本文選題：流紋斑巖 + 鋯石U-Pb定年�。� 參考：《地球?qū)W報》2017年05期

【摘要】：西藏阿里地區(qū)革吉縣乃不扎康巴流紋斑巖是班公湖—怒江成礦帶南緣新發(fā)現(xiàn)的一套次火山巖,本文在地質(zhì)調(diào)查和資料收集的基礎(chǔ)上,開展了流紋斑巖鋯石U-Pb定年和巖石地球化學和鋯石Hf同位素特征研究。流紋斑巖具有高硅(SiO_2=73.93%~74.71%)、高Na_2O+K_2O含量(6.73%~7.30%),低TFe和Mg O含量等特征,屬于弱過鋁質(zhì)高鉀鈣堿性系列且具有I型花崗巖地球化學特征;輕重稀土元素分餾明顯,富集輕稀土元素,具有明顯的負Eu異常,其LREE/HREE值為9.71~12.38,(La/Yb)N值為10.64~14.42,δEu=0.65~0.73;流紋斑巖相對虧損Nb、Ta、Ti等高場強元素,富集Rb、Th、U等大離子親石元素,與典型活動陸源火山巖的微量元素特征類似;LA-ICP-MS鋯石U-Pb定年結(jié)果表明乃不扎康巴流紋斑巖的形成時間為(151.6±1.2)Ma(MSWD=0.9),鋯石εHf(t)值整體為負值( 9.4~2.6,平均為 3.1)且變化范圍較大(可達11個ε單位)呈現(xiàn)出混合源區(qū)特征。Hf同位素數(shù)據(jù)和全巖鋯石飽和溫度(750~791℃)表明幔源物質(zhì)在流紋斑巖形成過程中起到了重要作用。結(jié)合區(qū)域構(gòu)造演化特征,認為該套流紋斑巖主要產(chǎn)于Slainajap洋的南向俯沖的背景之下,由幔源巖漿提供熱量誘發(fā)古老拉薩下地殼發(fā)生部分熔融并與幔源巖漿發(fā)生混合形成初始母巖漿,之后經(jīng)歷一定程度的分離結(jié)晶作用形成。
[Abstract]:The Jiagi County, Jiagi County, Tibet, is a newly discovered subvolcanic rock in the southern margin of the Bangong Lake-Nujiang metallogenic belt. Based on the geological investigation and data collection, Zircon U-Pb dating, geochemistry and HF isotopic characteristics of zircon have been studied in this paper. The fluid-striped porphyry is characterized by high SiOShi (73.931), high Na2O K2O content (6.73K), low TFE and MgO contents, and belongs to the weak peraluminous high-potassium calc-alkaline series and has the geochemical characteristics of I-type granite. The fractionation of heavy and heavy rare earth elements is obvious, and it is rich in light rare earth elements, and is characterized by low TFE and MgO contents, and is characterized by the geochemical characteristics of I-type granites, and the fractionation of heavy and heavy rare earth elements is obvious, and it is rich in light rare earth elements. There are obvious negative EU anomalies with LREE / HREE value of 9.71 ~ 12.38% La- / YbN = 10.64 ~ 14.42, 未 EU ~ (0.65) ~ (0.73) = 0.73. The rhyolitic porphyry is relatively depleted of high field strength elements, such as NB ~ (+) ~ (-) ~ (1), and enriched in RbThU and other large ion lithophile elements, such as RbThU and other large ion lithophile elements. The trace element characteristics similar to those of typical active continental volcanic rocks are similar to those of LA-ICP-MS zircon U-Pb dating. The results show that the formation time of Neibukangba rhyolitic porphyry is 151.6 鹵1.2 Ma-MSWD0. 9, and the zircon 蔚 Hftt is negative as a whole (9. 42.6, average is 3. 1), and the range of variation is large. The HF isotopic data and the zircon saturation temperature of the whole rock indicate that the mantle source material plays an important role in the formation of the rhyolitic porphyry. Combined with the characteristics of regional tectonic evolution, it is considered that this set of fluvial porphyry mainly occurred in the background of southward subduction of the Slainajap Ocean. Heat from mantle magma induces partial melting of the lower crust of ancient Lhasa and mixes with mantle magma to form initial mother magma and then to undergo a certain degree of separation and crystallization.
【作者單位】： 中國地質(zhì)大學(北京)地球科學與資源學院;中國地質(zhì)科學院礦產(chǎn)資源研究所國土資源部成礦作用與資源評價重點實驗室;成都理工大學地球科學學院;
【基金】：中國地質(zhì)調(diào)查局二級項目(編號:DD20160026) 國家自然科學基金項目(編號:41403040)聯(lián)合資助~~
【分類號】：P588.1;P597

【相似文獻】

相關(guān)期刊論文 前8條

1 沈光銀;薛清波;;沽源火山盆地燕山期次流紋斑巖地質(zhì)地球化學特征[J];礦產(chǎn)與地質(zhì);2011年05期

2 黃水保;毛大華;狄永軍;魏英文;羅平;李伯春;;北武夷梨子坑火山盆地流紋斑巖與鉛鋅礦的成因關(guān)系[J];資源調(diào)查與環(huán)境;2012年03期

3 李寧波;單強;張永平;羅勇;楊武斌;姜玉航;于學元;;西天山阿吾拉勒地區(qū)A型流紋斑巖的初步研究[J];大地構(gòu)造與成礦學;2012年04期

4 孫榮祥;黑龍江虎林四平山地區(qū)白堊系流紋斑巖成礦地質(zhì)特征[J];黃金;2002年08期

5 陳志洪;邢光福;姜楊;匡福祥;;華夏陸塊古元古代A型流紋斑巖的發(fā)現(xiàn)及其地質(zhì)意義[J];大地構(gòu)造與成礦學;2013年03期

6 惠衛(wèi)東;朱江;鄧杰;呂新彪;莫亞龍;李春誠;;甘肅北山白山堂礦區(qū)流紋斑巖的U-Pb年代學、地球化學特征及其地質(zhì)意義[J];地質(zhì)與勘探;2013年03期

7 徐軍;汪培儀;;鄞縣鹿山珍珠巖礦理化特征[J];建材地質(zhì);1991年02期

8 朱維光;鐘宏;王立全;何德鋒;任濤;范宏鵬;柏中杰;;云南民樂銅礦床中玄武巖和流紋斑巖的成因:年代學和地球化學制約[J];巖石學報;2011年09期

，

本文編號：2020980