OCEAN 450 Lecture Notes - Lecture 7: Ice Rafting, Sea Surface Temperature, Alkenone
Document Summary
Rapid shifts between warm and cold conditions. Transition from interglacial to full glacial co(cid:374)ditio(cid:374)s is(cid:374)(cid:859)t s(cid:373)ooth. Evidence: n. atlantic sediments (ice rafted debris) and heinrich events. Episodes of higher than normal iceberg presence in n. atlantic recorded based on ice rafted debris found in ocean sediments. Heinrich events occurred at same time as cold air temperature in greenland, but not during every cold event. Evidence: greenland ice cores and sediments in n. atlantic ocean + foram species. Changes in polar (cold water) surface foram species abundance in n. atlantic ocean sediments in sync with greenland ice core air temperature shifts. Ratio of certain alkenones (lipids or fats) in plankton depends on temperature in which they grow (in lab and field) Plankton can adjust saturated v. unsaturated fats: cold = (cid:373)ore u(cid:374)saturated fats so they do(cid:374)(cid:859)t get too rigid. Measure alkenone ratio on plankton remains in sediments. Assume modern relationship holds in past to estimate sea.
