Neoproterozoic–early Paleozoic evolution of the southern Central Asian Orogenic Belt: Constraints from eclogites in the Beishan Orogenic Belt (NW China)

Abstract

<p>Eclogites provide important constraints on the processes of plate subduction, collision, and the overall tectonic evolution of orogens. The Gubaoquan eclogite is the only one identified in the Beishan Orogenic Belt, which constitutes the southernmost part of the Central Asian Orogenic Belt. U-Pb dating of the eclogite indicates a Neoproterozoic metamorphic age of 887 ± 7 Ma and an Ordovician age of 461 ± 15 Ma for the eclogite-facies metamorphism. Multi-proxy (zircon, monazite, rutile, and apatite) U/Th-Pb geochronology and trace element geochemistry reveal that they have experienced multiple tectonothermal events in the Neoproterozoic and Paleozoic. The protolith of the Gubaoquan eclogite is of continental origin, and along with the extensive distribution of the Neoproterozoic arc-related rocks probably formed near the periphery of Rodinia. Given the continental setting of the protolith of the Gubaoquan eclogite, we suggest that eclogite-facies metamorphism at ca. 461 Ma was due to subduction under the Shuangyingshan-Huaniushan arc, which is manifested as an arc-continental collision process.<br></p>