Electron microprobe characterization of ash layers in sediments from the central Bransfield basin (Antarctic Peninsula): evidence for at least two volcanic sources

2002 ◽  
Vol 14 (4) ◽  
pp. 412-421 ◽  
Author(s):  
S. FRETZDORFF ◽  
J.L. SMELLIE
Keyword(s):  
Antarctic Peninsula ◽  
Hydrothermal Activity ◽  
South Shetland Islands ◽  
Deception Island ◽  
Scotia Sea ◽  
Bransfield Strait ◽  
Sediment Types ◽  
Ash Layer ◽  
Uppermost Layer ◽  
Bransfield Basin

Bransfield Strait, a narrow active rift with three submarine basins, separates the South Shetland Islands from northern Antarctic Peninsula. Volcanism in Bransfield Strait commenced prior to 0.75 Ma and continues, with recent subaerial eruptions at Deception, Bridgeman and Penguin islands, submarine hydrothermal activity and numerous young basaltic seamounts located along the rift axis. Gravity cores were collected from five locations within the central Bransfield basin. Diatomaceous mud interbedded with terrigenous detritus and discrete ash layers up to 10 cm thick are the commonest sediment types in all the cores. The major element compositions of glass shards within the ash layers are, apart from the uppermost layer, compositionally similar to pyroclastic units preserved on Deception Island, a young (<0.75 Ma) active stratovolcano. The uppermost ash layer cannot be closely matched compositionally to any known source in the Antarctic–Scotia Sea–southern South America region. Its presence indicates that a volcanic centre other than Deception Island contributed ash to the Bransfield basin. Based on the shallow stratigraphical position of the compositionally distinctive ash layer, only a few decimetres beneath the seafloor, its source volcano was probably active in historical times (<few hundred years).

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

2010 ◽  
Vol 7 (1) ◽  
pp. 11-25 ◽  
Author(s):  
M. V. Ardelan ◽  
O. Holm-Hansen ◽  
C. D. Hewes ◽  
C. S. Reiss ◽  
N. S. Silva ◽  
...  
Keyword(s):  
Primary Production ◽  
Antarctic Peninsula ◽  
Weddell Sea ◽  
South Shetland Islands ◽  
Scotia Sea ◽  
Shetland Islands ◽  
Iron Enrichment ◽  
Bransfield Strait ◽  
Natural Iron ◽  
The Antarctic

Abstract. As part of the US-AMLR program in January-February of 2006, 99 stations in the South Shetland Islands-Antarctic Peninsula region were sampled to understand the variability in hydrographic and biological properties related to the abundance and distribution of krill in this area. Concentrations of dissolved iron (DFe) and total acid-leachable iron (TaLFe) were measured in the upper 150 m at 16 of these stations (both coastal and pelagic waters) to better resolve the factors limiting primary production in this area and in downstream waters of the Scotia Sea. The concentrations of DFe and TaLFe in the upper mixed layer (UML) were relatively high in Weddell Sea Shelf Waters (~0.6 nM and 15 nM, respectively) and low 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 Fe data are discussed in regard to the hydrography and water circulation patterns in the study area, and with the hypothesis that the relatively high rates of primary production in 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.

Geodynamic implications of the Cenozoic stress field on Seymour Island, West Antarctica

2008 ◽  
Vol 20 (2) ◽  
pp. 173-184 ◽  
Author(s):  
A. Maestro ◽  
J. López-Martínez ◽  
F. Bohoyo ◽  
M. Montes ◽  
F. Nozal ◽  
...  
Keyword(s):  
Stress Field ◽  
Antarctic Peninsula ◽  
Horizontal Stress ◽  
Weddell Sea ◽  
Scotia Sea ◽  
Compressional Stress ◽  
The North ◽  
Stress States ◽  
Bransfield Basin ◽  
Minimum Horizontal Stress

AbstractPalaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ3) orientations are scattered about two main NE–SW and NW–SE modes suggesting that two stress sources have been responsible for the dominant minimum horizontal stress directions in the north-western Weddell Sea. Extensional structures within a broad-scale compressional stress field can be linked to both the decrease in relative stress magnitudes from active margins to intraplate regions and the rifting processes that occurred in the northern Weddell Sea. Stress states with NW–SE trending σ3are compatible with back-arc extension along the eastern Antarctic Peninsula. We interpret this as due to the opening of the Larsen Basin during upper Cretaceous to Eocene and to the spreading, from Pliocene to present, of the Bransfield Basin (western Antarctic Peninsula), both due to former Phoenix Plate subduction under the Antarctic Plate. NE–SW σ3orientations could be expressions of continental fragmentation of the northern Antarctic Peninsula controlling eastwards drifting of the South Orkney microcontinent and other submerged continental blocks of the southern Scotia Sea.

Geotectonic evolution of the Bransfield Basin, Antarctic Peninsula: insights from analogue models

2008 ◽  
Vol 20 (2) ◽  
pp. 185-196 ◽  
Author(s):  
M.A. Solari ◽  
F. Hervé ◽  
J. Martinod ◽  
J.P. Le Roux ◽  
L.E. Ramírez ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Islands ◽  
The South ◽  
The West ◽  
Shetland Islands ◽  
Scotia Ridge ◽  
The North ◽  
Analogue Models ◽  
Bransfield Basin ◽  
The Phoenix

AbstractThe Bransfield Strait, located between the South Shetland Islands and the north-western end of the Antarctic Peninsula, is a back-arc basin transitional between rifting and spreading. We compiled a geomorphological structural map of the Bransfield Basin combining published data and the interpretation of bathymetric images. Several analogue experiments reproducing the interaction between the Scotia, Antarctic, and Phoenix plates were carried out. The fault configuration observed in the geomorphological structural map was well reproduced by one of these analogue models. The results suggest the establishment of a transpressional regime to the west of the southern segment of the Shackleton Fracture Zone and a transtensional regime to the south-west of the South Scotia Ridge by at least c. 7 Ma. A probable mechanism for the opening of the Bransfield Basin requires two processes: 1) Significant transtensional effects in the Bransfield Basin caused by the configuration and drift vector of the Scotia Plate after the activity of the West Scotia Ridge ceased at c. 7 Ma. 2) Roll-back of the Phoenix Plate under the South Shetland Islands after cessation of spreading activity of the Phoenix Ridge at 3.3 ± 0.2 Ma, causing the north-westward migration of the South Shetland Trench.

Bathymetric constraints on the tectonic and volcanic evolution of Deception Island Volcano, South Shetland Islands

2008 ◽  
Vol 21 (2) ◽  
pp. 153-167 ◽  
Author(s):  
A.H. Barclay ◽  
W.S.D. Wilcock ◽  
J.M. Ibáñez
Keyword(s):  
Sediment Supply ◽  
South Shetland Islands ◽  
Caldera Collapse ◽  
Deception Island ◽  
East Side ◽  
Local Effects ◽  
Shetland Islands ◽  
Tectonic Development ◽  
Bransfield Basin ◽  
Regional Tectonics

AbstractDeception Island is the largest volcano in the actively extending Bransfield Basin, a marginal basin situated behind the extinct South Shetland Islands arc. Deception Island has been well studied but its submerged flanks have not. A multibeam bathymetry survey was conducted around the island in 2005. Data from the flooded caldera show no evidence for recent localized resurgence. The gently-sloped bottom of the caldera basin is consistent with either a broad zone of resurgence on its east side associated with trap door deformation or with higher rates of sediment supply from the east side of the island. Around the island, numerous tectonic and volcanic features on the volcano's east and west flanks are nearly all aligned with the regional strike (~060°) of the Bransfield rift and there is very little evidence for the other fault populations that have been identified on the island. We infer that models that link the ongoing tectonic development of Deception Island to complex regional tectonics are less likely than models in which the dominant regional extension in Bransfield Strait is modulated by the local effects of caldera collapse and possibly a small right-lateral transfer zone offsetting the primary extension axes in the Central and Western Bransfield Basins.

scholarly journals Kinematics and segmentation of the South Shetland Islands-Bransfield basin system, northern Antarctic Peninsula

2008 ◽  
Vol 9 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Frederick W. Taylor ◽  
Michael G. Bevis ◽  
Ian W. D. Dalziel ◽  
Robert Smalley ◽  
Cliff Frohlich ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Islands ◽  
The South ◽  
Shetland Islands ◽  
Bransfield Basin ◽  
Basin System

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.

scholarly journals CO1 Metabarcoding of Marine Water Samples from the 2nd Turkish Antarctic Expedition (TAE2) Highlights the Deficiencies in the Reference Barcoding Databases for the Continent

2021 ◽  
Vol 4 ◽  
Author(s):  
Rasit Bilgin ◽  
Kübra Karaman ◽  
Yağmur Tarhana ◽  
Ceylan Yücel ◽  
Elizabeth Hemond ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Methodological Issue ◽  
Demersal Fish ◽  
The Other ◽  
South Shetland Islands ◽  
Marine Biodiversity ◽  
Climate Projections ◽  
Deception Island ◽  
Percent Identity ◽  
The Antarctic

Based on climate projections, the Antarctic Peninsula is one of the regions on the earth expected to be most drastically affected by climate change in the 2nd half of the 21st century. In order to establish baseline levels of marine biodiversity using the environmental DNA approach, we undertook metabarcoding based on the CO1 gene. Samples were collected using 0.22 mM pore-sized Sterivex filters during TAE2 undertaken in 2018, from one site at Deception Island (2 filters), one site at Nansen Island (2 filters), and three sites (one offshore) at Robert Island. A total of 20 taxa were identified (unique hits with BLAST percent identity ≥ 97%) belonging to three kingdoms (Chromista, Plantae, Animalia), nine phyla, 11 classes, 17 orders, 19 families, and 20 genera. Of these, 18 were identified to the species level, one to the genus level, and the other one to the family level. Genetically identified taxa included seven planktonic algae, nine seaweeds, a stalked jellyfish, a nematode, a planktonic copepod, and a demersal fish. In addition, 129 unique OTUs were detected (unique hits with BLAST percent identity &lt; 97%) as unidentified. These results indicate the high levels of undocumented genetic diversity (without CO1 barcode sequences in GenBank) in the Antarctic Peninsula region and adjacent waters, and the need for more work to complete the reference barcode databases for the continent. A dendrogram resulting from cluster analysis (Bray-Curtis similarity measure, group-average linkage) based on the presence/absence data of 20 identified species revealed three well-defined sample (i.e. filter containing DNA fragments of multiple taxa) groups, which almost coincided with their geographical locations. First group included samples (filters) collected from the coast of Deception Island and the second one from the coast of Robert Island, both in the South Shetland Islands, off the northern tip of the Antarctic Peninsula. The third group included samples from Nansen Island coast (off the west coast of Graham Land, Antarctic Peninsula) together with the only sample collected offshore, off Robert Island. The significance of this clustering, thus the difference among sampling sites with regard to species composition, was confirmed by Analysis of Similarity (ANOSIM) results (Global R = 0.982, p = 0.001). The highest number of identified taxa (per filter) and unidentified OTUs (per filter) were observed offshore off Robert Island. Considering that all of the other sampling sites were by the coasts of islands, this observation indicates i) the offshore waters might contain more DNA-bearing material than coastal sites, and/or ii) a methodological issue where the high phytoplankton and suspended matter concentrations by the coasts created a bottleneck in terms of capturing actual species diversity at the coasts, due to clogging of filters by phytoplankton and fine suspended particles.

Ammothea tibialis, a new pycnogonid from Drake Passage, Antarctica

2002 ◽  
Vol 14 (2) ◽  
pp. 171-173 ◽  
Author(s):  
Tomás Munilla León
Keyword(s):  
Southern Ocean ◽  
Drake Passage ◽  
Historical Background ◽  
South Shetland Islands ◽  
Falkland Islands ◽  
Scotia Sea ◽  
Shetland Islands ◽  
Bransfield Strait ◽  
Livingston Island ◽  
The Family

The most recent reports about the family Ammotheidae of pycnogonids from Southern Ocean waters are those of Munilla (2000, 2001, Scotia Sea), Pushkin (1993, various zones), Bamber (1995, Falkland Islands and South Shetland Islands) and Child (1994, various zones) who also provide historical background. Some species from Livingston Island and surrounding waters (South Shetland Islands, Drake Passage, Bransfield Strait) have been documented previously, mainly by Gordon (1932), Fry & Hedgpeth (1969), Pushkin (1993) and the papers of Child and Bamber mentioned above. Keys to this genus are given in Clark (1977) and Child (1994).

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