大渡河金成矿带基性岩脉特征对比

发布时间：2018-08-08 21:47

【摘要】：大渡河金成矿带基性岩脉分布广泛,在大渡河金成矿带内各金矿床都有出现,且空间走向也存在一定的差异。近年来,很多学者、专家对该处基性岩脉与金成矿的关系提出了很多观点,有人认为这些基性岩脉与大渡河金成矿带上金的成矿有密切的关系,也有人认为二者之间并没有直接的关系。前者认为大渡河金成矿带各金矿床都有基性岩脉出现且多与含矿石英脉呈侵入接触关系,后者认为前者并没有直接的证据说明该区基性岩脉的形成期次与该区金矿形成的构造期次相同,对其在成因上的关系并没有系统的研究。针对该问题,笔者在导师的指导下,通过对大渡河流域基性岩脉在不同时代、不同基性岩带两方面进行详细研究对比,得出以下认识:1.大渡河金成矿带内基性岩脉成岩年代主要分为三个时期:印支期(212Ma~224Ma)、加里东期(425Ma~435Ma)、晋宁期(731Ma~754Ma),其中晋宁期基性岩脉主要分布于基底杂岩中,加里东期、印支期基性岩脉分布较广,在基底杂岩和沉积盖层中都有出露。大渡河金成矿带内含矿石英的ESR测年表明其形成于喜山期(陈颖,2015)。综合大渡河金成矿带内基性岩脉与含矿石英的岩石学特征及年代学分析,目前看来,大渡河金成矿带内基性岩的形成时代要早于其中金矿。2.大渡河金成矿带内3个时期的基性岩脉形成于火山岛弧环境、碱性洋中脊环境和板内拉张环境;据所测得的研究区基性岩脉样品的微量元素数据显示,Zr/Y比值、Zr/Nb比值均小于18,因此该区基性岩脉的成岩物质来源于富集地幔。3.从地质特征上可以看出研究区基性岩脉都发生了较强的蚀变作用,都具残余变晶结构的特点,同时都受到了后期硅质热液流体的侵蚀作用。
[Abstract]:The basic rock veins in the Daduhe gold metallogenic belt are widely distributed, and all the gold deposits appear in the Daduhe gold metallogenic belt, and there are some differences in the spatial strike. In recent years, many scholars and experts have put forward a lot of views on the relationship between the basic vein and gold mineralization. Some people think that these basic rock veins are closely related to the mineralization of gold in the Dadu River gold metallogenic belt. Others argue that there is no direct relationship between the two. The former holds that the gold deposits in the Daduhe gold metallogenic belt have basic rock veins and have intrusive contact with ore-bearing veins. The latter holds that the former has no direct evidence to show that the formation stage of the basic vein in this area is the same as that of the gold deposit in this area, and there is no systematic study on the relationship between the origin of the basic vein and the tectonic stage of the gold deposit in this area. Aiming at this problem, the author, under the guidance of his tutor, makes a detailed study and comparison of the basic rock veins of the Dadu River Basin in different times and different basic rock belts, and obtains the following understanding: 1. The diagenetic age of the basic vein in the Daduhe gold metallogenic belt is divided into three periods: Indosinian (212Ma~224Ma), Caledonian (425Ma~435Ma), Jinning (731Ma~754Ma), in which the Jinning basic-vein is mainly distributed in the basement complex, and the Caledonian and Indosinian basic-vein are widely distributed. Both the basement complex and the sedimentary caprock are exposed. The ESR dating of ore-bearing elements in the Daduhe gold metallogenic belt indicates that it was formed in the Xishan period (Chen Ying 2015). Based on the petrological characteristics and geochronological analysis of the basic veins and ore-bearing rocks in the Daduhe gold metallogenic belt, it appears that the age of formation of the basic rocks in the Daduhe gold metallogenic belt is earlier than that of the gold ore. The basic veins of the three periods in the Daduhe gold metallogenic belt were formed in the volcanic island arc environment, the alkaline mid-oceanic ridge environment and the intraplate extensional environment. The trace element data of the basic vein samples in the study area show that the ratio of Zr / Y and Zr / NB are all less than 18, so the diagenetic material of the basic vein in this area is derived from the enriched mantle. From the geological characteristics, it can be seen that all the basic veins in the study area have undergone strong alteration, all have the characteristics of residual amorphous structure and have been eroded by siliceous hydrothermal fluids in the late stage of the study area.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.51

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