STRATIGRAPHIC FRAMEWORK FOR THE PLUME MODE OF MANTLE CONVECTION

Mantle convection is a fundamental planetary process. Its plate mode is well established and expressed by plate tectonics; its plume mode is equally well established and expressed by interregional-scale geological patterns; I developed a stratigraphic framework to translate the surface effects predicted by the plume mode, which also serves as a methodology to analyze continent-scale geological maps based on unconformities and hiatuses. The surface expression of ascending plumes lasts for tens of millions of years and leaves a distinct record, not only as a > 1-km-high dome above the plume center, but also above the plume head margins and in distal regions (> 1200 km). Regional-scale erosion of the uplifting dome dominates prior to arrival of the plume head at the base of the lithosphere, and is followed by extensional collapse and flood-basalt eruption. A nearly complete sedimentary record may be preserved in distal regions, which did not experience any plume-related uplift. The marginal section of the uplifted dome is the most complex, because it undergoes multiple episodes of uplift and erosion followed by subsidence and sedimentation, and renewed outward-directed uplift and erosion as the plume head collapses and spreads laterally. Thus, marginal regions contain regional-scale “double-unconformity-bounded” stratigraphic successions. Complete global stratigraphic synthesis of plate interiors requires integration of plate- and plume-stratigraphic frameworks. This plume-stratigraphic framework is event-based, interregional, but not global, with time-dependent amplitudes that are significantly larger than global eustatic sea-level fluctuations.