西天山琼阿乌孜超基性岩体的稀土元素和Sr、Nd同位素研究  

REE and Sr-Nd Isotopic Study of Qiongawuzi Ultramafic Intrusion, West Tianshan

作　　者：倪守斌[1] 满发胜[1] 陈江峰[1] 

机构地区：[1]中国科学技术大学地球空间科学系

出　　处：《岩石学报》1995年第1期65-70,共6页Acta Petrologica Sinica

基　　金：国家"七五"攻关项目

摘　　要：对西天山琼阿乌孜超基性岩体和围岩片麻岩作了Ｓｍ、Ｎｄ、Ｒｂ、Ｓｒ同位素和稀土元素的研究，获得岩体的形成年龄为３１４±１９Ｍａ，∑ＲＥＥ约为４．０～７．６μｇ／ｇ。其主体岩石是由来源于未亏损地幔较高程度熔融而产生的岩浆在结晶分异作用中形成。其岩体的边缘［εＮｄ＝－５，（８７Ｓｒ／８６Ｓｒ）＝０．７０５５，∑ＲＥＥ＝１１１．５６μｇ／ｇ］同化了围岩［εＮｄ＝－１６．７，（８７Ｓｒ／８６Ｓｒ）ｉ＝０．７５３７，∑ＲＥＥ＝１９６μｇ／ｇ］，并同时发生结晶作用，经历了ＡＦＣ过程，形成了特有的琼阿鸟孜超基性岩侵入体。REE Concentrations and Sr and Nd isotope compositions are analysed for samples from Qiongawuzi ultramafic intrusion and its country rock, west Tianshan Mountains of Xinjiang. ∑REE contents of ultramafic rocks, gabbro in marginal factes and country rock are about 4～7. 6μ/g, 112μ/g and 196μg/g,respectively. εNd and (87r/86Sr)i of gabbro and country rock samples are-5. 0, -16. 7 and 0. 7055, 0. 7537.Sm-Nd mineral isochron gives an age of 314±19 Ma. REE patterns suggest that ultramafic rocks are very likely cumulates of gabbroic magma formed by large percent of partial melting of the mantle. This marginal gabbro is formed by AFC (assimilation coupled with fractional crystallization) process. This indicates that the intrusion is not a part of ophiolite suit but a product of magmatism.

关 键 词：超基性岩 锶同位素 钕同位素 稀土族 

分 类 号：P588.125[天文地球—岩石学]