Magma source and tectonic implications of Miocene Kuzigan alkaline syenite complex in the West Kunlun Orogenic belt, eastern Pamir

Le résumé fourni par la source

Taxkorgan is located in the West Kunlun Orogenic belt in China between the Pamir and Tibetan plateaus, which is very important Fe-Cu polymetallic resource district. The Kuzigan alkaline syenite complex as the largest Cenozoic alkaline complex in the Taxkorgan area. To date, the origin, tectonic setting, and REE mineralization potential of the alkaline complex remain unclear due to the rugged geographical location. This study presents zircon U-Pb age, mineral geochemistry, in-situ trace elements data for the Kuzigan alkaline syenite complex on the Taxkorgan area, which is helpful for further understanding the formation of the mineralization, magma source and tectono-geodynamic setting. In the field, we first discovered the independent REE minerals. (i.e., bastnaesite) in the Kuzigan syenite. Zircon U-Pb dating of ore-bearing syenite and non-mineralization syenite yield two concordant ages of 10.2 ± 0.1 Ma to 10.9 ± 0.1 Ma, form during the Miocene, and indicating their formation are coeval with most REE mineralization in this post–collisional extensional setting. Both the minerals (aegirine–augite and apatite) and syenites (ore-bearing and non-mineralization) exhibit similar enrichments in large-ion lithophile elements (i.e., Sr and Ba) and light REEs, depletion in high-field-strength elements (i.e., Nb) and heavy REEs, and small Eu anomalies. These geochemical and tectonic evolution feature indicate that the Kuzigan alkaline magma source was derived from the lithospheric mantle via a channel within the subduction-related slab during magma ascent that finally formation the Kuzigan alkaline syenite complex, which could lead the REE minerals limited enrichment in this stage.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.