本文關鍵詞： 斑巖 地球化學 昌達溝　出處：《成都理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：昌達溝斑巖銅礦床位于義敦島弧主弧帶北段,處于德格—義敦—香格里拉斑巖銅礦成礦帶北段。研究區(qū)內(nèi)出露地層為一套巨厚的晚三疊世碎屑巖,由此組成一個北西西-北北西向弧形復式向斜。在昌達溝礦區(qū)及外圍的140km2范圍內(nèi),共有中酸性小型侵入體及其超淺成巖枝126個,主要由花崗巖、石英閃長巖、次石英安山巖、流紋英安巖等巖石組成,在小范圍內(nèi)呈群,大區(qū)域內(nèi)呈帶分布,具有一定的層位。昌達溝銅礦主要由兩個含銅花崗閃長(斑)巖體組成。礦石以細脈浸染狀為主,浸染狀和脈狀次之,塊狀礦石少見。金屬礦物以黃鐵礦、磁黃鐵礦、含銅黃鐵礦為主,黃銅礦少見。各礦體平均銅品位變化與0.31~1.58%之間,多數(shù)為0.5%左右,屬低品位貧礦;金一般0.1×10-6,少量0.1~0.4(×10-6),個別為26×10-6;礦床規(guī)模為小型。礦體的圍巖蝕變主要出現(xiàn)在巖體本身及接觸帶,主要有鉀化、硅化、絹云母化和綠泥石化,分帶不明顯。該礦床屬于斑巖型銅礦的一個亞類,主成礦階段為熱液期。本文主要研究內(nèi)容包括:區(qū)域地質(zhì)背景、區(qū)域巖漿巖特征、礦床地質(zhì)特征、年代學、礦床地球化學特征、成因探討等。通過以上研究,取得以下成果和認識:(1)昌達溝礦區(qū)花崗閃長斑巖主要屬高鉀鈣堿性系列;巖石鋁質(zhì)含量較高,為典型的過鋁質(zhì)巖石;含礦斑巖鉀質(zhì)含量很高,為典型的鉀質(zhì)巖石系列,這與義敦島弧南段的大型斑巖體的性質(zhì)相似。(2)昌達溝礦區(qū)含礦花崗閃長斑巖的地球化學特征暗示其源區(qū)物質(zhì)來源比較淺,斑巖可能主要由地殼物質(zhì)重熔形成,且可能有少量洋殼物質(zhì)的混染。(3)常量元素特征表明其可能形成于弧環(huán)境(島弧或大陸弧)或大陸碰撞環(huán)境,但與大陸弧環(huán)境最為密切;同時與造山作用密切相關。微量元素特征表明含礦斑巖可能形成于高成熟度的火山弧或陸弧環(huán)境。綜合分析認為,昌達溝銅礦區(qū)含礦花崗閃長斑巖最有可能形成于弧構(gòu)造環(huán)境,并且其可能與大陸弧環(huán)境更為密切。昌達溝斑巖銅礦形成的構(gòu)造環(huán)境與義敦島弧帶南段和中段的普郎、雪雞坪、春都等礦床基本一致。(4)通過鋯石測年顯示昌達溝斑巖體的成巖年齡為208~216Ma,屬于印支期,并非前人所說的燕山期,與義敦島弧南段的普朗、雪雞坪等斑巖體的成巖年代一致。根據(jù)義敦島弧的活動時段250~208Ma,巖漿活動的高峰期在215Ma。(5)長期以來,前人認為義敦島弧北段昌達溝一帶的斑巖體為燕山期,與義敦島弧南段巖漿活動和構(gòu)造環(huán)境存在較大差異,不具備南段形成大型斑巖條件的地質(zhì)背景。本次研究發(fā)現(xiàn),北段昌達溝地區(qū)的斑巖體為印支期,巖體的地質(zhì)地球化學特征與形成時代與南段含礦斑巖體具有很大的相似性,同時也存在與南段斑巖體成礦相似的地質(zhì)背景,因此義敦島弧北段具有較大規(guī)模的斑巖型銅礦的成礦潛力。目前未取得較大突破與工作程度較低有關。
[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.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P618.41

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