ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    The @island arc 8 (1999), S. 0 
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Three collisional cycles, the Tanzawa, Izu and Shichito, are known to have occurred in the South Fossa Magna, central Japan, since the late Miocene, based on geologic evidence. The cycles consist of six stages. At present the South Fossa Magna is in the later part of stage 5 of the Izu Cycle and stage 2 of the Shichito Cycle. Because the collisional processes are ongoing we can observe, measure and correlate them with the geologic records of the former cycles. The collisional processes are progressing intermittently because of the rupture and deformation of the collided and colliding island arc crusts. Rupture in the subducting crust can be explained by the geometry of the subducting plate along a boundary that is not straight. The delamination of the upper crust is detected from the geologic and crustal structure in the collided Tanzawa Block; it is an important factor in the deformation of the crust.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    The @island arc 13 (2004), S. 0 
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract  Magnetic measurements were carried out to investigate rock magnetic properties and paleomagnetic directions of late and middle Miocene sediments recovered from the land side of the Japan Trench during the Ocean Drilling Program Leg 186. Because the low coercive component in natural remanent magnetization (NRM) normalized by anhysteretic remanent magnetization shows that the drilling-induced magnetization is severe in the sections obtained by the advanced hydraulic piston coring method, careful analyses of demagnetization of NRM using the ‘demagnetization plane’ were carried out to decompose the direction and intensity. Magnetostratigraphic correlation down to the upper Miocene, supplemented by biostratigraphic data, revealed that the sedimentation rates are characterized by drastic changes, with the early Pliocene having the highest rate. This high sedimentation rate is related to the subsidence of the southern deep-sea terrace of the Japan Trench.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    The @island arc 13 (2004), S. 0 
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract  Seven chronostratigraphic stages were established based on the correlation of magneto-biostratigraphic marker horizons within the Deep Sea Drilling Project and Ocean Drilling Program cores from the forearc of the Japan Trench. Because the stages are coeval with changes in the rate of sedimentation, lithofacies, magnetic intensity and composition of fossil assemblages, they probably reflect the tectonic situation in the Japan Trench forearc and also in the arc–trench system. The stages correlate to the tectonic events of the Japanese Island Arcs; for example, evolution of the Boso triple junction, initiation of Philippine Sea Plate subduction and the Japan Sea opening.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    The @island arc 12 (2003), S. 0 
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract We carried out paleomagnetic measurements and K–Ar dating on Neogene andesitic lavas and sills of the Shigarami Formation in North Fossa Magna, central Japan. The Shigarami Formation is distributed in the axial part of the Komiji Syncline in the folding zone of the southwestern North Fossa Magna. Results of the present study indicate that the Komiji Syncline was formed shortly after 4.42 ± 0.12 Ma during the Pliocene. The sedimentary rocks of the Shigarami Formation consist of shallow marine and fluvial deposits. Intrusions of andesitic sills are found in the shallow marine deposits and two andesitic lava flows are present in the fluvial deposits. Oriented samples were taken from the sills at four sites and from the lavas at three sites. The samples produced stable remanent magnetization through stepwise alternating field and thermal demagnetizations. Results of a positive fold test indicate that the stable remanent magnetizations concentrate around a mean reversed polarity of declination = 169.0°, inclination = −58.5° and 95% confidence limit = 9.0° after corrections have been made according to the direction of the bedding of the sedimentary rocks. Four fresh samples were selected for K–Ar dating from the samples used for paleomagnetic measurements. The groundmass of three samples taken from the sills yield ages of 4.42 ± 0.12, 4.49 ± 0.22 and 4.69 ± 0.13 Ma, whereas the one taken from the lower lava has an age of 5.91 ± 0.26 Ma. We believe that the Komiji Syncline was formed after the emplacement of lavas and sills in the area, because the descending Miocene strata were folded concordantly with the Shigarami Formation. The Pliocene and Pleistocene strata rest unconformably on the folded strata. The deformation might have progressed during the Pliocene, then slowed down in the Early Pleistocene. Our results suggest that the northwestward motion of the Philippine Sea Plate and the collision of the Tanzawa Block affected not only the South Fossa Magna, but also the North Fossa Magna.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    The @island arc 13 (2004), S. 0 
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1440-1738
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Abstract  Shipboard and shore-based investigation on siliceous and calcareous microfossil biostratigraphy, magneto-stratigraphy and tephrostratigraphy identified numerous datum events from the sedimentary sequences of Sites 1150 and 1151 drilled on the forearc basin of northern Japan by the Ocean Drilling Program Leg 186. Some 83 datum events were selected to construct new age–depth models for the sites. Based on the reliable magneto-stratigraphy from the Pleistocene to the Upper Miocene, which were correlated to the standard geomagnetic polarity timescale, and on excellent records of diatom and radiolarian biostratigraphy throughout the sequences, the shipboard age model was revised. Major revisions referred to stratigraphic position of the Miocene–Pliocene boundary that has been shifted more than 200 m downward in each sequence. The age–depth relations of the forearc sites represent drastic changes in the sedimentation rate—extremely high (40 cm/k.y. on average) in the Early Pliocene and low (less than 2 cm/k.y. on average) in the Middle Miocene—and several hiatuses exist throughout the sequence. The drastic changes can be related mostly to changes in diatom sedimentation and the tectonics of the Japanese Island Arc. Local ages for some foraminiferal, calcareous nannofossil and radiolarian bioevents are estimated from the age–depth models at each site. These newly calibrated bioevents and biozones as well as established diatom biostratigraphy are incorporated into the updated magneto-biochronologic timescale, which will contribute to an improvement in biochronologic accuracy of Neogene sediments in northern Japan and adjacent areas.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...