The origin of the Baydaric microcontinent, Mongolia: Constraints from paleomagnetism and geochronology Natalia M. Levashova a, ⁎, Valery M. Kalugin b , Anatoly S. Gibsher b , Jessica Yff c , Alexander B. Ryabinin b , Joseph G. Meert c , Shawn J. Malone c a Geological Institute, Academy of Science of Russia, Pyzhevsky Lane, 7, Moscow 109017, Russia b Institute of Geology and Mineralogy, Siberian Branch of the Academy of Science of Russia, Koptyug Pr. 3, Novosibirsk 630090, Russia c Department of Geological Sciences, 274 Williamson Hall, Gainesville, FL 32611, USA abstract article info Article history: Received 9 April 2009 Received in revised form 28 October 2009 Accepted 29 January 2010 Available online xxxx Keywords: Central Asia orogenic belt Geochronology Paleomagnetism Mongolia Existing views on the tectonic evolution of the Central Asian orogenic belt (CAOB) are highly controversial and the Neoproterozoic to Cambrian stages of this evolution remain the most enigmatic. However, the views on the Paleozoic evolution of the CAOB crucially depend on these early stages, as different choices of the starting point lead to very dissimilar Paleozoic reconstructions. In this context numerous microcontinents with the Precambrian basement that are included in the mosaic structure of Kazakhstan, Tien Shan, Altai and Mongolia are of particular interest. We undertook a paleomagnetic, geochemical and geochronological study of the Neoproterozoic volcanics from one of these units — the Baydaric microcontinent in Central Mongolia. According to U–Pb (laser ablation) dating the age of the studied Dzabkhan Volcanics is about 770–805 Ma. Thermal demagnetization revealed that most of the studied samples retained a pre-tilting component, whose primary origin is supported by a conglomerate test. These new data, together with available geological information allow us to conclude that about 770–800 Ma ago the Baydaric domain was located at a latitude of 47 -12 + 16 ° N and belonged to one of the following plates: India, South China, Tarim or Australia. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Eurasia comprises several major blocks with Precambrian base- ment, separated by younger mobile belts of Phanerozoic age (Fig. 1a). It can be argued that Eurasia represents a superb natural laboratory for elucidating continental amalgamation leading to the formation of a future supercontinent. The Alpine and Central Asian orogenic belts are the largest in Eurasia. Whereas the former was the locus of Eurasia growth in the Mesozoic and Cenozoic, the latter played the same role through the Neoproterozoic and Paleozoic. The Central Asian orogenic belt (CAOB) stretches from the Urals to Kazakhstan and Tien Shan to Altai and Mongolia to the Pacific. The central part of the CAOB is located between the European, Siberian, North China, and Tarim platforms (Fig. 1a), and has the most complex tectonic history. Unlike typical inter-continental or peri-continental linear orogenic belts like the Urals, Andes, Appalachians, etc., no prevailing structural trend is observed here. Numerous microcontinents with Precambrian basement and late Neoproterozoic–Early Paleozoic terrigenous clastic or carbonate cover are tectonically juxtaposed with late Neoproterozoic–Early Paleozoic subduction-related volcanic com- plexes, accretionary wedges and flysch sequences and form mosaic structure. Existing views on the tectonic evolution of the CAOB are highly controversial. Thus, one can find a slowly evolving flotilla of micro- continents and island arcs (Mossakovsky et al., 1993; Didenko et al., 1994; Filipova et al., 2001), or a gradually coiling serpentine island arc (Şengör and Natal'in, 1996; Yakubchuk et al., 2001, 2002), or an array of larger blocks that consumed surrounding oceans according to models that change from author to author (Puchkov, 2000; Stampfli and Borel, 2002). The co-existence of so many dissimilar models strongly indicates that we lack even first-order knowledge about the paleogeography and kinematics of the CAOB constituents. It comes as no surprise that the Neoproterozoic–Cambrian stages of CAOB tectonic evolution remain most enigmatic and controversial. However, our views on the Paleozoic evolution of the CAOB crucially depend on these early stages, as different choices of the starting point lead to very dissimilar Paleozoic reconstructions. Two parameters, which vary widely from one model to another, seem to be of major importance: the relative position of Baltica and Siberia in the Neoproterozoic–Cambrian and the origin and subsequent kinematics of Precambrian microcontinents, included in the CAOB. The first problem is definitely beyond the scope of this study, whereas the origin and subsequent kinematics of the microcontinents may provide insights into early history of the Central Asian orogenic belt and in turn impose strong constraints on general style of its tectonic evolution. Tectonophysics xxx (2010) xxx–xxx ⁎ Corresponding author. E-mail address: namile2007@rambler.ru (N.M. Levashova). TECTO-124844; No of Pages 15 0040-1951/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.tecto.2010.01.012 Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto ARTICLE IN PRESS Please cite this article as: Levashova, N.M., et al., The origin of the Baydaric microcontinent, Mongolia: Constraints from paleomagnetism and geochronology, Tectonophysics (2010), doi:10.1016/j.tecto.2010.01.012