Structural Ore-controlling Model And Its Exploration Direction In The Lehong And Xiaohe Zn-Pb Deposit In Northeastern Yunnan

Lehong zinc-lead deposit is a new-found large scale Pb Zn deposit in recent years in the Sichuan-Yunnan-Guizhou zinc-lead poly-metallic mineralization domain,and the output of the ore body is strictly controlled by structure.This article uses the geomechanics theory and method of ore fields,through thescale structural section precise measuring and structural ore-controlling rele to analysis geometry,kinematics,mechanics,tectonite characteristic of typical metallogenetic tectonics and repeated tetonic movements,and then to identify the mechanical properties and divide techonic system.On these basis to establish mineralizing tectonic system,summary tectonic ore-controlling regularity and to analyse the mechanism of the structural controlling of metallogenesis,and to establish tectonic ore-controlling model.1.Tectonics are well developed in Lehong and Xiaohe Zn-Pb deposit,which have the charateristics of multi period tectonic activity.The nearly NE trending Qiaojia-Lianfeng fault and Lemachang fault as high level control structures within the ore field,controlling the location and distribution of ore field.The Lehong fault control the location and distribution of diposits.The joints as a low level structures and interlayer fault zones control the distribution of ore-bodies.These reflect tectonic control relationship in order,which constitutes a tapical folds-faults-joints roch and ore-forming tectonics system.2.Since the Caledonian,the main constructional compressive stress in the Lehong and Xiaohe ore field has experienced the transition from near EW trending?NE 45°-50° trending?NW 50°-60° trending?NE 45°-50° trending ?near EW trending ?near SN trending,it is suggested that this deposit has 4 kinds of structural associations,which represent the six tectonic system,,and correspond to Caledonian,Hercynian,Indosinian-early,Indosinian mid and Late to Yanshanian-early,Mid Late Yanshanian period and himalayan epoch.It formed the metallogenic framework in the Lehong and Xiaohe ore field that NW trending tectonic belt in the Indosinian mid and Late to Yanshanian-early.3.The output of the ore body is strictly controlled by structure,according to relationship of spatial location between different ore-bodies and structures,the Lehong and Xiaohe Zn-Pb dopisit can be divided into three mineralization pattern:1)near the Lehong fault ore-bodies are massive and lenticularity.2)The ore-bodies are mesh-vein and nodular farther from the Lehong fault.3)Away from the fault zone ore-bodies are vein and disseminated,it is hosted at the interlayer fault zones.4.It is concluded that the combination of Lehong fault and the altered dolomite of Sinian Dengying Formation is the metallogenic geological body of the Lehong and Xiaohe Zn-Pb deposit,and this deposit can be divided into 3 types of ore-forming structural plane:1)Lithologic interface,include Si-Ca interface.2)Tectonic metallogenic structural plane.3)Physical and chemical ore-forming structural plane,include Eh-pH interface.5.Though the analysis in the regularity of structural ore controlling help us build tectonic controlled model of Lehong lead-zinc and sum up four prospecting criteria.The contact region of the Lehong fault and dolomite of Sinian Dengying Formation and the contact interface of dolomite of Sinian Dengying Formation and sandstone of Cambrian Qiongzhusi Formation are favorable areas of prospecting in the fulture.We provide six prospecting foreground zones.