scholarly journals Aeromagnetic anomaly patterns reveal buried faults along the eastern margin of the Wilkes Subglacial Basin (East Antarctica)

2007 ◽  
Author(s):  
E. Armadillo ◽  
F. Ferraccioli ◽  
A. Zunino ◽  
E. Bozzo
Keyword(s):  
East Antarctica ◽  
Aeromagnetic Anomaly ◽  
Eastern Margin ◽  
Buried Faults

Revised stratigraphical nomenclature for the Permo-Triassic Flagstone Bench Formation, northern Prince Charles Mountains, East Antarctica

1993 ◽  
Vol 5 (4) ◽  
pp. 409-410 ◽  
Author(s):  
J. A. Webb ◽  
C. R. Fielding
Keyword(s):  
East Antarctica ◽  
Late Permian ◽  
Eastern Margin ◽  
Coal Measures ◽  
Early Late

The East Antarctic Craton contains only one substantial outcrop of Palaeozoic–Mesozoic strata between 0° and 150°E; this lies in Mac. Robertson Land, on the eastern margin of the northern Prince Charles Mountains. These rocks are known as the Amery Group (Mond 1972, McKelvey & Stephenson 1990) and comprise dominantly fluviatile sandstones, with subordinate shales, coals and conglomerates. The lower formations of the Amery Group, the Radok Conglomerate and Bainmedart Coal Measures, contain a diverse Stage 5 palynomorph assemblage indicating a Baigendzhinian–Tatarian age (late Early–Late Permian, hereafter abbreviated as mid–Late Permian; Dibner 1978).

Magnetic and gravity views of crust and lithosphere heterogeneity in the Wilkes Subglacial Basin of East Antarctica

2020 ◽  
Author(s):  
Egidio Armadillo ◽  
Fausto Ferraccioli ◽  
Alessandro Ghirotto ◽  
Duncan Young ◽  
Donald Blankenship ◽  
...  
Keyword(s):  
Bulk Composition ◽  
East Antarctica ◽  
Gravity Models ◽  
Gravity Gradient ◽  
Geothermal Heat ◽  
Satellite Gravity ◽  
Aeromagnetic Anomaly ◽  
Cascading Effects ◽  
Continental Scale ◽  
Lithosphere Thickness

<p>The Wilkes Subglacial Basin (WSB) is a major intraplate tectonic feature in East Antarctica. It stretches for ca 1400 km from the edge of the Southern Ocean, where it is up to 600 km wide towards South Pole, where it is less than 100 km wide. Recent modelling of its subice topography (Paxman et al., 2019, JGR) lends support to a long-standing hypothesis predicting that the wide basin is linked to flexure of more rigid and mostly Precambrian cratonic lithosphere induced by the Cenozoic uplift of the adjacent Trasantarctic Mountains,. However, there is also mounting evidence from potential field and radar exploration that its narrower structurally controlled sub-basins may have formed in response to more localised Mesozoic to Cenozoic extension and transtension that preferentially steered glacial erosion (Paxman et al., 2018, GRL).  </p><p>Here we exploit recent advancements in regional aerogeophysical data compilations and continental scale satellite gravity gradient imaging with the overarching aim of helping unveil the degree of 4D heterogeneity in the crust and lithosphere beneath the WSB. New views of crustal and lithosphere thickness stem from 3D satellite gravity modelling (Pappa et al., 2019, JGR) and these can be compared with predictions from previous flexural modelling and seismological results. By stripping out the computed effects of crustal and lithosphere thickness variations we then obtain residual intra-crustal gravity anomalies. These are in turn compared with a suite of enhanced aeromagnetic anomaly images. We then calculate depth to magnetic and gravity source estimates and use these results to help constrain the first combined 2D magnetic and gravity models for two selected regions within the WSB.</p><p>One first model reveals a major lithospheric scale boundary along the eastern margin of the northern WSB. It separates the Cambro-Ordovician Ross Orogen from a newly defined composite Precambrian Wilkes Terrane that forms the unexposed crustal basement buried beneath partially exposed early Cambrian metasediments and more recent Devonian to Jurassic sediments.</p><p>Our second model investigates a sector of the WSB further south, where the proposed Precambrian basement is modelled as being both shallower and of more felsic bulk composition. Although the lack of drilling precludes direct sampling of this cryptic basement, aeromagnetic anomaly patterns suggest that it may be akin to late Paleoproterozoic to Mesoproterozoic igneous basement exposed in part of the Gawler and Curnamona cratons in South Australia. We conclude that these first order differences in basement depth, bulk composition and thickness of metasediment/sediment cover are a key and previously un-appreciated intra-crustal boundary condition, which is likely to affect geothermal heat flux variability beneath different sectors of the WSB, with potential cascading effects on subglacial hydrology and the flow of the overlying East Antarctic Ice Sheet.</p>

scholarly journals Absence of evidence for Palaeoproterozoic eclogite-facies metamorphism in East Antarctica: no record of subduction orogenesis during Nuna development

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dillon A. Brown ◽  
Laura J. Morrissey ◽  
John W. Goodge ◽  
Martin Hand
Keyword(s):  
Plate Boundary ◽  
South Australia ◽  
East Antarctica ◽  
Geological Evidence ◽  
Crustal Shortening ◽  
Eastern Margin ◽  
Facies Metamorphism ◽  
Eclogite Facies ◽  
Early Palaeozoic ◽  
Collisional Orogenesis

AbstractThe cratonic elements of proto-Australia, East Antarctica, and Laurentia constitute the nucleus of the Palaeo-Mesoproterozoic supercontinent Nuna, with the eastern margin of the Mawson Continent (South Australia and East Antarctica) positioned adjacent to the western margin of Laurentia. Such reconstructions of Nuna fundamentally rely on palaeomagnetic and geological evidence. In the geological record, eclogite-facies rocks are irrefutable indicators of subduction and collisional orogenesis, yet occurrences of eclogites in the ancient Earth (> 1.5 Ga) are rare. Models for Palaeoproterozoic amalgamation between Australia, East Antarctica, and Laurentia are based in part on an interpretation that eclogite-facies metamorphism and, therefore, collisional orogenesis, occurred in the Nimrod Complex of the central Transantarctic Mountains at c. 1.7 Ga. However, new zircon petrochronological data from relict eclogite preserved in the Nimrod Complex indicate that high-pressure metamorphism did not occur in the Palaeoproterozoic, but instead occurred during early Palaeozoic Ross orogenesis along the active convergent margin of East Gondwana. Relict c. 1.7 Ga zircons from the eclogites have trace-element characteristics reflecting the original igneous precursor, thereby casting doubt on evidence for a Palaeoproterozoic convergent plate boundary along the current eastern margin of the Mawson Continent. Therefore, rather than a Palaeoproterozoic (c. 1.7 Ga) history involving subduction-related continental collision, a pattern of crustal shortening, magmatism, and high thermal gradient metamorphism connected cratons in Australia, East Antarctica, and western Laurentia at that time, leading eventually to amalgamation of Nuna at c. 1.6 Ga.

Crustal architecture of the largest pull-apart basin in East Antarctica unveiled

2020 ◽  
Author(s):  
Laura Crispini ◽  
Fausto Ferraccioli ◽  
Egidio Armadillo ◽  
Andreas Läufer ◽  
Antonia Ruppel
Keyword(s):  
Tectonic Setting ◽  
Field Work ◽  
Strike Slip ◽  
East Antarctica ◽  
Large Igneous Province ◽  
Rift System ◽  
Study Region ◽  
Eastern Margin ◽  
Pull Apart Basin ◽  
Slip Deformation

<p>The West Antarctic Rift System (WARS) is known to have experienced distributed/wide mode extension in the Cretaceous, followed by narrow mode and variably oblique extension/transtension in the Cenozoic, the latter potentially linked to the onset of oceanic seafloor spreading within the Adare Basin (Davey et al., 2016, GRL). However, onshore the extent and impact of Cenozoic extension and transtension within the Transantarctic Mountains sector of East Antarctica is currently much less well-constrained from a geophysical perspective.</p><p>Here we combine aeromagnetic, aerogravity, land-gravity and bedrock topography imaging to help constrain the extent, architecture and kinematics of the largest Cenozoic pull-apart basin recognised so far in East Antarctica, the Rennick Graben (RG).</p><p>Enhanced potential field imaging reveals the extent of a Jurassic tholeiitic Large Igneous Province preserved within the RG and the inherited structural architecture of its basement, including remnants of uplifted ca 530-500 Ma arc basement in the northern Wilson Terrane and a ca 490-460 Ma subglacial thrust fault belt separating the Cenozoic western flank of the RG from the eastern margin of Wilkes Subglacial Basin (WSB).</p><p>The architecture of the RG is best explained in terms of a major composite right-lateral pull-part basin that extends from the Oates Coast to the Southern Cross Mountains block. We propose that Cenozoic strike-slip deformation kinematically connected the RG with both the western edge of the WARS and the eastern margin of the WSB. An earlier phase of left-lateral strike slip deformation is also emerging from recent geological field work in the study region but only relatively subtle offsets in aeromagnetic anomaly patterns are visible in currently available regional datasets.</p><p>We conclude that the RG is part of a wider distributed region of the continental lithosphere in East Antarctica that was deformed in response to an evolving Cenozoic transtensional tectonic setting that may have also affected enigmatic sub-basins such as the Cook Basins in the adjacent WSB region.</p>

Some centric diatoms (Bacillariophyta) from Neogene deposits of the Fisher Massif (Prince Charles Mountains, East Antarctica)

2011 ◽  
Vol 45 ◽  
pp. 32-49
Author(s):  
R. M. Gogorev ◽  
Z. V. Pushina
Keyword(s):  
Marine Sediments ◽  
East Antarctica ◽  
Benthic Diatoms ◽  
Detailed Data ◽  
Planktonic Algae ◽  
Centric Diatoms ◽  
Planktonic Diatom ◽  
Oceanic Species ◽  
Diatom Complexes

The richest diatom complexes have revealed due to the study of glacial-marine sediments sampled in the Fisher Massif (Prince Charles Mountains, East Antarctica) during 52nd and 53rd Russian Antarctic Expeditions (Polar Marine Geol. Survey Expedition) in 2006/07 and 2007/08. Three diatom complexes are distinguished according to different palaeoecological conditions: the planktonic one is located in the basis of the outcrop, while mixed planktonic-benthic and benthic ones being located above. The planktonic diatom complexes are dominated by two oceanic species Actinocyclus ingens (up to 8%) and Denticulopsis simonseni (up to 80%). There are 15 planktonic algae, e. g. Eucampia аntarctica, Fragilariopsis spp., Rhizosolenia spp., Rouxia antarctica, Podosira antarctica sp. nov., Stellarima microtrias; and also unknown and non-described benthic diatoms Achnanthes sp., Cocconeis spp., Rhabdonema (s. l.) spp. and Synedra (s. l.) spp. Detailed data on morphology and taxonomy of 10 centric diatoms are presented, including 3 newly described species.

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