新疆西准洪古勒楞蛇绿岩地球化学特征及构造环境
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摘要
对西准噶尔洪古勒楞蛇绿混杂岩带进行了较系统的岩石学、地球化学和年代学方面的研究,认为其主体由超镁铁质杂岩、堆晶岩类、镁铁质岩墙、基性熔岩和深海沉积组成。岩石地球化学数据表明其具轻稀土富集、重稀土相对亏损的右倾分布模式特征,富集Ta,Yb等元素,相对富集Ba,U,Sr等元素,亏损Nb,Hf,Ti等元素,Nb具负异常,一定程度上反映其为地幔源区含岛弧火山岩组分,岩石化学数据显示该蛇绿岩形成构造环境为弧后盆地。堆晶辉长岩的LA-ICP-MS锆石U-Pb年龄为(497.2±4.2)Ma(MSWD=1.4,n=10),证实该蛇绿岩形成于晚寒武世。
Study on the petrological,geochemical characteristics and Geochronology of hongguleleng ophiolite located in the Western Junggar.The ophiolite composed predominantly of the ultramafic-mafic cumulates,mafic dyke,basic lava,and deep-sea sediments as well.Geochemical data analysis shows that the LREE enrichment and the HREE deficiency,general right deviation REE distribution pattern.It is relatively enriched in Ba、U、Sr, especially in Ta magma containe、Yb,but poor in Nb Nb anomaly.That reflects mantled constituents of isla、HfTi.It showed a negativend a、rc volcanic rocks.The geochemical characters shows that the ophiolite were occurred in back-arc basin environment.Zircon LA-ICP-MS U-Pb dating for the granite yielded an age of(497.2 4.2) Ma(MSWD=1.4,n=10), indicating the formation of the hongguleleng ophiolite is in Late Cambrian.
Study on the petrological,geochemical characteristics and Geochronology of hongguleleng ophiolite located in the Western Junggar.The ophiolite composed predominantly of the ultramafic-mafic cumulates,mafic dyke,basic lava,and deep-sea sediments as well.Geochemical data analysis shows that the LREE enrichment and the HREE deficiency,general right deviation REE distribution pattern.It is relatively enriched in Ba、U、Sr, especially in Ta magma containe、Yb,but poor in Nb Nb anomaly.That reflects mantled constituents of isla、HfTi.It showed a negativend a、rc volcanic rocks.The geochemical characters shows that the ophiolite were occurred in back-arc basin environment.Zircon LA-ICP-MS U-Pb dating for the granite yielded an age of(497.2 4.2) Ma(MSWD=1.4,n=10), indicating the formation of the hongguleleng ophiolite is in Late Cambrian.
引文
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?新疆维吾尔自治区地质调查院.1∶25万塔城幅区域地质调查报告,2012
[2]董连慧,朱志新,屈迅,等.新疆蛇绿岩带的分布、特征及研究新进展[J].岩石学报,2010,26(10):2894-2904.
[3]黄汲清,任纪舜,姜春发,等.中国大地构造及其演化[M].北京:科学出版社,2010.
[4]新辐维吾尔自治区域地层表编写组(CGRST).西北地区区域地层表新疆维维吾尔自治区分册[M].北京:地质出版社,I981,1-496.
[5]何周琦,李茂松,刘德权,等.中国新疆古生代地壳演化与成矿[M].乌鲁木齐:新疆人民出版社,1994,l-477.
[6]张旗.云南双沟蛇绿岩的特征和成因[J].岩石学报,1995,11(增刊):190-202.
[7]Pearce J A,Cann J R.Tectionic setting of basic volcanic rocks determined using trace element analyses[J].Earth and Pllanetary Science Letters,1973,19;290-300.
[8]Sun SS,Mc Donough WF.Chemical and isotopic systematic of oceanic basalts:implication for mantle composition and processes[J].Geoligical Society of London,1989,42:313-345.
[9]Elliott T,Plank T,Zindler A,White W and Bourdon B.Elementstransport from slab to volcanic front the Mariana arc[J].Journal of Geophysical Research,1997,102:14991-15019.
[10]Wilson M.Igneous Petrogenesis[M].London:Unwin Hyman,1989,1-466.
[11]Colenmn R.Continental growth of Norihwesl China.Fectoni,S,1989,8:621-635.
[12]张旗,周国庆.中国蛇绿岩[M].北京:科学出版社,2001,1-15.
[13]王保弟,许继峰,曾庆高,等.西藏改则地区拉果错蛇绿岩地球化学特征及成因,岩石学报,2007,23(6).
?新疆维吾尔自治区地质调查院.1∶25万塔城幅区域地质调查报告,2012