Paleocene planktonic foraminifers of the subantarctic South Atlantic
Paleogene planktonic foraminifers recovered during ODP Leg 114 in the subantarctic region exhibit a cosmopolitan character at the opening of the Paleocene, and then they evolve similarly to faunas from lower latitudes. They begin to differentiate from lower latitude faunas by the early late Paleocen...
| Main Authors: | , , |
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| Format: | Other/Unknown Material |
| Language: | English |
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PANGAEA
1991
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| Subjects: | |
| Online Access: | https://doi.pangaea.de/10.1594/PANGAEA.755560 https://doi.org/10.1594/PANGAEA.755560 |
| Summary: | Paleogene planktonic foraminifers recovered during ODP Leg 114 in the subantarctic region exhibit a cosmopolitan character at the opening of the Paleocene, and then they evolve similarly to faunas from lower latitudes. They begin to differentiate from lower latitude faunas by the early late Paleocene when large morozovellids disappear from the region and cool deep-water-dwelling Globorotaloides appear much earlier than at lower latitudes. By early Eocene time large morozovellids immigrate into the subantarctic area during the warmest episode of the entire Eocene. From that time up to the end of the middle Eocene planktonic foraminiferal faunas exhibit a temperate character, as indicated by the abundance of common acarininids. At the same time dissolution at depth causes depauperated planktonic faunas at the deeper sites. A new warming episode during the late Eocene is marked by the immigration of Globigerinatheka luterbacheri into the subantarctic region. The cooling trend during the late Eocene causes a progressive decrease in species richness, which only sporadically is less than 10 species. The early Oligocene is also characterized by relatively rich planktonic faunas, but after that time the western subantarctic region is occasionally invaded by few planktonic foraminiferal species. These immigrations coincide with the warmer episodes on the climatic curve, such as Zones P21a and P22-"N4." Beginning in late early Eocene and through the Oligocene eastern subantarctic planktonic foraminiferal faunas exhibit a much warmer character than those from the western side and are more similar to warm temperate faunas. Therefore, the eastern faunas provide a more refined biostratigraphy. Oligocene time is characterized by a trend toward a warmer climate; however, this trend was reversed in the early Miocene. A dissolution event, possibly coeval with an erosional event, occurs within Zone P21b across the subantarctic region. |
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