Ewa Vincent

Ewa Vincent
University of Nigeria | UNN · Department of public administration and local government

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32
Publications
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Citations

Publications

Publications (32)
Article
Cu–Ni–Sn alloys with Pb additions exhibit high mechanical strength at room temperature coupled with good machinability but experience a significant ductility loss above the melting point of lead. We explore here the influence of minor additions of Al, Mn, Zr, B or P to the copper alloy CuNi9Sn6Pb1 on its tensile properties at 400°C and 10−2s−1. Onl...
Article
Values in benthic foraminiferal delta18O records, uncorrected for temperature variations, usually remain relatively constant through the late Serravallian and early Tortonian (˜13-8 Ma) after the major early Serravallian phase of ice-sheet growth (˜15-13 Ma). This has been interpreted to indicate that ice-sheets on Antarctica had remained relativel...
Article
A clear Miocene pattern emerges in the interpretation of a Shell 2-D seismic grid correlated to two industrial wells and three ODP sites in the Maldive Inner Sea and close vicinity. A basin-wide, spectacular, and synchronous aggradations of the Maldive carbonate bank margins occurred in the late part of the early Miocene (Burdigalian; 20.5-16.4 Ma)...
Article
We have determined the abundance stratigraphy of benthic foraminifera in core ERDC 112Bx in detail, and compared it with patterns in ERDC 120Bx and PLDS 66Bx. The cores are from the western (ERDC) and eastern (PLDS) equatorial Pacific. Cluster analysis of the fauna of ERDC 112Bx yields glacial, transitional, and postglacial assemblages with boundar...
Article
Neogene calcareous sediments were recovered at 12 sites in the western Indian Ocean. Approximately 1000 10-cm 3 samples, at a sampling interval of about 1.5 m, were collected from one hole at each site for planktonic foraminifer analysis. The distribution of selected planktonic key species in each hole, a visual estimate of the abundance of various...
Data
Neogene calcareous sediments were recovered at 12 sites in the western Indian Ocean (Table 1). Approximately 1000 10-cm**3 samples, at a sampling interval of about 1.5 m, were collected from one hole at each site for planktonic foraminifer analysis. Samples were washed through a 63-?m mesh sieve. Dried samples were weighted before and after washing...
Article
An evaluation of both published and new oxygen isotope and radiocarbon data from the west equatorial Pacific (7 box cores, 2 piston cores, 2 gravity cores) indicates that there was no significant input of meltwater to the ocean before 14,000 14C yr B.P. This finding is in conflict with various early deglaciation scenarios suggested several years ag...
Chapter
There is evidence that climate pulsations during the Wisconsin-Holocene transition were accompanied by strong fluctuations in the intensity of NADW production. It appears likely that these fluctuations were largely a result of pulsed meltwater input. The production of NADW is intimately tied to global heat budget asymmetries (North vs. South, Atlan...
Article
Pulsations in the production of North Atlantic deep water (NADW) have been implicated in generating drastic climatic fluctuations during the Glacial-Holocene (G/H) transition1-3. The stable isotope record of benthic foraminifera in high-resolution cores from the Norwegian Sea suggests that such pulsations did occur4. Although the question of exact...
Article
Zusammenfassung Das Kohlenstoff-Isotopensignal in den Tiefseesedimenten spiegelt ein Zusammenspiel wider, das (1) von den globalen Austauschraten des ozeanischen Kohlenstoffreservoirs mit der Biosphäre, den Böden und den Sedimenten gesteuert wird, (2) in dem ein globaler und regionaler Wechsel in der Produktivität des Oberflächenwassers und (3) int...
Chapter
Oxygen and carbon isotope stratigraphies are presented for planktonic and benthicforaminifera from Miocene sediments of the tropical Indian Ocean (DSDP Sites 214,216, 237, 238) and placed into a biostratigraphic framework. Approximately 1000foraminiferal analyses were performed to determine both oxygen and carbon isotopicratios. The species analyze...
Article
Oxygen and carbon isotope stratigraphies are given for the planktonic foraminifer Globoquadrina venezuelana (a deep-dwelling species) at 3 DSDP sites located along a N-S transect at approx 133oW across the Pacific equatorial high-productivity zone. The records obtained at Sites 573 and 574 encompass the lower Miocene. At Site 575 the record include...
Article
The exact timing of deglaciation is an important issue in the context of climatic feedback involving the deglacial rise in atmospheric CO2 seen in ice cores1–4. We have produced evidence, from box cores taken in the equatorial Atlantic, that the last deglaciation occurred in two major steps which were separated by a brief pause5. Here we propose th...
Article
Eight box cores from the tropical Atlantic were studied in detail with regard to foraminiferal oxygen isotopes, radiocarbon, and Globorotalia menardii abundance. A standard Atlantic oxygen-isotope signal was reconstructed for the last 20,000 yr. It is quite similar to the west-equatorial Pacific signal published previously. Deglaciation is seen to...
Article
O and C istope stratigrahy of 4 DSDP sites (214, 216, 237, 238 Equatorial waters). Gs. sacculifer, D. altispira, Gq venezuelana, and Oridorsalis umbinatus (benthic) are measured. Carbon record shows a broad early-mid Miocene positive excursion in both planktic and benthic records. Begins in Chron-16; 17.5-16.5 Ma...Terminates 13.5 Ma. This shift pr...
Chapter
Oxygen isotopic analyses of planktonic foraminifera have provided a picture ofmany aspects of the evolution of the temperature structure of surface and near-surfaceoceans during the Miocene. In time slice studies oceanographic conditions have beeninterpreted from synoptic maps of isotopic data at between 22 and 27 locations in theAtlantic, Pacific...
Article
Detailed oxygen and carbon isotope stratigraphies for two species of benthic foraminifera (Planulina wuellerstorfi; Oridorsalis umbonatus) are compared between two box cores, spanning the period of deglaciation and Holocene. Within-core stratigraphies are quite well correlated, between-core signals less so. Vertical mixing and (possibly) horizontal...
Article
When ranked according to deviation from isotopic equilibrium, deep-sea benthic foraminifera exhibit no correlation between the rankings for oxygen and for carbon. Both rank sequences are stable from east to west in the equatorial Pacific (fertility-independent) and from Glacial to post-Glacial (time-independent). Records for the past 15,000 yr sugg...
Chapter
The deep-sea record shows that certain changes in the climate-producing 'exogenic' system, provoked through tectonic forces and amplified by internal feedback mechanisms, results in step-like transitions from one climatic state to another. An important step-producing mechanism is the buildup of disequilibrium potential within transient reservoirs o...
Article
Tropical Indian Ocean planktonic and benthic foraminifera have 13C/12C ratios which change abruptly within Magnetic Epoch 6 about 6.2 million years ago. All species analyzed in the Late Miocene section of DSDP Site 238 show a shift towards lighter values of δ13C by about 0.8‰. The oxygen isotope signal indicates that the pre-shift period is climati...

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