Sedimentology of the Permian Radok Conglomerate in the Beaver Lake area of MacRobertson Land, East Antarctica

1995 ◽  
Vol 132 (1) ◽  
pp. 51-63 ◽  
Author(s):  
C. R. Fielding ◽  
J. A. Webb
Keyword(s):  
Sediment Accumulation ◽  
East Antarctica ◽  
Upper Permian ◽  
Rift System ◽  
Flow Sheet ◽  
Lake Area ◽  
Organic Sediment ◽  
Sediment Gravity Flow ◽  
Beaver Lake ◽  
Coal Measures

AbstractThe mid- to Upper Permian Radok Conglomerate, the lowermost formation of the Permo-Triassic Amery Group, crops out in the Beaver Lake area of the northern Prince Charles Mountains, East Antarctica. Outcrop is confined to a north-south elongate, fault-bounded corridor interpretedas a remnant of a continental extensional basin formed during Late Palaeozoic times. This basinforms a small part of the much larger Lambert Graben, a major continental rift system. The RadokConglomerate consists of interbedded conglomerates, argillaceous sandstones, siltstones, and minor, thin carbonaceous siltstones and coals. Textural, petrographic, palaeocurrent and other data suggestlocal derivation from Precambrian massifs to the immediate west, during a period of fault activity.The unit is a minimum of 400 m thick, the base being unexposed, and grossly fines upward. It isabruptly overlain by quartzo-feldspathic sandstone-dominated rocks of the Upper Permian Bainmedart Coal Measures. Seven recurrent lithofacies have been recognized with the Radok Conglomerate, and are interpreted as the products of poorly-confined stream flow, sheet flow and sediment gravity flow processes, suspension fallout in shallow standing water, and organic sediment accumulation in peat-forming wetlands. The unit as a whole is interpreted as having accumulated as a coarse alluvial apron along the western margin of a ?graben extensional trough. Similar, though poorly exposed, facies are exposed on the eastern margin of the basin and may reflect similar depositional systems. Towards the top of the Radok Conglomerate, typical Radok lithologies are interbedded with quartzo-feldspathic sandstones derived from the south, precursors of the overlying Bainmedart Coal Measures. Interference between transverse (Radok) and axial (Bainmedart) drainage is possibly related to progressive infilling of extensional topography, thereby allowing axially flowing rivers to avulse increasingly into the Beaver Lake region from the main Lambert Graben.

A geological reconnaissance of the Radok Lake area, Amery Oasis, Prince Charles Mountains

1990 ◽  
Vol 2 (1) ◽  
pp. 53-66 ◽  
Author(s):  
B.C. McKelvey ◽  
N.C.N. Stephenson
Keyword(s):  
Granulite Facies ◽  
Alluvial Fan ◽  
Lake Area ◽  
Granulite Facies Metamorphism ◽  
Metamorphic Basement ◽  
Beaver Lake ◽  
Proterozoic Basement ◽  
Uplift And Erosion ◽  
Lambert Glacier ◽  
Coal Measures

At Radok Lake, northern Prince Charles Mountains, more than 2500 m of Permian Amery Group strata in the Beaver Lake graben are downfaulted against a Proterozoic metamorphic basement. An irregular blanket of late Cenozoic Pagodroma Tillite, up to 100 m thick, overlies the Permian strata and Proterozoic basement. The metamorphic basement comprises repeatedly deformed, high-grade felsic, mafic, aluminous and minor calc-silicate rocks derived from igneous and sedimentary precursors. Low- to medium-pressure granulite-facies metamorphism, assumed to be the ~1000 Ma event widely recorded in the East Antarctic Shield, was followed by incipient to moderate amphibolite-facies retrogression. Three folding events are recognized. Sporadic occurrences of pseudotachylite in the basement represent seismic faulting after substantial uplift and erosion. At the southern end of Radok Lake the Permian coarse alluvial fan facies, the Radok Conglomerate, is overlain disconformably by the Dart Fields Conglomerate, a basal member of the Bainmedart Coal Measures. Five kilometres along strike the deltaic Panorama Point beds, containing sideritic ironstone strata, are overlain conformably by arkosic sandstones of the basal Bainmedart Coal Measures. The Amery Group is intruded by two alnöite sills and at least five altered alkaline mafic dykes. The Pagodroma Tillite contains reworked marine microfossils and records the erosion of higher latitude Cenozoic marine sequences by an expanding ancestral Lambert Glacier.

Revised stratigraphy of the Permian Bainmedart Coal Measures, northern Prince Charles Mountains, East Antarctica

1997 ◽  
Vol 134 (3) ◽  
pp. 335-353 ◽  
Author(s):  
STEPHEN MCLOUGHLIN ◽  
ANDREW N. DRINNAN
Keyword(s):  
Alluvial Fan ◽  
East Antarctica ◽  
Coal Measure ◽  
Rift System ◽  
Middle Portion ◽  
Early Mesozoic ◽  
Late Palaeozoic ◽  
Sedimentary Succession ◽  
Transantarctic Mountains ◽  
Coal Measures

The Bainmedart Coal Measures constitute the middle portion of the Permian–Triassic Amery Group, which represents the only substantial Palaeozoic–Mesozoic sedimentary succession exposed in eastern Antarctica outside the Transantarctic Mountains. The coal measures disconformably or unconformably overlie alluvial fan deposits of the Radok Conglomerate and are conformably overlain by the dominantly fluviatile Flagstone Bench Formation. The coal measures were deposited within alluvial settings dominated by north to northeasterly flowing, low-sinuosity rivers chiefly confined to broad, fault-bounded, valleys of the Lambert Graben, a major late Palaeozoic to early Mesozoic failed rift system. Both climatic and local tectonic factors are considered to have been the major influences on the pattern of coal measure sedimentation. Recent mapping has identified a much greater thickness of sediments within the coal measures than had been inferred previously. The Bainmedart Coal Measures are formally subdivided into six members. In ascending stratigraphic order these are: Dart Fields Conglomerate Member (<3 m thick), Toploje Member (c. 300 m thick), Dragons Teeth Member (15–25 m thick), Glossopteris Gully Member (c. 670 m thick), Grainger Member (c. 350 m thick) and McKinnon Member (c. 530 m thick).

scholarly journals Ice flow velocities over Vostok Subglacial Lake, East Antarctica, determined by 10 years of GNSS observations

2013 ◽  
Vol 59 (214) ◽  
pp. 315-326 ◽  
Author(s):  
A. Richter ◽  
D.V. Fedorov ◽  
M. Fritsche ◽  
S.V. Popov ◽  
V.Ya. Lipenkov ◽  
...  
Keyword(s):  
Flow Velocity ◽  
East Antarctica ◽  
Global Navigation Satellite Systems ◽  
Steady Increase ◽  
Lake Area ◽  
Ice Flow ◽  
Satellite Systems ◽  
Subglacial Lake ◽  
Gnss Observations ◽  
Flow Velocities

AbstractRepeated Global Navigation Satellite Systems (GNSS) observations were carried out at 50 surface markers in the Vostok Subglacial Lake (East Antarctica) region between 2001 and 2011. The horizontal ice flow velocity vectors were derived with accuracies of 1 cm a−1 and 0.5°, representing the first reliable information on ice flow kinematics in the northern part of the lake. Within the lake area, ice flow velocities do not exceed 2 m a−1. The ice flow azimuth is southeast in the southern part of the lake and turns gradually to east-northeast in the northern part. In the northern part, as the ice flow enters the lake at the western shore, the velocity decreases towards the central lake axis, then increases slightly past the central axis. In the southern part, a continued acceleration is observed from the central lake axis across the downstream grounding line. Based on the observed flow velocity vectors and ice thickness data, mean surface accumulation rates are inferred for four surface segments between Ridge B and Vostok Subglacial Lake and show a steady increase towards the north.

scholarly journals Forty-seven new subglacial lakes in the 0–110° E sector of East Antarctica

2007 ◽  
Vol 53 (181) ◽  
pp. 289-297 ◽  
Author(s):  
Sergey V. Popov ◽  
Valery N. Masolov
Keyword(s):  
Heat Flux ◽  
Scientific Work ◽  
East Antarctica ◽  
Lake Area ◽  
Geothermal Heat ◽  
Subglacial Lake ◽  
Deep Faults ◽  
Radio Echo Sounding ◽  
Subglacial Lakes ◽  
Echo Sounding

AbstractDuring the summer field seasons of 1987–91, studies of central East Antarctica by airborne radio-echo sounding commenced. This scientific work continued in the 1990s in the Vostok Subglacial Lake area and along the traverse route from Mirny, and led to the discovery of 16 new subglacial water cavities in the areas of Domes Fuji and Argus and the Prince Charles Mountains. Twenty-nine subglacial water cavities were revealed in the area near Vostok, along with a feature we believe to be a subglacial river. Two subglacial lakes were discovered along the Mirny–Vostok traverse route. These are located 50 km north of Komsomolskaya station and under Pionerskaya station. We find high geothermal heat flux in the vicinity of the largest of the subglacial lakes, and suggest this may be due to their location over deep faults where additional mantle heat is available.

Exploring the relationship between organic deposition resulting from marshes and autogenic scales in deltaic stratigraphy

2021 ◽  
Author(s):  
Jose Silvestre ◽  
Kelly Sanks ◽  
Sam Zapp ◽  
Dutt Ripul ◽  
John Shaw ◽  
...  
Keyword(s):  
Sea Level ◽  
Sediment Accumulation ◽  
Organic Production ◽  
Transport Systems ◽  
Constant Input ◽  
Kaolinite Clay ◽  
Clastic Sediment ◽  
Organic Sediment ◽  
Stratigraphic Architecture

&lt;p&gt;Many deltas contain extensive marshes, typically defined as laterally extensive, low energy settings tied to a narrow elevation window around sea level. Biological activity in marshes results in in-situ organic sediment accumulation that has the potential to be stored in the sedimentary record. However, it is unclear how marshes interact with channels that transport the clastic sediment and typically control autogenic stratigraphic architecture. We present results from a physical experiment designed to explore the coupled evolution of marshes and deltas over geologic timescales. In the experiment, deltaic channels self-organized due to constant input rates of water and clastic sediment that experience constant long-term accommodation production through sea-level rise. A low bulk density kaolinite clay was deposited on the delta-top following rules developed by the ecology community for in-situ organic production. The kaolinite clay serves as a proxy for the in-situ organic sediments in overbank regions. As such, the autogenic processes of the clastic transport system, which influence elevation relative to sea-level, also exert a control on the scales of preserved organic-rich strata. We quantify the fraction of the organic sediment proxy in the fluvio-deltaic deposit to define a transfer function between the accumulation of organic sediment and its preservation beneath the morphodynamically active layer. We also use synthetic stratigraphy and images of the preserved strata to characterize the spatial arrangements of organic strata, and the influence of marshes on the resulting arrangement of channel bodies. Initial findings suggest that the thickest seams are located near the mean shoreline but extend significant distances from this location due to autogenic shoreline transgressions and regressions. Quantifying these trends will inform our understanding of how in-situ organic sediment accumulation influences clastic transport systems and the structure of deltaic stratigraphy.&lt;/p&gt;

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).

Stable isotope and hydrogeochemical studies of Beaver Lake and Radok Lake, MacRobertson Land, East Antarctica

2011 ◽  
Vol 47 (4) ◽  
pp. 407-414 ◽  
Author(s):  
Ulrich Wand ◽  
Wolf-Dieter Hermichen ◽  
Erika Brüggemann ◽  
Reinhard Zierath ◽  
Valerii Dmitrievich Klokov
Keyword(s):  
Stable Isotope ◽  
East Antarctica ◽  
Beaver Lake

scholarly journals An investigation into the forces that drive ice-shelf rift propagation on the Amery Ice Shelf, East Antarctica

2008 ◽  
Vol 54 (184) ◽  
pp. 17-27 ◽  
Author(s):  
Jeremy N. Bassis ◽  
Helen A. Fricker ◽  
Richard Coleman ◽  
Jean-Bernard Minster
Keyword(s):  
East Antarctica ◽  
Force Balance ◽  
Rift System ◽  
Ice Shelf ◽  
Short Term ◽  
Ancillary Data ◽  
Dominant Term ◽  
Wind Speeds ◽  
Amery Ice Shelf ◽  
Rift Propagation

AbstractFor three field seasons (2002/03, 2004/05, 2005/06) we have deployed a network of GPS receivers and seismometers around the tip of a propagating rift on the Amery Ice Shelf, East Antarctica. During these campaigns we detected seven bursts of episodic rift propagation. To determine whether these rift propagation events were triggered by short-term environmental forcings, we analyzed simultaneous ancillary data such as wind speeds, tidal amplitudes and sea-ice fraction (a proxy variable for ocean swell). We find that none of these environmental forcings, separately or together, correlated with rift propagation. This apparent insensitivity of ice-shelf rift propagation to short-term environmental forcings leads us to suggest that the rifting process is primarily driven by the internal glaciological stress. Our hypothesis is supported by order-of-magnitude calculations that the glaciological stress is the dominant term in the force balance. However, our calculations also indicate that as the ice shelf thins or the rift system matures and iceberg detachment becomes imminent, short-term stresses due to winds and ocean swell may become more important.

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