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Detailed Reference Information |
McWilliams, M., Sharps, R. and Cox, A. (1990). A Devonian paleomagnetic pole from red beds of the Tarim Block, China. Journal of Geophysical Research 95: doi: 10.1029/90JB01373. issn: 0148-0227. |
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We present new Devonian paleomagnetic results from 59 sites in three stratigraphic sections exposed on the northwestern margin of the Tarim Block. At one section, 1998 m of red sandstone is continuously exposed; the other two sections can be correlated with the first on both magnetostratigraphic and lithologic grounds. Progressive thermal demagnetization reveals three characteristic magnetizations. One is a Late Permian overprint which is isolated below 578 ¿C at sites near contacts with Late Permian dikes. The other two components are approximately antipodal, have a much higher unblocking temperature than the overprint, and are directionally distinct from the Late Permian overprint. We believe that these are characteristic Devonian magnetizations. Within the continuous 1998 m section, our results denote a 395 m reversed polarity zone overlying a 1603 m normal polarity zone. One reversed event is recorded at the base of the section. A paleomagnetic pole calculated by averaging results from 47 normal and reversed sites lies at λp=16.5 ¿N, ϕp=165.0 ¿E, K=25, and A95=4.3¿. This pole is statistically distinct from a previously reported Late Devonian pole for Tarim. On the basis of field geologic and rock magnetic studies, we believe that the previously reported pole, in addition to results from one of our three sections, reflects at least partial contamination in the form of a thermal overprint caused by Late Permian igneous activity. An analysis of Devonian to Late Carboniferous polar wander suggests that the Tarim BLock was attached to a subducting plate, and moved northward and rotated clockwise during the late Paleozoic. Comparison of the Devonian paleolatitudes of SIberian, Kazakhstan, Tarim and South China Blocks indicates that both the Tarim and South China Blocks were located in equatorial regions and were far south of the northern Angaran plate (Siberia and Kazakhstan). ¿ American Geophysical Union 1990 |
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Abstract |
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Keywords
Geomagnetism and Paleomagnetism, Paleomagnetism applied to tectonics (regional, global), Information Related to Geologic Time, Paleozoic, Information Related to Geographic Region, Asia |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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