本邦石灰岩中の炭化水素ガスおよび有機態,元素態炭素含有量

抄録

As a part of the geochemical studies of limestone, C₁-C₅ hydrocarbons, organic and elementary carbons in the carbonate rocks of various ages from Quaternary to Silurian were determined. To determine the various forms of carbon were used the acid insoluble residues.
Organic carbon was determined by combustion in the elementary analyser at 300°C for 60 minutes, and total residual carbon was determined by CHN corder. Elementary carbon can be obtained as the difference between total residual carbon and organic one, and it consists mainly of amorphous carbon. In Quaternary (Kikai-jima), Tertiary (Sagara) and Jurassic (Sagawa and Sohma, so-called “Torinosu” limestone), methane, ethane, propane, butane and in some case pentane were found, on the contrary, in the limestone of Carboniferous and older geologic ages methane was the only hydrocarbon detected.
Much larger amounts of C₁-C₅ hydrocarbons were measured in the Torinosu limestone, for example, specimen No. 7 contains 104ml per kilogram of limestone. Most of others contain below 10ml per kilogram.
The results for the middle permian dolomite sample from Kuzuu show a strong resemblance to the Torinosu limestone.
The values of C₁/C₂-C₅ ratio generally tend to increase with increasing age of carbonate rocks.
There is a negative correlation between the amounts of C₁-C₅ hydrocarbons and ele. C/org. C ratios.