Petrogenesis and metallogenesis of the Kawuliuke Fe-P-Ti oxide-rich intrusive complex in the Kuluketage Block, northeastern Tarim Craton

Abstract

The Kawuliuke Fe-P-Ti oxide-rich intrusive complex is one of the largest layered mafic–ultramafic complexes associated with Fe-P-(Ti) oxide deposits in the Kuluketage Block, northeastern Tarim Craton, NW China. Here, based on new field observations, whole-rock trace element, radiometric dating analyses as well as Sr-Nd-Hf isotopes we propose a non-cogenetic origin of the parental magmas of the mafic–ultramafic rocks and syenite in the Kawuliuke intrusive complex (KIC), both of which formed synchronously at circa 808 Ma.Geochemical characteristics and Sr-Nd-Hf-S isotopes ((87Sr/86Sr)i = 0.70437–0.70560; εNd(t) = -2.60 to −7.15; εHf(t) = -1.3 to −10.0; δ34S = -2.98 ‰ to + 2.36 ‰), in combination with minerals composition and previous research, strongly indicate that the mafic–ultramafic rocks of the KIC formed via extensive crystal fractionation/cumulation of a tholeiitic magma, possibly derived from partial melting of an enriched subcontinental lithospheric mantle previously modified by slab-released fluids in a continental rift setting. The Kawuliuke syenite, meanwhile, is interpreted as generated by the emplacement of syenitic melts from the differentiation of newly coeval underplating basaltic magmas at depth based on lines of evidence from petrography, geochemical signatures and Sr-Nd-Hf isotopes. Our newly presented enriched Sr-Nd-Hf isotopic signatures, together with previous research, suggest that the enriched subcontinental lithospheric mantle could be metasomatized by asthenosphere mantle melts in different degrees. We further show the Kawuliuke clinopyroxenite-related apatite-rich oxide ores were the products of normal fractional crystallization/cumulation of H2O-Fe-P-Ti enriched residual magma in high oxygen fugacity condition, which experienced high differentiation. The tempo-spatial relationships of the KIC and other regional coeval mafic rocks jointly suggest that the KIC was most likely formed in response to the proposed mid-Neoproterozoic mantle plume in Tarim Craton, which likely induced partial malting of, and likely mixed with, the metasomatized subcontinental lithospheric mantle, to form the KIC with clinopyroxenite-related Fe-P-Ti oxide mineralization.