Two deep-mantle sources for Paleocene doming and volcanism in the North Atlantic

The North Atlantic Igneous Province (NAIP) erupted in two major pulses that coincide with the continental breakup and the opening of the North Atlantic Ocean over a period from 62 to 54 Ma. The unknown mantle structure under the North Atlantic during the Paleocene represents a major missing link in deciphering the geodynamic causes of this event. To address this outstanding challenge, we use a back-and-forth iterative method for time-reversed global convection modeling over the Cenozoic Era which incorporates models of present-day tomography-based mantle heterogeneity. We find that the Paleocene mantle under the North Atlantic is characterized by two major low-density plumes in the lower mantle: one beneath Greenland and another beneath the Azores. These strong lower-mantle upwellings generate small-scale hot upwellings and cold downwellings in the upper mantle. The upwellings are dispersed sources of magmatism and topographic uplift that were active on the rifted margins of the North Atlantic during the formation of the NAIP. While most studies of the Paleocene evolution of the North Atlantic have focused on the proto-Icelandic plume, our Cenozoic reconstructions reveal the equally important dynamics of a hot, buoyant, mantle-wide upwelling below the Azores.

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Ambient seismic noise imaging of the lowermost mantle beneath the North Atlantic Ocean

Geophysical Journal International ◽

10.1093/gji/ggaa210 ◽

2020 ◽

Vol 222 (2) ◽

pp. 1339-1351 ◽

Cited By ~ 3

Author(s):

Lise Retailleau ◽

Pierre Boué ◽

Lei Li ◽

Michel Campillo

Keyword(s):

North Atlantic ◽

Lower Mantle ◽

North Atlantic Ocean ◽

Synthetic Data ◽

Body Waves ◽

P Wave ◽

Eastern United States ◽

The North ◽

Seismic Records ◽

The North Atlantic

SUMMARY Body waves can be extracted from correlation functions computed from seismic records even at teleseismic distances. Here we use P and PcP waves from the secondary microseism frequency band that are propagating between Europe and the Eastern United States to image the core–mantle boundary (CMB) and D” structure beneath the North Atlantic. This study presents the first 3-D image of the lower mantle obtained from ocean-generated microseism data. Robustness of our results is evaluated by comparing images produced by propagation in both directions. Our observations reveal complex patterns of lateral and vertical variations of P-wave reflectivity with a particularly strong anomaly extending upward in the lower mantle up to 2600 km deep. We compare these results with synthetic data and associate this anomaly to a Vp velocity increase above the CMB. Our image aims at promoting the study of the lower mantle with microseism noise excitations.

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Transition to Widowhood Among Older Adults in Rural Areas: A Study From the Faroe Islands

OMEGA - Journal of Death and Dying ◽

10.1177/00302228211024119 ◽

2021 ◽

pp. 003022282110241

Author(s):

Elsa J. D. Johannesen ◽

Ása Róin

Keyword(s):

North Atlantic ◽

Rural Areas ◽

Daily Living ◽

North Atlantic Ocean ◽

Small Scale ◽

Analytic Method ◽

Faroe Islands ◽

The North ◽

Individual Support ◽

The North Atlantic

Studies have shown that losing a spouse can cause both physical and mental suffering for the bereaved. This qualitative study aimed to gather knowledge about how men and women in the Faroe Islands, a small-scale society in the North Atlantic Ocean, managed the transition to widowhood. Five women and three men were interviewed, their age varying from 67 to 74 years. A hermeneutic analytic method was applied. Our findings showed that managing the transition to widowhood followed two tracks, namely the process of loss and the process of restoration. For participants locked in either process, the transition caused severe disruption in daily living, while participants who managed to oscillate between the two processes appeared to manage the transition to widowhood and get on with their lives. Our findings, and those from other studies, point to the need to offer structured individual support for people who have lost their life partner.

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Trace element and isotope constraints on crustal anatexis by upwelling mantle melts in the North Atlantic Igneous Province: an example from the Isle of Rum, NW Scotland

Geological Magazine ◽

10.1017/s0016756809006244 ◽

2009 ◽

Vol 146 (3) ◽

pp. 382-399 ◽

Cited By ~ 24

Author(s):

ROMAIN MEYER ◽

GRAEME R. NICOLL ◽

JAN HERTOGEN ◽

VALENTIN R. TROLL ◽

ROBERT M. ELLAM ◽

...

Keyword(s):

Trace Element ◽

North Atlantic ◽

Trace Element Content ◽

Crustal Anatexis ◽

The North ◽

Rock Types ◽

Rifted Margins ◽

Igneous Province ◽

The North Atlantic ◽

North Atlantic Igneous Province

AbstractSr and Nd isotope ratios, together with lithophile trace elements, have been measured in a representative set of igneous rocks and Lewisian gneisses from the Isle of Rum in order to unravel the petrogenesis of the felsic rocks that erupted in the early stages of Palaeogene magmatism in the North Atlantic Igneous Province (NAIP). The Rum rhyodacites appear to be the products of large amounts of melting of Lewisian amphibolite gneiss. The Sr and Nd isotopic composition of the magmas can be explained without invoking an additional granulitic crustal component. Concentrations of the trace element Cs in the rhyodacites strongly suggests that the gneiss parent rock had experienced Cs and Rb loss prior to Palaeogene times, possibly during a Caledonian event. This depletion caused heterogeneity with respect to87Sr/86Sr in the crustal source of silicic melts. Other igneous rock types on Rum (dacites, early gabbros) are mixtures of crustal melts and and primary mantle melts. Forward Rare Earth Element modelling shows that late stage picritic melts on Rum are close analogues for the parent melts of the Rum Layered Suite, and for the mantle melts that caused crustal anatexis of the Lewisian gneiss. These primary mantle melts have close affinities to Mid-Oceanic Ridge Basalts (MORB), whose trace element content varies from slightly depleted to slightly enriched. Crustal anatexis is a common process in the rift-to-drift evolution during continental break-up and the formation of Volcanic Rifted Margins systems. The ‘early felsic–later mafic’ volcanic rock associations from Rum are compared to similar associations recovered from the now-drowned seaward-dipping wedges on the shelf of SE Greenland and on the Vøring Plateau (Norwegian Sea). These three regions show geochemical differences that result from variations in the regional crustal composition and the depth at which crustal anatexis took place.

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