Prior to ~1 million years ago (Ma), variations in global ice volume were dominated by changes in obliquity; however, the role of precession remains unresolved. Using a record of North Atlantic ice rafting spanning the past 1.7 million years, we find that the onset of ice rafting within a given glacial cycle (reflecting ice sheet expansion) consistently occurred during times of decreasing obliquity whereas mass ice wasting (ablation) events were consistently tied to minima in precession. Furthermore, our results suggest that the ubiquitous association between precession-driven mass wasting events and glacial termination is a distinct feature of the mid to late Pleistocene. Before then (increasing), obliquity alone was sufficient to end a glacial cycle, before losing its dominant grip on deglaciation with the southward extension of Northern Hemisphere ice sheets since ~1 Ma.

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In late 2016, the IODP Expedition 366 drilled 21 holes on summits and flanks of three serpentinite mud volcanoes (SMVs) of the Mariana Forearc: Yinazao (Blue Moon), Fantangisña (Celestial), and Asùt Tesoru (Big Blue). The drilling reached the forearc sediments underneath the SMVs only at Site U1498 where, according to data from this study, the biostratigraphic age of Fantangisña appears to be well constrained, with a pelagic cover on top of the serpentine mud flows of 0.44 Ma and an age of the forearc sediments of 11.21 Ma. With an estimated age of at least 10.77 Myr this is, to our knowledge, the oldest mud volcano ever dated. To link the age of the edifice with its eruptive dynamics, we performed rheological tests of natural samples of serpentine mud from the Fantangisña SMV for the first time. These experiments not only confirm the highly viscous characteristic of the mud breccia but also identify different muds' mineralogical compositions (i.e., serpentine-rich vs. serpentine-poor sediments) and water contents as being responsible for the main rheological variations. The viscosity from the rheological data, together with the physical properties of the mud breccia and the clasts measured onboard IODP366, under several assumptions, allow us to estimate of flow velocities and a depth of the mud source at ∼8.4 km below seafloor. Moreover, comparison of erupted mud breccia volumes from bathymetry, seismic data, and calculations shows how the SMV evolution is linked to episodic events, highlighting that Fantangisña has actively been expelling sediments during 2.41% of its life span.

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