本文選題：火山巖　切入點(diǎn)：安山玢巖　出處：《巖石學(xué)報(bào)》2017年02期 　論文類型：期刊論文

【摘要】：寧蕪中生代火山盆地廣泛產(chǎn)出早白堊世中基性火山巖,鉀質(zhì)巖石主要為龍王山組英安巖、粗安巖,鈉質(zhì)火山巖主要為大王山組玄武粗安巖、粗安巖、英安巖以及鈉質(zhì)安山玢巖類。鈉質(zhì)輝石安山玢巖的鋯石U-Pb年齡為128.9±1.9Ma,為早白堊世產(chǎn)物。稀土元素球粒隕石標(biāo)準(zhǔn)化配分曲線均表現(xiàn)為一致的平緩右傾型式,Eu負(fù)異常不明顯,富集大離子親石元素,虧損高場(chǎng)強(qiáng)元素,具Nb、Ta的負(fù)異常。鉀質(zhì)龍王山組火山巖總體Cs、Rb、Ba、Th、U等LILE含量較鈉質(zhì)大王山組火山巖和鈉質(zhì)安山玢巖高,并具有較高的Si、K,較低的Ca、Mg,高Rb/Sr,高Isr(0.70521~0.70857);鈉質(zhì)火山巖具有較低的Si、富Na、高Sr、低I_(sr)(0.70544~0.70768),Mg~#相對(duì)較高。鈉質(zhì)輝石閃長玢巖斑晶中有斜長石的礦物結(jié)構(gòu)和成分不平衡現(xiàn)象,鋯石Hf同位素特征為ε_(tái)(Hf)(t)=-6.2~+0.6,變化較大,指示巖漿混合過程。地幔源區(qū)可能是由中元古代俯沖板塊釋放出流體發(fā)生交代作用后形成的富集地幔,鉀質(zhì)火山巖地幔源區(qū)交代礦物可能以金云母為主,崆嶺群TTG片麻巖為其地殼端元。而鈉質(zhì)火山巖地幔源區(qū)交代礦物可能以角閃石和單斜輝石為主,中元古上溪群變質(zhì)基性巖或新生下地殼基性巖為其地殼端元。
[Abstract]:In the early Cretaceous Mesozoic volcanic rocks, the potash rocks are mainly composed of Longwangshan formation, trachyandesite and sodium volcanic rocks, which are mainly composed of Black Tortoise trachyandesite and trachyandesite of the Dawangshan formation. The zircon U-Pb age of sodium pyroxene andesite porphyrite is 128.9 鹵1.9 Ma. it is the product of early Cretaceous. The standardized distribution curves of chondrites of rare earth elements all show that the flat right-dip type of EU negative anomaly is not obvious. It is enriched in large ion lithophile elements, depleted in high field strength elements, and has negative anomalies of NB Ta. The total LILE content of volcanic rocks of the potassium Longwangshan formation is higher than that of sodium Dawangshan formation volcanic rocks and sodium anandesite porphyrite, and the total LILE content of the volcanic rocks of the kalium Longwangshan formation is higher than that of sodium dawangshan formation. It also has higher Si-K, lower Ca-Mg, higher RB / Sr, higher Isrn 0.70521 + 0.70857, and lower Si-rich, Na-rich, high-Sr-0.705440.70768 Mg#. The mineral structure and composition of plagioclase in porphyrite porphyry of sodium pyroxene are unbalanced, and the mineral structure and composition of plagioclase are out of balance in the porphyrite porphyrite of sodium pyroxene, and the mineral structure and composition of plagioclase are unbalanced in the porphyry of sodium pyroxene, and the mineral structure and composition of plagioclase in the porphyry of sodium pyroxene are not balanced. The isotopic characteristics of zircon HF are 蔚 ~ (-1) HflT ~ (-2) -6.2 ~ 0.6, indicating the magmatic mixing process. The mantle source region may be a enriched mantle formed by the metasomatism of the fluid released from the Mesoproterozoic subduction plate. The metasomatic minerals in the mantle source of the potash volcanic rocks may be mainly phlogopite, while the TTG gneiss of the Kongling group are the end elements of the crust, while the metasomatic minerals in the mantle source of the sodium volcanic rocks may be mainly amphibole and clinopyroxene. Metamorphic basic rocks of Mesoproterozoic Upper Stream Group or Neo-Lower crustal basic rocks are the end elements of their crust.
【作者單位】： 桂林理工大學(xué)地球科學(xué)學(xué)院;北京大學(xué)地球與空間科學(xué)學(xué)院;合肥工業(yè)大學(xué)資源與環(huán)境工程學(xué)院;
【基金】：國家自然科學(xué)基金項(xiàng)目(41530206) 桂林理工大學(xué)科研啟動(dòng)費(fèi)資助項(xiàng)目聯(lián)合資助
【分類號(hào)】：P588.14

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