本文選題：揚(yáng)子地臺(tái)　切入點(diǎn)：超基性巖　出處：《地質(zhì)通報(bào)》2017年Z1期

【摘要】：白層超基性巖產(chǎn)出于揚(yáng)子地臺(tái)西南緣,該區(qū)域存在多期次的巖漿活動(dòng),出露多處超基性巖體。對(duì)白層11件超基性巖樣品進(jìn)行了主量和微量元素(包括稀土元素)及鉑族元素分析,結(jié)果表明,白層超基性巖主量元素變化范圍不大,具低鈉富鉀鈣堿性巖石的地球化學(xué)特征;該超基性巖富集Ba、Sr、Rb等大離子親石元素及Nb等高場(chǎng)強(qiáng)元素;稀土元素總量高,球粒隕石標(biāo)準(zhǔn)化曲線呈強(qiáng)烈的右傾趨勢(shì),輕、重稀土元素分餾明顯,Eu、Ce異常不明顯;鉑族元素總含量低,且分異不明顯。該超基性巖的地球化學(xué)特征顯示,其形成于燕山晚期右江盆地大規(guī)模巖石圈伸展減薄的構(gòu)造背景下;巖漿來(lái)源于低程度部分熔融的超鎂鐵質(zhì)地幔,石榴子石及硫化物在熔融過(guò)程中殘留于源區(qū)。巖漿在上升過(guò)程中未發(fā)生明顯的地殼物質(zhì)混染。巖漿結(jié)晶分異程度不高,發(fā)生了橄欖石與單斜輝石的結(jié)晶分異但未發(fā)生斜長(zhǎng)石的分離。
[Abstract]:The ultrabasic rocks occurred in the southwestern margin of the Yangtze platform, and there were many magmatic activities in this area. The principal and trace elements (including rare earth elements) and platinum group elements of 11 ultrabasic rock samples in the white layer are analyzed. The results show that the main elements of the ultrabasic rocks in the white bed have little change. The ultrabasic rocks are rich in large ion lithophile elements, such as Ba-Sr-Rb and NB, and have high rare earth elements, and the standardized curve of chondrites shows a strong right-dip trend, which is light, and it is characterized by the geochemical characteristics of low-sodium and K-rich calc-alkaline rocks, the ultrabasic rocks are enriched in large ion lithophile elements, such as Ba-Sr-Rb and NB and so on. The fractionation of heavy rare earth elements is not obvious, the total content of platinum group elements is low, and the differentiation is not obvious. The geochemical characteristics of the ultrabasic rock show that it was formed in the tectonic setting of large-scale lithospheric extension and thinning in the late Yanshanian basin. The magma originated from the low-degree partial melting ultramafic mantle, and the pomegranate and sulfides remained in the source region during the melting process. There was no obvious crustal material mixing during the magma rising, and the degree of crystallization differentiation of the magma was not high. The crystal differentiation of olivine and clinopyroxene occurs but no separation of plagioclase occurs.
【作者單位】： 中國(guó)地質(zhì)大學(xué)地球科學(xué)與資源學(xué)院;中國(guó)地質(zhì)調(diào)查局成都地質(zhì)調(diào)查中心;
【基金】：中國(guó)地質(zhì)調(diào)查局項(xiàng)目《貴州貞豐金-鈾多金屬成礦區(qū)控礦因素與找礦方法研究》(編號(hào):12120113094400)
【分類號(hào)】：P588.125;P588.115

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