河南老李湾岩体地质特征及成矿模式

Geological characteristics and metallogenic model of Laoliwan rock mass in Henan

老李湾矿床是华熊台隆崤山隆断区东部边缘一大型银多金属矿床,通过对区域地质背景、矿床地质特征、岩体形态、地球化学、岩体年龄的研究,表明岩体侵入受NW向F1断裂的控制,且至少经历三次侵入过程;老李湾岩体是壳源岩浆与幔源岩浆混合作用的产物,年龄为(149±11)Ma,属燕山期中国东部构造体制大转换的产物。期间由于扬子陆块和秦岭造山带向北的陆内俯冲,华北陆块南缘便持续不断隆起抬升,并在陆内造山作用下,形成一系列自北向南或自南向北的大规模逆冲推覆和岩浆侵入活动。初步建立了成矿模式:挤压构造环境下,花岗质岩浆沿断裂侵位,随岩浆而来的含矿流体在岩体就位过程中随着温度、压力等条件的改变以及大气水的加入而发生矿化作用,岩体中心部位形成斑岩型矿体,周边形成脉状矿体。

Laoliwan deposit is a large silver polymetallic deposit in the eastern margin of Xiaoshan rising faulted zone of Huaxiong platform. Based on the research of regional and geological background, geological characteristics of deposit,rock mass shape and age, geochemistry, it is shown that the intrusion of rock mass is controlled by fault F： in NW direction with at least three processes. Laoliwan rock mass is the product of mixture function of crust magma and mantle magma. Age of the rock mass is （149±11） Ma, which is belonged to the product of tectonic system transformation of eastern China in Yanshan period. During the period , southern margin of the North China block is continued to rise and to uplift because of the northward in-tra-continental subduction of the Yangtze block and Qinling orogenic belt. There are formed for a series of large-scale thrusting and magmatic intrusion from north to south or from south to north. This paper has established the preliminary metallogenic model. The granitic magma is emplaced along the faults in compressive tectonic environment, and the mineralization takes place in the ore fluid derived from magma because of the changing of temperature and pressure condition and the addition of atmospheric water in the emplacement process of rock mass. The ore body of porphyry type is formed in the central part of rock mass and orebody of vein is formed in the peripheral.