Monts, Lee A. (1989): Late Oligocene through Quaternary shape changes in the benthic foraminiferal species Globocassidulina subglobosa (Brady), North Atlantic Deep Sea Drilling Project Site 608. 113 pp., georefid:1995-001613
Abstract:
A detailed morphometric study was conducted on the benthic foraminiferal species Globocassidulina subglobosa from late Oligocene through Quaternary sediments from North Atlantic DSDP Site 608. A total of 53 samples were analyzed via computer-assisted image analysis with the objective of extracting paleoceanographic and biostratigraphic information from morphological changes in this benthic foraminiferal taxa. The shape characteristics of G. subglobosa were quantified using Fourier Series Analysis in closed form. Maximum Entropy Analysis was then used to determine that harmonic 2 (test elongation) and harmonic 3 (test triangularity) exhibited the maximum contrast among the population examined. EXTENDED CABFAC/EXTENDED QMODEL (ECEQ) was employed to determine the number of end members within the data set and the relative proportion of each end member present in each sample. A five end member solution was chosen for both harmonic 2 and harmonic 3, capturing 98.24% and 98.12% of the variance, respectively. Many large changes are seen in the end member proportions and the mean harmonic amplitude values with respect to age (Ma). The timings of these morphological changes have been associated with several paleoceanographic events of the Neogene, including the isolation of the Mediterranean from the world ocean, uplift of the Isthmus of Panama and Northern Hemisphere Glaciation. Limited biostratigraphic ranges were also obtained from the ECEQ results, such as the unique co-occurrence of non-elongate and very elongate morphotypes during the Pleistocene. Continued research on the isotopic compositions of the different morphotypes is needed in order to acquire paleobiological information to more fully understand benthic foraminiferal population structure.
Coverage:
West: -23.0515 East: -23.0515 North: 42.5013 South: 42.5012
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