The Serpukhovian–Bashkirian Amalgamation of Laurussia and the Siberian Continent and Implications for Assembly of Pangea

Abstract

AbstractThe final assembly of Pangea is thought to be marked by the Siberia‐Laurussia amalgamation during the Late Carboniferous–Permian, but there are large uncertainties on the timing of the amalgamation in the previous paleogeographic reconstructions because there are no high‐quality Carboniferous–Permian paleomagnetic data available from the Siberian continent. The Zharma‐Saur area in the junction between the Siberia‐Laurussia amalgamation, involving the Zharma‐Saur arc on the northern margin of the Kazakhstan microcontinent, the South Chinese Altai terrane in the southern margin of the Siberian continent and the Irtysh‐Zaisan suture in between, can provide crucial geological constraints for the assembly of Pangea. In the Zharma‐Saur arc, the Tournaisian–Visean marine sequences are interbedded with thick pillow lavas, which were formed during southward subduction of the Irtysh‐Zaisan Ocean and unconformably covered by the Moscovian terrestrial bimodal volcanic associations and sedimentary successions, in which the basalts are columnar‐jointed in structure and the sandstones also contain the detritus derived from the South Chinese Altai terrane. The Serpukhovian–Bashkirian unconformity was coeval with the transition from the Tournaisian–Visean calc‐alkaline to the Moscovian–Early Permian high alkaline and bimodal volcanism. These dramatic changes in sedimentary environments, provenances and volcanism together indicate the Siberia‐Laurussia amalgamation during the Serpukhovian–Bashkirian and this event was almost simultaneous with the Laurussia‐Gondwana collision and the welding of Laurussia with the Kazakhstan microcontinent, but slightly earlier than the Laurussia‐Tarim collision. Therefore, the final assembly of Pangea could be completed in the Late Carboniferous.