Interaction of Gravity Flows With a Rugged Mid-Ocean-Ridge Seafloor: An Outcrop Example from Macquarie Island

Rugged bathymetry along slow-spreading mid-ocean ridges significantly influences gravity flows derived from oceanic fault scarps, as demonstrated by sedimentary lithofacies variations on Macquarie Island. The study reveals that pillow-basalt terranes funnel gravity flows into confined bedrock corridors, leading to systematic vertical and lateral changes in sediment deposition. Initial stages of corridor filling suppress flow dilution due to tight confinement, while later stages promote more dilute flows with lateral gradations from coarse-grained axial turbidites to thinly interbedded overbank facies. Partly confined tabular-basalt-floored basins show lateral expansion and dilution of gravity flows, recording multiple reflections off fault barriers and preserving coarsening-upward trends indicative of sediment-starved submarine fans.

Portner, R. A., Dickinson, J. A., & Daczko, N. R. (2011). Interaction of Gravity Flows With a Rugged Mid-Ocean-Ridge Seafloor: An Outcrop Example from Macquarie Island. Journal of Sedimentary Research, 81(5), 355–375. https://doi.org/10.2110/jsr.2011.30