Microplates vs Siberian Craton, History of the Patom Belt
Abstract
The Central Asian Orogenic Belt (CAOB) also known as the Altaides is supposed to result from the accretion of volcanic arcs and microcontinents against the Siberian craton. An interdisciplinary approach including stratigraphic and structural study and a field survey led in the Patom area allows us to precise the geodynamic history of the region. The observed sedimentary succession confirms the existence of a passive margin setting in the Late Riphean (around 900 Ma), followed during the Vendian (650-600 Ma) by the obduction of the Baikal-Muya ophiolites belt and a foredeep inversion. This first accretion stage does not induce significant deformations and rather appears as a soft-docking event. Then, a period of relative tectonic quiescence is recorded until the main collision stage (post Devonian) attested by new age constraints. The regional geodynamics is thus marked by a slow evolution with very long stable periods of more than 250 Ma between "convergent pulses". Moreover, we observe limited deformation and low shortening rate which seem to be characteristic of a pericratonic context and we conclude that accretionary orogens appear not mature. On another hand, apatite fission tracks analysis were carried out on samples from the Siberian platform, Patom range and Cenozoic Baikal rift basins. These new data reveal relative vertical movements and clearly show a late Jurassic - early Cretaceous tectonic reactivation of ancient Paleozoic boundaries. These results evidence successive stages of tectonic collage and terranes accretion, from Neoproterozoic to Mesozoic times, and raise the question of stabilization or cratonization of accretionary orogens and microplates jigsaws.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.T11B1858D
- Keywords:
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- 8015 Local crustal structure;
- 8103 Continental cratons;
- 9320 Asia;
- 9614 Paleozoic;
- 9622 Proterozoic