Neoproterozoic subduction-related basaltic magmatism in the northern margin of the Tarim Craton: Implications for Rodinia reconstruction

• Neoproterozoic mafic-ultramafic rocks in N. Tarim were not produced by mantle plume.
• The temporal-spatial distribution of these rocks does not show a hotspot track.
• Whole rock chemical and isotopic compositions indicate that they are arc cumulates.
• Northern Tarim was part of the Neoproterozoic Circum-Rodinia Subduction System.

A single mantle plume model for the Neoproterozoic mafic-ultramafic intrusive rocks (760–820 Ma) in the northern rim of the Tarim Craton (Kuluketage, Xinjiang, China) is not supported by the protracted nature of magma emplacement that does not show a hot spot track, and whole-rock trace element compositions that clearly show arc signatures. New and previous zircon U-Pb age data reveal an age difference of up to 11 myr for a single mafic-ultramafic intrusive complex and an age difference of up to 32 myr for two mafic-ultramafic intrusive complexes separated by only ∼10 km. Such age differences are more than 2–5 times the analytical uncertainties. No major faults are present between the two intrusive complexes with different ages so their original distance is still well preserved. In addition, the age change of the mafic-ultramafic intrusive rocks in the region occurs in different directions. The temporal-spatial distribution of these rocks can be well explained by subduction-related magmatism that can last for a very long period of time at the same location. The protracted Neoproterozoic mafic-ultramafic intrusive rocks in the Kuluketage district are all characterized by moderate light rare earth element enrichments, pronounced negative Nb-Ta anomalies and low εNd(t) values (1 to −11) coupled with elevated initial 87Sr/86Sr ratios (0.706–0.71), which are consistent with the products of arc basalts contaminated with crustal materials. The results from this study support the notion that the northern margin of the Tarim Craton was part of the Neoproterozoic Circum-Rodinia Subduction System.