: Located on the northeast margin of the Qiangtang terrane between the Jinshajiang suture zone and Bangonghu‐Nujiang suture zone, the Dongmozhazhua and Mohailaheng Pb‐Zn deposits in the Yushu area of Qinghai Province are representative Pb‐Zn deposits of the Pb‐Zn‐Cu polymetallic mineralization belt in the northern part of the Nujiang‐Lancangjiang‐Jinshajiang area, which are in the front belt of the Yushu thrust nappe system. The formed environments of these two deposits are different from those of sediment‐hosted base metal deposits elsewhere in the world. The authors hold that they were formed during the Indian‐Asian continental collision and developed within the fold‐thrust belt combined with thrust and strike‐slip‐related Cenozoic basins in the interior of the collisional zone. Studying on the metallogenic epochs of these two deposits is helpful to the understanding of ore‐forming regularity of the regional Pb‐Zn‐Cu mineralization belt and also to the search for new deposits in this region. The age of the Dongmozhazhua deposit has been determined by the Rb‐Sr isochron method for sphalerite residues, whereas the age of the Mohailaheng deposit has been determined by the Rb‐Sr isochron method for sphalerite residues and the Sm‐Nd isochron method for fluorite. The age of the Dongmozhazhua deposit is 35.0±0.0 Ma ((87Sr/86Sr)0=0.708807) for sphalerite residues. The age of the Mohailaheng deposit is 32.2±0.4 Ma ((87Sr/86Sr)0=0.708514) for sphalerite residues and 31.8±0.3 Ma ((143Nd/144Nd)0=0.512362) for fluorite with an average of 32.0 Ma. Together with the regional geological setting during mineralization, a possible tectonic model for metallogeny of the Dongmozhazhua and Mohailaheng Pb‐Zn deposits has been established. These two ages are close to the ages of the Pb‐Zn deposits in the Lanping and Tuotuohe basins, indicating that it is possible that the narrow 1000‐kilometer‐long belt controlled by a thrust nappe system on the eastern and northern margins of the Tibetan plateau could be a giant Pb‐Zn mineralized belt.

The Yuqia uranium deposit is a newly discovered sandstone-type uranium deposit in the northern margin of the Qaidam Basin. Concerning the sources of sediment in the basin, most scholars have focused on the study of Cenozoic sediment sources in the northern part of the basin, rather than on the study of Jurassic provenance and its implications for uranium mineralization. In this paper, the Jurassic sandstones in the area were selected for petrography, petrogeochemistry and electron microprobe analysis (EPMA), and the significance of sedimentary provenance and uranium metallogeny were further discussed, based on the previous data of detrital zircon chronology. It is reported here for the first time that coffinite and pitchblende are the main contributors. Independent uranium minerals in the region mainly occur in strawberry pyrite, xenotime, and margins or of quartz. The rocks in the source area, Jurassic sandstones, were mainly formed under the tectonic setting of the active continental margin; however, the sediments are mainly derived from the Indosinian and Paleozoic granitoids exposed in the northern margin of the Qaidam Basin. The uranium-rich granites in the source area led to the preconcentration of uranium in the sandstone of the target layer, and the uranium was brought into the ore-bearing target layer through uranium-bearing oxygenated water. The reduction reaction occurred under the action of reducing matter, and finally, the U6+ was reduced to U4+ in the formation of coffinite and pitchblende.

The origin of giant rare earth element (REE)‐rich phosphorus deposits related to ultramafic rocks is unclear. To characterize the genetic linkage between ultramafic rocks and P–REE mineralization, we investigated the whole‐rock geochemistry, geochronology and Hf isotopic compositions, along with previously published data of barren and ore‐bearing clinopyroxenites from the giant Shangzhuang REE‐rich apatite deposit (containing about 51.1 million tonnes of P2O5 and 157,400 tonnes of REEs) in the Lajishan suture, Western China. The P–REE ores and barren biotite clinopyroxenites are composed predominantly of clinopyroxene and biotite, with high levels of apatite, amphibole, allanite, sulfide and oxide minerals in the ore‐bearing samples. Zircon and allanite U–Pb ages for the barren and ore‐bearing clinopyroxenites indicate they were formed between 467 and 465 Ma. The barren and ore‐bearing samples are characterized by high CaO and low SiO2 contents, as well as similar Hf isotope ratios (εHf[t]: +3.4 to +7.7), indicating that they represent an ultramafic magma system and have been derived from a similar source. They are enriched in light REEs and depleted in Nb–Ta–Zr–Hf–Ti, similar to arc‐related lavas found worldwide. The weakly evolved barren samples have high Ba/La, Rb/Y and Dy/Yb values, and their ages are coeval with calc‐alkaline granitic plutons in the belt, which postdate the formation of the Lajishan ophiolite by ~30 myr. This suggests that the primary magma originated from garnet peridotite mantle modified by subducted Proto‐Tethys oceanic crust‐derived fluids in an arc setting. The presence of apatite intergrowth with cumulus clinopyroxene without alteration features indicates that the deposit has a magmatic origin. The ore‐bearing clinopyroxenite contains higher contents of P, REEs, and high‐field‐strength elements than the barren clinopyroxenite, which could be attributed to the in situ accumulation of apatite and allanite in the residual magma. Thus, the formation of the P‐dominated orebodies results from phosphate saturation due to the extensive fractionation crystallization of clinopyroxene and biotite during magmatic evolution. REEs were primarily enriched in the late‐stage melt, which was compatible with apatite and allanite. We propose that the formation of the Shangzhuang REE‐rich apatite deposit can be attributed to a simple differentiation of ultramafic melts in an evolved magmatic system.