| Laojunshan ore-concentration area,located at the contact zone between Indosinian Block and South China Block,is a major part of the W-Sn polymetallic metallogenic belt in southeast Yunnan province.In this paper,three typical deposits in the Laojunshan ore-concentration area are taken as research objects.Through the analysis of regional tectonic deformation,ore-controlling structure,the geological characteristics of the deposits,and their diagenetic ore-forming tectonic setting,the temporal-spatial distribution of ore-controlling structural factors and their effects have been clarified.In addition,the evolution and metallogenic regularity of the three typical deposits are discussed to finally establish a comprehensive ore-controlling–prospecting mode for this area that ore concentrated.The main insights of this research are as follows:1.According to the geological characteristics of the Dulong Sn-Zn-In deposit,the Nanwenhe W deposit and the Saxi Emerald deposit in the Laojunshan ore-concentration area,the ore-controlling structure characteristics and their effects on the formation of these deposits can be clarified.By the geochronological dating and the geochemical analysis,the genesis,the metallogenic age,the metallogenic tectonic setting,and the metallogenic regularity of the three typical deposit are all probed.2.Two types of mineralization responding to different ore-controlling structures have been identified.The ductile shear plane dominated by thrust nappe structure at the Middle Jurassic is the ore-forming space of the layered skarn type W deposit.The decollement fault and brittle shear fissure formed by extensional structures at the late Yanshanian are the ore-forming space of the W and Emerald veined ore bodies in the Nanwen River–Saxi area.3.The geological characteristics and metallogenic factors of typical deposits in the ore concentration area have been analyzed and summarized.It turns out that it is the structure that primarily controlled the metallogenic regularity.This ore-concentration area is dominated by the thrust nappe structure in the Middle Jurassic and extensional structures at the late Yanshanian,which collectively formed an “extrusion nappe–extension decollement–regional strike-slip” structure evolution sequence controlling the ore bodies.Types of these structures are the key factors dominating the mineralization,including the form of structural deformation(mineralization space),the distribution of ore-forming stratigraphic(distribution of ore-bodies),the forming of the metallogenic barrier layer(mineralization geochemical barrier),and the transport space of magmatic hydrothermal(morphology of ore body),all controlled by the structures mentioned above.4.A new comprehensive ore-controlling–prospecting model of “four ore-forming stages–three ore-hosting layers–two types of ore-controlling space–one ore-forming related intrusive body” are established,and the metallogenic regularity in the ore-concentrating area are also clarified.Finally,the promising areas for further prospecting are then provided. |
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