ENV234H1 Lecture Notes - Lecture 6: Pelagic Sediment, Alkenone, Coccolith
11 Oct 2016
School
Department
Course
Professor
Document Summary
Ranges from 1 micrometer (clay minerals) to 1000 micrometers (pteropids, other multicellular organisms) Foraminifera marine sediment that is important for reconstruction. Abundance in sediments can reach up to billions of coccoliths per gram sediment. Similar limitations: large calibration data set that covers the environmental gradient means we have to study hundreds of lakes/oceans/data. No non-analogue assemblages (outside the calibration range) cannot extrapolate. No preservational bias samples may not reflect original population (e. g. , due to erosion) cannot make assumptions. No evolutionary adaptation to other optimum conditions over time, environments change and organisms adapt; very difficult to assess. Abiotic environmental proxies stable isotope ratios: e. g. , 18o (oxygen isotope) temperature and ice volume. Element ratios: e. g. , mg/ca ratios related to temperatures, cd/ca ratios related to nutrients. Biochemical proxies (organic compounds: e. g. , alkenone related to temperature. All oxygen atoms have 8 protons but can have between 8-10 neutrons. Light oxygen-16 has 8 protons and 8 neutrons: makes up 99. 76% of all oxygen atoms.
