Paper No. 4
Presentation Time: 1:30 PM-5:00 PM
PLANKTONIC FORAMINIFERA BIOSTRATIGRAPHY AND PALEOENVIRONMENTAL INTERPRETATION OF THE UPPER SEDIMENTARY SECTION OF CORE MD02-2560, KANE SPUR, GULF OF MEXICO
Kane Spur is located in the Gulf of Mexico southeast of the Mississippi Delta. Previous studies have shown that the history of glaciation and deglaciation of the southern area of the Laurentide ice can be reconstructed from the planktonic foraminifera record of the sediments of the Gulf of Mexico. In particular, deglaciations are interpreted by identifying times of increased abundance of warm water planktonic foraminifera, which would presumably represent times of climatic warming and input of (lower salinity) meltwater spikes. The purpose of our study is to investigate the Holocene-Late Pleistocene planktonic foraminifera record of MD02-2560 to (a) develop an age model for the upper 10 meters of the core, and to (b) interpret changes in the paleoenvironment during that time. While planktonic foraminifera biostratigraphy was developed for other core sites (e.g., MD02-2570 on the west flank of the Mississippi Canyon) from the 2002 Marion Dufresne expedition, the planktonic foraminifera biostratigraphy was not done for MD02-2560. However based on the color reflectance data we predict that the deglaciation marking the end of the Last Glacial Maximum is recorded in the sediments at nine meters below sea floor (mbsf); we will test this via planktonic foraminifera analysis. To date, 25 bulk samples were taken from core MD02-2560 between 0 and 10 mbsf and placed in a sonic bath and then sieved. Approximately 100 foraminifera were picked from each >250 micron subsample using a random picking method. The biostratigraphy is primarily based on the last occurrences (LO) of Neogloboquadrina pachyderma (dextral), Globorotalia inflata, and Globorotalia crassaformis. Changes in the abundances of Globorotalia menardii and G. inflata are being used to determine the warm and cool periods during the Late Pleistocene and Holocene.