scholarly journals New geological interpretation of multi-channel seismic profiles from the Pacific Margin of the Antarctic Peninsula

2016 ◽  
Vol 37 (2) ◽  
pp. 243-268 ◽  
Author(s):  
Jan Okoń ◽  
Jerzy Giżejewski ◽  
Tomasz Janik
Keyword(s):  
Accretionary Prism ◽  
South Shetland Islands ◽  
The South ◽  
Seismic Profiles ◽  
Geological Interpretation ◽  
Bransfield Strait ◽  
Time Migration ◽  
The Pacific ◽  
Deep Seismic Soundings ◽  
South Shetland Trench

Abstract The Polish Geophysical Expedition to West Antarctica in 1979–1980 was carried out by the Institute of Geophysics, Polish Academy of Sciences. Beside deep seismic soundings, 12 multi-channel seismic profiles, with a total length of ca 1000 km have been recorded north and east of the South Shetland Islands and in the Bransfield Strait, but they have never before been completely interpreted and published. All profiles have been processed with modern processing flow including time migration. Profiles crossing the South Shetland Trench revealed distinct reflector inside continental slope, which has been interpreted as border between buried accretionary prism and overlying slope sediments of glacial-marine origin. Profiles in the Bransfield Strait show traces of the Last Glacial Maximum (LGM) in the form of glacial foreground valleys, with some of them used as weak spots for young age volcanic intrusions. This paper is the first comprehensive geological interpretation of collected dataset and differences between results from other expeditions are discussed.

scholarly journals SEISMIC CHARACTERISTICS AND SEDIMENTARY DISTRIBUTION ON THE SOUTH SHETLAND ISLANDS CONTINENTAL MARGIN, ANTARCTICA

2014 ◽  
Vol 32 (3) ◽  
pp. 549 ◽  
Author(s):  
Fabio José Guedes Magrani ◽  
Arthur Ayres Neto
Keyword(s):  
High Resolution ◽  
Continental Margin ◽  
South Shetland Islands ◽  
Geological Samples ◽  
The South ◽  
Seismic Profiles ◽  
Shetland Islands ◽  
Bransfield Strait ◽  
Sandy Silt ◽  
Seismic Amplitudes

ABSTRACT. This work consists in characterizing the sedimentary distribution of the South Shetland Islands continental margin, Bransfield Strait, Antarctica, throughthe interpretation and correlation of high-resolution seismic profiles and geological samples. The analysis of echo-characters, seismic amplitudes and their correlationwith the collected samples, revealed five different echo types. Echo types I and II have good seismic resolution and are characterized by continuous sharp bottom echoeswith subparallel reflections. Echoes III and IV are characterized by diffuse and very prolonged bottom echoes with no subbottom reflectors. Echo V is associated withglacial deposits on the upper slope in response to deglaciation and transport of coarse grains in a muddy matrix and is characterized by diffraction hyperbolae. Theecho-characters showed good correlation with geological samples collected along the Bransfield Strait and bays of the King George Island, but the correlation with theseismic amplitude map was not as obvious. Echo I shows medium-high amplitudes and samples within its area of occurrence (AM-02 and AM-14) indicate silty sandand sandy silt, respectively. Echo II presents the lowest seismic amplitudes and the sample collected within its area (AM-17) shows approximately 90% mud content.Echoes III and IV, located on the shallowest portions of South Shetland’s continental margin, demonstrate medium-low amplitude values, and are related to samplesAM-01 and AM-04, both classified as sandy silt with approximately 35%sand.Keywords: Bransfield Strait, echo-characters, high-resolution seismic, sedimentary analysis. RESUMO. O presente trabalho consiste na interpretação integrada da sísmica de alta resolução e da amostragem geológica, a fim de caracterizar a geologia de fundona região da margem continental das Ilhas Shetland do Sul, Estreito de Bransfield, Antártica. A caracterização geológica foi realizada através da análise de ecocaráteres, mapas de amplitude sísmica e sua correlação com os sedimentos coletados. Cinco diferentes ecocaráteres foram identificados e classificados. Ecos I e II demonstramboa resolução e são caracterizados por ecos contínuos e nítidos com reflexões subparalelas. Ecos III e IV são caracterizados por ecos difusos, muito prolongados ecom ausência de refletores subparalelos. O Eco V está associado a depósitos glaciais no talude superior, em respostas ao degelo, e ao transporte de grãos grossos em uma matriz mais fina. Além disso, é caracterizado pela presença de hipérboles de difração. Os ecocaráteres mostraram boa correlação com os testemunhos geológicos coletados no Estreito de Bransfield e nas baías da Ilha Rei George, mas não apresentaram uma relação óbvia com o mapa de amplitudes. O Eco I possui amplitudes médio-altas e as amostras contidas em sua área (AM-02 e AM-14) indicam, respectivamente, um conteúdo de areia siltosa e silte arenoso. O Eco II apresenta os menores valores de amplitude com conteúdo de lama (argila + silte) de aproximadamente 90%, conforme a amostra AM-17. Os Ecos III e IV, localizados nas porções mais rasasda margem continental das Shetland do Sul, demonstram valores médio-baixos de amplitude e se relacionam às amostras AM-01 e AM-04, ambas siltes-arenosos com conteúdo de areia de aproximadamente 35%.Palavras-chave: Estreito de Bransfield, ecocaráteres, sísmica de alta resolução, análise sedimentar.

Chapter 3.2b Bransfield Strait and James Ross Island: petrology

2021 ◽  
pp. M55-2018-37 ◽  
Author(s):  
Karsten M. Haase ◽  
Christoph Beier
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Island ◽  
The South ◽  
Bransfield Strait ◽  
Geodynamic Processes ◽  
James Ross Island ◽  
South Shetland Trench ◽  
Low Degrees ◽  
Back Arc ◽  
The Antarctic

AbstractYoung volcanic centres of the Bransfield Strait and James Ross Island occur along back-arc extensional structures parallel to the South Shetland island arc. Back-arc extension was caused by slab rollback at the South Shetland Trench during the past 4 myr. The variability of lava compositions along the Bransfield Strait results from varying degrees of mantle depletion and input of a slab component. The mantle underneath the Bransfield Strait is heterogeneous on a scale of approximately tens of kilometres with portions in the mantle wedge not affected by slab fluids. Lavas from James Ross Island east of the Antarctic Peninsula differ in composition from those of the Bransfield Strait in that they are alkaline without evidence for a component from a subducted slab. Alkaline lavas from the volcanic centres east of the Antarctic Peninsula imply variably low degrees of partial melting in the presence of residual garnet, suggesting variable thinning of the lithosphere by extension. Magmas in the Bransfield Strait form by relatively high degrees of melting in the shallow mantle, whereas the magmas some 150 km further east form by low degrees of melting deeper in the mantle, reflecting the diversity of mantle geodynamic processes related to subduction along the South Shetland Trench.

scholarly journals Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean

2009 ◽  
Vol 6 (4) ◽  
pp. 7481-7515 ◽  
Author(s):  
M. V. Ardelan ◽  
O. Holm-Hansen ◽  
C. D. Hewes ◽  
C. S. Reiss ◽  
N. S. Silva ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Weddell Sea ◽  
South Shetland Islands ◽  
The South ◽  
Total Acid ◽  
Shetland Islands ◽  
Iron Enrichment ◽  
Bransfield Strait ◽  
Natural Iron ◽  
The Antarctic

Abstract. As part of the US-AMLR program that occupied 99 hydrographic stations in the South Shetland Islands-Antarctic Peninsula region in January–February of 2006, concentrations of dissolved iron (DFe) and total acid-leachable iron (TaLFe) were measured in the upper 150 m at 16 stations (both coastal and pelagic waters). The concentrations in the upper mixed layer (UML) of DFe and TaLFe were relatively high in Weddell Sea Shelf Waters (~0.6 nM and 15 nM, respectively) and lowest in Drake Passage waters (~0.2 nM and 0.9 nM, respectively). In the Bransfield Strait, representing a mixture of waters from the Weddell Sea and the Antarctic Circumpolar Current (ACC), concentrations of DFe were ~0.4 nM and of TaLFe ~1.7 nM. The highest concentrations of DFe and TaLFe in the UML were found at shallow coastal stations close to Livingston Island (~1.6 nM and 100 nM, respectively). The ratio of TaLFe:DFe varied with the distance to land: ~45 at the shallow coastal stations, ~15 in the high-salinity waters of Bransfield Strait, and ~4 in ACC waters. Concentrations of DFe increased slightly with depth in the water column, while that of TaLFe did not show any consistent trend with depth. Our data are consistent with the hypothesis that the relatively high rates of primary production known from the central regions of the Scotia Sea are partially sustained by natural iron enrichment resulting from a northeasterly flow of iron-rich coastal waters originating in the South Shetland Islands-Antarctic Peninsula region.

Two new species of Dorymenia (Mollusca: Solenogastres: Proneomeniidae) from the South Shetland Islands (Antarctica)

2000 ◽  
Vol 80 (5) ◽  
pp. 835-842 ◽  
Author(s):  
O. García-Alvarez ◽  
V. Urgorri ◽  
L. von Salvini-Plawen
Keyword(s):  
New Species ◽  
Comparative Study ◽  
South Shetland Islands ◽  
The South ◽  
Shetland Islands ◽  
Bransfield Strait ◽  
Livingston Island ◽  
Two New Species ◽  
Antarctic Benthos

This paper describes two new species from the genus Dorymenia (Mollusca: Solenogastres: Proneomeniidae): D. hesperidesi sp. nov. and D. menchuescribanae sp. nov., collected during the Spanish oceanographic expeditions for the study of Antarctic benthos, BENTART'94 and BENTART'95, carried out in the area of the Livingston Island (South Shetland Islands, Antarctica). A comparative study of main specific characteristics of species belonging to the genus Dorymenia found off the South Shetland Islands and in the Bransfield Strait (Antarctica), is also included.

scholarly journals Seismicity and tectonics of the South Shetland Islands and Bransfield Strait from a regional broadband seismograph deployment

2003 ◽  
Vol 108 (B10) ◽  
Author(s):  
Stacey D. Robertson Maurice ◽  
Douglas A. Wiens ◽  
Patrick J. Shore ◽  
Emilio Vera ◽  
LeRoy M. Dorman
Keyword(s):  
South Shetland Islands ◽  
The South ◽  
Shetland Islands ◽  
Bransfield Strait ◽  
Seismicity And Tectonics
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