HR: 0800h
AN: GP11A-0004    [Abstracts]
TI: Paleomagnetism of Middle and Upper Paleozoic rocks from West and Central Kazakhstan.
AU: * Alexyutin, M
EM: maxalex@geophysik.uni-meunchen.de
AF: Department of Earth and Environmental Sciences Geophysics Munich University, Theresienstr, 41 , Munich, 80333 Germany
AU: * Alexyutin, M
EM: maxalex@geophysik.uni-meunchen.de
AF: Geological Institute, Russian Academy of Sciences, Pyzhevsky,7, Moscow, 119017 Russian Federation
AU: Alexeiev, D
EM: dvalexeiev@mtu-net.ru
AF: Institute of Oceanology, Russian Academy of Sciences, Nakhimovsky Prospekt,36, Moscow, 117997 Russian Federation
AU: Bachtadse, V
EM: valerian@geophysik.uni-muenchen.de
AF: Department of Earth and Environmental Sciences Geophysics Munich University, Theresienstr, 41 , Munich, 80333 Germany
AB: Kazakhstan occupies a central position within the mosaic of continental blocks of Central Asia, which were amalgamated and subsequently welded to the eastern margin of Europe. The understanding of the tectonic evolution of this area during Carboniferous and Permian times is crucial for the understanding of the tectonic processes to the east of the Urals as well as for the understanding of the geological history of Eurasia as a whole during the Paleozoic. Here, we present results of detailed paleomagnetic investigations in Central Kazakhstan.. Middle and Upper Paleozoic red beds were sampled in several localities in the western part of Central Kazakhstan, including: a) the Archaly formation (Lower Permain) in the North of the Teniz basin, b) the Vladimirskaya formation (Upper Carboniferous (?)) in the north of the Teniz basin, and c) the Dzhezkazgan formation (Upper Carboniferous) to the North and East of the town of Dzhezkazgan. The mid Devonian to upper Permian rocks in the area are deformed conformably, and are exposed in simple open folds. Based on geological evidence, the age of deformation has been constrained to be latest Permian to early Mesozoic (pre Cretaceous). Secondary components of magnetization, identified in the Archaly (Lower Permian) and Vladimirskaya (Upper Carboniferous?) formations yield a mean direction of D=33.6 °, I=70.2°, k=43.3, α95=10.3°. Unfortunately, however, the age of this remagnetization cannot be constrained precisely and can range from the Early Mesozoic to present day. Two components, carried either by magnetite (component A) or by hematite (component B) were identified in red colored rocks of the Upper Carboniferous Dzhezkazgan formation in the North and East of the town of Dzhezkazgan. Both components pass the fold test and yield a bedding-corrected site mean direction of D=279.5°, I=-42.6°, k=47.1, α95 =11.3°. Based on the age of deformation the age of magnetization can be constrained to be pre Permian to early Mesozoic in age. This result indicates some clockwise rotation of the studied unit with respect to Baltica and Siberia since Late Carboniferous to Late Permian (Early Mesozoic) time. However, this rotation is very likely to be related to local strike-slip faults. It can be speculated that paleomagnetic sampling of late Paleozoic rocks in Kazakhstan is biased towards sections which are stronger deformed and display enough variety in structural attitude. These sections, however, are very likely to be close to or within strike-slip zones and might have suffered local rotations. Therefore more data from the undeformed regions of Kazakhstan is in urgent demand for robust geodynamic models for Transuralian Eurasia.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005