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001 AAI3399207
005 20111205104757.5
008 111205s2009 ||||||||s|||||||| ||eng d
020 9781109657531
035 (UMI)AAI3399207
040 UMI|cUMI
100 1 Kulhanek, Denise Kay
245 10 Calcareous nannoplankton as paleoceanographic and
biostratigraphic proxies: Examples from the mid-Cretaceous
Equatorial Atlantic (ODP Leg 207) and Pleistocene of the
Antarctic Peninsula (NBP0602A) and North Atlantic (IODP
Exp. 306)|h[electronic resource]
300 210 p
500 Source: Dissertation Abstracts International, Volume: 71-
03, Section: B, page: 1583
500 Adviser: Sherwood W. Wise, Jr
502 Thesis (Ph.D.)--The Florida State University, 2009
520 This dissertation is a collection of three projects
utilizing calcareous nannoplankton as biostratigraphic and
paleoceanographic indicators. After an introductory
chapter, Chapter 2 details the results from Site 1258,
drilled during ODP Leg 207 on Demerara Rise off the
northern coast of South America. This cruise recovered
organic-rich Albian sediments that contain abundant,
moderately to well preserved calcareous nannofossils.
Biostratigraphic analysis shows the section primarily
spans Roth's (1978) middle to late Albian Zone NC9. An
unconformity separates these sediments from overlying
uppermost Albian laminated shales from Zone NC10. The
presence of Seribiscutum primitivum within the Albian
section represents the first known occurrences of this
species at such low latitudes, as Demerara Rise was
located within 15° of the equator during the mid-
Cretaceous. Its presence on Demerara Rise indicates cooler
water incursions either through changes in surface
circulation or upwelling conditions during the opening of
the Equatorial Atlantic
520 Chapter 3 details the results of a study of calcareous
nannofossils in clasts obtained during the SHALDRIL II
NBP0602A cruise to the Antarctic Peninsula. Site NBP0602A-
9 includes two holes located in the northern James Ross
Basin in the western Weddell Sea. Sediment from both holes
consists of very dark grey, pebbly, sandy mud, grading to
very dark greenish grey, pebbly, silty mud in the lower
2.5 m of the second hole. In addition to abundant pebbles
found throughout the cores, both holes contain numerous
sedimentary clasts. Biostratigraphic analysis of diatom
assemblages from the glaciomarine muds yielded rare to few,
poorly preserved diatoms that suggest the sediment is late
Pleistocene in age. The sedimentary clasts, on the other
hand, are nearly barren of diatoms, but contain rare,
moderately to well preserved calcareous nannofossils. The
clasts contain three distinct assemblages. Two clasts are
assigned an early Maastrichtian age based on the presence
of Biscutum magnum and Nephrolithus corystus, whereas one
clast is of late Maastrichtian age based on the presence
of Nephrolithus frequens. These samples also contain other
characteristic Late Cretaceous species, including Biscutum
notaculum, Cribrosphaerella daniae, Eiffellithus gorkae,
Kamptnerius magnificus, and Prediscosphaera bukryi . Two
samples contain an early Paleocene assemblage dominated by
Hornibrookina teuriensis. The Maastrichtian assemblages
are similar to those found in the Lopez de Bertodano
Formation on Seymour and Snow Hill Islands, making it the
likely source area for the Cretaceous clast material.
Although no calcareous nannofossils have been reported
from Paleocene formations on these islands, the occurrence
of calcareous foraminifers suggests other calcareous
plankton may be present; thus, the Paleocene clasts likely
also originated from the Seymour Island area
520 The fourth chapter presents results from a Pleistocene
study of calcareous nannoplankton assemblages spanning 480
--355 ka at IODP Site U1313. Calcareous nannoplankton
assemblages from Marine Isotope Stage (MIS) 12-10 record
changes in surface-water conditions over this interval.
The assemblage is dominated by family Noelaerhabdaceae,
and spans a single biostratigraphic event, the last
occurrence of Pseudoemiliania, dated to 427 ka at this
site. Most species indicate paleoecological preferences
similar to those found in the literature, although
Gephyrocapsa oceanica is more abundant during MIS 12, even
though it is thought to prefer warmer waters. Similarly,
Helicosphaera, another warm-water taxon, is also more
abundant during MIS 12. Both prefer higher nutrient
conditions that occur during the glacial stage. The first
factor of a CABFAC factor analysis explained nearly 92% of
the variability in the assemblage. This factor is
dominated by G. oceanica, and the varimax factor scores
correlate well with the alkenone-based temperature record,
suggesting that the distribution of G. oceanica at Site
U1313 is controlled by temperature. The N ratio, based on
the ratio of lower photic zone dweller Florisphaera
profunda to upwelling indicators, shows deep
stratification during much of MIS 12, usually associated
with an increase in IRD and freshwater proxies indicating
the presence of icebergs in the area. Finally, most
productivity indicators suggest higher productivity during
MIS 12, in contrast to the nannofossil accumulation rate
(NAR), which was lower during that time. Other
phytoplankton groups may have increased productivity
during MIS 12, although further work is needed to explain
why the abundance of alkenones indicates higher
productivity in the calcareous nannoplankton when the NAR
does not. (Abstract shortened by UMI.)
590 School code: 0071
650 4 Paleontology
650 4 Marine Geology
650 4 Paleoclimate Science
690 0418
690 0556
690 0653
710 2 The Florida State University
773 0 |tDissertation Abstracts International|g71-03B
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