The Gondwanan margin in West Antarctica: insights from Late Triassic magmatism of the Antarctic Peninsula

Abstract GRACE and ICESat Antarctic mass-balance differences are resolved utilizing their dependencies on corrections for changes in mass and volume of the same underlying mantle material forced by ice-loading changes. Modeled gravimetry corrections are 5.22 times altimetry corrections over East Antarctica (EA) and 4.51 times over West Antarctica (WA), with inferred mantle densities 4.75 and 4.11 g cm−3. Derived sensitivities (Sg, Sa) to bedrock motion enable calculation of motion (δB0) needed to equalize GRACE and ICESat mass changes during 2003–08. For EA, δB0 is −2.2 mm a−1 subsidence with mass matching at 150 Gt a−1, inland WA is −3.5 mm a−1 at 66 Gt a−1, and coastal WA is only −0.35 mm a−1 at −95 Gt a−1. WA subsidence is attributed to low mantle viscosity with faster responses to post-LGM deglaciation and to ice growth during Holocene grounding-line readvance. EA subsidence is attributed to Holocene dynamic thickening. With Antarctic Peninsula loss of −26 Gt a−1, the Antarctic total gain is 95 ± 25 Gt a−1 during 2003–08, compared to 144 ± 61 Gt a−1 from ERS1/2 during 1992–2001. Beginning in 2009, large increases in coastal WA dynamic losses overcame long-term EA and inland WA gains bringing Antarctica close to balance at −12 ± 64 Gt a−1 by 2012–16.

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Data on the arc magmatism developed in the Antarctic Peninsula and Patagonia during the Late Triassic – Jurassic: a compilation of new and previous geochronology, geochemistry and isotopic tracing results.

Data in Brief ◽

10.1016/j.dib.2021.107042 ◽

2021 ◽

pp. 107042

Author(s):

Joaquin Bastias ◽

Richard Spikings ◽

Teal Riley ◽

Alexey Ulianov ◽

Anne Grunow ◽

...

Keyword(s):

Antarctic Peninsula ◽

Late Triassic ◽

Arc Magmatism ◽

Isotopic Tracing ◽

The Antarctic

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An Assessment of ERA5 Reanalysis for Antarctic Near-Surface Air Temperature

Atmosphere ◽

10.3390/atmos12020217 ◽

2021 ◽

Vol 12 (2) ◽

pp. 217

Author(s):

Jiangping Zhu ◽

Aihong Xie ◽

Xiang Qin ◽

Yetang Wang ◽

Bing Xu ◽

...

Keyword(s):

Linear Relationship ◽

Antarctic Peninsula ◽

Austral Summer ◽

Correlation Coefficients ◽

East Antarctica ◽

West Antarctica ◽

Austral Spring ◽

Reanalysis Dataset ◽

Near Surface ◽

The Antarctic

The European Center for Medium-Range Weather Forecasts (ECMWF) released its latest reanalysis dataset named ERA5 in 2017. To assess the performance of ERA5 in Antarctica, we compare the near-surface temperature data from ERA5 and ERA-Interim with the measured data from 41 weather stations. ERA5 has a strong linear relationship with monthly observations, and the statistical significant correlation coefficients (p < 0.05) are higher than 0.95 at all stations selected. The performance of ERA5 shows regional differences, and the correlations are high in West Antarctica and low in East Antarctica. Compared with ERA5, ERA-Interim has a slightly higher linear relationship with observations in the Antarctic Peninsula. ERA5 agrees well with the temperature observations in austral spring, with significant correlation coefficients higher than 0.90 and bias lower than 0.70 °C. The temperature trend from ERA5 is consistent with that from observations, in which a cooling trend dominates East Antarctica and West Antarctica, while a warming trend exists in the Antarctic Peninsula except during austral summer. Generally, ERA5 can effectively represent the temperature changes in Antarctica and its three subregions. Although ERA5 has bias, ERA5 can play an important role as a powerful tool to explore the climate change in Antarctica with sparse in situ observations.

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Sub-decadal variations in outlet glacier terminus positions in Victoria Land, Oates Land and George V Land, East Antarctica (1972–2013)

Antarctic Science ◽

10.1017/s0954102017000074 ◽

2017 ◽

Vol 29 (5) ◽

pp. 468-483 ◽

Cited By ~ 8

Author(s):

A.M. Lovell ◽

C.R. Stokes ◽

S.S.R. Jamieson

Keyword(s):

Antarctic Peninsula ◽

East Antarctica ◽

West Antarctica ◽

Position Change ◽

Outlet Glacier ◽

Glacier Terminus ◽

Victoria Land ◽

Decadal Scale ◽

Decadal Variations ◽

The Antarctic

AbstractRecent work has highlighted the sensitivity of marine-terminating glaciers to decadal-scale changes in the ocean–climate system in parts of East Antarctica. However, compared to Greenland, West Antarctica and the Antarctic Peninsula, little is known about recent glacier change and potential cause(s), with several regions yet to be studied in detail. In this paper, we map the terminus positions of 135 glaciers along the coastline of Victoria Land, Oates Land and George V Land from 1972–2013 at a higher temporal resolution (sub-decadal intervals) than in previous research. These three regions span a range of climatic and oceanic conditions and contain a variety of glacier types. Overall, from 1972–2013, 36% of glaciers advanced, 25% retreated and the remainder showed no discernible change. On sub-decadal timescales, there were no clear trends in glacier terminus position change. However, marine-terminating glaciers experienced larger terminus position changes compared with terrestrial glaciers, and those with an unconstrained floating tongue exhibited the largest variations. We conclude that, unlike in Greenland, West Antarctica and the Antarctic Peninsula, there is no clear glacier retreat in the study area and that most of the variations are more closely linked to glacier size and terminus type.

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A revised geochronology of Thurston Island, West Antarctica, and correlations along the proto-Pacific margin of Gondwana

Antarctic Science ◽

10.1017/s0954102016000341 ◽

2016 ◽

Vol 29 (1) ◽

pp. 47-60 ◽

Cited By ~ 18

Author(s):

T.R. Riley ◽

M.J. Flowerdew ◽

R.J. Pankhurst ◽

P.T. Leat ◽

I.L. Millar ◽

...

Keyword(s):

Antarctic Peninsula ◽

West Antarctica ◽

Granitoid Magmatism ◽

Andean Cordillera ◽

Crustal Block ◽

Form Part ◽

Gondwana Margin ◽

Pacific Margin ◽

Mesozoic Magmatism ◽

The Antarctic

AbstractThe continental margin of Gondwana preserves a record of long-lived magmatism from the Andean Cordillera to Australia. The crustal blocks of West Antarctica form part of this margin, with Palaeozoic–Mesozoic magmatism particularly well preserved in the Antarctic Peninsula and Marie Byrd Land. Magmatic events on the intervening Thurston Island crustal block are poorly defined, which has hindered accurate correlations along the margin. Six samples are dated here using U-Pb geochronology and cover the geological history on Thurston Island. The basement gneisses from Morgan Inlet have a protolith age of 349±2 Ma and correlate closely with the Devonian–Carboniferous magmatism of Marie Byrd Land and New Zealand. Triassic (240–220 Ma) magmatism is identified at two sites on Thurston Island, with Hf isotopes indicating magma extraction from Mesoproterozoic-age lower crust. Several sites on Thurston Island preserve rhyolitic tuffs that have been dated at 182 Ma and are likely to correlate with the successions in the Antarctic Peninsula, particularly given the pre-break-up position of the Thurston Island crustal block. Silicic volcanism was widespread in Patagonia and the Antarctic Peninsula at ~ 183 Ma forming the extensive Chon Aike Province. The most extensive episode of magmatism along the active margin took place during the mid-Cretaceous. This Cordillera ‘flare-up’ event of the Gondwana margin is also developed on Thurston Island with granitoid magmatism dated in the interval 110–100 Ma.

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Major increases projected in extreme surface melt events in Antarctica, even under a moderate emission scenario

10.5194/egusphere-egu2020-21267 ◽

2020 ◽

Author(s):

Sarah Feron ◽

Raul Cordero

Keyword(s):

Sea Level ◽

Antarctic Peninsula ◽

Climate Models ◽

Emission Scenario ◽

Global Climate ◽

Global Climate Models ◽

Reference Period ◽

West Antarctica ◽

Surface Melt ◽

The Antarctic

<p>Surface Melt (SM) is one of the factors that contribute to sea level rise; surface&#160;meltwater draining through the ice and beneath&#160;Antarctic&#160;glaciers may cause acceleration in their flow towards the sea. Changes in the frequency of relatively warm days (including heatwaves) can substantially alter the SM variability, thus leading to extreme melting events.&#160;By using simulations from 13 Global Climate Models (GCMs) and according to a moderate representative concentration pathways (RCP4.5), here we show that the frequency of extreme SM events (SM90; according to the 90th percentile over the reference period 1961-1990) may significantly increase in coastal areas of West Antarctica; in particular in the Antarctic Peninsula. By the end of the century SM90 estimates are expected to increase from currently 0.10 kg/m2/day to about 0.45 kg/m2/day in the Antarctic Peninsula. Increments in SM90 estimates are not just driven by changes in the average SM, but also by the variability in SM. The latter is expected to increase by around 50% in the Antarctic Peninsula.</p>

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Population structure of Friesea grisea (Collembola, Neanuridae) in the Antarctic Peninsula and Victoria Land: evidence for local genetic differentiation of pre-Pleistocene origin

Antarctic Science ◽

10.1017/s0954102010000775 ◽

2010 ◽

Vol 22 (6) ◽

pp. 757-765 ◽

Cited By ~ 18

Author(s):

Giulia Torricelli ◽

Francesco Frati ◽

Peter Convey ◽

Marco Telford ◽

Antonio Carapelli

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Genetic Structure ◽

Antarctic Peninsula ◽

West Antarctica ◽

Genetic Structure Of Populations ◽

Victoria Land ◽

Springtail Species ◽

Ancestral Haplotypes ◽

The Antarctic

AbstractFriesea grisea is the only springtail species currently described from both East (Victoria Land) and West Antarctica (Antarctic Peninsula), although levels of genetic divergence between the two regions suggest the possibility of cryptic species. Determining the genetic structure of populations in the two regions is necessary in order to compare the effects of the different environmental conditions in the two regions, the different evolutionary histories of their inhabitants, and for assessing any influence of latitude in each region on genetic diversity. We analysed sequences of the mitochondrial COX1 and ATP6 genes from a total of 111 individuals for 17 sites (nine on the Antarctic Peninsula and eight in Victoria Land), to assess levels of genetic diversity. Both regions have their own unique sets of haplotypes, differing by about 20% of their nucleotide sequences. A similar number of haplotypes was found in the two regions, and within each we found two groups of populations sharing no haplotypes. In the Antarctic Peninsula, two, presumably ancestral, haplotypes are dominant in frequency. In Victoria Land, the Cape Hallett population showed a distinct set of haplotypes, genetically different from the southernmost populations, suggesting differentiation on pre-Pleistocene timescales.

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Glacier Fluctuations in George VI Sound Area, West Antarctica (Abstract only)

Annals of Glaciology ◽

10.1017/s0260305500003165 ◽

1982 ◽

Vol 3 ◽

pp. 345 ◽

Cited By ~ 1

Author(s):

C.M. Clapperton ◽

D.E. Sugden

Keyword(s):

Antarctic Peninsula ◽

Ice Age ◽

List Type ◽

West Antarctica ◽

Ice Shelf ◽

Scotia Sea ◽

Field Evidence ◽

Glacial Chronology ◽

History Of ◽

The Antarctic

George VI Sound lies between Alexander Island and the Antarctic Peninsula and is over 20 km wide and 500 km long. At present an ice shelf fills the sound and is nourished largely by ice from the Antarctic Peninsula which flows across the sound to ground against the coast of Alexander Island. Ice-free areas, comprising small nunataks and larger massifs, fringe both sides of the sound and contain evidence of the former glacial history of the area. This paper describes the field evidence in detail and uses geomorphological and sedimentary analyses to put forward a relative glacial chronology, constrained by two absolute dates. The chronology distinguishes: (1) a maximum state during which all ice-free areas were submerged by ice flowing into George VI Sound from both the Antarctic Peninsula and Alexander Island and thence along the sound as an ice stream. This occurred in the late Wisconsin and followed an interstadial or interglacial when George VI Sound was free of an ice shelf. (2) a valley-based stadial during overall deglaciation represented by pronounced marginal moraines on Alexander Island. (3) deglaciation to a stage where there was less landbased ice on Alexander Island than today. At this stage isostatic recovery was incomplete, relative sealevel was higher, and George VI Ice Shelf penetrated further into embayments on Alexander Island than at present. (4) probable disappearance of George VI Ice Shelf by 6.5 14C ka BP. (5) neoglacial readvance of local glaciers on Alexander Island to form three closely spaced terminal moraines and the growth of a new George VI Ice Shelf which was again more extensive than at present. (6) subsequent oscillations of both smaller Alexander Island glaciers and George VI Ice Shelf probably during the Little Ice Age. These fluctuations are similar to those in other sub-Antarctic Islands in the Scotia Sea and also in southern Chile.

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Chapter 2.2a Palmer Land and Graham Land volcanic groups (Antarctic Peninsula): volcanology

Geological Society London Memoirs ◽

10.1144/m55-2018-36 ◽

2021 ◽

pp. M55-2018-36 ◽

Cited By ~ 3

Author(s):

Teal R. Riley ◽

Philip T. Leat

Keyword(s):

Antarctic Peninsula ◽

Volcanic Rocks ◽

Flood Basalt ◽

Large Igneous Province ◽

West Antarctica ◽

Silicic Volcanic ◽

Pacific Margin ◽

Southward Extension ◽

Continental Magmatism ◽

The Antarctic

AbstractThe break-up of Gondwana during the Early–Middle Jurassic was associated with flood basalt volcanism in southern Africa and Antarctica (Karoo–Ferrar provinces), and formed one of the most extensive episodes of continental magmatism of the Phanerozoic. Contemporaneous felsic magmatism along the proto-Pacific margin of Gondwana has been referred to as a silicic large igneous province, and is exposed extensively in Patagonian South America, the Antarctic Peninsula and elsewhere in West Antarctica. Jurassic-age silicic volcanism in Patagonia is defined as the Chon Aike province and forms one of the most voluminous silicic provinces globally. The Chon Aike province is predominantly pyroclastic in origin, and is characterized by crystal tuffs and ignimbrite units of rhyolite composition. Silicic volcanic rocks of the once contiguous Antarctic Peninsula form a southward extension of the Chon Aike province and are also dominated by silicic ignimbrite units, with a total thickness exceeding 1 km. The ignimbrites include high-grade rheomorphic ignimbrites, as well as unwelded, lithic-rich ignimbrites. Rhyolite lava flows, air-fall horizons, debris-flow deposits and epiclastic deposits are volumetrically minor, occurring as interbedded units within the ignimbrite succession.

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