Climate in Earth History Studies in Geophysics (1982) / Chapter Skim
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Pages 172-182
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From page 172... ...
PREVIOUS WORK Before such research can proceed, quantitative data on each element of the climate system must be acquired and studied One of the most extensive quantitative data bases that now exists for the Cenozoic is the record of change in oxygen isotopes of benthic foraminifera (see Table 19.1)
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From page 173... ...
. Studies of the long-term record of the isotopic record of foraminifera, together with other geologic and geophysical studies, suggest that in the last 100 Ma there w ere two t mes when major continental ice caps were formed and extended into the sea: in the Middle Miocene, marking the buildup of the Antarctic ice cap about 14 Ma ago IShackleton and Kennett, 197Sa, 19, Sb)
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From page 174... ...
0-034 Bender (CENOP unpubl.) 208 P 1480 12 Uoiger 0 058 Bender (CENOP unpubl)
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From page 175... ...
0.013 Bender(CENOP unpubl.) 239 P 2180 36 Cibidd.
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From page 176... ...
0.015 LDutit (CENOP unpubl.j 237 1 1440 'i Oridas.
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From page 177... ...
Data derived from different species groups or size fractions were not combined, however, if their variances were not significantly different (F test) , they .,.., Water Depth, and Stratigraphic Age of Benthic Oxygen Isotope Data Used in this Study Water Stratigraphic Ocean Latitude Longitude Depth (m)
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From page 178... ...
its i_ ~ 0 10 20 30 40 AGE IlOh yr) THE LONG-TERM RECORD E Eon | Pol~cene so 30 The record of the variance in benthic oxygen isotopes is shown in Figure 19.2, with vertical lines giving the 80 percent confidence limits of the estimate and horizontal lines indicating the range of the stratigraphic age of the individual data sets Each symbol is located at the midpoint of the stratigraphic range.
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From page 179... ...
Atlantic and Southern Ocean sites show a higher variance than most Pacific sites, with the highest variances measured in the earlier part of the Late Miocene. During the Early Miocene and Oligocene, the variance of henthic oxygen isotopes in Atlantic sites were also slightly higher than those of the Pacific however, the differences are not statistically significant (F test, p > 0.9)
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From page 180... ...
In the Pacific Ocean variation in the henthic oxygen isotopes was approximately the same before arid after growth of the Antarctic ice cap. however variability in data from the Atlantic Ocean greatly increased by Late Miocene tirnff.
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From page 181... ...
itb the creation of new, isotonically different types of deep and intermediate water masses. If the later mechanism applies, large differences in the variability of benthic oxygen isotopes may be found between different oceans and between different depths in the same ocean.
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From page 182... ...
. Cenozoic pale temperatures at site 395, eastern North Atlantic: Diagenetic effects on carbon and oxygen isotopic signal, in Initial Reports of the Deep Sea Drilling Project 47, U.S.
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