Geochronology and geochemistry of the Wulanwusu P-Fe deposit, northern North China Craton: Evidence for a genetic link to the Paleoproterozoic anorthosite-mangerite-charnockite-granite (AMCG) suite

• Neoarchean metamorphic series-hosted P-Fe mineralization constrained at 1730 ± 6 Ma. • The P-Fe mineralization is igneous rather than sedimentary-metamorphic. • Parental magma was derived from an enriched subcontinental lithospheric mantle. • A genetic link established with the P-Fe ores and the Paleoproterozoic AMCG suite. Phosphate deposits of both sedimentary and igneous origins are the most important sources of phosphorus in the world. Neoarchean metamorphic series-hosted apatite-magnetite deposits in the northern North China Craton (NCC) are important sources of P and Fe. However, the genesis of some deposits remains controversial, as they are proposed to have formed through sedimentary-metamorphic processes in the phosphorus-deficient Neoarchean environment. The Wulanwusu P-Fe deposit in the Jianping area is a typical example, with the P-Fe mineralization typically composed of plagioclase, amphibole, biotite, apatite and Fe-Ti oxides. This study aims to constrain the geological controls on P-Fe mineralization through petrographic, geochronological, and geochemical analyses of P-Fe ores. Zircon U-Pb geochronology yielded a weighted crystallization age at 1730 ± 6 Ma, precisely constraining the timing of mineralization to the late Paleoproterozoic. Petrographic observations, whole-rock and apatite geochemistry collectively indicate that the mineralization is associated with a mafic magmatic event, supporting its classification as a late Paleoproterozoic igneous P-Fe deposit. Our results clearly rule out a previously suggested link between P-Fe mineralization and metamorphosed Neoarchean volcano-sedimentary rocks. The Nd-Hf isotopic compositions suggest that the parental magma was derived from an enriched subcontinental lithospheric mantle source. Combined with geochronological and geochemical evidence, these results indicate that the formation of the Wulanwusu P-Fe deposit is linked to the late Paleoproterozoic AMCG suite magmatism in the northern NCC and occurred in a post-collisional extensional stage following the convergence of the eastern and western blocks of the NCC.