新疆地质
新疆地質
신강지질
Xinjiang Geology
2015年
3期
318-322
,共5页
西准噶尔%科克萨依蛇绿岩%岩石地球化学%洋岛玄武岩
西準噶爾%科剋薩依蛇綠巖%巖石地毬化學%洋島玄武巖
서준갈이%과극살의사록암%암석지구화학%양도현무암
Western Jungger%Kekesayi Ophiolite%Geochemistry%Oceanic island basalt
新疆西准噶尔地区的科克萨依蛇绿岩带，为一套由蛇纹岩、枕状玄武岩及安山玄武质凝灰熔岩、辉长岩（辉绿岩墙）、硅质岩构成的混杂岩带。选择组合中的枕状玄武岩进行地球化学研究，结果表明，玄武岩以低镁（Mg#=0.27~0.33）、高钛（1.31%~2.43%）为特征；稀土分布有 LREE 富集（La/Yb）N=9.22~13.01，无明显 Eu 异常（δEu=0.95~1.15）；Rb，Sr略显负异常，高场强元素（Nb，Ta，Zr，Hf，Ti，P）相对OIB型玄武岩无明显异常。稀土元素及微量元素分布模式与洋岛玄武岩基本一致，具典型洋岛（海山）型玄武岩特征。综合研究认为，科克萨依玄武岩形成于大洋板内洋岛（海山）环境。
新疆西準噶爾地區的科剋薩依蛇綠巖帶，為一套由蛇紋巖、枕狀玄武巖及安山玄武質凝灰鎔巖、輝長巖（輝綠巖牆）、硅質巖構成的混雜巖帶。選擇組閤中的枕狀玄武巖進行地毬化學研究，結果錶明，玄武巖以低鎂（Mg#=0.27~0.33）、高鈦（1.31%~2.43%）為特徵；稀土分佈有 LREE 富集（La/Yb）N=9.22~13.01，無明顯 Eu 異常（δEu=0.95~1.15）；Rb，Sr略顯負異常，高場彊元素（Nb，Ta，Zr，Hf，Ti，P）相對OIB型玄武巖無明顯異常。稀土元素及微量元素分佈模式與洋島玄武巖基本一緻，具典型洋島（海山）型玄武巖特徵。綜閤研究認為，科剋薩依玄武巖形成于大洋闆內洋島（海山）環境。
신강서준갈이지구적과극살의사록암대，위일투유사문암、침상현무암급안산현무질응회용암、휘장암（휘록암장）、규질암구성적혼잡암대。선택조합중적침상현무암진행지구화학연구，결과표명，현무암이저미（Mg#=0.27~0.33）、고태（1.31%~2.43%）위특정；희토분포유 LREE 부집（La/Yb）N=9.22~13.01，무명현 Eu 이상（δEu=0.95~1.15）；Rb，Sr략현부이상，고장강원소（Nb，Ta，Zr，Hf，Ti，P）상대OIB형현무암무명현이상。희토원소급미량원소분포모식여양도현무암기본일치，구전형양도（해산）형현무암특정。종합연구인위，과극살의현무암형성우대양판내양도（해산）배경。
The Ophiolite of Kekesayi district in western Jungger of XinJiang,is a melange belt formed of serpentinite, pillow basalt,andesite-basaltic tuff lava,gabbro(diabase dyke) and siliceous rock.We have done a detailed geochemical study on the pillow basalt from the association. It turned out that the basalt is characterised by the low magnesium(Mg#=0.27~0.33)and high titanium(1.31%~2.43%);the REE pattern shows the enrichment of LREE(La/Yb)N=9.22~13.01 and unobvious Eu anomaly(δEu=0.95~1.15);Rb and Sr show a little negative anomaly.Comparing to the oceanic island basalt,the high field-strength elements(Nb,Ta,Zr,Hf,Ti,P) show unobvious anomaly.The trace elements and REE distribu-tion patterns are similar to those of the oceanic island basalt(OIB),which indicates they have the characteristics of the typical oceanic island basalt.The comprehensive study suggests that the basalt in the Kekesayi is formed in the oceanic island(seamount) environment within the oceanic plate.This provides a new basis for the hot point activity in oceanic plate of western junggar kekesayi region.
