Microbathymetry data, in situ observations, and sampling along the 13°20′N and 13°20′N oceanic core complexes (OCCs) reveal mechanisms of detachment fault denudation at the seafloor, links between tectonic extension and mass wasting, and expose the nature of corrugations, ubiquitous at OCCs. In the initial stages of detachment faulting and high‐angle fault, scarps show extensive mass wasting that reduces their slope. Flexural rotation further lowers scarp slope, hinders mass wasting, resulting in morphologically complex chaotic terrain between the breakaway and the denuded corrugated surface. Extension and drag along the fault plane uplifts a wedge of hangingwall material (apron). The detachment surface emerges along a continuous moat that sheds rocks and covers it with unconsolidated rubble, while local slumping emplaces rubble ridges overlying corrugations. The detachment fault zone is a set of anostomosed slip planes, elongated in the along‐extension direction. Slip planes bind fault rock bodies defining the corrugations observed in microbathymetry and sonar. Fault planes with extension‐parallel stria are exposed along corrugation flanks, where the rubble cover is shed. Detachment fault rocks are primarily basalt fault breccia at 13°20′N OCC, and gabbro and peridotite at 13°30′N, demonstrating that brittle strain localization in shallow lithosphere form corrugations, regardless of lithologies in the detachment zone. Finally, faulting and volcanism dismember the 13°30′N OCC, with widespread present and past hydrothermal activity (Semenov fields), while the Irinovskoe hydrothermal field at the 13°20′N core complex suggests a magmatic source within the footwall. These results confirm the ubiquitous relationship between hydrothermal activity and oceanic detachment formation and evolution.

Rapid sea-level rise caused by the collapse of large ice sheets is a global threat to human societies 1 . In the last deglacial period, the rate of global sea-level rise peaked at more than 4 cm/yr during Meltwater Pulse 1a, which coincided with the abrupt Bølling warming event ~14,650 yr ago 2-5 . However, the sources of the meltwater have proven elusive 6,7 , and the contribution from Eurasian ice sheets has until now been considered negligible [8][9][10] . Here we show that marine-based sectors of the Eurasian ice sheet complex collapsed at the Bølling transition and lost an ice volume of between 4.5 and 7.9 m sea level equivalents (95% quantiles) over 500 yr. During peak melting 14,650 -14,310 yr ago, Eurasian ice sheets lost between 3.3 and 6.7 m sea level equivalents (95% quantiles), thus contributing significantly to Meltwater Pulse 1a. A mean meltwater flux of 0.2 Sv over 300 yr was injected into the Norwegian Sea and the Arctic Ocean during a time when proxy evidence suggests vigorous Atlantic meridional overturning circulation 11,12 . Our reconstruction of the EIS deglaciation shows that a marine-based ice sheet comparable in size to the West Antarctic ice sheet can collapse in as little as 300-500 years.Understanding the response of marine-based ice sheets to global warming is critical to future sea-level projections 1 . Today large marine-based ice sheets are situated in the Antarctic, with the West Antarctic ice sheet long considered to be particularly vulnerable [13][14][15][16] . The time scale and magnitude of its potential disintegration are highly uncertain, however, and its projected contribution to sea-level rise over the next centuries varies by orders of magnitude 17,18 . To add further empirical constraints, researchers turn to past deglaciation events to study the tempo and mode of ice sheet collapse in a warming world. The West

Common species shape the world around us, and changes in their commonness signify large-scale shifts in ecosystem structure and function. However, our understanding of long-term ecosystem response to environmental forcing in the deep past is centred on species richness, neglecting the disproportional impact of common species. Here, we use common and widespread species of planktonic foraminifera in deep-sea sediments to track changes in observed global occupancy (proportion of sampled sites at which a species is present and observed) through the turbulent climatic history of the last 65 Myr. Our approach is sensitive to relative changes in global abundance of the species set and robust to factors that bias richness estimators. Using three independent methods for detecting causality, we show that the observed global occupancy of planktonic foraminifera has been dynamically coupled to past oceanographic changes captured in deep-ocean temperature reconstructions. The causal inference does not imply a direct mechanism, but is consistent with an indirect, time-delayed causal linkage. Given the strong quantitative evidence that a dynamical coupling exists, we hypothesize that mixotrophy (symbiont hosting) may be an ecological factor linking the global abundance of planktonic foraminifera to long-term climate changes via the relative extent of oligotrophic oceans.