Quantifying transient mantle convective uplift: An example from the Faroe‐Shetland basin

Abstract

The Icelandic mantle plume generated maximum uplift in early Paleogene times. The Faroe‐Shetland basin, which fringes the North Atlantic margin of Europe, was close to the center of early Paleogene Icelandic plume activity. Three‐dimensional seismic reflection data from the Faroe‐Shetland basin reveal sedimentary geometries that allow a phase of transient uplift to be accurately reconstructed and quantified. Close to the Paleocene/Eocene boundary (circa 56 Ma), rapid uplift resulted in fluvial incision into marine sediments. This unconformity was buried by nonmarine sediments, recording the decay of transient uplift. Relief on the unconformity was ∼550 m, constraining the minimum amount of surface uplift. Some 60 m of this uplift can be attributed to the isostatic response to erosional unloading. Tectonic uplift of over 490 m peaked and decayed within 3 Ma. Rates of water‐loaded tectonic subsidence following peak uplift are several times greater than maximum expected postrift subsidence rates. The amplitude and duration of this transient effect is best explained by a mantle convective phenomenon. We suggest that a region of hot plume material flowed laterally beneath the lithosphere, producing transient uplift which decayed when plume material was advected farther away. Our analysis suggests that under certain circumstances, stratigraphic records can yield valuable quantitative information about aspects of mantle convective circulation.