Formation of the Nephrite Deposit With Five Mineral Assemblage Zones in the Central Western Kunlun Mountains, China

Abstract The Saidikulam nephrite deposit, which is famous for its high-quality white no matter in history and nowadays, located the eastern part of Western Kunlun Orogen, northwestern margin Tibetan Plateau, Yutian County, Xinjiang, China. Field investigations petrographic observations revealed presence five mineral assemblage zones from granodiorite to dolomitic marble deposit: slightly epidote-altered ? diopsidite calcite tremolitite calcite-bearing marble. However, little known about relationships among these or formation age deposit. consists plagioclase, orthoclase, quartz, biotite, epidote, with accessory apatite, zircon, allanite. They exhibit negative Eu anomalies (0.69–0.72), declined light rare earth element (LREE) flat heavy (HREE) patterns. are also strongly enriched Rb, Zr, U, Sm depleted Hf, Ti, P, Nb. close intrusions a relatively high-temperature metasomatic rock composed Fe-rich diopside actinolite, while adjacent low-temperature prismatic tremolite calcite. main component tremolite, minor chlorite, calcite, graphite, nephrites have low ?REE contents (4.38–18.53 ppm), LREE HREE All analyzed exhibits pronounced (?Eu = 0.20–0.82), they Ti Ba HFSEs. SHRIMP U–Pb dating zircons yielded Concordia 453.8 ± 3.7 Ma, interpreted as upper limit age. epidotized syenite deposit 489.2 4.2 Ma. These two ages indicate that experienced at least thermal events. approximate deposits along giant Kunlun-Altyn Tagh belt closure Proto-Tethys may been predominant driving force whole deposits. multistage metasomatism Fe absorption had positive impact on nephrite.