[BPT04-P09] Boundary of Sakamotozawa formation, Nagaiwa formation and Kanokura formation in a part of Hikoroiti district
Keywords:limestone, Sakamotozawa formation, Nagaiwa formation, Kanokura formation, Ofunato
Sakamotozawa formation is in contact with clino-unconformity of Nagaiwa formation(Mid Carboniferous) and conformity of Kanokura formation(Middle Permian).
In this research, to add a new interpretation to the previous research, we decided more accurate boundary of Nagaiwa, Sakamotozawa and Kanokura formation, and conducted a survey.
As a result, the sandstones in some areas considered to be Nagaiwa and Kanokura formation showed the very similar Ti-Nb ratio to sandstones of Sakamotozawa formation.
In addition, we measured undissolved residue of the muddy limestone from Sakamotozawa formation then it was identified that the amount of Cr·Ni contained in samples are particularly rich rather than the general sandstones of Sakamotozawa formation.
This suggests that there was a provenance which abundant Cr-Ni existed like serpentintite during sedimentation of limestone.