Study On Nedong County Nuri Cu Polymetallic Deposit Ore-controlling Structure In Tibet

Nuri polymetallic deposit tectonics located in Chayu magmatic arc which under the ladakh-southern Gangdese magmatic arc. metallogenic belt belongs to Nimu-Sangri sub-belt. After mining area do large scale charting and comprehensive research in laboratory. find out the emergence stratum were Bima group third、fourth、fifth lithologic section., Nu-Ri polymetallic ore deposit located in sub-fault structure in northward branch of anticline zone. The deposits go through multi-stages and multi-times magmatism, which has superposition metallogenic features.This area is influenced by tectonic movement at late Yanshanian period. On one hand, the district first developed fragmentation effect of the Longitudinal bending buckling and rock shallow. On the other hand, the district formed hug e ductile(shear zone and fracture), which prepared good migration pathways for intrusion movement of acidic magma at the same or late period. With emplac ement of diorite rock mass at Late Cretaceous, skarnization in the mining area. Impact by early and middle action of collisional orogeny and extension slip in Himalayan, a series of east-west trending complex fold and a large scale of N WW-SEE Thrust fault and W-N and NWW-SEE tenso-shear secondary fault. Alo ng with pathways formed at the previous and current period, the medium-acidic magma at the same and late period, proceed invasion and migration, and occure d mineralization. Finally, mineral deposit mineralized in place at the Middle and Late Paleogene period. combined with regional skarn deposits age of68-40Ma, it indicated that the main mineralization stage of the deposits was as early as the mid-Himalayan peroid.Tectonic zone of this area from north to south can be divided into the following p arts:Dazi-Pulonggang complex uplifted fold belt, complex downwarped fold belt, Ch angguo complex Anticline fold belt, the Yarlung Zangbo River complex Fault belt an d so on. Changguo complex Anticline fold belt which is consist ofChangguo anticlinor ium, Jiedang reverse fault and Sangbo fault, are mainly in the south of Gubula thrus t faults. In this belt, main stratum are the Cretaceous period lowerMamu (J3K1m) an d Bima Fm(K1b), Changguo anticlinorium only can be found in the south wing and t he Yarlung Zangbo River fault zone in the south, Through this research,Nuri Cu poly metallic deposit is located in the north wing of Changguocomplex Anticline fold belt, t he structure of this mining area is complex anticline. In planar graph, it appear like s "M", its axial plane near east and west, pitching to west, consisting of the fourth litho logic section (K1b4) and the superstructure third lithologic section. The development o f the joint system in this area and the transformation of the upfold are happen at the sa me time, as a result, joint fissure and interformational fracture zone appeared. Due to th e uplift deformation, the previous joint fissure are becoming sharp, and also providin g a perfect space for the formation of ore reservoir.Nuri Cu-polymetallic deposit is a typical skarn deposit,study can indicated that mining area skarnization have a closely connection with fouth lithologic section in Bima group, a set of clasolite and carbonatite interbedding in fouth lithologic section (Kib4) in Bima group, lithological association were sandstone and limestone. The boundary of the Minerogenetic magma hydrothermal solution is indentation,pass the hosting strata structure through it、filling-metasomatic、mineralization, especially in the carbonatite.it has a little connection with the upper third lithologic section thick-layer massive limestone. Mining area skarnization and mineralization controlled by tectonic is obviously, its ore-controlling structure is complex fold, ore-bearing structures a set of clasolite and carbonatite interbedding in fouth lithologic section (Kib4).the deposit body presents vein、lens、stratoid、and the host rock is skarn.Carbonatite in fouth lithologic section (Kib4) in Bima group make a good preparation for ore bodies are hosted by sedimentary rock,and clasolite act as cap and baseplate for deposit forming, ore solution gathering in interlayer joint fracture in fouth lithologic section of Bima group (K1b4),at last, forming deposit.To sum up, it is the study on Nuri Cu polymetal deposit ore-controlling structure,not only make a good direction for further prospecting, but also can help neighbour geology work in some level.