In the earth history, a geologist can explore the historical destruction of forest by observing the n-alkane distribution from the rock studied.
N-alkane is the most important and reliable proxy for the identification of the terrestrial plant collapse. Because normal n– alkane like nC14- nC35 or more deposited in the sediment after degradation plant leaf. Land plant collapse can be identified based on the number of carbon found in the rock sample studied. The GCMS chromatogram can show a number of carbon (C). Normal n-alkane in the rock sample can be derived from resources.
Sources of n- alkane:
- Marine algae;
- Land plant;
- Marine algae are the sources of short-chain n alkane. All the carbon number ranging from c14 to c-19 has come from Marine Algae. Because the algae do not contain any cellulose, hence after the degradation all the carbon will you be short in number?
- Moss is the source of the n-C20 to n-C26. These carbon ranges found in the rocks can explain the Paleoenvironment in between Marine and land. Moss, fern are the sources of these carbon number.
- The plant contains cellulose hence carbon number higher than n-C26 will indicate the collapse of the plant.
Sedimentary rocks contain too many complex mixtures of the geochemical biomarker. This biomarker explains the paleoenvironment. The biomarker is the very important study to explain the history of the earth if it does not have any bone or bony fossil evidence.
How does normal n- alkane can be identified?
Geologist uses a GCMSMS (gas chromatogram mass spectrometry-mass spectrometry) analyzer to identify all the molecules from the extracted rock sample solution. In the GCmsms, the mass fragment ion for the n– alkane is m/z 57. All the n-alkane graph will appear as chromatogram of n- alkane. Then we can identify based on the molecular weight of the specific number of an alkane. All the peak of the alkane is very distinct to identify.