Radar-detected englacial stratigraphy in the Pensacola Mountains, Antarctica: implications for recent changes in ice flow and accumulation

Campbell, Seth; Balco, Greg; Todd, Claire; Conway, H.; Huybers, K. M.; Simmons, C. T.; Vermeulen, Michael

doi:10.3189/2013aog63a371

Cited by 15 publications

(12 citation statements)

References 28 publications

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“…Having traced the radiostratigraphy using the methods described above, we then seek to date these observed reflections. While inferences regarding ice sheet dynamics from reflection morphology alone are valuable [e.g., Conway et al ., ; Catania et al ., ; Hindmarsh et al ., ; Rippin et al ., ; Catania and Neumann , ; Campbell et al ., ; Christianson et al ., ; Sime et al ., ], the value of traced reflections can increase substantially if they are also dated [e.g., Whillans , ; Fahnestock et al ., ; Baldwin et al ., ; Dahl‐Jensen et al ., ; Buchardt , ; Medley et al ., ]. Hence, we seek to date as many traced reflections as possible, even those that do not intersect an ice core and are not continuous.…”

Section: Methodsmentioning

confidence: 99%

Radiostratigraphy and age structure of the Greenland Ice Sheet

et al. 2015

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Several decades of ice-penetrating radar surveys of the Greenland and Antarctic ice sheets have observed numerous widespread internal reflections. Analysis of this radiostratigraphy has produced valuable insights into ice sheet dynamics and motivates additional mapping of these reflections. Here we present a comprehensive deep radiostratigraphy of the Greenland Ice Sheet from airborne deep ice-penetrating radar data collected over Greenland by The University of Kansas between 1993 and 2013. To map this radiostratigraphy efficiently, we developed new techniques for predicting reflection slope from the phase recorded by coherent radars. When integrated along track, these slope fields predict the radiostratigraphy and simplify semiautomatic reflection tracing. Core-intersecting reflections were dated using synchronized depth-age relationships for six deep ice cores. Additional reflections were dated by matching reflections between transects and by extending reflection-inferred depth-age relationships using the local effective vertical strain rate. The oldest reflections, dating to the Eemian period, are found mostly in the northern part of the ice sheet. Within the onset regions of several fast-flowing outlet glaciers and ice streams, reflections typically do not conform to the bed topography. Disrupted radiostratigraphy is also observed in a region north of the Northeast Greenland Ice Stream that is not presently flowing rapidly. Dated reflections are used to generate a gridded age volume for most of the ice sheet and also to determine the depths of key climate transitions that were not observed directly. This radiostratigraphy provides a new constraint on the dynamics and history of the Greenland Ice Sheet.Key PointsPhase information predicts reflection slope and simplifies reflection tracingReflections can be dated away from ice cores using a simple ice flow modelRadiostratigraphy is often disrupted near the onset of fast ice flow

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Section: Methodsmentioning

confidence: 99%

Radiostratigraphy and age structure of the Greenland Ice Sheet

et al. 2015

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“…We used 64 incoherent stacking traces and 0.173 mns- 1 radar wave propagation velocity. This slightly higher wave velocity compensates for the high wave velocity in firn for full ice-depth profiles (Campbell and others, 2013). In the Gifford Peaks pass zone, ice thickness detected by the radar equated to ~39-128 m, differing from the pulse-compression radar because of the alternate pass route used.…”

Section: Field Tests and Data Collectionmentioning

confidence: 96%

“…8). We set the system to 64 incoherent stacking traces and 0.189mns- 1 wave velocity for the firn profiles (Campbell and others, 2013). The measurement starts at Driscoll Glacier and finds Union Glacier at ~1000m distance.…”

Section: Field Tests and Data Collectionmentioning

confidence: 99%

A low power consumption radar system for measuring ice thickness and snow/firn accumulation in Antarctica

Uribe¹,

Zamora²,

Gacitúa³

et al. 2014

Ann. Glaciol.

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ABSTRACT. In order to measure total ice thickness and surface snow accumulation in Antarctica, we have designed and built a surveying system comprising two types of radar. This system is aimed at having low power consumption, low weight/volume and low construction cost. The system has a pulsecompression radar to measure ice thickness, and a frequency-modulated continuous wave (FM-CW) radar designed to measure hundreds of meters of surface snow/firn layers with high resolution. The pulsecompression radar operates at 155 MHz, 20 MHz of bandwidth; and the FM-CW radar operates from 550 to 900 MHz. The system was tested in December 2010 at Union Glacier (79846 0 S, 83824 0 W), West Antarctica, during an oversnow campaign, where Union and other nearby glaciers (Schanz, Schneider and Balish) were covered through 82 km of track. Ice thickness of 1540 m and snow/firn thickness of 120 m were detected in the area. The collected data allowed the subglacial topography, internal ice structure, isochronous and the snow/ice boundary layer to be detected. Here we describe radar electronics, their main features and some of the results obtained during the first test campaign. Further improvements will focus on the adaptation of the system to be implemented on board airplane platforms.

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“…Winter and others, 2016) or ice flow history (i.e. Campbell and others, 2013). Other researchers have also used GPR in other ice marginal regions in Antarctica to investigate the internal stratigraphy of debris covered glaciers (i.e.…”

Section: Introductionmentioning

confidence: 99%

Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica

et al. 2019

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Mount Achernar moraine is a terrestrial sediment archive that preserves a record of ice-sheet dynamics and climate over multiple glacial cycles. Similar records exist in other blue ice moraines elsewhere on the continent, but an understanding of how these moraines form is limited. We propose a model to explain the formation of extensive, coherent blue ice moraine sequences based on the integration of ground-penetrating radar (GPR) data with ice velocity and surface exposure ages. GPR transects (100 and 25 MHz) both perpendicular and parallel to moraine ridges at Mount Achernar reveal an internal structure defined by alternating relatively clean ice and steeply dipping debris bands extending to depth, and where visible, to the underlying bedrock surface. Sediment is carried to the surface from depth along these debris bands, and sublimates out of the ice, accumulating over time (>300 ka). The internal pattern of dipping reflectors, combined with increasing surface exposure ages, suggest sequential exposure of the sediment where ice and debris accretes laterally to form the moraine. Subsurface structure varies across the moraine and can be linked to changes in basal entrainment conditions. We speculate that higher concentrations of debris may have been entrained in the ice during colder glacial periods or entrained more proximal to the moraine sequence.

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Radar-detected englacial stratigraphy in the Pensacola Mountains, Antarctica: implications for recent changes in ice flow and accumulation

Cited by 15 publications

References 28 publications

Radiostratigraphy and age structure of the Greenland Ice Sheet

Radiostratigraphy and age structure of the Greenland Ice Sheet

A low power consumption radar system for measuring ice thickness and snow/firn accumulation in Antarctica

Formation and evolution of an extensive blue ice moraine in central Transantarctic Mountains, Antarctica

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