Dixon, Julie E. "Circulation Processes in Lapeyrere Bay, Anvers Island, Antarctica, and Implications in the Event of Petroleum Pollution," May 1991, Hamilton College.

Franceschini, Jordan "Preservation of Total Organic Carbon in Sediments from the Ross Sea, Antarctica," April 1995, Hamilton College

Hilfinger, Martin "Chronology of the Late Pleistocene-Holocene Deglaciation in the Ross Sea," April 1995, Hamilton College

Kirby, Matthew E. "High Resolution Seismic Stratigraphy and Sedimentological Analysis of Holocene Glacial Marine Sediments in the Palmer Deep Basin, Bellingshausen Sea, Antarctica," May 1993, Hamilton College.

LoPiccolo, Matthew "Productivity and Meltwater Cycles in Andvord Bay, Antarctica: Evidence of High Frequency Paleoclimactic Fluctuations," April 1996. Hamilton College

Mammone, Kerry A. "Modern Particle Flux and Productivity in Andvord Bay, Antarctica," December 1992, Hamilton College.

Mashiotta, Tracy A. "Biogenic Sedimentation in Andvord Bay, Antarctica: a 3,000 Year Record of Paleoproductivity," April 1992, Hamilton College.

McElroy, H.G. "Cyclical preservation of organic matter in Andvord Bay, Antarctica," April 1994, Hamilton College

Rodriguez, A.B. "A Geochemical Sedimentological Analysis of Glacial Marine Sediments from the Palmer Deep Basin, Bellingshausen Sea, Antarctica," April, 1994, Hamilton College

Seidner, John D. "A General Analysis of the East Antarctic Continental Shelf Modern Radiolaria and Their Relashonship to Circumpolar Deep Water," April 1992, Hamilton College

Shevenell, Amelia E. "Record of Holocene Paleoclimate Change Along the Antarctic Peninsula: Evidence from Glacial Marine Sediments, Lallemand Fjord," April 1996, Hamilton College

Stein, Andrew B. "Growth of the Muller Ice Shelf During the Later Half of the Little Ice Age as Documented by Glacial Marine Sediments and Radiogeochemistry," April 1992, Hamilton College.

Straten, Brett T. "Evidence for Gravity Flows as Sediment Transport Systems from High Resolution Seismic Data and Piston Cores taken from Admiralty Bay, King George Island, Antarctica," April 1996, Hamilton College

Williams, Chesley R. "Temperature and Sediment Characteristics of a Polar Fjord: Cierva Cove, Antarctica," May 5 1989, Hamilton College

Williams, E.T. "The Introduction and Dispersal of Suspended Sediment from the Cayley Glacier in Brialmont Cove, Antarctica," April, 1994, Hamilton College

Abstracts

The current level of development on the Antarctic continent makes a detailed inspection of the potential impact of man on the environment a necessity. The fjords along the antarctic peninsula are likely areas for development, being deep enough to accommodate larger vessels and sheltered from the elements by their protected geography. Critical to the assessment of environmental impacts is the pattern and nature of fjord circulation. The focus of this paper is the surface circulation processes in Lapeyrere Bay, a fiord on Anvers Island in the Palmer Archipelago. Data was collected during the summer melt season, in December, 1987, and January, 1988. (Antarctic Journal, 1988, and unpublished cruise report) A bathymetric chart was compiled from cruise track data. Meltwater from the surrounding glaciers, when present, was not found to play a larger role in circulation. In contrast, iceberg melt affected surface temperatures and salinity by as much as 1 ¡C and 1.2 ppt. in the upper 15 meters of the water column. Using criteria developed by Shen, Yapa and Petroski (CRREL report 90-1, 1990) and others (Wheeler, 1978, and Exxon Background Series, 1978), it was found that an oil spill in a sub-polar fjord such as Lapeyrere Bay could have potentially devastating effects, since the rate ot spreading and chemical and biological degradation are strongly influenced by the season, weather, and amount of ice in the fjord. To advance the current understanding of the circulation processes operating in the bay, more research needs to be done at different times of the year. Although research in the wintertime is impossible, a visit to the fjord in early spring or late summer - in the months of October or April - would further knowledge. More research also needs to be done to determine the effect of polar and sub-polar conditions on the dispersal rates of oil spills.

12 sediment cores from the Ross Sea, Antarctica, are analyzed to test the hypothesis of deglaciation of the West Antarctic Ice Sheet, its timing, and to search for possible causes of the glacial retreat. The methodology of this investigation includes total organic carbon, magnetic susceptibility, radiocarbon dating, and gravel frequency. The data demonstrate that the West Antarctic Ice Sheet grounded on the continental shelf during the last glacial maximum approximately 17,000 years ago. The cores penetrated a diatomaceous mud resting on a sharp contact with glacial marine sediments indicating that the change from subglacial sedimentation to hemipelagic sedimentation occurred rapidly. Total organic carbon data demonstrates the retreat of the ice sheet, along with a period of elevated carbon percentages in the sediment which could possibly represent the Hypsithermal. The data shows that recession of the ice shelf began about 19,000 years ago which is a little earlier than some previous research. The retreat is believed to have been triggered in response to a rise in sea level due to deteriorating ice sheets in the northern hemisphere. Mechanisms for retreat indude rapid and episodic rise in sea level, and global climatic fluctuation.

Our results indicate that ice sheet recession in the central Ross Sea began around 19,000 yrs BP. Completely open marine conditions occurred here by 6,700 yrs BP. The maximum age corresponds relatively well to the beginning of eustatic sea level rise, which according to Fairbanks (1989) occurred around 17,100 yrs BP. Continued study of Ross Sea cores will allow a better understanding of relationships between sea level rise and ice sheet recession.

The Palmer Deep is located along the West coast of the Antarctic Peninsula on the Bellingshausen Sea continental shelf, five kilometers south of Anvers Island. The maximum depths of 1440m and the enclosed complex bathymetry make the Palmer Deep Basins an excellent source for sedimentological studies. The focus of this report is the analysis and interpretation of the bathymetry, HUNTEC high resolution seismic profiles, and four piston cores. Multiple tests were performed on these cores revealing a correlative magnetic susceptibility shift (ms) and lithologic change at about mid-core. Similar transitions were observed in other tests, including % biogenic silica, CaCO₃, C¹⁴ (sedimentation rates) and smear slide examination of quartz/diatom ratio. In addition, the HUNTEC seismic profiles show acoustic reflectors at depths corresponding to these sedimentary horizons. Comparisons between other cores from Andvord Bay show the same ms and lithologic changes observed in the Palmer Deep. Recent climatic cooling to the present day conditions is one hypothesis used to explain this shift. In addition to the multiple indicators of climate, mud turbidite sequences are observed in the cores from the deepest basin of the Palmer Deep. The presence of five turbidite sequences in a core, dating back 5000 years at maximum, suggests low frequency but high energy events are responsible for initiating these deposits. Large storms, ice berg groundings, and tsunami events are considered as possible trigger mechanisms. Further study is needed, however, for a satisfactory understanding of the sedimentary history the Palmer Deep area.

A detailed grain size analysis was conducted on samples from a 9m-long piston core collected during cruise PD 87-III in Andvord Bay, Antarctica. Samples were analyzed using a Malvern Master Sizer E over the .1-80 micron size range. Core 22 is composed primarily of medium to fine grained silt (approximately 65%). Results were compared to total organic carbon (TOC) and magnetic susceptibility (MS) data acquired in 1992 from the same core. Previous research indicated that TOC and MS fluctuated in a cyclical fashion so that approximately 13 cycles were recognized over a 3000 year period. Comparison of the grain size data with the TOC data showed that each of the 13 carbon peaks preceded a peak of medium-fine grained silt with varying lag times between the two parameters. Lag times, determined by using a linear sedimentation model for the core (Mashiotta, 1992), ranged from 22 years to 146 years. These results suggest that, as atmospheric temperatures increased, sea surface temperatures increased relatively quickly, thus, stimulating productivity and higher carbon preservation. However, terrigenous sedimentation, controlled by glacial meltwater, increased at decadal to century scale rates, as the sub-polar glacial systems supplying meltwater responded gradually to atmospheric temperature variations. The common cyclical pattern found in the data set provides strong evidence for paleoclimatic fluctuations within both the oceanic and glacial systems along the Antarctic Peninsula. These operate in the 200-300 year frequency band similar to century scale solar variability.

Sediments from the trap were found to be rich in both organic carbon (3-5 wt %) and biogenic silica (23-31 wt %). Textural analysis shows the ice-rafted debris to be relatively constant throughout the water column and to account for a much smaller percentage of material than the biogenic matter. The total sediment flux was found to increase dramatically with depth. The near bottom trap (441 m water depth), although it has the highest total flux, was found to be deficient of a coarse-grained fraction and of total organic carbon weight percent. The pronounced increase of fine grained terrigenous sediment unique to this trap is probably a result of resuspension of near-bottom material. The biogenic flux, an indirect measurement of primary productivity, of Andvord Bay. has been determined to be significantly higher than other areas of the Antarctic. When compared with a previous study of productivity as preserved in a sediment core conducted in Andvord Bay, the modern biologic flux is characteristic of a climate and productivity similar to that found approximately 2,700 years B.P..

Biogenic silica analyses were conducted on samples from a piston core (#22) collected in Andvord Bay, Antarctica, to examine the relationship between paleoclimate and primary productivity, and to predict the effects of global warming on productivity within the fjord environment. Forty-six samples were collected from the 900cm core and analyzed for bulk density and biogenic silica. Weight percent biogenic silica results range between 12% and 21%. The sedimentation rate within Andvord Bay was determined based on Carbon-14 Accelerator Mass Spectrometry dates of five samples from the core. Core 22 represents approximately 3,000 years, from 133 to 3,115 years B. P. Preserved flux rates of biogenic silica and carbon were calculated, and found to be significantly higher than flux rates from other areas within the Antarctic. The biogenic silica flux in Andvord Bay ranges between 166 and 762 g/m²/yr, and the carbon flux between 11 and 57 g/m²/yr. It is believed that these high flux rates, which may result from the unique, isolated morphology of Andvord Bay, are indicative of high rates of primary productivity within Antarctic subpolar fjords. Maximum rates of productivity are assumed to have occurred during a warmer climate, when the sea ice cover was less extensive spatially and temporally, and receipt of solar radiation by the surface water column was greater. Based on the changes in weight percent biogenic silica and total organic carbon between 133 and 3,115 years B. P., it appears that a 2¡C increase in global temperatures over roughly a 150 year period caused an increase in productivity of only 4 percent.

Evidence for 300 year cycles of preserved organic matter was found in a sediment core taken from Andvord Bay on the western Antarctic Peninsula. Further evidence of this cyclicity from other sediment cores is necessary to verify the cycle's existence and to determine its cause. This study is aimed at finding data to support the suggestion that a 300 cyclicity does exist in Antarctic fjord sedimentary sequences; and, through an understanding of the parameters which affect phytoplankton productivity and preservation, determining what causes these cycles. Data is obtained through an analysis of a second sediment core, also taken from Andvord Bay. The methodology of this investigation includes measuring the second core's total organic carbon content and magnetic susceptibility. If a thorough understanding of these cycles can eventually be attained, a basic knowledge of rapid change within Antarctic productivity could be assumed. This knowledge of fine scale fluctuations could contribute to the interpretation of future climatic changes and lead to an increased understanding of climatic change. On a smaller scale, the fluctuations could help predict what effects global warming may have on the biological communities in polar regions, especially at the primary level.

Glacial marine sediments were examined from the Palmer Deep, located along the West coast of the Antarctic Peninsula on the Bellingshausen Sea continental shelf, five kilometers south of Anvers Island. Magnetic susceptibility, total organic carbon, and elemental analysis were performed on the core. The focus of this study is the analysis of magnetic susceptibility fluctuations in the top 625 cm of the core. High magnetic susceptibility indicates high hemipelagic sedimentation and low magnetic susceptibility indicates high pelagic sedimentation (productivity). Evidence for the type of variations in sedimentation being displayed by fluctuations in magnetic susceptibility is presented by: (1) the observations that total organic carbon varies inversely with magnetic susceptibility, (2) the plots of Sr, Al₂0₃, CaO, K₂O, MgO, TiO₂, versus magnetic susceptibility and total organic carbon portray distinct positive and negative sloping trends, and (3) the plot of SiO₂ versus magnetic susceptibility and total organic carbon portray distinct negative and positive sloping trends. Possible events that explain these sedimentation cycles are periods of large storms.

This study is the first one to investigate the character of these radiolarian assemblages on the Antarctic shelf proper. The initial findings are promising and indicate that further investigation of these radiolarian assemblages may find a correlation between the radiolarian assemblages and the warm CDW tongues.

In light of recent warming and environmental changes observed on the Antarctic Peninsula (Leventeretal., in press), an increased knowledge of regional paleoclimatic trends may provide an improved understanding of the expected response of the Antarctic glacial, oceanic, and biotic systems to continued regional warming. Sedimentologic and geochemical analyses of a 5.5 m long, high resolution sediment gravity core collected in Lallemand Fjord, Antarctica represent the most complete stratigraphic record of Holocene climate change, to date, in Antarctica. Grain size, magnetic susceptibility, and total organic carbon content (T.O.C.) were measured in PD92-2 GC-1. Three distinct sedimentologic units believed to reflect distinct paleoenvironments in the fjord were recognized. A well constrained radiocarbon date on an in situ Scaphopod was used to establish a carbon chronology for the core extending through 90% of the Holocene. Deglaciation of Lallemand Fjord is believed to have occurred prior to ¹⁴C 8000 year BP: followed by a period of open marine conditions with variable sea ice extent (variable T.O.C. content) between 8000 and 2700 ¹⁴C years BP. Around 2700 14C years BP, a shift to ice proximal sedimentation reflects the formation of more extensive and seasonally persistent sea ice. The Muller Ice Shelf, now present in the fjord, advanced approximately 400-500 years ago coincident with the Little Ice Age (LIA) (Domack et al., 1995). Results indicate environmental variability throughout the Holocene; interpreted as reflecting the variability of the Holocene climate. Timing of the transitions correlates with northern hemisphere "T-Events" and ice core data from Greenland (GISP2), indicating the possibility of coherent climate variability in the Holocene, at least for the high latitudes.

The Antarctic Peninsula provides a unique location for monitoring environmental conditions as climatic fluctuations serve to accentuate variations in the geologic record. This paper utilizes an environmentally sensitive ice shelf in a region along the Western Coast of the Peninsula to exhibit the significance of these fluctuations. From 2 Kasten Cores collected on Polar Duke Cruise 90-7 in Lallemand Fjord, evidence suggests the Muller Ice Shelf has migrated during the last 600 years over one of the core sites. The Muller Ice Shelf survives in a fragile environment as it is believed to be the northernmost shelf on the peninsula, establishing it as a valuable and sensitive tool for environmental deviations. More specifically, from approximately 1200 AD to 1650 AD, eolian sediment deposition and Total Organic Carbon values indicate an open marine environment throughout the fjord as the ice shelf retreated shoreward. Sediment analyses indicate a pronounced progradation of the Muller Ice Shelf through the Little Ice Age to approximately 1860 AD. Eolian debris were deposited in the fjord facilitated by the extension of the Muller Ice Shelf which transported sediments over the calving line and into the marine environment. Further variation in the sediment record demonstrates another regression of the Muller Ice Shelf after it reached its maximum during the Little Ice Age at 1860 AD as sediment levels decreased. Up to 1974, continued growth of the shelf has been documented by sediment and visual observations. After this time, the Muller Ice Shelf has continued to disintegrate to its present day location. This paper utilizes sediment grain size, Total Organic Carbon, and Pb-210 analyses in an attempt to support these contentions.

Admiralty Bay is located on the southern end of King George Island, the largest island of the South Shetland Island chain. Although Admiralty Bay is a location of intensive scientific research, most of this research focuses on the biological processes in the bay and little is known about sediment transport within the fjord. This report will focus on interpreting the HUNTEC high resolution seismic profiles and two piston cores to gain a better understanding of the processes of sedimentation within the fjord. Analyses were done on two cores, PD88-176 and PD92-19, including grain size, magnetic suspectilbility, and grain count analysis. Four ¹⁴C dates were also obtained from core PD176-88 at depths. The cores consist of high amounts of terriginous sediment ranging in size from very fine grained sandy mud to very fine grained sand. After interpreting both the cores and the seismic data a theory for sedimentation was developed. Sediments deposited at the head or sides of the fjord are periodically carried into the trough of the fjord by slumping. The HUNTEC seismic profiles shows evidence for several large slump blocks. After sediments are deposited into the bottom of the trough they move down fjord in infrequent gravity flows, possibly initiated by subaerial seismicity. Sediments may also be reworked and redeposited by strong bottom currents. Without a large sill to capture sediments at the entrance of Admiralty Bay, it is possible for sediments to be transported into King George Basin (a deep basin of the Bransfield Strait) by both sediment gravity flows and large bottom currents.

An understanding of temperature and sediment characteristics of polar and subpolar fjords is very important in understanding the effects of man's development of the remote polar regions. This paper analyzes Cierva Cove, an Antarctic Fjord, for its particular characteristics of circulation and sedimentation. Weak estuarine surface circulation is observed as well as a tongue of cold water extending from the glacier's base through the mid-water depths. One possible explanation for this feature is that it is related to tidally induced glacial movement. There is no circulation observed in the deeper bottom waters in the two basins found in Cierva Cove. The oceanographic evidence seems to supports the view that Cierva Cove lies on a climatic boundary between polar and subpolar environments since it contains circulation patterns characteristic of both these types of systems.

The results show different terrigenous sedimentation processes to be dominant at various depths and that tidal flushing (Domack and Williams, 1990) may have an integral role at bottom depths. As a result of the open bay physiography in Brialmont Cove, the meltwater plumes entering into the head of the cove from the Cayley Glacier are strongly influenced by the Coriolis Effect. This effect directs the meltwater plume into the western region of the cove, and subsequently drives a clockwise circulation system. The western side of the cove is consequently dominated by cool, relatively fresh meltwater, while the eastern poffion of the cove is dominated by warmer, higher salinity outer bay water.

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Created by:
Jonathan Marcel
Last Modified: 12/21/96