The role of crustal and mantle sources in the genesis of granitoids of the Antarctic Peninsula and adjacent crustal blocks

2001 ◽  
Vol 158 (5) ◽  
pp. 855-867 ◽  
Author(s):  
I. L. MILLAR ◽  
R. C. R. WILLAN ◽  
C. D. WAREHAM ◽  
A. J. BOYCE
Keyword(s):  
Antarctic Peninsula ◽  
Mantle Sources ◽  
The Antarctic

The role of fish in the Antarctic marine food web: differences between inshore and offshore waters in the southern Scotia Arc and west Antarctic Peninsula

2002 ◽  
Vol 14 (4) ◽  
pp. 293-309 ◽  
Author(s):  
ESTEBAN BARRERA-ORO
Keyword(s):  
Food Web ◽  
Antarctic Peninsula ◽  
Demersal Fish ◽  
Pelagic Fish ◽  
West Antarctic ◽  
Antarctic Marine ◽  
Scotia Arc ◽  
West Antarctic Peninsula ◽  
The Antarctic

The role of fish in the Antarctic food web in inshore and offshore waters is analysed, taking as an example the coastal marine communities of the southern Scotia Arc (South Orkney Islands and South Shetland Islands) and the west Antarctic Peninsula. Inshore, the ecological role of demersal fish is more important than that of krill. There, demersal fish are major consumers of benthos and also feed on zooplankton (mainly krill in summer). They are links between lower and upper levels of the food web and are common prey of other fish, birds and seals. Offshore, demersal fish depend less on benthos and feed more on zooplankton (mainly krill) and nekton, and are less accessible as prey of birds and seals. There, pelagic fish (especially lantern fish) are more abundant than inshore and play an important role in the energy flow from macrozooplankton to higher trophic levels (seabirds and seals). Through the higher fish predators, energy is transferred to land in the form of fish remains, pellets (birds), regurgitation and faeces (birds and seals). However, in the general context of the Antarctic marine ecosystem, krill (Euphausia superba) plays the central role in the food web because it is the main food source in terms of biomass for most of the high level predators from demersal fish up to whales. This has no obvious equivalent in other marine ecosystems. In Antarctic offshore coastal and oceanic waters the greatest proportion of energy from the ecosystem is transferred to land directly through krill consumers, such as flying birds, penguins, and seals. Beside krill, the populations of fish in the Antarctic Ocean are the second most important element for higher predators, in particular the energy-rich pelagic Myctophidae in open waters and the pelagic Antarctic silver fish (Pleuragramma antarcticum) in the high Antarctic zone. Although the occurrence of these pelagic fish inshore has been poorly documented, their abundance in neritic waters could be higher than previously believed.

Isotope evidence for the origin of Andean granites

1988 ◽  
Vol 79 (2-3) ◽  
pp. 123-133 ◽  
Author(s):  
R. J. Pankhurst ◽  
M. J. Hole ◽  
M. Brook
Keyword(s):  
Antarctic Peninsula ◽  
Nd Isotope ◽  
Depleted Mantle ◽  
Wide Range ◽  
Mantle Sources ◽  
Subducted Oceanic Crust ◽  
Isotope Evidence ◽  
The Antarctic ◽  
Isotope Systematics ◽  
Material Input

ABSTRACTThe genesis of subduction-related magmas in the Andean region of South America and the Antarctic Peninsula is considered in relation to the Palaeozoic to Cenozoic granitoids belts which are thought to parallel palaeo-coastlines. Their Sr-Nd isotope systematics show a wide range of initial compositions (87Sr/86Sr0 0·7038 to >0·710; εNd, +4 to –10) requiring material input from both depleted mantle and continental crust. In local transects there are consistent trends with time of emplacement, from enriched (crustal) to depleted (mantle) sources, regardless of the sense of migration of magmatism (towards or away from the continent). These trends represent mixing between mantle-derived material and anatectic melts of the lower crust: in each case the crustal end-member reflects the age and isotopic composition of the local deep crustal basement (Precambrian in the easternmost Andes, Palaeozoic in the W and in the Antarctic Peninsula). The depleted end-member could be derived by melting within the subducted oceanic crust, the overlying mantle or previously crystallised mafic underplating. One of the most important factors controlling the mixing process is the angle of subduction, resulting in magma generation under variable tectonic conditions.

scholarly journals Analysis of Antarctic Peninsula glacier frontal ablation rates with respect to iceberg melt-inferred variability in ocean conditions

2020 ◽  
Vol 66 (257) ◽  
pp. 457-470
Author(s):  
M. C. Dryak ◽  
E. M. Enderlin
Keyword(s):  
Antarctic Peninsula ◽  
Ocean Warming ◽  
Ice Shelf ◽  
The West ◽  
Temperature Variations ◽  
Frontal Dynamics ◽  
Ocean Conditions ◽  
The Antarctic ◽  
Frontal Ablation

AbstractMarine-terminating glaciers on the Antarctic Peninsula (AP) have retreated, accelerated and thinned in response to climate change in recent decades. Ocean warming has been implicated as a trigger for these changes in glacier dynamics, yet little data exist near glacier termini to assess the role of ocean warming here. We use remotely-sensed iceberg melt rates seaward of two glaciers on the eastern and six glaciers on the western AP from 2013 to 2019 to explore connections between variations in ocean conditions and glacier frontal ablation. We find iceberg melt rates follow regional ocean temperature variations, with the highest melt rates (mean ≈ 10 cm d−1) at Cadman and Widdowson glaciers in the west and the lowest melt rates (mean ≈ 0.5 cm d−1) at Crane Glacier in the east. Near-coincident glacier frontal ablation rates from 2014 to 2018 vary from ~450 m a−1 at Edgeworth and Blanchard glaciers to ~3000 m a−1 at Seller Glacier, former Wordie Ice Shelf tributary. Variations in iceberg melt rates and glacier frontal ablation rates are significantly positively correlated around the AP (Spearman's ρ = 0.71, p-value = 0.003). We interpret this correlation as support for previous research suggesting submarine melting of glacier termini exerts control on glacier frontal dynamics around the AP.

The role of organic ligands in iron cycling and primary productivity in the Antarctic Peninsula: A modeling study

2013 ◽  
Vol 90 ◽  
pp. 112-133 ◽  
Author(s):  
Mingshun Jiang ◽  
Katherine A. Barbeau ◽  
Karen E. Selph ◽  
Christopher I. Measures ◽  
Kristen N. Buck ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Primary Productivity ◽  
Organic Ligands ◽  
Iron Cycling ◽  
The Antarctic ◽  
Modeling Study

Atmospheric rivers landfalling at the Antarctic Peninsula: the Year of Polar Prediction summer special observing period measurements for model and forecast improvement 

2021 ◽  
Author(s):  
Irina Gorodetskaya ◽  
Penny Rowe ◽  
Heike Kalesse ◽  
Patric Seifert ◽  
Sang-Jong Park ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Antarctic Peninsula ◽  
Moisture Transport ◽  
Radiative Forcing ◽  
Snow Accumulation ◽  
Added Value ◽  
Atmospheric Rivers ◽  
Surface Melt ◽  
The Antarctic

<p>During the last several decades, the Antarctic Peninsula (AP) has shown a much stronger warming trend compared to the rest of the ice sheet and other land areas in the Southern Hemisphere (Jones et al, 2019). Recent studies have also highlighted that the AP has experienced both an increase in precipitation and in surface melt. Atmospheric rivers (ARs) – long corridors of intense moisture transport from subtropical and mid-latitude regions poleward - are known for prominent role in moisture transport (Gorodetskaya et al, 2020) and intense precipitation in Antarctica (Gorodetskaya et al 2014). At the same time, ARs have been also associated with major surface melt events at the AP and adjacent ice shelves (Wille et al 2019). In this study, we explore the double role of ARs, as carriers of both heat and moisture, in their impacts on precipitation (rain and snow), cloud radiative forcing and air temperature at the AP. Observations from the Year of Polar Prediction (YOPP, Bromwich et al 2020) endorsed sites/projects are used: Escudero station (the Characterization of the Antarctic Atmosphere and Low Clouds, or CAALC project) and King Sejong station (South Korean Antarctic Program projects) on King George Island, as well as Punta Arenas (southern Chile; the Dynamics, Aerosol, Cloud, And Precipitation Observations in the Pristine Environment of the Southern Ocean, or DACAPO-PESO project). These projects employed a set of ground-based remote sensing instrumentation for water vapor, cloud and precipitation observations, as well as frequent radiosonde launches during the YOPP Special Observing Period in austral summer 2018/2019. We present case studies characterizing the temporal evolution of ARs, focusing on thermodynamic and dynamic conditions accompanying the transition between snowfall and rain. Further, we demonstrate the added value of assimilating more frequent radiosonde observations in improving the forecast of weather conditions during ARs using the Polar-WRF model, including wind and precipitation prediction, which have important consequences for air, ship and station operations in Antarctica.</p><p>Bromwich, D. H., K. Werner, B. Casati, J. G. Powers, I. V. Gorodetskaya, F. Massonnet, V. Vitale, et al: The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH), Bull. Amer. Meteor. Soc., doi: https://doi.org/10.1175/BAMS-D-19-0255.1.</p><p>Gorodetskaya, I.V., Silva, T., Schmithüsen, H., and Hirasawa, N., 2020: Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica.Adv. Atmos. Sci., https://doi.org/10.1007/s00376-020-9221-8</p><p>Gorodetskaya, I. V., M. Tsukernik, K. Claes, M. F. Ralph, W. D. Neff, and N. P. M. van Lipzig, 2014: The role of atmospheric rivers in anomalous snow accumulation in East Antarctica. Geophys. Res. Lett.,  https://doi.org/10.1002/2014GL060881</p><p>Jones, M. E., Bromwich, D. H., Nicolas, J. P., Carrasco, J., Plavcova, E., Zou, X., & Wang, A. S.-H. (2019). Sixty Years of Widespread Warming in the Southern Middle and High Latitudes (1957-2016). J. Climate, https://doi.org/10.1175/JCLI-D-18</p><p>Wille, J.D., Favier, V., Dufour, A., Gorodetskaya, I.V., Turner, J., Agosta, C., and Codron, F., 2019. West Antarctic surface melt triggered by atmospheric rivers. Nat. Geosci. https://doi.org/10.1038/s41561-019-0460-1</p>

scholarly journals Gene flow in the Antarctic bivalve Aequiyoldia eightsii (Jay, 1839) suggests a role for the Antarctic Peninsula Coastal Current in larval dispersal

2020 ◽  
Vol 7 (9) ◽  
pp. 200603
Author(s):  
Carlos P. Muñoz-Ramírez ◽  
David K. A. Barnes ◽  
Leyla Cárdenas ◽  
Michael P. Meredith ◽  
Simon A. Morley ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Antarctic Peninsula ◽  
Ocean Circulation ◽  
Genomic Data ◽  
Coastal Current ◽  
Species Dispersal ◽  
Southern South America ◽  
Migration Rates ◽  
The Antarctic

The Antarctic Circumpolar Current (ACC) dominates the open-ocean circulation of the Southern Ocean, and both isolates and connects the Southern Ocean biodiversity. However, the impact on biological processes of other Southern Ocean currents is less clear. Adjacent to the West Antarctic Peninsula (WAP), the ACC flows offshore in a northeastward direction, whereas the Antarctic Peninsula Coastal Current (APCC) follows a complex circulation pattern along the coast, with topographically influenced deflections depending on the area. Using genomic data, we estimated genetic structure and migration rates between populations of the benthic bivalve Aequiyoldia eightsii from the shallows of southern South America and the WAP to test the role of the ACC and the APCC in its dispersal. We found strong genetic structure across the ACC (between southern South America and Antarctica) and moderate structure between populations of the WAP. Migration rates along the WAP were consistent with the APCC being important for species dispersal. Along with supporting current knowledge about ocean circulation models at the WAP, migration from the tip of the Antarctic Peninsula to the Bellingshausen Sea highlights the complexities of Southern Ocean circulation. This study provides novel biological evidence of a role of the APCC as a driver of species dispersal and highlights the power of genomic data for aiding in the understanding of the influence of complex oceanographic processes in shaping the population structure of marine species.

Southern high latitude vegetation change across the Drake Passage region linked to prolonged intervals of climate cooling during the early Oligocene

2021 ◽  
Author(s):  
Nick Thompson ◽  
Ulrich Salzmann ◽  
Adrián López Quirós ◽  
Carlota Escutia ◽  
Peter Bijl ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Vegetation Change ◽  
Drake Passage ◽  
Late Eocene ◽  
Mean Annual Temperature ◽  
Temperature And Precipitation ◽  
Early Oligocene ◽  
Terrestrial Environments ◽  
The Antarctic

<p>The possible causes of the onset of Antarctic glaciation around the Eocene-Oligocene Transition (EOT), approximately 34 million years ago (~34Ma), are poorly understood. Uncertainties particularly remain over the role of the Drake Passage opening on the development of the Antarctic Circumpolar Current (ACC), and how this affected both marine and terrestrial environments. A major obstacle in understanding the role of the opening Drake Passage and ACC in Cenozoic climate changes has been the lack of continuous records spanning the EOT from the region. Here we present new palynomorph data from ODP Leg 113 Site 696 Hole B, recording changes in terrestrial environments and paleoclimate across the EOT. The sporomorph assemblage reveals the presence of Nothofagus-dominated forests with secondary Podocarpaceae and an understory of angiosperms and cryptogams growing across much of the Northern Antarctic Peninsula and South Orkney Microcontinent during the late Eocene (~37.60-34.95 Ma). Palaeoclimate reconstructions show that these forests grew under wet temperate conditions, with mean annual temperature and precipitation around 12°C and 1650mm, respectively. Today, similar temperate Nothofagus-dominated mixed-podocarp forests occur in the temperate Valdivian region of southern Chile. At the onset of the EOT, the palynomorph assemblage indicates an unusual expansion of gymnosperms and cryptogams, accompanied by a rapid increase in taxa diversity between ca. 34 and 32 Ma. Sporomorph based climate reconstructions do not provide evidence for an abrupt cooling at the EOT but reveal the onset of prolonged cooling phases throughout the early Oligocene. A contemporaneous increase in reworked Mesozoic sporomorphs at the EOT is likely to be linked to frequent glacial advances from the Antarctic Peninsula and South Orkney Microcontinent, although iceberg-rafted debris from Antarctica cannot be ruled out. We conclude that climate instability and glacial related disturbance at the onset of the EOT facilitated the suppression of Nothofagus and the expansion of a more diverse vegetation with many pioneer taxa that were able to quickly colonise during glacial retreat cycles.</p>

scholarly journals Stratigraphic Analysis of Firn Cores from an Antarctic Ice Shelf Firn Aquifer

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 731
Author(s):  
Shelley MacDonell ◽  
Francisco Fernandoy ◽  
Paula Villar ◽  
Arno Hammann
Keyword(s):  
Antarctic Peninsula ◽  
Field Measurements ◽  
Field Observations ◽  
Ice Shelf ◽  
New Classification ◽  
Ice Shelves ◽  
Stratigraphic Analysis ◽  
Modelling Studies ◽  
The Antarctic

In recent decades, several large ice shelves in the Antarctic Peninsula region have experienced significant ice loss, likely driven by a combination of oceanic, atmospheric and hydrological processes. All three areas need further research, however, in the case of the role of liquid water the first concern is to address the paucity of field measurements. Despite this shortage of field observations, several authors have proposed the existence of firn aquifers on Antarctic ice shelves, however little is known about their distribution, formation, extension and role in ice shelf mechanics. In this study we present the discovery of saturated firn at three drill sites on the Müller Ice Shelf (67°14′ S; 66°52′ W), which leads us to conclude that either a large contiguous or several disconnected smaller firn aquifers exist on this ice shelf. From the stratigraphic analysis of three short firn cores extracted during February 2019 we describe a new classification system to identify the structures and morphological signatures of refrozen meltwater, identify evidence of superficial meltwater percolation, and use this information to propose a conceptual model of firn aquifer development on the Müller Ice Shelf. The detailed stratigraphic analysis of the sampled cores will provide an invaluable baseline for modelling studies.

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