【摘要】：在現(xiàn)今活動(dòng)的俯沖帶系統(tǒng)中,俯沖板片的后撤或回卷都可能導(dǎo)致弧前伸展作用,但弧前伸展作用是否局限于淺部構(gòu)造層次,還是涉及整個(gè)巖石圈,是理解島弧構(gòu)造演化和地球化學(xué)效應(yīng)的重要課題。在西藏岡底斯巖基南緣,保留著世界上典型的弧前盆地——日喀則弧前盆地。在該盆地的北緣,除了發(fā)育中新世閃長(zhǎng)玢巖脈外,還發(fā)育一系列近東西向展布的輝綠巖脈,形成時(shí)代為106.6±0.8Ma(鋯石U-Pb年齡)�；詭r脈在巖石學(xué)、礦物學(xué)和地球化學(xué)特征上較均一,具體表現(xiàn)為:(1)富集LREE,虧損HREE,但HREE平直;(2)強(qiáng)烈虧損Rb、Ba、Nb和Ta,微弱虧損Ti,但Zr和Hf不具虧損現(xiàn)象;(3)鋯石Hf同位素組成(εHf(t)=+11.7~+15.4)較高;和(4)包含捕獲的早侏羅世巖漿鋯石。上述數(shù)據(jù)表明:在日喀則弧前盆地形成過(guò)程中,伴隨著強(qiáng)烈的早白堊紀(jì)弧前伸展作用,誘發(fā)較虧損地幔發(fā)生部分熔融,形成不同于典型島弧巖漿巖的基性巖,可能是在新特提斯洋北向俯沖過(guò)程中,海溝后撤,在弧前形成強(qiáng)烈的地幔角流的結(jié)果。同時(shí),日喀則弧前盆地可能構(gòu)建于早侏羅紀(jì)結(jié)晶巖系之上。
[Abstract]:In the present active subduction zone system, the retreating or rewinding of the subduction plate may lead to the prearc extension, but whether the prearc extension is confined to the shallow tectonic level or involves the whole lithosphere, It is an important subject to understand the tectonic evolution and geochemical effects of island arc. In the southern margin of the Gangdis rock base in Tibet, the world's typical forearc basin-Xigaze forearc basin is preserved. In the northern margin of the basin, in addition to the developing diorite porphyrite veins, a series of near east-west diabase veins have been developed. The age of formation is 106.6 鹵0.8Ma (U-Pb age of zircon). The basic veins are more homogeneous in petrology, mineralogy and geochemistry, The main results are as follows: (1) rich in LREE, depleted in hree, but flat in HREE; (2) strongly depleted in RbbBaNb and Ta, with weak depletion of Ti, but not depleted in Zr and HF; (3) higher in zircon HF isotopic composition (蔚 Hf (t) = 11.7 ~ 15.4); and (4) containing trapped early Jurassic magmatic zircon. The above data indicate that during the formation of Xigaze forearc basin, along with the strong early Cretaceous prearc extension, partial melting of the depleted mantle was induced, resulting in the formation of basic rocks different from typical island arc magmatic rocks. It is possible that the trench retreated during the northward subduction of the Neo-Tethys ocean and a strong mantle corner current was formed in front of the arc. At the same time, Xigaze forearc basin may be built on the early Jurassic crystalline rock series.
【作者單位】： 中國(guó)地質(zhì)科學(xué)院地質(zhì)研究所;中國(guó)地質(zhì)科學(xué)院礦產(chǎn)資源研究所;
【基金】：公益性行業(yè)科研專項(xiàng)(201511022) 國(guó)家重點(diǎn)研發(fā)計(jì)劃(2016YFC0600304) 國(guó)家自然科學(xué)基金項(xiàng)目(41425010)聯(lián)合資助
【分類號(hào)】：P534.53;P542

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 張傳恒,張世紅;弧前盆地研究進(jìn)展綜述[J];地質(zhì)科技情報(bào);1998年04期

2 W.Van der Werff ,蔡群昌;東巽他弧的龍自弧前盆地的新生代演化和地震地層[J];海洋地質(zhì)譯叢;1994年06期

3 郝杰,李日俊;日喀則殘留型弧前盆地的構(gòu)造與沉積演化[J];中國(guó)科學(xué)院研究生院學(xué)報(bào);1997年01期

4 閆全人,王宗起,A.D.Hanson,P.A.Druschke,王濤,閆臻;南秦嶺橫丹濁積巖系——晚古生代發(fā)育于揚(yáng)子板塊被動(dòng)陸緣上的弧前盆地充填物[J];地質(zhì)通報(bào);2002年Z2期

5 楊宗讓;川西松潘-甘孜弧前盆地的形成及演化[J];沉積與特提斯地質(zhì);2002年03期

6 郝杰,柴育成,李繼亮;雅魯藏布江蛇綠巖的形成與日喀則弧前盆地沉積演化[J];地質(zhì)科學(xué);1999年01期

7 賈建稱,溫長(zhǎng)順,王根厚,張振利,汪立軍;西藏仲巴縣窮果北部日喀則弧前盆地地層再認(rèn)識(shí)[J];西北地質(zhì);2005年02期

8 G.Einsele;S.Dürr;W.Frisch;劉光華;H.P.Luterbacher;L.Ratschbacher;W.Ricken;J.Wendt;A.Wetzel;劉寶s，

本文編號(hào)：2156136