Sediment flux through the McMurdo Ice Shelf in Windless Bight, Antarctica

Dunbar, Gavin B.; Bertler, Nancy A. N.; McKay, Robert

doi:10.1016/j.gloplacha.2009.05.007

Cited by 34 publications

(48 citation statements)

References 16 publications

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“…9). The southernmost point up to which we were able to track the dust horizon lies relatively close to the location of a 20 m firn core analysed in Dunbar et al (2009). They estimate an accumulation rate of 53 ± 20 cm of snow per year.…”

Section: Discussionmentioning

confidence: 57%

“…A previously identified dust layer (Dunbar et al, 2009) originating from a severe storm (with maximum southerly wind speeds exceeding 55 m s −1 ) that occurred on 16 May 2004 (Xiao et al, 2008) served as a reference point for dating. In 2008, we found the dust layer at a depth of 2.93 m in a snow pit near stake C3 (not shown) at L2.…”

Section: Accumulation Estimates From Stake Farms Snow Pits and Firnmentioning

confidence: 99%

“…The yellow arrow corresponds to the dust layer depth and coincides with a horizon which is more undulating than other horizons in its vicinity. The particularly strong roughness might be related to buried sastrugis caused by the storm event in May 2004 (Steinhoff et al, 2008;Dunbar et al, 2009). Figure 6a and b show processed radargrams from line E4 to E6 at L2, recorded in 2008 and 2009, respectively.…”

Section: Accumulation Estimates From Gpr Measurementsmentioning

confidence: 99%

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Snow accumulation and compaction derived from GPR data near Ross Island, Antarctica

et al. 2011

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Abstract. We present an improved method for estimating accumulation and compaction rates of dry snow in Antarctica with ground penetrating radar (GPR). Using an estimate of the emitted waveform from direct measurements, we apply deterministic deconvolution via the Fourier domain to GPR data with a nominal frequency of 500 MHz. This reveals unambiguous reflection horizons which can be observed in repeat measurements made one year apart. At two measurement sites near Scott Base, Antarctica, we extrapolate point measurements of average accumulation from snow pits and firn cores to a larger area by identifying a dateable dust layer horizon in the radargrams. Over an 800 m × 800 m area on the McMurdo Ice Shelf (77 • 45 S, 167 • 17 E) the average accumulation is found to be 269 ± 9 kg m −2 a −1 . The accumulation over an area of 400 m× 400 m on Ross Island (77 • 40 S, 167 • 11 E, 350 m a.s.l.) is found to be higher (404 ± 22 kg m −2 a −1 ) and shows increased variability related to undulating terrain. Compaction of snow between 2 m and 13 m depth is estimated at both sites by tracking several internal reflection horizons along the radar profiles and calculating the average change in separation of horizon pairs from one year to the next. The derived compaction rates range from 7 cm m −1 at a depth of 2 m, down to no measurable compaction at 13 m depth, and are similar to published values from point measurements.

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Section: Discussionmentioning

confidence: 57%

Section: Accumulation Estimates From Stake Farms Snow Pits and Firnmentioning

confidence: 99%

Section: Accumulation Estimates From Gpr Measurementsmentioning

confidence: 99%

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Snow accumulation and compaction derived from GPR data near Ross Island, Antarctica

et al. 2011

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“…On the basis of these considerations, data presented here, suggest that the seafloor was influenced by aeolian particles that have settled through the water column, at the time of diatomite deposition. Consistently, sediment blown onto the sea ice and released to the water column during the melting has long been suggested as the dominant source of modern lithogenic sediment in McMurdo Sound (Bentley, 1979;Barrett et al, 1983;Macpherson, 1987;Atkins and Dunbar, 2009;Dunbar et al, 2009). Moreover, increases of Ti/Al ratios within two intervals at 400-425 and 440-460 mbsf (Fig.…”

Section: Element Geochemistrymentioning

confidence: 82%

Chemostratigraphy of the early Pliocene diatomite interval from MIS AND-1B core (Antarctica): Palaeoenvironment implications

Scopelliti

Bellanca

Monien

et al. 2013

Global and Planetary Change

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The AND-1B drill core (1285 m-long) was recovered, inside the ANDRILL (ANtarctic geological DRILLing) Program, during the austral summer of 2006/07 from beneath the floating McMurdo Ice Shelf. Drilling recovered a stratigraphic succession of alternating diamictites, diatomites and volcaniclastic sediments spanning about the last 14 Ma. A core portion between 350 and 480 mbsf, including a 80 m-thick diatomite interval recording the early Pliocene warming event, was investigated in term of opal biogenic content and element geochemistry. Across the diatomite interval, in spite of the lithological uniformity, a fluctuating biogenic opal profile mirrors the δ 18O record, testifying a decrease in productivity when temperature drops as a consequence of small glacial fluctuations. The comparison of biogenic opal data with Chaetoceros spp. abundances from Konfirst et al. (2012) documents alternations between periods of high primary productivity in stratified surface waters and of enhanced terrigenous input in ice-free conditions. Cluster analysis discriminates elements associated to terrigenous input from those subject to biogenic control. Further separation in sub-cluster was interpreted in term of different element response to changes in provenance but also to depositional/early diagenetic conditions at the seafloor. Whilst K and Ti are related to different sediment sources confirming previous studies from the same interval, V, Zn and, to a lesser extent, Fe, document reducing/anoxic conditions during the diatomites deposition (in particular in 400-460 mbsf interval). Mg, Sr and Mn contents are related to authigenic carbonate precipitation whilst Ba is interested by nonsteady-state processes leading to local peaks of barium below the sulphate-rich/sulphate-poor pore water boundary where generally the low degree of barite saturation is responsible for Ba remobilization. Such alteration in depositional dynamics, responsible of the precipitation of an oxygen-depleted barium phase, was probably induced by change in sedimentation rate and/or in palaeoenvironmental conditions.

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“…Naish et al, 2007). Dunbar et al (2009-this issue) analysed a 19.8-m-long firn core from the MIS for dust concentration in order to quantify the annual flux of sediment onto the MIS at Windless Bight, examine its temporal variability and calculate its contribution to subice shelf sedimentation. By using a simple ice flow model to calculate basal melt rates, and hence dust flux through the ice shelf, they highlight the importance of the proximity of the calving (or grounding) lines for the supply of fine-grained sediment to the subice shelf cavity.…”

Section: Organisation and Volume Contentmentioning

confidence: 99%