The detailed study of an expanded Paleogene section with abundant, moderate to well preserved calcareous nannofossils from South Atlantic DSDP Site 516 has resulted in a precise correlation of most traditional and nontraditional calcareous nannofossil datums with the magnetostratigraphy. Comparison of results from Site 516 with those of previous studies for other areas enables a critical evaluation of the accuracy, synchroneity or diachroneity of the species events over geographically long distances. / ODP Leg 113 recovered the highest latitude (up to 65$\sp\circ$S) calcareous sequences in the Southern Hemisphere deep oceans. Calcareous nannofossil biostratigraphy has been established for the middle Eocene to Pleistocene sections. Correlation of the calcareous nannofossil datums with the magnetostratigraphy indicates that the last occurrences (LO's) of Isthmolithus recurvus and Chiasmolithus solitus are synchronous in the middle and high latitudes, and that the LO's Reticulofenestra bisecta, R. umbilica, R. reticulata, and the range of Chiasmolithus oamaruensis are diachronous through latitude. Bicolumnus ovatus n. gen., n. sp., is described. / Late Paleogene calcareous nannoplankton have been analyzed quantitatively for eight DSDP and ODP sites ranging from the equatorial zone to 65$\sp\circ$S latitude in the South Atlantic Ocean. This study reveals that large latitudinal biogeographic gradients had been established at least by the middle Eocene. The biogeographic gradient data conflict with the widely accepted inference from the oxygen isotopic data that the thermal gradients between mid latitudes and high latitudes are low or nearly flat for the Paleogene oceans. Lower surface water salinities in the high latitudes may have lowered the $\delta\sp{18}$O values of the planktonic microfossils, but apparently did not affect the distribution of the calcareous nannoplankton, which offers an independent means for estimating latitudinal thermal gradients. / Source: Dissertation Abstracts International, Volume: 51-01, Section: B, page: 0123. / Major Professor: Sherwood W. Wise, Jr. / Thesis (Ph.D.)--The Florida State University, 1989.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78164 |
| Contributors | Wei, Wuchang., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 361 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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