Dominant processes of sedimentation in the west arm of Glacier Bay, Alaska.

This project will focus on sedimentary structures in the main basin of the west arm of Glacier Bay, Alaska. The objective of this study is to determine the cause of observed structures, by: (1) examining the sedimentation rate, (2) considering factors of bioturbation that would destroy physical structure, and (3) evaluating the hypothesis that biological processes dominate sedimentary structures in the west arm. Examination of sedimentary structures reveals the environmental conditions during and after sedimentation which makes environmental reconstruction possible (Reineck and Singh 1973). Accumulation rates give insight as to how fast sediment is being buried, which will help determine how fast possible toxins will be buried, as well as the fate of carbon that settles to the bottom of the fjord. Accumulation rate information determined by my project can be used as supporting data for other student projects. Benthic biological communities are also affected by the sedimentation rate (Moore 1977). Samples will be collected aboard the R/V Thomas G. Thompson, 15-26 March 2008, using both Box and Kasten cores. Plexiglas subsamplers (20cm x 30cm, ~50cm long) will be used for x-radiography and sediments will be collected at 1-5cm intervals to be processed for ²¹⁰Pb analysis (Kuehl et al. 1985). Coring and sampling procedures will be similar to that of Kuehl et al. 1985 and Jaeger and Nittrouer 1999. A necessary condition of coring is that the boat be able to hold station. ²¹⁰Pb analysis techniques will be those used by Drexler et al. 2006. While traveling to and around the stations the hull mounted EM300 broad scale bathymetry sonar and the 3.5 kHz for sub-bottom profiles will be used to map the floor of the west arm to fine tune the station sites. My mentors for this project will be Tina Drexler and Chuck Nittrouer.

Figure coming soon. Experiencing technical difficulties.  

Figure 1. Area of research will be West Arm of Glacier Bay, Alaska. Map is from USGS website.

References

Drexler, T.M., C.A. Nittrouer and B.L. Mullenbach. 2006. Impact of local morphology on sedimentation in a submarine canyon, R.O.V. studies in Eel Canyon, Northern California, U.S.A. J Sediment Res. 76: 839-853.

Jaeger, J. M., and C. A. Nittrouer. 1999. Sediment deposition in an Alaskan Fjord: Controls on the formation and preservation of sedimentary structures in Icy Bay. J Sediment Res. 69: 1011-1026

Kuehl, S.A., C.A. Nittrouer, D.J. DeMaster and T.B. Curtin. 1985. A long, square-barrel gravity corer for sedimentological and geochemical investigation of fine-grained sediments. Mar. Geol. 62: 365-370.

Moore, P.G. 1977. Inorganic particle suspension in the sea and their effects on marine animals. Oceanogr Mar Biol. 15: 224-363

Reineck, H.E. and I.B. Singh. 1973. Depositional sedimentary environments. Springer-Verlag, New York.

U.S. Geological Survey.2007. Sound waves monthly newsletter. http://soundwaves.usgs.gov /2004/06/gbay-mapLG.gif. 01/25/2008.