本文關(guān)鍵詞：準(zhǔn)東北石炭系火山巖巖石學(xué)、地球化學(xué)及Lu異常研究　出處：《中國礦業(yè)大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： Lu富集異常 大陸島弧 海底侵入 石炭系火山巖 準(zhǔn)噶爾盆地

【摘要】：準(zhǔn)噶爾盆地東北地區(qū)位于中亞增生造山帶(CAOB)的關(guān)鍵部位,經(jīng)歷了多階段不同性質(zhì)的演化和變革�；鹕綆r巖石學(xué)和地球化學(xué)研究對(duì)地球深部信息提取、限定構(gòu)造演化背景、反演巖漿演化過程具有重要意義。本論文以準(zhǔn)噶爾盆地東北部烏倫古坳陷和陸梁隆起為重點(diǎn)研究區(qū),以英2井、烏參1井、滴北1井、滴北2井等油氣探井鉆遇的石炭系火山熔巖、火山碎屑巖為研究對(duì)象,系統(tǒng)分析了鉆井巖芯、錄井巖屑、地球化學(xué)、測(cè)井和地震等資料,開展了大量巖石薄片鑒定和主量元素、微量元素等地球化學(xué)測(cè)試,探討了該區(qū)石炭系火山巖巖石學(xué)特征及火山巖源區(qū)與構(gòu)造背景,發(fā)現(xiàn)了在該區(qū)石炭系火山巖樣品中存在的顯著Lu富集異常特征,開展了Lu元素富集異常限定的微量元素與稀土元素地球化學(xué)模擬,并討論了其地質(zhì)意義。研究工作取得如下主要成果和認(rèn)識(shí):通過巖石學(xué)研究,將準(zhǔn)噶爾盆地東北部石炭系火山巖劃分為火山熔巖類、火山碎屑巖類、火山沉積巖類三個(gè)巖石類型和爆發(fā)相、噴溢相、火山通道相和火山-沉積相四個(gè)巖相類型。有機(jī)地球化學(xué)信息指示烏倫古坳陷早石炭世處于局限海環(huán)境;在早石炭世晚期,沉積水體發(fā)生顯著咸化,且缺乏陸源有機(jī)質(zhì)的加入;在烏倫古坳陷下石炭統(tǒng)識(shí)別出了浮巖狀熔積巖,是早石炭世晚期烏倫古坳陷存在海底巖漿侵入的直接證據(jù);通過對(duì)沉積背景的研究,將本區(qū)火山-沉積相進(jìn)一步劃分為自碎火山巖沉積亞相、扇三角洲沉積亞相、風(fēng)暴沉積亞相和水下扇沉積亞相四種亞相�；鹕�-沉積相的研究對(duì)該區(qū)的地質(zhì)勘探具有重要啟示。Rb、U、Ba、Sr和Pb等流體活動(dòng)性元素與HFSE、REE流體不活動(dòng)性元素的比值較好地反映了源自俯沖板片的活動(dòng)性元素富集程度。本區(qū)石炭系火山熔巖樣品具有較低的Sr/Nd比和U/Th比,意味著地幔源區(qū)受來自俯沖板片的流體的影響較小;樣品中Y含量較高,Sr/Y較低,明顯不同于俯沖洋殼部分熔融產(chǎn)生的埃達(dá)克熔體,表明俯沖洋殼熔體對(duì)本區(qū)火山熔巖地球化學(xué)組成的貢獻(xiàn)小;而本區(qū)石炭紀(jì)樣品具有較低Ba/Th和較高的Th、Pb含量,同時(shí)具有較低的Ce/Th和Ce/Pb比值,表明本區(qū)石炭系火山熔巖樣品受俯沖板片沉積物熔體影響較大。研究區(qū)樣品具有相對(duì)較高的鎂含量,同時(shí)微量元素和稀土元素分布模式與Setouchi和Ryukyu中部高鎂安山巖類似。綜上所述,本區(qū)石炭系火山熔巖源區(qū)受到俯沖板片上沉積物熔融產(chǎn)生的俯沖板片沉積物熔體的影響較大。微量元素地球化學(xué)特征與構(gòu)造環(huán)境判別圖解指示,準(zhǔn)噶爾盆地東北部石炭系火山巖形成于大陸島弧構(gòu)造環(huán)境。準(zhǔn)噶爾盆地東北地區(qū)石炭紀(jì)火山巖樣品具有顯著的重稀土元素Lu富集異常,這種顯著的Lu富集異常在國內(nèi)外都很罕見。重稀土元素具有極為相近的化學(xué)性質(zhì),在巖漿演化過程中較為穩(wěn)定。Lu富集異常為我們提供了研究巖漿演化過程的重要信息。根據(jù)對(duì)本區(qū)石炭系火山熔巖源區(qū)信息的研究,對(duì)研究區(qū)英2井石炭系火山熔巖樣品進(jìn)行了微量元素與稀土元素地球化學(xué)模擬。模擬結(jié)果與樣品地球化學(xué)特征符合較好,證實(shí)了俯沖板片沉積物熔體加入了地幔源區(qū),并對(duì)該區(qū)石炭系火山巖樣品的物質(zhì)組成做出了貢獻(xiàn)。因此Lu富集異�？梢宰鳛槭考o(jì)準(zhǔn)噶爾盆地卡拉麥里縫合線及其沿長(zhǎng)線附近俯沖沉積物熔體加入島弧火山巖巖漿源區(qū)的重要識(shí)別指標(biāo)。
[Abstract]:In the northeastern Junggar basin is located in the central accretionary orogenic belt (CAOB) is the key part, multiple stages of the different nature of evolution and change. The deep information of petrology and geochemistry of the volcano on earth extraction, defined tectonic background, inversion of magma evolution has important significance. This paper takes Junggar basin in the northeast of ancient Wulun depression and Luliang Uplift as the key research area, to the British 2 black and 1 wells, wells, Dibei 1 wells, 2 wells of oil and gas in Dibei drilled Carboniferous volcano lava and volcano clastic rocks as the research object, systematic analysis of drilling cores, logging cuttings, geochemistry, logging and seismic the data, carried out a large number of rock slices identification and major elements, trace elements and geochemical testing, discusses the Carboniferous volcano rocks and source rocks and volcano tectonic background, found in the Carboniferous volcano rock In the presence of significant Lu enrichment anomaly, the trace elements and REE geochemical simulation of Lu enrichment anomaly defined, and discusses its geological significance. The research work made the following main achievements: through petrological study, the northeastern Junggar basin the Carboniferous volcano rocks into volcano lava and volcano clastic rock type, volcano sedimentary rocks of three types of rock and explosive facies, effusive facies, volcano and volcano - sedimentary facies Channel Four lithofacies types. Organic geochemical information indicating the Wulungu depression of Early Carboniferous in the restricted sea environment; in the late Early Carboniferous, significant sedimentary water salinization, and lack of terrigenous join organic matter; in the Wulungu depression of Lower Carboniferous identified pumice like peperite, is late Early Carboniferous Wulungu depression direct evidence for the existence of magma intrusion through the seafloor; sedimentary background The research in this area can be further divided into volcano - sedimentary facies autoclastic volcano sedimentary facies, fan delta subfacies, storm sedimentary subfacies and subaqueous fan subfacies four subfacies. Facies of volcano sedimentary has important implications for geological exploration in this area.Rb, U, Ba. Sr and Pb activities of fluid elements and HFSE, the ratio of REE fluid activity elements reflect the activity of the elements from the subducted slab. The enrichment degree of Carboniferous volcano lava samples with low Sr/Nd ratio and U/Th ratio, means that the mantle source region is less affected by fluid from subducted slab the Y content in the sample; high, low Sr/Y, significantly different adakitic melts from partial melting of subducted oceanic crust produced, showed that the subducted oceanic crust melt in this region the volcano lava geochemical composition contribution is small; while the region of Carboniferous samples with low Ba/Th and high Th, containing Pb At the same time, with the lower Ce/Th and Ce/Pb ratios, indicating that this region of Carboniferous volcano lava samples by subducted sedimentary melt influence. Samples of the study area has a relatively high content of magnesium, and trace elements and rare earth elements and the distribution patterns of central Setouchi and Ryukyu high Mg andesite is similar. In summary, the Carboniferous volcano the source of the lava area affected by the subducting slab on the sediment melt produced by subduction sediment melt greatly. Trace element geochemical characteristics and tectonic setting discrimination diagrams indicate that the Carboniferous volcano rocks in the northeastern Junggar basin formed in a continental island arc tectonic environment. The Carboniferous volcano rock samples in the northeastern Junggar basin has significant enrichment of heavy rare earth elements Lu this anomaly, significant Lu enrichment anomaly at home and abroad are very rare. The heavy rare earth elements have very similar chemical properties, in the magma The evolution of stable.Lu enrichment anomaly provides us with important information on the evolution process of magma. According to the study of the Carboniferous volcano lava information source, the study area well Ying 2 Carboniferous volcano lava samples of trace elements and REE geochemical simulation. The simulation results and the samples with geochemical characteristics well, that subducted sedimentary melt into the mantle source region, and the Carboniferous volcano rock samples of material composition and make a contribution. So Lu can be used as enrichment anomaly in Junggar Basin Carboniferous Kalamaili suture and the important index to identify long-term near subducted sedimentary melt into island arc volcano magma source region.

【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：P588.14

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本文編號(hào)：1372710