Antarctica A Keystone in a Changing World (2008) / Chapter Skim
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A View of Antarctic Ice-Sheet Evolution from Sea-Level and Deep-Sea Isotope Changes During the Late Cretaceous-Cenozoic--K. G. Miller, J. D. Wright, M. E. Katz, J. V. Browning, B. S. Cramer, B. S. Wade, and S. F. Mizintseva
A View of Antarctic Ice-Sheet Evolution from Sea-Level and Deep-Sea Isotope Changes During the Late Cretaceous-Cenozoic--K. G. Miller, J. D. Wright, M. E. Katz, J. V. Browning, B. S. Cramer, B. S. Wade, and S. F. Mizintseva
Pages 55-70
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From page 55... ...
provide a direct record of ice tope records, both place constraints on the size and extent sheets, but these records are temporally incomplete and of Late Cretaceous to Cenozoic Antarctic ice sheets. Sea- often poorly dated and thus may not provide a complete and level records argue that small- to medium-size (typically unequivocal history, especially of initiation of ice sheets.
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From page 56... ...
. Benthic foraminiferal stable isotope data were stacked and smoothed with a Gaussian convolution filter in order to remove periods less than 1.0 myr.
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From page 57... ...
30 Maastrichtian 31 70 32 Campanian Error: 33 ±1 my; ±15 m ? 80 Late Cretaceous Santonian =25 m sea level fall Coniacian Ice thickness (m)
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From page 58... ...
There is continent-size ice sheet from 15 Ma (middle Miocene) back excellent agreement among proxies that Antarctica was in to 33.55 Ma (earliest Oligocene)
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From page 59... ...
, we argue for the likely presence of small- to mediumquartz grains in Eltanin cores from near Antarctica as reflect- size ephemeral ice sheets in the greenhouse world of the ing IRD (Figure 1) , though the evidence of this as IRD versus Late Cretaceous to Eocene.
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From page 60... ...
. Shown at right is a blowup of ODP Site 1218 oxygen isotopes that includes carbonate percentage and mass accumulation rate (AR)
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From page 61... ...
continental ice sheets grew and decayed in this greenhouse and led to the suggestion that small- to medium-size ice world, and recent sea-level studies have supported their supsheets existed in the middle to late Eocene (Browning et al., position (Kominz et al., in review; Miller et al., 2005a; Van 1996)
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From page 62... ...
. indicate minimal tectonic effects on the Late Cretaceous to We estimate Antarctic ice volume using the New Jersey Tertiary New Jersey coastal plain (Miller et al., 2004, 2005a)
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From page 63... ...
These large 18 m) sea-level falls that typified most of the Late Cretaceous O increases at 92-93 Ma and 96 Ma cannot be entirely and early Eocene, models indicate that small isolated ice attributed to ice-volume changes because this would require caps would have formed in the highest elevation of Dron- ice sheets larger than those of modern times, and in fact ning Maud Land, the Gamburtsev Plateau, and the Trans- much of the 18O signal must be attributed to deep-sea (hence antarctic Mountains (Figure 2)
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From page 64... ...
This corresponds to an Antarctic ice sheet that was icehouse conditions that began in the earliest Oligocene, the ~80-100 percent of the size of the present-day East Antarctic ice sheet reached the coastline (Figure 2) , which limited its ice sheet (today a sea-level equivalent of ~63 m is stored in further growth.
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From page 65... ...
Oxygen isotopic records indicate that the Antarctic was The Antarctic ice sheet reached the coastline for the the source of water with high 18O values in the late middle first time in the earliest Oligocene (Figure 2) and this to late Eocene (Figure 5)
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From page 66... ...
On the myr scale considered here, compensa tion was likely partially achieved (Peltier, 1997) and thus the Following the earliest Oligocene event, Oligocene to actual changes in water volume would have been higher than middle Miocene ice sheets vacillated from near modern vol- eustatic estimates.
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From page 67... ...
to Paleocene palynofloras of Seymour Island, Antarctica: ing approach to the early Cenozoic history of the Antarctic ice sheet. Implications for origins, dispersal and palaeoclimates of southern floras.
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From page 68... ...
1992. Middle Eocene to Oligocene stable isotopes, climate, and Evidence for an earliest Oligocene ice sheet on the Antarctic Peninsula.
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From page 69... ...
2005. the East Antarctic ice sheet.
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From page 70... ...
1992. Earliest Oligocene ice-sheet Late Cretaceous and Cenozoic sea-level estimates: Backstripping analy- expansion on East Antarctica: Stable isotope and sedimentological data sis of borehole data, onshore New Jersey.
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