scholarly journals Platinum-group element signatures in the North Atlantic Igneous Province: Implications for mantle controls on metal budgets during continental breakup

Lithos ◽  
2015 ◽  
Vol 233 ◽  
pp. 89-110 ◽  
Author(s):  
Hannah S.R. Hughes ◽  
Iain McDonald ◽  
Andrew C. Kerr
Keyword(s):  
North Atlantic ◽  
Platinum Group Element ◽  
Group Element ◽  
Continental Breakup ◽  
The North ◽  
Igneous Province ◽  
The North Atlantic ◽  
Platinum Group ◽  
North Atlantic Igneous Province

Diversity of platinum-group element mineralization styles in the North Atlantic Igneous Province: new evidence from Rum, UK

2003 ◽  
Vol 140 (5) ◽  
pp. 499-512 ◽  
Author(s):  
M. R. POWER ◽  
D. PIRRIE ◽  
J. C. Ø. ANDERSEN
Keyword(s):  
North Atlantic ◽  
Platinum Group Element ◽  
Platinum Group Elements ◽  
Group Element ◽  
The North ◽  
Igneous Province ◽  
Two Generations ◽  
Platinum Group ◽  
New Evidence ◽  
North Atlantic Igneous Province

Two generations of sulphide-hosted platinum-group element mineralization occur in the West Sgaorishal ultramafic plug, Rum. Disseminated Cu and Ni sulphides around the margin of the plug host a restricted platinum-group mineral assemblage that is dominated by Pd bismutho-tellurides and sperrylite (PtAs2) with subordinate electrum (AuAg), froodite (PdBi2) and unidentified Pt–Bi–Te phases. Later sulphide-rich dykes cross-cut the plug and host an assemblage dominated by Pd bismutho-tellurides, sperrylite and locally very abundant paolovite (Pd2Sn). Whole rock combined platinum-group element+Au concentrations are proportional to the sulphide abundance with slightly elevated values in disseminated sulphide lithologies (>400 ppb) and very high values (>2000 ppb) in the sulphide-rich dykes. Both generations have relatively flat chondrite-normalized plots indicating a primitive magmatic source. Negative δ34S values (−9.2 to −18.3 ‰) indicate that the disseminated mineralization is due to contamination probably derived from Jurassic sedimentary rocks leading to sulphur saturation and collection of platinum-group elements. The sulphide-rich dykes must have entrained a platinum-group element-rich sulphide liquid collected from a much larger volume of magma. The presence of platinum-group elements and sulphide-rich dykes with δ34S values between −10.8 and −15.0 ‰ indicates that parts of the Rum Layered Suite became sulphur saturated through magmatic contamination. It appears likely that platinum-group element mineralization styles within the southern North Atlantic Igneous Province are diverse and may be present in a wider variety of mineralogical associations than previously recognized.

scholarly journals Distinct sulfur saturation histories within the Palaeogene Magilligan Sill, Northern Ireland: implications for Ni – Cu – platinum group element mineralisation in the North Atlantic Igneous Province

2019 ◽  
Vol 56 (7) ◽  
pp. 774-789
Author(s):  
Jordan J. Lindsay ◽  
Hannah S.R. Hughes ◽  
Dermot Smyth ◽  
Iain McDonald ◽  
Adrian J. Boyce ◽  
...  
Keyword(s):  
North Atlantic ◽  
Platinum Group Element ◽  
Crustal Contamination ◽  
Group Element ◽  
Olivine Gabbro ◽  
Plumbing System ◽  
The North ◽  
Igneous Province ◽  
The North Atlantic ◽  
Platinum Group

The ∼60 m thick Magilligan Sill is part of the British Palaeogene Igneous Province in the North Atlantic. The sill comprises layers of dolerite and olivine gabbro, and it intrudes a thick sequence of Mesozoic mudstones and marls, which are locally baked at the sill margins. Since 2014, the sill has been an exploration target for orthomagmatic Ni – Cu – platinum group element (PGE) sulfide mineralisation analogous to the Noril’sk-Talnakh intrusion in Russia. We present new petrological, geochemical, and S isotope data to assess the prospectivity of the sill and the underlying magmatic plumbing system. Most sulfides in the dolerite portions of the sill are <50 μm in size and comprise only pyrite with PGE abundances below the detection limit. In the olivine gabbros, >150 μm size pentlandite, chalcopyrite, and pyrrhotite grains contain <4 ppm total PGE, 1460 ppm Co, and 88 ppm Ag. Pyrite from the dolerites have δ34S ranging from −10.0‰ to +3.4‰ and olivine gabbro sulfides range from −2.5‰ to −1.1‰, suggesting widespread crustal contamination. The S/Se ratios of sulfides in the dolerites and olivine gabbros range from 3500 to 19 500 and from 1970 to 3710, respectively, indicating that the latter may have come from upstream in the magma plumbing system. The Magilligan Sill records multiple injections of mafic magma into an inflating sill package, each with distinct mechanisms towards S saturation. Whilst the sulfide minerals in the sill do not constitute significant mineralisation themselves, detailed in situ studies highlight a divergence in S saturation histories and suggest that a larger volume of olivine gabbro sulfides at depth may be prospective.

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

&lt;p&gt;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 &lt;sup&gt;13&lt;/sup&gt;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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;This work is financed and carried out within the framework of the BRGM-TOTAL Source-to-Sink project.&lt;/p&gt;

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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