Dominant eccentricity cycles in paleoenvironmental variabilities recorded by pelagic sediments in the western Pacific during 15–11 Ma

The middle Miocene Climate Transition (MMCT) was a major event that resulted in a global cooling, providing valuable insights into the transition from global warming to cooling. In this study, we analyze a well-dated sediment core, GC18, to establish potential linkages between sedimentary processes in the western Pacific and global climate changes during the MMCT. The main findings are as follows: (1) Integrating authigenic 10Be/9Be dating, magnetostratigraphy, and astronomical tuning, we determined that core GC18 predominantly deposited during ~11–15 Ma, with a sedimentation rate of 0.5–2 mm/kyr; (2) Chemical scanning identified ten elements, including Al, Si, P, Ca, Sr, Mn, Fe, Ti, Ni, and Ba, which can be clustered into four groups; (3) These four groups serve as proxies for eolian dust (Al and Si), biogenic debris (P, Ca, and Sr), deep-sea redox changes (Mn, Fe, Ti, and Ni), and marine productivity (Ba). Based on these results, we find that all four processes were influenced by eccentricity cycles, indicating the dominant role of orbital forcing during the MMCT. Overall, sedimentary archives in the western Pacific offer valuable evidence of the various climatic processes during the middle Miocene and warrant further investigations.