抄録
The validity of some maturity parameters based on alkylated phenanthrenes composition was examined for extracts from the Miocene source rocks in the Niigata Basin, central Japan. The source rock of Nanatani and Teradomari Formations in the Niigata Basin are characterized by the relatively high heating rate. Maturity parameters, such as Methylphenanthrene Ratio (MPR), Methylphenanthrene Index-3 (MPI3) and Dimethylphenanthrene Ratio (DPR), based only on methylphenanthrene or dimethylphenanthrene isomers have the similar evolutional trends against vitrinite reflectance (Ro%), and are useful at the maturity level from 1.0 to 1.7 %Ro. The relationship between Ro% and these parameters is not dependent on the geologic age of the source rock. Whereas, Methylphenanthrene Index-1 (MPI1) has a different trend, because it includes phenanthrene in its formula and the relationship between Ro% and MPI1 is possibly related to the heating rate.
