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| Titel |
Paleomagnetic determination of paleolatitude and rotation of Bering Island (Komandorsky Islands) Russia: comparison with rotations in the Aleutian Islands and Kamchatka |
| VerfasserIn |
P. S. Minyuk, D. B. Stone |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1868-4556
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| Digitales Dokument |
URL |
| Erschienen |
In: Geology, geophysics and tectonics of Northeastern Russia: a tribute to Leonid Parfenov ; Nr. 4 (2009-09-17), S.329-348 |
| Datensatznummer |
250001455
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| Publikation (Nr.) |
 copernicus.org/smsps-4-329-2009.pdf |
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| Zusammenfassung |
| A paleomagnetic study was carried out on Paleogene sedimentary rocks from
Bering Island, Komandorsky islands, located at the far western end of the
Aleutian Island Arc. The age of these sediments has been debated at length,
but the combination of magnetostratigraphy with the fossil record indicates
that the base of the section is of early Eocene (approximately 55 Ma) and
the top latest Eocene age. Paleomagnetic data were obtained from 260 samples
from 60 individual bedding units. The combined data show a clockwise rotation
R=26.3°±8.5°, F=8.1°±2.5° with respect to
the North American Plate and R=38°±8.8°,
F=8.7°±2.7° with respect to the Eurasian Plate. They also
show a shallowing of the inclination which yields a paleolatitude of
53°, 12° south of its expected latitude. The shallowing may
have a component due to compaction, but the wide variation in sampled
lithologies, combined with internal consistency of the data set, would argue
against the shallowing being significant. To compare these data with other
Aleutian Arc data we compiled a comprehensive survey of all available data
sets. Out of these we selected four islands for which the data passed basic
reliability criteria, namely Umnak, Amlia, Amchitka and Medny islands. All
four showed significant clockwise rotation with respect to both North
American and Eurasian polar wander paths. Several mechanisms can generate the
observed rotation, ranging from block rotation driven by oblique relative
motion of the Pacific plate, through lateral transport along the curve of the
arc, to whole-arc rotation about its eastern end. The distribution and age
spread of the rotation data are insufficient to discriminate between
mechanisms, but it seems likely that different mechanism may have operated at
different times and in different locations. |
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