本文選題：江西銅山-船坑　切入點：中酸性侵入巖　出處：《成都理工大學(xué)》2017年碩士論文

【摘要】：銅山-船坑中酸性侵入巖產(chǎn)出于欽杭結(jié)合帶東段,華夏板塊北西緣,位于萍鄉(xiāng)-廣豐-江山-紹興超殼深大斷裂帶北西側(cè)。研究區(qū)圍巖地層單一,主要發(fā)育北東向斷裂,三疊系地層經(jīng)印支期運動發(fā)生褶皺,形成一系列倒轉(zhuǎn)背、向斜復(fù)式褶皺。銅山-船坑中酸性侵入巖巖石類型主要有石英閃長玢巖和花崗閃長斑巖。石英閃長玢巖:斑晶主要為斜長石、角閃石和堿性長石,以及極少量黑云母或石英斑晶;基質(zhì)成分主要由微晶長英質(zhì)礦物和隱晶質(zhì)物質(zhì)組成�；◢忛W長斑巖:斑晶主要由斜長石、堿性長石、石英組成,角閃石和黑云母含量較少;基質(zhì)為全晶質(zhì),主要由石英和長石微細晶組成。石英閃長玢巖在巖漿分離結(jié)晶作用中先于花崗閃長斑巖侵位成巖:石英閃長玢巖和花崗閃長斑巖有明顯的巖相分異界線;與花崗閃長斑巖接觸帶的石英閃長玢巖一側(cè)發(fā)育烘烤硅化邊;可見花崗閃長斑巖脈穿插進石英閃長玢巖脈中;兩者接觸帶的構(gòu)造作用僅使石英閃長玢巖組成礦物發(fā)生變質(zhì)變形現(xiàn)象。銅山-船坑中酸性侵入巖具有類弧型地球化學(xué)特征,屬于廣義的鈣堿性性偏鋁質(zhì)-過鋁質(zhì)花崗巖系列,高CaO、K_2O和低Na_2O,A/CNK值小于1.1,里特曼指數(shù)(σ)小于1.8;富集Rb、Ba、Th和U等大離子親石元素(LILF),強烈虧損Ta、Nb和Ti等高場強元素(HFSE);輕重稀土分異明顯,富集輕稀土、虧損重稀土,無明顯Eu負異常,稀土元素配分為向右陡傾型。銅山-船坑中酸性侵入巖為埃達克質(zhì)I型花崗巖類。原生巖漿為增厚下地殼物質(zhì)角閃榴輝巖重熔形成,“繼承”了新元古代形成的弧型巖石的地球化學(xué)特征,巖漿源區(qū)位于地殼50km以下,殘留相主要為角閃石,其次為石榴石,并且有穩(wěn)定的金紅石殘留相。MgO#值總體偏低(平均為0.41),且MgO、Ni和Cr含量總體較低,FeO/MgO值較高,表明原生巖漿受地幔橄欖巖混染極少;同時略高于大陸地殼的Nb/Ta值(平均為13.8),表明重熔巖漿有地幔物質(zhì)的加入。在古太平洋板塊斜向俯沖擠壓構(gòu)造體系的擠壓松弛階段,增厚下地殼部分重熔形成的埃達克質(zhì)巖漿在穿越上地幔的過程中加入了極少量地幔物質(zhì)后,“殼�；煸础睅r漿沿萍鄉(xiāng)—廣豐—江山—紹興超殼深大斷裂向地表運移,在地表淺部沿北東-南西向斷裂和褶皺構(gòu)造系統(tǒng)以及巖層脆弱面分流侵位,最終形成了銅山-船坑中酸性侵入巖帶。銅山-船坑中酸性侵入巖成巖年齡為171±1.6 Ma(n=15,MSWD=0.16)與德興銅礦成礦巖體成巖年齡171±3 Ma基本一致,兩者有相似的原生巖漿來源,均為埃達克質(zhì)I型花崗類,都具有類弧型巖石地球化學(xué)特征。而且中酸性侵入巖Cu、Mo、Zn等元素含量遠高于背景值,主要來源于成巖原生巖漿,這也與德興銅礦成礦物質(zhì)來源相似。說明研究區(qū)中酸性侵入巖有良好的含礦性。銅山-船坑地區(qū)基本具備了斑巖型銅礦的成礦物質(zhì)來源、巖漿運移通道、導(dǎo)礦和容礦空間以及圍巖條件等因素,成礦條件優(yōu)越,成礦潛力巨大。
[Abstract]:Tongshan-Chuankeng intermediate-acid intrusive rocks occurred in the eastern section of Qinghang binding belt, the western northern margin of the Huaxia plate, located in the north west of Pingxiang-Guangfeng-Jiangshan-Shaoxing super crust deep fault zone. The surrounding rock strata in the study area are single and mainly developed NE trending faults. The Triassic strata fold over the Indosinian movement, forming a series of inversion backs. The main rock types of Tongshan-Chuankeng intermediate-acid intrusive rocks are quartz diorite porphyrite and granodiorite porphyry. Quartz diorite porphyrite: porphyry is mainly plagioclase, hornblende and alkaline feldspar. The matrix is mainly composed of microcrystalline feldspar minerals and cryptonite. Granodiorite: porphyry is mainly composed of plagioclase, alkaline feldspar, quartz, hornblende and biotite. Quartz diorite porphyrite was prior to granodiorite emplacement diagenesis during magmatic separation and crystallization: quartz diorite porphyrite and granodiorite porphyry had distinct lithofacies differentiation lines. On the side of quartz diorite porphyrite in contact zone with granodiorite porphyry, bake siliconized edge is developed, and the granodiorite porphyry vein is inserted into quartz diorite porphyrite vein. The tectonics of the two contact zones only resulted in metamorphic deformation of the minerals of quartz diorite porphyrite. Tongshan-Chuankeng intermediate-acid intrusive rocks have arc-like geochemical characteristics and belong to the generalized calc-alkaline metamorphic and peraluminous granite series. The CNK values of high CaOK2O and low Na2OO are less than 1.1, and the Ritman index (蟽) is less than 1.8; the enrichment of large ion lithophile elements, such as RbPBA, Th and U, and the strong depletion of high field strength elements such as TaNb and Ti; the difference of light rare earths, the enrichment of light rare earths, the loss of heavy rare earths, and no obvious negative EU anomalies. The distribution of rare earth elements is divided into right-dip steep dip type. Tongshan-Chuankeng intermediate-acid intrusive rock is adakitic type I granite. Primary magma is formed by thickening the lower crust material, hornblende eclogite remelting, which "inherits" the arc formed from Neoproterozoic. Geochemical characteristics of the type type rocks, The magmatic source region is located below 50km in the crust, and the residual phase is mainly amphibole, followed by garnet, and there is a stable rutile residual phase. The value of .MgO # is relatively low (average 0.41%), and the content of MgOO, Ni and Cr is relatively low, and the value of Feo / MgO is relatively high. The results show that primary magma is rarely mixed with mantle peridotite, and is slightly higher than the Nb/Ta value of continental crust (mean 13.8g), indicating that the remelted magma has the addition of mantle material. At the stage of compressional relaxation of the paleo-Pacific plate oblique subduction compressional tectonic system, The adakitic magma formed by partial remelting of the thickened lower crust added a very small amount of mantle material through the upper mantle, and the "crust and mantle mixed source" magma migrated to the surface along the deep faults of Pingxiang, Guangfeng, Jiangshan and Shaoxing supercrusts. In the shallow part of the surface along the NSE trending faults and fold tectonic systems and the distributary emplacement of the fragile surface of the strata, Finally, the Tongshan-Chuankeng intermediate-acid intrusive rock belt was formed. The diagenetic age of the Tongshan-Chuankeng intermediate-acid intrusive rock is 171 鹵1.6 Ma / 15 MSWDN 0.16) and the diagenetic age of the Dexing copper ore-forming body is 171 鹵3 Ma, which has similar primary magma source. All of them are adakitic type I granitic, all of them have arc-like petrogeochemical characteristics, and the contents of Cu, Mo, Zn and other elements in the intermediate-acid intrusive rocks are much higher than the background values, and are mainly derived from the diagenetic primary magma. This is similar to the source of ore-forming material in Dexing Copper Mine. It shows that the intermediate-acid intrusive rocks in the study area have good ore-bearing properties. The Tongshan-Chuankeng area basically has the source of ore-forming materials of porphyry copper deposits and the channel of magma migration. The ore-forming conditions are superior and the ore-forming potential is great.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P588.12;P611

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