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中新世可以说是东北太平洋发生“深刻变化”的地史时期，许多古海洋事件发生在这一时期。取自该区４个柱状样研究结果发现，研究区（７°～１０°Ｎ，１４０°～１５０°Ｗ）仅发育下中新统地层，中中新统只有零星分布。除１个柱状样外，其余３个均为下中新统直接与上上新统或第四系相接触。在中新世，研究区ＣＣＤ出现多次波动，古水深变化幅度达５００ｍ。受南极底层流的强烈影响，出现多次间断时间长短不一的沉积间断和ＣａＣＯ３含量出现旋回性变化。古气候出现９次冷暖交替变化，海平面受其影响而出现频繁波动。此外，该区在中新世期间生物生产力与沉积速率出现较大变化。由于该区在中新世出现上述这些特定沉积环境与事件，形成一个对多金属结核生长特别有利的环境，从而成为分布广泛的现代大洋底多金属结核的主要生长期。
The Miocene can be said to be a “profound change” in the northeastern Pacific Ocean. Many ancient marine events occurred during this period. Based on the four columnar samples from this area, it was found that only the Lower Miocene strata were developed in the study area (7 ° ~ 10 ° N, 140 ° ~150 ° W), while the Miocene only had sporadic distribution. Except for 1 columnar sample, the remaining 3 are all the Lower Miocene in direct contact with the Upper Paleocene or Quaternary. In the Miocene, the CCD in the study area fluctuated many times, and the paleo-water depth changed by 500m. Due to the strong influence of the bottom flow in the Antarctic, there are many discontinuities in sedimentary intervals and cyclic changes in CaCO3 content. Paleoclimate alternates between warm and cold nine times, and sea level fluctuates frequently due to its influence. In addition, there was a great change in the productivity and sedimentation rate of the biosphere during the Miocene. As these specific depositional environments and events described above emerge in the area during the Miocene, the area formed a particularly favorable environment for the growth of polymetallic nodules and became the main growing season for the widely distributed modern ocean floor polymetallic nodules.