A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia)

0487425 - GLÚ 2018 RIV NL eng J - Journal Article
Soejono, I. - Buriánek, D. - Janoušek, V. - Svojtka, Martin - Čáp, P. - Erban, V. - Ganpurev, D.
A reworked Lake Zone margin: Chronological and geochemical constraints from the Ordovician arc-related basement of the Hovd Zone (western Mongolia).
Lithos. 294/295, December (2017), s. 112-132. ISSN 0024-4937. E-ISSN 1872-6143
Institutional support: RVO:67985831
Keywords : Ordovician magmatic arc * Mid-Silurian intra-plate magmatism * Hovd Zone * Reworked Lake Zone
OECD category: Geology
Impact factor: 3.857, year: 2017

The Mongolian tract of the Central Asian Orogenic Belt (CAOB) are still poorly constrained. This brings much uncertainty in understanding of the orogeny configuration and the complete accretionary history. Results of our field work, new U–Pb zircon ages and whole-rock geochemical data suggest an existence of two separate magmatic events within the evolution of the Khuurai Tsenkher Gol Complex. Early to Mid-Ordovician (476 ± 5 Ma and 467 ± 4 Ma protoliths) normal- to high-K calc-alkaline orthogneisses, metadiorites and metagabbros predominate over Mid-Silurian (430 ± 3 Ma) tholeiitic–mildly alkaline quartz monzodiorites. Whereas the geochemical signature of the former suite unequivocally demonstrates its magmatic-arc origin, that of the latter quartz monzodiorite suggests an intra-plate setting. As shown by Sr–Nd isotopic data, the older arc-related magmas were derived from depleted mantle and/or were generated by partial melting of juvenile metabasic crust. Detrital zircon age populations of the metasedimentary rocks together with geochemical signatures of the associated amphibolites imply that the Bij Group was a volcano-sedimentary sequence, formed probably in the associated fore-arc wedge basin.Moreover, our data argue for an identical provenance of the Altai and Hovd domains, overall westward sediment transport during the Early Palaeozoic and the east-dipping subduction polarity.
Permanent Link: http://hdl.handle.net/11104/0282105