Mineral Deposit Model Of The Duolong Deposit Cluster In Gaize County, Tibet And Its Application

Duolong gold-rich porphyry copper deposit cluster is located on the north of theBangonghu-Nujiang suture zone, at the south margin of Qiangtang Block and in GaizeCounty, North Tibet. It is a super-large copper-gold deposit and has very goodperspective, including8ore districts: Dibaonamugang, Nadun, Bolong, Duobuza,Naruo, Tiegelong, Sena, Gaerqin. There are more than7Mt Cu with a grade of0.46%-1.13%and more than168.8t gold with a grade of0.15-0.26g/t controlled in Duobuzaand Bolong. By analyzing the ore deposit geology, geochronology, Magma evolution,material source, fluid inclusions and prospecting techniques in different deposits ofthe cluster, we propose the mineral deposit model of the Duolong deposit cluster andpoint out the potential ore-prospecting area. The main achievements in thisdissertation are as follows:1. Duolong deposit cluster is gold-rich copper deposit related to the earlycretaceous porphyry intrusion into the Jurassic and cretaceous. Ferritization andmalachitization are developed on the surface in deposit cluster. The metallogeneticporphyry develops strongly hydrothermal alteration. The porphyry is almost whollymineralized. The main ore mineral includes pyrite, chalcopyrite, sphalerite, magnetiteand a small amount of molybdenite etc., gangue mineral includes quartz, feldspar,sericite, anhydrite and carbonate minerals. Dravite is found in Bolong drill samples, itmay provide important evidence of material sources in salt lake, north Tibet.2. The ore-forming process of Duolong deposit cluster occur in110Ma~120Ma.According to the age characteristics, deposits in cluster can be divided into threeperiod: Duobuza, Bolong, Naruo, Tiegelong and Gaerqin are the earliest (~120Ma);Nadun deposit takes the second place (~115Ma); Dibaonamugang is the latest(~111Ma). From northeast to southwest, the formation time of deposits becomeyounger. Duolong belongs to the110~120Ma large-scale metallogenic phase in Ban-Nu metallogenic belt.3. Petrogeochemistry characteristics indicate that the ore-bearing porphyry in theDuolong copper cluster may be from mantle and influenced by ocean sediments and lower crust material. The ore-bearing porphyry has the characteristics of island arcmagma. Cu, S should be mantle-derived.4. The thermometry of fluid inclusion in Duolong cluster reveals that themetallogenic temperature of Duobuza and Bolong arrange300℃to450℃, the fluid ismainly derived from the magma; the metallogenic temperature of Dibaonamugangand Nadun is240~280℃and185℃～395℃respectively, the fluid is mainly derivedfrom the magma and influenced by meteoric water.5. By summarizing the geology, geophysical exploration, chemical explorationand remote sensing in Duobuza and Bolong, we propose an exploration model a ndpoint out the Dibaonamugang and Nadun should be a good potential ore-prospectingarea.