Structural setting of the Narusongduo Pb-Zn ore deposit in the Gangdese belt, central Tibet

• DOI: 10.1016/j.oregeorev.2022.104748
• Publication Date: 2022-02-05T15:24:36Z
• Authors: Qin Qin; Linglin Zhong; Kanghui Zhong; Zhiyuan He; Zhao Yan; Stijn Dewaele; Jie Peng; Hongjie Zhang; Johan De Grave; Wenbo Su; Haozhen Huang; Xingjie He; Huiwen Zhou; Guoqiang Yan; Hairui Yang; Yilong Liu; Shucheng Shan; Gang Yang; Jiaqiang Li; Xiaohong Huang
• Keywords: Gangdese retroarc; FLUID INCLUSIONS; MO DEPOSIT; Lhasa terrane; LHASA TERRANE; VOLCANIC-ROCKS; FAULT-VALVE BEHAVIOR; Geology; U-PB; 01 natural sciences; EVOLUTION; Linzizong volcanic succession; Luobadui-Milashan fault; PORPHYRY CU-AU; Geochemistry and Petrology; Structural controls; Earth and Environmental Sciences; Narusongduo ore deposit; RE-OS GEOCHRONOLOGY; Economic Geology; MAGMATIC BELT; 0105 earth and related environmental sciences

The Narusongduo Pb-Zn deposit is located at the northern boundary of the Luobadui-Milashan fault zone (LMF) in central Tibet and is spatially associated with the Linzizong volcanic succession (LVS). Our study indicates that the regional structural setting was formed by two-stage tectonic events. The first stage, spanning from the late Mesozoic to early Paleocene, is characterized by significant N-S crustal shortening associated with the Cordilleran-type orogeny along the Gangdese arc. The region's Paleozoic-Mesozoic metasedimentary rocks were penetratively strained. Locally deformation was largely partitioned along the LMF. During the second stage (ca. 66-55 Ma), the area was affected by extensive multi-stage Linzizong volcanism, including caldera formation, as well as a coaxial N-S propagative deformation with a distinctive lower shortening rate. We recognized two types of mineralization, both were formed during the second stage. The first type of mineralization (orebody III) is governed by fractures within the extensively deformed Paleozoic carbonate rocks at the LMF's footwall. The overlying LVS, however, includes discrete but numerous mineralized sections. The terminal splays of the ore shoots typify the products of hydraulic fracturing. We propose that the propagative compressive deformation drained fluid reservoirs at depth to higher levels via the "Fault valve" effect. Episodic fluid influxes and mineral deposition formed the time-integrated mineralization. The second type of mineralization (orebody I) is hosted in the LVS in a number of breccia pipes and dykes that were controlled by the structural weaknesses generated by the intersection of the radial and ring fractures. Mineralization occurs as veinlets in the matrix and clasts inside the breccias, which are characterized by multi-stage brittle cracking, fluid injection and mineral precipitation. It is interpreted that the multi-stage magmatism (ca. 66-55 Ma) triggered repeated hydrothermal activities and incremental mineralization within the ore-bearing breccia bodies.