Paleomagnetism of Upper Jurassic basalts from Transbaikalia: new data on the time of closure of the Mongol-Okhotsk Ocean and Mesozoic intraplate tectonics of Central Asia

摘要: The Upper Jurassic basalts (150–160 Ma) described as the Ichetui Formation over territory of Tugnui, Margintui, and Maly Khamar-Daban volcanic structures have been studied paleomagnetically. It is shown that natural remanent magnetization still contains a component which may reflect geomagnetic field direction at beginning Late Jurassic. This supported by reversal conglomerate tests. Calculation mean paleopole gives: Plat = 63.6°, Plong 166.8°, α95 8.5°. These values well coincide with data for Badin from Mogzon depression, lies east study area approximately dates Kimmeridgian-Oxfordian interval At same time, those poles statistically differ European Southeast Asian age. available paleomagnetic suggest Mongol-Okhotsk Ocean was probably open. Since early continental blocks Southeastern Asia Siberian part Eurasian plate had approaching, domain rotating clockwise. Analysis total shows sinistral strike-slip deformations were present not only in southern Siberia but also between Platforms. Thus, Central crust intraplate motions coeval closure are governed clockwise rotation relative to its part.