The carbon and oxygen isotopes of planktonic foraminifera, and faunal assemblages of towing samples, £_13C of dissolved inorganic carbon, and £_18O of seawater collected from northern South China Sea (SCS) were analyzed in this study. Plankton tows were collected between December 2002 and December 2005 at water depth of 100m. In addition, fauna and sea water samples were sampled at different depths ranging between 50 and 300m at some stations. Generally, the faunal assemblages are dominated by Globigerinoides ruber, Globigerinoides sacculifer, Globigerinoides aequilateralis, Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, and Globorotalia menardii. G. aequilateralis and G. menardii are dominated in warm months while G. ruber, G. sacculifer, and P. obliquiloculata are dominated in cold months. The relative abundances of G. sacculifer and G. aequilateralis obtained from towing samples in this study are significantly higher than those shown in underlying sediment traps and surface sediments, suggesting that the tests of these two taxa are prone to dissolution. In addition, the abundance of P. obliquiloculata which serves as an index taxon for the Kuroshio Current in Paleoceanography, is more abundant in the northern part than in the southern part of the SCS basin. Nevertheless, the £_13C and £_18O of G. sacculifer and P. obliquiloculata are significantly lighter than that in sediment traps and surface sediments, indicating some potential effects caused by the differential dissolution. Possible dwelling depths of P. obliquiloculata is estimated between 50 and 90m, whereas N. dutertrei is estimated between 20 and 80m according to Kim and O¡¦Neil (1997). The latter changes to 40~160m when the equation of Bouvier-Soumagnac and Duplessy (1985) is applied. Oxygen isotope compositions of G. sacculifer and G. ruber display a significant correlation with temperature (T) in the surface mixed layer. The slopes of £_18O/ T for these two species are similar to each other. The differences of £_18O (£G£_18O) between G. sacculifer and N. dutertrei, G. sacculifer and P. obliquiloculata, G. ruber and P. obliquiloculata are proved to be a good proxy indicator for reconstructing the upper water column based on the statistic relationship between £G£_18O and £GT (difference between mixed layer and 100m) in this study.

Submarine canyons are common features on continental margins worldwide. They are important natural conduits for transfer of terrigenous sediments to the deep sea, and thus, preferential pathways for shelf-slope exchange. The purpose of this study is to understand the biogenic particle transport in the seasons according two sediment trap moorings deployed in the Gaoping submarine canyon. The T6KP mooring was deployed in dry season while the T7KP mooring was deployed in wet season. Two typhoons, Kalmaegi and Fung Wong, invaded Taiwan during 16-18 and 26-29 July within the deployment of T7KP. We discussed the influence of rainfall and river discharge on biogenic particle transport based on results of the two sediment traps. The foraminiferal abundance in sediment traps in comparison with plankton tows was discussed regarding the particle transport mechanism of the water column in the Gaoping submarine canyon. The biogenic particle transport was a tide-dominated situation and displayed a periodic variation in dry season. In wet season, fine grain fraction (less than 63 micro meter) was dominant in the particle size and sedimentary condition was flood-dominated. The sedimentary condition was back to the tide-dominated state approximately 15 days after Kalmaegi typhoon (16-18, July). The activities of 210Pb and 234Th in the lower trap of T7KP mooring were an order less than that in T6KP mooring, indicating particles scavenge nuclides of the water column less effectively in wet season than in dry season. The absolute abundances of foraminifera in the canyon revealed that the biogenic particle was influenced by the terrigenous input and was different between dry and wet seasons. Seasonal variations of total flux and relative abundance of living foraminifera were evident in the upper 200 m water column near the Gaoping submarine canyon. Therefore, the seasonal variations of living foraminifera might be reflected on the biogenic particle transport in different seasons in the Gaoping submarine canyon.

Ocean acidification is occurring in response to rapidly increasing concentrations of atmospheric CO2. Shallow-water hydrothermal vent systems have been proposed as natural laboratories for studying the effects of elevated pCO2 on benthic communities. Hydrothermal vents occur at depths of approximately 10m in Tutum Bay, Ambitle Island, Papua New Guinea; these vents are surrounded by a typical-appearing fringing coral-reef community. Groups of live specimens of seven species of reef-dwelling, larger benthic foraminifers, along with segments of calcareous green algae broken from live thalli, were collected from a reef location, placed in small mesh bags, and deployed for five days at six different sites along a gradient of temperature (29.6oC-59.3oC) and pH (5.9-8.1) with distance from a large hydrothermal vent in Tutum Bay. Foraminiferal taxa used in the experiment included Amphisorus hemprichii, a species with Mg-calcite porcelaneous shells, three species of Amphistegina that produce hyaline calcite shells, and three species with hyaline Mg-calcite shells (Heterostegina depressa and two Calcarina spp.). Several specimens of four of the seven foraminiferal species examined survived exposure to elevated temperatures of 59.3oC and low pH of 6.2 for five days, while at least one specimen of each of the seven species survived exposure to 39.9oC and pH 5.9. Examination of shells at 600-1000x magnification using scanning electron microscopy revealed fine-scale dissolution in specimens up to 30m from the vent. Results of this experiment, as well as previously reported observations from the study site, indicate that the calcifying reef-dwelling organisms examined can survive pH extremes that result in dissolution of their shells following death.

Στην παρούσα εργασία εξετάζονται οι συγκεντρώσεις των πλαγκτονικών τρηματοφόρων, όπως αυτές έχουν καταγραφεί σε δημοσιευμένες εργασίες και ανάλογες επιστημονικές βάσεις δεδομένων από την περιοχή της Μεσογείου για το χρονικό διάστημα των τελευταίων 18.000 χρόνων. Με σκοπό να εξεταστούν τυχόν χωρικές και χρονικές μετατοπίσεις των ελάχιστων και μέγιστων των συγκεντρώσεών τους και διαφοροποιήσεις τους σε σχέση με τις σημερινές. / In the present work the concentrations of planktonic foraminifera, as recorded in published papers and similar scientific databases from the Mediterranean region for the period of the last 18,000 years. To examine any spatial and temporal shifts of the minimum and maximum concentrations of these differences and their relationship to current.

Hurricanes are amongst the most devastating of the world’s natural disasters and can cause billions of dollars’ worth of damage every year. Efforts to predict where and when tropical cyclones might strike, then, could potentially save money and lives. A lack of data exists for the GA coast, and the future direction of climate change could potentially bring more hurricanes to the state. This study provides information to enhance the paleohurricane record by examining three vibracores drawn from St. Catherines Island, GA. After interpreting the environments that generated the sediment found in one of these cores and corroborating evidence from the additional cores, six potential hurricane events were discovered, five of which were likely major hurricanes, category 3 or higher. Magnitudes were determined by comparison to event six, thought to be “The Great Gale of 1804”, a major hurricane recorded by the sedimentary record of St. Catherines Island.

Underwater (phreatic) caves are a ubiquitous landform on coastal karst terrain, but the marine geological processes operating in these systems are largely unknown. This dissertation redresses the problem by asking if Bermudian phreatic cave sediments archive sea-level and climate information? An important premise is that coastal cave environments are not identical. They can be categorized based on whether they are terrestrially-influenced (anchialine), completely flooded by saline groundwater (submarine), positioned at sea level (littoral) or in the vadose zone (vadose). For the first time the boundary between modern anchialine and submarine cave environments has been distinguished in Green Bay Cave using a multi-proxy approach (benthic foraminifera, sedimentary organic matter content and carbon isotopic composition - ?13Corg, and grain-size analysis). Twelve push cores were extracted from Green Bay Cave and dated with twenty 14C dates, recovering the first underwater cave succession spanning the Holocene (13 ka to present). Green Bay Cave transitioned through all major cave environments during Holocene sea-level rise (vadose, littoral, anchialine, and submarine), providing a sedimentary model for global cave successions. These relationships provide a novel means to solve Quaternary sea-level and climate problems. For sea level, two examples indicate that the littoral cave can be used as a sea-level indicator, distinguished stratigraphically by microfossil or sedimentary proxies. First, the elevation and timing of when Green Bay Cave was a littoral environment indicates Bermuda experienced an abrupt ~6.4 m sea-level rise at 7.7 ka, coinciding with final collapse of the Labrador sector of the Laurentide Ice Sheet. Second, microfossils preserved in elevated caves at +21 m above modern sea level and dated to marine isotope stage 11 (U-series, amino acid racemization) are consistent with modern Bermudian caves and co-stratigraphic sea level. For climate problems, annual temperature monitoring in Walsingham Cave indicates that cave water is thermally comparable to regional oceanographic conditions in the Sargasso Sea. Three sediment cores dated with sixteen radiocarbon dates indicate that Bermuda’s coldest and stormiest conditions of the last 3.2 ka occurred during the Little Ice Age (proxies: ?18Oc, grain size, bulk organic matter).

No description available.

Foraminiferal faunas across the early to middle Eocene transition (EMET) were studied from three locations in the western Caribbean: Calle G section in Cuba, ODP site 998 B the Cayman Rise, and ODP site 999 B the Colombian basin. There were three primary objectives of this project 1) to observe changes in physical and biological paleoceanographic parameters in the Western Caribbean, more directly in the Cayman Ridge and the Colombian Basin, by the use of planktonic foraminifera data, 2) determine the cause of an oxygen isotope anomaly seen in Cuba by Fluegeman (2007) and that is expected to be present in the Western Caribbean, and 3) determine if the anomaly is a local or a more widespread regional event. The Calle G section in northwestern Cuba consists of early to middle Eocene age foraminiferal chalks. The planktonic foraminiferal fauna at this section is characterized by subbotinids and acarininids but does not contain morozovellids. Oxygen isotopes were obtained across the EMET from the planktonic foraminiferan Acarinina collactea. The resultant curve shows widely fluctuating values during the early portion of the EMET with more stable values occurring in the middle Eocene. The foraminiferal paleoecologic index tau curve at the Calle G section produced is similar to the oxygen isotope curve. ODP site 998 B, Cayman Rise, contains a series of foraminiferal limestones across the EMET. Unlike the Calle G section, this interval contains an abundant planktonic foraminifera fauna including Morozovella. The Morozovella:Acarinina ratio studied at ODP site 998 shows high, fluctuating values in the early part of the EMET with low, stable values during the middle Eocene.ODP site 999 B in the Colombian Basin consists of a series of foraminiferal chalks throughout the EMET. Similar to ODP site 998 this location also has an abundant assemblage of planktonic foraminifera including Morozovella. Evidence supporting turbidities have been observed at this locale as layers of shell hash and large benthic foraminifera. The Morozovella:Acarinina ratio studied at ODP site 999 is similar to that of ODP site 998 showing a high fluctuating values in the early part of the EMET with low, stable values in the middle Eocene. The presence of fluctuating values of oxygen isotopes, tau, and the Morozovella:Acarinina ratio followed by stable values across the EMET may be related to a change in circulation patterns through the Caribbean caused by a developing oceanic gateway. The widely fluctuating oxygen isotope values in the latest Ypresian may also be related to an influx of freshwater in the North Atlantic associated with the coeval Azolla event in the Arctic Ocean. / Department of Geological Sciences

Thesis (M. Sc.)--Carleton University, 2004. / Includes bibliographical references (p. 66-77). Also available in electronic format on the Internet.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 68-72). Also available on the World Wide Web.