Characterisation of sedimentary organic matter by bulk and molecular geochemical proxies: an example from Oligocene maar-type Lake Enspel, Germany
✍ Scribed by Guido Lüniger; Lorenz Schwark
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 533 KB
- Volume
- 148
- Category
- Article
- ISSN
- 0037-0738
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✦ Synopsis
Characterisation of organic matter composition of fossil lake sediments is important in reconstruction of fossil ecosystems and paleoclimates. High time-resolved organic matter analysis is needed to characterize sediments from small lake environments, due to their rapidly changing environmental conditions. A suitable technique for rapid analysis of organic matter in such sediments is Rock Eval pyrolysis. In small lakes, however, routine interpretation of Rock Eval data can be misleading. Lack of tributaries capable of transporting larger woody fragments into small lakes causes a bias towards the input of lipid-rich leaf waxes and cuticles. This hydrogen-rich and oxygen-depleted terrigenous organic matter (HI = 250 -600 [mg HC/g TOC] and OI = 20 -40 [mg CO 2 /g TOC]) can easily be misinterpreted as being of algal origin. Differentiation of terrigenous plantderived hydrogen-rich organic matter from algal organic matter is readily achieved by including C/N-elemental ratios and lipid biomarker data.