SGL36-01

Japan Geoscience Union Meeting 2016

Evaluation of micro-fabric network within marine sediments based on a rock magnetic
technique and its tectonic implications*Yasuto Itoh1, Osamu Takano2, Machiko Tamaki3
1.Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 2.Japan
Petroleum Exploration Co., Ltd., 3.Japan Oil Engineering Co., Ltd.
Magnetic techniques that use anisotropy of magnetic susceptibility (AMS) act as a proxy ofpreferred permeable orientation in basin-filling sediments, when it is applied on samples
impregnated with a finely-ground magnetic suspension. The unique method for quantifying
heterogeneity in rocks is reviewed and its value for reconstruction of the preferred direction ofpore fluid flow is reassessed critically. The authors also present results of their experiments,
which dealt with secondary fracture networks developed in tight sandstones burying a foreland basinon an arc-arc collision zone in central Hokkaido. Micro-focus three-dimensional density imaging oftest pieces of the Miocene Kawabata Formation has shown a substantial variation in pore fabricreflecting inhomogeneous impregnation of magnetic fluid within rocks. Directional analysis of AMS
ellipsoid implies tectonic control on rupture development under strong trans-compressive regime.
Keywords: permeability, magnetic susceptibility, anisotropy, sedimentary basin, fracture, tectonics©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Tectonics of southern Osaka Plain based on dislocation modeling and subsurface data
*Naoto Inoue1, Naoko Kitada1, Keiji Takemura2
1.Geo-Research Institute, 2.Institute for Geothermal Science, Kyoto University
The Osaka basin is surrounded by E-W trending strike slip faults and N-S trending reverse faults.
The N-S trending 42-km-long Uemachi faults traverse in the central part of the Osaka city. The
Ministry of Education, Culture, Sports, Science and Technology started the project to survey the
Uemachi faults from 2009 to 2012 for countermeasures against earthquake disaster.
The various geological, geophysical surveys, such as seismic reflection, micro tremor, gravity
surveys and deep boreholes, revealed the complex basement configuration along the Uemachi faults.
The survey results revealed not only the detail subsurface structure of the Uemachi fault, but also
E-W trend structure. Sugiyama and Imanishi (2015) explained the E-W trending structure caused bydeep-seated fluids.
In the south part of the plain, there were difference between the depth of the basement, estimatedby gravity analysis and seismic reflection surveys (Osaka Prefecture, 2005; Inoue et al., 2014).
This suggests the density of the sediment or the basement of the north and the south part of theplain differs. The difference is considered as the variation of density contrast due to some local
distribution of the volcanic rocks. The magnetic anomaly indicates higher value at these points.
The density structure was discussed from the gravity anomaly in consideration of the high magnetic
anomaly area (Itoh et al., 2012).
Kusumoto et al. (2001) reported that surrounding faults enable to form the similar basement relief
without the Uemachi faults model based on a dislocation model. Inoue et al. (2013) performed
various parameter studies for dislocation model based on Kusumoto et al. (2001). The model was
consisted 11 faults, the Rokko-Awaji, ATL, MTL, Ikoma, Eastern Nara, Osaka-wan, Kongo, the Northand South Uemachi faults and, Sakuragawa and Suminoe flextures. The dislocation was calculated
based on the Okada et al. (1985). The results show the similar basement displacement pattern to theactual basement configuration.
In this presentation, the dislocation simulation with surrounding faults and other source suggested
by Sugiyama and Imanishi (2015) will be performed and the comparison with inversion results ofgravity anomaly and dislocation model will be shown.
This research is partly funded by the Comprehensive Research on the Uemachi Fault Zone (from FY2010
to FY2012) by The Ministry of Education, Culture, Sports, Science and Technology (MEXT).
Keywords: Osaka Basin, Dislocation model, Potential Data

©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Outline of basin formation tectonics in the NE and SW Japan Arcs since the opening of the
Sea of Japan*Takeshi Nakajima1
1.Institute for Geo-Resources and Environment, Geological Survey of Japan, National Institute ofAdvanced Industrial Science and Technology
Basin formation tectonics along convergent margins may vary according to the variation incharacteristics of plates and their styles of subduction. In this presentation, basin formation
tectonics in the NE and SW Japan Arcs since the opening of the Sea of Japan will be compared.
Tectonic Stages in both the NE and SW Japan Arcs are roughly divided into the rifting stage and thepost-rifting stage. Early rifting sub-stage in the rifting stage commenced at Eocene and wascharacterized by formation of small rift basins associated with volcanism along the present Sea ofJapan coasts in both the NE and SW Japan Arcs. Regional unconformity was formed in both the NE andSW Japan Arcs in Late Oligocene, which suggests a common tectonic setting between the NE and SW
Japan Arcs. During the syn-rifting sub-stage in Early Miocene, regional transgression commenced
simultaneously in back arc regions of the NE and SW Japan Arcs at 18 Ma. While large rift basins
were restricted along the Sea of Japan coast of the SW Japan Arc, deep rift basins were formed in
the present backbone range of the NE Japan Arc.
Rifting terminated at 15 Ma in the SW Japan Arc with regional uplift and emergence, which were
followed by extraordinary volcanism such as fore-arc volcanism and high-Mg andesite activities in
Setouchi region. In contrast, back arc region of the NE Japan Arc subsided to have been deep
basins. Rifting associated with subsidence and volcanism had continued in the backbone basins in
the NE Japan Arc until 13.5 Ma. This notable difference in tectonics between the NE Japan and SW
Japan Arcs was succeeded during the post-rifting stage. While most of the SW Japan Arc remained
emerged without intense basin formation by Pliocene, the NE Japan Arc had experienced intermittent
uplift and unconformity events and had gradually been emerged since Late Miocene.
Conventional plate reconstruction models commonly assumed that the Pacific Plate had subducted toboth the NE and SW Japan Arcs in the early rifting sub-stage and that the young Shikoku Basin in
the Philippine Sea Plate replaced the Pacific Plate and subducted to the SW Japan Arc by sometime
either during the syn-rifting sub-stage or during the post-rifting stage. Differences in basinformation tectonics between the NE and SW Japan Arcs after the late syn-rifting sub-stage can be
attributed to differences in characteristics of subducting plates, in the styles of back arc
rifting reflecting complex basin formation processes in the Sea of Japan, and in the styles ofdrifting of the NE and SW Japan Arcs.
Keywords: basin formation tectonics, NE Japan Arc, SW Japan Arc, rifting stage, post-rifting stage,
opening of the Sea of Japan©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Forearc and backarc basin-filling stratigraphy as an archive of plate tectonic history*Osamu Takano1,2,3
1.Japan Petroleum Exploration, JAPEX Research Center, 2.JOGMEC, 3.AIST
Basin-filling stratigraphy can be defined as “the study of basin-filling sediments from thestandpoints of unconformity events, stress regimes, succession trends and three-dimensional
development patterns of depositional systems with consideration of their controlling factors suchas plate tectonic conditions.” The basic unit of basin filling stratigraphy can be atectono-sequence unit, which can be bounded by regional major unconformities, or the turning pointsof stress regimes, basin evolution stages and succession trends of depositional systems such as
upward shallowing and deepening trajectories. This paper presents representative cases ofbasin-filling stratigraphy for forearc basins and backarc to intraarc basins, which might bereflecting the plate tectonic histories, using examples of the NE and SW Japan convergent margins.
The basin filling stratigraphy of forearc basins is strongly controlled by the morphologicalvariation and volcanic arc setting, both of which influence internal unconformity formation,
sediment supply, differences in depositional systems and succession trends. The marine sloped tosubmerged ridge type is mainly filled with deep marine turbidites or shales. The terraced toshelved, overfilled type commonly shows a transgressive to regressive pattern consisting of
turbidite, slope, shelf to shallow marine systems in response to the increase of clastic supply
from the adjacent volcanic arc. Internal deformation of basin filling sediments is quite common incase the forearc setting is compressional. The benched type, which has an emergent trench slope
break ridge, characteristically shows a regressive succession from marine to fluvial systems, or
thick aggradation of bay to coal-bearing fluvial systems. If the forearc setting maintained for ageologically long time, it is estimated that the morphological forearc basin types can betransferred from the submarine sloped, submerged ridge type to the shelved, benched types, as the
trench slope break ridge tends to develop along with the accretionary prism development due toplate subduction.
The basin filling stratigraphy of backarc to intraarc basins is commonly characterized by the basin
evolution stages, since backarc/intraarc basins are, in most cases, initiated as rift basins, andfollowed by tectonic inversion into a compressional stress field. The boundary between syn-rift andpost rift stages tends to show a regional break-up unconformity, and the inversion stage createsareal uplift-related unconformities. The mass balance between the accommodation space created bysubsidence and sedimentation may control the succession trends for the syn-rift, post rift andtectonic inversion stages. The syn-rift to early post rift stage usually shows a transgressive
upward-deepening succession trend, whereas the tectonic inversion stage causes an upward-shallowing
trend due to increasing sediment supply from the provenance.
Keywords: basin filling stratigraphy, forearc basin, backarc basin, plate tectonics, succession
trend, unconformity event©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Integrated Research for Quaternary Sedimentary Basin in Southwest Japan from the viewpointof Deep drilling data and Seismic interpretation*Keiji Takemura1
1.Beppu Geothermal Researh Laboratory, Institute for Geothermal Sciences, Graduate School of
Science, Kyoto University
Research on Quaternary Sedimentary basins in southwest Japan have been developed with accordance of
research on paleogeography and tectonic development. Most of distribution area of Quaternary
sedimentary basins such as Osaka Bay and Lake Biwa etc. is covered by aquatic or alluvial area, and
it is difficult to make clear the stratigraphy and structure of sequence by using the usual
geological technique at outcrops. Most adequate methods are drilling and geophysical prospecting
such as seismic reflection surveys. I introduce the Quaternary basin formation history in Southwest
Japan using the drilling data and geophysical data from Osaka sedimentary basin, Lake Biwa basin,
Kyoto basin and Beppu bay basin during 40 years.Osaka sedimentary basin was constructed by the
combination of activity of right lateral strike slip movement of Median Tectonic Line andArima-Takatsuki Tectonic Line, and reverse faults of North-South direction, and has precise
subsurface structure in the basin revealed by the distribution of Marine clays deposited undertransgression of about 100,000 years cycles. Lake Biwa basin had been influenced by reversed fault
activity located at western part of basin and northward migration activity. Kyoto basin wasconstructed by the activity of two reverse fault activity. Beppu Bay had been influenced by thetranscurrent movement of Median Tectonic Line and normal fault activity at the termination ofstrong strike slip movement.In conclusion, time series of movement of Philippine Sea Plate
subduction and activity of Median Tectonic Line at forarc region have played an important role forformation of Quaternary basins in southwest Japan.
Keywords: Quaternary sedimentary basin, Core stratigraphy, Seismic interpretation©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Paleomagnetic study of Neogene sediments in strike-slip basins along the Tanakura Fault*Yurie SAWAHATA1, Makoto Okada2, Jun Hosoi3, Kazuo Amano4
1.Graduate School of Sci. and Eng., Ibaraki Univ., 2.College of Sci., Ibaraki Univ., 3.Geological
Survey of Japan, AIST, 4.The Institute of Natural Sciences, College of Humanities and Sciences,
Nihon Univ.
The Tanakura Fault, one of the major tectonic line in Japan, is developed from the Tanagura Town,
Fukushima Pref. to the Hitachiohta City, Ibaraki Pref., with a NNW-SSE trending direction. They
consist of the Eastern Marginal Fault, the Western Marginal Fault and a shear zone between thefaults. The movement of the Tanakura Fault is thought to be related to the Japan Sea opening during
the Early to Middle Miocene (e.g., Jolivet and Tamaki, 1992). Geologic studies have revealed thatstrike-slip basins were developed due to a left lateral movement of the Tanakura Fault (e.g. Amano,
1991). This study aims to refine the chronostratigraphy of geologic sequences of strike-slip basinsdeveloped along the Tanakuura Fault, and to reconstruct a tectonic history of the basin based on
paleomagnetic analyses.
Samples for paleomagnetic analyses were collected from the Yajika Rhyorite, Kitatage Formation,
Kitatage Formation, Osawaguchi Tuff Member and the Nawashiroda Formation in the Yamatsuri, Western
Daigo, Eastern Daigo and Yamagata Basin.
As the results of paleomagnetic analyses, the Kitatage Formation, Osawaguchi Tuff Member, Asakawa
Formation and Nantaisan Volcanic Breccia exhibit non-rotating reversed polarity supposed to becorrelated to the Chron C5Br (ca. 16.04-15.2 Ma). On the other hand, the Nawashiroda Formation
exhibits reversed and normal polarities correlated to the Chrons C5Br, C5Bn, C5ADr (ca.15.2~14.6
Ma) , which associated with a clockwise rotation ca. 20°, suggesting that a counterclockwise
rotation ca. -20° is needed to be at this area before deposition of the Nawashiroda Formation.
Keywords: The Tanakura Fault, strike-slip basin, Japan Sea opening, Middle Miocene, paleomagnetic
study©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Paleomagnetism of the Sorachi and Yezo Group in the Ashibetsu area, central Hokkaido,
Japan.
*Yuki Kitagawa1, Reishi Takashima2, Yasuto Itoh1
1.Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 2.Tohoku
University Museum, Tohoku University
Paleomagnetic study was performed on Upper Jurrasic~Lower Cretaceous Sorachi Group and Yezo Groupin Ashibetsu area, central Hokkaido aiming at quantitative estimation of tectonic movements inreference to the northeastern Eurasia. Characteristic remanent magnetization (ChRM), which iscarried by various ferromagnetic minerals, was isolated for five sites. To determine their origin,
we executed isothermal remanent magnetization (IRM) experiments, and origin of ChRM is categorized
into two groups. One of them is positive in reversal test, and enhanced precision parameter after
tilt correction implied pre-folding origin. Untilted formation mean direction (D=-12.0°, I=47.7°, α95=12.3°)

is characterrized by significantly shallower inclination than the expected value forcoeval mother continent, and northward movement since the Cretaceous is determined to be 2100 km (±
1500 km). In comparison with previous paleomagnetic studies and tectonic models, central Hokkaido
could consist of at least two components and have experienced rapid northward movement driven byplate motion.
Keywords: Paleomagnetism, Hokkaido, Cretaceous©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Tectonic Basin Structure in Kansai Area on the point of subsurface structure using
borehole database*Naoko Kitada1, Ito Hiroko1, Inoue Naoto1, Mitamura Muneki2, Takemura Keiji3
1.Geo-Research Institute, 2.Osaka City Univ. Department of Sciences , 3.Intitute for geothermalsciences, Kyoto University
Kansai Geo-informatics Research committee started to study about subsurface structure around Kansai
Area after the1995 Kobe Earthquake. This committee also carried out the standard borehole survey atthe each area and tried to resolve the relation between geological properties and geotechnicalproperties. The results of this mission were published “Shin-Kansaijiban” series. We are consideredeach borehole data using geological information such as tephra, microfossils, sedimental
environment and so on, and referred to the seismic reflection survey.
The results of this study make clear the tectonic movement of each area. In Osaka area marine clay
layers show the tilting toward to the Ikoma Fault. Other area also find these sign of tectonic
movement from the subsurface borehole data.
Keywords: borehole, database, tectonic movement, sedimentary environment©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

Why arc-shaped archipelago was formed ? How concave plate basin was built ? All origin ofplate tectonics, was solved by unique hypothesis.
*Akira Taneko1
1.SEED SCIENCE Lab.
Origin of plate tectonics, was solved by unique physically meaningful hypothesis.
Even people who stubbornly resist the continental drift theory of Wegener, neither the driving
force is unknown, was no people who oppose to adopting a plate tectonics.As the driving force,
Mantle Convection Hypothesis of Holms 1929, springing up and coming force to press the plate in theridge, the power to pull the plate to crawl into the mantle.
Hard plate flowable layer asthenosphere under the lithosphere and assume a rigid a mesosphere underit the plates to move the surface of the earth without parallel deformed like a rigid body,heashumed.Mantle is springing up from the hot spot, there is the fact that parallel seamount chains
has been formed. And it has also been observed that the driving direction is bent. I believe thatis happening is mantle convection in the difference of basically any driving force is also
density.Problem lithosphere of the same density, can not be proposed first to crawl under the othertwo mechanical rhythm.In addition, not be able to propose mechanisms and reasons for moving
direction was bent.
Multi impact hypothesis, following (A)·a hypothetical two steps (B), as a result (1) - (15).
(A)Protoplanetary CERRA the orbit has been flattened by the Jupiter perturbations, was ruptured in
the tension of Jupiter and the sun.
(B)The cross-sectional mantle lobe is for the track that crosses the Earth, caused the sequential
Mantle Impact.
Results (1)Injecting a month in the collision to the first of the Pacific Ocean position (12.4km /s, 36.5 deg.), and the trajectory of the month was calculated to be 60RE.
(2)Why? Is formed in almost the same orbital plane moon and the solar system, how the moon wasformed only in the mantle? Because collision of the mantle piece.
(3)Meteorite in minute fossil quality achondrites-iron meteorite, which is why a mixed? Cause isMulti Impact.
(4)In the tidal disruption of CERRA, the asteroid belt has been formed energy . Is Kyusetsu is anerror that was not accustomed to substantially equal to the planet in the long axis length..
(5)Caused a large species extinction in the collision over a few degrees. It is an inevitable
collision mechanism that does not rely on chance.
*(6)By the collision of a plurality of cross-sectional mantle lobes, also 70 p/c of the Earthsurface area of the size of the deep sea Yosoko (-5km) has been formed.
*(7)Plate tectonics of the Plate boundary Why was formed in that position? Collision mantle
peeling, vacuum melting and cracking.
*(8)Pacific Rim arc-shaped archipelago and back-arc basin, and Darwin raised by the collision loss
and isostatic, plate is concave in the mantle reduced pressure.
*(9)Was to elucidate the mystery of the origin and driving force of plate tectonics. Driving force= complement of the moment of inertia eccentric due to the collision.
*(10)To back-arc plate, and Pacific Ocean convex plate each other press in the eccentric moment
driving force, starts submarining by isostasy.
*(11)Why form kimberlite pipe in South Africa Premier and Russian Mirunui district? Concentrationand continental drift to Hawaii position to the collision and the impact of the counter electrode,and collision on the opposite side of the Drake Passage of Mirunui mine, Antarctica moved©2016. Japan Geoscience Union. All Right Reserved.

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Japan Geoscience Union Meeting 2016

stabilized.
*(12)Why is earth's axis was tilted 23 deg from the revolution surface? Was estimated to collisionof CERRA division pieces to the Drake (high latitude) position.
*(13)Why, the core of the Earth eccentricity (about 10 %) happened or? CERRA debris collision,
Earth's mantle is missing, isostasy.
(14)Jupiter large red origin of plaques? Form a thermal conductivity difference soliton in thecollision of MI mantle piece .cf. Shoemaker Levy comet.
(15)To outer planet is a gas-ice, or Pluto's is why silicate dwarf planet? In CERRA Mantle debrisof the swing-by.
Keywords: Formation of the arc-shaped archipelago, Formation of a concave plate basin, Origin ofplate tectonics, Multi-Iimpact Hypothesis, The origin of the deep sea floor, Lunar origin©2016. Japan Geoscience Union. All Right Reserved.

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