四川省拉拉铜矿田矿床成因模型

四川省会理县拉拉铜矿田处于川滇被动大陆边缘裂谷系的构造环境，成矿作用受会理-东川裂陷槽构造-岩浆演化控制。矿体产于古元古界河口群富钠质的细碧-角斑岩系中。矿石中金属硫化物的δ34S值集中分布在-1‰~4‰之间，均接近0，具塔式分布特征，表明硫主要来自火山喷发作用。矿床与火山喷流沉积型矿床的流体类型相似，其包裹体基本为早期石英硫化物中的Ⅰ型包裹体及后期方解石、石英硫化物中的Ⅱ和Ⅲ型包裹体，Ⅰ型包裹体反映为火山喷发沉积期的主成矿阶段；而Ⅱ型和部分Ⅲ型包裹体反映了晚期流体混溶现象，显示矿床经历了后期改造。根据同位素测年数据，将矿床的成矿过程大致分为火山喷流作用（1600~1800 Ma）、变质变形作用（1000~1100 Ma）和热液叠加改造作用（770~900 Ma）3个阶段。初步认为拉拉铜矿田矿床成因类型属海相火山岩型铜矿床，但河口群不同的火山喷发旋回具有不同的矿化样式。

A discussion on the genetic model of the copper deposit in Lala copper orefied,Sichuan Province

The tectonic environment of the Lala copper orefield is located in the Sichuan-Yunnan passive continental margin rift system of Huili County, Sichuan Province, and its mineralization is controlled by the tectonic-magmatic evolution of the Huili-Dongchuan rift trough.The orebody is located in the Na-rich spilite-keratophyre series of the Paleoproterozoic Hekou Group.The values of the δ34S of metal sulfide in the ore are distributed in the range of -1‰~4‰, and are close to zero, which have characteristics of tower distribution, indicating that sulfur mainly came from volcanic eruption.The fluid type of the deposit is similar to that of the volcanic effusive sedimentary deposit, the inclusions are basically Ⅰ-type inclusions in early quartz sulfide and Ⅱ-type and Ⅲ-type inclusions in late calcite quartz sulfide; I-type inclusions reflect the main metallogenic stage of volcanic eruptive-sedimentary period, while Ⅱ-type and Partial Ⅲ-type inclusions reflect terminal fluid miscibility, which indicates that the deposit has undergone late reformation.According to isotopic dating data, the metallogenic process of the deposit can be roughly divided into three stages:volcanic spouting(1600~1800 Ma), metamorphism and deformation(1000~1100 Ma), and hydrothermal superposition modification(770~900 Ma).It is preliminarily considered that the genetic type of deposits about the Lala copper orefield belongs to marine volcanic rock type copper deposit, but different volcanic eruption cycles of Estuary Group have different mineralization patterns.