Seamounts and oceanic igneous features in the NE Atlantic: a link between plate motions and mantle dynamics

A new regional compilation of seamount-like oceanic igneous features (SOIFs) in the NE Atlantic points to three distinct oceanic areas of abundant seamount clusters. Seamounts on oceanic crust dated 54–50 Ma are formed on smooth oceanic basement, which resulted from high spreading rates and magmatic productivity enhanced by higher than usual mantle plume activity. Late Eocene–Early Miocene SOIF clusters are located close to newly formed tectonic features on rough oceanic crust in the Irminger, Iceland and Norway basins, reflecting an unstable tectonic regime prone to local readjustments of mid-ocean ridge and fracture zone segments accompanied by extra igneous activity. A SOIF population observed on Mid-Miocene–Present rough oceanic basement in the Greenland and Lofoten basins, and on conjugate Kolbeinsey Ridge flanks, coincides with an increase in spreading rate and magmatic productivity. We suggest that both tectonic/kinematic and magmatic triggers produced Mid-Miocene–Present SOIFs, but the Early Miocene westwards ridge relocation may have played a role in delaying SOIF formation south of the Jan Mayen Fracture Zone. We conclude that Iceland plume episodic activity combined with regional changes in relative plate motion led to local mid-ocean ridge readjustments, which enhanced the likelihood of seamount formation

The pre-breakup stratigraphy and petroleum system of the Southern Jan Mayen Ridge revealed by seafloor sampling

The authors would like to acknowledge the contribution from the vessel’s crew (captain I. Rasmussen) and operator (Thor Ltd), the two surveyors (K. Høysæth and H.B. Bortne), and two sampling assistants (F. Gausepohl and A.-M. Voelsch). Sverre Planke and Dougal Jerram are partly funded through a Norwegian Research Council Centers of Excellence project (project number 223272, CEED). Adriano Mazzini is funded by the European Research Council under the European Union's Seventh Framework Programme Grant agreement n° 308126 (LUSI LAB project, PI A. Mazzini). TGS and VBPR funded the cruise and allowed the publication of the data and interpretation. Steve Killops from APT refined our interpretation of the biomarker data. The reviewers and the editor are also thanked for their constructive comments. Finally, this article is dedicated to the biostratigrapher Haavard Selnes who sadly passed away in 2015.Peer reviewedPostprin

Regional distribution of volcanism within the North Atlantic Igneous Province

An overview of the distribution of volcanic facies units was compiled over the North Atlantic region. The new maps establish the pattern of volcanism associated with breakup and the initiation of seafloor spreading over the main part of the North Atlantic Igneous Province (NAIP). The maps include new analysis of the Faroe–Shetlands region that allows for a consistent volcanic facies map to be constructed over the entire eastern margin of the North Atlantic for the first time. A key result is that the various conjugate margin segments show a number of asymmetric patterns that are interpreted to result in part from pre-existing crustal and lithospheric structures. The compilation further shows that while the lateral extent of volcanism extends equally far to the south of the Iceland hot spot as it does to the north, the volume of material emplaced to the south is nearly double of that to the north. This suggests that a possible southward deflection of the Iceland mantle plume is a long-lived phenomenon originating during or shortly after impact of the plume

Pseudomonas syringae on plants in Iceland has likely evolved for several million years outside the reach of processes that mix this bacterial complex across earth’s temperate zones

Funding Information: Funding: This research was funded by (i) the Campus France/ Partenariat Hubert Curien Jules Verne Franco-Icelandic Exchange Program project 40885YF, (ii) the Ranis Icelandic Research Fund project 206801–051 and (iii) French National Research Agency (ANR) project SPREE-17-CE32-0004-01. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Here we report, for the first time, the occurrence of the bacteria from the species complex Pseudomonas syringae in Iceland. We isolated this bacterium from 35 of the 38 samples of angiosperms, moss, ferns and leaf litter collected across the island from five habitat categories (boreal heath, forest, subalpine and glacial scrub, grazed pasture, lava field). The culturable populations of P. syringae on these plants varied in size across 6 orders of magnitude, were as dense as 107 cfu g−1 and were composed of strains in phylogroups 1, 2, 4, 6, 7, 10 and 13. P. syringae densities were significantly greatest on monocots compared to those on dicots and mosses and were about two orders of magnitude greater in grazed pastures compared to all other habitats. The phylogenetic diversity of 609 strains of P. syringae from Iceland was compared to that of 933 reference strains of P. syringae from crops and environmental reservoirs collected from 27 other countries based on a 343 bp sequence of the citrate synthase (cts) housekeeping gene. Whereas there were examples of identical cts sequences across multiple countries and continents among the reference strains indicating mixing among these countries and continents, the Icelandic strains grouped into monophyletic lineages that were unique compared to all of the reference strains. Based on estimates of the time of divergence of the Icelandic genetic lineages of P. syringae, the geological, botanical and land use history of Iceland, and atmospheric circulation patterns, we propose scenarios whereby it would be feasible for P. syringae to have evolved outside the reach of processes that tend to mix this bacterial complex across the planet elsewhere.Here we report, for the first time, the occurrence of the bacteria from the species complex Pseudomonas syringae in Iceland. We isolated this bacterium from 35 of the 38 samples of angiosperms, moss, ferns and leaf litter collected across the island from five habitat categories (boreal heath, forest, subalpine and glacial scrub, grazed pasture, lava field). The culturable populations of P. syringae on these plants varied in size across 6 orders of magnitude, were as dense as 107 cfu g−1 and were com-posed of strains in phylogroups 1, 2, 4, 6, 7, 10 and 13. P. syringae densities were significantly greatest on monocots compared to those on dicots and mosses and were about two orders of magnitude greater in grazed pastures compared to all other habitats. The phylogenetic diversity of 609 strains of P. syringae from Iceland was compared to that of 933 reference strains of P. syringae from crops and environmental reservoirs collected from 27 other countries based on a 343 bp sequence of the citrate synthase (cts) housekeeping gene. Whereas there were examples of identical cts sequences across mul-tiple countries and continents among the reference strains indicating mixing among these countries and continents, the Icelandic strains grouped into monophyletic lineages that were unique compared to all of the reference strains. Based on estimates of the time of divergence of the Icelandic genetic lineages of P. syringae, the geological, botanical and land use history of Iceland, and atmospheric circulation patterns, we propose scenarios whereby it would be feasible for P. syringae to have evolved outside the reach of processes that tend to mix this bacterial complex across the planet elsewhere.Peer reviewe

Sub-surface geology and velocity structure of the Krafla high temperature geothermal field, Iceland : Integrated ditch cuttings, wireline and zero offset vertical seismic profile analysis

The research leading to these results has received funding from the European Community's Seventh Framework Programme under grant agreement No. 608553 (Project IMAGE). The VMAPP project run by VBPR, DougalEARTH Ltd. and TGS also contributed funding to the borehole characterization of the K-18 borehole. Landsvirkun is acknowledged for their effort and assistance in this work and in particular for allowing the use of the data from well K-18. We further acknowledge the support from the Research Council of Norway through its Centres of Excellence funding scheme, project 22372 (SP and DAJ).Peer reviewedPostprin

The Jan Mayen microcontinent and Iceland Plateau: Tectono-magmatic evolution and rift propagation

Understanding the geological evolution of an area of interest is the basis for any exploration assessment and decision making for the Icelandic government tied to their offshore licensing activity. The Jan Mayen microcontinent study was initially focused on the tectonic and volcanic development of the central part of the microcontinent – the Lyngvi ridge and the Jan Mayen southern ridge complex areas. To properly understand their formation, a comprehensive study of the Jan Mayen microcontinent and the Iceland Plateau rift region became necessary, in order to place the local region within the complex setting of the Northeast Atlantic. Consequently, a research project was proposed, which formed the basis for this doctoral work. The resulting project presents an in depth understanding of the microcontinent´s structural and magmatic foundation, and the establishment of a tectono- and volcano-stratigraphic framework that enables a clear link to the area´s complex geodynamic development. These objectives were achieved through detailed geological and geophysical mapping of the Jan Mayen microcontinent and the Iceland Plateau rift regions, including seismic-stratigraphic analysis of the sedimentary and igneous succession and their correlation to the study area´s conjugate margins. Kinematic modelling of the northeast Atlantic region has enabled the Cenozoic evolution of the Jan Mayen microcontinent and the Iceland Plateau rift region to be reconstructed and placed within the context of continental breakup, subsequent plate reorganization, and interlinkage of the Northeast Atlantic rift system to the Iceland mantle anomaly. This research project was established and its dissertation was written in collaboration between the Institute of Earth Sciences (IES) of the University of Iceland, the Iceland GeoSurvey (ÍSOR), the Centre for Earth Evolution and Dynamics (CEED) at the University of Oslo, the British Geological Survey (BGS) and successively the University of Adelaide. The start of the project ran concurrent with the NAGTEC project, which was a collaboration between the NW European geological surveys, including ÍSOR, and oil companies that produced a tectonostratigraphic atlas of the Northeast Atlantic as well as a comprehensive geological and geophysical database. During that work, the primary database for the project was established by the candidate, who played a key role to assemble and compile data packages for several working groups (WP1: Tectonostratigraphy; WP3: Crustal Structure; WP4: History of Igneous Provinces; or WP5: Data) within the NAGTEC project that concerned matters of the Jan Mayen microcontinent, the Iceland Plateau rift areas, and their links into the conjugate margins. Parallel to the NAGTEC and collaboration projects, was the candidate managing and initiating the first digital offshore database of for Icelandic waters, with the focus on the JMMC-IPR region, a database that is now being steadily expanded for the Icelandic shelf area by a small Icelandic offshore research community. Collaboration projects were pursued at the same time, as it was imminent and necessary to increase data coverage and understanding of the JMMC-IPR area´s regional ties to its conjugate margins and oceanic domains. These concerned a high-resolution magnetic survey and analysis of the Ægir ridge by the Norwegian Geological Survey (NGU), and a detailed mapping project of the Jameson Land basin in collaboration with the Geological Survey of Denmark and Greenland (GEUS) and are both specifically acknowledged here. Both, enabling a good data-based comparison the study area and its oceanic domains, and provided a better understanding of the central East Greenland onshore and shelf margin areas.This study focused on the tectono-magmatic reconstruction of the Jan Mayen microcontinent (JMMC) and Iceland Plateau Rift (IPR) in context to the breakup and opening processes of the Northeast Atlantic region. Joint interpretation of densely spaced reflection seismic data and other geophysical and geological datasets, has illuminated the complex rift relocations associated with the formation of the JMMC, a narrow section of continental crust that was detached from the central East Greenland margin during the opening of the Northeast Atlantic and activation of the Iceland Plateau Rift. The IPR represents an igneous domain consisting of four distinct stages of rifting (IPR-I to IV) each corresponding to a structural domain. A tectonic-kinematic model was constructed by utilizing structural, volcano-stratigraphic and igneous-province-mapping based on vintage and new geological, geophysical, and geochemical datasets (1960s–2017). Eleven Cenozoic seismic-stratigraphic units, define the stratigraphic framework, bound by ten unconformities and disconformities. Six of these boundaries are regional and reflect discrete tectonostratigraphic phases in the evolution of the Northeast Atlantic region. Eocene to Miocene overlapping ridge segmentation developed during seven distinct tectono-magmatic phases, initially along the Ægir Ridge and subsequently along the northward propagating Iceland Plateau Rift, that interlinked the microcontinent with the anomalous Greenland-Iceland-Faroe ridge, prior to the subaerial formation of Iceland: (1) Pre-breakup to initial breakup phase during Paleocene (~63-56 Ma), characterized by extension, fracture and rift zone formation, followed by plateau basalt emplacement of the North Atlantic igneous province; (2) Syn-breakup during Early Eocene (∼55-53 Ma), with stepwise north-to-south development of seaward-dipping reflectors along the microcontinent´s north-eastern margin and NV-SE striking fracture zone segments, prior to spreading at the Ægir ridge; (3) Full breakup along the microcontinent´s eastern margin and initiation of IPR-I during Early-Mid Eocene (~53-50 Ma); (4) Rift-transfer during Eocene (∼49-36 Ma), characterized by SW to NE magmatic propagation within the JMMC domain and forming of the IPR-II segment intersecting IPR-I, contemporary with cessation of spreading at the Ægir ridge; (5) Ridge transfer and tectonic re-arrangement during Late Eocene to Oligocene (~36-25 Ma) was associated with the formation of segment IPR-III, the south-western Jan Mayen igneous province, and the Jan Mayen trough, separating the Jan Mayen southern ridge complex from the main Jan Mayen ridge through SW-NE rift propagation. These events were accompanied by large scale intrusion and flood basalts, in clear proximity to the Iceland hotspot. (6) Final breakup during Late Oligocene (25-22 Ma) with emplacement of a second igneous breakup margin along the western flank of the microcontinent in conjunction with the formation of the IPR-IV and the proto-Kolbeinsey ridge, and the initiation of the proto-Iceland shelf region. (7) Full separation of the JMMC-IPR domains from the central East Greenland margin during Miocene (22-0 Ma) and spreading along the Kolbeinsey ridge. In summary, the initiation of the fanned-shaped Iceland Plateau Rift and the Jan Mayen microcontinent´s southern ridge complex was accompanied by crustal breaches and melt incursions that formed several axial rift systems and volcanic ridges. The JMMC-IPR igneous domains portray the complexity of a long-lived (Eocene to Miocene) volcanic margin within an unstable rift-transfer tectonic setting. This region represents a unique analogue Iceland-type crust; the systematic build-up of up to 10-14 km thick oceanic crust and reactivation of pre-existing structural complexes by mantle anomalies; rift-transfer processes; and overlapping sub-aerial and sub-surface igneous activity in conjunction with microplate formation.Meginmarkmið þessa verkefnis var að auka skilning okkar á uppruna og þróun Jan Mayen svæðisins (JMMC) og rekbelta Íslandssléttunnar (Iceland Plateau Rift, IPR), í samhengi við opnunarferli og reksögu NA-Atlantshafssvæðisins, norðan Íslands. Myndunarsaga JMMC er tvískipt; rek eftir Ægishrygg, við opnun Atlantshafsins, klauf miðhluta Austur-Grænlands frá Noregi, og IPR-rekbeltið innan Íslandssléttunnar, vestan Ægishryggjar, klauf JMMC frá Austur Grænlandi. IPR-rekbeltið skiptist í fjögur aðskilin svæði, í tíma og rúmi. Endurskoðað og ítarlegra líkan af jarðlagafræði, eldvirkni og jarðskorpuhreyfingum svæðisins byggir á samtúlkun jarðfræðilegra, jarðeðlisfræðilegra og jarðefnafræðilegra gagna sem aflað var á árunum 1960 til 2017; fjölgeislamælingum; endurkast- og bylgjubrotsgögnum; þyngdar-, og segulmælingum, borholugögnum og bergsýnum, sem og samanburði við aðlæg svæði. Jarðlagastafli tertíer- og kvartertímans skiptist í ellefu jarðlagasyrpur sem afmarkast af tíu mismunandi mislægjum. Sex tengjast stærri, jarðsögulegum atburðum í reksögu NorðurAtlantshafssvæðisins, önnur svæðisbundnari rofmislægjum. Reksaga svæðisins skiptist í sjö tímabil eldvirkni og skerhreyfinga, sem endurspegla óstöðugleika í jarðskorpuhreyfingum yfir 30 milljón ára tímabil, frá því Atlantshafið opnaðist um Ægishrygg og innan framsækna, skástíga, IPR rekbeltisins. Upprunalega tengdist IPR rekbeltið Grænlands-(Íslands)- Færeyjahrygg en færðist síðan til norðurs, og hóf að éta sig inn í meginlandsskorpu Jan Mayenhryggjar. Samhliða þróun IPR-rekbeltisins, minnkaði rekhraði á sunnanverðum Ægishrygg. Í hnotskurn er þróunarsagan eftirfarandi: (1) Gliðnun innan Laurasíuflekans hófst á paleósentímabilinu (fyrir ~63-56 milljónum ára). Upphaflega myndaðist mikill sigdalur norðan og austan JMMC, sem samanstóð af lægum brotabeltum. Áframhaldandi tog varð til þess að meginlandsskorpan slitnaði og úthafsskorpa myndaðist við öflugt uppstreymi möttulefnis og mikil flæðigos sem mynduðu stór basaltsvæði (North Atlantic Igneous Province). (2) Byrjun eósentímans (fyrir ~55-53 milljónum ára), einkenndist af myndun mikilla flæðibasaltlaga, innan skástígra gosbelta sem þróuðust frá norðri til suðurs eftir norðausturbrún JMMC. Flæðibasaltlögunum (seaward dipping reflectors) hallar í átt að Ægishrygg í Noregsdjúpi. Svæðið opnaðist eftir með NV-SA-lægum brotabeltum, hraun runnu á landi og í sjó, með móbergsmyndunum og móbergssetlögum á grunnsævi. (3) Í kjölfar þess að Ægishryggur aðskilur Grænland frá Noregi snemma á eósen (~53-50 Ma), þróast framsækið rekbelti (IPR-I) við suðurenda hryggjarins, og norðurbrún Íslands-Færeyjahryggjarins. (4) Gosbeltaflutningar á mið og seinni hluta eósen (∼49-36 Ma) og myndun Íslandssléttunnar. Landrek með innskotavirkni frá SV til NA eftir IPR-I og síðan IPR-II rekásunum innan Íslandssléttunnar, yfirtekur suðurhluta Ægishryggjar, þar sem gliðnun og jarðskorpumyndun minnka til muna. (5) Eósen-ólígósen (∼36-25 Ma): IPR-III rekásinn með SV-NA stefnu klífur suðurenda Jan Mayen frá Lyngvahrygg við Hlésund og Suðurhryggir Jan Mayen verða til. Tímabilinu fylgdi aukið uppstreymi kviku til norð-norðausturs, undir áhrifum frá Íslands heita reitnum með tilheyrandi aukningu í innskota- og eldvirkni samfara myndun flæðigossyrpna meðfram sigdölum gosbeltanna. (6) Síð-ólígósen (∼25-22 Ma): Landrek meðfram vesturbrún JMMC innan IPR-IV rekássins með flæðisgossyrpum, IPR-IV er fyrirrennari Kolbeinseyjarhryggjar sem markar upphaf norðausturlandsgrunns Íslands. (7) Míósen til nútíma (22-0 Ma): Með myndun Kolbeinseyjarhryggjar slitnar JMMC endanlega frá Grænlandi og úthafsskorpa verður til. Verkefnið hefur varpað nýju ljósi á 30 milljón ára þróunarsögu JMMC, og hvernig suðurhryggirnir urðu til, í framsæknu gosbelti innan Íslandssléttunnar, undir áhrifum af Íslands heita reitnum, sem yfirtók rek á sunnanverðum Ægishrygg. Öflug innskotavirkni og eldvirkni innan skástígra goskerfa, einkenna innviði Íslandssléttunnar og endurspegla fjölþættar gliðnunar- og skerhreyfingar eftir flekaskilunum sem rekja má í endurkastsgögnunum. Tektónísk þróun rannsóknarsvæðisins er í mörgu lík Íslandi í dag, bæði einkennast af óstöðugum, framsækum rekbeltum, með innskotavirkni í gegnum eldri jarðlagastafla.This research project was conducted at the University of Iceland, funded by the National Energy Authority of Iceland (Orkustofnun) and the Iceland GeoSurvey. I specifically thank the Iceland GeoSurvey and the Earth Sciences department at the University of Iceland for supporting me to finalize this project during its final stages. This project evolved in parallel with the NAGTEC (Northeast Atlantic Geoscience TECtonostratigraphic Atlas) and the NORDMIN (TemaNord 2016:562) projects. Support from industry sponsors of NAGTEC is gratefully acknowledged, just as the support through the Research Council of Norway through its Centres of Excellence funding scheme, project number 223272.Final and defended PhD dissertation

Break-up and seafloor spreading domains in the NE Atlantic

An updated magnetic anomaly grid of the NE Atlantic and an improved database of magnetic anomaly and fracture zone identifications allow the kinematic history of this region to be revisited. At break-up time, continental rupture occurred parallel to the Mesozoic rift axes in the south, but obliquely to the previous rifting trend in the north, probably due to the proximity of the Iceland plume at 57-54 Ma. The new oceanic lithosphere age grid is based on 30 isochrons (C) from C24n old (53.93 Ma) to C1n old (0.78 Ma), and documents ridge reorganizations in the SE Lofoten Basin, the Jan Mayen Fracture Zone region, in Iceland and offshore Faroe Islands. Updated continent-ocean boundaries, including the Jan Mayen microcontinent, and detailed kinematics of the Eocene- Present Greenland-Eurasia relative motions are included in this model. Variations in the subduction regime in the NE Pacific could have caused the sudden northwards motion of Greenland and subsequent Eurekan deformation. These events caused seafloor spreading changes in the neighbouring Labrador Sea and a decrease in spreading rates in the NE Atlantic. Boundaries between major oceanic crustal domains were formed when the European Plate changed its absolute motion direction, probably caused by successive adjustments along its southern boundary.</p

Seamounts and oceanic igneous features in the NE Atlantic: A link between plate motions and mantle dynamics

A new regional compilation of seamount-like oceanic igneous features (SOIFs) in the NE Atlantic points to three distinct oceanic areas of abundant seamount clusters. Seamounts on oceanic crust dated 54-50 Ma are formed on smooth oceanic basement, which resulted from high spreading rates and magmatic productivity enhanced by higher than usual mantle plume activity. Late Eocene-Early Miocene SOIF clusters are located close to newly formed tectonic features on rough oceanic crust in the Irminger, Iceland and Norway basins, reflecting an unstable tectonic regime prone to local readjustments of mid-ocean ridge and fracture zone segments accompanied by extra igneous activity. A SOIF population observed on Mid-Miocene-Present rough oceanic basement in the Greenland and Lofoten basins, and on conjugate Kolbeinsey Ridge flanks, coincides with an increase in spreading rate and magmatic productivity. We suggest that both tectonic/ kinematic and magmatic triggers produced Mid-Miocene-Present SOIFs, but the Early Miocene westwards ridge relocation may have played a role in delaying SOIF formation south of the Jan Mayen Fracture Zone. We conclude that Iceland plume episodic activity combined with regional changes in relative plate motion led to local mid-ocean ridge readjustments, which enhanced the likelihood of seamount formation.</p

CRUSMID-3D : Crustal Structure and Mineral Deposit Systems: 3D-modelling of base metal mineralization in Jameson Land (East Greenland)

Providing research and education at a high international level is a prerequisite for the raw material sector to develop competitive and cost effective exploration methods. The NordMin project CRUSDMID-3D is a consortium between research institutes, academia and SME supporting a PhD project to study some of the geological processes in Greenland that are related to ore deposits, to understand the relationships between structures and mineralization. The new geological and structural data together with aeromagnetic/electromagnetic surveys and the drill-core data added new values to the regional knowledge of East Greenland. The exploration tools developed within the PhD-project are expected to be useful in planning and executing future exploration campaigns in similar but also other geological environments

Gas seepage pockmark microbiomes suggest the presence of sedimentary coal seams in the Oxarfjordur graben of NE-Iceland

Natural gas seepage pockmarks are found off- and onshore in the Öxarfjörður graben, Iceland. The bacterial communities of two onshore seepage sites were analysed by 16S rRNA gene amplicon sequencing; the geochemical characteristics, hydrocarbon content, and the carbon isotope composition of the sites were also determined. While one site was found to be characterised by biogenic origin of methane gas, with a carbon isotope ratio (δ13C (‰)) of −63.2, high contents of organic matter and complex hydrocarbons, the other site showed a mixed origin of the methane gas (δ13C (‰) = −26.6) with geothermal characteristics and lower organic matter content. While both sites harboured Proteobacteria as the most abundant bacterial phyla, the Deltaproteobacteria were more abundant at the geothermal site and the Alphaproteobacteria at the biogenic site. The Dehalococcoidia class of phylum Chloroflexi was abundant at the geothermal site while the Anaerolineae class was more abundant at the biogenic site. Bacterial strains from the seepage pockmarks were isolated on a variety of selective media targeting bacteria with bioremediation potential. A total of 106 strains were isolated and characterised, including representatives from the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. This article describes the first microbial study on gas seepage pockmarks in Iceland.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author