A preliminary study of the evolution of Chiasmolithus in the middle Eocene to Oligocene of sites 647 and 748

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doi: 10.2973/odp.proc.sr.120.157.1992
Author(s): Firth, John W.; Wise, Sherwood W., Jr.
Author Affiliation(s): Primary:
Fla. State Univ., Dep. Geol., Tallahassee, FL, United States
Univ. Louis Pasteur, France
Ocean Drill. Program, United States
Univ. Claude Bernard, France
Woods Hole Oceanogr. Inst., United States
Rühr Univ. Bochum, Federal Republic of Germany
Britoil, United Kingdom
Bur. Mineral Resour., Geol. and Geophys., Australia
Ohio State Univ., United States
Univ. Toronto, Canada
Univ. Nebr., United States
Brown Univ., United States
Kobe Univ., Japan
EAWANG/ETH, Switzerland
Alfred Wegener Inst. Polar and Mar. Res., Federal Republic of Germany
Tohoku Univ., United States
Univ. R.I., United States
Aust. Antarct. Div., Australia
Lamont-Doherty Geol. Obs., United States
Mass. Inst. Technol., United States
Univ. Leicester, United Kingdom
Kyoto Univ., Japan
Volume Title: Proceedings of the Ocean Drilling Program, Central Kerguelen Plateau; covering Leg 120 of the cruises of the drilling vessel JOIDES Resolution, Fremantle, Australia, to Fremantle, Australia, sites 747-751, 20 February to 30 April 1988; Part 2
Volume Author(s): Wise, Sherwood W., Jr.; Schlich, Roland; Palmer Julson, Amanda A.; Aubry, Marie-Pierre; Berggren, William A.; Bitschene, Peter Rene; Blackburn, Neal A.; Breza, James R.; Coffin, Millard F.; Harwood, David M.; Heider, Franz; Holmes, Mary Anne; Howard, William R.; Inokuchi, Hiroo; Kelts, Kerry; Lazarus, David B.; Mackensen, Andreas; Maruyama, Toshiaki; Munschy, Marc; Pratson, Elizabeth Lewis; Quilty, Patrick G.; Rack, Frank R.; Salters, Vincent J. M.; Sevigny, James H.; Storey, Michael; Takemura, Atsushi; Watkins, David K.; Whitechurch, Hubert; Zachos, James; Barbu, Eva M.
Source: Proceedings of the Ocean Drilling Program, Central Kerguelen Plateau; covering Leg 120 of the cruises of the drilling vessel JOIDES Resolution, Fremantle, Australia, to Fremantle, Australia, sites 747-751, 20 February to 30 April 1988; Part 2, Sherwood W. Wise, Jr., Roland Schlich, Amanda A. Palmer Julson, Marie-Pierre Aubry, William A. Berggren, Peter Rene Bitschene, Neal A. Blackburn, James R. Breza, Millard F. Coffin, David M. Harwood, Franz Heider, Mary Anne Holmes, William R. Howard, Hiroo Inokuchi, Kerry Kelts, David B. Lazarus, Andreas Mackensen, Toshiaki Maruyama, Marc Munschy, Elizabeth Lewis Pratson, Patrick G. Quilty, Frank R. Rack, Vincent J. M. Salters, James H. Sevigny, Michael Storey, Atsushi Takemura, David K. Watkins, Hubert Whitechurch, James Zachos and Eva M. Barbu. Proceedings of the Ocean Drilling Program, Scientific Results, Vol.120, p.493-508. Publisher: Texas A & M University, Ocean Drilling Program, College Station, TX, United States. ISSN: 0884-5891
Note: In English. 22 refs.; illus. incl. 6 tables, 2 plates, sketch map
Summary: In this preliminary biometric study of the calcareous nannofossil species Chiasmolithus expansus, C. oamaruensis, and C. altus from the Upper Middle Eocene to Lower Oligocene of Sites 647 and 748, the authors document a complete gradation of forms among all 3 species. C. oamaruensis has significantly higher morphologic variance than the other species. The Chiasmolithus population at each site changes from C. expansus to C. oamaruensis and then to C. altus. This may not reflect a true evolutionary sequence because a major reversal in shape change of the central cross-bar structure accompanies this sequence, and because C. altus is morphologically closer to C. expansus than it is to C. oamaruensis. Reported stratigraphic and paleogeographic occurrences of C. oamaruensis and C. altus show different latitudinal distributions. These morphological and distributional patterns may be explained by a continuous morphologic gradient between C. oamaruensis and C. altus, with C. oamaruensis occurring more commonly in cool-water paleoenvironments, and C. altus occurring more commonly in cold-water paleoenvironments. Thus, paleoenvironmental fluctuations at Site 748 may be the cause of the morphologic fluctuations in Chiasmolithus. This hypothesis can be tested against previously proposed evolutionary models by more detailed sampling of sections along a latitudinal transect. (Auth. mod.)
Year of Publication: 1992
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Atlantic Ocean; Biologic evolution; Cenozoic; Chiasmolithus; DSDP Site 647; Eocene; Indian Ocean; Labrador Sea; Leg 120; Microfossils; Nannofossils; North Atlantic; ODP Site 748; Ocean Drilling Program; Oligocene; Paleobotany; Paleogene; Plantae; Species diversity; Stratigraphy; Tertiary; Thallophytes
Coordinates: S584302 S544838 E0811426 E0762427
Record ID: 1992037035
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from the Antarctic Bibliography, United States