發(fā)布時間：2018-04-28 09:55

  本文選題：滇西 + 巖漿類型�。� 參考：《中國地質(zhì)大學(北京)》2017年博士論文

【摘要】：研究區(qū)位于三江地區(qū)富堿侵入巖帶上,銅礦體主要產(chǎn)于斑巖體及其外圍接觸帶,礦化與斑巖體密切相關。本文以筆架山、小龍?zhí)�、分水嶺三個典型斑巖型Cu多金屬礦床為研究對象,在詳細的野外地質(zhì)調(diào)查的基礎上,運用鋯石LA-MC-ICP-MS U-Pb同位素年代學方法探討了研究區(qū)典型斑巖型Cu多金屬礦床的成巖、成礦時代;運用巖石學、地球化學分析,探討了研究區(qū)成礦斑巖體的巖漿成因類型;運用Lu-Hf同位素方法,探討了研究區(qū)成礦斑巖體的巖漿來源;以電子探針分析結果為基礎,運用角閃石—斜長石地質(zhì)溫壓計推算了研究區(qū)成礦斑巖體的巖漿侵位深度,并探討了成礦巖體的剝蝕程度;最終,綜合野外觀測及實驗數(shù)據(jù)分析,討論了礦床的成因、成礦地質(zhì)體特征、成礦構造與成礦結構面、成礦作用特征標志,構建了成礦地質(zhì)模型,以期為滇西地區(qū)斑巖型銅礦找礦工作提供一定理論指導。對研究區(qū)三個典型礦區(qū)主要侵入巖開展了全巖地球化學、鋯石LA-ICP-MS U-Pb年代學和Hf同位素研究,獲得含礦二長斑巖的206Pb/238U加權平均年齡分別為:筆架山35.6±0.2Ma,小龍?zhí)?6.0±0.2Ma,分水嶺36.0±0.2Ma,表明研究區(qū)斑巖體為始新世巖漿活動的產(chǎn)物。巖體Si O2含量變化較大,高鉀、富堿,屬鈣堿性—堿性(少量過堿性)、準鋁質(zhì)—過鋁質(zhì)巖石;富集大離子親石元素(K、Rb、Ba、La、Nd)、虧損高場強元素(Ta、Nb、Sr、P、Ti),富集輕稀土元素、虧損重稀土元素;雖被劃入富堿侵入巖及A型花崗巖斑巖礦床,但具C型埃達克巖地球化學特征。斑巖體鋯石εHf(t)值變化較大,顯示研究區(qū)始新世斑巖體來源于下地殼物質(zhì)的部分熔融,并有幔源物質(zhì)的加入。應用電子探針分析和角閃石—斜長石溫壓計獲得滇西典型銅多金屬礦區(qū)出露于地表的斑巖體結晶溫壓分別為:筆架山833.99℃,284.18 MPa;小龍?zhí)?04.72℃,163.88MPa;分水嶺748.67℃,116.70MPa;進而得出研究區(qū)斑巖體侵位深度變化較大,筆架山巖體平均為10.53km,小龍?zhí)?.07km,分水嶺4.33km,顯示從南西到北東侵位越來越淺的趨勢。成礦模式總結為“斑巖侵位,次級構造,熱流循環(huán),接觸交代,表生富集,再生成礦”。結合區(qū)域演化特征,認為研究區(qū)斑巖體形成于造山期后的拉張環(huán)境,陸陸碰撞擠壓后應力松馳,巖漿沿斷裂及次級斷裂上侵,進而形成銅多金屬礦床。
[Abstract]:The study area is located in the alkali-rich intrusive rock belt in Sanjiang area, and the copper ore body mainly occurs in the porphyry and its peripheral contact zone, and the mineralization is closely related to the porphyry. In this paper, three typical porphyry Cu polymetallic deposits, Bijiashan, Xiaolongtan and watershed, are taken as research objects, and on the basis of detailed field geological survey, The diagenesis and metallogenic age of typical porphyry Cu polymetallic deposits in the study area are discussed by means of zircon LA-MC-ICP-MS U-Pb isotopic chronology, and the magmatic genetic types of ore-forming porphyry bodies in the study area are discussed by means of petrology and geochemical analysis. The magma source of the ore-forming porphyry in the study area is discussed by using Lu-Hf isotope method, and the magmatic emplacement depth of the ore-forming porphyry body in the study area is calculated by using the hornblende plagioclase thermometer based on the results of electron probe analysis. The denudation degree of ore-forming rock mass is discussed, and finally, the genesis of ore deposit, the characteristics of ore-forming geological body, metallogenic structure and ore-forming structure plane, and the characteristics of metallogenic process are discussed by synthesizing field observation and experimental data analysis. A metallogenic geological model is constructed to provide theoretical guidance for porphyry copper deposit prospecting in western Yunnan. The whole rock geochemistry, zircon LA-ICP-MS U-Pb chronology and HF isotopic studies have been carried out on the main intrusive rocks in three typical ore areas in the study area. The 206Pb/238U weighted mean ages of the porphyry are respectively: Bijiashan 35.6 鹵0.2Ma, Xiaolongtan 36.0 鹵0.2Ma, watershed 36.0 鹵0.2Ma. this indicates that the porphyry in the study area is the product of Eocene magmatic activity. The content of Sio _ 2 in the rock mass varies greatly and is high in potassium and alkali, belonging to calc-alkaline-alkaline (a small amount of peralkaline, quasi-aluminum-peraluminous rock), rich in large ion lipophilic elements (K ~ (+) Rb ~ (+) B _ (+) La _ (+) NdN _ (+), and depleted in the high field strength element (Tao Nb _ (B) _ (Sr _ (+) _ (P _ (+) _ (Ti), enriched in light rare earth elements and depleted in heavy Although it has been classified into alkali-rich intrusive rocks and A-type granite porphyry deposits, it has the geochemical characteristics of C type adakite. The zircon 蔚 HF t) values of the porphyry body vary greatly, indicating that the Eocene porphyry body in the study area originated from the partial melting of the lower crustal material with the addition of mantle-derived material. Using electron probe analysis and hornblende plagioclase thermometer, the crystallization temperature and pressure of porphyry rock exposed to the surface of typical copper polymetallic mining areas in western Yunnan were obtained as follows: Bijiashan 833.99 鈩，

本文編號：1814779