Paleoclimatic settings have been reconstructed for the Campanian using original oxygenisotopic analyses of well-preserved molluskan and foraminifera shells from Russian Far East, Hokkaido, USA, Belgium and some DSDP h...Paleoclimatic settings have been reconstructed for the Campanian using original oxygenisotopic analyses of well-preserved molluskan and foraminifera shells from Russian Far East, Hokkaido, USA, Belgium and some DSDP holes （95, 98, 102, 390A, and 392A） in North Atlantic. Early Early Campanian climatic optimum has been recognized from data on high bottom shelf water paleotemperatures in middle latitudes of both the western circum-Pacific （to 24.2℃） and the eastern circum-Pacific （to 26.4℃） areas and high bottom shallow water paleotemperatures in high latitudes of the Koryak Upland （22.4-25.5℃）, which agrees with the data on the Campanian Barykovskaya flora in high latitudes （Golovneva and Herman, 1998） and Jonker flora and its equivalents in middle latitudes. Judging from the data on comparatively high bottom shallow water paleotemperature values in high latitudes, South Alaska （19.4℃） and the Koryak Upland （22.4-25.5℃）, we also expect Latest Campauian temperature maximum, which has not been confirmed, however, for low and middle latitudes by neither of isotopic nor paleobotanic data now. Main dimatic tendency during the Campanian （with the exception of Latest Campanian） has been learned from isotopic composition of Campanian aragonitic ammonoid shells from the Hokkaido-South Sakhalin （Krilyon） marine basin. In contrary to Huber＇s et al. （2002） assumption, we expect warm greenhouse conditions during the most part of the Campanian.展开更多
The purpose of this study was to estimate the Coniacian latitudinal thermal gradient in the Northern Hemisphere. Both hemipelagic （ammonoids） and benthic （brachiopods and bivalves） δ18O and δ^13C records were us...The purpose of this study was to estimate the Coniacian latitudinal thermal gradient in the Northern Hemisphere. Both hemipelagic （ammonoids） and benthic （brachiopods and bivalves） δ18O and δ^13C records were used. They originated from Coniacian shallow-water sequences across a wide range of paleolatitudes, from the Koryak upland （northern Kamchatka, Russian Far East） in the north, to Hokkaido （Japan） in the south. Among Coniacian ammonoids, both migrants from Hokkaido living in high latitudes （Kamchatka） and endemic forms dwelling in middle-low latitudes （Hokkaido） indicate seemingly close optimal growth temperatures. Nevertheless, certain differences in climatic conditions, prevailing during high-latitude coldest seasons, undoubtedly provoked growth cessation in some groups of ammonites. Our isotopic study suggests latitudinal temperature changes of only 0.12 ℃ per degree of latitude for the Northern Hemisphere in Coniacian times, while the average annual temperature in North Kamchatka seems about 3.3 ℃ lower than that in Hokkaido.展开更多
文摘Paleoclimatic settings have been reconstructed for the Campanian using original oxygenisotopic analyses of well-preserved molluskan and foraminifera shells from Russian Far East, Hokkaido, USA, Belgium and some DSDP holes （95, 98, 102, 390A, and 392A） in North Atlantic. Early Early Campanian climatic optimum has been recognized from data on high bottom shelf water paleotemperatures in middle latitudes of both the western circum-Pacific （to 24.2℃） and the eastern circum-Pacific （to 26.4℃） areas and high bottom shallow water paleotemperatures in high latitudes of the Koryak Upland （22.4-25.5℃）, which agrees with the data on the Campanian Barykovskaya flora in high latitudes （Golovneva and Herman, 1998） and Jonker flora and its equivalents in middle latitudes. Judging from the data on comparatively high bottom shallow water paleotemperature values in high latitudes, South Alaska （19.4℃） and the Koryak Upland （22.4-25.5℃）, we also expect Latest Campauian temperature maximum, which has not been confirmed, however, for low and middle latitudes by neither of isotopic nor paleobotanic data now. Main dimatic tendency during the Campanian （with the exception of Latest Campanian） has been learned from isotopic composition of Campanian aragonitic ammonoid shells from the Hokkaido-South Sakhalin （Krilyon） marine basin. In contrary to Huber＇s et al. （2002） assumption, we expect warm greenhouse conditions during the most part of the Campanian.
基金supported by the International Field Expedition Programme of Japan (No. 10041109)DVO RAN (No. 09-III-A-08-402)
文摘The purpose of this study was to estimate the Coniacian latitudinal thermal gradient in the Northern Hemisphere. Both hemipelagic （ammonoids） and benthic （brachiopods and bivalves） δ18O and δ^13C records were used. They originated from Coniacian shallow-water sequences across a wide range of paleolatitudes, from the Koryak upland （northern Kamchatka, Russian Far East） in the north, to Hokkaido （Japan） in the south. Among Coniacian ammonoids, both migrants from Hokkaido living in high latitudes （Kamchatka） and endemic forms dwelling in middle-low latitudes （Hokkaido） indicate seemingly close optimal growth temperatures. Nevertheless, certain differences in climatic conditions, prevailing during high-latitude coldest seasons, undoubtedly provoked growth cessation in some groups of ammonites. Our isotopic study suggests latitudinal temperature changes of only 0.12 ℃ per degree of latitude for the Northern Hemisphere in Coniacian times, while the average annual temperature in North Kamchatka seems about 3.3 ℃ lower than that in Hokkaido.
