1 Introduction

The mid Norwegian passive margins has been studied well as a volcanic margin which mainly

belongs to the North Atlantic Igneous Province. The North Atlantic Igneous Province has been

studied and associated with the intrusive and massive extrusive magmatism which happened to be

as a result of the see floor spreading and the continental break up (Berndt, 2001).

Figure 1 (Regional Setting of the Norwegian Margins)

These magmatism are covered by the magnesium contents and the iron contents mostly calling the

“Mafic rock”. The margin has a history of spanning between the Early Eocene break-up & the

Carboniferous and episodic rifting. During the period of the extensional stress field, it resulted into

the oblique formation of younger rifts over the older rifts. Various studies have been conducted on

the mid Norwegian margin collecting the seismic refraction data, experimental drilling & the

commercial drilling on the Voring plateau & the continental shelf (Callot, 2011).

2 Volcanic Passive Margins

The large igneous provinces have been found of having volcanic passive margins (VPM). These

igneous provinces are said to be comprised of the transitional narrow crust which is formed due to

the rifting over the hot mantle and the continental breakup. A volcanic passive margin can be

characterized by the following attributes; firstly massive intrusion of the dyke and sill happens into

the sediments. Secondly, the lava flows reflect dipping seaward and thirdly, the ultra-mafic and

the mafic intrusion happen into the middle and the upper continental crust. Presence of seismic

velocity bodies is also found to be present at the lower crust which cause the magma under-plating

(Eldholm & Grue, 1994). The continental breakup during the Late Paleocene and the Early Eocene

resulted in the spreading of the magmatism which developed into the intrusive and extrusive

structures alongside the mid-Norwegian margin.

Figure 2 (Structural Map Related to the Rifting Phases)

3 Mid-Norwegian Volcanic Passive Margin

The mid Norwegian margin is constituted by three segments mainly i.e. Voring, More and Lofoten-

Vesteralen. These three segments are separated by the Bivrost Lineament zone and East Jan Mayen

Fracture and each has the length of 400 – 500 km. On the margins of More Basin and Voring

segments, a lower crustal body has been developed which is characterized by P-wave velocities

forming the thickened crust beneath them and continue to the thick western oceanic crust (Faleide,

2008). The md Norwegian margin is said to be formed due to the tectono-magmatic evolution in

the following three ways. Firstly, the change of the accretionary magma volumes from normality

to the maturation and continental margin subsidence. Secondly, lithospheric extension has

occurred due to the rift episode in Cretaceous-Paleocene which led to the plate separation and

breakup. Thirdly, the central rift tend to enhance the igneous activity and uplift it during the late

rifting and culmination of voluminous outbursts of the Early Eocene’s basaltic lavas. These three

tectono-magmatic evolution described the formation of mid Norwegian margins and the increased

igneous activity (Gernigon, 2004).

3.1 The More Margin

The more margin is largely comprised of the deep and wide More Basin, Gentle/ wide slope

consisting of the thick Cretaceous fill. The inner flank is dipped basin ward in a steep way and the

curst which is crystalline in nature gets thin rapidly reaching to smaller than ten kilometer. The

More Basin is mainly comprised of the sub basins which are segregated by the Jurassic-Early

Cretaceous rift that formed the intra-basinal highs between the sub basins. The sedimentary

succession further gets thinner and deeper decreasing to twelve kilometer landwards. The

structural relief in the More Basin was filled mainly during the Mid-Cretaceous time while

intrusions are still wide spreading within this crust getting deepened in the western and central

parts of the More Basin (Lundin, 2013).

The western part of the More Basin is covered by the lava flows as well as a thick LCB with lower

than seven kilometer P-wave velocity is evident to be present under the Basin covering most of its

part. The magmatic under-plating is being evident during the interpretations of the body related to

the breakup of the crust. It has also been researched and found that the More marginal heights,

shallowing of the Cretaceous sediment, crystalline crust thickening and the making of crystalline

basement all occur near the ocean-continent transition. These mid Norwegian margins are evolved

through a process of rifting episodes and breakups related to the Cretaceous sediments which

ultimately resulted in the formation of Greenland margins and the mid Norwegian margins. The

complex structure of these volcanic margins have been studies by various researchers in order to

investigate their formation and expansion with the passage of time (Scheck-Wenderoth, 2007).

The East Greenland Margins and the NW European margins have a distinct history associated to

their development starting from the post-Caledonian orogenic backsliding to the post-Eocene

passive margin formation. The evolutionary process has been given in the later section of this

report.

3.2 The Voring Margin

It is comprised of the northwest to the southeast area, the Voring Basin, the Halten terraces, the

Voring Marginal High, the Trondelag platform and the Donna terraces. The platform is highly

stable since the deep basins got filled by the upper Paleozoic sediment and the Triassic sediment

including the deep basins which were filled during the Jurassic time. The deep MCS profiles and

the seismic refraction profiles which are wide-angle are mostly constrained by the deep Moho

reaching about thirty two kilometer close to the mainland in Norway. Like the More Basin, the

Voring Basin can also be divided into the highs and the sub Basins reflecting the vertical

movements during the Early Cretaceous and the Late Jurassic basin evolutions (Raum, 2011).

The deep Moho undulates at twenty five kilometer under the deep basin while the velocity reaches

to the 7.6 km in most of the area under the lower crust and the magmatic under-plating. A study

conducted by Gernigon et al (2004) to investigate the formation of the mid Norwegian margins

and the Basins reveals the alternative interpretation of the LCB. It included the melted continental

crust, inherited high pressure eclogite & granulite rocks, the mantle rocks and the description of

the thickness of the body. It has been said in that study that the thickness of the body varies within

the area and these variations could be the result of the spatial variations which was caused during

the magma distribution process or the variations during the pre-breakup structures. The Voring

Margin is comprised of the Voring Escarpment and the Voring Marginal Highs consisting of the

landward part of continental stretched crust and the outer part of an oceanic crust which is thick

anomalously covered by the Early Eocene basalts (kogseid, 2000).

4 The Process of Margin Evolution

4.1 Pre-breakup Basin Evolution

The structural pre-opening and the margin framework has caused the development of the Voring

and the More Basins of the mid Norwegian region which is characterized by the Late Jurassic &

Early Cretaceous rifting activity in the NE Atlantic-Arctic region. A considerable thinning and

crustal extension during the Earliest Cretaceous rifting activity led to the formation of the

Cretaceous basin of mid Norwegian VPM as well as the development of the East Greenland in the

Southwestern Barents Sea. However, in a study conducted by Skogseid (2000), it has been said

that no distinct structures have been identified associated to the Voring Basin. But in the mid

cretaceous time, the structural relief in the Voring and the More Basins was filled with the thick

upper Cretaceous strata (Blystad, 1995).

4.2 Break up Related Magmatism and Tectonism

At the onset of the pre-breakup related rifting of the NE Atlantic, the area between the Greenland

Margins and the NW Europe got extensively weakened caused by the previous rifting. This rifting

resulted afterwards in the detachment structures of the thick Cretaceous sequence and the intra-

crustal levels of the Voring Basin. Lately, the rifting episodes were taken up by the deformation

of the De Geer Zone resulting in the pull-apart formation of the SE Barents. Tectonic

reorganization happened during this era and the Greenland moved in a direction to the west of the

Eurasia. Marin shallowing occurred and the rifting related to the relative plate motion caused the

reactivation of the Volcanic Province (Eldholm & Grue, 1994).

4.3 Post-breakup Margin Evolution

The modest sedimentation and the regional subsidence in the Norwegian- Greenland Sea resulted

into the development of the mid Norwegian margin. The deep water sedimentation in the Miocene

succession expanded the sediment drifts of the contrite. Plate tectonic reconstruction occurred and

it impact mainly the ocean circulation which resulted into the deep water exchanges through a

southern gateway of the Scotland- Greenland Ridge (Lundin, 2013). At the western side of the

Barents Sea, a pre-glacial tectonic uplift occurred and led to the formation of the Vestbakken

Volcanic Province. These glacial tectonic components composed over a half of the total area of

the mid Norwegian margins afterward. The continental margins as well as the mid Norwegian

margins have been opened in the response of the Greenland- Norwegian Sea as main rifting,

exhibiting the distinct segmentation of structural inheritance which extend back to the pre-breakup

history (Faleide, 2008).

5 Works Cited

Berndt, C. (2001). Seismic volcanostratigraphy of the Norwegian Margin: constraints on

tectonomagmatic break-up processes. Journal of the Geological Society.

Blystad, P. (1995). Structural elements of the Norwegian continental shelf Part II: the Norwegian

Sea Region: NPD-Bulletin, . The Norwegian Petroleum Directorate.

Callot, J. (2011). Development of volcanic passive margins: Two‐dimensional laboratory models.

Tectonics.

Eldholm, O., & Grue, K. (1994). North Atlantic volcanic margins: dimensions and production

rates. Journal of Geophysical Research: Solid Earth.

Faleide, J. (2008). Structure and evolution of the continental margin off Norway and the Barents

Sea: Episodes. The Journal of Geography.

Gernigon, L. (2004). Deep structures and breakup along volcanic rifted margins: insights from

integrated studies along the outer Vøring Basin (Norway). Marine and Petroleum Geology.

kogseid, J. (2000). NE Atlantic continental rifting and volcanic margin formation, in NOTTVEDT,

A. e. a., ed., Dynamics of the Norwegian Margin, Volume 167. London, Geological

Society.

Lundin, E. (2013). Repeated inversion and collapse in the Late Cretaceous–Cenozoic northern

Vøring Basin, offshore Norway. Petroleum Geoscience.

Raum, T. (2011). The transition from the continent to the ocean: a deeper view on the Norwegian

margin. Journal of the Geological Society,.

Scheck-Wenderoth, M. (2007). The transition from the continent to the ocean: a deeper view on

the Norwegian margin. Journal of the Geological Society,.

6 Additional Explanation

Continental breakup and initial seafloor spreading in the North Atlantic area was accompanied by

widespread intrusive and extrusive magmatism and the formation of North Atlantic Large Igneous

province (NAIP) (White and McKenzie, 1989; Coffin and Eldholm, 1994; Saunders et al., 1997).

The continental breakup associated with massive transient igneous activity gave rise to volcanic

passive margins. Magmatic activity is typically expressed within the stretched continental crust

by: (1) large wedges of seaward-dipping basaltic flows and tuffs extruded at the surface (SDRs)

(Eldholm, 1991; Hinz, 1981; Planke et al., 2000); (2) massive sill/dyke intrusions within the

sedimentary basin (Planke et al., 2005; Svensen et al., 2004); (3) intense intrusions into the upper

and mid continental crust by mafic to ultramafic intrusions (Abdelmalak et al., 2015; Geoffroy et

al., 2007; Karson and Brooks, 1999; Klausen and Larsen, 2002; Lenoir et al., 2003; Meyer et al.,

2009); and (4) the presence of a seismic lower crustal body (LCB) at the base of the crust showing

high Vp velocity (Vp> 7.0 km/s) (Holbrook et al., 2001; Kelemen and Holbrook, 1995; Mjelde et

al., 2009a; Mjelde et al., 2009b; White et al., 1987).

The conjugate volcanic rifted margins along the NE Atlantic are the major magmatic component

of the North Atlantic Large Igneous Province formed during the final fragmentation of Pangea

within the Early Cenozoic (Ganerød et al., 2010; Hansen et al., 2009; Meyer et al., 2007; Saunders

et al., 1997; Torsvik et al., 2001). The onset of continental breakup during Paleocene-Eocene

transition marked a culmination of a ~350 m.y. period of predominantly extensional deformation

and intermediate cooling events subsequent to the Caledonian orogeny (Doré et al., 1999; Skogseid

et al., 2000; Tsikalas et al., 2008; Ziegler, 1988). Continental breakup and initial seafloor spreading

resulted in voluminous igneous activity generating both intrusive and extrusive complexes

constituting the breakup-related igneous rocks. Based on seismic refraction data, the velocity

structure of the different segments of the North Atlantic area reveals the presence of high-velocity

lower crustal body (reef: voss, jokat holbrooh, mjelde….). The Lower crustal body has been

recognized along many parts of the North Atlantic margins. and is commonly interpreted to

represent magmatic material added beneath the crust (Eldholm & Grue 1994; Mjelde et al. 2001),

or intruded in the lower crust (e.g. White et al. 1987, 2008; White & Smith 2009). Notably, the

interpreted magmatic body has been proposed to constitute between 60 and 80% of the total

magmatic rock volume in the NAIP (White et al. 1987, 2008; Eldholm & Grue 1994).

-----

The mid-Norwegian margin, belonging to the North Atlantic Igneous Province, is considered as a

typical volcanic margin. This margin is probably one of the most extensively studied continental

margins. The mid Norwegian margin has been investigated by multichannel seismic reflection data

(Blystad et al., 1995; Brekke et al., 2001; Eldholm et al., 1989a; Gernigon et al., 2003; Skogseid

and Eldholm, 1989), seismic refraction data (Breivik et al., 2014; Faleide et al., 2010; Faleide et

al., 2008; Mjelde et al., 2009b; Mjelde et al., 1992; Mjelde et al., 2003; Talwani and Eldholm,

1972), exploration drilling on the continental shelf and scientific drilling on the Vøring Plateau

(Eldholm et al., 1989a, b; Eldholm et al., 1987; Skogseid and Eldholm, 1989). The mid-Norwegian

margin experienced a prolonged history of intermittent extension and basin formation events that

occurred in late Paleozoic-Triassic, Late Jurassic- Early Cretaceous and Late Cretaceous-

Paleocene times (Brekke, 2000; Eldholm and Grue, 1994; Faleide et al., 2010; Faleide et al., 2008;

Gernigon et al., 2004; Lundin and Doré, 2005; Tsikalas et al., 2012).

The Vøring margin, part of the Mid Norwegian Margin is bounded by the Jan Mayen Fracture

Zone/Jan Mayen corridor to the southwest and the Bivrost Lineament to the northeast (Blystad et

al., 1995). The ~500 km wide of the Vøring Margin comprises: the Trøndelag Platform, the Vøring

Basin and the Vøring Marginal High. The Vøring Margin is the consequence of a significant late

Jurassic to early Cretaceous crustal thinning phase, with episodic subsidence leading to a very

thick Cretaceous depocenter (Blystad et al., 1995; Skogseid et al., 2000; Scheck-Wenderoth et al.,

2007).

This significant sedimentary Cretaceous thickness (~10 km deep) mostly concealed the geometry

of the deeper syn-rift sequences in the Vøring Basin (Faleide et al., 2008). The thinned crust at

Vøring Margin was, again, the locus of a new phase of extensional deformation in the latest

Cretaceous. A last pre-breakup rifting phase is assumed for the latest Cretaceous-earliest Paleocene

period, particularly documented in the outer Vøring Basin (Eldholm et al., 2002; Gernigon et al.,

2003; Ren et al., 2003). The magmatic-tectonic processes which lead to the final breakup at the

Vøring Margin are restricted to a 100-150 km wide region of the outer Vøring Basin and Vøring

Marginal High presently situated to the east of the first oceanic magnetic chrons. At the Vøring

Margin significant volumes of flood basalts erupted in submarine to subaerial settings (e.g. Berndt

et al., 2001). This peculiar volcanic succession displays a large variety of seismic facies that are

indicative of the style of volcanic emplacement, depositional environment and subsequent mass

transport (Planke and Alvestad, 1999; Planke et al., 1999; Planke et al., 2000; Brendt et al., 2001).

The volcanic sequences emplaced during the onset of the breakup, partially masked seismically

the Late Cretaceous–Paleocene and older sedimentary strata and continental structures of the outer

Vøring and Møre Margins. Outside the lava flow domains, seismic observations report voluminous

magmatic complexes of dominantly sub-horizontal sheets (sills) intruding pre-breakup

sedimentary rocks during the opening of the North Atlantic, within the Vøring and Møre Basins.

The sill intrusions cover an area of more than 85000 km2 offshore mid-Norway (Planke et al.,

2005; Abdelmalak et al., Submitted).

As exploration in volcanic rifted margins increases, seismic data shot over significant lava cover

became more available. The increased availability of high-quality data and reinterpretation of old

data on rifted margins show that breakup magmatism is common, although its intensity and

character may vary significantly along margin and between margins. The understanding of the

temporal evolution of breakup volcanism has been, also, improved significantly by several deep-

sea drilling surveys: DSDP Leg 38 and ODP Leg 104 on the Vøring Margin (Eldholm et al., 1987;

Eldholm et al., 1989a; Planke, 1994) and ODP Legs 152 (Larsen and Saunders, 1998; Planke and

Cambray, 1998) and 163 (Larsen et al., 1999b) on the Southeast Greenland Margin. Recent

advances in processing of seismic data have improved imaging of geometries within the volcanic

deposits as well as in the sediments below the basalts and allow a better constraints and

interpretation of the breakup related igneous rocks. It is becoming clear that internal architecture

of flood basalt sequences is markedly heterogeneous (e.g. Jerram et al., 2009; Nelson et al., 2009a).

Furthermore improved multichannel seismic (MCS) data have allowed the definition and

characterization of a more dedicated seismic "volcanostratigraphy" based on their shape,

reflection pattern and boundary reflections (Planke et al., 2000; Berndt et al., 2001). Several

volcanic seismic facies units have been identified: (1) Landward Flows, (2) Lava Delta, (3) Inner

Flows, (4) Inner Seaward Dipping Reflectors (Inner SDR), (5) Outer High, (6) Outer SDR (Fig.

1). Such facies succession represents a typical volcanic rifted margin sequence and describes the

evolution of the breakup extrusive complex landward and/or very close to the first magnetic

seafloor spreading anomalies. These volcanic successions, which display a variety of reflection

configurations, are indicative of the depositional environment and the subsequent mass transport

(e.g. Berndt et al., 2001; Wright et al., 2012)

7 Mid-Norwegian Volcanic Passive Margin... 1st need to write the introduction chapter

and then project can be extended on the effort

8

9 Introduction:

10 Large igneous province

Large igneous province (LIPs) show continuous volume of rock which is dominant in iron and

magnesium contents (mafic rock) and are form other than normal process like seafloor spreading.

On the basis of some properties like petrologic, geochemical, geochronological, geophysical, and

physical volcanological data, the productions of LIPs are easily identified from other two

important types of magmatism, i-e arc magmatism and mid-oceanic ridge magmatism. LIPs are

dominant on continent and oceanic crust including continental flood basalts, volcanic passive

margins, oceanic plateaus, submarine ridges, seamount chains, and ocean-basin flood shown in

figure 1 and table 1(Coffin and Eldholm, 2005)

11 2) Volcanic passive margins (VPM)

Volcanic passive margin (VPMs) are belong to large igneous provinces (LIPs), which comprise

the extensive volumes of intrusive and extrusive mafic rocks and dried1 out after the short period.

These passive margins can be associated with (Callot et al., 2002) ; (1) an abnormally thick

adjacent oceanic crust and (2) a hot spot track and tail, are related to lithospheric breakup over a

mantle plume [(Kelemen and Holbrook, 1995);(Eldholm et al., 1995)].

Volcanic passive margins have transitional narrow crust that forms as a result of continental

breakup and rifting over an anomalously hot mantle. Magmatism at VPM composed massively of

intruded continental crust which contains mostly flood-basalts and tuffs. These margins are

characterized by following three important features.(Callot et al., 2001)

1) Wedges shaped Strong Seaward dipping (lava flows) reflectors.

2) Central Intrusive structures together with dykes and swarms lateral to coast

3) Presence of high seismic velocity bodies (HVZ) at the lower crust resulted to magma under

plating.

-(خشک)1

11.1 Seaward dipping reflector:

Volcanic passive margins are quite different from non-volcanic passive margin mostly because of

diagnostic tectono-magmatic texture. These textures comprised enormous volume of magma

introduced during the early phase of seafloor spreading, normally as seaward dipping reflector and

various intrusive and extrusive bodies into sedimentary basin (Berndt et al., 2001). The high P-

wave velocity layer (Vp > 7 km/s) is observed below the extended continental crust near the

continent ocean transition (COT) and resulted to magma under plating from mafic to ultra-mafic

magma at the base of the crust (Lower crust) (Geoffroy, 2005). Recent study suggests that seaward

dipping

reflectors are distinguish feature to investigate the volcanic passive margin which show flood

basalt are extruded rapidly during the rifting or early development of seafloor spreading. The

seaward dipping reflectors indicate the offshore boundary limit of continental crust, thus can be

used to interpret the transitional boundary between continental and oceanic crust (COT) (pdf:

chapter 6 SDR)

figure1

The seaward reflectors display distinguishes appearance in the seismic reflection profile. Mutter

(1985) suggests following features of SDR sequence are consistent which are based on the

observation from multichannel seismic reflection profiles along the Norwegian continental

margin.

i) The reflector sequences dip ubiquitously seaward. At the landward limit of the sequences they

often assume a horizontal to near-horizontal attitude.

ii) The reflectors usually exhibit arcuate shapes indicating upward convexity.

iii) The reflectors diverge seaward and show an overall seaward offlap.

iv) The reflectors are distributed in the form of a sea-ward dipping wedge or

fan shaped configuration. The seaward limit of the wedges is seldom well

defined and shows no distinct basal reflector. (pdf: chapter 6 SDR)

11.2 Volcanic facies

High quality seismic data provides the ability to reinterpret old seismic data on the volcanic rifted

margins, it shows that the breakup of volcanism is common however it have considerably variation

in character and intensity along a margin and between margins. It is important to analyze structure

of the volcanism on rifted margin, it helps to get knowledge about the effect and causes of

continental breakup magmatism. It is difficult to interpret volcanic deposits by seismic reflection

data because of the heterogeneity.

The main component of seismic volcano stratigraphy is to analysis the seismic facies. Seismic

interpretation based on Improved multichannel seismic (MCS) reflection data along typical

volcanic rifted margin explain six characteristics of volcanic seismic facies given as:( 1) Landward

Flows,( 2) Lava Delta, (3) Inner Flows,( 4) Inner Seaward Dipping Reflectors( Inner SDR), (5)

Outer High, and( 6) Outer SDR (Planke et al., 2000). On the other hand it’s not always possible

to interpret all of these facies on a single margin. Further, note that we use our definition of the

seismic facies units when discussing previously published seismic data.

figure

2

Seismic facies are divided in tow part on the seismic profile landward and seaward of continental

ocean boundary. The landward part consists of three unit facies, The Landward Flow that have

sheet shaped seismic characteristic with parallel to subparallel seismic reflectors. The reflection

on top of this unit is strong and smooth. With the high quality MCS data can observe negative

reflection polarity on the basal boundary. Lava Delta is the second landward facies with internal

prograding reflection configuration. Its upper and lower boundary can interpret as toplap and

downlap surfaces. The third seismic landward facies is Inner Flow is a sheet shaped body with

wery disrupted or chaotic reflector. The top of the reflection has high amplitude and disrupted

event.

Inner SDR has fan shaped strong reflector. On the upper boundary its present as toplap and wedge

shaped. Between the Inner and Outer SDR, Outer High exists with mounded face and have chaotic

reflection configuration. The Outer SDR has the same characteristic as Inner SDR but located on

the outer part and the reflection ends on the Outer limit. Also this reflector have deeper depositional

environment on the seaward part of the profile. (Planke et al., 2000)

The explosive, shallow marine eruption stage forms the

characteristicm ounded Outer High and voluminousv olcaniclastics

edimentsa nd tuffs being depositedi n nearbyb asins.

The extensive tuff formation during this eruptive stage may

further be responsiblef or regional environmentacl hanges.

Resedimentationan d alterationo f the tuffs may yield smectire-

richc lay units with distinctp etrophysicaal nd geotechnical

properties. Voluminous deep marine sheet flow deposits

are further suggestedto be imaged as the Outer SDR, being

formed in a similar manner as the subaerial Inner SDR. The

deep marine nature of the Outer SDR unit is not constrained

by boreholed ata but is an easily accessibleta rget for scientific

drilling. (Planke et al., 2000) introductio 2 ra bekhon (2001_berndt_GeolSoc)

figure ..

12 Mid Norwegian Margin

The mid Norwegian margin is divided into three main parts, Møre, Vøring and Lofoten-

Vesterålen, ranging from 400 to 500km long. These margins are separated by East Jan

Mayen Fracture zone and Bivrost Lineament/transfer zone. Beneath these segment the

lower crustal body(LCB) are present and characterize with high P – wave velocity zone

(HVZ)between 7.3–7.6 km/s beneath the outer part of the mid – Norwegian volcanic

margin, due to the magmatic breakup.(Faleide et al., 2008; Geoffroy, 2005). Møre and

Vøring margin displays the best result of LCB beneath the marginal high.

The mid Norwegian margin are formed as a following tectono-magmatic

evolution(Eldholm et al., 2002): 1) The continental break up during the late Cretaceous-

Paleocene leading to lithospheric extension and rifting. 2) uplift

Figur 3 Mid Norwegian margin divided

into three main parts, Møre, Vøring and Lofoten-Vesterålen. JMR: Jan Mayen

Ridge, LVM: Lofoten-Vesterålen Margin, MM: Møre Margin, NSF: North Sea Fan,

SF: Storfjorden Fan, VM: Vøring Margin, VP: Vøring Plateau.

Vøring Margin, VP: Vøring Plateau,

13 Vøring Margin

The vøring margin is 500km wide and extended from southeast to northeast the Trøndelag

Platform, the Halten and Dønna terraces, the Vøring Basin and the Vøring Marginal

High. From Jurassic time the Trøndlag Platform is comparatively stable and contains

Triassic and Upper Paleozoic sediments filled deep basins. Deep MCS and Wide-angle

seismic refraction profiles construct Moho depth from 32 km near to mainland Norway and

25 km near to major parts of platform. The Vøring Basin is characterized by number of sub

basins and highs mostly displaying the differential vertical movements from Late Jurassic

to Early Cretaceous basin evolution((Faleide et al., 2008)).

The various researches on the vøring margin Performed by multichannel seismic reflection

data (Bøen et al., 1984; Skogseid and Eldholm, 1989; Brekke, 2000), seismic refraction

data (Eldholm and Mutter, 1986), commercial and experimental drilling on the continental

shelf and Vøring plateau (Spencer et al., 1984, 1986; Dalland et al., 1988), (Talwani et

al., 1976; Eldholm et al., 1987; Skogseid and Eldholm, 1989).

The lower crustal high velocity body mostly exists on the Vøring basin and Vøring plateau.

(However, the boundary between the Vøring and Lofoten–Vesterålen margins is important

as it coincides with a high-velocity lower-crustal body interpreted as the result of magmatic

underplating (Mjelde pers. comm. 2000). (2001_berndt_GeolSoc))These bodies normally

contain of mafic intrusion and mixed with blocks from the extended continental crust (e.g.,

Mjelde et al., 1997a). The velocity modeling shows large variation of velocity (7.1-7.8

km/s) and thickens (0-8 km) on the profile perpendicular and along margins. (Mjelde et al.,

2002)

Geological evolution of the Norwegian Margin:

This temperature anomaly is ascribed to the presence of the Icelandic mantle plume and

caused extensive melting of the upper mantle when the pressure on the upper mantle was

decreased during continental breakup (White & McKenzie 1989). The associated

magmatism resulted in intrusion of volcanic rocks into the sedimentary basins, magmatic

underplating

at the base of the crust, and large amounts of extrusive material (Hinz 1981; Mutter et al.

1982; Hinz et al. 1987; White & McKenzie 1989; Eldholm et al. 1989; Skogseid et al.

1992a; Eldholm & Grue 1994)

The breakup extrusive rocks have been the subject of several deep-sea drilling surveys:

DSDP Leg 38 and ODP Leg 104 on the Vøring Margin and ODP Legs 152 and 163 on

the southeast Greenland Margin. Shown that the breakup volcanic rocks have been

deposited during two phases of volcanism. The first consists of scattered basaltic, andesitic

and dacitic volcanism in a continental environment from 63 to 55.5 Ma. The second phase

during continental breakup lasted from 55.5 to 53 Ma.

The amount and distribution of the volcanic deposits on the Vøring Margin was the

subject of work by Hinz (1981),Mutter et al. (1982), Skogseid & Eldholm (1989), Skogseid

(1994), and

Eldholm & Grue (1994). Eldholm & Grue (1994) calculated that the flood basalts within

the North Atlantic Volcanic Province cover an area of 1.8 x106 km2.

(2001_berndt_GeolSoc))

Figure 4 Regional map showing the

Regional Setting and structural framework of different rift phases on the mid-

Norwegian margin. BL: Bivrost Lineament, EJMFZ: East Jan Mayen Fracture Zone,

JMR: Jan Mayen Ridge, MB: Møre Basin, MMH: Møre Marginal High, TP:

Trøndelag Platform, VB: Vøring Basin, VMH: Vøring Marginal High, WJMFZ:

West Jan Mayen Fracture Zone.

#

The Late Jurassic to Early Cretaceous extensional phase (ca. 150–130 Ma) led to major

faulting with reactivation of older fault zones, and generation of slightly rotated fault

blocks with subsequent subsidence along the major rift systems (Bøen et al., 1984;

Skogseid and Eldholm, 1989).

The maximum Early Cenozoic extension axis shifted westwards with respect to the Late

Jurassic- Early Cretaceous tectonic episode. The Late Cretaceous to Early Cenozoic

extension lasted 18–20 m.y., until continental break-up occured in Early Eocene.

During the syn-rift phase, the outer Vøring Margin was uplifted and exposed to erosion.

The late synrift period was associated with voluminous igneous activity, generating both

extrusives and intrusives into the adjacent sedimentary basin and emplacement of

magmatic material at the base of the crust (Mutter et al., 1984; Skogseid et al., 1992). The

extrusives

are partly manifested as wedges of seaward-dipping reflectors along the outer margin (e.g.,

Mutter et al., 1984).

The P-wave velocity within the lower crustal body varies significantly; from 7.1 km/s to

7.8 km/s. These variations can be explained by chemical differences in magma from gabbro

to ultramafic residuals (e.g., Holbrook et al., 1992), or to different degree of

serpentinization of peridotite (e.g., Christensen, 1982; Gebrande, 1982).

conclution

¤High P-wave velocities (7.1–7.7 km/s) and generally low Vp/Vs ratios (1.68–1.90) are

modelled for most of the lower crust on the Vøring Margin, in the area of the latest rifting

that led to continental break-up in Early Eocene.

The modelling results for the Vøring Plateau and the northern Vøring Basin are consistent

with a lower crust consisting of a mixture of mafic intrusions and older continental blocks,

but not with the presence of serpentinized peridotite.

In the central and southern Vøring Basin the same model is applicable, but the observations

of slightly higher Vp/Vs ratios implies that a model with a mixture of intrusions, continental

remnants and serpentinized periodotite cannot be ruled out based on the modelled seismic

velocities and densities.¤ (Mjelde et al., 2002)#

figure 5 Jan Mayen Fracture zone(Planke et al., 2000).

Vøring Margin profile located perpendicular to the margin strike across the Jan Mayen

Fracture zone. Note the presence of inner SDR the well-defined prograding reflection (r1)

in the lava Delta, and high amplitude disruptive reflection in the Inner Flows. FSE, Faeroe-

Shetland Escarpment; VE, Vøring Escarpment. T, top of volcanic sequence; p, planated

top-basement reflection.

Callot, J. P., Geoffroy, L., and Brun, J. P., 2002, Development of volcanic passive margins: Three‐

dimensional laboratory models: Tectonics, v. 21, no. 6, p. 2-1-2-13.

Callot, J. P., Grigné, C., Geoffroy, L., and Brun, J. P., 2001, Development of volcanic passive

margins: Two‐dimensional laboratory models: Tectonics, v. 20, no. 1, p. 148-159.

Eldholm, O., Skogseid, J., Planke, S., and Gladczenko, T. P., 1995, Volcanic margin concepts,

Rifted Ocean-Continent Boundaries, Springer, p. 1-16.

Faleide, J. I., Tsikalas, F., Breivik, A. J., Mjelde, R., Ritzmann, O., Engen, O., Wilson, J., and

Eldholm, O., 2008, Structure and evolution of the continental margin off Norway and the

Barents Sea: Episodes, v. 31, no. 1, p. 82-91.

Geoffroy, L., 2005, Volcanic passive margins: Comptes Rendus Geoscience, v. 337, no. 16, p.

1395-1408.

Kelemen, P. B., and Holbrook, W. S., 1995, Origin of thick, high‐velocity igneous crust along the

US East Coast Margin: Journal of Geophysical Research: Solid Earth (1978–2012), v. 100,

no. B6, p. 10077-10094.

Mjelde, R., Kasahara, J., Shimamura, H., Kamimura, A., Kanazawa, T., Kodaira, S., Raum, T.,

and Shiobara, H., 2002, Lower crustal seismic velocity-anomalies; magmatic underplating

or serpentinized peridotite? Evidence from the Vøring Margin, NE Atlantic: Marine

Geophysical Researches, v. 23, no. 2, p. 169-183.

Planke, S., Symonds, P. A., Alvestad, E., and Skogseid, J., 2000, Seismic volcanostratigraphy of

large-volume basaltic extrusive complexes on rifted margins: Journal of Geophysical

Research, v. 105, no. B8, p. 19335-19351.

14 North Atlantic Large Igneous Province (NAIP)

North Atlantic Large Igneous Province (NAIP) is associated with massive extrusive and intrusive

magmatism that appeared as a result of continental break up and sea floor spreading. These

magmatism normally are dominant by iron and magnesium contents (mafic rock). (Coffin and

Eldholm, 2005), (Coffin and Eldholm, 1994)

Volcanic passive margin (VPM) is belongs to large igneous provinces (LIPs), which comprise

transitional narrow crust that forms as a result of continental breakup and rifting over an

anomalously hot mantle. Magmatism activity at VPM are characterized by following three

important features.(Callot et al., 2001);

4) Wedges shaped Strong Seaward dipping (lava flows) reflectors.

5) Massive intrusion of sill and dyke into the sediments.

6) Mafic and ultra-mafic intrusion into the upper and middle continental crust (Abdelmalak

et al., 2015; Geoffroy et al., 2007; Karson and Brooks, 1999; Klausen and Larsen, 2002;

Lenoir et al., 2003; Meyer et al., 2009).

7) Presence of high seismic velocity bodies (HVZ) at the lower crust resulted to magma under

plating.

The crustal extension during the late Cretaceus lead to late Paleocene- Early Eocene seafloor

spreading in the Nord Atlantic (Meyer et al., 2007). Seafloor spreading and continental break up

during the Early Eocene caused enormous spreading of magmatism developing both extrusive and

intrusive complex structures along Norwegian margin.

. (Meyer et al., 2007).

Seismic refraction data shows the presence of high velocity lower crustal bodies at different

portion of the North Atlantic area (reef: voss, jokat holbrooh, mjelde….). These lower crustal

bodies have been identified as magmatic body along different segments at the North Atlantic

margins and the interpretation suggested that these bodies represent between (60 to 80%) of

magmatic volume in the NAIP`s (White et al. 1987, 2008; White & Smith 2009).

15 Mid Norwegian Margin

The mid Norwegian passive margin is belong to the North Atlantic Igneous Province and is the

one of the best studied volcanic margins.

The various researches on the mid Norwegian margin Performed by multichannel seismic

reflection data (Gernigon et al., 2003; Skogseid and Eldholm, 1989; Brekke et al., 2001;), seismic

refraction data ((Breivik et al., 2014; Faleide et al., 2010; Faleide et al., 2008; Mjelde et al., 2009b;

Mjelde et al., 2003; Talwani and Eldholm, 1972)), commercial and experimental drilling on the

continental shelf and Vøring plateau (Spencer et al., 1984, 1986; Dalland et al., 1988), (Talwani

et al., 1976; Eldholm et al., 1987; Skogseid and Eldholm, 1989).

The mid-Norwegian margin has a long history of episodic rifting, spanning between the

Carboniferous and Early Eocene break-up, a duration of approximately 250 Ma. During this long

period the extensional stress field rotated significantly, resulting in oblique overprinting of older

by younger rifts events (Fig. 2)(Lundin et al., 2013).

Mid Norwegian margin formed by various and continues extensional and rifting episodes that took

place in the Late Paleozoic- Early Triassic, Late Jurassic-Earl Cretaceous and Late Cretaceous-

Paleocene. The extension even during the Paleocene- Eocene led to the continental break-up of the

Nord Atlantic and also affected the magmatic activity on the Mid Norwegian margin(Gomez et

al., 2004) (Brekke, 2000; Eldholm and Grue, 1994; Faleide et al., 2010; Faleide et al., 2008); .

Mid Norwegian margin divided into three main margins, Møre, Vøring and Lofoten-

Vesterålen, which has the length range 400 to 500km (Faleide et al., 2008). These margins are

separated by East Jan Mayen Fracture zone and Bivrost Lineament/transfer zone. Also from

interpretation of potential field data? and seismic volcano stratigraphy, the distribution of extrusive

let us to divide the Møre, Vøring and Lofoten-Vesterålen into five more segment. The combination

of volcanic seismic facies unit shows the characteristic of typical rifted volcanic margin on the

central Møre Margin and the northern Vøring Margin. The Lofoten-Vesterålen, the southern

Vøring Margin and The area near the Jan Mayen Fracture Zone showing small volume submarine

seismic volcanic facieses(Berndt et al., 2001).

16 Vøring Margin

Vøring margin is a part of the Mid Norwegian Margin, Southwestern part of this margin is

separated by the East Jan Mayen Fracture (EJFZ), the Northeastern part by the Bivrost Lineament

(BL).

The structure of the vøring margin is about 500km wide and consisting of Trøndelag Platform, the

Halten and Dønna terraces, the Vøring Basin and the Vøring Marginal High from southeast to

northwest.

From Late Jurassic to Early Cretaceous Vøring Margin affected by crustal extension and thinning,

this led to subsidence and development of major Cretaceous basins. (Eldholm and Grue, 1994;

Faleide et al., 2008) (Blystad et al., 1995; Scheck-Wenderoth et al., 2007b; Skogseid et al., 2000).

By studding Wide-angle seismic refraction and deep MCS profiles, the Moho depth can be

estimated from (ca. 30-32 km) near to mainland Norway to 25 km on major parts of the platform.

The Vøring Basin is characterized by number of sub basins and highs mostly displaying the

differential vertical movements from Late Jurassic to Early Cretaceous basin evolution(Faleide et

al., 2008).

Pre-breakup basin evolution: The pre-opening, structural margin framework is dominated by the

NE Atlantic-Arctic Late Jurassic–Early Cretaceous rift episode responsible for the development

of major Cretaceous basins such as the Møre and Vøring basins off mid-Norway, and the deep

basins in the SW Barents Sea.

By mid-Cretaceous time, most of the structural relief within the Møre and Vøring

basins had been filled in and thick Upper Cretaceous strata, mainly fine-grained clastics were

deposited in wide basins.

Breakup-related tectonism and magmatism: Late Cretaceous–Paleocene rifting at the Vøring

Margin covers a ~150 km wide area bounded by the Fles Fault Complex and the Utgard High on

the east.

Final lithospheric breakup at the Norwegian margin occurred near the Paleocene–Eocene transition

at ~55–54 Ma (Chron 24r). It culminated in a 3–6 m.y. period of massive magmatic activity during

breakup and onset of early sea-floor spreading. At the outer margin (e.g., Møre and Vøring

margins), the lavas form characteristic SDR sequences that drilling has demonstrated to be

subaerially and/or neritically erupted basalts (Eldholm et al., 1989; Planke et al., 1999). These

seaward dipping reflectors have become diagnostic features of volcanic margins. During the main

igneous episode at the Paleocene–Eocene transition, sills intruded into the thick Cretaceous

successions throughout the NE Atlantic margin, including the Vøring and Møre basins.

Post-breakup margin evolution: Mid-Cenozoic compressional deformation (including domes/

anticlines, reverse faults, and broad-scale inversion) is well documented on the Vøring margin, but

its timing and significance are highly debated (Doré and Lundin, 1996; Vågnes et al., 1998;

Lundinand Doré, 2002; Løseth and Henriksen, 2005; Stoker et al., 2005a).

(Faleide et al., 2008)

The crust underneath Træna basin and westwards is thin ( _10 km), and the crust is roughly twice

as thick underneath the Trøndelag platform (Wangen et al., 2011).

fig..(Scheck-Wenderoth et

al., 2007a)

As part of the polyrifted system, the outer Vøring Basin was particularly affected by a Late

Cretaceous– Paleocene rifting leading to the breakup and seaward dipping reflectors emplacement

(Fig. ..)(Gernigon et al., 2004).

fig.. (Gernigon et al., 2004)

(Eldholm et al., 2002; Gernigon et al., 2003; Ren et al., 2003).

Berndt, C., Planke, S., Alvestad, E., Tsikalas, F., and Rasmussen, T., 2001, Seismic

volcanostratigraphy of the Norwegian Margin: constraints on tectonomagmatic break-up

processes: Journal of the Geological Society, v. 158, no. 3, p. 413-426.

Blystad, P., Brekke, H., Færseth, R. B., Larsen, B. T., Skogseid, J., and Tørudbakken, B., 1995,

Structural elements of the Norwegian continental shelf Part II: the Norwegian Sea Region:

NPD-Bulletin, The Norwegian Petroleum Directorate., v. 8.

Callot, J. P., Grigné, C., Geoffroy, L., and Brun, J. P., 2001, Development of volcanic passive

margins: Two‐dimensional laboratory models: Tectonics, v. 20, no. 1, p. 148-159.

Eldholm, O., and Grue, K., 1994, North Atlantic volcanic margins: dimensions and production

rates: Journal of Geophysical Research: Solid Earth (1978–2012), v. 99, no. B2, p. 2955-

2968.

Faleide, J. I., Tsikalas, F., Breivik, A. J., Mjelde, R., Ritzmann, O., Engen, O., Wilson, J., and

Eldholm, O., 2008, Structure and evolution of the continental margin off Norway and the

Barents Sea: Episodes, v. 31, no. 1, p. 82-91.

Gernigon, L., Ringenbach, J.-C., Planke, S., and Le Gall, B., 2004, Deep structures and breakup

along volcanic rifted margins: insights from integrated studies along the outer Vøring Basin

(Norway): Marine and Petroleum Geology, v. 21, no. 3, p. 363-372.

Gomez, M., Verges, J., Fernandez, M., Torne, M., Ayala, C., Wheeler, W., and Karpuz, R., 2004,

Extensional geometry of the Mid Norwegian Margin before Early Tertiary continental

breakup: Marine and petroleum geology, v. 21, no. 2, p. 177-194.

Lundin, E. R., Doré, A. G., Rønning, K., and Kyrkjebø, R., 2013, Repeated inversion and collapse

in the Late Cretaceous–Cenozoic northern Vøring Basin, offshore Norway: Petroleum

Geoscience, v. 19, no. 4, p. 329-341.

Scheck-Wenderoth, M., Raum, T., Faleide, J., Mjelde, R., and Horsfield, B., 2007a, The transition

from the continent to the ocean: a deeper view on the Norwegian margin: Journal of the

Geological Society, v. 164, no. 4, p. 855-868.

Scheck-Wenderoth, M., Raum, T., Faleide, J. I., Mjelde, R., and Horsfield, B., 2007b, The

transition from the continent to the ocean: a deeper view on the Norwegian margin: Journal

of the Geological Society, v. 164, no. 4, p. 855-868.

Skogseid, J., Planke, S., Faleide, J. I., Pedersen, T., Eldholm, O., and Neverdal, F., 2000, NE

Atlantic continental rifting and volcanic margin formation, in NOTTVEDT, A. e. a., ed.,

Dynamics of the Norwegian Margin, Volume 167: London, Geological Society, London,

Special Publications, p. 295-326.

Wangen, M., Mjelde, R., and Faleide, J. I., 2011, The extension of the Vøring margin (NE Atlantic)

in case of different degrees of magmatic underplating: Basin Research, v. 23, no. 1, p. 83-

100.