粤东新寮岽铜多金属矿床绿泥石特征及其地质意义

Characteristics of chlorite from the Xinliaodong Cu polymetallic deposit in eastern Guangdong Province and their geological significance

新寮岽铜多金属矿是近年来在粤东地区新发现的一个铜矿床,在该矿区绿泥石化十分强烈,并与铜矿化关系密切.按照矿物共生组合关系,矿区绿泥石可分为与硫化物共（伴）生及未与硫化物共（伴）生呈单独产出两类,两类绿泥石主要呈叶片状、纤维状、蠕虫集合体状等形态产出.本文在岩矿鉴定的基础上,以矿区绿泥石为研究对象,利用电子探针技术,对其微区化学成分进行了研究.结果表明：随着孔深的增加,与矿化有关绿泥石的Si和Mg元素含量逐渐升高,Al、Fe、Mn元素含量逐渐降低,而与矿化无关的绿泥石成分变化规律不明显.两类绿泥石主要为富铁种属的蠕绿泥石、铁镁绿泥石;绿泥石为泥质岩或者铁镁质岩受热液交代蚀变的产物,绿泥石结构的离子置换主要体现为Fe对Mg的置换,反映其可能形成于富铁及相对酸性环境;由绿泥石地质温度计估算得出两类绿泥石形成温度为166.32～245.62℃,平均为219.15℃,且与硫化物共（伴）生的绿泥石的形成温度相对较高,但两者均属中-低温范围.绿泥石的形成机制主要表现为溶蚀-结晶和溶蚀-迁移-沉淀结晶2种.

The Xinliaodong Cu polymetallic deposit is a newly-discovered copper ore deposit in eastern Guangdong Province.Chlorite is one of the main hydrothermal alteration minerals genetically related to copper mineralization in this ore district.According to the mineral intergrowth association,the chlorites of Xinliaodong Cu polymetallic ore district can be classified into two types：the chlorite which coexists with sulfide and the chlorite which occurs individually.Both chlorites exhibit foliate,fibrous or vermicular aggregation forms.By means of microscopic and electron microprobe analysis,the authors investigated chemical composition and texture of the chlorite and concluded that chlorites in the Xinliaodong Cu polymetallic deposit have the following characteristics：① with the increasing altitude,the Si and Mg components of the chlorite related to mineralization increase gradually,the Al,Fe and Mn components gradually decrease,but the regularity is not apparent for the chlorite which had nothing to do with mineralization; ② the two types of chlorite are mainly Fe-rich chlorites composed of prochlorite and brunsvigite; ③ they were formed by hydrothermal alteration of pelitic or mafic rocks,and the phenomenon that Fe-Mg substitution dominates the octahedral substitution suggests that their formation had to do with the iron-rich and relatively acid environment; ④ according to the chlorite geothermometer,the two types of chlorites were formed at temperatures of 166.32～245.62℃ （averagely 219.15℃）and the chlorite coexistent with sulfide had a relatively higher formation temperatures,but both of them were in the range of lowmoderate temperature; ⑤ the main formation mechanisms of the two types of chlorites were dissolution-crystal-lization and dissolution-migration-crystallization.