On seismic sections we found by level tracing and fossil correlating among some wells that the bottom boundary of the fossil assemblage zone is correlated with the seismic marker T4 so a seismic sequence boundary ( chronohorizon ) is recognized .

在地震时间剖面上，通过井间追层及化石对比，发现这一化石组合 带底界均与 T4地震标准层相对应，形成了一个地震层序界面（等时界面）。

Silver metal remained in the metal consumption zone acting especially as an inert marker except for a few particles which were incorporated into the growing scales .

合金氧化时Ag以金属态留下，在金属Cu的消耗 带中自然地成为惰性 标记。