Mesozoic Mo Deposits in Northern North China Craton

Abstract

The North China Craton (NCC) was finally formed at ca. 1850 Ma and then kept its stability and uniformity until the Mesozoic decratonization. After the closure of the Paleo-Asian Ocean in Late Permian and the northernmost Paleo-Tethys Ocean in end-Triassic, the NCC continuously collided with the Siberia Craton to the north and the South China Block to the south, followed by subduction of the Mongol–Okhotsk and Pacific oceanic plates. These significant Mesozoic tectonic events destructed the NCC’s stability and uniformity, and caused intensive hydrothermal mineralization of Mo, Au, Ag, and other metals. The NCC is the most important Mo province in the world, with the Mo deposits being concentrated at the southern and northern margins of NCC. In this contribution, we briefly summarize the geology, geochemistry and isotope ages of the Mo deposits in the northern NCC (NNCC), overview the progresses in understanding the ore geneses and tectonic settings, and setup a linkage between the mineralization and orogenies which resulted in the decratonization of the NCC. All the Mo-only or Mo-dominated deposits were formed after the closure of the Paleo-Asian Ocean, and in a series of pulses around 250–200, 200–160, 160–130 and <130 Ma (130–100 Ma). Main genetic types are porphyries (including breccia pipes), skarns and quartz veins, with the porphyry systems being predominant. The porphyry Mo deposits can be further subdivided into three subtypes, i.e., collision- or Dabie-, rift- or Climax-, and subduction- or Endako-types. The Mo deposits aged 250–200-Ma and 200–160-Ma belong to collision-type and have been formed in syn- to post-collisional tectonic setting. The 160–130-Ma Mo mineralization mainly occurs in the central NNCC and are predominated by the Climax-type porphyry Mo systems, which resulted from a back-arc rift related to southward subduction of the Mongol–Okhotsk oceanic plate. The 130–100-Ma deposit belongs to Endako-type and are only located in the eastern part of the northern NCC, which must be related to the westward subduction of the Paleo-Pacific oceanic plate. As shown by the porphyry Mo deposits in NNCC, the mineral systems are a powerful indicator of tectonic settings and associated evolutionary trends.