Neoproterozoic‐Early Paleozoic Peri‐Pacific Accretionary Evolution of the Mongolian Collage System: Insights From Geochemical and U‐Pb Zircon Data From the Ordovician Sedimentary Wedge in the Mongolian Altai

Neoproterozoic to early Paleozoic accretionary processes of the Central Asian Orogenic Belt have been evaluated so far mainly using the geology of ophiolites and/or magmatic arcs. Thus, the knowledge of the nature and evolution of associated sedimentary prisms remains fragmentary. We carried out an...

Full description

Saved in:
Bibliographic Details
Published in:Tectonics (Washington, D.C.) D.C.), 2017-11, Vol.36 (11), p.2305-2331
Main Authors: Jiang, Y. D., Schulmann, K., Kröner, A., Sun, M., Lexa, O., Janoušek, V., Buriánek, D., Yuan, C., Hanžl, P.
Format: Article
Language:English
Subjects:
Accretion
Active margin sediments
Active margins
Cambrian
Components
Continental margins
Cratons
Earth Sciences
Ecological succession
Evolution
Geochemistry
Geodynamics
Geological time
Geology
Graywacke
Lead
Magma
Mongolian Altai
Mountains
Neoproterozoic‐early Paleozoic
Ophiolites
Ordovician
Paleozoic
Passive margins
Peri‐Pacific accretion
Precambrian
Sciences of the Universe
Subduction
Subduction zones
Tectonics
Tectonophysics
Turbidite basin
Zircon
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Neoproterozoic to early Paleozoic accretionary processes of the Central Asian Orogenic Belt have been evaluated so far mainly using the geology of ophiolites and/or magmatic arcs. Thus, the knowledge of the nature and evolution of associated sedimentary prisms remains fragmentary. We carried out an integrated geological, geochemical, and zircon U‐Pb geochronological study on a giant Ordovician metasedimentary succession of the Mongolian Altai Mountains. This succession is characterized by dominant terrigenous components mixed with volcanogenic material. It is chemically immature, compositionally analogous to graywacke, and marked by significant input of felsic to intermediate arc components, pointing to an active continental margin depositional setting. Detrital zircon U‐Pb ages suggest a source dominated by products of early Paleozoic magmatism prevailing during the Cambrian‐Ordovician and culminating at circa 500 Ma. We propose that the Ordovician succession forms an “Altai sedimentary wedge,” the evolution of which can be linked to the geodynamics of the margins of the Mongolian Precambrian Zavhan‐Baydrag blocks. This involved subduction reversal from southward subduction of a passive continental margin (Early Cambrian) to the development of the “Ikh‐Mongol Magmatic Arc System” and the giant Altai sedimentary wedge above a north dipping subduction zone (Late Cambrian‐Ordovician). Such a dynamic process resembles the tectonic evolution of the peri‐Pacific accretionary Terra Australis Orogen. A new model reconciling the Baikalian metamorphic belt along the southern Siberian Craton with peri‐Pacific Altai accretionary systems fringing the Mongolian microcontinents is proposed to explain the Cambro‐Ordovician geodynamic evolution of the Mongolian collage system. Key Points The Mongolian Altai represents an Ordovician accretionary wedge riming the active margins of the northerly Precambrian blocks Western margins of Mongolian Precambrian blocks switched from an Early Cambrian passive margin to a Late Cambrian‐Ordovician active one The Mongolian collage system and southern Siberia probably evolved from a peri‐Pacific subduction system in Cambro‐Ordovician
ISSN:0278-7407
1944-9194
DOI:10.1002/2017TC004533