Moretane and Hopane ratio might be a an important proxy to identify the huge soil input from land to sea

The world so far experienced 5 biggest mass extinction. The Permian Triassic mass extinction is one of them. It happened 252 Million years ago. The people think marine extinction and the terrestrial extinction happened together. But the recent finding says, there is no terrestrial extinction happened in the Permian Triassic boundary.

Scientists can identify terrestrial devastation based on biomarker research. C30 Moretane and hopane isomeres are one the well-accepted biomarker to identify the excess soil input from the land to the sea caused by the plants’ devastation.

What is moretane?

βα-Moretane and αβ-hopane are the isomers of the C30-hopane. The hopane has the four isomers named ββ hopane, αβ hopane, βα-hopane, and αα- hopane. Among these hopane isomers, the αβ and the βα-hopane ( called Moretane)  are the most thermodynamically stable. Because, during diagenesis and the catechesis of the sedimentary organic matter, the ββ hopane isomers converted to the more stable αβ hopane or βα hopane. βα hopane is less stable than αβ hopane. So, this overall processes of the conversion of the ββ > βα > αβ hopane are important to apply to the organic geochemical research. The general trends to the formation of the ββ to the αβ hopane are 1:20. But if in the sedimentary organic matter shows higher than this ratio then geologist must think differently. The high moretane/hopane ratio can only be found if there is a high input of the plant to the terrestrial soil.

How to identify the Moretane?

The meretane and Hopane can be identified in the Lab using the GCMS mass hunter technology. The mass fragment of the C30 hopane isomers is M/Z 426.6- 191.3 in the multiple reaction monitoring methods (MRM).

 

 

 

Hopane
C30 Hopane isomers

 

There are some other hypotheses for the increased ratio of the Moretane/ Hopane. Diagenetic effects of the organic matter and the influence of the clay minerals can have a role to produce more moretane isomers than the hopane.  Acidification of the soil causes the high hopane ratio can be found in the sedimentary rocks.  This type of hopene is called the coal type hopane.

Excess terrestrial soil input from the land to the sea caused by the devastation of the land plants can be identified using the high ratio of the Moretane/Hopane.

Sources;https://www.sciencedirect.com/science/article

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