scholarly journals Pre-glacial sedimentary facies of the Point Thomas Formation (Eocene) at Cytadela, Admiralty Bay, King George Island, West Antarctica

2012 ◽  
Vol 33 (1) ◽  
pp. 41-62 ◽  
Author(s):  
Anna Mozer
Keyword(s):  
Chemical Weathering ◽  
Sedimentary Facies ◽  
Climatic Conditions ◽  
South Shetland Islands ◽  
Terrestrial Vegetation ◽  
King George Island ◽  
West Antarctica ◽  
Humid Climate ◽  
Climate Conditions ◽  
Admiralty Bay

Pre-glacial sedimentary facies of the Point Thomas Formation (Eocene) at Cytadela, Admiralty Bay, King George Island, West Antarctica New evidence of Eocene preglacial environments has been found on the southern coast of Ezcurra Inlet on King George Island, South Shetland Islands, West Antarctica. Plant remains (trunks, leaves, detritus) and carbonaceous seams and beds occur in sedimentary strata in a 4 km long Cytadela outcrop of the Point Thomas Formation. They are an evidence for the presence and diversity of terrestrial vegetation in the northern Antarctic Peninsula region. The forests were composed mostly of Podocarpaceae-Araucaria-Nothofagus, with an undergrowth of hygrophilous and thermophilous ferns, and grew on volcanic slopes and surrounding lowland areas of King George Island during breaks in volcanic activity. The succession that crops out at Cytadela provides a record of changing climatic conditions from a warm and wet climate with extensive vegetation to a much drier climate with limited vegetation and ubiquitous weathering of volcanic bedrock. The geochemical indices of weathering (CIA, PIA and CIW) have narrow and relatively high value ranges (76-88), suggesting moderate to high chemical weathering under warm and humid climate conditions. The decrease in humidity and the decline in plant life through the succession can be related to the gradually cooling climate preceding development of the Oligocene ice cover across the Antarctic continent.

A new Antarctic foraminiferal species for detecting climate change in sub-Recent glacier-proximal sediments

2009 ◽  
Vol 21 (5) ◽  
pp. 439-448 ◽  
Author(s):  
Wojciech Majewski ◽  
Andrzej Tatur
Keyword(s):  
Climate Change ◽  
Climate Warming ◽  
The Arctic ◽  
South Shetland Islands ◽  
King George Island ◽  
Tidewater Glaciers ◽  
Admiralty Bay ◽  
Shetland Islands ◽  
Foraminiferal Species ◽  
Water Depths

AbstractCribroelphidium webbi sp. nov. is the only adequately described sub-Recent elphidiid foraminifer from Antarctica. In Admiralty Bay (King George Island, South Shetland Islands), it is found at several locations within inner fiord setting at water depths between 33 and 165 m, but most commonly shallower than 100 m. In outer basins this foraminifer is absent. In the cores analysed, C. webbi sp. nov. is present in well-constrained sub-Recent horizons that are clearly related to climate warming and deglaciation. These horizons represent a diachronous facies marker rather than a single stratigraphic layer. Cribroelphidium webbi sp. nov. shows clear association with retreating tidewater glaciers, therefore it is an important sensitive glacier-proximal indicator. It appears that it shares similar ecologic affinities with Cribroelphidium excavatum clavatum, which is widely distributed throughout the Arctic.

scholarly journals New records of isopod species of the Antarctic Specially Managed Area No. 1, Admiralty Bay, South Shetland Islands

2017 ◽  
Vol 38 (3) ◽  
pp. 409-419
Author(s):  
Karol Zemko ◽  
Krzysztof Pabis ◽  
Jacek Siciński ◽  
Magdalena Błażewicz
Keyword(s):  
Southern Ocean ◽  
New Records ◽  
South Shetland Islands ◽  
Small Scale ◽  
King George Island ◽  
Admiralty Bay ◽  
Shetland Islands ◽  
The Antarctic ◽  
First Time ◽  
Marine Basins

AbstractAdmiralty Bay (King George Island) is an Antarctic Specially Managed Area and one the most thoroughly studied small-scale marine basins in the Southern Ocean. Our study provides new data on the isopod fauna in this glacially affected fjord. Twelve species of isopods were recorded in this basin for the first time. Six of them were found for the first time in the region of the South Shetland Islands. The highest number of species new for Admiralty Bay were found in the families Munnopsidae (4 species) and Munnidae (3 species).

scholarly journals Dynamics of the ice cap on King George Island, Antarctica: field measurements and numerical simulations

2010 ◽  
Vol 51 (55) ◽  
pp. 80-90 ◽  
Author(s):  
Martin Rückamp ◽  
Norbert Blindow ◽  
Sonja Suckro ◽  
Matthias Braun ◽  
Angelika Humbert
Keyword(s):  
Air Temperature ◽  
Water Layer ◽  
Climatic Conditions ◽  
King George Island ◽  
Differential Gps ◽  
Ice Flow ◽  
Climate Conditions ◽  
Ice Cap ◽  
Ice Surface ◽  
Mean Annual Air Temperature

AbstractKing George Island is located at the northern tip of the Antarctic Peninsula, which is influenced by maritime climate conditions. The observed mean annual air temperature at sea level is –2.4˚C. Thus, the ice cap is regarded as sensitive to changing climatic conditions. Ground-penetrating radar surveys indicate a partly temperate ice cap with an extended water layer at the firn/ice transition of the up to 700 m high ice cap. Measured firn temperatures are close to 0˚C at the higher elevations, and they differ considerably from the measured mean annual air temperature. The aim of this paper is to present ice-flow dynamics by means of observations and simulations of the flow velocities. During several field campaigns from 1997/98 to 2008/09, ice surface velocities were derived with repeated differential GPS measurements. Ice velocities vary from 0.7 m a−1 at the dome to 112.1 m a−1 along steep slopes. For the western part of the ice cap a three-dimensional diagnostic full-Stokes model was applied to calculate ice flow. Parameters of the numerical model were identified with respect to measured ice surface velocities. The simulations indicate cold ice at higher elevations, while temperate ice at lower elevations is consistent with the observations.

scholarly journals Pedogenic and subaerial exposure microfabrics in a late Carboniferous-early Permian carbonate-volcanic lacustrine-palustrine system (San Ignacio Formation, Frontal Cordillera, Argentina)

2020 ◽  
Vol 47 (2) ◽  
pp. 275
Author(s):  
Isabel Méndez-Bedia ◽  
Gloria Gallastegui ◽  
Pedro Busquets ◽  
Silvia N. Césari ◽  
Carlos O. Limarino ◽  
...  
Keyword(s):  
Wide Spectrum ◽  
Volcanic Rocks ◽  
Climatic Conditions ◽  
Late Carboniferous ◽  
Early Permian ◽  
Humid Climate ◽  
Climate Conditions ◽  
Subaerial Exposure ◽  
Drying Conditions ◽  
Micro Organisms

In the Argentinian Andes (Frontal Cordillera) the upper part of the late Carboniferous-early Permian San Ignacio Formation is made up of lacustrine-palustrine microbial carbonates and interbedded volcanic deposits. In this lacustrine-palustrine environment a natural monospecific forest was developed. The deposits of this sedimentary-volcanic succession were repeatedly subjected to subaerial exposure and modified by pedogenesis to varying degrees giving rise to paleosoils development. Diagenetic microfabrics were well preserved in the carbonates and volcanic rocks. The carbonate microfabrics comprise a wide spectrum of features consisting of root marks and stumps-related structures (rhizoliths, alveolar texture, tunnel-like structures and coprolites of arthropods), pisoids, coated grains and pseudomicrokarst, cracking, brecciated and nodular fabrics, and grainification also occur corresponding to different stages in the pedogenic evolution. Meteoric dissolution and cementation processes are observed; examples are well identified by scanning electron microscope showing silica-filled voids in partially dissolved carbonates and growths of inorganic carbonate microcrystals or of microbial origin in voids. Other different types of cements can be seen such as discontinuous carbonate crusts, ribbon spar, cavities with silt infillings and pendant cements. The whole set of these microfabrics are indicative of wetting, desiccation and meteoric conditions (vadose and phreatic). The abundance of plant roots and associated micro-organisms mainly of bacterial origin (micro-rods, short rod-shapes, nano-fibres, filaments and nano-spheres) played an important role in the pedogenic and subaerial diagenetic processes affecting these deposits. The immature character of the paleosoils and absence of calcretes point out to short intervals of subaerial exposure due to oscillating fluctuations in water level, intermittent volcanic supply, tectonic subsidence and oscillating climatic conditions. The whole of the macro and microfabrics reveals that the prevailing weather could correspond to an intermediate between semi-arid to sub-humid, however the alternating wetting and drying conditions in which the fossil forest developed and the abundance and diversity of micro-organisms, suggest a transition to sub-humid climate conditions.

scholarly journals Geographical Research of the 30th Polish Antarctic Expedition at Arctowski Polish Station (King George Island, South Shetland Islands, Antarctica)

2008 ◽  
Vol 13 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Piotr Angiel
Keyword(s):  
Environmental Conditions ◽  
South Shetland Islands ◽  
King George Island ◽  
Aeolian Transport ◽  
Admiralty Bay ◽  
Shetland Islands ◽  
Geographical Research ◽  
Outwash Plain ◽  
Antarctic Expedition ◽  
Quartz Grains

Abstract This paper presents the scope of geographical research conducted at Arctowski Station during the 30th Polish Antarctic Expedition. The research included meteorological, climatological, geomorphological and glaciological issues. During the expedition, research was conducted on sandur sediments on the outwash plain of Sphinx Glacier, the size of the aeolian transport, intensity of periglacial phenomena, and the way in which environmental conditions are recorded on quartz grains collected on the Admiralty Bay beaches. Detailed measurements of the basic meteorological components were made, geomorphological maps of the outwash plains of Sphinx, Baranowski, and Windy Glaciers were also completed.

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