Deep Structure Research
of the Earth after
the International Geophysical
Year
(Geotraverse Project
and InterMARGINS)
A.G.Rodnikov, N.A.Sergeyeva, L.P.Zabarinskaya
Geophysical Center, Russian Academy of Sciences
Moscow, Russia
First International Polar Year (1882-1883)
Karl Weyprecht
(1838 -1881)
Austro-Hungarian navy officer,
Arctic explorer who discovered
Franz Josef Land, an archipelago
north of Russia, and who
advanced a successful scheme
for international cooperation in
polar scientific investigations but
died before it first occurred in
1882-1883 .
The International Geophysical Year 1957 – 1958
inspired by the IPY and occurred 75 years after the first IPY
The Bureau of the special
IGY Committee in Brussels
in 1957.
M. Nikolet (Belgium),
General Secretary of the
Committee, ( in the center);
to the left of him:
L. Berkner (USA), VicePresident,
V. V. Beloussov (USSR),
Bureau member and later
Vice-President,
and to the right of him
J. Kulon (France)
Bureau member,
C. Chapman (Great
Britain), Committee
President
Emblem of IGY 1957-1958
The International Geophysical Year 1957 – 1958
Academician I. P. Bardin,
Chairman of the Soviet
Committee for IGY,
Vice-President of the USSR
Academy of Sciences
informs on the conference
for press that
the Soviet Union intends to
launch the artificial
satellite of the Earth during
the International
Geophysical Year (IGY).
Barcelona, 1955.
Non-magnetic schooner “Zarja”
Russian non-magnetic
oceanographic research
vessel ZARJA (or ZARYA).
Built 1952 in Finland,
333grt, wood auxiliary
three-masted schooner.
North Pole Drifting Station SP-7
*
Drifting station SP-7
conducting
observations in the
Arctic regions
from April 23, 1957
till
April 11, 1959,
Distance = 3520 km
*Soviet and now Russian drifting ice stations are named "Severnyy polyus“
(Russian: «Северный полюс»; English: "North Pole") and are abbreviated SP
(Russian: «СП»; English: "NP"). Each station is assigned an ordinal number.
Soviet and American Researches
in the South Pole
Results of IGY 1957-1958
Press-conference
on IGY results.
Professor V. V.
Beloussov is
speaking.
From left to right
A. D. Powsner,
N. V. Shebalin,
N. V. Pushkov and
V. A. Magnitsky.
Moscow, 1963.
After the International Geophysical Year
1957 – 1958
New Projects
Ocean Margins
Ocean Margins
Gulf of California
(San Andreas Fault Observatory at Depth)
Drilling the San Andreas Fault at
Depth
The first of these drilling projects is
making a borehole next to the San
Andreas fault
near Parkfield, California, at a
depth of about 3 kilometers. Drilling
began in 2004 with a vertical hole
going down 1500 meters, then
curving toward the fault zone.
The 2005 work season extends this
slanting hole all the way across the
fault, and is being followed by two
years of monitoring.
Project “CRISP” (Costa Rica Seismogenesis Project)
InterMARGINS, Newsletter No 4, 2004
CRISP is a project to understand the
initiation of large earthquakes and
seismic rupture by drilling on either side
of the updip limit of seismogenesis. The
shallow dip of the subduction zone off
southern Costa Rica and relatively high
subducting plate temperature cause this
seismogenic environment to rise to
drilling depth.
Materials, temperature, lithification, fluid
flow and chemical changes that occur
down the subduction zone are
hypothesized to cause the transition from
stable to unstable slip that ultimately
results in great earthquakes. Along the
erosional convergent margin of Costa
Rica the seismogenic plate interface is
surrounded by eroded debris rather than
by trench sediment.
New
Subduction
Zone in
the Japan Sea
http://www.gcras.ru/index_e.html
Geophysical Center
of the Russian Academy of Sciences took part in the
fundamental researches on the deep cross-sections of the
lithosphere through the marginal seas in a transition zone
from Asian continent to the Pacific Ocean investigated under
the Geotraverse International Project
and InterMARGINS
Area of Research
The deep structure of the
Eurasia-Pacific transition zone
was investigated under the
Geotraverse Project and
InterMARGINS along the deep
sections of the tectonosphere,
including the lithosphere and the
asthenosphere. The first
geotraverse, was preparated in
cooperation with Japanese
geoscientists, crossed the region
of the Japan Sea. The second
geotraverse, carried out in
cooperation with Japanese and
Chinese geoscientists, crossed
the region of the Philippine Sea
and the North China Plain. The
third geotraverse crossed the
region of the Okhotsk Sea.
Seismicity
The Eurasia-Pacific
Transition Zone
Distribution
of
Heat flow
The Eurasia-Pacific
Transition Zone
The Japan Sea Geotraverse
Seismic Profile along
the Philippine Sea Geotraverse
The North China Plain-Philippine Sea
Geotraverse
There are correction between asthenosphere and formation of deep basins. Under Paleogine
West Philippine Basin the asthenosphere lies at the depth of 50-70 km. Under the Neogene
Parece Vela basin the asthenosphere lies at the depth of 30 km. Under the Mariana Trough the
asthenosphere reaches the crust causing active tectonic and magmatic processes.
The Okhotsk Sea Geotraverse
Tectonic Scheme
Compiled from the data of
Maruyama et al., 1997;
Cruise ..., 2000;
Zonenshain et al., 1990;
Kiratzi and Papazachos,
1996;
Rodnikov et al., 2001
The Okhotsk Sea region is a large Lithospheric plate of the transition zone from
Asian continent to the Pacific. It is located in the contact zone of three Lithospheric
plates : Eurasian, North American and the Pacific. Arrows show plate movement
direction.
Deep Structure of
Deryugin Basin and
North Sakhalin
Basin
(Sea of Okhotsk)
The Deryugin Basin was formed in the Cenozoic at the site of the ancient deep trench after the subduction of the
Okhotsk Sea Plate under Sakhalin had been completed in the Early Paleogene. The North Sakhalin oil and gas basin
was formed at the site of the Late Cretaceous bark-arc basin. The Deryugin basin is located above a hot plume in the
mantle that is asthenospheric diapir of partial melting revealed at a depth of 25 km. The west side is bounded by
ophiolite belt of ultramafic magmatic rocks, which confine an ancient (K 2-Pg) paleosubduction zone separating
Deryugin Basin from North Sakhalin basin.
The Upper Mantle for the Sea of Okhotsk
Seismic tomography model of the upper mantle in the Okhotsk Sea (Bijwaard, 1998). There
are two subduction zones: ancient (Triassic-Cretaceous), the subduction Okhotsk Sea plate
under Asian Continent and recent, the subduction Pacific plate under Kamchatka.
A
B
Asthenosphere
and
Moho
beneath
the Sea of Okhotsk
C
The Model of the of the Lithosphere structure of the Sea of Okhotsk.
A-the Okhotsk Sea floor relief. B - Moho. C - asthenosphere. The asthenosphere in the upper mantle of the Sea of
Okhotsk is located at a depth of 50 - 70 km and beneath the Northwestern Pacific basin it is revealed at a depth of 100
km. Diapirs of partial melting come off the asthenosphere, reaching a depth of 25 - 30 km beneath the Tatar Strait
Trough, Deryugin Basin and Kuril Basin and causing an active tectonic regime manifested in volcanic, seismic and
hydrothermal activity. Red color shows the area of magma formation.
The Okhotsk Sea Geotraverse
The Okhotsk Sea Geotraverse crosses the Sikhote Alin, Sakhalin, Kuril Basin, Kuril Island Arc and Pacific. The
thickness of the crust varies from 35-40 km under Sakhalin and the Kuril Islands to 8-10 km under the Kuril Basin. In
the Cenozoic, the large part of the sedimentary basins was formed. The asthenosphere in the upper mantle is separated
mostly from geothermal data. The upper surface of the asthenosphere is an isotherm 1000-1200C, the temperature of
partial melting. The asthenosphere is located in the upper mantle of the Sea of Okhotsk at a depth of 50-70 km. From
the asthenosphere the diapirs go off that reach a depth of 20-30 km beneath the sedimentary trough of Tatar Strait and
Kuiril Basin, causing an active tectonic regime.
Conclusions




A distinctive feature of the transitional zone between the Eurasian continent and the Pacific
Ocean is the presence of an asthenosphere in the upper mantle.
The tectonically active regions, such as the island arcs and the rifts of the marginal seas,
correlate with a thick, magma-generating asthenosphere. The asthenospheric diapirss are
marked on the surface by rift formations and mainly tholeiitic magma eruption.
The asthenosphere resides in a depth of 50-80 km under the old Paleogene deep basins of the
marginal seas, at about 30 km under the Neogene basins, and at a depth of 10-20 km under
the Pliocene-Quaternary and recent inter-arc basins, causing the breaks of the lithosphere, the
formation of rifts, basalt lava eruptions, and hydrothermal activity
Rifts in the marginal seas and island arcs may by accompanied by intense mineralization. The
combination of high heat flow, volcanicity and hydrothermal activity in these structures, in
the past and at present, can lead to the formation of sulfides and non-metalliferous mineral
deposits.
The formation of the sedimentary basins is associated with recent and ancient subduction
zones. The sedimentary basins are characterized by:
- rift structures or spreading centers at their basement;
- active magmatism at the initial stage of formation;
- hydrothermal processes associated with sulphides formation;
- high density of heat flow caused by the uplift of the asthenosphere to the crust;
- localization of asthenosphere diapirs in the upper mantle;
- asthenospheric diapirs are channels, along which hot mantle fluids from the asthenosphere
penetrate into the sedimentary basins and other units transition zone.