Paleomagnetic data as a test of correlations of the Pliocene Wakebe tephra in the Tokai Group, central Japan

抄録

This paper presents a paleomagnetic test for the correlation of tephra over large areas. A recent preliminary investigation suggests the possibility, based mainly on geochemical data, that the Pliocene Wakebe tephra in the lower Kameyama Formation of the Tokai Group is correlative with a widespread tephra in central Japan that was deposited in a normal polarity subchron of the Gauss Chron (C2An). Here, new paleomagnetic data are presented to show that reverse polarity remanent magnetizations are recorded in the Wakebe tephra and in siltstones located immediately above and below the tephra. The results do not support the preliminary correlation of the Wakebe tephra with the widespread tephra of normal polarity, and correlation with this tephra needs to be reconsidered. The Wakebe tephra was deposited between ~3.95 Ma (age of the underlying Akogi tephra) and 3.596 Ma (Gauss-Gilbert boundary age) in the late Gilbert Chron (C2Ar).