Metallogenic Series Related to Permian Mafic Complex in North Xinjiang: Post‐collisional Stage or Mantle Plume Result?

AbstractThere are four deposit types related to a Permian mafic complex in northern Xinjiang, i.e., copper‐nickel sulfide deposit, vanadic titanomagnetite deposit, magnetite (‐cobalt) deposit and Cu‐Ni‐VTiFe composite deposit. The deposits are distributed spanning tectonic units with close and consecutive metallogenic ages. A transitional deposit type can occur among the end‐member deposits. Trace elements of host rocks show that they can derive from similar source area. Hence, they constitute a particular metallogenic series related to a mafic‐ultramafic complex that is also a symbol series of the post‐collisional stage of the Central Asia Metallogenic Province (CAMP). The metallogenic ages of the series are between 260 Ma and 300 Ma throughout the Permian. Unlike mineralization from a mantle plume, the metallogenic period of this series spans at least 40 Ma. Compared with related deposits of the Emeishan mantle plume, the North Xinjiang series has a similar ore‐forming element assemblage but has preferably developed Cu‐Ni sulfide deposits rather than vanadic titanomagnetite deposits. In concomitance with this series, North Xinjiang area has developed a set of syntectonic Au‐Cu‐Mo metallogenic series related to a felsic volcanic‐intrusive complex, which might indicate that there is no direct relationship with mantle plume activity. From early to late, i.e., the sequence of copper‐nickel sulfide to magnetite (‐cobalt) to vanadic titanomagnetite deposit, the host rock series evolves from mafic‐ultramafic and tholeiite series to mafic and alkalic series, the ΣREE content tends to increase with increasing of REE fractionation, and some of the trace elements (particularly LIL) also show an increasing tendency. The above evolutionary regularity possibly reflects a course where the magma source deepens and thermal interface moves down, energy gradually exhausts, and neo‐continental crust forming in the post‐collision stage tends to stabilize.