Climate in Earth History Studies in Geophysics (1982) / Chapter Skim
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13 Climate Acme Events in the Sea and on Land
13 Climate Acme Events in the Sea and on Land
Pages 126-132
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From page 126... ...
Haq and Lohnnann (1976) suggested that the precision with which acme horizons approximate synchronous surfaces depends on our ability unambiguously to identify the acme events (maximum geographic shifts of assemblages)
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From page 127... ...
re corded similarly low temperatures in the middle Paleocene based on oxygen isotope analyses of mollusc shells from northwest Europe. The latest Paleocene early Eocene climatic amelioration has been documented in numerous oxygen isotopic studies (Figure 13.2)
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From page 128... ...
, ~ 60 - E_i ~~j~jjjijjjjjjjjjjj9 = 0 10 At .20% PALEOCENE HIGH - LATITUDE NANNO - ASSEMBLAGE '15% EOCENE HIGH LATITUDE NANNO-AGSEMBLAGE I ~ 30% EOCENE LI LOW-LATITUDE L NANNO - ASSEMBLAGES 1 1 20 30 40 PA L SOL A T/ TUDE 60 50 60°N O 10 20 30 40 50 60°N PAL COLA T/ TUDE I .50% PALEOCENE I -MID EOCENE MID- LAT L SP SUB ASSEMBLAGE .25% MID EOCENE T ~ OLIGOCENE 11 11111 1I HIGH-LATITUDE L ~ GLOBIGERINID ASSEMBLAGE , - , .40%PALEOCENE r/////l '30%0LIGOCENE li~i~i iiiiiiiil -MID EOCENE V///~| LOW-LATITUDE L ~ ' G LOW-LA GLOBOOU4DR NID 2 At 45GEMSLTAGMEOROZOVELLID ~ ASSEMBLAGE .1 A summary of the major nannoHnral and faraminiferal migrationary patterns in the North Atlantic Ocean through the Early Cenozoic Migrations toward higher latitudes are interpreted as being caused by climatic warming and toward lower latitudes by climatic resoling. The patterns delineated enclose all samples that contain abundances greater than those indicated in the legend.
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From page 130... ...
. A temperature rise in the middle Miocene is indicated between 17-15 Ma, FIGURE 13.4 Miocene oxygen isotope stratigraphy of DSDP sites from various sources; planktonic foraminiferal cur e for DSDP sites 400 (Vergmaud-Grazzjoi es al ., 1978)
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From page 131... ...
LOW LATITUDE HIGH L ATITUVE FlGllRy 13 5 Acme horizons defined bymaximum latitudinal migrations of assemblages in response to climatic acme events Areas labeled a, b, and c delineate the latitudinal distribution of hypothetical assemblages and record latitudinal migrations of these assemblages thmuzh time Acme horizolrs 1-5 approximate isochrons and help in the stratigraphic correlation of lechers 1, 11, and 111 A given acme horizon may he defined by abundances of different as cmblages in different areas, allowing the horizon to he extended across all latitudes At a given latitude it may not be possible to identify uniquely a given acme horizon frmm the many existing within a stratigrapllic sequence Thus stratigraphic s ctions must first be approximately correlated by the usual biostratigraphic methods, ,nd then the acme horizmrs are used to refine the time stratigraphy. (After Haq and Lohmann, 1976 )
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From page 132... ...
. Paleotemperature history of the Cenozoic and initiation of Antarctic glaciation: O ygen and carbon isotope analyses in DSDP Sites 277, 279, and 281, in Initial Reports Deep Sea Drilling Praje~ct 29, U.S.
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