scholarly journals 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

2009 ◽  
Vol 146 (3) ◽  
pp. 382-399 ◽  
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.

Enhanced volcanism associated to the emplacement of the North Atlantic Igneous Province during the PETM evidenced by mercury anomalies in Pyrenean foreland sections

2021 ◽  
Author(s):  
Maxime Tremblin ◽  
Hassan Khozyem ◽  
Jorge E. Spangenberg ◽  
Charlotte Fillon ◽  
Sylvain Calassou ◽  
...  
Keyword(s):  
North Atlantic ◽  
External Perturbation ◽  
The North ◽  
Sequence Of Events ◽  
Source To Sink ◽  
Large Perturbation ◽  
Igneous Province ◽  
Multiple Pulses ◽  
The North Atlantic ◽  
North Atlantic Igneous Province

<p>The Paleocene-Eocene thermal maximum (PETM; ~55.6 Ma) is one of the most pronounced and the best known of the transient hyperthermal events of the Paleogene. The PETM is characterized by global warming, a significant perturbation of the carbon cycle, and a large perturbation of the biosphere. This extraordinary event is recorded by sharp negative carbon excursions (NCIE) in both oceanic and terrestrial carbonates. The sequence of events triggering this disturbance and the source of the <sup>13</sup>C-depleted carbon for the NCIE remains controversial. External perturbation such as volcanism, associated with the setup of the North Atlantic Igneous Province (NAIP), is suspected to be one of the mechanisms responsible for this abrupt climate upheaval. One proxy for investigating the possible link between the establishment of the NAIP and perturbation associated with the PETM is to study mercury (Hg) concentrations record in marine and continental sedimentary successions.</p><p>In this study, we present new high-resolution mercury and stable isotopic records from peripheral basins of the Pyrenean orogen across the PETM. The four studies sections vary from continental to bathyal deposit environment and offer the potential to evaluate how major climatic disturbances are associated with the PETM record through a continental to marine transect.</p><p>The data obtained reveal the occurrence of two main NCIEs. Based on biostratigraphy and similarity of shape and amplitude of the isotopic excursions with global records, the largest NCIE is interpreted as the PETM. This sharp excursion is preceded by another one that we interpreted as the Pre-Onset Excursion (POE), founded in some other profiles worldwide. These two NCIEs are systematically associated with important mercury anomalies, whatever the environment considered. Increase in Hg contents shows no correlation with clay or total organic carbon contents, suggesting that the influences of local processes or Hg scavenging by organic matter appear to be insignificant. These results show that multiple pulses of volcanism, probably associated with the emplacement of the NAIP, contributed to the onset and the long duration of the PETM. In addition, our study highlights the possibility to get reliable information about past extreme climate events from sedimentary successions even if deposited within active tectonic domains.</p><p>This work is financed and carried out within the framework of the BRGM-TOTAL Source-to-Sink project.</p>

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

2019 ◽  
Vol 116 (27) ◽  
pp. 13227-13232 ◽  
Author(s):  
Petar Glišović ◽  
Alessandro M. Forte
Keyword(s):  
North Atlantic ◽  
Lower Mantle ◽  
North Atlantic Ocean ◽  
Small Scale ◽  
The North ◽  
Rifted Margins ◽  
Mantle Sources ◽  
Cenozoic Era ◽  
The North Atlantic ◽  
North Atlantic Igneous Province

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.

scholarly journals The onset of the North Atlantic Igneous Province in a rifting perspective

2009 ◽  
Vol 146 (3) ◽  
pp. 309-325 ◽  
Author(s):  
J. HANSEN ◽  
D. A. JERRAM ◽  
K. McCAFFREY ◽  
S. R. PASSEY
Keyword(s):  
North Atlantic ◽  
Regional Scale ◽  
The North ◽  
Time Space ◽  
Lithospheric Extension ◽  
Igneous Province ◽  
The North Atlantic ◽  
North Atlantic Igneous Province ◽  
North Atlantic Area ◽  
Atlantic Area

AbstractThe processes that led to the onset and evolution of the North Atlantic Igneous Province (NAIP) have been a theme of debate in the past decades. A popular theory has been that the impingement on the lower lithosphere of a hot mantle plume (the ‘Ancestral Iceland’ plume) initiated the first voluminous outbursts of lava and initiated rifting in the North Atlantic area in Early Palaeogene times. Here we review previous studies in order to set the NAIP magmatism in a time–space context. We suggest that global plate reorganizations and lithospheric extension across old orogenic fronts and/or suture zones, aided by other processes in the mantle (e.g. local or regional scale upwellings prior to and during the final Early Eocene rifting), played a role in the generation of the igneous products recorded in the NAIP for this period. These events gave rise to the extensive Paleocene and Eocene igneous rocks in W Greenland, NW Britain and at the conjugate E Greenland–NW European margins. Many of the relatively large magmatic centres of the NAIP were associated with transient and geographically confined doming in Early Paleocene times prior to the final break-up of the North Atlantic area.

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