\documentclass[twoside]{article}
\usepackage[silent,pdf,hyper]{elxshort}
\usepackage{color}
\usepackage{hyperref}
\journalid{ES}{19}{1}{19}
\citnumber{}{4}
\paperid{2018ES000652}
\papertype{RAR}
\cpright{}{2019}
\lefthead{artyushkov and chekhovich}
\righthead{geodynamics of the lomonosov ridge} % in the Central Arctic
\received{6}{December}{2018}
\accepted{18}{December}{2018}
\published{5}{February}{2019}
\definecolor{brown}{RGB}{157,23,4}

\authaddr{Peter Chekhovich, Earth Science Museum, Moscow, Russia.
 (p.chekhovich@gmail.com)}


\begin{document}

\title{Geodynamics of the Lomonosov Ridge in the Central Arctic}

\author{1}{Artyushkov}{E. V.}{}{1}{}{}
\author{2}{Chekhovich}{P. A.}{}{1}{2}{}

\affil{1}{Schmidt Institute of Physics of the Earth of the  RAS}{Moscow}{}{Russia}
\affil{2}{Lomonosov Moscow State University, Earth Science Museum}{Moscow}{}{Russia}

\keywd{Arctic region}
\keywd{Cenozoic}
\keywd{gravity and isostasy}
\keywd{lithospheric flexure}
\keywd{continental crust}
\keywd{lithosphere}
\keywd{role of fluids}
%Geodynamics of the Lomonosov Ridge in the Central Arctic
%E.V. Artyushkov , P.A. Chekhovich1,
%  Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS)
%  Lomonosov Moscow State University, Earth Science Museum
%  KEYWORDS: Arctic region; Cenozoic; gravity and isostasy; lithospheric flexure; continental crust; lithosphere; role of fluids.


\abstract{The deep-water basin on the Lomonosov Ridge in Central Arctic was rapidly
formed on a shallow water shelf in the early Miocene. The continuity of the main
seismic reflectors in the sedimentary cover of the ridge indicates no significant
crustal stretching during the subsidence. The absence of large free-air gravity
anomalies above the ridge precludes the dynamic topography in the mantle from
being a cause of the formation of the basin. In the Miocene, the ridge was very far
from the convergent boundaries therefore lithospheric flexing is unlikely to
produce the subsidence. Under these conditions, crustal subsidence on the ridge was most probably associated with the increase in the crustal density due to
metamorphic reactions catalyzed by fluid infiltration from the mantle.}


\section{Introduction}
\vspace*{0.85\baselineskip}

\begin{sloppypar}
     The Central Arctic
(\figref{1})           % (Fig.1)
     is characterized by deep water conditions. The
Eurasian Basin is underlain by the oceanic crust. It was formed by sea-floor
spreading on the Gakkel Ridge during the last 53 Myr. The nature of the crust in
the \mbox{1--4-km-deep} Amerasian Basin is debatable. Most researchers relate it to the
oceanic type, probably modified by magmatic intrusions and underplating
[\itc{D{\o}ssing et al.,} \reflink{Doss17}{2017};
\itc{Grantz et al.,} \reflink{Gran11}{2011};
\itc{Lawver et al.,} \reflink{Lawv02}{2002}
and many others].
However,
band magnetic anomalies formed by sea-floor spreading are absent in this region.
Hence, it is believed that the oceanic crust was formed during the Cretaceous
Normal Superchron 83--125 million years ago
[\itc{Olson and Amit,} \reflink{Olso15}{2015}]
when the
Earth's magnetic field had normal polarity.
\end{sloppypar}

\begin{sloppypar}
Deep seismic refraction profiling shows that a \mbox{1-5-km-thick} layer with P-wave
      velocities typical of the granitic layer of the continental crust exists in the
upper crust of the Amerasian Basin
[\itc{Kashubin et al.,} \reflink{Kash13}{2013}].
 Based on these data
many Russian authors believe that the basin is underlain by the continental crust
(see
[\itc{Piskarev et al.,} \reflink{Pisk16}{2016}]
for review). In this case, the question arises, what could
have caused a strong crustal subsidence with the formation of deep-water basins on
the continental crust which was initially above sea level or close to it. The lack of
direct data regarding the history of crustal subsidence in the Amerasian Basin is the
main problem.
\end{sloppypar}

\begin{figure*}                     % Fig 1
\figurewidth{35pc}
\setimage{}{}{27pc}{}{2018es000652-f01}
\caption{Deep-water provinces of the Central Arctic. Location of the deep-sea
drilling site is shown by red dot. Bathymetry visualizations based on the
GEBCO$\_$2014 grid.
\href{https://www.gebco.net/data_and_products/imagery/documents/gebco_2014_arctic_ocean.pdf}{https://www.gebco.net/data\_and\_products/imagery/documents/gebco\_2014\_arctic\_oce an.pdf}.}
%%\end{figure*}
\vspace*{.5\baselineskip}
%%\begin{figure*}                    % Fig 2
%%\figurewidth{35pc}
\setimage{}{}{35pc}{}{2018es000652-f02}
\crosscaption{Four boreholes and composite section of the Cretaceous sediments
on the Lomonosov Ridge (modified after
[\itc{Moran et al.,} \reflink{Mora06}{2006}]).}
\end{figure*}


     Deep-sea drilling in the Central Arctic was carried out only in the axial part
of the Lomonosov Ridge close to the North Pole
(\figref{2}).           % (Fig. 2).
The water depth in this
region is about 1000~m
[\itc{Backman et al.,} \reflink{Back06}{2006};
\itc{Moran et al.,} \reflink{Mora06}{2006}].
 Four holes
were drilled
(\figref{2}),           % (Fig. 2),
which allowed the compilation of a composite 428-m-long
geological section. A regional seismic unconformity (shown in yellow) separates
the Cenozoic sedimentary cover from the underlying Cretaceous continental crust.

\section{Basin Evolution}

\begin{figure}[t]                     % Fig 3
\figurewidth{20pc}
\setimage{}{-1.3ex}{20pc}{}{2018es000652-f03}
\bottomcaption{Sediment thickness in the axial part of the Lomonosov Ridge versus
the duration of the deposition (modified after
[\itc{Jakobsson et al.,} \reflink{Jako07}{2007}];
 m.c.d. -- meters composite depth).}
\end{figure}

     The drilling data obtained on the Lomonosov Ridge allow us to reconstruct
the history of crustal movements on the ridge during the Cenozoic and latest
Cretaceous. The part of the composite section with the thickness about 200~m
includes the Paleocene and lower Eocene sediments which were deposited in the
brackish-water estuarine environment
(\figref{3}).           % (Fig. 3).
The middle Eocene and Oligocene
sediments are absent which produces a 26-Myr long non-depositional hiatus and
regional unconformity (RU) in the seismic section
[\itc{Poselov et al.,} \reflink{Pose14}{2014}].
 This non-deposition
epoch ended in the early Miocene 18.2~Myr ago. The hiatuses with the
absence of sediments alternating with the episodes of shallow-water deposition
also occur in the lower part of the composite section
 [\itc{Backman et al.,} \reflink{Back08}{2008}].
 There
are a few meters of Upper Cretaceous terrestrial deposits at the base of the
composite sedimentary section. These deposits are of the late Campanian or
probably Maastrichtian age. About 72.5~Myr ago, the so-called \mbox{Post-Campanian}
unconformity (pCU) was formed at their top. These data indicate that the crust
surface of the Lomonosov Ridge remained close to sea level for at least 54~Myr.

     A drastic change in the deposition on the ridge occurred in the early
Miocene 18.2 Myr ago. Regional unconformity RU was overlain by the pelagic
sediments whose deposition has continued up to present
(\figref{3}).           % (Fig. 3).
This suggests
rapid subsidence of the crust with the formation of a deep-water basin. As follows
from the seismic reflection data, the subsidence occurred all across the ridge (see,
e.g.,
\figref{4}).           % Fig. 4).
 Its magnitude is about 1~km on the ridge axis and up to 2--2.5~km on
the ridge's margins.

\begin{figure*}[t]                     % Fig 4
\figurewidth{35pc}
\setimage{}{}{35pc}{}{2018es000652-f04}
\crosscaption{Fragment of the seismic profile across the eastern slope of the
Lomonosov Ridge
 [\itc{Jokat,} \reflink{Joka05}{2005}] modified by
 [\itc{Rekant et al.,} \reflink{Reka12}{2012}].
  Line $D_1$ corresponds to the Regional unconformity RU and line A is the base of the
Eocene deposits. Cretaceous deposits are located below line B.}
\end{figure*}

\section{Probable Mechanisms of the Subsidence}

\begin{sloppypar}
     A number of deep sedimentary basins exist on the continents and on their
margins. Many basins contain large volumes of hydrocarbons, which makes the
problem of basin formation very important. Several mechanisms have been
proposed to explain the subsidence of the continental crust. Among these
mechanisms, vertical displacements of the lithosphere driven by the convective
flows in the underlying mantle (dynamic topography) are very popular
 [\itc{Flament et al.,} \reflink{Flam13}{2013};
 \itc{Lithgow-Bertelloni and Silver,} \reflink{Lith98}{1998}].
 As noted above, the magnitude
of the crustal subsidence on the Lomonosov Ridge is about 1~km in its axial part
and reaches 2--2.5~km on the ridge's margins. Such a subsidence due to the
dynamic topography should produce intense negative free-air anomalies over the
ridge. However, in reality, the positive free-air anomalies with an amplitude of a
few tens of milligals exist over the ridge
(Figure 3.1.2 in
[\itc{Piskarev et al.,} \reflink{Pisk16}{2016}]).
Another mechanism is a lithospheric flexure under the loading of a large nappe or
under a pull of the subducted plate attached to the edge of the plate that remains
on the surface
[\itc{Allen and Allen,} \reflink{Alle13}{2013};
 \itc{Watts,} \reflink{Watt01}{2001}].
In the Neogene, there were
no convergent boundaries close to the Lomonosov Ridge, which rules out the
possibility that crustal subsidence was this mechanism.
\end{sloppypar}

 \begin{sloppypar}
    Crustal thinning due to lateral extension with the related isostatic
subsidence was initially proposed for the Baikal Graben
 [\itc{Artemjev and Artyushkov,} \reflink{Arte68}{1968}, \reflink{Arte71}{1971}].        %%% ??? 1968 � ���. +
  It was assumed that viscous deformations develop in
the lower, heated, part of the crust whereas the upper crust becomes split into
blocks by large normal faults. Various possible modes of extension of the
lithospheric layer were suggested later (e.g.,
[\itc{McKenzie,} \reflink{McKe78}{1978};
 \itc{Wernicke,} \reflink{Wern85}{1985}]).
In the pure shear model, the intensity of stretching $\beta$ can be determined from the
depth $h_w$ of the water-loaded basin formed after the complete cooling of the crust
and mantle in the lithospheric layer. In the case of local isostasy,
\begin{equation}\label{1}
\beta =
\{1 - [(\rho_m - \rho_w)/(\rho_m - \rho_c)](h_w/h_c^0)\}^{-1}  	% (1)
\end{equation}
Here, $\rho_m = 3.33$~g/cm$^3$ is mantle density,
$\rho_w = 1.03$~g/cm$^3$ is water density,
$\rho_c = 2.84$~g/cm$^3$ is crustal density, and
$h_c^0 = 40$~km is the initial thickness of the
continental crust. Assuming in
formula
\eqref{1}  % (1)
$h_w = 1-2$~km for the water depth in the
basin that was formed in the early Miocene, we obtain
\begin{equation}\label{2}
 	\beta = 1.12 - 1.23	 	 	 	 	 	 	 %	(2)
 \end{equation}
The subsidence began 18.2 Myr ago. During that time, a new temperature
distribution could not have been established in the crust and underlying mantle.
Therefore, formula
\eqref{2}  % (2)
gives the minimum stretching intensity which would be
necessary to produce the observed subsidence.
\end{sloppypar}

\begin{figure*}[t]                     % Fig 5
\figurewidth{35pc}
\setimage{}{}{35pc}{}{2018es000652-f05}
\crosscaption{Tilted blocks in the northern margin of the Bay of Biscay (modified
after [\itc{Pinet et al.,} \reflink{Pine87}{1987}]).
Dashed lines indicate boundaries between the main
seismic complexes; the numbers denote P-wave velocities (km/s).}\vspace*{\baselineskip}
\end{figure*}

\begin{sloppypar}
     Rifted terrains with considerable lithospheric stretching are quite numerous
(see, e.g.,
[\itc{Artyushkov,} \reflink{Arty93}{1993};
\itc{Ziegler,} \reflink{Zieg92}{1992}]).
  In particular, they are widespread
in the North Sea, East Africa, and Eastern China. These regions are characterized
by intense deformations of the basement with normal faulting and splitting of the
upper crust into a set of the large blocks
(\figref{5}).           % (Fig. 5).
The blocks become tilted to
cover the stretched lower crust. The tilt angle $\theta$ increases with the intensity of
stretching $\beta$ as
[\itc{Artyushkov,} \reflink{Arty93}{1993}]:
\begin{eqnarray*}%\label{3}
\theta = \alpha - \arcsin[(\sin\alpha) /\beta] 	 	 	 %	(3)
\end{eqnarray*}
Here, $\alpha$ is the initial dip angle of the normal faults. With a typical $\alpha$ value of
$\sim 25\deg$ and $\beta= 1.23$ (which corresponds to $h_w = 2$~km)
\begin{eqnarray*}   %\label{4}
\theta = 5\deg  	 	 	 	 	 	 	 	% 	(4)
\end{eqnarray*}
The blocks with these tilt angles can be easily noticed in the Cenozoic deposits in
the high-quality seismic reflection profiles across the Lomonosov Ridge.
However, no tilted blocks are observed in the profiles. For example, in the profile
shown in
\figref{2},           % Fig. 2,
at the ACEX drilling site, all the beds in the Cretaceous
sedimentary cover are continuous. Similarly, in the profile in
\figref{4},           % Fig. 4,
 the
continuity can be traced along the reflector D$_1$ corresponding to the Regional
unconformity as well as along the reflector A which is the base of the Eocene
units. These data indicate that the deep-water basin on the Lomonosov Ridge
could not be produced by lithospheric stretching.
\end{sloppypar}


\section{Crustal Subsidence due to Metamorphic Reactions in the Crustal Layer}

     In the absence of significant stretching and large isostatic anomalies over
the Lomonosov Ridge, the formation of a deep-water basin in the early Miocene
can only be explained by the increase in the rock density in the crustal layer. This
mechanism was previously proposed for explaining the formation of the ultradeep
basins in the Barents Sea, North Caspian and South Caspian regions
[\itc{Artemieva and Thybo,} \reflink{Arte13}{2013};
\itc{Artyushkov et al.,} \reflink{Arty14}{2014};
\itc{Gac et al.,} \reflink{Gac12}{2012}]

     Under the conditions of local isostasy the formation of a water-loaded basin
with depth $h_w$ requires that gabbro with density $\rho_{\mathrm{gb}}$ would pass into eclogite with
density $\rho_e$ in the gabbro layer with thickness
\begin{eqnarray*} %\label{5}
h_{\mathrm{gb}} =
(\rho_e / \rho_m) [(\rho_m - \rho_w)/(\rho_e - \rho_{\mathrm{gb}})]h_w  % (5)
\end{eqnarray*}
Assuming $\rho_e = 3.4$~g/cm$^3$,
$\rho_{\mathrm{gb}} = 2.9$~g/cm$^3$, and
$h_w = 1-2$~km with the other
parameter values indicated above, we find
\begin{eqnarray*} %\label{5}
	h_{\mathrm{gb}} = 4.7 - 9.4 \; \mathrm{km}   	 	 	 	 	 	 	% 	(6)
\end{eqnarray*}
     Seismic refraction soundings in the southern part of the Lomonosov Ridge
with the water depth indicated above show that the Moho depth is by \mbox{6--7~km}
smaller beneath the ridge than beneath the adjacent shelf
(\figref{6})           % (Fig. 6)
[\itc{Poselov et al.,} \reflink{Pose14}{2014}].
 It is most probable that this boundary is underlain by eclogites which are
denser than mantle peridotites. However, eclogites are characterized by P-wave
velocities typical of mantle peridotites and, according to the seismic data, these
rocks are commonly placed below the Moho. Thus, it is quite probable that the
Moho beneath the Lomonosov Ridge is underlain by dense mafic eclogites which
actually pertain to the crust as suggested by their mineralogical composition.

\begin{figure*}[t]                     % Fig 6
\figurewidth{35pc}
\setimage{}{}{35pc}{}{2018es000652-f06}
\crosscaption{Velocity model of the Earth's crust along the Arctic-2007 profile
[\itc{Poselov et al.,} \reflink{Pose14}{2014}].
RU is the Pre-Miocene regional unconformity, pCU is
Post-Campanian unconformity, AB is acoustic basement, MS is the top of the
metasedimentary layer, B is the top of the upper crust, L is the top of the lower
crust, M is Moho, 6.1 are P-wave velocities (km/s), the dotted blue lines are main
unconformities in the time-to-depth transformed seismic profile A-7.}
\end{figure*}


     In the presence of fluids, the rate of metamorphic reactions increases by
orders of magnitude
[\itc{Austrheim,} \reflink{Aust87}{1987};
\itc{Jamtveit and Austrheim,} \reflink{Jamt10}{2010}].
Hence,
rapid transformation of gabbro into eclogites in the lowermost crust of the
Lomonosov Ridge in the early Miocene can be hypothetically thought of as the
result of metamorphism under infiltration of fluids from the mantle.

     Rapid crustal subsidence with the formation of deep-water basins is a
typical feature of the large hydrocarbon basins such as the North Caspian and
West Siberian basins and many others
[\itc{Artyushkov,} \reflink{Arty93}{1993}].
Therefore, it is quite
probable that the Lomonosov Ridge pertains to the same basin type.

\section{Conclusions}

\begin{sloppypar}
     As follows from the data presented above, rapid formation of a deep-water
basin on the Lomonosov Ridge occurred without significant stretching of the
lithospheric layer. In the absence of the large free-air gravity anomalies above the
ridge, the subsidence required a considerable increase in the density of the rocks
within the crust due to the metamorphic reactions. Strong acceleration of
metamorphism was possible under the infiltration of fluids from the mantle.
Similar episodes of rapid crustal subsidence with the formation of deep-water
basins took place in many sedimentary basins
[\itc{Artyushkov,} \reflink{Arty93}{1993};
\itc{Artyushkov et al.,} \reflink{Arty14}{2014}].
 It is probable that several other deep-water basins located to the east of
the Lomonosov Ridge in the Central Arctic, the Makarov and Podvodnikov
basins, as well as the deeply submerged Mendeleev High were also formed by
this mechanism.
\end{sloppypar}


\acknowledgments{This study was carried out as a part of the State Research Program 0144-2014-0086
at the Schmidt Institute of Physics of the Earth, Russian Academy of Science and the Program AAAA-A16-116042010088-5 at the Moscow State University, Earth Science Museum.
}

\begin{references}

\reference{Alle13}
\reftype{3}
\refauthf{Allen}{P. A.}{}
\refauth{Allen}{J. R.}{}
\refyear{2013}
\refbook{Basin Analysis: Principles and Application to Petroleum Play Asessment, 3rd Edition}
\refpubl{Wiley-Blackwell}
\reflocat{Oxford}
\refpages{619}
\endreference{}

\reference{Arte68}          %%% 1969 � ������
\reftype{1}
\refauthf{Artemjev}{M. E.}{}
\refauth{Artyushkov}{E. V.}{}
\refyear{1968}
\reftitle{On the origin of rift valleys}
\refjour{Proceedings of the Russian Academy of Sciences, Ser. Geology}
\refnumb{4}
\refpages{58--73}
\endreference{in Russian}

\reference{Arte71}
\reftype{2}
\refauthf{Artemjev}{M. E.}{}
\refauth{Artyushkov}{E. V.}{}
\refyear{1971}
\reftitle{Structure and isostasy of the Baikal rift and the mechanism of rifting}
\refjour{J. Geophys. Res.}
\refvol{76}
\refnumb{5}
\refpages{1197--1211}
\refdoi{10.1029/JB076i005p01197}
\endreference{}

\reference{Arte13}
\reftype{1}
\refauthf{Artemieva}{I. M.}{}
\refauth{Thybo}{H.}{}
\refyear{2013}
\reftitle{Moho depth and crustal structure in Europe, Greenland, and the North Atlantic region}
\refjour{Geophysical Research Abstracts}
\refvol{15}
\refpages{EGU2013-1791}  % ???% ???
\endreference{\href{http://meetingorganizer.copernicus.org/EGU2013/EGU2013-1791.pdf}{http://meetingorganizer.cope rnicus.org/EGU2013/EGU2013-1791.pdf}}

\reference{Arty93}
\reftype{3}
\refauthf{Artyushkov}{E. V.}{}
\refyear{1993}
\refbook{Physical Tectonics}
\refpubl{Nauka}
\reflocat{Moscow}
\refpages{456}
\endreference{in Russian}

\reference{Arty14}
\reftype{2}
\refauthf{Artyushkov}{E. V.}{}
\refauth{Belyaev}{I. V.}{}
\refauth{Kazanin}{G. S.}{}
\refauth{Pavlov}{S. P.}{}
\refauth{Chekhovich}{P. A.}{}
\refauth{Shkarubo}{S. I.}{}        %%% !!!
\refyear{2014}
\reftitle{Formation mechanisms of ultradeep sedimentary basins: the North Barents basin. Petroleum potential implications}
%\refjour{Russian Geology and Geophysics}
\refjour{Russ. Geol. Geophys.}
\refvol{55}
\refpages{649--667}
\refdoi{10.1016/j.rgg.2014.05.009}
\endreference{}

\reference{Aust87}
\reftype{2}
\refauthf{Austrheim}{H.}{}
\refyear{1987}
\reftitle{Eclogitization of lower crustal granulites by fluid migration through shear zones}
\refjour{Earth Planet. Sci. Lett.}
\refvol{81}
\refpages{221--232}
\refdoi{10.1016/0012-821X(87)90158-0}
\endreference{}

\reference{Back06}
\reftype{1}
\refauthf{Backman}{J.}{}                                       %\refauth{Moran}{K.}{} \refauth{McInroy}{D.\! B.}{}
\refgroup{et al.}
\refyear{2006}
\reftitle{Sites V0001-M0004}   % ???
\refjour{Proceedings of the Integrated Ocean Drilling Program}
\refvol{302}
\refpages{169}
\endreference{}

\reference{Back08}
\reftype{2}
\refauthf{Backman}{J.}{}
\refauth{Jakobsson}{M.}{}
\refauth{Frank}{V.}{}
\refgroup{et al.}
\refyear{2008}
\reftitle{Age model and core-seismic integration for the Cenozoic Arctic Coring Expedition sediments from the Lomonosov Ridge}
\refjour{Paleoceanography}
\refvol{23}
\refpages{PA1S03}
\refdoi{10.1029/2007PA001476}
\endreference{}

\reference{Doss17}
\reftype{2}
\refauthf{D{\o}ssing}{A.}{}
\refauth{Gaina}{C.}{}
\refauth{Brozena}{J. M.}{}
\refyear{2017}
\reftitle{Building and breaking a large igneous province: An example from the High Arctic}
\refjour{Geophys. Res. Lett.}
\refvol{44}
\refdoi{10.1002/2016GL072420}
\endreference{}

\reference{Flam13}
\reftype{2}
\refauthf{Flament}{N.}{}
\refauth{Gurnis}{M.}{}
\refauth{M\"{u}ller}{R. D.}{}
\refyear{2013}
\reftitle{A review of observations and models of dynamic topography}
\refjour{Lithosphere}
\refvol{5}
\refnumb{2}
\refpages{189--210}
\refdoi{10.1130/L245.1}
\endreference{}

\reference{Gac12}
\reftype{2}
\refauthf{Gac}{ S.}{}
\refauth{Huismans}{ R. S. }{}
\refauth{Podladchikov}{ Yu. Yu. }{}
\refauth{Faleide}{J. Y.}{}
\refyear{2012}
\reftitle{On the origin of the ultradeep East Barents Sea basin}
\refjour{J. Geophys. Res.}
\refvol{117}
\refpages{B04401}
\refdoi{10.1029/2011JB008533}
\endreference{}

\enlargethispage{-8\baselineskip}

\reference{Gran11}
\reftype{4}
\refauthf{Grantz}{A.}{}
\refauth{Hart}{P.}{}
\refauth{Childers}{V.}{}
\refyear{2011}
\reftitle{Geology and tectonic development of the Amerasia and Canada Basins, Arctic Ocean}
\refbook{Arctic Petroleum Geology. Geological Society (London) Memoirs,
Spencer, A. M., Embry, A. F., Gautier, D. L., Stoupakova, A. V., S{\o}rensen, K. (eds.), vol. 35}
\refpubl{Geological Society}
\reflocat{London}
\refpages{771--799}
\endreference{}

\reference{Jako07}
\reftype{2}
\refauthf{Jakobsson}{M.}{}
\refauth{Backman}{J.}{}
\refauth{Rudels}{B.}{}
\refauth{Nycander}{J.}{}
\refgroup{et al.}
\refyear{2007}
\reftitle{The early Miocene onset of a ventilated circulation regime in the Arctic Ocean}
\refjour{Nature}
\refvol{447}
\refpages{986--990}
\refdoi{10.1038/nature05924}
\endreference{}

\reference{Jamt10}
\reftype{2}
\refauthf{Jamtveit}{B.}{}
\refauth{Austrheim}{H.}{}
\refyear{2010}
\reftitle{Metamorphism: The Role of Fluids}
\refjour{Elements}
\refvol{6}
\refpages{153--158}
\refdoi{10.2113/gselements.6.3.153}
\endreference{}

\reference{Joka05}
\reftype{2}
\refauthf{Jokat}{W.}{}
\refyear{2005}
\reftitle{The sedimentary structure of the Lomonosov Ridge between 88\deg N and 80\deg N}
\refjour{Geophysical Journal International}
\refvol{163}
\refpages{698--726}
\refdoi{10.1111/J.1365-246X.2005.02786.x}
\endreference{}

\reference{Kash13}
\reftype{1}
\refauthf{Kashubin}{S. N.}{}
\refauth{Pavlenkova}{N. I.}{}
\refauth{Petrov}{O. V.}{}
\refauth{Milstein}{Ye. D.}{}
\refauth{Shokalsky}{S. P.}{}
\refauth{Erinchek}{M.}{}
\refyear{2013}
\reftitle{Types of the Earth's crust of the Circumpolar Arctic}
\refjour{Regional geology and metallogeny}
\refvol{55}
\refpages{5--20}
\endreference{in Russian}

\reference{Lawv02}
\reftype{2}
\refauthf{Lawver}{L. A.}{}
\refauth{Grantz}{A.}{}
\refauth{Gahagan}{L. M.}{}
\refyear{2002}
\reftitle{Plate kinematic evolution of the present Arctic region since the Ordovician}
\refjour{Spec. Pap. Geol. Soc. Am.}
\refvol{360}
\refpages{333--358}
\refdoi{10.1130/0-8137-2360-4.333}
\endreference{}

\reference{Lith98}
\reftype{2}
\refauthf{Lithgow-Bertelloni}{C.}{}
\refauth{Silver}{P. G.}{}
\refyear{1998}
\reftitle{Dynamic topography, plate driving forces and the African superswell}
\refjour{Nature}
\refvol{395}
\refpages{269--272}
\refdoi{10.1038/26212}
\endreference{}

\reference{McKe78}
\reftype{1}
\refauthf{McKenzie}{D.}{}
\refyear{1978}
\reftitle{Some remarks on the development of sedimentary basins}
\refjour{Earth and Planet. Sci. Lett.}
\refvol{40}
\refpages{25--32}
\endreference{}

\reference{Mora06}
\reftype{2}
\refauthf{Moran}{K.}{}
\refauth{Backman}{J.}{}
\refauth{Brinkhuis}{Y.}{}
\refgroup{et al.}
\refyear{2006}
\reftitle{The Cenozoic paleoenvironment of the Arctic Ocean}
\refjour{Nature}
\refvol{444}
\refpages{601--606}
\refdoi{10.1038/nature04800}
\endreference{}

\reference{Olso15}
\reftype{2}
\refauthf{Olson}{P.}{}
\refauth{Amit}{H.}{}
\refyear{2015}
\reftitle{Mantle superplumes induce geomagnetic superchrons}
\refjour{Front. Earth Sci.}
\refvol{3}
\refpages{38}
\refdoi{10.3389/feart.2015.00038}
\endreference{}

\reference{Pine87}
\reftype{4}
\refauthf{Pinet}{B.}{}
\refauth{Montadert}{L.}{}
\refauth{Mascle}{A.}{}
\refgroup{et al.}
\refyear{1987}
\reftitle{New insights on the structure and formation of sedimentary basins from deep seismic profiling in Western Europe}
\refbook{Petroleum Geol. of North West Europe}
\refpubl{Graham and Trotman}
\reflocat{London}
\refpages{11--31}
\endreference{}

\reference{Pisk16}
\reftype{3}
\refauthf{Piskarev}{A. L.}{}
\refauth{Poselov}{V. A.}{}
\refauth{Avetisov}{G. P.}{}
\refgroup{et al.}
\refyear{2016}
\refbook{Arctic Basin (Geology and Morphology), V. D. Kaminsky (ed.)}
\refpubl{VNIIOkeanGeologiya}
\reflocat{SPb}
\refpages{291}
\endreference{in Russian}

\reference{Pose14}
\reftype{3}
\refauthf{Poselov}{V. F.}{}
\refauth{Butsenko}{V. V.}{}
\refauth{Chernykh}{A. A.}{}
\refauth{Glebovsky}{Y. Y.}{}
\refgroup{et al.}
\refyear{2014}
\refbook{The structural integrity of the Lomonosov Ridge with the North American and Siberian continental margins}
\refpubl{VSEGEI}
\reflocat{SPb}
\refpages{332}
\endreference{}

\reference{Reka12}
\reftype{4}
\refauthf{Rekant}{P.\! V.}{}
\refauth{Gusev}{E.\! A.}{}
\refauth{Vinogradov}{V.\! A.}{}
\refyear{2012}
\reftitle{Horst-graben structures of the Lomonosov Ridge sedimentary cover: history of formation and linkages with the Siberian shelf}
\refbook{Geophysical Institute Report UAG-R}
\refpubl{University of Alaska}
\reflocat{Fairbanks, Alaska}
\refpages{165--167}
\endreference{}

\reference{Watt01}
\reftype{3}
\refauthf{Watts}{A. B.}{}
\refyear{2001}
\refbook{Isostasy and Flexure of the Lithosphere}
\refpubl{Cambridge University Press}
\reflocat{Cambridge}
\refpages{458}
\endreference{}

\reference{Wern85}
\reftype{2}
\refauthf{Wernicke}{B.}{}
\refyear{1985}
\reftitle{Uniform-sense normal simple shear of the continental lithosphere}
\refjour{Canadian Journal of Earth Sciences}
\refvol{22}
\refnumb{1}
\refpages{108--125}
\refdoi{10.1139/e85-009}
\endreference{}

\reference{Zieg92}
\reftype{2}
\refauthf{Ziegler}{P. A.}{}
\refyear{1992}
\reftitle{North Sea rift system}
\refjour{Tectonophysics}
\refvol{208}
\refpages{55--75}
\refdoi{10.1016/0040-1951(92)90336-5}
\endreference{}

\vspace*{2.2pc}

\end{references}


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