ISSN:
1573-9708
Keywords:
Cimmerian
;
paleomagnetism
;
Tethys
;
Turkmenistan
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
Notes:
Abstract Calc-alkaline volcanic deposits from the south-west of the Turan plate, near the city of Turkmenbasi (40°00'N, 52°58&E) in Turkmenistan, were studied paleomagnetically. These rocks have been affected by a greenschist-facies metamorphism, possibly of regional extent, that has been K/Ar-dated as 200 to 227 Ma old. A low-blocking-temperature component (D = 349°, I = 64°), close to the present field direction and probably of viscous or recent chemical origin, was isolated by a negative fold test at three sites. The mean direction of a high-blocking-temperature component isolated at 15 sites, mainly carried by magnetite, is scattered before and after tectonic correction and is therefore difficult to interpret. A group of seven sites with low inclinations before and after tectonic correction was isolated. The mean inclination of these sites (31 ± 8°), syn-folding or post-folding, corresponds to a paleolatitude of 17 ± 8° which is lower than the conventional Eurasian paleolatitudes for post-Permian times. The paleomagnetic data from the Turan and Iran plates constrain this low paleolatitude to the Late Triassic and Jurassic period. This requires a shortening of at least 7° between the Turan plate and Eurasia during this time.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1003129028277
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