滇东北富锗银铅锌多金属矿集区矿床模型

Mineralization Model of Rich Ge-Ag-Bearing Zn-Pb Polymetallic Deposit Concentrated District in Northeastern Yunnan, China

滇东北富锗银铅锌多金属矿集区是扬子地块西南缘之川-滇-黔铅锌多金属成矿域的重要组成部分。矿床矿石品位特高、共(伴)生锗和银等组分多、矿体延深大、矿床规模大、经济价值巨大,该类矿床典型的地质特征反映了矿床成矿环境的特殊性,有别于国内外已知类型铅锌矿床(密西西比河谷型(MVT)、火山喷流沉积块状硫化物型(VHMS)、热水沉积型(SEDEX)等)的特性,提出了该类矿床是铅锌矿床的新类型——会泽型(HZT)铅锌矿床,其形成与海西晚期伸展环境与印支期造山挤压环境的构造体制转换有关,并建立了"构造-流体‘贯入’成矿"的矿床模型。矿床的形成过程大致经历了3个阶段:构造推覆—大规模流体运移;流体"贯入"—气液分异;流体卸载—重力分异成矿。该模型诠释了滇东北矿集区富锗银铅锌多金属铅锌矿床的成矿机理,无疑对川-滇-黔铅锌多金属成矿域的矿床研究与深部、外围的隐伏矿定位预测、勘查评价具有重要意义。

The deposit concentrated district of germanium-silver-bearing lead-zinc polymetallic ore deposits in northeastern Yunnan is an important component of the Sichuan-Yunnan-Guizhou lead-zinc polymetallic mineralization domain in the southwestern margin of the Yangtze block. The deposits are characterized by very high grade of the ore, more associated minerals such as germanium and silver, deep extension of ore bodies, large scales of the ore deposits, and great economic value. The deposits of this kind reflect a typical ore-forming environment, which is different from known lead-zinc deposit types discovered in both China and abroad, such as Mississippi Valley Type （MVT）, Volcanic Hosted Massive Sulfide Type （VHMS）, and Hydrothermal Sedimentation Type （SEDEX）. Therefore, this study proposed that this kind of deposits is representative of a new Pb-Zn deposit type-Huize type （HZT）. The formation of these deposits was related to tectonic regime transformation from late Hercynian tectonic extension to Indosinian orogenic extrusion, and this was responsible for the establishment of a new mineralization model - ＂structural fluid penetration mineralization＂ model. The formation of such ore deposits has gone through three phases： A） trusting structure and large-scale fluid migration; B） fluid ＂penetration＂ and gas differentiated from liquid; C） fluid unloading and mineralization by gravity differentiation. This model can be used to interpret the mineralizing mechanism of the lead-zinc deposits occurring in the ore deposit concentration district of northeastern Yunnan. This is undoubtedly of great importance in studying Sichuan-Yunnan-Guizhou lead-zinc polymetallic metallogenic field, and in prediction, exploration and evaluation of concealed ore localization in the deep parts and external district of the type deposits.