本文關(guān)鍵詞： 氧、硫、鉛同位素 成礦物質(zhì)來源 礦床成因 大排鐵鉛鋅礦床 福建閩西南　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：閩西南大排鐵鉛鋅多金屬礦床位于福建閩西南坳陷帶南緣,大地構(gòu)造位置上位于華南板塊東部,該區(qū)經(jīng)歷了復(fù)雜的構(gòu)造巖漿演化過程,尤其中生代以來,強(qiáng)烈的構(gòu)造巖漿活動(dòng)在該區(qū)表現(xiàn)的尤為突出,并伴隨有大量的晚中生代花崗質(zhì)侵入巖在該區(qū)分布�！榜R坑式”鐵礦床在閩西南地區(qū)呈帶狀大面積分布,其成因備受地質(zhì)同仁的關(guān)注,為探索該區(qū)“馬坑式”鐵多金屬礦床的成因機(jī)制,有必要從同位素角度探討成礦物質(zhì)來源并進(jìn)一步分析其對(duì)閩西南“馬坑式”鐵礦成因的指示意義。大排礦床是閩西南地區(qū)新發(fā)現(xiàn)的鐵鉛鋅多金屬礦床,同時(shí)也是“馬坑式”代表性鐵礦床之一,對(duì)其開展研究工作很有必要。大排礦床礦體主要賦存于該區(qū)碳酸鹽巖層位中,一系列淺層次逆沖推覆構(gòu)造及層間滑脫構(gòu)造帶為其主要的控礦構(gòu)造,與成礦關(guān)系密切的巖漿巖主要為中細(xì)粒似斑狀花崗閃長(zhǎng)巖,其與圍巖碳酸鹽巖的接觸帶附近常伴隨有矽卡巖化、碳酸鹽化、硅化等蝕變。礦床的形成主要經(jīng)歷了早期矽卡巖階段、磁鐵礦階段、石英-硫化物階段及晚期碳酸鹽階段,其中磁鐵礦階段及石英硫化物階段為大排鐵鉛鋅多金屬礦床主要的成礦階段,礦床具典型矽卡巖礦床的成礦特征。本文在對(duì)閩西南大排鐵鉛鋅多金屬礦床地質(zhì)特征調(diào)查的基礎(chǔ)上,分別開展了礦石中主要礦物磁鐵礦、石榴子石的氧同位素及黃鐵礦、閃鋅礦和方鉛礦的硫、鉛同位素測(cè)試。結(jié)果表明,石榴子石中δ18O值變化范圍為3.4~6‰,與正�；◢弾r的的氧同位素十分接近,暗示可能繼承了該區(qū)花崗質(zhì)侵入巖的的同位素組成;根據(jù)磁鐵礦的氧同位素組成(2.2~4.3‰)所計(jì)算的磁鐵礦階段成礦流體的δ18O為9.23~11.34‰(500℃)或8.58~10.69‰(600℃),表明在成礦流體中有含較多δ18O的CO2加入。礦石硫化物δ34S組成變化范圍較窄,變化范圍為-2.6~1.5‰,多數(shù)集中在0值左右,具有巖漿硫(0±3‰)的特點(diǎn)。硫化物的鉛同位素組成206Pb/204Pb、207Pb/204Pb、208Pb/204Pb的數(shù)值分別為18.486~18.537、15.665~15.712、38.823~38.979,鉛同位素比值變化范圍小,整體上具有殼幔混合且以殼源物質(zhì)為主的特點(diǎn)。結(jié)合對(duì)閩西南“馬坑式”鐵多金屬礦床及閩西南花崗巖年代學(xué)討論,認(rèn)為大排鐵鉛鋅多金屬礦床的形成主要與晚中生代(~130Ma)花崗質(zhì)巖漿侵入作用有關(guān)。
[Abstract]:The Fe-Pb-Zn polymetallic deposit is located in the southern margin of southwestern Fujian depression, and the tectonic position is located in the eastern part of South China plate. The area has undergone complicated tectonic magma evolution process, especially since Mesozoic. The strong tectonic magma activity is especially prominent in this area, and accompanied by a large number of late Mesozoic granitic intrusive rocks in the area. In order to explore the genetic mechanism of the "Ma Hang type" iron polymetallic deposit in this area, It is necessary to probe into the source of ore-forming materials from the perspective of isotopes and to further analyze its indicative significance to the genesis of "maqing-type" iron ore deposits in southwestern Fujian, where the Dapai deposit is a newly discovered iron-lead-zinc polymetallic deposit. At the same time, it is also one of the representative iron ore deposits of "Ma-Peng" type, so it is necessary to carry out research work on them. The ore bodies of Dapai deposit mainly occur in the carbonate strata in this area. A series of shallow thrust-nappe structures and interlayer slip belts are the main ore-controlling structures, and the magmatic rocks closely related to mineralization are mainly meso-fine-grained porphyry granodiorite. The contact zone between the deposit and the surrounding rock carbonate rocks is often accompanied by skarnization, carbonization, silicification and other alteration. The formation of the deposit mainly experienced the early skarn stage, the magnetite stage, the quartz-sulfide stage and the late carbonate stage. The magnetite stage and quartz sulfide stage are the main metallogenic stages of the Da-Pai Fe-Pb-Zn polymetallic deposit. The ore deposit has the metallogenic characteristics of typical skarn deposits. Based on the investigation of the geological characteristics of the Dadai iron, lead and zinc polymetallic deposits in the west of Fujian, the oxygen isotopes and pyrite of the main minerals magnetite, pomegranate and pyrite in the ore have been developed respectively. The sulfur and lead isotopes of sphalerite and galena are tested. The results show that the 未 18O value of pomegranate varies from 3.4 to 6 鈥，

本文編號(hào)：1536752