Pre‐bomb radiocarbon and the reservoir correction for calcareous marine species in the Southern Ocean

Berkman, Paul Arthur; Forman, Steven L.

doi:10.1029/96gl00151

Cited by 202 publications

(134 citation statements)

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“…is in agreement with the MRE range of 750e1300 14 C years determined in other parts of the Southern Ocean (e.g. Gordon and Harkness, 1992;Harden et al, 1992;Berkman and Forman, 1996;Domack et al, 2005).…”

Section: Methodssupporting

confidence: 76%

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

Hillenbrand

Larter

Dowdeswell

et al. 2010

Quaternary Science Reviews

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a b s t r a c tA major trough ("Belgica Trough") eroded by a palaeo-ice stream crosses the continental shelf of the southern Bellingshausen Sea (West Antarctica) and is associated with a trough mouth fan ("Belgica TMF") on the adjacent continental slope. Previous marine geophysical and geological studies investigated the bathymetry and geomorphology of Belgica Trough and Belgica TMF, erosional and depositional processes associated with bedform formation, and the temporal and spatial changes in clay mineral provenance of subglacial and glaciomarine sediments.Here, we present multi-proxy data from sediment cores recovered from the shelf and uppermost slope in the southern Bellingshausen Sea and reconstruct the ice-sheet history since the last glacial maximum (LGM) in this poorly studied area of West Antarctica. We combined new data (physical properties, sedimentary structures, geochemical and grain-size data) with published data (shear strength, clay mineral assemblages) to refine a previous facies classification for the sediments. The multi-proxy approach allowed us to distinguish four main facies types and to assign them to the following depositional settings: 1) subglacial, 2) proximal grounding-line, 3) distal sub-ice shelf/sub-sea ice, and 4) seasonal open-marine. In the seasonal open-marine facies we found evidence for episodic currentinduced winnowing of near-seabed sediments on the middle to outer shelf and at the uppermost slope during the late Holocene.In addition, we obtained data on excess 210 Pb activity at three core sites and 44 AMS 14 C dates from the acid-insoluble fraction of organic matter (AIO) and calcareous (micro-) fossils, respectively, at 12 sites. These chronological data enabled us to reconstruct, for the first time, the timing of the last advance and retreat of the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS) in the southern Bellingshausen Sea. We used the down-core variability in sediment provenance inferred from clay mineral changes to identify the most reliable AIO 14 C ages for ice-sheet retreat. The palaeo-ice stream advanced through Belgica Trough after w36.0 corrected 14 C ka before present (B.P.). It retreated from the outer shelf at w25.5 ka B.P., the middle shelf at w19.8 ka B.P., the inner shelf in Eltanin Bay at w12.3 ka B.P., and the inner shelf in Ronne Entrance at w6.3 ka B.P. The retreat of the WAIS and APIS occurred slowly and stepwise, and may still be in progress. This dynamical ice-sheet behaviour has to be taken into account for the interpretation of recent and the prediction of future mass-balance changes in the study area. The glacial history of the southern Bellingshausen Sea is unique when compared to other regions in West Antarctica, but some open questions regarding its chronology need to be addressed by future work.

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Section: Methodssupporting

confidence: 76%

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

Hillenbrand

Larter

Dowdeswell

et al. 2010

Quaternary Science Reviews

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“…In this paper, for consistency and ease of comparison, we use a uniform MRE of 1,300 (±100) 794 years (see Table 4), as suggested by Berkman & Forman (1996) for the Southern Ocean and 795 in agreement with most other studies (Table 4), thereby assuming that the MRE has remained 796 unchanged since the end of the LGM. Ideally, in order to obtain the best possible age on 797 grounding-line retreat, calcareous (micro-)fossils from the transitional glaciomarine 798 sediments lying directly above the till (i.e.…”

mentioning

confidence: 94%

Antarctic palaeo-ice streams

Livingstone

Cofaigh

Stokes

et al. 2012

Earth-Science Reviews

180

183

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We review the geomorphological, sedimentological and chronological evidence for palaeo- palaeo-ice streams to be classified into discrete retreat styles and the controls on grounding-21 line retreat to be investigated. Such analysis highlights the important impact of internal 22 factors on ice stream dynamics, such as bed characteristics and slope, and drainage basin size. 23Whilst grounding-line retreat may be triggered, and to some extent paced, by external 24 (atmospheric and oceanic) forcing, the individual characteristics of each ice stream will 25 modulate the precise timing and rate of retreat through time. ). The ability to directly observe the beds of palaeo-ice streams has also allowed 65 scientists to glean important spatial and temporal information on the processes that occurred 66 at the ice-bed interface and on the evolution of palaeo-ice streams throughout their glacial 67 history. 68Over the last two decades, there has been a burgeoning interest in marine palaeo-ice streams, and the timing and rate of deglaciation (e.g. Wellner et al. 2001;Canals et al., 2000; Lowe & 73 Anderson, 2002;Ó Cofaigh et al. 2002;Graham et al. 2009 115The first glacimarine investigations in Antarctica utilised echosounder data, till petrographic 116 studies and seismic data to reconstruct the expansion of grounded ice across the continental 117 shelf during the last glaciation (e.g. Kellogg et al. 1979; Anderson et al. 1980; Orheim & 118 Elverhøi, 1981;Domack, 1982;Haase, 1986;Kennedy & Anderson, 1989 Pudsey et al. 1994;Larter & Vanneste, 1995;O'Brien et al. 1999;Shipp et al. 1999; Canals 123 et al. 2000 Canals 123 et al. , 2002 Canals 123 et al. , 2003Anderson & Shipp, 2001;Wellner et al. 2001;Ó Cofaigh et al. 2002 Ó Cofaigh et al. , 124 2003 Ó Cofaigh et al. , 2005a Lowe & Anderson, 2003; Dowdeswell et al. 2004a,b;Evans et al. 2004Evans et al. , 2005 recently been demonstrated (Padman et al., 2010). 132In O'Brien et al. 1999O'Brien et al. , 2007 Table 2 provides a synthesis of the key physiographic data of each palaeo-ice stream in our 215 new inventory (see Fig. 1 and (ten Brink & Schneider, 1995). 228It is also apparent from 248The majority of the Antarctic palaeo-ice streams retreated across reverse slopes ( 2010) is suggested to relate to the much smaller size of its drainage basin (10,000-100,000 269 km 2 ), which is likely to have been much more sensitive to external and internal forcing. East Antarctic Peninsula, has also been associated with a change in basal processes (from 327 9 basal sliding to deformation) and an increase in ice velocity (Reinardy et al. 2011b The geometry of the basal reflector underlying the acoustically transparent unit ranges from 363 smooth and flat to irregular and undulating ( shelf (Pudsey et al. 1994Licht et al. 1996Licht et al. , 1998Licht et al. , 1999 between this bedrock and unconsolidated sediment further out on the shelf (Fig. 4c and Table 493 3) (Anderson et al. 2001; Camerlenghi et al. 2001;Wellner et al. 2001Wellner et al. , 2006...

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“…record from marine molluscs, brachiopods, echinoderms and foraminifera (Q) collected near the Antarctica (Berkman and Forman 1996), and 14C measurements on surface samples from GEOSECS, INDIGOS and CIVA1 stations (Q) near Antarctica Ostlund 1980,1983;Stuiver et al 1981;Schlosser et al 1994;Ostlund and Grall 1988). Predicted prenuclear surface 414C is ca.…”

Section: Resultsmentioning

confidence: 99%

“…Predicted prenuclear surface 414C is ca. -150% (Berkman and Forman 1996). Minima and maxima curves are drawn arbitrarily.…”

Section: Resultsmentioning

confidence: 99%

Oceanic Radiocarbon Between Antarctica and South Africa Along Woce Section 16 at 30°E

et al. 1999

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ABSTRACT. Accelerator mass spectrometry (AMS) radiocarbon measurements were made on 120 samples collected between Antarctica and South Africa along 30°E during the WOCE-France CIVA 1 campaign in February 1993. Our principal objective was to complement the Southern Ocean's sparse existing data set in order to improve the 14C benchmark used for validating ocean carbon-cycle models, which disagree considerably in this region. Measured 14C is consistent with the 0-S characteristics of CIVA1. Antarctic Intermediate Water (AAIW) forming north of the Polar Front (PF) is rich in'4C, whereas surface waters south of the PF are depleted in 14C. A distinct old 14C signal was found for the contribution of the Pacific Deep Water (PDW) to the return flow of Circumpolar Deep Waters (CDW). Comparison to previous measurements shows a 4C decrease in surface waters, consistent with northward displacement of surface waters, replacement by old deep waters upwelled at the Antarctic Divergence, and atmospheric decline in 14C. Conversely, an increase was found in deeper layers, in the AAIW. Large uncertainties, associated with previous methods for separating natural and bomb 14C when in the Southern Ocean south of 45°S, motivated us to develop a new approach that relies on a simple mixing model and on chlorofluorocarbon (CFC) measurements also taken during CIVA1. This approach leads to inventories for CIVA1 that are equal to or higher than those calculated with previous methods. Differences between old and new methods are especially high south of approximately 55°S, where bomb 14C inventories are relatively modest.

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Pre‐bomb radiocarbon and the reservoir correction for calcareous marine species in the Southern Ocean

Cited by 202 publications

References 19 publications

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

Antarctic palaeo-ice streams

Oceanic Radiocarbon Between Antarctica and South Africa Along Woce Section 16 at 30°E

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