BASIN ARCHITECTURE AND LITHOSPHERIC STRUCTURE ... og kyst/Sokkel/Material/AGU09...2000 Admirality...
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BASIN ARCHITECTURE AND LITHOSPHERIC STRUCTURE OF THE BARENTS SEA REGION FROM GEOPHYSICAL MODELLING
L. Marello (1,2); J. Ebbing (1,2); L. Gernigon (1)1 Geological Survey of Norway (NGU), Trondheim. 2 Department for Petroleum Engineering and Applied Geophysics,
Norwegian University of Science and Technology (NTNU), Trondheim.
Part of:PETROBAR Project
“Petroleum-related regional studies of the Barents Sea region" project funded by NFR and Statoil and includes participants from the University of Oslo, PGP, University of Bergen, International Re-search Institute of Stavanger, Geological Survey of Norway and Volcanic Basin Petroleum Re-search.
Contact: [email protected]
NGUNorges geologiske undersøkelseGeological Survay of Norway
Magnetic model made by 6 layers with homogeneous properties
Magnetic Basement blocks and geological implica-
Svalbard : Magnetic lineaments are correlating with Caledonian structures
West Barents Sea: anomaly trends represent Caledonian Thrust Front
West Barents Sea: high magnetic block; high pseudogravity; shallowing of deep dense lowercrust could be a methamorphic core complex formed during the exumation of the lower crustalrocks by low-angle detachments
Central Barents Sea High Anomalies:seems to be part of two different basement blocks
E-Svalbar : Sill intrusions are related to the CretaceusMagmatic event
NE-Barents Sea : pseudogravity coincident with Bouguer gravity
Central-N Novaya Zemlya : susceptibility inversion and forward modelling not coinciding
N and S East Barents Sea Basin:have different basement
SW Barents Sea: Magnetic block: Early Proterozoic and Archeancomplexes are near the surfaceNon Magnetic block: thick turbidite succession
SW Barents Sea: Anomaly trends coincide with Timanian trends
S Novaya Zemlya : Anomaly trends coincide with Timaniantrends
E-Svalbard : Small scale anomalies have shallower Euler solutions and are considered the effect of sill intrusion
NE-Barents Sea 1:Lineaments are following Uralian setting
4) INTEGRATION OF RESULTS
Fendinsky High: lineaments seems to be the prolongations of Timanian linea-ments (e.g. BF: Baidaratsky Fault)
The magnetic field analysis and the in-version results combined with the for-ward models give a regional overview of the Barents Sea basement and allow to organize the area in sub-domains with similar magnetic properties.The magnetic patterns in comparison with geological trends and the suscepti-bility distribution help to illustrate the tectonic setting.
Bibliography- Blakely, R., 1995. Potential Theory in Gravity and Magnetic Applications. Cambridge University Press. , 461 pp.-Dimakis, P., Braathen, B.I., Faleide, J.I., Elverhoi, A. and Gudlaugsson, S.T., 1998. Cenozoic erosion and the preglacial uplift of the Svalbard-Barents Sea region. Tectonophysics, 300(1-4): 311-327.- Grad, M., Tiira, T. and Group, E.W., 2009. The Moho depth map of the European Plate. Geophys. J. Int., 176,(279-292).- Gramberg, I.S., Glebovsky, V.Y., Grikurov, G.E., Ivanov, V.L., Korago, E.A., Kos'ko, M.K., Maschenkov, S.P., Piskarev, A.L., Pogrebitsky, Y.E., Shipelkevitch, Y.V. and Suprunenko, O.I., 2001. Eurasian Arctic Margin: Earth Science Problems and Research Challenges. Polarforschung, 69: 3-25.-Jakobsson, M., Macnab, R., Mayer, L., Anderson, R., Edwards, M., Hatzky, J., Schenke, H.W. and Johnson, P., 2008. An improved bathymetric portrayal of the Arctic Ocean: Implications for ocean modeling and geological, geophysical and oceanographic analyses. Geophysical Research Letters, DOI: doi: 10.1029/2008gl033520.- Johansen, S.E., Ostisty, B.K., Birkeland, Ø., Fedorovsky, Y.F., Martirosjan, V.N., Christensen, O.B., Cheredeev, S.I., Ignatenko, E.A. and Margulis, L.S., 1992. Hydrocarbon potential in the Barents Sea region: play distribution and potential. In: T.O. Vorren et al. (Editors), Arctic Geology and Petroleum Potential. Norwegian Petroleum Society (NPF), Special Publication, pp. 273-320.- Ritzmann, O., Maercklin, N., Faleide, J.I., Bungum, H., Mooney, W.D. and Detweiler, S.T., 2007. A three-dimensional geophysical model of the crust in the Barents Sea region: Model construction and basement characteriza-tion. Geophysical Journal International, 170(1): 417-435.- Skilbrei, J.R., 1991. Interpretation of Depth to the Magnetic Basement in the Northern Barents Sea (South of Svalbard). Tectonophysics, 200 (1-3): 127-141
4 transects FORWARD MODELLING
To validate the inversion results, to test the susceptibility distribu-tion and to refine the top basement geometry we apply forward modelling.The seismic models reflect the main structures and constrain the geometry.Density modelling provides extra constraints for the deep struc-tures (e.g. Moho). The results of the susceptibility inversion have been used to set the average susceptibility on the initial magnetic domains.After large number of tests the initial magnetics, densities and crustal geometries were jointly refined.The results along the WE lines are integrated and combined using the SNBS.
Error= 2.2927
= Calculated= Observed,
Grav
ity (m
Gal)
-10
0
10
20
Mag
netic
s (nT
)
-100
0
100
200
300
Dept
h (k
m)
40
30
20
10
0
0 400 800 1200Distance (km)
0.0032700
0.0032500
Cenozoic/Mesozoic sediments
Paleozoic sedimentsPaleozoic/Riphean complex
Finmark Platform
Central Barents
Monocine Tiddlybanken
BasinFedynskiy
High
North East Barents
Sea BasinKola-KaninMonocline
MaliginskiyGraben
Paleozoic/Riphean complex
0.0082760
0.0182760
0.0132730 0.04
2910
0.0352810 0.079
27900.0522880
0.0212850
0.0272800
0.0292720
0.0232710
0.00013290
Error=35.34
= Calculated= Observed,
Mantle
0.0053020
0.0053020
0.0053000
SBS
line
CBS
line
NBS
line
D1 D2 D3
BasmABasmB
Susceptibility SIDensity kg/m3
SNBS line
0.0022810
0.012840 0.035
2950
0.0272830
0.01628500.027
2750
0.003 ?2810|
0.0032700
0.0013060
0.0013110
0.0013000
0.019 ?2770
0.0012500
Cenozoic/Mesozoic sediments
Paleozoic sediments
Grav
ity (m
Gal)
0
50
100
Mag
netic
s (nT
)
-100
0
100
200
Dept
h (k
m)
40
30
20
10
0
500 1000 1500Distance (km)
Error= 50.149
= Calculated= Observed,
Error= 15.142
= Calculated= Observed,
0.0032760
0.0092890
02700
02800
0.0042830
02500
0.00063290 Mantle
NO DATANO DATA
BasmABasmB
Bille�ordenFault Zone
Norwegian Greenland Sea
Svalbard Margin
Franz Victoria Basin
Kong KarlsPlatform
North East Barents Sea Basin
Skalistoe Uplift
C1 C2 C3 C4 C5
NSBS
line
Susceptibility SIDensity kg/m3
NBS line
D=2700, S=0.006
0.0053040
0.0053010
0.0182820
0.0312850 0.014
28400.0112930
0.0192820
0.0272820
0.0013290
Mantle
027500.022
2880
0.0152780
0.0272730
0.0012500
Central Barents Sea Monocline
Kong KarlsPlatform
OlgaBasin
SørdkappBasin
EdgeøyaPlatrdorm
Norwegian Greenland Sea
Cenozoic/Mesozoic sediments
Paleozoic sediments 0.003, 2700
Error= 10.606
= Calculated= Observed,
NavayaZamlya
0 500 1000 1500
SNBS
line
Distance (km)
0
-30
30
60
0
10
20
30
40
Error= 35.631
= Calculated= Observed,
Dep
th (K
m)
Gra
vity
(mG
al)
Mag
netic
s (n
T)
50
-80
80
0
0.0052000
AdmiralityHigh Kara Sea
BasmABasmB
Noth-East Barents Sea Basin
B1 B2 B3 B4
Susceptibility SIDensity kg/m3
CBS line
Dep
th (K
m)
Gra
vity
(mG
al)
Mag
neti
cs (n
T)
0.0452710 0.046
2720
0.062940
0.042780
0.0012450
0.0262750
0.0482980
0.0142770
0.0013290
Mantle
0.0052930
0.0342810 0.027
2850
02740
0.0242730
0.0012500
Central Barents Sea High
S-East Barents Sea Basin
NavayaZemlya
NordkappBasin
OttarBasin
NorselHigh
SvalisDome
BjørnyaBasin
StappenHigh
VastbakkenVolcanicProvince
SNBS
line0 400 800 1200
0
10
20
30
40
0
-30
30
60
-100
0
100
200
Distance (km)
Error= 6.662
Error= 39.625
= Calculated= Observed,
= Calculated= Observed,
Cenozoic/Mesozoic sediments
Paleozoic sediments 0.002, 2700
A1 A2 A3 A4
BasmABasmB
Susceptibility SIDensity kg/m3
SBS line
2) MAGNETIC BASEMENT STUDY FROM INVERSION
Layers Susceptibility (SI*10-3) Boundaries layer0 km constant grid
1-Water 0Bathymetry1
2-Upper sediments 0.314 8 km constant grid
3-Lower sediments 2.51 Top basement2
4-Upper crust 12.57-37.7 25 km constant grid
5-Lower crust 5.03Moho 3
6-Mantle 0.6283
3) BASEMENT STUDY FROM COMBINED FORWARD MODELLING
NGU-VESEGEI compilation 2009
H ig h p a s s m a g n e tic fie ld L o w p a s s m a g n e tic fie ld
T ilt d e riva tive m a g n e tic fie ld P s e u d ogra vity
High pass 70 km trendsHigh pass 120 km trendsTilt derivative trends
On the map the picks of the filtering and tilt derivatives are displayed. The pseu-dogravity in the background helps to define the magnetic anomaly regions.
MAGNETIC FIELD ANALYSIS
Anomalies enhancement
3D INVERSION TECHNIQUE
3D Euler solutions
Shallower solutions :1-Kola kanin Monocline extending northward up to the Nordkapp Basin2- Eastern part of Svalbard
Medium solutions1- Central North Barents Sea
Deep solutions:1- Noethwest of Admirallity Highand Myszheniya Highs2- southern part of the South East Barents Sea3- two central Barents Sea anomalies
SI= 0.5 Thick step
4 . 18 8 .38 12.6 17 .8 23 28 .3 33 .5 3 8 . 7 SI x 10-3
HM
HM
LM
HM
MM
MM
LM
HMMM
HM LM
LM
MM HM
LM HM
HM HM
MM
LM
HM
LM HM MMHM
LM MM HMHM
NBS line
CBS line
SBS lineSNBS line
a)
b)
c)
d)
e)
NBS
CBS
SBS
SNBS
Sensitivity test Influence onsusceptibility results
Top basement uncertainty depths max8kmshallower
-3,8 SI*10-3
Top basement uncertainty depths max6 km deeper
6 SI*10-3
Low pass filtered magnetic field -2,5 – 2,5 SI*10-3
Upper continued magnetic field -5,6 – 5 SI*10-3
All basement magnetic -7,5 – 5 SI*10-3
Uncertainty ≈ 30%
3D INVERSION TECHNIQUE
inversion tests
SUSCEPTIBILITY INVERSIONMAGNETIC RESIDUAL
1=IBCAO model (Jakobsson et al., 2008); 2=W-Barents Sea (Skjlbrei et al. 1991); E-Barents Sea (Johansen at al., 1992: Gramberg et al., 2001); 3=combination of Barents 50 (Ritzmann et al., 2007) and Moho depth of the European Plate (Grad et al., 2009)
SENSITIVITY TEST
First regional indication of the mag-netization distribution in the Barents
Sea basement.
Low Magneticbasement
Medium Magneticbasement
High Magneticbasement
Magnetic Map Anomaly
Magnetic anomaly regions defined from field analysis.
Parameters used for the susceptibility inversion:
- Total magnetic field-inverted layer (upper crust) simpliffied as the sum of vertical prisms of
infinite depth extension.-Inversion routine for basement: combination of filters and inverse Earth
filter (Blakley, 1995)-Starting susceptibility: 0.031 SI
-Maximum standard deviation= 10 nT-Maximum number of iterations= 9
-No changes in geometries
Forward modelling results:
- give reasonable explanation of magnetic and gravity anomalies- are consistent with the inversion results- refine the magnetic basement
++++ Observed magnetic anomaly++++ Calculated magnetic anomaly
W E
W E
W ES N
T33A-1867
Dimakis at al. 1998
Density-depth relation
1) Linear function 2) Exponential function
Petrophysical database(density and susceptibility)
Velocity / density relation
Structural maps
1) EXISTING DATA Seismic informations
Moho depths from BARENTS50 modelhttp://www.norsar.no/c-90-Barents-Sea-3D-Model.aspx
Top Basement models
The uplift and the con-sequent emersion and erosion of the West Bar-ents Sea have implica-tion in the physical property distribution.
BasmA: form Skilbrei et al., 1991 (West Barents Sea) and Johansen et al., 1992 (East Barents Sea).BasmB: from Skilbrei et al., 1991 (West Barents Sea) and Gramberg et al., 2001 (East Barents Sea).
Contour lines every 2.5 km.
The Barents Sea tectonic setting is the result of multiple tectonic processes including three orogenic phases (Timanian, Caledonian and Uralian) and several episodes of rifting leading to a complex tectonic setting. Most prominently this can be observed in the differences between the rift basins configuration of the West Barents Sea and the mega-sag basins of the Eastern Barents Sea. The mechanisms leading to the present day basin and crustal architecture are still not completely understood.
In the present study we investigate the top basement geometry and the basement properties of the Barents Sea by testing the validity of previ-ous studies and trying to overcome the discrepancies between them. To reach our interest beside the conventional magnetic field analysis, we run inversion magnetic modelling and sensitivity tests. The inversion re-sults are then integrated along four profiles with seismic and gravity data and using 2D combined forward modelling we refine the magnetic properties along the profiles. The four lines are linked together and illus-trate the main crustal units of the all Barents Sea associated as different magnetic basement domains. Finally we discuss the meaning of the magnetic anomalies and of our results in terms of tectonic and geologi-cal implications.
Neog
ene
Pale
ogen
eCr
etac
eous
Jura
ssic
Tria
ssic
Perm
ian
Carb
onife
rous
Devo
nian
Silu
rian
Ord
ovici
anCa
mb-
rian
MES
OZO
ICPA
LEO
ZOIC
rifting (N. Atlantic, Arctic, W. Siberia)
episodic rifting episodes
Verkhoyansk orogenyEast Siberia
uplift-erosion in Arctic areas
Initiation of EurekanOrogeny
N. Atlantic riftingleading to breakup
BREAKUP EURAMERICAN BASIN
BREAKUP N. ATLANTIC
carbonate platformorganic buildups
evaporites
progressive closure ofthe Iapetus
CollisionBaltica-Greenland(Scandian Orogen)
Post-orogenic collapse
GEODYNAMIC EVENTS
TERT
IARY
Q u a te rn a ry
widespreadintracratonic
rifting
Uralideorogeny
Ellesmerian/Caledonian
orogeny
Iapetus formation
major plate reorganisation
Siberiantrapps
renewed uplift and erosionof Ural orogen
transtensionnal and transpressive regimes along the Western Barents shelf
humid climate affects sedimentation
Boreal and Thetys oceans disconnected
Pale
o-pr
oter
ozoi
c
PRO
TERO
ZOIC
Mes
o-pr
oter
ozoi
cNe
o-pr
oter
ozoi
c
Timanianorogeny
INTRODUCTION