Meltwater discharge during the Holocene from the Wilkes subglacial basin revealed by beryllium isotope analysis of marine sediments

Behrens, Bethany; Miyairi, Yosuke; Sproson, Adam D.; Yamane, Masako; Yokoyama, Yūsuke

doi:10.1002/jqs.3148

Cited by 12 publications

(15 citation statements)

References 30 publications

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“…For some new samples, existing age models confirmed a modern or (late?) Holocene age (e.g., Hartman et al, 2018;Wilson et al, 2018;Armand et al, 2018;Behrens et al, 2019). For many samples, however, no absolute age determination was available, but the use of box coring technique (Table 1) for retrieving the sediment-water interface and the dinocyst assemblages and palynofacies found (e.g., presence of more labile organic matter, such as amorphous organic matter and chitin remains) suggest a tentative modern-to-late Holocene age.…”

Section: New Surface Sediment Samples From Around Antarcticamentioning

confidence: 99%

An expanded database of Southern Hemisphere surface sediment dinoflagellate cyst assemblages and their oceanographic affinities

Thöle¹,

Nooteboom²,

Hou³

et al. 2023

Preprint

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Dinoflagellate cyst assemblages present a valuable proxy to infer paleoceanographic conditions, yet factors influencing geographic distributions of species remain largely unknown, especially in the Southern Ocean. Strong lateral transport, sea-ice dynamics and a low and uneven geographic coverage of surface sediment samples have limited the use of dinocyst assemblages as a quantitative proxy for paleo-environmental conditions such as sea-surface temperature (SST), nutrient concentrations, salinity and sea ice (presence). In this study we present a new set of surface sediment samples (n=66) from around Antarctica, doubling the number of Antarctic-proximal samples to 100 (dataset wsi_100) and increasing the total number of Southern Hemisphere samples to 655 (dataset sh_655). Additionally, we use modelled ocean conditions and apply Lagrangian techniques on all SouthernHemisphere sample stations to quantify and evaluate the influence of lateral transport on the sinking trajectory of microplankton and through that, to the inferred ocean conditions. K-means cluster analysis on the wsi_100 dataset demonstrates the strong affinity of Selenopemphix antarctica to sea-ice cover conditions, and Islandinium spp. to low-salinity conditions. For the entire Southern Hemisphere, the k-means cluster analysis identifies nine clusters with a characteristic assemblage. In most clusters a single dinocyst species dominates the assemblage. These clusters correspond to well-defined oceanic conditions in specific Southern Ocean zones or along the ocean fronts. We find that when lateral transport is predominantly zonal, the environmental parameters inferred from the sea floor assemblages mostly correspond to those of overlying ocean surface. In this case, the transport factor can thus be neglected and will not represent a bias in the reconstructions. Yet, for some individual sites, e.g., deep water sites or sites under strong current regimes, lateral transport can play a large role. The results of our study further constrain environmental conditions represented by dinocyst assemblages and the location of Southern Ocean frontal systems.

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Section: New Surface Sediment Samples From Around Antarcticamentioning

confidence: 99%

An expanded database of Southern Hemisphere surface sediment dinoflagellate cyst assemblages and their oceanographic affinities

Thöle¹,

Nooteboom²,

Hou³

et al. 2023

Preprint

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“…To directly compare with reported Be and major element (Na, Ca, Mg, Fe, Mn, Al and Ti) estimates, 29,30 10 to 30 mg of each reference material underwent whole‐rock dissolution using a treatment of 5 mL HNO 3 at 100°C, 5 mL HNO 3 :2 mL HClO 4 at 180°C followed by 3 mL HF:1 mL HNO 3 at 100°C for 4 to 5 days, and then finally 2 mL of HCl 16,33 . To represent a range of leaching methods presented in the literature, we applied a “strong” ( 9 Be strong ) and “weak” ( 9 Be weak ) leaching solution on 1 g and 0.1 g aliquots of each reference material (Table 2).…”

Section: Methodsmentioning

confidence: 99%

“…All Be abundances are presented relative to their initial sample mass material underwent whole-rock dissolution using a treatment of 5 mL HNO 3 at 100 C, 5 mL HNO 3 :2 mL HClO 4 at 180 C followed by 3 mL HF:1 mL HNO 3 at 100 C for 4 to 5 days, and then finally 2 mL of HCl. 16,33 To represent a range of leaching methods presented in the literature, we applied a "strong" ( 9 Be strong ) and "weak" ( 9 Be weak ) leaching solution on 1 g and 0.1 g aliquots of each reference material (Table 2). The strong leaching treatment involved adding 20 mL g −1 sediment of 0.04 M NH 2 OH.HCl in 25% acetic acid at 80 C for 6 h.…”

Section: Sample Treatment Proceduresmentioning

confidence: 99%

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Initial measurement of beryllium‐9 using high‐resolution inductively coupled plasma mass spectrometry allows for more precise applications of the beryllium isotope system within the Earth Sciences

Sproson

Aze

Behrens

et al. 2021

Rapid Comm Mass Spectrometry

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Rationale Precise and accurate determination of the ratio of the cosmogenic nuclide 10Be to the stable isotope 9Be (10Be/9Be) is needed across multiple fields of research within the Earth Sciences. Current techniques used to measure the 9Be content of geological materials generally require a large amount of sample or solution aliquot and present a large range of analytical precisions. Methods A range of geological reference materials underwent whole‐rock dissolution and “strong” (0.04 M NH2OH.HCl in 25% acetic acid) and “weak” (0.02 M NH2OH.HCl in 10% acetic acid) leaching to represent a range of potential applications within the geosciences. After treatment, the 9Be and major element (Na, Ca, Mg, Fe, Mn, Al and Ti) content of sample solutions were determined by high‐resolution inductively coupled plasma mass spectrometry (HR‐ICP‐MS) using a Thermo® ELEMENT XR instrument. Results The 9Be concentration of whole‐rock and leaching solutions displayed a wide range of values within each geological reference material, generally following a uniform relationship implying a potential kinetic control on NH2OH leaching, as suggested by major element profiles. A precision of 0.1 to 1.4% is achieved independent of sample size or leaching strength. Conclusions Initial results suggest that the use of HR‐ICP‐MS improves the precision of 9Be analysis for a range of geological reference materials. A high precision is maintained despite reducing the sample size or strength of leaching solution. This has implications for the use of the Be isotope system within the Earth Sciences by reducing the propagated uncertainty of 10Be/9Be ratios or the mass of sample or 9Be aliquot used.

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“…Neodymium isotope ratios are expressed as ε Nd values, the deviation of 143 Nd/ 144 Nd ratios from the Chondritic Uniform Reservoir value in parts per 10,000, and provide evidence on the locus of subglacial erosion 17 (see Methods). Authigenic Be isotope ratios are reported as 10 Be/ 9 Be ratios and are considered to be an indicator of meltwater inputs [23][24][25] (see Methods). In addition, to evaluate the extent of ice-sheet margin retreat in the WSB, we estimated changes in elevation at Talos Dome during the LIG based on the reported oxygen isotope (δ 18 O) records in Antarctic ice cores 22 .…”

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confidence: 99%

Multiple episodes of ice loss from the Wilkes Subglacial Basin during the Last Interglacial

et al. 2023

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The Last Interglacial (LIG: 130,000–115,000 years ago) was a period of warmer global mean temperatures and higher and more variable sea levels than the Holocene (11,700–0 years ago). Therefore, a better understanding of Antarctic ice-sheet dynamics during this interval would provide valuable insights for projecting sea-level change in future warming scenarios. Here we present a high-resolution record constraining ice-sheet changes in the Wilkes Subglacial Basin (WSB) of East Antarctica during the LIG, based on analysis of sediment provenance and an ice melt proxy in a marine sediment core retrieved from the Wilkes Land margin. Our sedimentary records, together with existing ice-core records, reveal dynamic fluctuations of the ice sheet in the WSB, with thinning, melting, and potentially retreat leading to ice loss during both early and late stages of the LIG. We suggest that such changes along the East Antarctic Ice Sheet margin may have contributed to fluctuating global sea levels during the LIG.

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Meltwater discharge during the Holocene from the Wilkes subglacial basin revealed by beryllium isotope analysis of marine sediments

Cited by 12 publications

References 30 publications

An expanded database of Southern Hemisphere surface sediment dinoflagellate cyst assemblages and their oceanographic affinities

An expanded database of Southern Hemisphere surface sediment dinoflagellate cyst assemblages and their oceanographic affinities

Initial measurement of beryllium‐9 using high‐resolution inductively coupled plasma mass spectrometry allows for more precise applications of the beryllium isotope system within the Earth Sciences

Multiple episodes of ice loss from the Wilkes Subglacial Basin during the Last Interglacial

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