發(fā)布時間：2018-04-01 20:31

  本文選題：MVT鉛鋅礦　切入點：燈影組　出處：《成都理工大學(xué)》2015年碩士論文

【摘要】：四川盆地北緣鉛鋅礦屬于密西西比河谷(MVT)型鉛鋅礦,主要產(chǎn)于燈影組白云巖中。鉛鋅礦床中礦石礦物主要為方鉛礦、閃鋅礦,脈石礦物有螢石、重晶石、瀝青、白云石、方解石、石英,其中螢石、重晶石還可富集形成礦床。本區(qū)MVT型鉛鋅礦與古油(氣)藏在空間上密切共生/伴生,鉛鋅礦成礦與油氣成藏有一定的成因聯(lián)系。本文研究了該區(qū)區(qū)域成礦地質(zhì)背景,借助各種地球化學(xué)分析結(jié)果,得出以下認(rèn)識:(1)該區(qū)寒武系郭家壩組及基底巖石成礦元素背景含量值較高,具有提供成礦物質(zhì)的潛力。(2)礦石的稀土元素配分曲線與該區(qū)基底巖石、寒武系郭家壩組炭質(zhì)泥頁巖、燈影組圍巖相似度低,在稀土元素參數(shù)圖解上礦石與基底巖石、寒武系炭質(zhì)泥頁巖、燈影組圍巖相關(guān)性較差,但寒武系炭質(zhì)泥頁巖與基底巖石卻表現(xiàn)出較好的相關(guān)性。結(jié)合構(gòu)造演化史,得出基底巖石的風(fēng)化剝蝕物質(zhì)為寒武系郭家壩組炭質(zhì)泥頁巖提供了沉積物源。(3)礦石樣品的初始87Sr/86Sr介于0.709782-0.71131,平均值為0.71041,具有殼源特征。這表明基底巖石及寒武系郭家壩組地層都可能為鉛鋅礦提供成礦物質(zhì)。5件硫化物樣品鉛同位素數(shù)據(jù),206Pb/204Pb介于17.62-18.02,207Pb/204Pb介于15.49-15.63,208Pb/204Pb介于37.57-38.35,鉛同位素組成比較穩(wěn)定,屬于正常鉛。由鉛同位素數(shù)據(jù)得出成礦模式年齡418-662Ma,成礦物質(zhì)主要來源于震旦系-寒武系地層。在207Pb/204Pb-206Pb/204Pb、208Pb/204Pb-206Pb/204Pb鉛構(gòu)造演化模式圖及△γ-△β圖解中,數(shù)據(jù)落在地殼和地幔之間,表明其成礦物質(zhì)主要為殼源,但可能有幔源物質(zhì)混入。螢石Sr同位素證據(jù)表明,螢石與白云石具有相同的流體來源,其Ca2+是由圍巖的溶解提供的。研究發(fā)現(xiàn),基底中未發(fā)現(xiàn)延伸到燈影組地層的深大斷裂,燈一段、燈二段白云巖中也未發(fā)現(xiàn)斷裂及礦石礦物的充填,因此成礦物源直接為基底巖石的可能性很小/幾乎沒有。烴源巖寒武系郭家壩組炭質(zhì)泥頁巖是直接的礦源層,而由于基底巖石為寒武系地層提供了沉積物源,基底巖漿巖有些為幔源成因,這也就解釋了Pb同位素圖解中所表現(xiàn)出的幔源物質(zhì)混入的特征。(4)硫同位素數(shù)據(jù)表明,閃鋅礦樣品δ34S介于16-19.4‰,方鉛礦樣品δ34S介于12.94-16.8‰,黃鐵礦樣品δ34S平均值為18.7‰;重晶石樣品δ34S介于32.2-33.48‰。礦石及重晶石表現(xiàn)出富“重硫”特征。與海水及油田鹵水中δ34S值有一定的相似。本文認(rèn)為S與油田鹵水關(guān)系密切,即古油(氣)藏與鉛鋅礦成礦有著密切的關(guān)系。碳同位素數(shù)據(jù)表明,脈石礦物白云石、方解石中Ca2+源于碳酸鹽巖的溶解。(5)本文對螢石、重晶石的來源做了一定的探討,認(rèn)為Ba主要由寒武系郭家壩組提供,Ca主要由圍巖白云巖溶解提供。根據(jù)研究成果,本文討論了鉛鋅礦成礦作用過程,認(rèn)為烴源巖寒武系郭家壩組炭質(zhì)泥頁巖為鉛鋅礦的直接礦源層,基底巖石為間接礦源巖,古油(氣)藏與鉛鋅礦成礦有著一定的耦合關(guān)系。
[Abstract]:The lead-zinc deposit in the northern margin of Sichuan Basin belongs to the Mississippi Valley MVT type lead-zinc deposit, which mainly occurs in dolomite of the Dengying formation. The ore minerals in the lead-zinc deposit are mainly galena, sphalerite, gangue minerals, fluorite, barite, bitumen, dolomite, etc. Calcite, quartz, fluorite and barite can also be enriched to form deposits. The MVT type lead-zinc deposit and paleooil (gas) are closely associated with each other in space. There is a genetic relationship between lead-zinc mineralization and oil and gas accumulation. This paper studies the regional metallogenic geological background in this area, and makes use of various geochemical analysis results. The following conclusions are obtained: (1) the ore-forming element background value of the Cambrian Guojiaba formation and basement rocks in this area is relatively high, and the REE distribution curve of the ore and the carbonaceous shale of the Cambrian Guojiaba formation are also obtained. The similarity of surrounding rock of Dengying formation is low, the correlation between ore and basement rock, Cambrian carbonaceous shale and surrounding rock of Dengying formation is poor in REE parameter diagram. However, the Cambrian carbonaceous shale shows a good correlation with the basement rocks. It is concluded that the weathering and denudation of the basement rocks provide sediment source for the carbonaceous shale of the Cambrian Guojiaba formation. The initial 87Sr/86Sr of the ore samples is between 0.709782-0.71131, with an average value of 0.71041, which indicates that the basement rocks and the Cambrian Guojia family have the characteristics of crust source. The formation of Ba formation may provide lead isotopic data of 5 sulfide samples of ore-forming materials for lead-zinc deposits. The lead isotopic composition of Pb isotopes is relatively stable. The lead isotopic composition is relatively stable. The lead isotopic composition is relatively stable, and the lead isotopic composition is relatively stable, and the lead isotopic composition is relatively stable. The metallogenic model age is 418-662Ma.The ore-forming material is mainly derived from the Sinian to Cambrian strata. In the 207Pb / 204Pb-206Pb / 204Pb / 208Pb / 204Pb-206Pb lead tectonic evolution model map and 緯-尾 diagram, the data fall between the crust and the mantle. The results show that the ore-forming materials are mainly crustal, but mantle-derived materials may be mixed in. The fluorite Sr isotopic evidence shows that fluorite and dolomite have the same fluid source and their Ca2 is provided by the dissolution of surrounding rock. No deep faults extending to the strata of Dengying formation were found in the basement, nor were faults and mineral fillings found in dolomite in the first section of the first section of the lantern formation and the second member of the second stage of the lantern formation. Therefore, there is little possibility that the source rocks are directly basement rocks. The carbonaceous shale of the Cambrian Guojiaba formation of hydrocarbon source rocks is a direct source of ore, whereas the basement rocks provide sediment sources for the Cambrian strata. Some of the basement magmatic rocks are of mantle origin, which explains the characteristics of mantle material mixing in Pb isotopic diagrams. The sulfur isotope data show that the 未 34s of sphalerite samples is between 16-19.4 鈥，

本文編號：1697204