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

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


Title: The Jan Mayen microcontinent and Iceland Plateau: Tectono-magmatic evolution and rift propagation
Author: Blischke, Anett   orcid.org/0000-0001-8854-4499
Advisor: Bryndís Brandsdóttir
Date: 2020-05-15
Language: English
Scope: 1-336
University/Institute: Háskóli Íslands
University of Iceland
School: Verkfræði- og náttúruvísindasvið (HÍ)
School of Engineering and Natural Sciences (UI)
Department: Jarðvísindadeild (HÍ)
Faculty of Earth Sciences (UI)
ISBN: 978-9935-9412-8-2
Subject: Dual-breakup igneous complex; Kinematic model; Iceland plateau rift; Jan Mayen microcontinent; SDRs; Volcanic seismic-stratigraphy; Jarðskorpuhreyfingar; Landrek; Jarðlög; Jarðeðlisfræði; Doktorsritgerðir
URI: https://hdl.handle.net/20.500.11815/1826

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Citation:

Anett Blischke, 2020, The Jan Mayen microcontinent and Iceland Plateau: Tectono-magmatic evolution and rift propagation, PhD dissertation, Faculty of Earth Sciences, University of Iceland.

Abstract:

 
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.
 

Description:

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.

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