本文關(guān)鍵詞：拉薩地體南北兩側(cè)碰撞后巖漿作用的巖漿起源和巖石成因　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 巖漿起源 巖石成因 碰撞后巖漿作用 拉薩地體 青藏高原

【摘要】：拉薩地體南北兩側(cè)的拉薩-羌塘弧-陸或弧-弧碰撞帶和印度-歐亞陸-陸碰撞帶均發(fā)育大量同碰撞到碰撞后巖漿巖,是研究碰撞后巖漿作用成因和機(jī)制、碰撞帶大陸地殼生長(zhǎng)的理想地區(qū)。已有研究主要集中在區(qū)域性年代學(xué)框架和構(gòu)造背景的探討,對(duì)這些巖漿活動(dòng)的巖漿源區(qū)和巖漿作用過程還缺乏精細(xì)的刻畫。本論文選取了這兩條碰撞帶典型的碰撞后巖漿活動(dòng)為對(duì)象,對(duì)其巖漿起源和巖石成因開展了詳細(xì)研究。在拉薩-羌塘碰撞帶發(fā)現(xiàn)區(qū)域性角度不整合面之上的約90 Ma富鎂火山巖,除1件樣品外,多數(shù)富鎂火山巖樣品均不具有埃達(dá)克巖的地球化學(xué)特征,它們具有負(fù)的?Nd(t)值(?3.2~?1.7)和低的初始(87Sr/86Sr)i值(0.7054~0.7065),顯示正的鋯石?Hf(t)值(+5.6~+8.7)和全巖?Hf(t)值(+3.8~+7.0),指示富鎂安山巖可能來自于拆沉鎂鐵質(zhì)下地殼(包括跨越中部和北部拉薩地塊的地殼底部)的部分熔融,該熔體隨后經(jīng)歷了熔體與軟流圈地幔橄欖巖的相互作用和淺部巖漿房高分異巖漿組分的改造,角閃石的分離結(jié)晶導(dǎo)致了安山巖向英安巖的成分轉(zhuǎn)變。結(jié)合野外地質(zhì)觀察、同期火山巖的年代學(xué)和地球化學(xué)數(shù)據(jù),指示卓嘎普富鎂火山巖和北部拉薩地體的同期巖漿作用,很可能是拉薩-羌塘碰撞之后增厚巖石圈拆沉作用的結(jié)果。在印度-歐亞碰撞帶岡底斯巖基首次發(fā)現(xiàn)同時(shí)侵位的約43 Ma中等程度分異和高分異的花崗巖,中等程度分異的花崗巖具有變化的分異指數(shù)(DI=84~93),低的重稀土元素(HREEs)和Y含量;高分異花崗巖樣品以高的Si O2含量(75~78 wt.%)和分異指數(shù)(DI=95~97)以及更加明顯的Ba、Sr、P和Ti元素的負(fù)異常為特征。這兩組樣品的鋯石?Hf(t)值和全巖Nd Hf Pb同位素組成相似,指示兩組來源于一個(gè)共同的以石榴子石作為殘留礦物相的源區(qū)。中等程度分異的樣品可能來自南部拉薩地體新生下地殼中的含石榴子石角閃巖(而不是榴輝巖)的部分熔融,并且混入了來自古老印度大陸和(或者)中部拉薩地體古老基底的富集組分,高分異花崗巖則是進(jìn)一步分離結(jié)晶(斜長(zhǎng)石、鉀長(zhǎng)石、黑云母、磷灰石、榍石等)的產(chǎn)物。結(jié)合區(qū)域研究,提出兩者很可能是印度-歐亞碰撞后新特提斯洋殼板片斷離的后續(xù)巖漿響應(yīng)。它們低的HREEs和Y含量以及高分異花崗巖的出現(xiàn)均指示了岡底斯地殼在約43 Ma已經(jīng)增厚了。通過對(duì)青藏高原大量已知不同成因類型花崗巖鋯石微量元素的分析,發(fā)現(xiàn)I型花崗巖以低的Pb豐度、高的(Nb/Pb)N比值為特征,明顯不同于S型花崗巖鋯石,而A型花崗巖類的這些參數(shù)的變化范圍介于I型和S型花崗巖類之間。這些差異對(duì)利用鋯石微量元素鑒別碰撞后花崗巖的成因類型提供了可能。
[Abstract]:The Lhasa-Qiangtang arc-land or arc-arc collision zone and the India-Eurasian continental collision zone on both sides of Lhasa-Qiangtang arc-arc collision zone on both sides of Lhasa terrane have developed a large number of post-collision magmatic rocks, which is the origin and mechanism of post-collision magmatism. An ideal area for continental crustal growth in collision zones. Previous studies have focused on the regional chronological framework and tectonic background. The magmatic source region and magmatism process of these magmatic activities are not well described. In this paper, the typical post-collision magmatic activity of these two collision zones is selected as the object. The magma origin and petrogenesis are studied in detail. In the Lhasa-Qiangtang collision zone, about 90 Ma mafic volcanic rocks, except one sample, were found on the regional unconformable surface. Most mafic volcanic samples do not have the geochemical characteristics of the adakite, and they are negative? Ndt) value? 3.2? 1. 7) and a low initial value of 87 Sr / 86 Sr ~ (2 +) = 0. 7054 ~ 0. 7065, indicating positive zircon? Value (5.6 ~ 8.7) and whole rock? The HfT values (3.8 ~ 7.0) indicate that the mafic-rich andesite may have originated from partial melting of the lower crust (including the bottom of the crust across the central and northern Lhasa massif). The melt then experienced the interaction between the melt and the mantle peridotite in the asthenosphere and the transformation of the high content heterogeneous magma components in the shallow magma chamber. The separation and crystallization of amphibole resulted in the composition transformation from andesite to dolomite. Combined with field geological observations, the geochronology and geochemistry data of volcanic rocks in the same period were obtained. It indicates the contemporaneous magmatism of the Zhuogapu mafic volcanic rocks and the Lhasa terrane in the north. It is very likely that it is the result of thickening lithosphere delamination after the Lhasa-Qiangtang collision. In the India-Eurasian collision zone, the Gangdis rock base was the first to be emplaced at about 43 Ma with moderate differentiation and high differentiation. The moderately differentiated granites have a variable differentiation index (DI _ (84) ~ (93)), low heavy REE _ (es) and Y contents; The samples of high grade isomorphic granites are characterized by high Sio _ 2 content (75 ~ 78wt.) and differentiation index (~ (95 ~ (97))), as well as more obvious Ba~ (+) Sr. The negative anomalies of P and Ti elements are characterized by zircon from these two groups of samples. The values of HF ~ (t) are similar to the isotopic compositions of ND ~ (+) HF ~ (+) Pb in the whole rock. The results indicate that the two groups are derived from a common source with pomegranate as the residual mineral facies. The moderately differentiated samples may come from the eclogite amphibolite (rather than eclogite) from the Cenozoic lower crust of the Lhasa terrane in southern Lhasa. Partial melting. And mixed with the enrichment components from the ancient basement of the ancient Indian continent and / or central Lhasa terrane, the high-grade isomorphic granite is further separated and crystallized (plagioclase, potassium feldspar, biotite, apatite). The product of sphene, etc. It is suggested that both of them may be the subsequent magmatic response to the partial separation of the NeoTethys oceanic crust after the India-Eurasian collision. Their low HREEs and Y contents and the presence of high-grade isomorphic granites all indicate that the Gangdis crust is located in about 4. 4% of the earth's crust. 3. Ma has been thickened. Based on the analysis of zircon trace elements of a large number of known granites of different genetic types in the Qinghai-Xizang Plateau. It is found that the I-type granite is characterized by low Pb abundance and high NB / PbN ratio, which is obviously different from the zircon of S-type granite. The variation range of these parameters of A-type granitoids is between I-type and S-type granitoids. These differences make it possible to identify the genetic types of post-collision granites by zircon trace elements.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：P588.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 劉函;王保弟;陳莉;李小波;王立全;;拉薩地塊西北日土花崗巖基鋯石U-Pb年代學(xué)、地球化學(xué)及構(gòu)造意義[J];大地構(gòu)造與成礦學(xué);2015年06期

2 孟元庫(kù);許志琴;陳希節(jié);馬緒宣;賀振宇;張雪松;;藏南岡底斯中段謝通門始新世復(fù)式巖體鋯石U-Pb年代學(xué)、Hf同位素特征及其地質(zhì)意義[J];大地構(gòu)造與成礦學(xué);2015年05期

3 雷鳴;陳建林;許繼峰;曾云川;;拉薩地體中北部尕爾窮晚白堊世早期高鎂閃長(zhǎng)玢巖地球化學(xué)特征指示:加厚下地殼的拆沉?[J];地質(zhì)通報(bào);2015年Z1期

4 張向飛;李佑國(guó);曹曉民;曲曉明;辛洪波;王健;杜德道;;班公湖—怒江縫合帶西段酸性侵入巖LA-ICP-MS鋯石U-Pb年齡與地球化學(xué)特征[J];地質(zhì)通報(bào);2014年07期

5 黃瀚霄;李光明;陳華安;石洪召;劉波;祝向平;曾慶高;李志;;西藏色布塔銅鉬礦床中輝鉬礦Re-Os定年及其成礦意義[J];地質(zhì)學(xué)報(bào);2013年02期

6 姚曉峰;唐菊興;李志軍;鄧世林;丁帥;胡正華;張志;;班公湖—怒江帶西段尕爾窮矽卡巖型銅金礦含礦母巖成巖時(shí)代的重新厘定及其地質(zhì)意義[J];地質(zhì)論評(píng);2013年01期

7 王保弟;許繼峰;劉保民;陳建林;王立全;郭琳;王冬兵;張萬平;;拉薩地塊北部～90Ma斑巖型礦床年代學(xué)及成礦地質(zhì)背景[J];地質(zhì)學(xué)報(bào);2013年01期

8 叢源;肖克炎;翟慶國(guó);董慶吉;;西藏南木林普洛崗巖體鋯石定年和Hf同位素特征及其地質(zhì)意義[J];吉林大學(xué)學(xué)報(bào)(地球科學(xué)版);2012年06期

9 胡正華;丁楓;唐菊興;李志軍;姚曉峰;鄧世林;張志;王藝云;王紅星;宋俊龍;陳偉;;西藏革吉縣尕爾窮銅金礦床地質(zhì)特征及其成因意義[J];地球?qū)W報(bào);2012年04期

10 朱弟成;趙志丹;牛耀齡;王青;Yildirim DILEK;董國(guó)臣;莫宣學(xué);;拉薩地體的起源和古生代構(gòu)造演化[J];高校地質(zhì)學(xué)報(bào);2012年01期

相關(guān)博士學(xué)位論文 前2條

1 王建剛;西藏日喀則地區(qū)喜馬拉雅造山帶沉積記錄與盆地演化[D];南京大學(xué);2011年

2 徐旺春;西藏岡底斯花崗巖類鋯石U-Pb年齡和Hf同位素組成的空間變化及其地質(zhì)意義[D];中國(guó)地質(zhì)大學(xué);2010年

相關(guān)碩士學(xué)位論文 前3條

1 賈黎黎;藏南始新世早期基性巖的地球化學(xué)特征區(qū)域性變化及其構(gòu)造意義[D];中國(guó)地質(zhì)大學(xué)（北京）;2014年

2 董昕;西藏岡底斯帶西南部中新生代花崗巖年代學(xué)與地球化學(xué)[D];中國(guó)地質(zhì)大學(xué)（北京）;2008年

3 李志國(guó);西藏措麥林子宗群年波組火山巖地球化學(xué)及其意義[D];中國(guó)地質(zhì)大學(xué)（北京）;2007年

，

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