Age and geochemical studies on gabbro at Kayakedengtage, East Kunlun, Qinghai Province show that the gabbro was emplaced during Early Devonian belonging Ca-alklic series with evolution trend to Mg enrichment. The Σ REE are in range 28. 9 X 10-6 to 154 X 10-6 with the obvious enrichment of LREE[(La/Yh)=4. 1-5. 1(>1)( LREE/HREE 3. 52-5. 60), Sm/Nd of rocks 0. 23-0. 25, showing derivation of the gabbro from the depleted mantle. However, δ(Ce)= 0. 87-1. 0, the negative Ce anomaly indicates derivation of the gabbro from contact zone of mantle and crust or the enriched mantle. Combined with the basalt tectonic discrimination diagrams, the gabbro may be the product of the post Caledonian Qi-mantage orogen extensional environment.%文章通过对东昆仑喀雅克登塔格地区的辉长岩时代及地球化学研究发现,该辉长岩侵位于早泥盆世,属钙碱性系列,有向富镁方向演化的特点,岩石稀土总量为28.9×10-6～154×10-6,(La/Yb)N=4.1～5.1(＞1),显示岩石轻稀土富集的特点(LREE/HREE=3.52～5.60),岩石的Sm/Nd=0.23～0.25,指示来源区可能与亏损地幔有关.δ(Ce)=0.87～1.00,为铈的负异常,辉长岩来源于壳幔接合部位或富集型地幔源区.结合玄武岩构造环境判别图解可知,本区辉长岩应为祁漫塔格加里东造山带造山后伸展环境下的产物.
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