HR: 1340h
AN: GP43C-1487    [Abstracts]
TI: Paleomagnetic and Geochronologic Data from Central Asia: Inferences for Early Paleozoic Tectonic Evolution and Timing of Worldwide Glacial Events
AU: * Gregory, L C
EM: lalaura@ufl.edu
AF: University of Florida Geological Sciences, 241 Williamson Hall, Gainesville, FL 32611, United States
AU: Meert, J G
EM: jmeert@ufl.edu
AF: University of Florida Geological Sciences, 241 Williamson Hall, Gainesville, FL 32611, United States
AU: Levashova, N
EM: mibazh@mail.ru
AF: Geological Institute, Russian Academy of Sciences, Pyzhevsky Lane, 7, Moscow, 119017, Russian Federation
AU: Grice, W C
EM: wgrice@ufl.edu
AF: University of Florida Geological Sciences, 241 Williamson Hall, Gainesville, FL 32611, United States
AU: Gibsher, A
EM: gib@uiggm.nsc.ru
AF: Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Koptyug Pr. 3, Novosibirsk, 630090, Russian Federation
AU: Rybanin, A
EM: gib@uiggm.nsc.ru
AF: Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Koptyug Pr. 3, Novosibirsk, 630090, Russian Federation
AB: The Neoproterozoic to early Paleozoic Ural-Mongol belt that runs through Central Asia is crucial for determining the enigmatic amalgamation of microcontinents that make up the Eurasian subcontinent. Two unique models have been proposed for the evolution of Ural-Mongol belt. One involves a complex assemblage of cratonic blocks that have collided and rifted apart during diachronous opening and closing of Neoproterozoic to Devonian aged ocean basins. The opposing model of Sengor and Natal"in proposes a long-standing volcanic arc system that connected Central Asian blocks with the Baltica continent. The Aktau-Mointy and Dzabkhan microcontinents in Kazakhstan and Central Mongolia make up the central section of the Ural-Mongol belt, and both contain glacial sequences characteristic of the hypothesized snowball earth event. These worldwide glaciations are currently under considerable debate, and paleomagnetic data from these microcontients are a useful contribution to the snowball controversy. We have sampled volcanic and sedimentary sequences in Central Mongolia, Kazakhstan and Kyrgyzstan for paleomagnetic and geochronologic study. U-Pb data, 13C curves and abundant fossil records place age constraints on sequences that contain glacial deposits of the hypothesized snowball earth events. Carbonates in the Zavkhan Basin in Mongolia are likely remagnetized, but fossil evidence within the sequence suggests a readjusted age control on two glacial events that were previously labeled as Sturtian and Marinoan. U-Pb ages from both Kazakhstan and Mongolian volcanic sequences imply a similar evolution history of the areas as part of the Ural-Mongol fold belt, and these ages paired with paleomagnetic and 13C records have important tectonic implications. We will present these data in order to place better constraints on the Precambrian to early Paleozoic tectonic evolution of Central Asia and the timing of glacial events recorded in the area.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1599 General or miscellaneous
DE: 8103 Continental cratons
DE: 8157 Plate motions: past (3040)
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting