A western Amazonian affinity in the periphery of the Nuna supercontinent for Mesoproterozoic basements in the southern Central Asian orogenic belt

Abstract

<p>The Central Asian orogenic belt (CAOB) is one of the largest Phanerozoic accretionary orogens in Earth's history with myriad metal deposits. Mesoproterozoic basements are sporadically preserved along the southern CAOB. Their tectonic affinity remains controversial, which hampers us from better understanding the basic architecture and Phanerozoic tectonic evolution of the CAOB. This study identified Mesoproterozoic sedimentary rocks in the northeastern Altyn Tagh, southeast of the Tarim craton, from which detrital zircons have remarkable U-Pb age peaks at ca. 1.7 and 1.4 Ga and highly variable εHf(t) values from −9 to + 14, resembling those from the southern CAOB. Based on provenance tracing and comparison of available geological records, the Mesoproterozoic basements in the southern CAOB show an affinity with the Rondonian-San Ignacio Province in western Amazonia associated with the peripheral accretion of the Nuna supercontinent and were subsequently fragmented and dispersed over 3000 km in distance. Predominately juvenile 1.8–1.3 Ga magmatic rocks with a scarcity of ca. 1.4 Ga ones in southern Laurentia and southwestern Baltica preclude a possible link. Likewise, a paucity of ca. 1.4 Ga zircons and incomparable isotope signatures in North China, India, and Australia challenge their affinities with the CAOB's basements. This work focuses on the tectonic attribution of the Mesoproterozoic basements in the southern CAOB and highlights the energetic Mesoproterozoic era, during which the accretionary orogeny was intensely operative along the periphery of the Nuna supercontinent.</p>