indicating that Lake Telmen lay beyond the region of enhanced precipitation delivered by the expanded Asian monsoon. Maximum humidity is recorded between ∼4500 and 1600 cal yr B.P., during the Subboreal (4500–2500 yr ago) and early Subatlantic (2500 yr–present) periods. Additional humid intervals during the Medieval Warm Epoch (∼1000–1300 A.D. or 950–650 ago) and the Little Ice Age (1500– 1900 A.D. or 450–50 yr B.P.) demonstrate the lack of long-term correlation between temperature and moisture availability in this region. A brief aridification centered around 1410 cal yr B.P. encompasses a decade of cold temperatures and summer frost between A.D. 536 and 545 (1414–1405 yr B.P.) inferred from records of Mongolian tree-ring widths. These data suggest that steppe vegetation of the Lake Telmen region is sensitive to centennial- and decadal-scale climatic perturbations.

Ascidians (Tunicata, Ascidiacea) of Potter Cove, South Shetland Islands, Antarctica

1998 ◽  
Vol 10 (2) ◽  
pp. 147-152 ◽  
Author(s):  
M. Tatian ◽  
R.J. Sahade ◽  
M.E. Doucet ◽  
G.B. Esnal
Keyword(s):  
Abundant Species ◽  
South Shetland Islands ◽  
Physical Factors ◽  
Substrate Type ◽  
Patchy Distribution ◽  
Potter Cove ◽  
Shetland Islands ◽  
Soft Bottoms ◽  
Synoicum Adareanum ◽  
Main Factor

Certain physical factors, substrate type and ice action appear to be important determinants for ascidian distribution. Three different substrate types were sampled at depths between 0–30 m by SCUBA diving: soft bottoms, hard bottoms and moraine deposits. The species found were Aplidium radiatum, Synoicum adareanum, Distaplia cylindrica, Sycozoa gaimardi, Sycozoa sigillinoides, Tylobranchion speciosum, Corella eumyota, Ascidia challengeri, Cnemidocarpa verrucosa, Styela wandeli, Dicarpa insinuosa, Pyura bouvetensis, Pyura discoveryi, Pyura obesa, Pyura setosa, Molgula enodis and Molgula pedunculata. Highest diversity and patchy distribution was found in less stringent environments, where epibiosis is a commmon phenomenon on stolidobranch ascidians. Differences in stalk development were found in the most abundant species Molgula pedunculata and Cnemidocarpa verrucosa. Ice action may be the main factor that determines the absence of ascidians above 15 m in all the stations sampled.

Exposure dating of a pronounced glacier advance at the onset of the late-Holocene in the central Tyrolean Alps

The Holocene ◽  
2017 ◽  
Vol 27 (9) ◽  
pp. 1350-1358 ◽  
Author(s):  
Andrew P Moran ◽  
Susan Ivy Ochs ◽  
Marcus Christl ◽  
Hanns Kerschner
Keyword(s):  
Little Ice Age ◽  
Late Holocene ◽  
Ice Age ◽  
Similar Reaction ◽  
Equilibrium Line Altitude ◽  
Alpine Valley ◽  
Modern Times ◽  
Exposure Dating ◽  
Glacier Advance ◽  
Accumulation Area Ratio

A two-phased moraine system in the high Alpine valley of Lisenser Längental in the Stubai Alps of western Austria is located in an intermediate morphostratigraphic position constrained by ‘Egesen Stadial’ (Younger Dryas) moraines down valley and ‘Little Ice Age’ (‘LIA’) positions (modern times) up valley. The equilibrium line altitude (ELA) was about 50 m lower than during the ‘LIA’ when applying an accumulation area ratio of 0.67. Exposure dating of boulders with 10Be yields a mean age of 3750 ± 330 years for the more extensive outer moraine system and a single age of 3140 ± 280 years for the inner one. The ages correspond well to the ‘Loebben oscillation’, a sequence of multi-decadal to multi-centennial cooling phases at the onset of the late-Holocene, also recognized in other Alpine records. The climatic downturn was severe enough to cause small to medium-sized Alpine glaciers in the central Alps to advance significantly beyond their ‘LIA’ extent, but too short to trigger a similar reaction with large glaciers.

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