CLIMATE CHANGE IN THE NORTH ATLANTIC OCEAN (IODP EXPEDITION 306, SITE U1314) AT CA. 1.5 MA

Integrated Ocean Drilling Program (IODP) Expedition 306 examined the climatic and paleoceanographic history of the North Atlantic Ocean. The North Atlantic Ocean is well known for its sensitivity to climatic fluctuations through time. This study focuses on Pleistocene sediment samples from cores recovered from Site U1314. Site U1314 is located southeast of Greenland and south of Iceland on the southern part of the Gardar Drift, just north of the classic IRD (ice-rafted debris) belt. Some of the recovered sediment from U1314 was the product of IRD, which is sand- to gravel-sized sediment that was transported by icebergs as they floated across the North Atlantic Ocean. The purpose of this study is to record information collected from this Pleistocene IRD and then obtain a glacial climate history for the North Atlantic Ocean approximately 1.5 million years ago.

Samples used in this study were obtained from the IODP Bremen Core Repository. Approximately 10 cc of sediment was collected for each sample at a resolution of one sample every 1500-2000 years. In order to extract the IRD from the sediment, each sample was initially dried, weighed, and wet-sieved at both 150 ìm and 2 mm. This >150 ìm size-fraction defines the IRD for this study. Samples were then dried and weighed once more. Sieve data was analyzed descriptively through graphical representation. Preliminary results suggest that the sediment from U1314 records intervals of more intense IRD accumulation and other intervals dominated solely by biogenic components in the >150 ìm size-fraction. The IRD has been examined using a binocular microscope in order to identify the composition of the lithic grains, and a variety of compositions have been noted, including the presence of basalt, quartz (including rose quartz), obsidian, sandstone, and schist. By extracting the IRD from U1314 sediment, we can reconstruct climate histories in the region, determine provenance regions, and calculate the rate at which the IRD was deposited on the Gardar Drift.