Incipient mantle plume evolution: Constraints from ancient landscapes buried beneath the North Sea

Abstract

Geological observations that constrain the history of mantle convection are sparse despite its importance in determining vertical and horizontal plate motions, plate rheology, and magmatism. We use a suite of geological and geophysical observations from the northern North Sea to constrain evolution of the incipient Paleocene-Eocene Icelandic plume. Well data and a three-dimensional seismic survey are used to reconstruct a 58-55 Ma landscape now buried 1.5 km beneath the seabed in the Bressay region. Geochemical analyses of cuttings from wells that intersect the landscape indicate the presence of angiosperm debris. These observations, combined with presence of coarse clastic material, interpreted beach ridges, and a large dendritic drainage network, indicate that this landscape formed subaerially. Longitudinal profiles of paleo-rivers were extracted and inverted for an uplift rate history, indicating three distinct phases of uplift and total cumulative uplift of 350 m. Dinoflagellate cysts in the surrounding marine stratigraphy indicate that this terrestrial landscape formed in <3 Ma and was rapidly drowned. This uplift history is similar to that of a slightly older buried landscape in the Faeroe-Shetland basin 400 km to the west. These records of vertical motion are consistent with pulses of anomalously hot asthenosphere spreading out from the incipient Icelandic plume. Using simple isostatic calculations, we estimate that the maximum thermal anomaly beneath Bressay was 50-1008C. Our observations suggest that a thermal anomaly departed the Icelandic plume around 57.4 6 2.2 Ma at the latest and travelled with a velocity > 150 km/Ma.

Manifestation of Tectonic and Climatic Perturbations in Deep-Time Stratigraphy – An Example From the Paleocene Succession Offshore Western Norway

“…These values are comparable to the predicted amplitude of dynamic uplift of ∼0.5 km at 60 ± 5 Ma from Barnett-Moore et al (2017). If we further assume that the estimated basin-averaged denudation rates of 60-250 m/Myr reflect uplift rate, these are also similar, but on the low side of the uplift rates estimated for the northern British Isles (e.g., Shaw Champion et al, 2008;Stucky de Quay et al, 2017).…”

“…Our favored model is that regional uplift was driven by the arrival of the Iceland mantle plume as modeled by Barnett-Moore et al (2017). But in contrast to previous studies from the British Isles (Shaw Champion et al, 2008;Hartley et al, 2011;Stucky de Quay et al, 2017), which focus on the last ∼3 Myr FIGURE 10 | Plot showing calculated sediment supply and estimated paleotopography from this study together with predicted dynamic topography (uncertainty range ± 5 Myr) and magmatic intensity in the North Atlantic Igneous Province. Also shown is the estimated PETM sediment supply from this study.…”

Causes and Consequences of Diachronous V‐Shaped Ridges in the North Atlantic Ocean

“…Along the fringing margins of the North Atlantic Ocean, a series of erosional surfaces were carved into postrift marine strata. In the Faroe‐Shetland and North Sea basins, these buried ephemeral landscapes have been mapped on three‐dimensional seismic reflection surveys (Shaw Champion et al, ; Hartley et al, ; Rudge et al, ; Smallwood & White, ; Stucky de Quay et al, ). Subaerial exposure generally lasted less than 0.5 Ma, and landscape unconformities are both underlain and buried by marine sedimentary rocks.…”

Prolonged dynamic support from the Icelandic plume of the NE Atlantic margin

“…As noted, ~0.5 -1 km of subsidence throughout the Late Palaeocene and Early Eocene (marked by retreat of the palaeocoastline), and therefore eustasy cannot account for the scale and rapidity of the subsidence observed in the Faroe-Shetland Basin. Additionally, the magnitude of uplift and subsidence observed within the Faroe-Shetland Basin is localised, as uplift of a similar age on the East Shetland Platform (300 km east of the study area) is of a lesser extent, with much less incision of the Palaeolandscape at peak uplift (Underhill, 2001;Stucky de Quay et al, 2017). As eustatic changes in sea level are global, they cannot account for the uplift and subsidence observed across the Faroe-Shetland Basin and East Shetland Platform…”

“…At ~63 Ma, uplift of the north east Atlantic commenced (White & Mckenzie, 1989;Brodie & White, 1994;Nadin & Kusznir, 1995). The effects of this uplift are observed throughout large parts of Northwest Europe, from Greenland to the North Sea (Bertram & Milton, 1989;Jones & Milton, 1994;Nadin & Kusznir, 1995;Clift & Turner, 1998;Dam et al, 1998;Stucky de Quay et al, 2017). In the Faroe-Shetland Basin, located offshore Northwest Scotland (Fig.…”