115-3 Mapping Plume Margins as a New Continental‐Scale Tectono‐Stratigraphic Feature

Session: Petrology, Volcanology, and Mantle Plumes across the Solar System (Posters)

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Abstract:

Mantle plumes shape continents far beyond their volcanic centers. While most studies focus on the central uplift above a rising plume head, surrounding regions also record deformation, erosion, and stratigraphic changes. These regions have not been formally defined or systematically mapped, limiting their integration into continental‐scale reconstructions.

I define the plume margin—in analogy to a plate margin—as the arcuate to annular belt marking the outer limit of deformation during the two‐phase evolution of a rising and dissipating plume head. It is not part of the plume itself, but records the tectono‐stratigraphic imprint of plume–plate interaction in the overlying lithosphere, expressed through patterns of deformation, erosion, and sequences on continental‐scale geological maps.

Plume margins are identified on geological maps or chronostratigraphic charts by mapping events postulated from theory and linking evidence across adjacent stratigraphic columns. Their record includes a characteristic hiatus pattern (Friedrich, 2019, Geological Magazine) and regional‐scale unconformities (Friedrich et al., 2018, Gondwana Research), in particular a diagnostic double‐unconformity‐bounded sequence defining plume‐margin stratigraphy.

In the first phase, ascent of the plume head through the mantle deforms both the center and surrounding margin, producing domal uplift, erosion, radial drainage, giant dike swarms, narrow grabens, and flood basalts. The margin initially behaves like the center, recording early uplift and erosion as it expands inward toward the dome. In the second phase, buoyant plume material spreads laterally beneath the lithosphere. This flow drives dynamic topography, causing renewed uplift, erosion, and drainage reorganization in the margin. Sediments deposited earlier may be partly or fully removed, depending on sediment routing, climate, and other tectonic influences.This two‐phase evolution leaves a distinct geological record—petrological, sedimentological, geomorphological, and structural—organized into three related stratigraphic columns: center, margin, and distal. Recognizing this architecture restores the spatial dimension to chronostratigraphic frameworks and calls for continental‐scale maps with stage‐level resolution in plume‐affected regions.

Plume‐margin mapping is illustrated with the Iceland and Columbia River–Yellowstone systems, linking stratigraphic records across continents and testing geodynamic models. However, most continental maps remain at series resolution, underscoring the need for coordinated international efforts to produce the next generation of high‐resolution maps. Defining and mapping plume margins offers a powerful framework for reconstructing continental evolution and evaluating the interplay of plate and plume tectonics through deep time.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11304

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