本文選題：火山巖　切入點(diǎn)：地球化學(xué)　出處：《新疆大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本文著重從巖石學(xué)、地球化學(xué)角度對(duì)喀納斯地區(qū)早古生代火山巖進(jìn)行系統(tǒng)的討論,同時(shí)對(duì)火山巖的分布組合、形成環(huán)境及形成時(shí)代進(jìn)行了探討和全面認(rèn)識(shí)。借助地球化學(xué)數(shù)據(jù)的分析和對(duì)比研究為該區(qū)古生代地質(zhì)演化研究提供重要的依據(jù)�？{斯地區(qū)發(fā)育一套火山-沉積地層?xùn)|錫勒克組,由于缺少可靠的年齡和地球化學(xué)數(shù)據(jù),使其形成時(shí)代及地球動(dòng)力學(xué)背景長(zhǎng)期存在爭(zhēng)議。為探討這一問(wèn)題,本次工作選擇區(qū)內(nèi)火山巖作為研究對(duì)象,對(duì)糜棱巖化英安巖進(jìn)行鋯石LA-ICPMS U-Pb同位素定年,得到兩個(gè)樣品的~(206)U/~(238)Pb年齡分別為445.4±3.1Ma和445.7±3.7Ma,代表火山巖結(jié)晶年齡為晚奧陶世。這表明東錫勒克組地層形成于晚奧陶世。火山巖SiO_2含量為53.99%~71.04%,具有富鋁(Al_2O_3=13.83%~16.27%),貧鎂(MgO=1.09%~3.53%),K_2O介于1.11%~3.83%之間,平均為2.84%,屬于高鉀質(zhì)火山巖系列的特征。輕稀土富集,Eu負(fù)異常(δEu=0.65~0.82);巖石地球化學(xué)研究表明,火山巖富集大離子親石元素(Rb、Th、Ce)和虧損高場(chǎng)強(qiáng)元素(K、Nb、Ta),具有島弧火山巖特征。結(jié)合區(qū)域資料及本文成果,筆者認(rèn)為,該套火山巖形成于活動(dòng)大陸邊緣洋殼俯沖消減后期同碰撞的環(huán)境。晚奧陶世末古亞洲洋由南向北向西伯利亞板塊之下俯沖形成具有活動(dòng)大陸邊緣弧性質(zhì)的喀納斯地區(qū)晚奧陶世火山巖。
[Abstract]:In this paper, the early Paleozoic volcanic rocks in Kanas area are systematically discussed from the viewpoint of petrology and geochemistry, and the distribution and assemblage of volcanic rocks are also discussed. The formation environment and age of formation are discussed and fully understood. The analysis and comparative study of geochemical data provide an important basis for the study of Paleozoic geological evolution. A set of volcanic-sedimentary development in Kanas area. Formation of East Sirk formation, Due to the lack of reliable age and geochemical data, the age of formation and geodynamic background have been disputed for a long time. In order to study this problem, volcanic rocks in this area are selected as the research objects. Zircon LA-ICPMS U-Pb isotopic dating of mylonitic dolomite is carried out. The two samples were obtained at the ages of 445.4 鹵3.1 Ma and 445.7 鹵3.7 Ma, respectively, representing the crystallization age of the volcanic rocks in the late Ordovician. This indicates that the formation of the East Silerk formation was formed in the late Ordovician. The SiO_2 content of the volcanic rocks is 53.990.74, and the SiO_2 content of the volcanic rocks is 53.990.The SiO_2 content of the volcanic rocks is 53.9971.04, and the Al2O3-rich Al _ 2O _ 2O _ (13.83N) is 16.2727, and the MgO1.093.53K _ 2O is between 1.113.83% and 1.113.83%. The average value is 2.84, which belongs to the characteristics of high-potassium volcanic rock series. LREE is enriched with negative EU anomaly (未 EU _ (0.65) ~ 0.82 ~ (g)). Volcanic rocks are rich in large ion lithophile elements RbSe (Th) and depleted elements of high field strength (KNB) Taan, which are characterized by island arc volcanic rocks. In combination with regional data and the results of this paper, the authors believe that, The volcanic rocks were formed in the colliding environment during the late subduction and subduction of the active continental margin oceanic crust. The late Ordovician Paleo-Asian Ocean subducted from south to north to Siberia plate to form Kanas with active continental margin arc. Late Ordovician volcanic rocks in the region.
【學(xué)位授予單位】：新疆大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P588.14

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本文編號(hào)：1558529