Late Pleistocene Paleoceanography of the South Atlantic Sector of the Southern Ocean: Ocean Drilling Program Hole 704A

Hodell, David A

doi:10.1029/92pa02774

Cited by 61 publications

(11 citation statements)

References 58 publications

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“…Based on independent proxy records, including the deep-sea sediment record (e.g. Howard and Prell, 1992;Hodell, 1993), sea-level history (e.g. Cronin, 1981; Wornardt and Vail, 1991; Brigham-Grette and Carter, 1992) and terrestrial records of climate change (e.g.…”

Section: There Is Direct Evidence For Pleistocene Collapse Of the Wesmentioning

confidence: 99%

There is direct evidence for Pleistocene collapse of the West Antarctic ice sheet

Scherer

1993

J. Glaciol.

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lakes or the open sea within 30 km of their dolines and lateral penetration of brine may be responsible for creating paths for drainage; lateral brine infiltration has been observed several kilometres from open rifts (Thomas, 1975) in the Brunt Ice Shelf, and extensive brine layers covering tens of kilometres observed in the Larsen and Wilkins Ice Shelves (Smith, 1972). Penetration of meltwater to more than 200 m depth in ice shelves has been suggested (personal communication from A. Jenkins) as the explanation for isolated spikes in the <5 18 0 profile of an ice core from the Amery Ice Shelf (presented by Robin (1983)), that are similar to nearsurface <5 18 0 values. Therefore, direct meltwater penetration may account for drainage of the Amery Ice Shelf dolines. There is no evidence of current features on George VI Ice Shelf that could be called dolines, though there are certainly many lakes. George VI Ice Shelf was rather cold er in the 1940s and probably also in the earlier decades of the century than the present day (jones, 1990). Warmer years are mainly a result of mild winters, the summer temperatures being close to O°C. In warmer times, it is likely that much thinner surface covers of ice would form above the melt lakes, not allowing the accommodation of significant pressure from expansion of water during freezing. The water would tend to seep away gently rather than drain catastrophically, and we should expect no roof collapse or a doli ne feature to form. The occurrence of dolines on ice shelves in areas where there are substantial supplies of meltwater strongly supports the theory that dolines are melt lakes that freeze over and then suffer drainage, causing the unsupported roof to collapse. Unlike ice blisters, which usually drain through cracking of the roof of the blister forming icings, dolines probably drain through fractures in their base to the sea beneath the ice shelf.

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Section: There Is Direct Evidence For Pleistocene Collapse Of the Wesmentioning

confidence: 99%

There is direct evidence for Pleistocene collapse of the West Antarctic ice sheet

Scherer

1993

J. Glaciol.

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“…The models outlined above for fluctuating proto-AABW and proto-AAIW are applied to the age-depth data shown in Figure 7. We compare (Figure 10) our interpretation of the data (Figure 7) based on the models outlined above (Figure 8 and 9 , 1993Wright et al, 1991Wright et al, , 1992. We recognise long duration hiatuses at sites within both water masses which we suggest were a product of erosion and hiatus amalgamation.…”

Section: Application Of the Modelsmentioning

confidence: 80%

Waxing (and Waning) lyrical on hiatuses: Eocene ‐ Quaternary Indian Ocean hiatuses as proxy indicators of water mass production

Ramsay¹,

Sykes²,

Kidd³

1994

Paleoceanography

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The temporal distributions of Cenozoic hiatuses in the Indian Ocean are reconsidered in the light of a new time framework developed by the Paleoceanographic Indian Ocean Synthesis. On the basis of the temporal distribution of hiatus terminations, eight 3 m.y. time slices were selected for plotting the paleogeographical distribution of hiatus terminations. These distributions define areas of potential hiatus development, which formed along flow paths of proto‐Antarctic Bottom Water (an analogue of modern Antarctic Bottom Water) and proto‐Antarctic Intermediate Water (an analogue of modern Antarctic Intermediate Water). Expansion and contraction of these areas suggested changes in the volume of these water masses, which modified the distibution patterns of erosive deepwater currents and corrosive bottom water. Consequently, the spatial and bathymetric distribution of hiatus formation was altered. Age‐depth analysis of hiatuses from sites within post‐late Eocene areas of potential hiatus development was used, in conjunction with models of the behavior of unconformity boundaries within fluctuating water masses, to construct waxing/waning curves for proto‐Antarctic Bottom Water and proto‐Antarctic Intermediate Water. These curves define volume changes in the production histories of these water masses which were related to the post‐late Eocene glacial history of Antarctica. Since the late Oligocene, the proto‐Antarctic Bottom Water waned during intervals of increased glacial intensity, whereas the proto‐Antarctic Intermediate Water waxed during these intervals. These relationships reversed during intervals of reduced glacial intensity, including intervals where there is no evidence for Antarctic glaciation. This conflicts with interpretations made by other workers. A comparison is made between the production histories of proto‐Antarctric Bottom Water and Northern Component Water (an analogue of North Atlantic Deep Water) based on ∂13C for the Miocene to Pliocene.

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“…The peaks in accumulation rates of the above-mentioned indicators are to some extent but not completely related to glacial isotope stages: comparison of the records with the oxygen isotope data from core PC72 (Figure l a) shows that they occurred in glacials 2, 4, 6, and 8 (but were much more short-lived than glacials 6 and 8) but also in interglacials 9 and 11, which are said to represent the warmest two interglacials [e.g., Hodell, 1993]. There is no peak in accumulation rate in biogenic Ba apparent in interglacial 9, but this is probably caused by a lack of data points over the core interval with the CaC03, % Variability on timescales differing from the main glacialinterglacial 100 kyr periodicity in ice volume may explain that not all glacials at the location of TT013-PC72 were similar: during glacials 2, 4, and 6, peaks in carbonate and noncarbonate accumulation rates appear to be at least generally coeval, but during the earlier glacials and in interglacial 11, they are strongly decoupled.…”

Section: Discussionmentioning

confidence: 99%

Productivity control of fine particle transport to equatorial Pacific sediment

Thomas¹,

Turekian²,

Wei³

2000

Global Biogeochemical Cycles

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Abstract. Accumulation rates of 3He (from cosmic dust), 23øTh (produced in the water column), barite (produced in the water column during decay of organic matter), and Fe and Ti (arriving with wind-borne dust) all are positively correlated in an equatorial Pacific core (TT013-PC72; 01.1 øN, 139.4øW; water depth 4298 m). These accumulation rates are also positively correlated with the accumulation rates of noncarbonate material. They are not significantly correlated to the mass accumulation rate of carbonate, which makes up the bulk of the sediment. The fluctuations in accumulation rates of these various components from different sources thus must result from variations in some process within the oceans and not from variations in their original sources. Sediment focusing by oceanic bottom currents has been proposed as this process [Marcantonio et al., 1996]. We argue that the variations in the accumulation rates of all these components are dominantly linked to changes in productivity and particle scavenging (3He, 23øTh, Fe, Ti) by fresh phytoplankton detritus (which delivers Ba upon its decay) in the equatorial Pacific upwelling region. We speculate that as equatorial Pacific productivity is a major component of global oceanic productivity, its variations over time might be reflected in variations in atmospheric levels of methanesulfonic acid (an atmospheric reaction product of dimethyl sulfide, which is produced by oceanic phytoplankton) and recorded in Antarctic ice cores. We evaluate published data on an equatorial Pacific core and suggest a mechanism (marine productivity and particle scavenging) by which all these different data sets can be explained in an internally consistent manner. We add a 945

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Late Pleistocene Paleoceanography of the South Atlantic Sector of the Southern Ocean: Ocean Drilling Program Hole 704A

Cited by 61 publications

References 58 publications

There is direct evidence for Pleistocene collapse of the West Antarctic ice sheet

There is direct evidence for Pleistocene collapse of the West Antarctic ice sheet

Waxing (and Waning) lyrical on hiatuses: Eocene ‐ Quaternary Indian Ocean hiatuses as proxy indicators of water mass production

Productivity control of fine particle transport to equatorial Pacific sediment

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