Bransfield Basin, Antarctic Peninsula: Not a normal backarc basin

González-Casado, J.M.; Robles, Jorge Luis Giner; López-Martı́nez, Jerónimo

doi:10.1130/0091-7613(2000)028<1043:bbapna>2.3.co;2

Cited by 26 publications

(29 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, the South Shetland Trench retains the morphology of an active subduction zone [ Maldonado et al , 1994; Jabaloy et al , 2003], and earthquake activity persists to ∼65 km depth with focal mechanisms consistent with underthrusting [ Robertson Maurice et al , 2003]. Against this background, two general tectonic models have been proposed to explain post‐3.3 Ma extension in the Bransfield Basin: (1) slow subduction at the South Shetland Trench coupled with no spreading at the Antarctic‐Phoenix Plate may allow trench roll‐back, which in turn generates extension across the Bransfield Basin [ Lawver et al , 1995; Gràcia et al , 1996; Barker and Austin , 1998; Barker et al , 2003; Robertson Maurice et al , 2003], and (2) sinistral transcurrent movement between the Antarctic and Scotia Plates along the South Scotia Ridge fault may have propagated westward past the Shackleton Fracture Zone when subduction ceased, resulting in a transtensional environment for Bransfield Basin and compression in the South Shetland Islands [ González‐Casado et al , 2000].…”

Section: Discussionmentioning

confidence: 99%

Magmatism in the Bransfield Basin: Rifting of the South Shetland Arc?

et al. 2004

View full text Add to dashboard Cite

[1] Bransfield Basin is an actively extending marginal basin separating the inactive South Shetland arc from the northern Antarctic Peninsula. Rift-related volcanism is widespread throughout the central Bransfield Basin, but the wider eastern Bransfield Basin was previously unsampled. Lavas recovered from the eastern subbasin form three distinct groups: (1) Bransfield Group has moderate large-ion lithophile element (LILE) enrichment relative to normal mid-ocean ridge basalt (NMORB), (2) Gibbs Group has strong LILE enrichment and is restricted to a relic seamount interpreted as part of the South Shetland arc, and (3) fresh alkali basalt was recovered from the NE part of the basin near Spanish Rise. The subduction-related component in Bransfield and Gibbs Group lavas is a LILE-rich fluid with radiogenic Sr, Nd, and Pb isotope compositions derived predominantly from subducting sediment. These lavas can be modeled as melts from Pacific MORB source mantle contaminated by up to 5% of the subduction-related component. They further reveal that Pacific mantle, rather than South Atlantic mantle, has underlain Bransfield Basin since 3 Ma. Magma productivity decreases abruptly east of Bridgeman Rise, and lavas with the least subduction component outcrop at that end. Both the eastward decrease in subduction component and occurrence of young alkali basalts require that subduction-modified mantle generated during the lifetime of the South Shetland arc has been progressively removed from NE to SW. This is inconsistent with previous models suggesting continued slow subduction at the South Shetland Trench but instead favors models in which the South Scotia Ridge fault has propagated westward since 3 Ma generating transtension across the basin.

show abstract

Section: Discussionmentioning

confidence: 99%

Magmatism in the Bransfield Basin: Rifting of the South Shetland Arc?

et al. 2004

View full text Add to dashboard Cite

show abstract

“…Recently, Gonzalez‐Casado et al [2000] documented two neotectonic fault trends (both SW‐NE and NW‐SE) and a mixture of normal and reverse slip senses in the South Shetland Islands arc, and used these to argue that the South Shetland Trench is permanently locked. However, they did not invalidate the previous seismic evidence of Pelayo and Wiens [1989], who located approximately 34 moderate (5 < m b < 6.5) earthquakes with predominantly dip‐slip mechanisms which they attribute to continued activity of the South Shetland outer rise, South Shetland Trench, and Bransfield Basin extensional zone.…”

Section: Small Platesmentioning

confidence: 99%

An updated digital model of plate boundaries

Bird

2003

Geochem Geophys Geosyst

2,086

1,761

View full text Add to dashboard Cite

[1] A global set of present plate boundaries on the Earth is presented in digital form. Most come from sources in the literature. A few boundaries are newly interpreted from topography, volcanism, and/or seismicity, taking into account relative plate velocities from magnetic anomalies, moment tensor solutions, and/or geodesy. In addition to the 14 large plates whose motion was described by the NUVEL-1A poles (Africa, Antarctica, Arabia, Australia, Caribbean, Cocos, Eurasia, India, Juan de Fuca, Nazca, North America, Pacific, Philippine Sea, South America), model PB2002 includes 38 small plates (Okhotsk, Amur, Yangtze, Okinawa, Sunda, Burma, Molucca Sea, Banda Sea, Timor, Birds Head, Maoke, Caroline, Mariana, North Bismarck, Manus, South Bismarck, Solomon Sea, Woodlark, New Hebrides, Conway Reef, Balmoral Reef, Futuna, Niuafo'ou, Tonga, Kermadec, Rivera, Galapagos, Easter, Juan Fernandez, Panama, North Andes, Altiplano, Shetland, Scotia, Sandwich, Aegean Sea, Anatolia, Somalia), for a total of 52 plates. No attempt is made to divide the Alps-Persia-Tibet mountain belt, the Philippine Islands, the Peruvian Andes, the Sierras Pampeanas, or the California-Nevada zone of dextral transtension into plates; instead, they are designated as ''orogens'' in which this plate model is not expected to be accurate. The cumulative-number/area distribution for this model follows a power law for plates with areas between 0.002 and 1 steradian. Departure from this scaling at the small-plate end suggests that future work is very likely to define more very small plates within the orogens. The model is presented in four digital files: a set of plate boundary segments; a set of plate outlines; a set of outlines of the orogens; and a table of characteristics of each digitization step along plate boundaries, including estimated relative velocity vector and classification into one of 7 types (continental convergence zone, continental transform fault, continental rift, oceanic spreading ridge, oceanic transform fault, oceanic convergent boundary, subduction zone). Total length, mean velocity, and total rate of area production/destruction are computed for each class; the global rate of area production and destruction is 0.108 m 2 /s, which is higher than in previous models because of the incorporation of back-arc spreading.

show abstract

“…Eight BASCs with known or inferred (from water column plumes) vent sites and appreciable exploration are listed in the InterRidge Database (IRDB; https://vents-data.interridge.org) (Table ). Seven are undergoing documented spreading (Mariana, Martinez & Taylor, ; North Fiji, Auzende et al, ; East Scotia, Livermore, ; Manus, Martinez & Taylor, ; Lau Parson et al, ; Woodlark, Taylor et al, ; and Okinawa Trough, Letouzey & Kimura, ), whereas one (Bransfield Strait) is rifting but may contain incipient oceanic crust (González‐Casado et al, ; Lawver et al, ). Bransfield Strait does host hydrothermal venting so we include it for completeness.…”

Section: Geological Settingsmentioning

confidence: 99%

The Effect of Arc Proximity on Hydrothermal Activity Along Spreading Centers: New Evidence From the Mariana Back Arc (12.7°N–18.3°N)

Baker

Walker

Chadwick

et al. 2017

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Back‐arc spreading centers (BASCs) form a distinct class of ocean spreading ridges distinguished by steep along‐axis gradients in spreading rate and by additional magma supplied through subduction. These characteristics can affect the population and distribution of hydrothermal activity on BASCs compared to mid‐ocean ridges (MORs). To investigate this hypothesis, we comprehensively explored 600 km of the southern half of the Mariana BASC. We used water column mapping and seafloor imaging to identify 19 active vent sites, an increase of 13 over the current listing in the InterRidge Database (IRDB), on the bathymetric highs of 7 of the 11 segments. We identified both high and low (i.e., characterized by a weak or negligible particle plume) temperature discharge occurring on segment types spanning dominantly magmatic to dominantly tectonic. Active sites are concentrated on the two southernmost segments, where distance to the adjacent arc is shortest (<40 km), spreading rate is highest (>48 mm/yr), and tectonic extension is pervasive. Re‐examination of hydrothermal data from other BASCs supports the generalization that hydrothermal site density increases on segments <90 km from an adjacent arc. Although exploration quality varies greatly among BASCs, present data suggest that, for a given spreading rate, the mean spatial density of hydrothermal activity varies little between MORs and BASCs. The present global database, however, may be misleading. On both BASCs and MORs, the spatial density of hydrothermal sites mapped by high‐quality water‐column surveys is 2–7 times greater than predicted by the existing IRDB trend of site density versus spreading rate.

show abstract

Bransfield Basin, Antarctic Peninsula: Not a normal backarc basin

Cited by 26 publications

References 0 publications

Magmatism in the Bransfield Basin: Rifting of the South Shetland Arc?

Magmatism in the Bransfield Basin: Rifting of the South Shetland Arc?

An updated digital model of plate boundaries

The Effect of Arc Proximity on Hydrothermal Activity Along Spreading Centers: New Evidence From the Mariana Back Arc (12.7°N–18.3°N)

Contact Info

Product

Resources

About