Biogeographic reconstructions for the North Pacific Oligocene shelf zones: comparison of “warm” Eocene and “cold” Oligocene
نویسندگان
چکیده
منابع مشابه
Erosion and reworking of Pacific sediments near the Eocene- Oligocene boundary
[1] The Eocene-Oligocene (E/O) boundary interval marks one of the largest and most rapid changes in climate during the last 50 Myr. Because of a very shallow calcium carbonate compensation depth in the Eocene, as well as the reworking of sediments and hiatuses in the boundary zone, it has also been one of the most difficult stratigraphic boundaries to study in deep water marine sections, especi...
متن کاملRevised Eocene-Oligocene kinematics for the West Antarctic rift system
[1] Past plate motion between East and West Antarctica along the West Antarctic rift system had important regional and global implications. Although extensively studied, the kinematics of the rift during Eocene-Oligocene time still remains elusive. Based on a recent detailed aeromagnetic survey from the Adare and Northern Basins, located in the northwestern Ross Sea, we present the first well-c...
متن کاملEnrichment of dissolved silica in the deep equatorial Pacific during the Eocene-Oligocene
Silicon isotope ratios (expressed as δSi) in marine microfossils can provide insights into silica cycling over geologic time. Here we used δSi of sponge spicules and radiolarian tests from the Paleogene Equatorial Transect (Ocean Drilling Program Leg 199) spanning the Eocene and Oligocene (~50–23 Ma) to reconstruct dissolved silica (DSi) concentrations in deep waters and to examine upper ocean ...
متن کاملGEOLOGICAL NOTES Regional Paleoprecipitation Records from the Late Eocene and Oligocene of North America
The marine dO record indicates precipitous cooling or significant expansion of Antarctic ice volume across the Eocene-Oligocene epoch boundary at 33.7 Ma. This climatic step is also found in estimates of decreased paleoprecipitation from paleosols in Oregon, Montana, and Nebraska but is only a part of a long-term decline across the Eocene-Oligocene transition rather than a sudden shift. This su...
متن کاملGlobal cooling during the eocene-oligocene climate transition.
About 34 million years ago, Earth's climate shifted from a relatively ice-free world to one with glacial conditions on Antarctica characterized by substantial ice sheets. How Earth's temperature changed during this climate transition remains poorly understood, and evidence for Northern Hemisphere polar ice is controversial. Here, we report proxy records of sea surface temperatures from multiple...
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ژورنال
عنوان ژورنال: BULLETIN OF THE GEOLOGICAL SURVEY OF JAPAN
سال: 2009
ISSN: 1346-4272
DOI: 10.9795/bullgsj.59.301