昌达沟斑岩型铜矿床地质特征及成因探讨

发布时间：2018-02-08 16:25

本文关键词： 斑岩地球化学昌达沟　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：昌达沟斑岩铜矿床位于义敦岛弧主弧带北段,处于德格—义敦—香格里拉斑岩铜矿成矿带北段。研究区内出露地层为一套巨厚的晚三叠世碎屑岩,由此组成一个北西西-北北西向弧形复式向斜。在昌达沟矿区及外围的140km2范围内,共有中酸性小型侵入体及其超浅成岩枝126个,主要由花岗岩、石英闪长岩、次石英安山岩、流纹英安岩等岩石组成,在小范围内呈群,大区域内呈带分布,具有一定的层位。昌达沟铜矿主要由两个含铜花岗闪长(斑)岩体组成。矿石以细脉浸染状为主,浸染状和脉状次之,块状矿石少见。金属矿物以黄铁矿、磁黄铁矿、含铜黄铁矿为主,黄铜矿少见。各矿体平均铜品位变化与0.31~1.58%之间,多数为0.5%左右,属低品位贫矿;金一般0.1×10-6,少量0.1~0.4(×10-6),个别为26×10-6;矿床规模为小型。矿体的围岩蚀变主要出现在岩体本身及接触带,主要有钾化、硅化、绢云母化和绿泥石化,分带不明显。该矿床属于斑岩型铜矿的一个亚类,主成矿阶段为热液期。本文主要研究内容包括:区域地质背景、区域岩浆岩特征、矿床地质特征、年代学、矿床地球化学特征、成因探讨等。通过以上研究,取得以下成果和认识:(1)昌达沟矿区花岗闪长斑岩主要属高钾钙碱性系列;岩石铝质含量较高,为典型的过铝质岩石;含矿斑岩钾质含量很高,为典型的钾质岩石系列,这与义敦岛弧南段的大型斑岩体的性质相似。(2)昌达沟矿区含矿花岗闪长斑岩的地球化学特征暗示其源区物质来源比较浅,斑岩可能主要由地壳物质重熔形成,且可能有少量洋壳物质的混染。(3)常量元素特征表明其可能形成于弧环境(岛弧或大陆弧)或大陆碰撞环境,但与大陆弧环境最为密切;同时与造山作用密切相关。微量元素特征表明含矿斑岩可能形成于高成熟度的火山弧或陆弧环境。综合分析认为,昌达沟铜矿区含矿花岗闪长斑岩最有可能形成于弧构造环境,并且其可能与大陆弧环境更为密切。昌达沟斑岩铜矿形成的构造环境与义敦岛弧带南段和中段的普郎、雪鸡坪、春都等矿床基本一致。(4)通过锆石测年显示昌达沟斑岩体的成岩年龄为208~216Ma,属于印支期,并非前人所说的燕山期,与义敦岛弧南段的普朗、雪鸡坪等斑岩体的成岩年代一致。根据义敦岛弧的活动时段250~208Ma,岩浆活动的高峰期在215Ma。(5)长期以来,前人认为义敦岛弧北段昌达沟一带的斑岩体为燕山期,与义敦岛弧南段岩浆活动和构造环境存在较大差异,不具备南段形成大型斑岩条件的地质背景。本次研究发现,北段昌达沟地区的斑岩体为印支期,岩体的地质地球化学特征与形成时代与南段含矿斑岩体具有很大的相似性,同时也存在与南段斑岩体成矿相似的地质背景,因此义敦岛弧北段具有较大规模的斑岩型铜矿的成矿潜力。目前未取得较大突破与工作程度较低有关。
[Abstract]:The Changdagou porphyry copper deposit is located in the northern segment of the Yidun island arc main arc belt and in the northern segment of the Dege-Yidu-Shangri-La porphyry copper metallogenic belt. The outcrop layer in the study area is a set of extremely thick late Triassic clastic rocks. In the range of 140 km ~ 2 of Changdagou mining area and its periphery, there are 126 intermediate-acid small intrusions and their ultrashallow diagenetic branches, mainly composed of granite, quartz diorite and subquartz andesite. The rocks, such as fluid-striped dolomite, are grouped in a small area and distributed in a large area with a certain horizon. The Changdagou copper deposit is mainly composed of two copper-bearing granodiorite (porphyry) rocks. The ore is mainly vein-impregnated, and the ore is mainly composed of two copper-bearing granodiorite (porphyry). Secondly, disseminated and veined ore are rare. The metallic minerals are pyrite, pyrrhotite, copper pyrite, and chalcopyrite. The average copper grade of each ore body varies from 0.31 to 1.58%, mostly about 0.5%, belonging to low grade poor ore. Gold is generally 0.1 脳 10 ~ (-6), a small amount is 0.1 ~ (-6) (脳 10 ~ (-6)), each is 26 脳 10 ~ (-6). The scale of the deposit is small. The alteration of the surrounding rock of the orebody mainly occurs in the rock body itself and in the contact zone, and mainly includes potassium, silicification, sericite and green-mud petrifaction. The ore deposit belongs to a subclass of porphyry copper deposit and the main metallogenic stage is hydrothermal epoch. The main contents of this paper include: regional geological background, regional magmatic rock characteristics, deposit geological characteristics, geochronology, etc. Based on the above study, the authors obtained the following results and realized that the granodiorite in Changdagou mining area is mainly of the high-potassium calc-alkaline series, and the aluminous content of the rocks is relatively high, which is typical of peraluminous rocks. The ore-bearing porphyry is a typical series of potash rocks, which is similar to the large porphyry body in the southern segment of Yidun Island Arc. The geochemical characteristics of the ore-bearing granodiorite in Changdagou area suggest that the source material source is relatively shallow. Porphyry may mainly be formed by crustal material remelting, and there may be a small amount of oceanic crust material mixed dye. 3) the characteristics of constant elements indicate that porphyry may be formed in arc environment (island arc or continental arc) or continental collision environment, but it is most closely related to continental arc environment. The trace element characteristics indicate that the ore-bearing porphyry may be formed in the high-maturity volcanic arc or continental arc environment. The comprehensive analysis shows that the ore-bearing granodiorite in Changdagou copper deposit is most likely formed in the arc tectonic environment. The tectonic environment of Changdagou porphyry copper deposit and the Pulang and Xuejiiping of the southern and middle segments of the Yidun Island Arc Belt are also likely to be more closely related to the continental arc environment. The zircon dating of the Changdagou porphyry shows that the diagenetic age of the Changdagou porphyry body is 208- 216Ma.It belongs to the Indosinian epoch and is not the Yanshanian period, which is referred to as the Yanshanian epoch, and the Plang in the southern segment of Yidun Island Arc. The diagenetic age of the porphyry bodies such as Xuejiiping is the same. According to the active period of the Yidun Island Arc at 250 ~ 208 Ma, the peak of magmatic activity is at 215 Ma.) for a long time, the porphyry in Changdagou area of the northern segment of the Yidun Island Arc is considered to be Yanshanian period. The magmatic activity and tectonic environment in the southern segment of Yidun Island Arc are quite different, and there is no geological background for forming large porphyry conditions in the southern segment. This study found that the porphyry in the Changdagou area of the northern segment was an Indosinian period. The geological and geochemical characteristics of the rock mass are similar to the ore-bearing porphyry in the south segment, and the geological background is similar to that of the porphyry in the south segment. Therefore, the northern segment of Yidun Island Arc has the metallogenic potential of large scale porphyry copper deposits.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.41

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