Tectonic structure and evolution of the Alpha-Mendeleev Fracture Zone Chernykh A.1,2, Glebovsky V.1., Korneva M.1, Astafurova E. 1, Redko A.G. 1 I.S. Gramberg VNIIOkeangeologia (VNIIO), St.-Petersburg, Russia 2 Saint Petersburg State University, Russia
e-mail:
[email protected] 35th IGC Cape Town, Republic of South Africa 2016
Study Area Depth, m
Main structures:
Ellesmere I.
Eurasian Basin (EB)
North Pole
EB
Amerasia Basin LR
MB
CAM
AR
PB
MeB
MR
MR CaB ESM
Alpha Ridge (AR) Mendeleev Ridge (MR) Chukchi Borderland (CB) Canadian Basin (CaB) Makarov Basin (MB) Mendeleev Basin (MeB) Podvodnikov Basin (PB)
CB
Banks I.
East-Siberian continental margin (ESM) Canadian Arctic continental margin (CAM) Fig. Bathymetry of the Amerasia Basin (IBCAO v.3.0 (Jakobsson et al., 2012)
Alpha-Mendeleev Ridges Transition LR
Sotrudnichestva (Cooperation) Gap [Treshnikov et al., 1967]
AR
N
MR
Fig. Bathymetry of the AlphaMendeleev transitional zone (IBCAO v.3.0 (Jakobsson et al., 2012) «The angular relationship between the Mendeleyev Ridge and the Alpha Cordillera appears to result from a southerly displacement of the cordillera crest along numerous an echelon transform faults» (Hall, 1970)
Research results overview EGU Conference 2014 Chernykh A.A., Astafurova E.G., Korneva M.S., Egorova A.V., Redko A.G., Glebovsky V.Yu. Tectonic pattern of the Mendeleev Ridge and adjacent basins: results of joint analysis of potential fields and recent Russian seismic data // Geophysical Research Abstracts, Vol. 16, EGU2014-14872, 2014 Publication Chernykh A. A., Astafurova E. G., Glebovsky V. Yu., Korneva M. S., Egorova A.V., Redko A. G. New data on the tectonics of the Mendeleev Ridge and adjacent geological structures // Doklady Earth Sciences, 2016, 470, 2, pp. ICAM-7 Conference 2015 Chernykh A. A., Glebovsky V. Yu., Egorova A. V., Redko A. G., Sukhanov R. A. Tectonic structure and evolution of the Alpha-Mendeleev Fracture Zone // Abstracts of the International Conference on Arctic Margins VII, 2–5 June 2015, Trondheim, Norway. IGC-2016
Bathymetry & Potential Fields
N
+ -
Bathymetry model IBCAO v.3.0 [Jakobsson et al., 2012]
• • •
Magnetic anomaly map [Glebovsky et al., 2012]
Free air anomaly map [Glebovsky et al., 2012]
Specific magnetic anomaly field -> HALIP –High Arctic Large Igneous Province Chaotic, irregular character of AMF [ex., Grantz et al., 2011] Actually - boundaries of geostructures, their internal peculiarities, tectonic elements - could be distinguished
Potential Fields Interpretation • Correlation between magnetic, gravity anomalies and relief of basement is existed • Horst/graben structures are clearly seen on seismic sections across and along the Mendeleev and Alpha Ridges Dg Calculated
Dg Observed
(DT)a Observed Alpha Ridge
upper crust
low crust
mantle
Fig. Gravitational model along MR. Upper part is based on MCS data from «Arktika-2012»
Mendeleev Ridge tectonic structure • Horst-graben structure • MR • South part – N-S orientation • North part – NW-SE orientation, rhomboid form
Thickness, km
Boundaries of geostructures
• AR • NE-SW orientation Faults
Strike-slip & oblique-slip faults
Grabens, half-grabens
Fig. The structural and tectonic scheme of MR and adjacent geostructures
Slip Faults & AMFZ • Strike-slip & oblique-slip faults: • found by offsets of anomalies and by rhomboid grabens joining in pull-apart basins; • are sinistral faults; • supported by multichannel seismic data (next slides); • point to existed transtensional conditions; • form broad Alpha-Mendeleev Fracture Zone (AMFZ).
Fig. Alpha-Mendeleev Fracture Zone (AMFZ) location between MR and AR
Thickness, km
Multichannel Seismic Data S
N
0
V.E. 1:3
S
0
5 km
Line 1201
Flower structure
25 km
N
Multichannel Seismic Data
• Results of Interpretation of reflection seismic data crossing Alpha-Mendeleev Fracture Zone (AMFZ) had supported it existence
Tectonic Structure of Study Region
Bathymetry, meters
• The draft tectonic scheme of Arctic Ocean is shown with other shear zones proposed
Fig. The draft tectonic scheme of whole study region over the map of bathymetry IBCAO 3.0 [Jakobsson et al., 2012]
ARCTIDA? •
Moving back the blocks of Mendeleev Ridge and Chukchi Borderland along AMFZ finally led to idea of initial unity of all blocks with present thick crust (>22 km) in Amerasia Basin (AR, MR, LR, CB, etc.)
•
They are seemed to be blocks of continental Arctida [Zonenshain, Natapov, 1987]
Makarov Basin
AR
Podvodnikov Basin
Mendeleev Basin
MR
Canadian Basin
CB
ES (De Long High)
Fig. Reconstruction of strike-slip motion of the Mendeleev Ridge and Chukchi Borderland along AMFZ back in time shown over map of consolidated crust thickness
North Chukchi Basin
Crust thickness, km less
10.4
12.0
13.7
15.4
17.1
18.8 20.5
22.2
23.9
25.5
27.2
28.9 30.6
32.3
34.0
35.7
more
Evolution ~155 Ma • Existence of ARCTIDA (Zonenshain, Natapov, 1987) • Beginning of Canada Basin (CB) opening
Arctic Canada
AR
MR
CB
CB – Chukchi Borderland; AR –Alpha Ridge; MR – Mendeleev Ridge
The Legend spreading continental rifting
Alas ka
shear zones HALIP carapace
Evolution ~130 Ma • HALIP emplacement (138-125 Ma by Dossing et al., 2012) • Phase 2 of Canada Basin opening (Grantz et al., 2011) • Beginning of disintegration of AR+MR+CB blocks
AR
MR
t-Sib
Arctic Canada
Eas erian
CB
-Chu kchi
CaB
f sh e l
CB – Chukchi Borderland; Cab - Canada Basin; AR –Alpha Ridge; MR – Mendeleev Ridge
The Legend spreading continental rifting
shear zones Alaska
HALIP carapace
Evolution
lf she a r - Ka nts
AR
PB
Arctic Canada
e Bar
~110 Ma • Rifting/spreading in Mendeleev and Podvodnikov Basins • AMFZ functioning (125 -100 Ma, this study) • Rifting in Makarov Basin
MeB
East-Siberian-Chukchi shelf
MR
CaB
CB
Alaska
AMFZ – AlphaMendeleev Fracture Zone; CB – Chukchi Borderland; CaB - Canada Basin; AR –Alpha Ridge; MeB – Mendeleev Basin MR – Mendeleev Ridge PB – Podvodnikov Basin
The Legend spreading continental rifting
shear zones HALIP carapace
Evolution ~90 Ma • End of rifting/spreading in Podvodnikov & Makarov Basins ara ts-K n e Bar
lf she MB
PB
East-Siberian-Chukchi shelf
Arctic Canada
AR
MeB MR
CaB
CB
CB – Chukchi Borderland CaB - Canada Basin AR –Alpha Ridge MB – Makarov Basin MeB – Mendeleev Basin MR – Mendeleev Ridge PB – Podvodnikov Basin
The Legend spreading continental rifting
shear zones HALIP carapace
Alaska
Evolution Greenland
en Ba r
~70 Ma • Onset of rifting in the Barents-Kara shelf (Drachev et al., 2011)
lf she a r a ts-K LR MB AR
East-Siberian-Chukchi shelf
Arctic Canada
PB
MeB MR
CaB
CB
Alaska
CB – Chukchi Borderland CaB - Canada Basin AR –Alpha Ridge LR – Lomonosov Ridge MB – Makarov Basin MeB – Mendeleev Basin MR – Mendeleev Ridge PB – Podvodnikov Basin
The Legend spreading continental rifting
shear zones HALIP carapace
Evolution Greenland
Present time • Spreading in Eurasian Basin
EB LR MB AR
East-Siberian-Chukchi shelf
Arctic Canada
PB
MeB MR
CaB
CB
Alaska
CB – Chukchi Borderland CaB - Canada Basin AR –Alpha Ridge LR – Lomonosov Ridge MB – Makarov Basin MeB – Mendeleev Basin MR – Mendeleev Ridge PB – Podvodnikov Basin
The Legend spreading continental rifting
shear zones HALIP carapace
General Conclusions AMFZ – is broad shear zone between Alpha and Mendeleev Ridges comprising system of sinistral strike-slip and oblique-slip faults formed in transtensional conditions AMFZ – is key geological structure to reveal tectonic evolution of the Amerasia Basin AMFZ was functioning while formation of the Mendeleev Basin due to extension which came from the opening Canada Basin (during Phase 2), in time period of ~125-100 Ma
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